[Ka-eL]

Hi Group!!, Novice in wiring here.. I have a Guitar Cabinet Hartke
(4x10) GH410a that has four 16 Ohms speaker, w/ 4 or 16 Ohm mono and 8
Ohm stereo switch on the input Jack.. I would like to upgrade the
speakers to four 8 Ohm.. No knowledge in impedance on speakers, but
I've heard that I need to revise my wiring? and find out what is the
total Ohm of the cabinet? w/ the switch from Mono 4-16 Ohm and Stereo 8
Ohm.. what will be my cabinet Ohm? do I need to replace the speaker
Jack inputs for 8 Ohm? I appreciate any Help!!

[[email protected]]

Ka-eL wrote:
Hi Group!!, Novice in wiring here.. I have a Guitar Cabinet Hartke
(4x10) GH410a that has four 16 Ohms speaker, w/ 4 or 16 Ohm mono and 8
Ohm stereo switch on the input Jack.. I would like to upgrade the
speakers to four 8 Ohm.. No knowledge in impedance on speakers, but
I've heard that I need to revise my wiring? and find out what is the
total Ohm of the cabinet? w/ the switch from Mono 4-16 Ohm and Stereo 8
Ohm.. what will be my cabinet Ohm? do I need to replace the speaker
Jack inputs for 8 Ohm? I appreciate any Help!!

Your cabinet probably has four 4 Ohm speakers in it now. Speaker wiring
works like this:
If you have two speakers in series, the Ohms add. If you wire them in
parallel and all speakers have the same Ohms, the total Ohms is divided
by the number of speakers.

So If you have four, 4 ohm speakers and wire them all in series 4+4+4+4
= 16 Ohms.
If you wire two in series and the other two in series you have two sets
each of 8 Ohms. (stereo)
If you wire those two 8 Ohm stereo sets of two in parallel you get half
the value or 4 Ohms.

If you "upgrade" the cabinet to four 8 Ohm speakers you could wire all
in parallel to get 8/4 or 2 Ohms. This will only work if your amp can
handle a 2 Ohm load. Most can't. Or you could wire two in series giving
a stereo pair of 16 Ohms each. IF you wire those in parallel you'd get
half the value or 8 Ohms total. So the catch is that you probably need
4 Ohms (unless it's a tube amp) to get max power out. And with your new
speakers you can't wire them to get 4 Ohms! So you are going to lose
output power with the new speakers! Best would be to find new 4 Ohm
speakers or alternatively find another cabinet and wire those two cabs
in parallel so that 8 and 8 in parallel gives you the final 4 Ohms you
need.

[Gareth Magennis]

"Ka-eL" wrote in message
ups.com...
Hi Group!!, Novice in wiring here.. I have a Guitar Cabinet Hartke
(4x10) GH410a that has four 16 Ohms speaker, w/ 4 or 16 Ohm mono and 8
Ohm stereo switch on the input Jack.. I would like to upgrade the
speakers to four 8 Ohm.. No knowledge in impedance on speakers, but
I've heard that I need to revise my wiring? and find out what is the
total Ohm of the cabinet? w/ the switch from Mono 4-16 Ohm and Stereo 8
Ohm.. what will be my cabinet Ohm? do I need to replace the speaker
Jack inputs for 8 Ohm? I appreciate any Help!!



The only thing you can do with 4 x 8 ohm speakers is have a cabinet of 8
ohms mono or 2 x 4 ohms or 2 x 16 ohmns stereo. Is this what you want?



Gareth.

[Oci-One Kanubi]

Why do you think going from 16 ohms to 8 ohms represents an upgrade?

Or do you mean: "I am upgrading to a better quality speaker, but the
old ones are 16 ohm and the new ones are 8 ohm"?

If it is the first case, if you think reducing the impedance on the
speakers represents an upgrade: it doesn't. Don't do it unless the
whole point of the exercise is to change the impedance values of the
cabinet to match the optimum requirements of the amp head.

If it is the second case, and you need to end up with the same overall
cabinet values you have now, then you need to find better-quality 16
ohm speakers or better-quality 4 ohm speakers; either set can be wired
to yield mono 4/16 or stereo 8, but as another respondent told you, 8s
cannot be wired to yield the same final values.

Screwing this up can wreck yer amp head if you wind up with
insufficient impedance, or reduce yer output power if you wind up with
too much. So, first shop around and find either 4s or 16s of the
quality you are after, then get back to us for the wiring diagram.

-Richard, His Kanubic Travesty
--
================================================== ====================
Richard Hopley Winston-Salem, NC, USA
.. rhopley[at]earthlink[dot]net
.. Nothing really matters except Boats, Sex, and Rock'n'Roll
.. rhopley[at]wfubmc[dot]edu
.. OK, OK; computer programming for scientific research also matters
================================================== ====================


Ka-eL wrote:
Hi Group!!, Novice in wiring here.. I have a Guitar Cabinet Hartke
(4x10) GH410a that has four 16 Ohms speaker, w/ 4 or 16 Ohm mono and 8
Ohm stereo switch on the input Jack.. I would like to upgrade the
speakers to four 8 Ohm.. No knowledge in impedance on speakers, but
I've heard that I need to revise my wiring? and find out what is the
total Ohm of the cabinet? w/ the switch from Mono 4-16 Ohm and Stereo 8
Ohm.. what will be my cabinet Ohm? do I need to replace the speaker
Jack inputs for 8 Ohm? I appreciate any Help!!

[Lord Vader]

Thanks for the reply. Not quite follow your instruction(?) The cabinet
currently has four 16 Ohms speakers.. Like to upgrade w/ a better
speakers but there four 8 Ohms.. now, the wiring has to be change,
right? here's how there wired right now w/ the four 16 Ohms stock
speakers.. 2 speakers are wired half-tap (+) (-) w/ the other 2
speakers (+) (-)..and top 2 speakers are wired directly to the switch
input. I Like to leave the 4 or 16 Ohm mono and 8 Stereo Ohm
(multi-Ohm?) switch operation,if possible.. If I were to change the
four 16 Ohms w/ four 8 ohms which wiring sequence? Thanks for the
Help!!!

wrote:

Your cabinet probably has four 4 Ohm speakers in it now. Speaker wiring
works like this:
If you have two speakers in series, the Ohms add. If you wire them in
parallel and all speakers have the same Ohms, the total Ohms is divided
by the number of speakers.

So If you have four, 4 ohm speakers and wire them all in series 4+4+4+4
= 16 Ohms.
If you wire two in series and the other two in series you have two sets
each of 8 Ohms. (stereo)
If you wire those two 8 Ohm stereo sets of two in parallel you get half
the value or 4 Ohms.

If you "upgrade" the cabinet to four 8 Ohm speakers you could wire all
in parallel to get 8/4 or 2 Ohms. This will only work if your amp can
handle a 2 Ohm load. Most can't. Or you could wire two in series giving
a stereo pair of 16 Ohms each. IF you wire those in parallel you'd get
half the value or 8 Ohms total. So the catch is that you probably need
4 Ohms (unless it's a tube amp) to get max power out. And with your new
speakers you can't wire them to get 4 Ohms! So you are going to lose
output power with the new speakers! Best would be to find new 4 Ohm
speakers or alternatively find another cabinet and wire those two cabs
in parallel so that 8 and 8 in parallel gives you the final 4 Ohms you
need.

[Lord Vader]

Thanks for the Reply.. What I tryin' to do is upgrade the stock (four
16 Ohms) 10 "speakers w/ better speakers w/ lots of low end. I haven't
seen any 16 Ohms replacement most or all of them are 8 Ohms.. You said
I have to get 16 or 4 Ohms enable to use the 4/16 Mono and 8 Stero Ohm
switch? If I go with four 8 Ohms, then I need to replace the input
switch thats just 8 Ohms? Thanks for the Help!!

Oci-One Kanubi wrote:
Why do you think going from 16 ohms to 8 ohms represents an upgrade?

Or do you mean: "I am upgrading to a better quality speaker, but the
old ones are 16 ohm and the new ones are 8 ohm"?

If it is the first case, if you think reducing the impedance on the
speakers represents an upgrade: it doesn't. Don't do it unless the
whole point of the exercise is to change the impedance values of the
cabinet to match the optimum requirements of the amp head.

If it is the second case, and you need to end up with the same overall
cabinet values you have now, then you need to find better-quality 16
ohm speakers or better-quality 4 ohm speakers; either set can be wired
to yield mono 4/16 or stereo 8, but as another respondent told you, 8s
cannot be wired to yield the same final values.

Screwing this up can wreck yer amp head if you wind up with
insufficient impedance, or reduce yer output power if you wind up with
too much. So, first shop around and find either 4s or 16s of the
quality you are after, then get back to us for the wiring diagram.

-Richard, His Kanubic Travesty
--
================================================== ====================
Richard Hopley Winston-Salem, NC, USA
. rhopley[at]earthlink[dot]net
. Nothing really matters except Boats, Sex, and Rock'n'Roll
. rhopley[at]wfubmc[dot]edu
. OK, OK; computer programming for scientific research also matters
================================================== ====================

[Don Pearce]

On 7 Nov 2006 18:58:05 -0800, "Lord Vader"
wrote:

Thanks for the reply. Not quite follow your instruction(?) The cabinet
currently has four 16 Ohms speakers.. Like to upgrade w/ a better
speakers but there four 8 Ohms.. now, the wiring has to be change,
right? here's how there wired right now w/ the four 16 Ohms stock
speakers.. 2 speakers are wired half-tap (+) (-) w/ the other 2
speakers (+) (-)..and top 2 speakers are wired directly to the switch
input. I Like to leave the 4 or 16 Ohm mono and 8 Stereo Ohm
(multi-Ohm?) switch operation,if possible.. If I were to change the
four 16 Ohms w/ four 8 ohms which wiring sequence? Thanks for the
Help!!!

First question. What does w/ mean?

Next question. What does half-tap (+) (-) mean?

Now for facts. You cannot replace four 16 ohm speakers with four 8 ohm
speakers and replicate the overall impedances you had before - it
simply won't happen, however you wire them. You need to find yourself
16 ohm replacements from somewhere.

d

--
Pearce Consulting
http://www.pearce.uk.com

[Lord Vader]

Don Pearce wrote:

First question. What does w/ mean?

"W/" is short for "With" .. Like "btw" which is "By the way"


Next question. What does half-tap (+) (-) mean?

Wires connecting the 2 speakers. hafltap the red (+) and black (-)
wires to the other pair speakers.. like parallel series?


Now for facts. You cannot replace four 16 ohm speakers with four 8 ohm
speakers and replicate the overall impedances you had before - it
simply won't happen, however you wire them. You need to find yourself
16 ohm replacements from somewhere.

That's my dilemna. most 10" speakers are 8 Ohm..



--
Pearce Consulting
http://www.pearce.uk.com

[Don Pearce]

On 7 Nov 2006 21:29:21 -0800, "Lord Vader"
wrote:



Don Pearce wrote:

First question. What does w/ mean?

"W/" is short for "With" .. Like "btw" which is "By the way"


Next question. What does half-tap (+) (-) mean?

Wires connecting the 2 speakers. hafltap the red (+) and black (-)
wires to the other pair speakers.. like parallel series?


Look, you can't explain the word halftap by using the word halftap.
Please try again using standard terminology.


Now for facts. You cannot replace four 16 ohm speakers with four 8 ohm
speakers and replicate the overall impedances you had before - it
simply won't happen, however you wire them. You need to find yourself
16 ohm replacements from somewhere.

That's my dilemna. most 10" speakers are 8 Ohm..

Then you are stuck.

d

--
Pearce Consulting
http://www.pearce.uk.com

[Ka-eL]

Don Pearce wrote:
On 7 Nov 2006 21:29:21 -0800, "Lord Vader"
wrote:



Don Pearce wrote:

First question. What does w/ mean?

"W/" is short for "With" .. Like "btw" which is "By the way"


Next question. What does half-tap (+) (-) mean?

Wires connecting the 2 speakers. hafltap the red (+) and black (-)
wires to the other pair speakers.. like parallel series?


Look, you can't explain the word halftap by using the word halftap.
Please try again using standard terminology.

Sorry dude, Like I said I'm a Novice..

Now for facts. You cannot replace four 16 ohm speakers with four 8 ohm
speakers and replicate the overall impedances you had before - it
simply won't happen, however you wire them. You need to find yourself
16 ohm replacements from somewhere.

That's my dilemna. most 10" speakers are 8 Ohm..

Then you are stuck.
Great!!!

Are you familiar w/ Stereo monitoring? if you check the wiring diagram
here
http://professional.celestion.com/gu...ibel/index.asp

Mine is the same on the 4x12 Stereo monitoring wiring.. but w/ 10" and
16 Ohm..
Website did not indicate the Ohm of the speakers, does that mean any it
can work
at any Ohm as long there all the same Impedance?.. Appreciate your time
and Help..


d

--
Pearce Consulting
http://www.pearce.uk.com

[Anahata]

Ka-el wrote:
[snip]

The bottom line is: however you wire them, you cannot use 4 x 8 ohm
speakers and make the combination look like 16 ohms.

If you put them all in parallel, that's 2 ohms.
If you put them all in series, it's 32 ohms.
If you put them in any series-parallel combination that distributes the
power equally between the speakers, it's 8 ohms.

With only two speakers, it's all different.
2 x 8 omhs in parallel = 4 ohms
2 x 8 ohms in series = 16 ohms

You can do the stero monitoring thing with:
Left = 2 x 8 ohms in series = 16 ohms
Right = the other 2 8 ohms in series = 16 ohms

(I'm not sure exactly what your want...)

Any combination that comes to a larger impedance than you had before is
safe to use with your amplifier, but your maximum power won't be so
high. That doesn't matter unless you were already maxing it out and it
was barely loud enough.

Maybe some part of the above will be some use to you.

Anahata

[Kloka-mo']

There ARE 16 Ohm replacement speakers:
http://tinyurl.com/y97fc4
http://tinyurl.com/y8th9g

You probably won't find them rated very high, because they are used for more
vintage sounding gear, or boxes of 4 -10 speakers, where the number of
speakers make up for their individual rating.

If it's for guitar, this should be PLENTY. For bass... it all depends.
What amp is going to be driving it, and what enclosure are these going to be
mounted in?

--
-rob Bartlett, TN
O
/(\)
^^
"Lord Vader" wrote in message
oups.com...
Thanks for the Reply.. What I tryin' to do is upgrade the stock (four
16 Ohms) 10 "speakers w/ better speakers w/ lots of low end. I haven't
seen any 16 Ohms replacement most or all of them are 8 Ohms.. You said
I have to get 16 or 4 Ohms enable to use the 4/16 Mono and 8 Stero Ohm
switch? If I go with four 8 Ohms, then I need to replace the input
switch thats just 8 Ohms? Thanks for the Help!!

[Mike Rivers]

Ka-eL wrote:
Hi Group!!, Novice in wiring here.. I have a Guitar Cabinet Hartke
(4x10) GH410a that has four 16 Ohms speaker, w/ 4 or 16 Ohm mono and 8
Ohm stereo switch on the input Jack.. I would like to upgrade the
speakers to four 8 Ohm.

These people will bicker forever over words and not really answer your
question. But the problem is that we don't really know what your
question is. Several people have explained how impedances combine in
series and parallel, but you won't really get any more assistance than
that until you let us know WHY you want to "upgrade" to 8 ohm speakers.
Do you just haver some 8 ohm speakers that you think sound better than
the originals?

What amplifier are you using it with? Is it a Hartke amplifier, or just
a Hartke speaker cabinet? What is the power rating and impedance of the
amplifier? If you're trying to make it louder, you may not be able to
do so. One amplifier may have its peak power at 4 ohms, while another
may have its peak power at 2 ohms, or 8 ohms, but all be called "100
watts."

Also, that stereo/mono wiring with a switch sounds pretty complicated.
Do you need to retain that capability?

[Oci-One Kanubi]

Lord Vader wrote:
Don Pearce wrote:

First question. What does w/ mean?

"W/" is short for "With" .. Like "btw" which is "By the way"


Next question. What does half-tap (+) (-) mean?

Wires connecting the 2 speakers. hafltap the red (+) and black (-)
wires to the other pair speakers.. like parallel series?


Now for facts. You cannot replace four 16 ohm speakers with four 8 ohm
speakers and replicate the overall impedances you had before - it
simply won't happen, however you wire them. You need to find yourself
16 ohm replacements from somewhere.

That's my dilemna. most 10" speakers are 8 Ohm..

Look: s'pose you have all yer beer in 4 16-ounce jars. You want to
replace those with four 8-ounce jars. Fine; you can do that. But you
won't have as much beer.

Here's some fundamentals:

(1) "impedance" is approximately synonymous with "resistance". That
is, resistance to the electrical force pushing the current through the
wires. As I proofread this message I see that I will use both terms
interchangeably below.

2) resistance can be provided by many kinds of load objects. Speakers
ae load objects. Resistors are load objects. Potentiometers ("pots")
used for volume-control are variable-load objects so the resistance
varies.

(3) All amplifiers are designed to generate their maximum output power
through a specific impedance. If the impedance, or resistance, of the
speakers is too great, not so much current will get pushed through the
wires, and you will not get so much volume out of yer speakers. If the
impedance is too *low*, you can damage the amplifier (imagine yer a TV
cop, bustin' down a door just when someone inside opens it: too much
force; you go flying through, fall on yer face, and break yer nose: the
resistance of the door was not matched to the power you applied, and
OOPS, something broke.)

(4) multiple speakers (or other load objects) wired in SERIES yield a
total resistance equal to the sum of the individual resistances (8
ohmseries8ohm = 16 ohm. 2ohmseries2ohm = 4 ohm). You wire two
speakers together in series by connecting the "+" terminal of one to
the "-" terminal of the other:
----+O-----+O-----
then you wire to the power source from the two unused terminals

(5) multiple speakers wired in PARALLEL yield a total resistance equal
to the inverse of the sum of the inverses of the individual resistances
(1/8ohmparallel1/8ohm = 2/8 = 1/4 and the inverse of 1/4 is 4ohm;
1/2ohm.parallel1/2ohm = 2/2 = 1/1 and the inverse of 1/1 is 1ohm;
1/8ohmparallel1/4ohm = 1/8 + 2/8 = 3/8 and the inverse of 3/8 is
8/3ohms, aka 2&2/3ohms). You wire two speakers in parallel by
connecting the "+" of one to the "+" of the other and the "-" of one to
the "-" of the other:
-----+-----+
O O
------------
then you make a second connection from each terminal of one of the
speakers to the power source.


For yer situation, you can wire four speakers of X impedance in three
different ways:

1) Parallel.
-----+-----+-----+-----+
O O O O
------------------------
If X=8 the resistance is the inverse of 1/8 + 1/8 + 1/8 + 1/8 = 4/8,
which inverts to 8/4 or 2ohms.
If X=16 the resisance is the inverse of 1/16 + 1/16 + 1/16 + 1/16 = 4/
16, which inverts to 16/4 or 4ohms.

2) Series.
-----+O-----+O-----+O-----+O-----
If X=8 the resistance is 8+8+8+8 = 32 ohms.
If X=16 the resistance is 16+16+16+16 = 64 ohms.

3) Series/parallel (each pair is wired in parallel, then the two pairs
are put into series)
|
+-----+
O O
-------
|
+-----+
O O
-------
|
If X= 8 the resistance is the inverse of (1/8 +1/8) series (1/8 +1/8)
= 2/8 series 2/8, which inverts to 4ohms + 4ohms = 8 ohms.
If X= 16 the resistance is the inverse of (1/16 +1/16) series (1/16
+1/16) = 2/16 series 2/16 , which inverts to 8ohms + 8ohms = 16
ohms

With 8 ohm speakers you have these possibilities: (1) 2ohms, (2)
32ohms, or (3) 8ohms, of which (1) 2ohms and (3) 8ohms are suitable for
different amplifiers (Ampegs and some Carvins are optimized for 2 ohms,
for e.g.).

The original speakers allowed these possibilities: (1) 4ohms, (2) 64
ohms, or (3) 16ohms. The manufacturer chose to wire it for (1) 4ohms
and (3) 16 ohms. You can see that the manufacturer got the stereo
values by using the two parallel-wired pairs from option (3), for 8ohms
impedance each.

The upshot of all this is that you cannot store 16 ounces of beer in
one 8-ounce container.

Get 16-ohm speakers. They're out there somewhere, because there are
plenty of 4-ohm 4x10 cabinets on the market, and the only reasonable
way to get that is from 16-ohm speakers.

And don't feel bad about not knowing all this crap. You wouldn't
BELIEVE the number of times I've wanted to bid on a speaker cabinet on
eBay, but had to send a message to the seller asking the impedance. So
many musicians don't understand the importance of impedance matching,
or know how to calculate impedance, that they don't even realize that
it is an essential specificatio to list where yer trying to sell a
cabinet. On the other hand, it ain't rocket science; it's high-school
freshman algebra.


-Richard, His Kanubic Travesty
--
================================================== ====================
Richard Hopley Winston-Salem, NC, USA
.. rhopley[at]earthlink[dot]net
.. Nothing really matters except Boats, Sex, and Rock'n'Roll
.. rhopley[at]wfubmc[dot]edu
.. OK, OK; computer programming for scientific research also matters
================================================== ====================

[David Martel]

Ka,

As a novice you may wish to hit the books before you try this. You aren't
using standard terminology and so it's not clear what you want to
accomplish. If you put an 8 ohm resistor (a dummy load) in series with each
speaker then the overall resistance will become 16 ohms. You may be able to
use this "cheat" with the cabinet wiring that you have. The dummy loads must
be able to withstand the wattage that will be sent through them and about
half the amp's output will be eaten up by the dummy load so your overall
volume may be less.
Here's a link to dummy load though you may find a better price by
searching the net.
http://www.partsexpress.com/pe/showd...number=019-020
Jensen sells 16 ohm 10 in. speakers, the MOD10-35, and the MOD10-50. I
bet you can find others if you look

Dave M.

[sQuick]

"Anahata" wrote in message
...
Ka-el wrote:
[snip]

The bottom line is: however you wire them, you cannot use 4 x 8 ohm
speakers and make the combination look like 16 ohms.

If you put them all in parallel, that's 2 ohms.
If you put them all in series, it's 32 ohms.
If you put them in any series-parallel combination that distributes the
power equally between the speakers, it's 8 ohms.

With only two speakers, it's all different.
2 x 8 omhs in parallel = 4 ohms
2 x 8 ohms in series = 16 ohms

You can do the stero monitoring thing with:
Left = 2 x 8 ohms in series = 16 ohms
Right = the other 2 8 ohms in series = 16 ohms

(I'm not sure exactly what your want...)

Any combination that comes to a larger impedance than you had before is
safe to use with your amplifier, but your maximum power won't be so high.
That doesn't matter unless you were already maxing it out and it was
barely loud enough.

Maybe some part of the above will be some use to you.

Anahata

You can get round 24 Ohms by running 3 x 8 in series and parallel them up
with the other 8
would be a most bizarre set up though.

Z = Sqrt ((Z1+Z2+Z3) * (Z1+Z2+Z3) + (Z4*Z4))

So they tell me in the workshop

[[email protected]]

"Mike Rivers" wrote in message
oups.com...

Ka-eL wrote:
Hi Group!!, Novice in wiring here.. I have a Guitar Cabinet Hartke
(4x10) GH410a that has four 16 Ohms speaker, w/ 4 or 16 Ohm mono and 8
Ohm stereo switch on the input Jack.. I would like to upgrade the
speakers to four 8 Ohm.

These people will bicker forever over words and not really answer your
question. But the problem is that we don't really know what your
question is. Several people have explained how impedances combine in
series and parallel, but you won't really get any more assistance than
that until you let us know WHY you want to "upgrade" to 8 ohm speakers.
Do you just haver some 8 ohm speakers that you think sound better than
the originals?

What amplifier are you using it with? Is it a Hartke amplifier, or just
a Hartke speaker cabinet? What is the power rating and impedance of the
amplifier? If you're trying to make it louder, you may not be able to
do so. One amplifier may have its peak power at 4 ohms, while another
may have its peak power at 2 ohms, or 8 ohms, but all be called "100
watts."

Also, that stereo/mono wiring with a switch sounds pretty complicated.
Do you need to retain that capability?


Fair play Mike, Much more info is really needed to give any usable
response..

Paul..

[Oci-One Kanubi]

sQuick wrote:
"Anahata" wrote in message
...
Ka-el wrote:
[snip]

The bottom line is: however you wire them, you cannot use 4 x 8 ohm
speakers and make the combination look like 16 ohms.

If you put them all in parallel, that's 2 ohms.
If you put them all in series, it's 32 ohms.
If you put them in any series-parallel combination that distributes the
power equally between the speakers, it's 8 ohms.

With only two speakers, it's all different.
2 x 8 omhs in parallel = 4 ohms
2 x 8 ohms in series = 16 ohms

You can do the stero monitoring thing with:
Left = 2 x 8 ohms in series = 16 ohms
Right = the other 2 8 ohms in series = 16 ohms

(I'm not sure exactly what your want...)

Any combination that comes to a larger impedance than you had before is
safe to use with your amplifier, but your maximum power won't be so high.
That doesn't matter unless you were already maxing it out and it was
barely loud enough.

Maybe some part of the above will be some use to you.

Anahata

You can get round 24 Ohms by running 3 x 8 in series and parallel them up
with the other 8
would be a most bizarre set up though.

Z = Sqrt ((Z1+Z2+Z3) * (Z1+Z2+Z3) + (Z4*Z4))

So they tell me in the workshop

I do not believe that is correct. I work that out as:

Z = Sqrt((8+8+8) * (8+8+8) + (8*8))
Z = Sqrt(24*24 + 64)
Z = Sqrt(576 + 64)
Z = Sqrt(640)
z = 25.3

I believe the correct formula for calculating total resistance of
parallel loads is:
1/Z = 1/Z1 + 1/Z2 ... + 1/Zn

in this case, putting Z1, Z2, and Z3 in series, I get:
1/Z = 1/(Z1 + Z2 + Z3) + 1/Z4
1/Z = 1/(8+8+8) + 1/8
1/Z = 1/24 + 1/8
1/Z= 1/24 + 3/24
1/Z = 4/24
1/Z = 1/6
Z = 6

This is intuitively more like ly than the result I get from you
formula, because, I reason:
(a) If I have an 8 ohm resistance in parallel with a much larger
resistance, most, but not all, of the current will go through the path
of least resistance: the 8 ohm resistor.
(b) Since there is that other path that some of the current can take,
the total resistance must be less that the resistance on the 8 ohm
path, since not all the current will take the 8 ohm path.
(c) But if MOST of the current is going through the 8 ohm resistance,
and only a little is going through the other path, the total resistance
cannot be MUCH less than 8 ohms.
(d) 6 is less than 8 but not MUCH less than 8. Fortunately it did not
turn out to be 9.

The result of having an unbalanced resistance like this, though, is
that the power levels in the two paths are also unbalanced. In this
case, 3/4 of the power would go through speaker 4 and only 1/4 would go
through the other three.

The only reason to wire this way would be if one of your speakers was
rated at three (or more) times the output power of the other three.
Say you wanted to put a 100-watt 8-ohm 15" speaker in a cabinet with
three 25-watt 8-ohm 8" speakers, you would want to wire it this way so
that most of the power would take the path of least resistance through
the 15".

This is where many players go wrong; by buying two cabs without paying
any attention to the impedances. Occasionally you see a 2 ohm cab, but
most are 4 or 8. Say you have a 400-watt head optimized for 4-ohm
impedance. If you buy two cabs at different times -- even from the
same manufacturer, and sometimes even if they are the same model -- you
may be getting a 4-ohm 200-watt cab and an 8-ohm 200-watt cab. Because
the impedance is not balanced, 2/3 of the power is going to go through
the 4-ohm cab and only 1/3 through the higher-resistance cab. If you
turn you volume and gain up to 11 you will be trying to push MORE than
200 watts (more than 2/3 of yer 400-watt output) through the 4-ohm
200-watt cab.


-Richard, His Kanubic Travesty
--
================================================== ====================
Richard Hopley Winston-Salem, NC, USA
.. rhopley[at]earthlink[dot]net
.. Nothing really matters except Boats, Sex, and Rock'n'Roll
.. rhopley[at]wfubmc[dot]edu
.. OK, OK; computer programming for scientific research also matters
================================================== ====================

[Brian Running]

Hi Group!!, Novice in wiring here.. I have a Guitar Cabinet Hartke
(4x10) GH410a that has four 16 Ohms speaker, w/ 4 or 16 Ohm mono and 8
Ohm stereo switch on the input Jack.. I would like to upgrade the
speakers to four 8 Ohm.. No knowledge in impedance on speakers, but
I've heard that I need to revise my wiring? and find out what is the
total Ohm of the cabinet? w/ the switch from Mono 4-16 Ohm and Stereo 8
Ohm.. what will be my cabinet Ohm? do I need to replace the speaker
Jack inputs for 8 Ohm? I appreciate any Help!!

If the cab currently has four 16-Ohm drivers, then the switch selects
between all the drivers wired in parallel (the "4 Ohm" position), the
drivers wired in parallel/series (the "16 Ohm" position), or two sets of
two drivers with each set wired in parallel (the "stereo 8 Ohm" position).

So, if you simply swapped in 8-Ohm drivers with no other changes, your
switch would now select between 2 Ohms (the "4 Ohm" position), 8 Ohms
(the "16 Ohm" position) and 4 Ohm stereo (the "8 Ohm stereo" position).

Check your power amp's output ratings. If it shows a power output "X
Watts @ 4 Ohms", for instance, then it is capable of handling a 4-Ohm
minimum impedance. If it shows a power output "X Watts @ 8 Ohms", for
instance, then it is capable of handling an 8-Ohm minimum impedance. If
either of those is the case, then you could use your modified cabinet
with the switch in the "16 Ohm" position, but not the "4 Ohm" position.
You would only be able to use the cab with the switch in the "4 Ohm"
position if your amp has a power output rating at 2 Ohms, which is
unlikely. Even if it does, there are drawbacks to running an amp into
a 2-Ohm load, and you shouldn't do it, anyway.

So, the answer is no, you don't need to change the wiring, but you
should never use the cab with the switch in the "4 Ohm" position, and
the stereo position only if the amp is two-channel and each channel is
rated at 4 Ohms.

[Anahata]

Oci-One Kanubi wrote:

You can get round 24 Ohms by running 3 x 8 in series and parallel them up
with the other 8

I do not believe that is correct. I work that out as:

No, it isn't.

You could put 8 in series with 8 in series with (2 x 8 in parallel)
and get 20 ohms.

I did mention "equal distribution of power between the speakers" in my
original post, however, and you won't get that with such an arrangement.
Two drivers will be each running at a quarter of the power of the other
two. But it would work, FSVO "work".

Anahata

[Oci-One Kanubi]

Brian Running wrote:
snip

position if your amp has a power output rating at 2 Ohms, which is
unlikely. Even if it does, there are drawbacks to running an amp into
a 2-Ohm load, and you shouldn't do it, anyway.

This one is news to me. I have an Ampeg 5B5R and a Carvin R1000, both
of which are spec'ed out (on the back panel) to deliver maximum power
(500W and 1,000W, respectively) into a 2 ohm load. I have taken great
care to buy 4-ohm 600W cabinets so that I will have Max Headroom
available to me from a 2-cab stack (without overdriving the speakers)
or use the Ampeg with just one cab yielding ~350W at 4 ohms.

Why on earth would I want to distrust the manufacturer's specs and
settle for less potential output power by putting a 4 ohm load on an
amp rated for a 2 ohm load?

If I am jeopardizing the integrity or the life-span of my equipment by
setting up this way, I'd REALLY like to know!

br /br / font face="courier"pre
-Richard, His Kanubic Travesty
--
================================================== ====================
Richard Hopley Winston-Salem, NC, USA
.. rhopley[at]earthlink[dot]net
.. Nothing really matters except Boats, Sex, and Rock'n'Roll
.. rhopley[at]wfubmc[dot]edu
.. OK, OK; computer programming for scientific research also matters
================================================== ====================
/pre/font

[GregS]

In article om, "Oci-One Kanubi" wrote:
Brian Running wrote:
snip

position if your amp has a power output rating at 2 Ohms, which is
unlikely. Even if it does, there are drawbacks to running an amp into
a 2-Ohm load, and you shouldn't do it, anyway.

This one is news to me. I have an Ampeg 5B5R and a Carvin R1000, both
of which are spec'ed out (on the back panel) to deliver maximum power
(500W and 1,000W, respectively) into a 2 ohm load. I have taken great
care to buy 4-ohm 600W cabinets so that I will have Max Headroom
available to me from a 2-cab stack (without overdriving the speakers)
or use the Ampeg with just one cab yielding ~350W at 4 ohms.

Why on earth would I want to distrust the manufacturer's specs and
settle for less potential output power by putting a 4 ohm load on an
amp rated for a 2 ohm load?

If I am jeopardizing the integrity or the life-span of my equipment by
setting up this way, I'd REALLY like to know!

I usually go with whats spec'ed, but for some reason 2 ohms sounds scary. I
have a Peavey thats 1000 wats per channel at 2 ohms. Running an amp
at half power is really going to increase life and reliability, and you will hardly
hear any difference anyway.

If the car audio amp companies would covert some of their car amps from 12 volt DC switchers
to 120 VAC switchers, the output stages could remaine the same, and we would
have a whole ****load of low ohms powers amps on the market.

greg

[Brian Running]

If I am jeopardizing the integrity or the life-span of my equipment by
setting up this way, I'd REALLY like to know!

Running into 2 Ohms results in greater current flow (obviously, that's
why it generates more power), which results in greater heat being
generated by the amp. Heat is the enemy of every electronic component,
the more heat, the shorter the lifespan of the components. Different
manufacturers build to different standards, of course, and some of those
2-Ohm ratings are more appropriate than others, but as a general thing,
I think running at 2 Ohms oughta be avoided.

2 Ohms also results in more distortion and lower damping factor, neither
of which is probably a big concern in a musical-instrument rig.

[anahata]

Brian Running wrote:

Running into 2 Ohms results in greater current flow (obviously, that's
why it generates more power), which results in greater heat being
generated by the amp. Heat is the enemy of every electronic component,

Yes, but a 500W amplifier running at full output gererates the same
amount of heat whether that's achieved with a 2, 4 or 8 ohms load.

What's more of a specific problem with 2 ohms is that your speaker
cables had better be short and fat, or you'll lose power in them.

--
Anahata
-+- http://www.treewind.co.uk
Home: 01638 720444 Mob: 07976 263827

[Scott Dorsey]

anahata wrote:
Brian Running wrote:
Running into 2 Ohms results in greater current flow (obviously, that's
why it generates more power), which results in greater heat being
generated by the amp. Heat is the enemy of every electronic component,

Yes, but a 500W amplifier running at full output gererates the same
amount of heat whether that's achieved with a 2, 4 or 8 ohms load.

Not if it has the same series resistance inside the output devices. Think
of it as a resistive divider, with the internal resistance of the amp being
one leg and the speaker being the other. You want all the power to be
dissipated into the speaker and as little as possible being dissipated into
the interna amplifier resistances.

What's more of a specific problem with 2 ohms is that your speaker
cables had better be short and fat, or you'll lose power in them.

Also an issue. Also the damping factor is poorer (since the speaker impedance
is now closer to the actual output impedance of the amp). In a bass amp
neither one of these will be that big a deal since the cables are short
and a couple feet of #10 isn't too expensive, and the poorer damping may
even improve the bottom a little.
--scitt
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Benj]

Scott Dorsey wrote:

Not if it has the same series resistance inside the output devices. Think
of it as a resistive divider, with the internal resistance of the amp being
one leg and the speaker being the other. You want all the power to be
dissipated into the speaker and as little as possible being dissipated into
the interna amplifier resistances.

What's more of a specific problem with 2 ohms is that your speaker
cables had better be short and fat, or you'll lose power in them.

Also an issue. Also the damping factor is poorer (since the speaker impedance
is now closer to the actual output impedance of the amp). In a bass amp
neither one of these will be that big a deal since the cables are short
and a couple feet of #10 isn't too expensive, and the poorer damping may
even improve the bottom a little.

I think what Scott and everybody has said is pretty much correct,
however, there are a couple of practical reliability issues here. As
Brian more or less implies, 4 Ohms has become a kind of defacto amp
standard. What this means is that most amps have the output stages
designed to operate reliably into 4 ohms. If you you use 2 Ohms you
draw too much current and the output devices can't handle it and either
they blow or trip the protection cicuits. But some manufaturers for the
case where people may want to plug into two 4 Ohm cabs rate amps at 2
Ohms. They simply double the current capacity of the output devices.
Well and good BUT it very much depends on HOW they did that. If they
simply bought some devices with twice the current ratings of the old
ones, it drives 2 Ohms, but really it's a 4 Ohm amp in every other
respect. In this case the 2 Ohm thing is a nice feature to have for
every now and then, but it's not really a 2 Ohm amp. The other way
would be to REALLY design a 2 Ohm amp from ground up. I do believe some
high-end amps are like this. In this case issues are only those Scott
mentioned such as heavy wire and the like. In this case amp reliability
is not an issue. So what Brian says is more or less correct, namely
that you really won't get the warm fuzzies running many amps at 2 Ohms
even if they say they can do it, UNLESS it's a high-ender that has been
specifically designed for that service under heavy use. The lower
reliability comes from the fact that a 2 Ohm load runs the output
devices much closer to their rated current values than a 4 Ohm load.
And you pretty much can't tell what the actual max current rating of
the actual devices are unless you take time to look them up. Does this
make sense or am I just rambling?

Benj

[Brian Running]

Yes, but a 500W amplifier running at full output gererates the same
amount of heat whether that's achieved with a 2, 4 or 8 ohms load.

Sure, but the minimum-impedance rating of the amp is based upon the
amount of heat the wiring and output devices can handle. The reason
some amps are rated to handle a 2-Ohm minimum load is because they are
deemed to have wiring and devices beefy enough not to melt from the
heat. If you have an amp that's rated to handle a 2-Ohm load, then at 4
Ohms you are within a nice, comfy safety margin. If you're running into
2 Ohms specifically to take the amp to within an inch of its design
capacity, then you're going to place more thermal stress on it, plain
and simple. In other words, not running at 2 Ohms keeps you from
achieving the amp's full output and keeps you well away from any
heat-related issues.

I used to run a Peavey T-Max bass amp into a 2-Ohm load created by two
4-Ohm cabinets. It got the full 500 Watts out of it, but the top of
that amp was hotter than hell. That's just not good for electronics.
Running a two-channel amp into two separate 4-Ohm loads keeps everything
cooler. Cooler is better.

[liquidator]

"Oci-One Kanubi" wrote in message
ps.com...
Brian Running wrote:
snip

position if your amp has a power output rating at 2 Ohms, which is
unlikely. Even if it does, there are drawbacks to running an amp into
a 2-Ohm load, and you shouldn't do it, anyway.

This one is news to me. I have an Ampeg 5B5R and a Carvin R1000, both
of which are spec'ed out (on the back panel) to deliver maximum power
(500W and 1,000W, respectively) into a 2 ohm load. I have taken great
care to buy 4-ohm 600W cabinets so that I will have Max Headroom
available to me from a 2-cab stack (without overdriving the speakers)
or use the Ampeg with just one cab yielding ~350W at 4 ohms.

Why on earth would I want to distrust the manufacturer's specs and
settle for less potential output power by putting a 4 ohm load on an
amp rated for a 2 ohm load?

If I am jeopardizing the integrity or the life-span of my equipment by
setting up this way, I'd REALLY like to know!



As far as jeopardizing the equipment, I doubt it.

But many amps are rated differently at 2 ohms. I've seen tons of amps rated
full bandwidth at 4 but rated at 1 khz at 2 ohms.

Most amps will not aound as good at full power into the 2 ohm load. The
question then becomes- are you running it at full power.

Response generally drops off at the low and high extremes running into lower
impedance loads.

Your amps wouldn't have to carry any FTC type of rating, being instrument
amps. Car stereo stuff doesn't either- witness the "2000 watt" car stereo
amps that may not even be 100 watts. You'd have to do a good bench test to
see how they really respond.



--
Posted via a free Usenet account from http://www.teranews.com

[Ka-eL]

Brian Running wrote:
If the cab currently has four 16-Ohm drivers, then the switch selects
between all the drivers wired in parallel (the "4 Ohm" position), the
drivers wired in parallel/series (the "16 Ohm" position), or two sets of
two drivers with each set wired in parallel (the "stereo 8 Ohm" position).
So, if you simply swapped in 8-Ohm drivers with no other changes, your
switch would now select between 2 Ohms (the "4 Ohm" position), 8 Ohms
(the "16 Ohm" position) and 4 Ohm stereo (the "8 Ohm stereo" position).

I was told the same thing.. that Stereo monitoring switch really
complicating.
On this Link http://colomar.com/Shavano/4x12wiring.html
find this option Mono/Stereo in same cabinet..
What do you think if I go on the option ?


Check your power amp's output ratings. If it shows a power output "X
Watts @ 4 Ohms", for instance, then it is capable of handling a 4-Ohm
minimum impedance. If it shows a power output "X Watts @ 8 Ohms", for
instance, then it is capable of handling an 8-Ohm minimum impedance. If
either of those is the case, then you could use your modified cabinet
with the switch in the "16 Ohm" position, but not the "4 Ohm" position.
You would only be able to use the cab with the switch in the "4 Ohm"
position if your amp has a power output rating at 2 Ohms, which is
unlikely. Even if it does, there are drawbacks to running an amp into
a 2-Ohm load, and you shouldn't do it, anyway.

My Peavy XXL Amp does have that multi Ohm output 4-8-16 Ohm

So, the answer is no, you don't need to change the wiring, but you
should never use the cab with the switch in the "4 Ohm" position, and
the stereo position only if the amp is two-channel and each channel is
rated at 4 Ohms.

I should just permanently stuck the 4 Ohm switch Really appreciate
your help Thanks!!

[Ka-eL]

Mike Rivers wrote:

These people will bicker forever over words and not really answer your
question. But the problem is that we don't really know what your
question is. Several people have explained how impedances combine in
series and parallel, but you won't really get any more assistance than
that until you let us know WHY you want to "upgrade" to 8 ohm speakers.
Do you just haver some 8 ohm speakers that you think sound better than
the originals?

Thanks for your reply.. I started to get a headache just reading all
the inputs
My problem is No low-end at all my 4x10 Hartke guitar cabinet.. my
amp is a Peavy XXL
which sounds better on my Buddy's Marshall cabinet..

What amplifier are you using it with? Is it a Hartke amplifier, or just
a Hartke speaker cabinet? What is the power rating and impedance of the
amplifier? If you're trying to make it louder, you may not be able to
do so. One amplifier may have its peak power at 4 ohms, while another
may have its peak power at 2 ohms, or 8 ohms, but all be called "100
watts."

Just wanna get some more rumble or bass on my Amp.. I was told the
Stock Celestion
on the Hartke GH410a cabinet is crap ?

Also, that stereo/mono wiring with a switch sounds pretty complicated.
Do you need to retain that capability?

I would like to retain that Stereo monitoring switch, but whichever
way that works w/ four 8 Ohms speakers is fine.

[anahata]

Scott Dorsey wrote:

Yes, but a 500W amplifier running at full output gererates the same
amount of heat whether that's achieved with a 2, 4 or 8 ohms load.


Not if it has the same series resistance inside the output devices.

I take your point, but I'm suggesting or assuming that an amplifier
rated at 500W into 2 ohms will have lower output device resistances than
a different amplifier rated at 500 W into 8 ohms. I agree that the same
amplifier will become less efficient into a lower impedance load (which
is what I think you're saying), and also with the earlier poster's
implication that running any amplifier at full rated power isn't the
most reliable policy.

I was pedantically objecting to the assertion that heat was only about
current, whereas it's really about power.

--
Anahata
-+- http://www.treewind.co.uk
Home: 01638 720444 Mob: 07976 263827

[Mike Rivers]

Ka-el wrote:

Thanks for your reply.. I started to get a headache just reading all
the inputs
My problem is No low-end at all my 4x10 Hartke guitar cabinet.. my
amp is a Peavy XXL
which sounds better on my Buddy's Marshall cabinet..

Just wanna get some more rumble or bass on my Amp.. I was told the
Stock Celestion
on the Hartke GH410a cabinet is crap ?

OK, that clarifies things and puts me squarely out of a position to
give you a good answer. I'm reading your cross-posted message in
rec.audio.pro and I don't know specifics about speakers for bass
amplifiers. But I can tell you this - the impedance of the speaker
doesn't affect the bass response. That's a function of the speaker's
mechanical design and how it interacts with the cabinet. If the bass
gurus have a specific speaker in mind that will give you the sound
you're seeking, then you can worry about how to best wire up four of
them to get the most power out of your amplifier. If you don't have the
optimum impedance match, worst case is that you won't get it as loud as
it could be - but then you shouldn't have to play it at "eleven."

Unless someone has given you a set of the ideal speakers, you may find
that you'll come out better if you just get a new cabinet (with
speakers) that sounds good with your bass and amplifier, then sell your
Hartke cabinet. I wouldn't think that a 4x10 design would be
particualrly good for rumbling bass, but would be fine for some of the
detailed styles that modern bassists play - in other words, you just
have the wrong equipment for the sound you want.

Given that there's a fair amount of interaction between the speaker and
the cabinet, just changing the speaker won't necessarily give you a
predictable sound. Better to look for a complete assembly that sounds
the way you want it to sound. Alternatively, if you're willing ot
experiment with speakers, don't worry about impedance matching. Get it
as close as you can when you find a sound you like.

[Mike Rivers]

Ka-el wrote:

My Peavy XXL Amp does have that multi Ohm output 4-8-16 Ohm

It's not clear how this switch works (no schematic available). It could
switch taps on a transformer, or it could just be a trick. However, you
can wire four 8-ohm speakers in parallel which gets you 2 ohms, and
that's not recommended by Peavey. You can also wire them to get 8 ohms
by putting two parallel pairs in series, or two series pairs in
parallel. Speaker purists will argue advantages and disadvantages of
each based on speaker damping. So if the amplifier's impedance switch
is for real, you can match them to the amplifier by setting the switch
to 8 ohms.

In your cabinet's stereo mode, you can have either two 4 ohm pairs or
two 16 ohm pairs. However, since your amplifier doesn't have a stereo
output (the two jacks are in parallel) there's only one logical reason
to do this, and that's if you want to use that cabinet with some other
amplifier that does have two channels (or with two amplfiers). But then
you're getting into a different sound because you'll be using those
speakers with another amplifier.

So, again, I think you're looking at the wrong solution to the problem
of not liking the sound of your bass when you play it through that
cabinet with that amplifier.

[suds mcduff]

Oci-One Kanubi wrote:
Lord Vader wrote:
Don Pearce wrote:

First question. What does w/ mean?

"W/" is short for "With" .. Like "btw" which is "By the way"


Next question. What does half-tap (+) (-) mean?

Wires connecting the 2 speakers. hafltap the red (+) and black (-)
wires to the other pair speakers.. like parallel series?


Now for facts. You cannot replace four 16 ohm speakers with four 8 ohm
speakers and replicate the overall impedances you had before - it
simply won't happen, however you wire them. You need to find yourself
16 ohm replacements from somewhere.

That's my dilemna. most 10" speakers are 8 Ohm..

Look: s'pose you have all yer beer in 4 16-ounce jars. You want to
replace those with four 8-ounce jars. Fine; you can do that. But you
won't have as much beer.

Here's some fundamentals:

(1) "impedance" is approximately synonymous with "resistance". That
is, resistance to the electrical force pushing the current through the
wires. As I proofread this message I see that I will use both terms
interchangeably below.

2) resistance can be provided by many kinds of load objects. Speakers
ae load objects. Resistors are load objects. Potentiometers ("pots")
used for volume-control are variable-load objects so the resistance
varies.

(3) All amplifiers are designed to generate their maximum output power
through a specific impedance. If the impedance, or resistance, of the
speakers is too great, not so much current will get pushed through the
wires, and you will not get so much volume out of yer speakers. If the
impedance is too *low*, you can damage the amplifier (imagine yer a TV
cop, bustin' down a door just when someone inside opens it: too much
force; you go flying through, fall on yer face, and break yer nose: the
resistance of the door was not matched to the power you applied, and
OOPS, something broke.)

(4) multiple speakers (or other load objects) wired in SERIES yield a
total resistance equal to the sum of the individual resistances (8
ohmseries8ohm = 16 ohm. 2ohmseries2ohm = 4 ohm). You wire two
speakers together in series by connecting the "+" terminal of one to
the "-" terminal of the other:
----+O-----+O-----
then you wire to the power source from the two unused terminals

(5) multiple speakers wired in PARALLEL yield a total resistance equal
to the inverse of the sum of the inverses of the individual resistances
(1/8ohmparallel1/8ohm = 2/8 = 1/4 and the inverse of 1/4 is 4ohm;
1/2ohm.parallel1/2ohm = 2/2 = 1/1 and the inverse of 1/1 is 1ohm;
1/8ohmparallel1/4ohm = 1/8 + 2/8 = 3/8 and the inverse of 3/8 is
8/3ohms, aka 2&2/3ohms). You wire two speakers in parallel by
connecting the "+" of one to the "+" of the other and the "-" of one to
the "-" of the other:
-----+-----+
O O
------------
then you make a second connection from each terminal of one of the
speakers to the power source.


For yer situation, you can wire four speakers of X impedance in three
different ways:

1) Parallel.
-----+-----+-----+-----+
O O O O
------------------------
If X=8 the resistance is the inverse of 1/8 + 1/8 + 1/8 + 1/8 = 4/8,
which inverts to 8/4 or 2ohms.
If X=16 the resisance is the inverse of 1/16 + 1/16 + 1/16 + 1/16 = 4/
16, which inverts to 16/4 or 4ohms.

2) Series.
-----+O-----+O-----+O-----+O-----
If X=8 the resistance is 8+8+8+8 = 32 ohms.
If X=16 the resistance is 16+16+16+16 = 64 ohms.

3) Series/parallel (each pair is wired in parallel, then the two pairs
are put into series)
|
+-----+
O O
-------
|
+-----+
O O
-------
|
If X= 8 the resistance is the inverse of (1/8 +1/8) series (1/8 +1/8)
= 2/8 series 2/8, which inverts to 4ohms + 4ohms = 8 ohms.
If X= 16 the resistance is the inverse of (1/16 +1/16) series (1/16
+1/16) = 2/16 series 2/16 , which inverts to 8ohms + 8ohms = 16
ohms

With 8 ohm speakers you have these possibilities: (1) 2ohms, (2)
32ohms, or (3) 8ohms, of which (1) 2ohms and (3) 8ohms are suitable for
different amplifiers (Ampegs and some Carvins are optimized for 2 ohms,
for e.g.).

The original speakers allowed these possibilities: (1) 4ohms, (2) 64
ohms, or (3) 16ohms. The manufacturer chose to wire it for (1) 4ohms
and (3) 16 ohms. You can see that the manufacturer got the stereo
values by using the two parallel-wired pairs from option (3), for 8ohms
impedance each.

The upshot of all this is that you cannot store 16 ounces of beer in
one 8-ounce container.

Get 16-ohm speakers. They're out there somewhere, because there are
plenty of 4-ohm 4x10 cabinets on the market, and the only reasonable
way to get that is from 16-ohm speakers.

And don't feel bad about not knowing all this crap. You wouldn't
BELIEVE the number of times I've wanted to bid on a speaker cabinet on
eBay, but had to send a message to the seller asking the impedance. So
many musicians don't understand the importance of impedance matching,
or know how to calculate impedance, that they don't even realize that
it is an essential specificatio to list where yer trying to sell a
cabinet. On the other hand, it ain't rocket science; it's high-school
freshman algebra.


-Richard, His Kanubic Travesty

-----Excellent post, sir, you may have a career in the "......for
Dummies" franchise. Yours was one of the easiest to understand
explanations of impedence I've read lately.
Tim T

[Scott Dorsey]

anahata wrote:
I take your point, but I'm suggesting or assuming that an amplifier
rated at 500W into 2 ohms will have lower output device resistances than
a different amplifier rated at 500 W into 8 ohms.

This isn't a good assumption to make. In fact, the two could even be the
same amplifier!

A typical amplifier rated at 500W into 8 ohms should also be rated 2000W
into 2 ohms, and therefore ought to have _lower_ device resistance than
an amplifier rated at 500W into 2 ohms.

Unfortunately many don't. Which is why a lot of amplifiers rated 500W
into 8 ohms are only rated 1500W into 2 ohms... where is that other 500W
going?
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Brian Running]

(3) All amplifiers are designed to generate their maximum output power
through a specific impedance.

Except for solid-state amplifiers, which constitute the vast majority of
power amps out there.

Get 16-ohm speakers. They're out there somewhere, because there are
plenty of 4-ohm 4x10 cabinets on the market, and the only reasonable
way to get that is from 16-ohm speakers.

Except for series/parallel wiring of 4-Ohm drivers, which is the way
that 100% of four-by speaker cabinets are wired. Hell of a lot easier
to find 4-Ohm drivers than 16. I have never seen a 4-Ohm, four-by cab
that uses 16-Ohm drivers.

[Nigel Goodwin]

In message , Scott Dorsey
writes
anahata wrote:
I take your point, but I'm suggesting or assuming that an amplifier
rated at 500W into 2 ohms will have lower output device resistances than
a different amplifier rated at 500 W into 8 ohms.

This isn't a good assumption to make. In fact, the two could even be the
same amplifier!

A typical amplifier rated at 500W into 8 ohms should also be rated 2000W
into 2 ohms, and therefore ought to have _lower_ device resistance than
an amplifier rated at 500W into 2 ohms.

Unfortunately many don't. Which is why a lot of amplifiers rated 500W
into 8 ohms are only rated 1500W into 2 ohms... where is that other 500W
going?

It's not down to output 'resistance' (should be impedance anyway), it's
mostly down to the power supply that can't supply enough power. The
output impedance of transistor amplifiers is extremely low, tiny
fractions of an ohm.
--
Nigel Goodwin
C.Farmer Ltd.
Matlock

[Brian Running]

I was pedantically objecting to the assertion that heat was only about
current, whereas it's really about power.

Heat is about current. Current is the flow of electrons, and it is the
physical flow of electrons that causes the heat. Conductors and devices
are rated for current flow, not for power, because current is the actual
physical phenomenon that generates the heat.

[S&y]

Ka-el wrote:
Mike Rivers wrote:


These people will bicker forever over words and not really answer your
question. But the problem is that we don't really know what your
question is. Several people have explained how impedances combine in
series and parallel, but you won't really get any more assistance than
that until you let us know WHY you want to "upgrade" to 8 ohm speakers.
Do you just haver some 8 ohm speakers that you think sound better than
the originals?


Thanks for your reply.. I started to get a headache just reading all
the inputs
My problem is No low-end at all my 4x10 Hartke guitar cabinet.. my
amp is a Peavy XXL
which sounds better on my Buddy's Marshall cabinet..


What amplifier are you using it with? Is it a Hartke amplifier, or just
a Hartke speaker cabinet? What is the power rating and impedance of the
amplifier? If you're trying to make it louder, you may not be able to
do so. One amplifier may have its peak power at 4 ohms, while another
may have its peak power at 2 ohms, or 8 ohms, but all be called "100
watts."


Just wanna get some more rumble or bass on my Amp.. I was told the
Stock Celestion
on the Hartke GH410a cabinet is crap ?


Also, that stereo/mono wiring with a switch sounds pretty complicated.
Do you need to retain that capability?


I would like to retain that Stereo monitoring switch, but whichever
way that works w/ four 8 Ohms speakers is fine.

Guitar cabinets are designed to suppress the low end. It isn't just the
choice of speaker. Used bass speaker cabinets are plentiful. Won't a
used cab cost as little as the retro-fit of the wrong acoustic design?

S&y

[[email protected]]

Brian Running wrote:
I was pedantically objecting to the assertion that heat was only about
current, whereas it's really about power.

Heat is about current.

Actually, no. Drop a bazillion amps through 0 ohms and, no poof!
because no heat.

Current is the flow of electrons,

Actually, no. Current is defined as the flow of charge.
It's just as much about the flow of positive charges as it
is about the flow of negative charges. Embed one of the
noble metals (palladium, platinum, etc) in hydrogen, and
protons migrate through the metal just like electrons, and
contribute just as nicely to electrical conduction.

and it is the
physical flow of electrons that causes the heat.

Actually, no. It is the thermal agitation of atoms and molecules
caused by the interruption of flow of current that is heat.

Conductors and devices
are rated for current flow, not for power, because current is the actual
physical phenomenon that generates the heat.

Actually, no. Conductors are rated for current flow over a
certain length, because it is the length and cross-section
that determine the resistance of the conductor, and it
is the current squared times that resistance, or,
completely equivalently, the voltage squared divided by
that resistance, that determines the amount of heat
generated. Consider, as a practical example, the required
rating for a 100' extension cord carrying 15 amps, and a
15 amp fuse: the cross sections are radically different,
yet they have the same current carrying capacity.

The rise in temperature is determined by the rate in which
the heat is inserted into the system vs the rate at which heat
is lost from the system. And a quick check of the fundamental
units used for these calculations reveals it to be something
called "watts." The ability, for example, of a thermal conductor
to transport heat is something called "thermal resistance"
and is measured in units of "degrees per watt."

More fundamentally: heat is a measure of the total kinetic
energy in a system. Kinetic energy is in units of power (watts)
and time (seconds). Doesn't make a hill of beans difference
whether we're talking about thermal energy (heat) or electrical
energy (watt-seconds or ergs).

Current alone is NO determing factor of heat production. The
same current through two different systems having two different
resistances will produce two different amounts of heat. Rather
it is the product of the electrical resistance and the current
squared that determines heat production.

And the product of electrical resistance and the square of
the current is called "power."

Without a single exception, you will find the heat produced
to be a direct function of power, not of current.