[[email protected]]

HI im really new to this and a pretty big novice but my reciever has
two settings either 6 or 8 ohms i just got some 6 ohm center and
surround speakers off of the internet and my main speakers are 8 ohms
im trying to figure out what would be the better setting on my reciver
6 or 8 or should i just return the 6 ohm speakers and try to find some
that are 8 thanks in advance

[Eeyore]

wrote:

HI im really new to this and a pretty big novice but my reciever has
two settings either 6 or 8 ohms

That's damn odd !

Why don't you say what model it is ?

Graham

[[email protected]]

On Mar 6, 8:20 pm, Eeyore
wrote:
wrote:
HI im really new to this and a pretty big novice but my reciever has
two settings either 6 or 8 ohms

That's damn odd !

Why don't you say what model it is ?

Graham
my reciever is a pioneer VSX 515

[[email protected]]

my reciever is a pioneer VSX 515 the manuel says that they recommend
speakers of 8 ohms but can switch it to 6 ohms

thanks for the help

[Eeyore]

wrote:

Eeyore wrote:
wrote:
HI im really new to this and a pretty big novice but my reciever has
two settings either 6 or 8 ohms

That's damn odd !

Why don't you say what model it is ?

my reciever is a pioneer VSX 515

I see no mention of 6 ohms here.
http://www.pioneer.co.uk/uk/products...5-S/index.html

What does the owner's manual say ?

Graham

[[email protected]]

on page 51 of the manual it says:

Switching the speaker
impedance
We recommend using speakers of 8
Ω
with this
system, but it is possible to switch the impedance
setting if you plan to use speakers with a
6
Ω
impedance rating.
€¢ With the receiver in standby, press


STANDBY/ON
while holding down the
SPEAKER IMPEDANCE
button.
Each time you do this, you switch between the
impedance settings:
€¢
SP 6 OHM
€“ Use this setting if your
speakers are rated at 6
Ω
..
€¢
SP 8 OHM
€“ Use this setting if your
speakers are rated at 8
Ω
or more.

Gray

[Eeyore]

wrote:

on page 51 of the manual it says:

Switching the speaker
impedance
We recommend using speakers of 8
Ω
with this
system, but it is possible to switch the impedance
setting if you plan to use speakers with a
6
Ω
impedance rating.
€¢ With the receiver in standby, press


STANDBY/ON
while holding down the
SPEAKER IMPEDANCE
button.
Each time you do this, you switch between the
impedance settings:
€¢
SP 6 OHM
€“ Use this setting if your
speakers are rated at 6
Ω
.
€¢
SP 8 OHM
€“ Use this setting if your
speakers are rated at 8
Ω
or more.

Ok, I found the manual and dowloaded it.

That's very unusual.

If it troubles you, I'd select 6 ohms. It won't matter about the 8 ohm speakers.
They'll be fine on a 6 ohm setting too. It's probably to ensure the amp doesn't
overheat.

Graham

[[email protected]]

nice thanks man that was exactly what i was thinking just wanted to
check in with someone also do you think an equalizer would be good
really dont know about these things

[Barry Mann]

In .com, on 03/06/07

at 08:11 PM, said:

nice thanks man that was exactly what i was thinking just wanted to
check in with someone also do you think an equalizer would be good
really dont know about these things

What benefit would an equalizer provide for you?

In general, hooking an equalizer to a home theater receiver is not
practical. Equalizers for home systems are usually stereo (two
channels). In a home theater setup, you would want at least three
channels of equalization (all of the front channels). On your receiver
you would need to use external power amplifiers if you wanted to use an
equalizer.

The automatic acoustic calibration can accomplish much of what an
equalizer could do for you. If you want to manually tinker with the
equalization, very poor instructions on how to do this begin on page 49
of the online manual.

Unless you are a diehard equalizer fan, I recommend that you skip the
equalizer.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

[Mark D. Zacharias]

wrote:
nice thanks man that was exactly what i was thinking just wanted to
check in with someone also do you think an equalizer would be good
really dont know about these things

A six-ohm speaker is in reality a conventional eight-ohm speaker. They're
just trying to rate them a bit more accurately these days. A regular
eight-ohm model will often dip below 5 ohms near the low-frequency resonance
point anyway. The problem occurs when people try to run two sets in
parallel. Modern receivers have selectable impedance to reduce the potential
for overheating. Since the power dissipation is the product of current times
the voltage across the output devices, if that voltage is reduced, the power
dissipated in the amp (and the power transformer) is reduced compared what
it would otherwise be, even at idle. I set my Yamaha to 4 ohms even though
I'm just running headphones. Just runs cooler in my stack that way.

Mark Z.

[[email protected]]

On Mar 7, 6:34 am, "Mark D. Zacharias" wrote:

A six-ohm speaker is in reality a conventional eight-ohm speaker.

No, it's not, not if they follow any of the standards in place.

They're just trying to rate them a bit more accurately these days.
A regular eight-ohm model will often dip below 5 ohms near the
low-frequency resonance point anyway.

Wrong. The impedance is almost always at its MAXIMUM
at and near the low frequency resonance.

For most 2-way systems, the minimum in0band impedance
occurs generaly around the geometric mean between the
low frequency resonance and the crossover point. That's
typically between 200 and 300 Hz, where it approaches
the DC resistance of the woofer voice coil. A similar
minimum occurs above the crossover, as the tweeter
impedance approaches its DC resistance, ignoring
any series resistance that may be in place.

FOr reflex systems, there will be two impedance
peaks with a local minimum between that. Perhaps that's
what you might be thinking of. But the Impedance at
that minimum will exceed the DC resistance of the
woofer.

3-Way systems are more complicated, and it's not
unusual to see the impedance dip BELOW the DC
resistance in the midband.

[[email protected]]

thanks ill skip the eq and run it on 6 ohms appreciate all of your
help guys

wrote in message
oups.com...
On Mar 7, 6:34 am, "Mark D. Zacharias" wrote:

3-Way systems are more complicated, and it's not
unusual to see the impedance dip BELOW the DC
resistance in the midband.

It would be quite informative if you would explain how it's possible for the
impedance to drop below the DC resistance. Or are you referring to the DC
resistance of the driver rather than that of the complete speaker?

Thanks,

Norm Strong

[Arny Krueger]

wrote in message

wrote in message
oups.com...
On Mar 7, 6:34 am, "Mark D. Zacharias"
wrote:

3-Way systems are more complicated, and it's not
unusual to see the impedance dip BELOW the DC
resistance in the midband.

It would be quite informative if you would explain how
it's possible for the impedance to drop below the DC
resistance.

DC resistance does not include loading caused by drivers that have
capacitors in series with them.

System impedance does include loading caused by drivers that have
capacitors in series with them.

What about a system with an electrostatic tweeter whose impedance decreases
to very low levels at high frequencies

What about a system with a constant-directivity horn whose
ferequency-shapring network's impedance decreases to very low levels at high
frequencies?

[[email protected]]

On Mar 7, 3:17 pm, wrote:
wrote in message

oups.com...

On Mar 7, 6:34 am, "Mark D. Zacharias" wrote:
3-Way systems are more complicated, and it's not
unusual to see the impedance dip BELOW the DC
resistance in the midband.

It would be quite informative if you would explain how it's
possible for the impedance to drop below the DC resistance.
Or are you referring to the DC resistance of the driver rather
than that of the complete speaker?

The DC resistance of the speaker is almost always the
DC resistance of the woofer.

Be that as it may, consider 3 hypothetical drivers, a
woofer, a midrange and a tweeter. Assume, for simplicity
that each exhibits an essentially resistive impedance
of 8 ohms. Combine them with a 3-way 2nd Butterworth
crossover parallel passive ladder-type network with
crossover frequencies of, oh, 500 Hz and 4 kHz and
measure the resulting impedance. It will dip significantly
below 8 ohms in the midband, i.e., below the DC resistance
of the midrange driver, down to about 6 ohms. This is, in
essence, the midrange is running partially in parallel
with both the woofer and the tweeter.

In detail, consider the following SPICE netlist that
illustrates the problem:

LWoof 1 2 3.6MH
CWoof 2 0 28UF
RWoof 2 0 8
CMidH 1 3 28UF
LMidH 3 0 3.6MH
LMidL 3 4 0.45MH
CMidL 4 0 3.52UF
RMid 4 0 8
CTweet 1 5 3.52UF
LTweet 5 0 0.45MH
RTweet 5 0 8

And the resulting impedance, plotted every
octave, looks like:

20 8
40 8
80 8
160 8.01
320 8.07
640 7.54
1280 6.29
2560 5.92
5120 7.38
10200 7.96
20500 7.99

There are other topoologies, such as described by
Bullock, that alleviate this problem somewhat, but not
completely.

[Eeyore]

wrote:

nice thanks man that was exactly what i was thinking just wanted to
check in with someone also do you think an equalizer would be good
really dont know about these things

Do you think you *need* an 'equaliser' ?

Graham

[Eeyore]

"Mark D. Zacharias" wrote:

wrote:
nice thanks man that was exactly what i was thinking just wanted to
check in with someone also do you think an equalizer would be good
really dont know about these things

A six-ohm speaker is in reality a conventional eight-ohm speaker.

Depends how you measure the impedance.

I'm not sure you're right btw. In fact I'm fairly confident you're wrong.

Graham

[Eeyore]

"Mark D. Zacharias" wrote:

A regular eight-ohm model will often dip below 5 ohms near the low-frequency
resonance point anyway.

So a six ohm one will probably dip below 4 ohms.

What exactly is your point ?

Graham

[Mark D. Zacharias]

Eeyore wrote:
"Mark D. Zacharias" wrote:

A regular eight-ohm model will often dip below 5 ohms near the
low-frequency resonance point anyway.

So a six ohm one will probably dip below 4 ohms.

What exactly is your point ?

Graham

Well, my point was invalidated anyway since I misspoke on the impedance at
resonance, but what I was trying to say was that traditional 8-ohm ratings
have in many cases been supplanted with 6-ohm ratings, with no apparent
electrical change to the speakers themselves.

Mark Z.

[Eeyore]

"Mark D. Zacharias" wrote:

Eeyore wrote:
"Mark D. Zacharias" wrote:

A regular eight-ohm model will often dip below 5 ohms near the
low-frequency resonance point anyway.

So a six ohm one will probably dip below 4 ohms.

What exactly is your point ?

Well, my point was invalidated anyway since I misspoke on the impedance at
resonance

You meant at low frequencies.


but what I was trying to say was that traditional 8-ohm ratings
have in many cases been supplanted with 6-ohm ratings, with no apparent
electrical change to the speakers themselves.

You're mistaken.

On what basis other than speculation do you think there were no changes to the
speakers ?

Graham

wrote in message
ps.com...
On Mar 7, 3:17 pm, wrote:
wrote in message

oups.com...

On Mar 7, 6:34 am, "Mark D. Zacharias" wrote:
3-Way systems are more complicated, and it's not
unusual to see the impedance dip BELOW the DC
resistance in the midband.

It would be quite informative if you would explain how it's
possible for the impedance to drop below the DC resistance.
Or are you referring to the DC resistance of the driver rather
than that of the complete speaker?

The DC resistance of the speaker is almost always the
DC resistance of the woofer.

Be that as it may, consider 3 hypothetical drivers, a
woofer, a midrange and a tweeter. Assume, for simplicity
that each exhibits an essentially resistive impedance
of 8 ohms. Combine them with a 3-way 2nd Butterworth
crossover parallel passive ladder-type network with
crossover frequencies of, oh, 500 Hz and 4 kHz and
measure the resulting impedance. It will dip significantly
below 8 ohms in the midband, i.e., below the DC resistance
of the midrange driver, down to about 6 ohms. This is, in
essence, the midrange is running partially in parallel
with both the woofer and the tweeter.

In detail, consider the following SPICE netlist that
illustrates the problem:

LWoof 1 2 3.6MH
CWoof 2 0 28UF
RWoof 2 0 8
CMidH 1 3 28UF
LMidH 3 0 3.6MH
LMidL 3 4 0.45MH
CMidL 4 0 3.52UF
RMid 4 0 8
CTweet 1 5 3.52UF
LTweet 5 0 0.45MH
RTweet 5 0 8

And the resulting impedance, plotted every
octave, looks like:

20 8
40 8
80 8
160 8.01
320 8.07
640 7.54
1280 6.29
2560 5.92
5120 7.38
10200 7.96
20500 7.99

There are other topoologies, such as described by
Bullock, that alleviate this problem somewhat, but not
completely.

That's what I thought you were referring to, but I just wanted to make sure
we were on the same wavelength. Thanks a bunch,

Norm

[Mark D. Zacharias]

Eeyore wrote:
"Mark D. Zacharias" wrote:

Eeyore wrote:
"Mark D. Zacharias" wrote:

A regular eight-ohm model will often dip below 5 ohms near the
low-frequency resonance point anyway.

So a six ohm one will probably dip below 4 ohms.

What exactly is your point ?

Well, my point was invalidated anyway since I misspoke on the
impedance at resonance

You meant at low frequencies.


but what I was trying to say was that traditional 8-ohm ratings
have in many cases been supplanted with 6-ohm ratings, with no
apparent electrical change to the speakers themselves.

You're mistaken.

On what basis other than speculation do you think there were no
changes to the speakers ?

Graham

Because I've worked with the stuff for the past thirty years and noticed no
change other than the "nominal" rating.

Notice the word "nominal".

Mark Z.

[Eeyore]

"Mark D. Zacharias" wrote:

Eeyore wrote:
"Mark D. Zacharias" wrote:

but what I was trying to say was that traditional 8-ohm ratings
have in many cases been supplanted with 6-ohm ratings, with no
apparent electrical change to the speakers themselves.

You're mistaken.

On what basis other than speculation do you think there were no
changes to the speakers ?

Because I've worked with the stuff for the past thirty years and noticed no
change other than the "nominal" rating.

Notice the word "nominal".

For most of the last 30 years I've only ever known one make of equipment
designed for 6 ohm speakers (WEM) and they are indeed 6 ohms rather than 8.

Nominal isn't *quite* as vague a term as you like to imply.

Graham

[Mark D. Zacharias]

Eeyore wrote:
"Mark D. Zacharias" wrote:

Eeyore wrote:
"Mark D. Zacharias" wrote:

but what I was trying to say was that traditional 8-ohm ratings
have in many cases been supplanted with 6-ohm ratings, with no
apparent electrical change to the speakers themselves.

You're mistaken.

On what basis other than speculation do you think there were no
changes to the speakers ?

Because I've worked with the stuff for the past thirty years and
noticed no change other than the "nominal" rating.

Notice the word "nominal".

For most of the last 30 years I've only ever known one make of
equipment designed for 6 ohm speakers (WEM) and they are indeed 6
ohms rather than 8.

Nominal isn't *quite* as vague a term as you like to imply.

Graham

I didn't say "vague". And yes, they are closer to six ohms. That's EXACTLY
the reason for my comments. Used to be the same speakers were referred to as
eight ohms, now they are referred to as six. I measure them often enough to
have satisfied myself that it is the verbiage, not the speaker drivers, that
have changed.

Mark Z.

[Eeyore]

"Mark D. Zacharias" wrote:

Eeyore wrote:
"Mark D. Zacharias" wrote:
Eeyore wrote:
"Mark D. Zacharias" wrote:

but what I was trying to say was that traditional 8-ohm ratings
have in many cases been supplanted with 6-ohm ratings, with no
apparent electrical change to the speakers themselves.

You're mistaken.

On what basis other than speculation do you think there were no
changes to the speakers ?

Because I've worked with the stuff for the past thirty years and
noticed no change other than the "nominal" rating.

Notice the word "nominal".

For most of the last 30 years I've only ever known one make of
equipment designed for 6 ohm speakers (WEM) and they are indeed 6
ohms rather than 8.

Nominal isn't *quite* as vague a term as you like to imply.


I didn't say "vague". And yes, they are closer to six ohms. That's EXACTLY
the reason for my comments. Used to be the same speakers were referred to as
eight ohms, now they are referred to as six. I measure them often enough to
have satisfied myself that it is the verbiage, not the speaker drivers, that
have changed.

It depends entirely what frequency you measure it at. The best way would
actually be with band-limited noise I reckon.

I do not however accept that a typical 8 ohm speaker is in fact closer to 6
ohms. In fact it's an area I've taken quite an interest in wrt 'impedance
compensation' in the past and I'nt come across anything in my area of interest
that would support your assertion.

Graham

[[email protected]]

On Mar 9, 10:33 am, Eeyore
wrote:
I didn't say "vague". And yes, they are closer to six ohms.
That's EXACTLY the reason for my comments. Used to
be the same speakers were referred to as eight ohms,
now they are referred to as six. I measure them often
enough to have satisfied myself that it is the verbiage,
not the speaker drivers, that have changed.

It depends entirely what frequency you measure it at.

For all but the most trival examples, loudspeaker impedance is
not measured at any one frequency, not correctly, at any rate.

Despite all the abcking-and-forthing here on this topic, there
exist clear and unambiguous standards for determing and stating
the impedance of loudspeakers. The fact that many manufacturers
and most commentators are either unaware of or choose to ignore
them does not render them irrelevant.

For example, here's the relevant section from IEC 268-5:

7. Impedance
7.1 Rated impedance

Characteristic to be specified

The rated impedance of a loudspeaker or loudspeaker
systemis that value of a pure resistance which is to be
substitutedfor the loudspeaker or system when defining
the available electric power of the source. This is to be
specifiedby the manufacturer.

Note: The rated impedance specified by the manufacturer
normally represents the lowest value of the modulus of the
impedance in that part of the rated frequency range, where
the maximum power is to be expected, and is normally not
more than 20% higher than the lowest value of the modulus
of the impedance at any frequency within the rated
frequency range.

7.2 Impedance curve
Characteristic to be specified

Description, usually presented in the form of a graph, of
the modulus of the impedance as a function of frequency,
measured under normal working conditions.

Now, we have a common means by which we can come up with a
figure. Given that the broad average specturm of music tends to
be weighted twoards the lower midrange, that says that the
minimum impedance ABOVE resonance and BELOW the middle of the
band, i.e. 150-1000 Hz, give or take, can be taken as the
"rated" impedance of the system.

And, interestingly enough, for most systems (not all, to be
sure), that value is generally in the realm of 5-20% above the
DC resistance of the woofer.

The fact that the impedance might drop significantly below that
level at substantially higher frequencies (say 8-12 kHz) is,
under the standard, irrelevant because there's simply much less
power produced in that band under the vast majority of
circumstances.

And, if there is a LARGE discrepancy between the "rated"
impedance according to the above citation and some anomolous
behavior, the impedance curve reveals all.

But you CAN'T get there without the impedance curve. You may be
able to distill to to a single, reasonable number, but NOT
without FULL knowledge of the impedance over the full rated
bandwidth of the system.

The best way would actually be with band-limited
noise I reckon.

No, the method described above, in conjunction with an
understanding of the relevant section of the remainder of
IEC268 is best, because it is a public standard which everyone
can follow

I do not however accept that a typical 8 ohm speaker is in
fact closer to 6 ohms.

The problem being is assumption that "typical 8 ohm speaker"
has a meaningful definition. My own data, based on several
thousand measurements, suggests that while the average may meet
your criteria, the variances are large.

In fact it's an area I've taken quite an interest in wrt
'impedance compensation' in the past and I'nt come
across anything in my area of interest that would
support your assertion.

Well, despite Mr. Zacharias' earlier assumptions of low-
frequency impedance, the data I have arrayed before me,
specifically the large variances from the average, suggest your
assertion has some challenges. That's further supported by the
fact that most speaker literature is marketing spin, and an
important feature (indeed, requirement) of such spin is
single-number "figures of merit," and when it's about
marketing, facts become less important. Thus, it is not unheard
of at all to see a speaker which, by IEC268-5 sec. 7.1 (op
cite) has a rated impedance of 5.9 ohms get listed in the
brochure as "nominal 8 ohm impedance".

Let's take a real-world example: the classic AR3A. The brochure
for the AR3a (published 9/74) states quite clearly, and I quote:

Impedance: 4 ohms

Now, the ACTUAL impedance is substantially below 3.2 ohms from
78 Hz to 400 Hz, and below 3 ohms from about 85 Hz to 145 Hz.

By the criteria defined in IEC268-5 7.1, this is a 3 ohm
speaker, clear an unambiguously, because

"The rated impedance specified by the manufacturer
normally represents the lowest value of the modulus
of the impedance in that part of the rated frequency
range, where the maximum power is to be expected"

is 3 ohms, and cannot be any greater than 3.6 ohms, because:

"[it] is normally not more than 20% higher than the
lowest value of the modulus of the impedance at any
frequency within the rated frequency range."

3 ohms + 20% = 3.6 ohms, and 3.6 ohms != 4 ohms

QED

[Eeyore]

wrote:

Eeyore wrote:

I didn't say "vague". And yes, they are closer to six ohms.
That's EXACTLY the reason for my comments. Used to
be the same speakers were referred to as eight ohms,
now they are referred to as six. I measure them often
enough to have satisfied myself that it is the verbiage,
not the speaker drivers, that have changed.

It depends entirely what frequency you measure it at.

For all but the most trival examples, loudspeaker impedance is
not measured at any one frequency, not correctly, at any rate.

So why did you snip the following line of my post ?

And when trimming, do please attribute the correct poster will you ?

Graham

[[email protected]]

On Mar 9, 7:47 pm, Eeyore
wrote:
wrote:
Eeyore wrote:

I didn't say "vague". And yes, they are closer to six ohms.
That's EXACTLY the reason for my comments. Used to
be the same speakers were referred to as eight ohms,
now they are referred to as six. I measure them often
enough to have satisfied myself that it is the verbiage,
not the speaker drivers, that have changed.

It depends entirely what frequency you measure it at.

For all but the most trival examples, loudspeaker impedance is
not measured at any one frequency, not correctly, at any rate.

So why did you snip the following line of my post ?

You mean the line that said:

The best way would actually be with band-limited
noise I reckon.

Which, in fact, I DID quote later in my post, and responded to
accordingly.

And when trimming, do please attribute the correct poster
will you ?

Where did I attribute anything to you that you didn't write?
The level of attribution, "" vs "" spells it out pretty
clearly using the well-established traditions of usenet
newsgroup posting that have been in place for several
decades now.

Besides that, do you have any substantive technical
replies to the technical content of my posting? I would
be interested in your views. Specifically, given your
comment:

"it's an area I've taken quite an interest in wrt
'impedance compensation' in the past"

I am curious as to what you mean by "impedance
compensation" and whether it is something along
the lines of complex conjugate matching or something
else.