[Peter Larsen[_3_]]

Hi guys,

see http://muyiovatki.dk/yorkville/

comments appreciated, is the 4 Ohm box broken?

Kind regards

Peter Larsen

[Scott Dorsey]

Peter Larsen wrote:
Hi guys,

see http://muyiovatki.dk/yorkville/

comments appreciated, is the 4 Ohm box broken?

How can you have the same loudspeaker in two different impedance versions?
You change the windings on the drivers, you're going to have to change the
crossover as well and a number of other things. Pretty soon, what you have
isn't the same speaker at all.

I think what you have are two very different speakers in the same box.
--scott

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

[John Hardy]

On 7/30/2011 11:55 AM, Scott Dorsey wrote:
Peter wrote:
Hi guys,

see http://muyiovatki.dk/yorkville/

comments appreciated, is the 4 Ohm box broken?

How can you have the same loudspeaker in two different impedance versions?
You change the windings on the drivers, you're going to have to change the
crossover as well and a number of other things. Pretty soon, what you have
isn't the same speaker at all.

I think what you have are two very different speakers in the same box.
--scott

From the specs on the Yorkville page for the PL315:

Specifications subject to change without notice

John Hardy

[Dick Pierce[_2_]]

Peter Larsen wrote:
Hi guys,

see http://muyiovatki.dk/yorkville/

comments appreciated, is the 4 Ohm box broken?

Looking at one of many assertions made on the web page:

"the 4 Ohm box is less efficient, a LOT less efficient
than the 8 Ohm box. It should be 3 dB louder, not some
6 dB less loud, but that is what it is."

Having actually designed a number of drivers in 8-ohm,
4-ohm (and, for that matter, 13 ohm for one client),
this assertion makes some assumptions that simply do not
hold. For example, it assumes that the elctro-mechanical
transduction factor remains constant, it assumes mass
remains constant. Neither of these are true in designing
the same "equivalent" driver in different impedances, and
both can substantially affect voltage sensitivity.

For example, suppose you have an 8 ohm woofer and you want
to make it 4 ohms. Well, the simplest way to do it is to
simply have half the amount of wire on the voice coil.
While it will reduce the resistance by a factor of 2,
it also reduces the Bl product by factor of 2 as well.

Let's take a practical example. Suppose we start with a
17 cm woofer with a 3.8 cm, 4-layer voice coil, with a
winding length of 1.9 cm, a gap length of 0.8 cm, a
moving mass of 20 g and a compliance of 1 mm/d. We end up
with a woofer with a DC resistance of 6.8 ohm, s Bl
product of 10.2 N/A, and a reference efficiency of 0.43%.

Now, all we do is drop this to a two-layer coil. The DC
resistance drops, not surprisingly, to about 3.4 ohms,
and the BL product drops to 5.1 N/A. At the same time, we
lose about 5 grams off the voice coil, dropping the total
moving mass to 15 g. The new 4-ohm driver now has a
reference efficiency of of 0.35%, alone a drop of about
2 dB.

Now, in fact, that's not the way most designers change
efficiency: the do it by playing with a combination of
the wire gauge, number of layers, winding length and
more.

Often, to accomodate a different winding, the magnetic gap
of a 4-ohm driver has to be a bit wider. That increases the
losses in the magnet, reducing its efficiency and reducing
the flux desnity (B) in the gap.

Another issue is that the two most difficult parameters
for a manufacturer to control is sompliance and Bl product.
The latter is irrelevant here because compliance has no
appreciable effect on efficiency in the passband. But the
efficiency goes as the square of the Bl product. While the
l (length of wire in the principle portion of the magnetic
field) can be tightly controlled on a routine basis, keeping
driver-to-driver variations of the field density B is not
in the slightest bit easy. +-10% variation in high-quality
woofers is common, and that alone can account for a +-1dB
range in efficiency.

I'd be quite surprised if these two system had even
approximately the same efficiency: if they did, I'd
bet the the 8 ohm one was the broken one.

Another comment: the frequency response curves seen on the
site are , well, pretty awful, and it's mostly because of
poor measurement technique, not because of intrinsically
bad response. The curves show tremendous amount of interference
artifacts and more, and it's difficult to derive any
meaningful results from this data.

This is not a flat out criticism of whoever made the measurements
per se, but atests more to the fact that measuring speakers
properly is DAMNED hard to do. Measuring them well repeatedly
across several samples is even harder.

One and/or the other pair may well be broken. The difference
in efficiency itself is no indication of some problem. But
I'd be hard pressed to declare which was broken, if any, from
these measurements.

--
+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
+--------------------------------+

[Peter Larsen[_3_]]

John Hardy wrote:

From the specs on the Yorkville page for the PL315:

Specifications subject to change without notice



There is only a mentioning of a 4 Ohm version, there is no mentioning of
differences between 4 and 8 Ohm version, so by implication the 4 Ohm version
has the same specs as the 8 Ohm version. Also specs usually change only
during the period of manufacturing, not after.

John Hardy

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Dick Pierce wrote:

Peter Larsen wrote:
Hi guys,

see http://muyiovatki.dk/yorkville/

comments appreciated, is the 4 Ohm box broken?

Looking at one of many assertions made on the web page:

Thank you very much for the careful explanation of what can cause a "4 ohm
version of the same bass loudspeaker unit" to be less efficient, I have
altered the text on the web page in accordance with the points made.

I'd be quite surprised if these two system had even
approximately the same efficiency: if they did, I'd
bet the the 8 ohm one was the broken one.

Consistently 6 dB more sound is produced by the 8 ohm box compared to the 4
Ohm box.

Another comment: the frequency response curves seen on the
site are , well, pretty awful, and it's mostly because of
poor measurement technique, not because of intrinsically
bad response. The curves show tremendous amount of interference
artifacts and more, and it's difficult to derive any
meaningful results from this data.

Output under given conditions was measured, not frequency response per se,
it is not possible to make a valid frequency response of a large speaker in
a small room.

This is not a flat out criticism of whoever made the measurements
per se, but atests more to the fact that measuring speakers
properly is DAMNED hard to do. Measuring them well repeatedly
across several samples is even harder.

No contest.

One and/or the other pair may well be broken. The difference
in efficiency itself is no indication of some problem. But
I'd be hard pressed to declare which was broken, if any, from
these measurements.

Could well be that they are just a pro version and a toy class version of
the same speaker concept, currently I am waiting for comments from
Yorkville. It will be interesting to see whether DHL actually has lost the
second of the PL315/4's or they find it ...

Kind regards

Peter Larsen

[John Hardy]

On 7/30/2011 9:21 PM, Peter Larsen wrote:
John Hardy wrote:

From the specs on the Yorkville page for the PL315:

Specifications subject to change without notice



There is only a mentioning of a 4 Ohm version, there is no mentioning of
differences between 4 and 8 Ohm version, so by implication the 4 Ohm version
has the same specs as the 8 Ohm version. Also specs usually change only
during the period of manufacturing, not after.

John Hardy

Kind regards

Peter Larsen




From the link provided, "... comparing a PL315 bought new from a shop
in Copenhagen and a PL315/4 bought on ebay."

That could explain a lot. Is the one from Ebay new and unmodified? Is
the shop in Copenhagen an authorized dealer? When was each speaker
manufactured? Same day? Same year? My only point is, there is a plethora
of ways that differences could exist. These are discontinued speakers,
according to the manufacturer's site.

John Hardy

[Dick Pierce[_2_]]

Peter Larsen wrote:
John Hardy wrote:


From the specs on the Yorkville page for the PL315:


Specifications subject to change without notice




There is only a mentioning of a 4 Ohm version, there is no mentioning of
differences between 4 and 8 Ohm version, so by implication the 4 Ohm version
has the same specs as the 8 Ohm version.

"Implication" has no technical or legal weight. Studying the
problem purely from a technical viewpoint reveals that such
anm implication has no basis in physical fact.

From a legal standpoint, specifications are deliberately
written such that they are essentially unenforceable in
any dispute involving a purchased product.

Also specs usually change only during the period of
manufacturing, not after.

"Specifications," often written by a marketing droid in
the absence of any technical context, can and often do
change at any time for any reason. One is reminded, for
example, of the old Tektronix 5403 plug-in oscilloscope,
originally it was advertised with a bandwidth spec of 60
MHz, but, without any circuit changes that had any effect
on bandwidth, its bandwidth spec changed to 50 MHz.

Now, I have access to 3 of them: one from the first
production run and others from later, and they ALL meet
the 60 MHz bandwidth spec with room to spare. But, because
the manufacturer changed the spec (arguably retroactively),
does this imply the actual performance changed (hint:
rhetorical question)?

A "spec" is not a statement of actual performance, it is,
especially in the case of speakers, a general hint of
behavioral expectations, and deliberately loose to boot.

--
+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
+--------------------------------+

[John Hardy]

On 7/31/2011 7:52 AM, Dick Pierce wrote:
Peter Larsen wrote:
John Hardy wrote:


From the specs on the Yorkville page for the PL315:


Specifications subject to change without notice




There is only a mentioning of a 4 Ohm version, there is no mentioning
of differences between 4 and 8 Ohm version, so by implication the 4
Ohm version has the same specs as the 8 Ohm version.

"Implication" has no technical or legal weight. Studying the
problem purely from a technical viewpoint reveals that such
anm implication has no basis in physical fact.

From a legal standpoint, specifications are deliberately
written such that they are essentially unenforceable in
any dispute involving a purchased product.

Also specs usually change only during the period of
manufacturing, not after.

"Specifications," often written by a marketing droid in
the absence of any technical context, can and often do
change at any time for any reason. One is reminded, for
example, of the old Tektronix 5403 plug-in oscilloscope,
originally it was advertised with a bandwidth spec of 60
MHz, but, without any circuit changes that had any effect
on bandwidth, its bandwidth spec changed to 50 MHz.

Now, I have access to 3 of them: one from the first
production run and others from later, and they ALL meet
the 60 MHz bandwidth spec with room to spare. But, because
the manufacturer changed the spec (arguably retroactively),
does this imply the actual performance changed (hint:
rhetorical question)?

A "spec" is not a statement of actual performance, it is,
especially in the case of speakers, a general hint of
behavioral expectations, and deliberately loose to boot.


And the Titanic was "unsinkable". Etc.

John Hardy

[Peter Larsen[_3_]]

Les Cargill wrote:

When I read this, I think maybe the writer thinks that one
4 ohm version of the "same" speaker should act as if it
were two 8 ohm versions in parallel.

I am the writer. My thought was that if efficiency in watts to produce
stated spl is the same then the 4 Ohm box should be louder because the same
voltage draws twice the current. With the amplifier being a Rotel dual mono
2 X 60 watts driven in the milliwatt range it gets difficult for me to see
what would cause current not to double when load impedance is halved.

"It's 3dB louder" is only true when the amp driving them/it
is current-constrained, and even then, it's messier than
"add 3dB".

Yes, it is "all things equal" understanding I had, reading Dicks exellent
reply easily provides a couple of places where alterations involved to go
from 8 Ohms to 4 Ohms would cost a couple of dB, that price three times = 6
dB and a probable explanation to the effect that the loudspeaker "just is
like that in its 4 Ohm version" is provided.

Thanks guys!

Kind regards

Peter Larsen

[Les Cargill[_4_]]

Dick Pierce wrote:
Peter Larsen wrote:
Hi guys,

see http://muyiovatki.dk/yorkville/

comments appreciated, is the 4 Ohm box broken?

Looking at one of many assertions made on the web page:

"the 4 Ohm box is less efficient, a LOT less efficient
than the 8 Ohm box. It should be 3 dB louder, not some
6 dB less loud, but that is what it is."

snip

When I read this, I think maybe the writer thinks that one
4 ohm version of the "same" speaker should act as if it
were two 8 ohm versions in parallel.

"It's 3dB louder" is only true when the amp driving them/it
is current-constrained, and even then, it's messier than
"add 3dB".

--
Les Cargill

[William Sommerwerck]

To quote Cary Grant... "You are discussing something you know nothing
about."

This thread should have ended with the second posting.

We know nothing about the driver design, the crossover design, the bass
alignment, etc. Without that information, it's all speculation. And
speculation is almost always a waste of time. This thread is not much
different from the atrocious "Ancient Aliens" shows on The History Channel.

[Phil Allison[_3_]]

"Peter Larsen"

see http://muyiovatki.dk/yorkville/

comments appreciated, is the 4 Ohm box broken?


** From your graphs, the woofers seem close in level but there is something
fishy going on with the other two drivers.

Like you, I would expect the 4 ohm version to be about 3 dB louder in your
test - that it is not suggests to me that the drivers are non original in
the 4 ohm box. The crossovers may be faulty or modified too.

You will have to do an investigation and use an ohm meter to compare the
resistances of each driver in each box.

At a guess, the woofer is an 8 ohm replacement, the horn driver is 16 ohms
and the tweeter is burnt out.


..... Phil

[Trevor]

"William Sommerwerck" wrote in message
...
We know nothing about the driver design, the crossover design, the bass
alignment, etc.

All true, but I assume Peter expected the Driver design, Xover design, to be
very similar, but as Dick pointed out, the driver is unlikely to have
exactly the same BL product (I would have expected less than a 6dB
difference in efficiency from a reputable manufacturer however, maybe not
for white van speakers :-)
And I would hope the box design/bass alignment is the same IF the model is
supposed to be the same at least. But no guarantees there either.

Trevor.

[Phil Allison[_3_]]

"William Sommerwerck"

To quote Cary Grant... "You are discussing something you know nothing
about."

This thread should have ended with the second posting.

We know nothing about the driver design, the crossover design, the bass
alignment, etc. Without that information, it's all speculation.


** The schem of the x-over for the 8 ohm version is he

http://yorkville.com/downloads/other/smpulse.pdf

A 4 ohm version would need a 4 ohm ( nominal ) woofer, 8 ohm ( nominal)
compression driver.

The boxes are bound to be the same and ( electro /acoustic) efficiency ought
to be close to the same - ie dBs per watt per metre.

The 4 ohm version should deliver +3dB SPL if fed the same test signal.




..... Phil

[Peter Larsen[_3_]]

Phil Allison wrote:

** From your graphs, the woofers seem close in level but there is
something fishy going on with the other two drivers.

Thank you Phil, that is how it sounds and the difference in sound was what
made me measure. I am waiting for a response from Yorkville and I will call
them pr. telephone if I don't get one tomorrow.

DHL called me today, they have found the box they mislaid and will deliver
it on wednesday.

Image of the boxes added to the web site, notice the incorrect fitting of
the gray band on the 4 Ohm box, it is in front of the treble driver. See
http://www.muyiovatki.dk/yorkville

At a guess, the woofer is an 8 ohm replacement, the horn driver is 16
ohms and the tweeter is burnt out.

That would be wonderful in as much as it is a piezo and I wouldn't mind
replacing it with some bullet tweeter or diffraction tweeter and it would
then only be about getting an 8 Ohm cross-over as sparepart. But I am
beginning to wonder about magnet sizes. But I just do not have time to do a
lot of taking apart today - first day on the day job after vacation, and I
don't want to desolder an ebay purchase with acceptance pending for
impedance measurement before hearing from Yorkville. What makes me want to
"take apart" is also that I want to look at magnet sizes ..

A sane way to design the 4 Ohm box would btw. be to stick with the same
midrange and top components as in the 8 Ohm box. But there sees to be no
valid technical reason to make a 4 Ohm box for those that can't afford large
amplifiers if it ends up in toy class efficiency so that they get more sound
from the same amp by getting the 8 Ohm version.

The money side of it is however that it will cost me another GBP 160 to
refuse them and ship them back and they were cheap at GBP 225 for the pair
..... it is quite possibly just "less of a bargain".

.... Phil

I will make a summary follow up when I know more, from a technical viewpoint
is is a fascinating conundrum. One of the more extreme fixes would be to get
a set of 8 Ohm innards from Yorkville.

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Trevor wrote:

"William Sommerwerck" wrote in message
...

We know nothing about the driver design, the crossover design, the
bass alignment, etc.

Fairly well documented in the archive version of Yorkvilles web site, bass
alignment seems identical and is irrelevant as this is about one box
sounding open in the high range, and one box sounding dull.

All true, but I assume Peter expected the Driver design, Xover
design, to be very similar, but as Dick pointed out, the driver is
unlikely to have exactly the same BL product (I would have expected
less than a 6dB difference in efficiency from a reputable
manufacturer however, maybe not for white van speakers :-)

And with a bit of loss of efficiency there is no point in not leaving the
high range section "as is" since there is no problem to solve by lowering
its impedance. If efficiency goes out with the bathwater there also is not
any reason to make the 4 Ohm version in the first place, other than perhaps
saving on magnet size.

And I would hope the box design/bass alignment is the same IF the
model is supposed to be the same at least. But no guarantees there
either.

Hopefully Yorkville can explain this. I will make a summary folder up when I
know more. For me the 6 dB output difference is the difference between
outdoor vox projection to 120 meters or to 60 meters for each box.

Trevor

Kind regards

Peter Larsen

[Sean Conolly]

"Peter Larsen" wrote in message
k...
Trevor wrote:

"William Sommerwerck" wrote in message
...

We know nothing about the driver design, the crossover design, the
bass alignment, etc.

Fairly well documented in the archive version of Yorkvilles web site, bass
alignment seems identical and is irrelevant as this is about one box
sounding open in the high range, and one box sounding dull.

Has the other speaker arrived yet to compare? There may simply be a problem
with the crossover in the one you have.

Sean

[Peter Larsen[_2_]]

Sean Conolly wrote:

Has the other speaker arrived yet to compare? There may simply be a problem
with the crossover in the one you have.

DHL driver called me yesterday @daytimejob and wanted to deliver @home,
10 minutes after I had talked to their "find stuff" department who
wanted additional information about how the shipment looked as they had
not been able to find it. I had to ask him deliver it wednesday.

Sean

Kind regards

Peter Larsen

[Phil Allison[_3_]]

"Peter Larsen"

A sane way to design the 4 Ohm box would btw. be to stick with the same
midrange and top components as in the 8 Ohm box.

** Long as similar woofers and compression drivers are available in 4 and 8
ohms, that is the easiest way to do it.

( Note that the 8 ohm version uses a 16 ohm compression driver. )


But there sees to be no valid technical reason to make a 4 Ohm box for
those that can't afford large amplifiers if it ends up in toy class
efficiency so that they get more sound from the same amp by getting the 8
Ohm version.

** Obviously true.

Another way to convert any box from 8 to 4 ohms is to simply install a
matching transformer at the input, ie an auto-transformer that gives a 41%
step up in voltage.

A toroidal cored type would make it quite small and inexpensive too.

BTW

The size of the magnet does not change with rated impedance - 4, 8 and 16
ohms versions have identical magnet structures.

Speakers have been made with impedances from 0.5 ohms ( eg Bose) up to
hundreds of ohms and the only thing that changes in the gauge of the wire
wound on the voice coil.


..... Phil

[Les Cargill[_4_]]

Phil Allison wrote:
"Peter Larsen"

A sane way to design the 4 Ohm box would btw. be to stick with the same
midrange and top components as in the 8 Ohm box.

** Long as similar woofers and compression drivers are available in 4 and 8
ohms, that is the easiest way to do it.

( Note that the 8 ohm version uses a 16 ohm compression driver. )


But there sees to be no valid technical reason to make a 4 Ohm box for
those that can't afford large amplifiers if it ends up in toy class
efficiency so that they get more sound from the same amp by getting the 8
Ohm version.

** Obviously true.

Another way to convert any box from 8 to 4 ohms is to simply install a
matching transformer at the input, ie an auto-transformer that gives a 41%
step up in voltage.

A toroidal cored type would make it quite small and inexpensive too.


That seems like a free lunch. It isn't, but it seems like one
1.41 is dangerously close to sqrt(2).


BTW

The size of the magnet does not change with rated impedance - 4, 8 and 16
ohms versions have identical magnet structures.


I think that's probably true, based on what I've seen.

Speakers have been made with impedances from 0.5 ohms ( eg Bose) up to
hundreds of ohms and the only thing that changes in the gauge of the wire
wound on the voice coil.


FWIW, I have found trolling through the Eminence online catalog to be
a source of a great deal of data on loudspeakers.


.... Phil






--
Les Cargill

[Sean Conolly]

"Peter Larsen" wrote in message
...
Sean Conolly wrote:

Has the other speaker arrived yet to compare? There may simply be a
problem
with the crossover in the one you have.

DHL driver called me yesterday @daytimejob and wanted to deliver @home,
10 minutes after I had talked to their "find stuff" department who
wanted additional information about how the shipment looked as they had
not been able to find it. I had to ask him deliver it wednesday.

Also, if these are used boxes there's always the possibility that they may
have been repaired with incorrect components at some point, i.e. mixing
parts from the 8 ohm version by mistake. Speculation, but maybe something to
check on.

Sean

[Phil Allison[_3_]]

"Les Cargill"
Phil Allison wrote:

BTW

The size of the magnet does not change with rated impedance - 4, 8 and
16
ohms versions have identical magnet structures.


I think that's probably true, based on what I've seen.

Speakers have been made with impedances from 0.5 ohms ( eg Bose) up to
hundreds of ohms and the only thing that changes in the gauge of the wire
wound on the voice coil.


FWIW, I have found trolling through the Eminence online catalog to be
a source of a great deal of data on loudspeakers.


** Believe nothing you hear and only half what you see ... "



..... Phil

[Bob Urz]

On 8/1/2011 9:25 PM, Phil Allison wrote:
"Peter Larsen"

A sane way to design the 4 Ohm box would btw. be to stick with the same
midrange and top components as in the 8 Ohm box.

** Long as similar woofers and compression drivers are available in 4 and 8
ohms, that is the easiest way to do it.

( Note that the 8 ohm version uses a 16 ohm compression driver. )


But there sees to be no valid technical reason to make a 4 Ohm box for
those that can't afford large amplifiers if it ends up in toy class
efficiency so that they get more sound from the same amp by getting the 8
Ohm version.

** Obviously true.

Another way to convert any box from 8 to 4 ohms is to simply install a
matching transformer at the input, ie an auto-transformer that gives a 41%
step up in voltage.


A twist of the balance control is a much cheaper and simple way to match
efficiency in a situation where you cannot get the matched parts



A toroidal cored type would make it quite small and inexpensive too.


I have seem autoformers on permanent installs, but never have seem one
on a over the counter box for musicians internally. There would seem to
be no logical reason to add expense to a box other than to use matched
components. I have seem autoformer impedance matchers for home audio
that allows many speakers to be hooked to one amplifier. I have also
seen amps shutdown or fry if too much power is fed to one


BTW

The size of the magnet does not change with rated impedance - 4, 8 and 16
ohms versions have identical magnet structures.

Many lower end manufacturers change drivers at will on the same model of
speakers over a period of time. SO, it may not be a matter of same
basket or different Z, it could be an entirely different basket with
different magnet and voice coil size, type, or magnetic gap.

Anytime you buy an open box or factory second version of a speaker you
run the risk of internal components not being what you thought they were.

Even companies like Meyers are not immune from running model changes.
I think we were teching Broadway white Christmas awhile back and the
Sound consultants were having issues with voicing on the Meyer CQ's.
Turns out there are older and newer versions of CQ's and the components
are NOT the same and the box will not sound the same between the two
versions. The solution was to swap the one box for a CQ of the same
vintage

bob

[Krooburg Science]

On Jul 30, 8:52*am, "Peter Larsen" wrote:
Hi guys,

seehttp://muyiovatki.dk/yorkville/

comments appreciated, is the 4 Ohm box broken?

* Kind regards

* Peter Larsen

That's a lot of work for a junk speaker. Why did you want to buy
these?

- K

[Phil Allison[_3_]]

"bob Errs"

Another way to convert any box from 8 to 4 ohms is to simply install a
matching transformer at the input, ie an auto-transformer that gives a
41%
step up in voltage.


A twist of the balance control is a much cheaper and simple way to match
efficiency in a situation where you cannot get the matched parts


** ROTFL - wot a retarded moron !!!


A toroidal cored type would make it quite small and inexpensive too.


I have seem autoformers on permanent installs, but never have seem one
on a over the counter box for musicians internally.


** No one gives a flying **** about what a congenital moron like Errs has
NOT seen.

The only thing the PITA old fool ever does is produce an endless stream
of FALSE points.



..... Phil

[Peter Larsen[_3_]]

Phil Allison wrote:

"Peter Larsen"

see http://muyiovatki.dk/yorkville/

comments appreciated, is the 4 Ohm box broken?

** From your graphs, the woofers seem close in level but there is
something fishy going on with the other two drivers.

DHL found and delivered the other PL315/4 today. Like the 8 Ohm box it has a
bit too much bass, midrange and treble but a nice open sound, so this does
appear to be about a somehow broken box, measuring comes later, 4now I just
wanted to verify that it arrived OK.

.... Phil

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Peter Larsen wrote:

Phil Allison wrote:

** From your graphs, the woofers seem close in level but there is
something fishy going on with the other two drivers.

DHL found and delivered the other PL315/4 today. Like the 8 Ohm box
it has a bit too much bass, midrange and treble but a nice open
sound, so this does appear to be about a somehow broken box,
measuring comes later, 4now I just wanted to verify that it arrived
OK.

A bit of initial data: bass resistance some 2.5 Ohm, mid some 7 Ohm and
piezo some 3.3 Ohm. Bulb resistance around 1 Ohm. After opening and
assembling the deviant one its mid and treble went totally silent. Opened
rear panel for bulb access. The main cause of problems was the bulb fixture.

The bulb has small bullet on end that should match a contact surface that is
loaded by spring. That surface was not perpendicular to the bulb axis and
consequently the bulb had gone from lacking to no contact.

Finagling with the contact surface and repeatedly rotating the bulb removed
the majority of the difference between the two 4 Ohm boxes. Sound - nor
curves - are not totally identical, but making physically identical
measuring setups so exactly as required by an off-axis tweeter is
non-simple. It probably will require soldering a bypass of the
bulb-protection device to eliminate it as a cause of difference, at least
during measurement and it is a long long way from being roadworthy in my
understanding of that word.

Consequently - and with the total cost of them, shipping cost included, in
mind - I have informed the seller that I have accepted them as OK within
what they are.

The boxes are totally clean inside, conformant with the sellers description
of them as having been used for ballroom dancing and being stored inbetween.
I wonder whether they have led too silent a life ...

Opinions on replacing the piezo with a Beyma CP16, impedance curve looks
benign and there may be enough front panel real estate for it?

Peter Larsen

Kind regards

Peter Larsen

[Trevor]

"Peter Larsen" wrote in message
k...
A bit of initial data: bass resistance some 2.5 Ohm, mid some 7 Ohm and
piezo some 3.3 Ohm.

It's not a piezo, or there's something wrong with your measurement.


Bulb resistance around 1 Ohm. After opening and
assembling the deviant one its mid and treble went totally silent. Opened
rear panel for bulb access. The main cause of problems was the bulb
fixture.

The bulb has small bullet on end that should match a contact surface that
is
loaded by spring. That surface was not perpendicular to the bulb axis and
consequently the bulb had gone from lacking to no contact.

Finagling with the contact surface and repeatedly rotating the bulb
removed the majority of the difference between the two 4 Ohm boxes.
Sound - nor curves - are not totally identical, but making physically
identical measuring setups so exactly as required by an off-axis tweeter
is non-simple. It probably will require soldering a bypass of the
bulb-protection device to eliminate it as a cause of difference, at least
during measurement and it is a long long way from being roadworthy in my
understanding of that word.


I'd just replace the bulb with a soldered in polyswitch, or at least solder
the bulb instead of a socket.

Trevor.

[Phil Allison[_3_]]

"Trevor the Troll"

"Peter Larsen"

I'd just replace the bulb with a soldered in polyswitch,


** Bad idea.

Incandescent bulbs provide a better solution for live sound apps.

They allow all transients and normal levels through and rapidly compresses
( without distortion ) exceptional levels - like feedback howls - to a
tolerable level for the HF drivers.

OTOH, a Polyswitch cuts the sound almost right off ( without any warning)
and takes quite a while to re-set after tripping.



..... Phil

[Trevor]

"Phil Allison" wrote in message
...
Incandescent bulbs provide a better solution for live sound apps.

They allow all transients and normal levels through and rapidly compresses
( without distortion ) exceptional levels - like feedback howls - to a
tolerable level for the HF drivers.

OTOH, a Polyswitch cuts the sound almost right off ( without any warning)
and takes quite a while to re-set after tripping.


Having replaced bulbs in others PA speakers that NEVER "reset", I don't see
that as a better problem. I already use a compressor/peak limiter and don't
need a globe to do it. And of course, rapid compression IS distortion, just
the lesser of two evils.
But as I said, át least solder the globe rather than use a socket. IF you
expect it to blow regularly enough to need one, then you've chosen the wrong
globe for the application.

Trevor.

[Phil Allison[_3_]]

"Trevor the ****wit Troll"





"Phil Allison"

I'd just replace the bulb with a soldered in polyswitch,



** ****ing Bad Idea.


Incandescent bulbs provide a better solution for live sound apps.

**They allow all transients and normal levels through and rapidly
compresses ( without distortion ) exceptional levels - like feedback
howls - to a tolerable level for the HF drivers.

OTOH, a Polyswitch cuts the sound almost right off ( without any
warning) and takes quite a while to re-set after tripping.


Having replaced bulbs in others PA speakers that NEVER "reset", I don't
see that as a better problem.


** Only proves you are STILL a ****ing, autistic moron of the very highest
order.


I already use a compressor/peak limiter and don't need a globe to do it.


** Got SFA to do with the example in question.

Proving YOU have no capacity to comprehend it.

Same as always.



And of course, rapid compression IS distortion


** Not in the case of incandescent bulbs.

You context shifting pile of human dung.


FYI: dear gentle readers:


The trolling usenet entity calling itself " Trevor " or what ****ing ever
is a serial, psychopathic, autistic and anencephalic **** who needs a bullet
in the head, ASAP.

Who will kindly oblige ??

He lives under a rock in Melbourne.

Along with all the other spiders........




...... Phil

[Peter Larsen[_3_]]

Trevor wrote:

"Peter Larsen" wrote in message
k...

A bit of initial data: bass resistance some 2.5 Ohm, mid some 7 Ohm
and piezo some 3.3 Ohm.

It's not a piezo, or there's something wrong with your measurement.

Or they put a parallel resistor inside it. More data coming up, from the
frequency response it idt definititely is a pieZo.

Bulb resistance around 1 Ohm.

[ccrap connection to bulb]

I'd just replace the bulb with a soldered in polyswitch,

Have you ever heard the instant pedagogic effects of such a contraption?

or at least
solder the bulb instead of a socket.

Nah, it either stays as it is or gets replaced by a piece of wire.

Trevor

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Phil Allison wrote:

I'd just replace the bulb with a soldered in polyswitch,

** Bad idea.

Incandescent bulbs provide a better solution for live sound apps.

They allow all transients and normal levels through and rapidly
compresses ( without distortion ) exceptional levels - like
feedback howls - to a tolerable level for the HF drivers.

It is less bad, agreed.

OTOH, a Polyswitch cuts the sound almost right off ( without any
warning) and takes quite a while to re-set after tripping.

The result of playing something with unexpected 40 Hz content on Celestion
RS1220 is a gunshot-like sound that scares horses.

Relative comparison of voltage sensitivity for all units:

8 ohm 9135815 4 ohm 9090530 4 ohm 9090546

treble -16.78 treble -21.62 treble -24.73

mid -34.77 mid -43.36 mid -48.2

bass -41.61 bass -42.87 bass -43.22

Input signal to box: white noise, bass units has mic 1 cm from center dome,
mid horns has mic far enough away to be clear of box edge reflections and
treble units has mic once cm away. dB values are "average loudness" with a
300 ms window as determined by CE2k. 2 conclusions are obvious: bass unit
voltage sensitivity is as predicted by Dick Pierce and both 4 Ohm boxes need
service. So this seems to have been the end of a very long winnning streak
in buying second hand equipment, win some, loose some, now gain knowledge to
offset loss.

Finally got feedback from Yorkville. Both 4 Ohm boxes suffer from
deteriorated x-over or midrange driver or mis-mounted midrange drivers or
dirty midrange drivers or "all of the above". Midrange driver gasket is
visually misplaced - protruding 3 mm into the horn - in one of them.

Next to do:

1) measure output frequency response directly from x-over
while loaded with units

2) remove midrange drivers and measure frequency response sans horns on

3) expected result: get a new version eminence screw-on and just remove the
piezos.

Voltage sensitivity of 8 and 4 ohm bass loudspeaker versions is near
identical, which is what made me not simply put the 4 Ohm PL315's in a
dumpster and move on. Midrange output from 8 Ohm box is basically linear, 4
ohm boxes are differently unlinear.

.... Phil

Kind regards

Peter Larsen

[Trevor]

"Phil the Dill Allison" wrote in message
...
** Only proves you are STILL a ****ing, autistic moron of the very
highest order.
You context shifting pile of human dung.
The trolling usenet entity calling itself " Trevor " or what ****ing
ever is a serial, psychopathic, autistic and anencephalic **** who needs a
bullet in the head, ASAP.
Who will kindly oblige ??
He lives under a rock in Melbourne.
Along with all the other spiders........


Sorry to see your meds have failed again Phil. I do hope the doctors can
find an alternative treatment for you before you are locked up for internet
stalking, and incentment to violence, which are criminal offences in
Australia.

Of course anyone else here reading your putrid attacks on all and sundry
over the years, already knows your invective really applies to yourself.

And do tell us how many times is it now you have had to change internet
providers because they ban you for breach of their usage policy? :-)

Trevor.

[Phil Allison[_3_]]

"Trevor the TROLL "

( snip insane ****e)


And do tell us how many times is it now you have had to change internet
providers because they ban you for breach of their usage policy? :-)


** As a matter of fact - just once.

Due to a vexatious complaint made by a certain Robert Morien ( aka Whack
Job Rob) - one of the biggest loonies ever seen on usenet.

And with whom YOU have a great deal in common.




..... Phil

[Trevor]

"Phil the Dill Allison" wrote in message
...
And do tell us how many times is it now you have had to change internet
providers because they ban you for breach of their usage policy? :-)


** As a matter of fact - just once.

And yet I have kill-filed at least a dozen of your accounts over the years!
And here you are back again.


Due to a vexatious complaint made by a certain Robert Morien ( aka Whack
Job Rob) - one of the biggest loonies ever seen on usenet.

So I guess we can assume that since your were dumped by the ISP, the
complaint was upheld. Anyone reading your verbal diahrea over the years
already knows who is the biggst whack job on Usenet.

Trevor.

[Phil Allison[_3_]]

" Trevor the Turd "


** As a matter of fact - just once.

And yet I have kill-filed at least a dozen of your accounts over the
years!


** Blatant lie.


Due to a vexatious complaint made by a certain Robert Morien ( aka Whack
Job Rob) - one of the biggest loonies ever seen on usenet.


And with whom YOU have a great deal in common.


So I guess ..


** Guessing is all a ****wit **** like you can you ever do.




.... Phil

[Trevor]

"Phil the dill Allison" wrote in message
...
And yet I have kill-filed at least a dozen of your accounts over the
years!


** Blatant lie.

Just as with all your stupid claims, you have no way of knowing what I have
done, my kill-file contains many of your previous aliases, and this one will
now be joining them!

Trevor.

[Phil Allison[_3_]]

"Trevor the Lying TROLL "


And yet I have kill-filed at least a dozen of your accounts over the
years!


** Blatant lie.

Just as with all your stupid claims, you have no way of knowing what I
have done,


** Many vile and evil deeds, that is for sure.

The fact is I have only ever used my own and full name on usenet, with just
three different ISPs in over 10 years.

OTOH you remain a totally secret and hidden person.

Like most ****wit TROLLs .



..... Phil