Wessel Dirksen wrote:

I have to side with both of you guys on this one. I was only paying
attention to the woofer stage considering that it was the topic of
discussion at first. But after taking a look at all of it, I have to
agree with Patrick in that the tweeter schematic as it stands could
never function in this universe by any stretch of the imagination and
must contain a typo. I did a few RS-II's in the early nineties and the
tweeter stage did not look like this, that much I can remember. (they
certainly didn't look like that when they left) LC must be switched
around.

The CL HPF ahead of the the bass speaker/s really isn't necessary.
600uF and 50Mh have an Fo = 29 Hz.

The impedance of this network will be very low at 29 Hz if the
load of the speaker is a lot higher than XL or XC at 29 Hz, which = 9.1
ohms.
Without any load of the speaker on the CL filter the L&C act as a series
resonant
and perhaps high Q filter which is virtually a short circuit at 29 Hz.
The L+C with no load connected will have a response at the output of the L
which is a
very peaked one, and the signal amplitude will be higher than the input
signal at 29 Hz.


But as an R load is added across the L of the network, the input Z of the
CL rises to 9.1 ohms when the load value = 1.414 x the load value.

Anyone wondering about this should trek out to the workshop
and use an old amp at low levels with some spare L, C and R and measure
and plot the Zin for a typical network, and watch how the variation in R
load affects the
the Zin, and the response, and measure all voltages and currents and it all
becopmes clear.
Most books and websites don't tell you what you'll get in real world terms.

Finding out my way will get the concept in ppl's minds, and maybe the
complex math
may follow, but I am quite lousy with long formulas
stretching across a page with items such as " j ", the sq.rt of -1
involved.

If the load offered by the speaker is 1.414 x XL, or in this case 12.8
ohms, the
HPF response will not have any rise above the final HF response levels just
before the cut off F
which in this case will be 29Hz, - 3dB, with 90d of phase shift.
Signals below 29 Hz will be attenuated ultimately by 12 dB/octave and will
have
an ultimate phase shift of 180d.


If RL was say 30ohms, there would be a considerable peak in the response,
so if a speaker had Z = 30 ohms
at 29 Hz, then the low bass would be boosted considerably, and in effect at
29 Hz the
LC filter would act like a step up transformer that was tuned.
IN other words, a high current would pass through the LC from amp to 0V
and dliver a highish peaked LF voltage to the woofers which
are in a box, and at 29Hz the Z offered by the speakers may well be high
due to the tuned box effects.




As far as Rdc goes in the woofer. You can't measure it directly with
the C there but as Trevor points out Rdc has secondarily become a mute
issue if you consider that the CL HP alignment filter kills any
measurable or even functional reliance on primary Rdc to the input
impedance. Rdc is probably +/- 12 ohm at the woofers.

I have a few non-toasted EMIT's laying around somewhere. One is from
this period. I'll see if I can find it and publish the impedance plot
here. It might take a few days. Busy. (unfortunately not with speakers)

The impedance looking into the ribbon tranny is what is wanted.

There is a potential problem with the adjust pots on the Infinities.
The schematic indicates the R load seen by the LC filters can change
wildly, and thus upset
the damping of the LC filters, and possibly underdamp them and give a peak
in the response where
one isn't wanted.
The best way for mid and treble level adjusts to be done is with a well
switched attenuator,
so that the resistance load across the LC circuits is maintained at a
constant level.
But I often have to remove wire wound pots used in speakers due to heat
damaged wire.
I never replace them and once I have eq'd the speaker properly
I never get complaints about speakers being too bright or too dull,
even with ppl who have terrible rooms with little soft furnishing.
Many ppl with integrated amplifiers have tone controls on them,
a blessing if one has a bright room, but no amount of
equing will really compensate an awful room.
The tone controls should never have more than +/- 8dB adjust at
50Hz and 10 kHz, so that even with full boost or cut the
phase shift is minimal, and the sound is merely better balanced.
Many modern speakers are overly bright, especially on axis,
and it as if they were designed by insecure personalities fearful that
their
product be deemed lacking detail in the audition process with other brands.

Such speakers render much digital recordings rather over the top,
so a treble cut filter with a 3 postition selection
for what is a shelving of the treble between 2kHz and 20 kHz is desirable.
Ie, when in maximum cut position, the response is a pole at
1kHz and slopes 6dB per octave to a pole at 2kHz, then is level out to 20
kHz.
The sharp drawn shape of the level change is actually quite smoothed
and just starting between 300Hz and finishing at 3 kHz, and in this way
the balance between below 1 kHz is better maintained to F above 1 kHz.
This isn't so much tone control, but tonal balancing, and users of such
shelf contour filters say "Ah, that CD is now listeanable".

Patrick Turner.





Wessel

Wessel Dirksen wrote:

. . . and then there is also that series 12.5mH "inductacap" in the
midrange circuit. Would like to get my hands on one of those.

There is really alot of humor surrounding this discussion if you take a
step back.

Nothing like a bunch of old farmers arguing over a bag of wheat.
But there is maize in the bag.

Patrick Turner.



Wessel

"Wessel Dirksen" wrote in message
ups.com...
I have to side with both of you guys on this one. I was only paying
attention to the woofer stage considering that it was the topic of
discussion at first. But after taking a look at all of it, I have to
agree with Patrick in that the tweeter schematic as it stands could
never function in this universe by any stretch of the imagination and
must contain a typo. I did a few RS-II's in the early nineties and the
tweeter stage did not look like this, that much I can remember. (they
certainly didn't look like that when they left) LC must be switched
around.

As far as Rdc goes in the woofer. You can't measure it directly with
the C there but as Trevor points out Rdc has secondarily become a mute
issue if you consider that the CL HP alignment filter kills any
measurable or even functional reliance on primary Rdc to the input
impedance. Rdc is probably +/- 12 ohm at the woofers.

I have a few non-toasted EMIT's laying around somewhere. One is from
this period. I'll see if I can find it and publish the impedance plot
here. It might take a few days. Busy. (unfortunately not with speakers)

**No need. They have a very resistive 'curve' of about 4 Ohms. No major
peaks until about 120kHz. There have been around 5 different EMITs used by
Infinity. Apart from the very early, Swiss manufactured 'Full Line' EMITS,
from the QLS1 and Q2 speakers and the more recent circular ones, all the
others are very similar.


--
Trevor Wilson
www.rageaudio.com.au

Patrick Turner schreef:
Wessel Dirksen wrote:

I have to side with both of you guys on this one. I was only paying
attention to the woofer stage considering that it was the topic of
discussion at first. But after taking a look at all of it, I have to
agree with Patrick in that the tweeter schematic as it stands could
never function in this universe by any stretch of the imagination and
must contain a typo. I did a few RS-II's in the early nineties and the
tweeter stage did not look like this, that much I can remember. (they
certainly didn't look like that when they left) LC must be switched
around.

The CL HPF ahead of the the bass speaker/s really isn't necessary.
600uF and 50Mh have an Fo = 29 Hz.

The impedance of this network will be very low at 29 Hz if the
load of the speaker is a lot higher than XL or XC at 29 Hz, which = 9.1
ohms.
Without any load of the speaker on the CL filter the L&C act as a series
resonant
and perhaps high Q filter which is virtually a short circuit at 29 Hz.
The L+C with no load connected will have a response at the output of the L
which is a
very peaked one, and the signal amplitude will be higher than the input
signal at 29 Hz.


But as an R load is added across the L of the network, the input Z of the
CL rises to 9.1 ohms when the load value = 1.414 x the load value.

Anyone wondering about this should trek out to the workshop
and use an old amp at low levels with some spare L, C and R and measure
and plot the Zin for a typical network, and watch how the variation in R
load affects the
the Zin, and the response, and measure all voltages and currents and it all
becopmes clear.
Most books and websites don't tell you what you'll get in real world terms.

Finding out my way will get the concept in ppl's minds, and maybe the
complex math
may follow, but I am quite lousy with long formulas
stretching across a page with items such as " j ", the sq.rt of -1
involved.

If the load offered by the speaker is 1.414 x XL, or in this case 12.8
ohms, the
HPF response will not have any rise above the final HF response levels just
before the cut off F
which in this case will be 29Hz, - 3dB, with 90d of phase shift.
Signals below 29 Hz will be attenuated ultimately by 12 dB/octave and will
have
an ultimate phase shift of 180d.


If RL was say 30ohms, there would be a considerable peak in the response,
so if a speaker had Z = 30 ohms
at 29 Hz, then the low bass would be boosted considerably, and in effect at
29 Hz the
LC filter would act like a step up transformer that was tuned.
IN other words, a high current would pass through the LC from amp to 0V
and dliver a highish peaked LF voltage to the woofers which
are in a box, and at 29Hz the Z offered by the speakers may well be high
due to the tuned box effects.

I think you have just technically described the intention and the
pitfalls perfectly. Although rarely textbook, you align all these
parameters and you can +/- get the extended bandwidth of a 4th order
function, where the LC must be high Q (ringing like a bell and sucking
current like a sponge) to get the peak necessary to extend the
bandwidth.

These speakers should just be modded to a normal vented bass reflex
system. The cabinet is already there, so alpha is pre-determined and a
piece of cake to measure to boot. Determine a good port mass value with
fixed alpha and you're in there; problem solved, speaker improved.

As far as those stupid L pads are concerned, I love them because good
listeners hate them. I wish they still made more speakers like that but
it seems that L pad mediated DIY filtering is long on the out, probably
since mag's have been measuring product performance and publishing it.
There's nothing quite like showing their disatrous effects on FR with
measurements and give clients the satisfaction that they could hear
this affect. Hardwiring for on-axis is the way most weant it




As far as Rdc goes in the woofer. You can't measure it directly with
the C there but as Trevor points out Rdc has secondarily become a mute
issue if you consider that the CL HP alignment filter kills any
measurable or even functional reliance on primary Rdc to the input
impedance. Rdc is probably +/- 12 ohm at the woofers.

I have a few non-toasted EMIT's laying around somewhere. One is from
this period. I'll see if I can find it and publish the impedance plot
here. It might take a few days. Busy. (unfortunately not with speakers)

The impedance looking into the ribbon tranny is what is wanted.

There is a potential problem with the adjust pots on the Infinities.
The schematic indicates the R load seen by the LC filters can change
wildly, and thus upset
the damping of the LC filters, and possibly underdamp them and give a peak
in the response where
one isn't wanted.
The best way for mid and treble level adjusts to be done is with a well
switched attenuator,
so that the resistance load across the LC circuits is maintained at a
constant level.
But I often have to remove wire wound pots used in speakers due to heat
damaged wire.
I never replace them and once I have eq'd the speaker properly
I never get complaints about speakers being too bright or too dull,
even with ppl who have terrible rooms with little soft furnishing.
Many ppl with integrated amplifiers have tone controls on them,
a blessing if one has a bright room, but no amount of
equing will really compensate an awful room.
The tone controls should never have more than +/- 8dB adjust at
50Hz and 10 kHz, so that even with full boost or cut the
phase shift is minimal, and the sound is merely better balanced.
Many modern speakers are overly bright, especially on axis,
and it as if they were designed by insecure personalities fearful that
their
product be deemed lacking detail in the audition process with other brands.

Such speakers render much digital recordings rather over the top,
so a treble cut filter with a 3 postition selection
for what is a shelving of the treble between 2kHz and 20 kHz is desirable.
Ie, when in maximum cut position, the response is a pole at
1kHz and slopes 6dB per octave to a pole at 2kHz, then is level out to 20
kHz.
The sharp drawn shape of the level change is actually quite smoothed
and just starting between 300Hz and finishing at 3 kHz, and in this way
the balance between below 1 kHz is better maintained to F above 1 kHz.
This isn't so much tone control, but tonal balancing, and users of such
shelf contour filters say "Ah, that CD is now listeanable".

Patrick Turner.





Wessel

Ok, I thought there was some disaccord over the characteristics of the
tweeter but that is also exactly what I recall. Rdc in the high 3's,
pretty resistive except for outside the passband low where they get a
bit capacitive. I had to go digging into boxes anyway.

Wessel Dirksen wrote:

Ok, I thought there was some disaccord over the characteristics of the
tweeter but that is also exactly what I recall. Rdc in the high 3's,
pretty resistive except for outside the passband low where they get a
bit capacitive. I had to go digging into boxes anyway.

But the Infinities tweeter is a ribbon, no?
Then it has a tranny.
The DCR of the actual tweeter foil is very low, and it isn't transformed,
since trannies cannot transform DC characterisics.

So the "high 3s" Rdc for the tweeter would perhaps be the DCR of the
primary of the tranny winding.
but hey, that's unlikely if the tweeter signal impedance was say 8 ohms,
since
most trannies should have less than 10% winding losses, so the
DCR of the primary of the tweeter trany should be around 0.4 ohms.
The other reflected 0.4 ohms is that of the tranny secondary DCR.
But the impedance at tweeter F can readily be transformed.
We simply need to know the measured Z of the drivers and including the
tweeter tranny

Well, someone in america needs to know so they can wheel round to West,
and fix his speakers up.

Patrick Turner.

Patrick Turner schreef:
Wessel Dirksen wrote:

Ok, I thought there was some disaccord over the characteristics of the
tweeter but that is also exactly what I recall. Rdc in the high 3's,
pretty resistive except for outside the passband low where they get a
bit capacitive. I had to go digging into boxes anyway.

But the Infinities tweeter is a ribbon, no?
Then it has a tranny.
The DCR of the actual tweeter foil is very low, and it isn't transformed,
since trannies cannot transform DC characterisics.

So the "high 3s" Rdc for the tweeter would perhaps be the DCR of the
primary of the tranny winding.
but hey, that's unlikely if the tweeter signal impedance was say 8 ohms,
since
most trannies should have less than 10% winding losses, so the
DCR of the primary of the tweeter trany should be around 0.4 ohms.
The other reflected 0.4 ohms is that of the tranny secondary DCR.
But the impedance at tweeter F can readily be transformed.
We simply need to know the measured Z of the drivers and including the
tweeter tranny

Well I have never taken the time to study the details how ribbons work.
I have never needed to really wanted to becasue I have never really
liked ribbons. (I like simple pistons) But there is no obvious tranny
involved with these EMIT's unless it's integrated into the very small
motor assembly in the rear. The impedance curve of the terminals
located on the tweeter is as Trevor and I explain above.

But that's it, i'm gonna go to town on this when I get a chance. I'm
putting taking apart a fried EMIT I have and going to embark on some
discovery. That's why I keep cindered components to begin with.

Well, someone in america needs to know so they can wheel round to West,
and fix his speakers up.

West should do with his speakers whatever he wants to do with them. He
has received a bunch of good analysis and advice. And actually the
RS-III's can sound decent if happily amplified. Simply making them 2nd
order with no other changes also solves everything as far as that goes.

I would say if you are concerned about this as I am somewhat, that
there is no real reason why any reasonably straight forward project
like this one could not practically be tackled collectively here. With
free MLS software and super cheap ($3.00) near perfect minimum phase to
40kHz condensor mic capsules available, data could be emailed, and we
would have collectively inspired others to go to town on their own. How
cool would that be? I wish the internet were around 25 years ago.

Wessel

"Patrick Turner" wrote in message
...


Wessel Dirksen wrote:

Ok, I thought there was some disaccord over the characteristics of the
tweeter but that is also exactly what I recall. Rdc in the high 3's,
pretty resistive except for outside the passband low where they get a
bit capacitive. I had to go digging into boxes anyway.

But the Infinities tweeter is a ribbon, no?

**Sort of. It uses an aluminium, printed circuit 'voice coil' on a flat
Kapton sheet. It's DCR is somewhere close to 4 Ohms.

Then it has a tranny.

**No.

The DCR of the actual tweeter foil is very low, and it isn't transformed,
since trannies cannot transform DC characterisics.

**Since it does not use a transformer, all of what you just wrote is
incorrect.


--
Trevor Wilson
www.rageaudio.com.au

Wessel Dirksen wrote:

Patrick Turner schreef:
Wessel Dirksen wrote:

Ok, I thought there was some disaccord over the characteristics of the
tweeter but that is also exactly what I recall. Rdc in the high 3's,
pretty resistive except for outside the passband low where they get a
bit capacitive. I had to go digging into boxes anyway.

But the Infinities tweeter is a ribbon, no?
Then it has a tranny.
The DCR of the actual tweeter foil is very low, and it isn't transformed,
since trannies cannot transform DC characterisics.

So the "high 3s" Rdc for the tweeter would perhaps be the DCR of the
primary of the tranny winding.
but hey, that's unlikely if the tweeter signal impedance was say 8 ohms,
since
most trannies should have less than 10% winding losses, so the
DCR of the primary of the tweeter trany should be around 0.4 ohms.
The other reflected 0.4 ohms is that of the tranny secondary DCR.
But the impedance at tweeter F can readily be transformed.
We simply need to know the measured Z of the drivers and including the
tweeter tranny

Well I have never taken the time to study the details how ribbons work.
I have never needed to really wanted to becasue I have never really
liked ribbons.

Well not all ribbons sound bad; there are some gooduns around.

Basically a ribbon is a narrow strip of thin Al foil maybe 6mm wide,
stretched between terminals for the applied voltage.
The ribbon of Al is within a N-S magnetic field and the current in the foil
makes the foil move due to magnetic action.
The Z of the Al foil is very low, just a fraction of an ohm, so a
tranny to match from 8 ohms to very low ohms is needed.

Some ribbons are made with long ribbons with several Al tracks on a plastic
strip,
and thus don't need a tranny.


(I like simple pistons) But there is no obvious tranny
involved with these EMIT's unless it's integrated into the very small
motor assembly in the rear.

That is the case with many small ribbon tweeters.

The impedance curve of the terminals
located on the tweeter is as Trevor and I explain above.

But that's it, i'm gonna go to town on this when I get a chance. I'm
putting taking apart a fried EMIT I have and going to embark on some
discovery. That's why I keep cindered components to begin with.

The Al foil is **very** delicate. Ribbons can fry very easily.




Well, someone in america needs to know so they can wheel round to West,
and fix his speakers up.

West should do with his speakers whatever he wants to do with them. He
has received a bunch of good analysis and advice. And actually the
RS-III's can sound decent if happily amplified. Simply making them 2nd
order with no other changes also solves everything as far as that goes.

I would say if you are concerned about this as I am somewhat, that
there is no real reason why any reasonably straight forward project
like this one could not practically be tackled collectively here. With
free MLS software and super cheap ($3.00) near perfect minimum phase to
40kHz condensor mic capsules available, data could be emailed, and we
would have collectively inspired others to go to town on their own. How
cool would that be? I wish the internet were around 25 years ago.

Very cool. I am happy to have relied on only myself to learn what i have,
and upon the writers of the books who preceeded the net which I happily
refrained from until what seemed like the last minute, in around 2000.
But was not the net around 25 yra ago for the elites?.
Us ordinary little people couldn't afford the puters and special things......

But we had books, patience, time, and youth....

I am concerned enough that if I stir minds from lethargy and get ppl
thinking and learning and DOING SOMETHING USEFUL i'd be quite happy.

Somebody's amplifier and speaker worries are a vehicle which can
take us on an awareness trip......

Patrick Turner.



Wessel

Trevor Wilson wrote:

"Patrick Turner" wrote in message
...


Wessel Dirksen wrote:

Ok, I thought there was some disaccord over the characteristics of the
tweeter but that is also exactly what I recall. Rdc in the high 3's,
pretty resistive except for outside the passband low where they get a
bit capacitive. I had to go digging into boxes anyway.

But the Infinities tweeter is a ribbon, no?

**Sort of. It uses an aluminium, printed circuit 'voice coil' on a flat
Kapton sheet. It's DCR is somewhere close to 4 Ohms.

Then it has a tranny.

**No.

The DCR of the actual tweeter foil is very low, and it isn't transformed,
since trannies cannot transform DC characterisics.

**Since it does not use a transformer, all of what you just wrote is
incorrect.

I don't know everything.

Many ribbons use a tranny, some don't,
like Ambience for example.

Slowly, the details about Infinity are coming out into the open sunshine.

Patrick Turner.





--
Trevor Wilson
www.rageaudio.com.au

"Patrick Turner" wrote in message
...


Trevor Wilson wrote:

"Patrick Turner" wrote in message
...


Wessel Dirksen wrote:

Ok, I thought there was some disaccord over the characteristics of the
tweeter but that is also exactly what I recall. Rdc in the high 3's,
pretty resistive except for outside the passband low where they get a
bit capacitive. I had to go digging into boxes anyway.

But the Infinities tweeter is a ribbon, no?

**Sort of. It uses an aluminium, printed circuit 'voice coil' on a flat
Kapton sheet. It's DCR is somewhere close to 4 Ohms.

Then it has a tranny.

**No.

The DCR of the actual tweeter foil is very low, and it isn't
transformed,
since trannies cannot transform DC characterisics.

**Since it does not use a transformer, all of what you just wrote is
incorrect.

I don't know everything.

**Indeed.


Many ribbons use a tranny, some don't,
like Ambience for example.

**Correct. Their ribbon is essentially the same at the Infinity EMIT, but
much larger.


Slowly, the details about Infinity are coming out into the open sunshine.

**All you need to do is ask questions. I've been servicing Infinity since
1980. I am familiar with most of their products, along with the pitfalls.


--
Trevor Wilson
www.rageaudio.com.au

Trevor Wilson wrote:

"Patrick Turner" wrote in message
...


Trevor Wilson wrote:

"Patrick Turner" wrote in message
...


Wessel Dirksen wrote:

Ok, I thought there was some disaccord over the characteristics of the
tweeter but that is also exactly what I recall. Rdc in the high 3's,
pretty resistive except for outside the passband low where they get a
bit capacitive. I had to go digging into boxes anyway.

But the Infinities tweeter is a ribbon, no?

**Sort of. It uses an aluminium, printed circuit 'voice coil' on a flat
Kapton sheet. It's DCR is somewhere close to 4 Ohms.

Then it has a tranny.

**No.

The DCR of the actual tweeter foil is very low, and it isn't
transformed,
since trannies cannot transform DC characterisics.

**Since it does not use a transformer, all of what you just wrote is
incorrect.

I don't know everything.

**Indeed.


Many ribbons use a tranny, some don't,
like Ambience for example.

**Correct. Their ribbon is essentially the same at the Infinity EMIT, but
much larger.


Slowly, the details about Infinity are coming out into the open sunshine.

**All you need to do is ask questions. I've been servicing Infinity since
1980. I am familiar with most of their products, along with the pitfalls.

But from your contributions in the thread, you show you have
a very tiny understanding of Infinity speakers.

I would never ask you any questions.

It would all too easily lead to bull****.

Patrick Turner.



--
Trevor Wilson
www.rageaudio.com.au

"Patrick Turner" wrote in message
...
****es me off too every time I see an abused (and probably traumatized)
VC. But in this case the current abuse is primarily feeding an
indulgent inductive field and not frying a VC. It sure makes the client
and yourself happy when you fix 'em up and make them better than ever
though, right?
I must say i don't get too many awkward Z speakers to fix.
But quite a few ordinary designs fail.
I just fixed a pair of Infinity Reference 20, and the
voice coil in one had buckled after it had jammed, since the coil
former is weaker under compression than tension.
The glue between the inner spider diaphragm and voice coil had
all let go on both 8" drivers.
Nothing prevents the VC from jamming in this case, and the drivers
have fairly fine tolerances.

Patrick Turner.

Wessel

It is hard to believe that Infinity would make such a blatant mistake on
their schematic. I can isolate all the speakers now and tomorrow I'm pulling
the xovr. out. BTW: Is this normal....the woofers have a coil resistance of
3.4 ohms, the mid range is the same, and the EMIT is 3.1ohms. Aren't those
#s kind of low? I been also reading about an autotransformer that can raise
the impedance of the speaker system. You put it in between the amp and the
speakers. Now that I can isolate everything, what should I do? SS for the
woofers and tube for the rest? What advantages, if any will I have? Thanks
and BTW Saturday I'll let you know if that's indeed a fuse and what's
happening with the rest of the schematic.
west

west wrote:

"Patrick Turner" wrote in message
...
****es me off too every time I see an abused (and probably traumatized)
VC. But in this case the current abuse is primarily feeding an
indulgent inductive field and not frying a VC. It sure makes the client
and yourself happy when you fix 'em up and make them better than ever
though, right?
I must say i don't get too many awkward Z speakers to fix.
But quite a few ordinary designs fail.
I just fixed a pair of Infinity Reference 20, and the
voice coil in one had buckled after it had jammed, since the coil
former is weaker under compression than tension.
The glue between the inner spider diaphragm and voice coil had
all let go on both 8" drivers.
Nothing prevents the VC from jamming in this case, and the drivers
have fairly fine tolerances.

Patrick Turner.

Wessel

It is hard to believe that Infinity would make such a blatant mistake on
their schematic. I can isolate all the speakers now and tomorrow I'm pulling
the xovr. out. BTW: Is this normal....the woofers have a coil resistance of
3.4 ohms, the mid range is the same, and the EMIT is 3.1ohms. Aren't those
#s kind of low?

That's about right for speakers with 4 ohms signal impedance in their midband.

If the bass are in series, Z will be high; if in parallel, Z is low.

If there are level pots in series with mids and treble Z is higher.



I been also reading about an autotransformer that can raise
the impedance of the speaker system. You put it in between the amp and the
speakers.

I wrote a post about that in this thread.

Now that I can isolate everything, what should I do? SS for the
woofers and tube for the rest? What advantages, if any will I have? Thanks
and BTW Saturday I'll let you know if that's indeed a fuse and what's
happening with the rest of the schematic.
west

I think the woofers are low Z at 30Hz due to the 600uF and 50mH if that is what
they have in there.
Bass Z will be low if the speakers are in parallel.

Can you manage to trace the Xover schematic?

You should, so you know where things are connected.

Patrick Turner.

Hi Westly,

In any case the fun begins now and your speakers can only get better or
stay the same. Enjoy the ride!

Your Rdc measurements for the drivers puzzle me because there seems to
once again be a seeming discrepancy in the content of the data sheet. I
assume you measured each woofer independantly and not as a network as
they are configured? If so then these are 4 ohm drivers (3.4 Rdc is a
normal 4ohm Rdc)in series. Strange is that the 4.5mH inductor has a
strange value if the x-over point is as mentioned and at 600hz it sees
a load of +/- 9 ohms (including an experienced guess on the Lvc).
Unless these are true "woofers" and have no midrange response to speak
of, the 600hz figure is puzzling since the woofers are operating almost
entirely in full space. The woofers should not have to be attenuated
much at all in their pass band. (Assuming +/- 90 db/w/m on a modern PP
10" woofer -6db for 4pi radiation)

You really need some measured data here.

Wessel

west schreef:
"Patrick Turner" wrote in message
...
****es me off too every time I see an abused (and probably traumatized)
VC. But in this case the current abuse is primarily feeding an
indulgent inductive field and not frying a VC. It sure makes the client
and yourself happy when you fix 'em up and make them better than ever
though, right?
I must say i don't get too many awkward Z speakers to fix.
But quite a few ordinary designs fail.
I just fixed a pair of Infinity Reference 20, and the
voice coil in one had buckled after it had jammed, since the coil
former is weaker under compression than tension.
The glue between the inner spider diaphragm and voice coil had
all let go on both 8" drivers.
Nothing prevents the VC from jamming in this case, and the drivers
have fairly fine tolerances.

Patrick Turner.

Wessel

It is hard to believe that Infinity would make such a blatant mistake on
their schematic. I can isolate all the speakers now and tomorrow I'm pulling
the xovr. out. BTW: Is this normal....the woofers have a coil resistance of
3.4 ohms, the mid range is the same, and the EMIT is 3.1ohms. Aren't those
#s kind of low? I been also reading about an autotransformer that can raise
the impedance of the speaker system. You put it in between the amp and the
speakers. Now that I can isolate everything, what should I do? SS for the
woofers and tube for the rest? What advantages, if any will I have? Thanks
and BTW Saturday I'll let you know if that's indeed a fuse and what's
happening with the rest of the schematic.
west

I have everything apart and will supply a schematic from observation soon on
this NG. I'll name the subject RS IIIB Part II Saga.
west

"Wessel Dirksen" wrote in message
oups.com...
Hi Westly,

In any case the fun begins now and your speakers can only get better or
stay the same. Enjoy the ride!

Your Rdc measurements for the drivers puzzle me because there seems to
once again be a seeming discrepancy in the content of the data sheet. I
assume you measured each woofer independantly and not as a network as
they are configured? If so then these are 4 ohm drivers (3.4 Rdc is a
normal 4ohm Rdc)in series. Strange is that the 4.5mH inductor has a
strange value if the x-over point is as mentioned and at 600hz it sees
a load of +/- 9 ohms (including an experienced guess on the Lvc).
Unless these are true "woofers" and have no midrange response to speak
of, the 600hz figure is puzzling since the woofers are operating almost
entirely in full space. The woofers should not have to be attenuated
much at all in their pass band. (Assuming +/- 90 db/w/m on a modern PP
10" woofer -6db for 4pi radiation)

You really need some measured data here.

Wessel

west schreef:
"Patrick Turner" wrote in message
...
****es me off too every time I see an abused (and probably
traumatized)
VC. But in this case the current abuse is primarily feeding an
indulgent inductive field and not frying a VC. It sure makes the
client
and yourself happy when you fix 'em up and make them better than
ever
though, right?
I must say i don't get too many awkward Z speakers to fix.
But quite a few ordinary designs fail.
I just fixed a pair of Infinity Reference 20, and the
voice coil in one had buckled after it had jammed, since the coil
former is weaker under compression than tension.
The glue between the inner spider diaphragm and voice coil had
all let go on both 8" drivers.
Nothing prevents the VC from jamming in this case, and the drivers
have fairly fine tolerances.

Patrick Turner.

Wessel

It is hard to believe that Infinity would make such a blatant mistake on
their schematic. I can isolate all the speakers now and tomorrow I'm
pulling
the xovr. out. BTW: Is this normal....the woofers have a coil resistance
of
3.4 ohms, the mid range is the same, and the EMIT is 3.1ohms. Aren't
those
#s kind of low? I been also reading about an autotransformer that can
raise
the impedance of the speaker system. You put it in between the amp and
the
speakers. Now that I can isolate everything, what should I do? SS for
the
woofers and tube for the rest? What advantages, if any will I have?
Thanks
and BTW Saturday I'll let you know if that's indeed a fuse and what's
happening with the rest of the schematic.
west