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Old 24th January 2014, 08:37 PM   #871
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Quote:
Originally Posted by tinnitusintx View Post
I've had Spectra 22's for a little over a year now but have had them sidelined for much of that time as it seemed they were not delivering the performance I was given the impression (from owner testimonials) they are capable of. I listened to them for a few months starting out first with a restored/refurbished Soundcraftsmen MA5002 then a Aragon 8008. The Aragon gave their sonic character a little more meat but I still found they couldn't reach SPL's beyond 85-90 db without developing what sounded like "panel slap" with LF content. I've never had the socks off and have done nothing in terms of cleaning the panels or measuring the transformers to see if bias is in spec or whatever else one might measure to ensure proper performance. It's been suggested to me to go over the panels with a blow dryer but I'd like to hear the opinions of a few others before I attempt this. Could someone please offer me a "checklist" of sorts so I can inspect and restore to best possible performance?

Oh, and I also have a pair of Threshold S/300's with one of them being the optical bias model. These have been recapped with main cap values increased to a little more than 2x the stock values as well as the rectifier upgrade and higher quality caps throughout. Not sure if the Threshold would offer much, if any, more performance than the Aragon. I can't remember if I tried the Threshold with the 22's....it's been almost a year now....but seems I did and the panel slap was still there. Having the pair of Thresholds sure makes me wish the Spectra 22's biamp capable. Can it be done?

Thanks,
Michael
Being of limited panel area, the Spectra 22/2200 does have its limits, especially in the reproduction of low frequencies. However, you may have some issues that are preventing the speaker from reaching its true potential.

The 'panel slap' may be caused by a loss of tension in the diaphragm. This can be remedied by the careful application of a hair dryer or industrial heat gun. After removing the grille socks, the panel should be vacuumed on both sides, or with care, blown out with low pressure compressed air. The re-shrinking of the mylar can be done from the front side only, by slowly and continuously moving the hot air over the entire surface of the panel. This process may take several tries before it's effective, but it's better to approach this process slowly rather than appying too much heat at once.

Measuring the bias voltage is not easy, but see my comments in another post made today. However, it's not likely to be the cause of panel-slap, nor is it likely that both speakers are suffering from low bias to the same degree. So unless one speaker is playing louder than the other, bias voltage is probably not an issue for you.

Your choice of amplifier will make a difference in the final performance of the speaker, but is not likely to be responsible for your panel slap.

The good news is that the panel-slap will not cause any damage to the Acoustat speakers (that's not necessarily true for other ESL brands) but it can be very annoying. It may be that you are merely reaching the dynamic limit of the speaker, especially if your music had a lot of bass content. And if you are listening to movie soundtracks, which often have enormous amounts of LF content, the problem will only be worse.

If, after re-shrinking the mylar, you still experience the same problem, it may be time to invest in a companion subwoofer, which will relieve the speakers of reproducing low frequencies. This will increase the dynamic capacity of the system by a large margin.
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Old 5th February 2014, 03:03 AM   #872
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Quote:
Originally Posted by AcoustatAnswerMan View Post
Being of limited panel area, the Spectra 22/2200 does have its limits, especially in the reproduction of low frequencies. However, you may have some issues that are preventing the speaker from reaching its true potential.

The 'panel slap' may be caused by a loss of tension in the diaphragm. This can be remedied by the careful application of a hair dryer or industrial heat gun. After removing the grille socks, the panel should be vacuumed on both sides, or with care, blown out with low pressure compressed air. The re-shrinking of the mylar can be done from the front side only, by slowly and continuously moving the hot air over the entire surface of the panel. This process may take several tries before it's effective, but it's better to approach this process slowly rather than appying too much heat at once.

Measuring the bias voltage is not easy, but see my comments in another post made today. However, it's not likely to be the cause of panel-slap, nor is it likely that both speakers are suffering from low bias to the same degree. So unless one speaker is playing louder than the other, bias voltage is probably not an issue for you.

Your choice of amplifier will make a difference in the final performance of the speaker, but is not likely to be responsible for your panel slap.

The good news is that the panel-slap will not cause any damage to the Acoustat speakers (that's not necessarily true for other ESL brands) but it can be very annoying. It may be that you are merely reaching the dynamic limit of the speaker, especially if your music had a lot of bass content. And if you are listening to movie soundtracks, which often have enormous amounts of LF content, the problem will only be worse.

If, after re-shrinking the mylar, you still experience the same problem, it may be time to invest in a companion subwoofer, which will relieve the speakers of reproducing low frequencies. This will increase the dynamic capacity of the system by a large margin.
One movie soundtrack that will let you know if there is a problem is THIS ONE.

Click the image to open in full size.
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Old 5th February 2014, 04:18 AM   #873
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A friend of mine gave me an old set of 2+2's becuase he had blown up the transformers and he did not want to spend the money to try to fix them.

Because the original frames and covers were in poor condition and that they were too tall to fit into my house I decided to build my own frames and incorporate a subwoofer.

I rebuilt the interface units by having new transformers wound, capacitors, resistors and diodes replaced and incorporated a crossover to send the low bass to the subs.

Bass? yeah...I got that! ;-)


A couple of my minions attaching the panels

Click the image to open in full size.


Sliding on the socks

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Side view in my old home theater

Click the image to open in full size.


My old home theater featuring a 53" HDTV and Plasma Ball

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Old 5th February 2014, 07:51 PM   #874
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Quote:
Originally Posted by BlueKatt View Post
A friend of mine gave me an old set of 2+2's becuase he had blown up the transformers and he did not want to spend the money to try to fix them.

Because the original frames and covers were in poor condition and that they were too tall to fit into my house I decided to build my own frames and incorporate a subwoofer...
Nice rebuild job! Proof once again that old Acoustats never die, even if they need a little help, as in your case.
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Old 5th February 2014, 07:59 PM   #875
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Quote:
Originally Posted by MrAcoustat View Post
One movie soundtrack that will let you know if there is a problem is THIS ONE.
I agree. I watched that movie on my system and recall that it had very prominent LF content. Even my Spectra 4400's complained a little bit, despite being crossed-over to a subwoofer below 80 Hz. I like movies with lots of LF content, but I think some of them overdo it, leaving only a few very fine systems capable of properly reproducing it. Of course, the average sound system probably doesn't even try, so lots of folks never realize what they're missing.
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Old 7th February 2014, 12:11 AM   #876
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Is there any frequency issues with the panels on tone bursts or impulse response at certain frequencys within safe SPL limits?

I ask because I am considering a set of acoustats to try out in the future but don,t want uncontrolled ringing that points to "signature" sound at any level of uncontrolled output.

I rarely listen beyond 90 db (C weighting) but realize that spurious resonances are what they are at any level.

My understanding the acoustats required serious amplifier power and this leads me to believe they are large signal design transducers instead of small signal designs that translate to higher levels of output to produce their " magic " window of what they are

This is not to be confused with serious phase angles a low impedences at high frequency,s and current demands of amps BTW.

Were the Acoustats designed for a certain SPL window and if so what was that level?

Regards
David
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Old 7th February 2014, 01:08 AM   #877
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My 2+2's will play at ~100dB (with Moscode 600 ((300 Watts per channel)) )
104 dB if not bass heavy rock. After that the amp shuts down.
They are flat to about 30 Hz, but have a peak from 40 - 100 Hz (about 6 dB up) in my room, which is one of the reasons I added a subwoofer.

Paul
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Old 7th February 2014, 05:47 PM   #878
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Quote:
Originally Posted by AVWERK View Post
Is there any frequency issues with the panels on tone bursts or impulse response at certain frequencys within safe SPL limits?

I ask because I am considering a set of acoustats to try out in the future but don,t want uncontrolled ringing that points to "signature" sound at any level of uncontrolled output.

I rarely listen beyond 90 db (C weighting) but realize that spurious resonances are what they are at any level.

My understanding the acoustats required serious amplifier power and this leads me to believe they are large signal design transducers instead of small signal designs that translate to higher levels of output to produce their " magic " window of what they are

This is not to be confused with serious phase angles a low impedences at high frequency,s and current demands of amps BTW.

Were the Acoustats designed for a certain SPL window and if so what was that level?

Regards
David
I'm not sure I even understand some of your questions, so I won't attempt to address all of them.

But to answer the last one, regarding whether Acoustats were designed for a specific 'SPL window'. In a word, no. Acoustats can play at very low levels, while still delivering all the detail and delicacy that are the hallmark of ESL's. And they can play quite loudly (more so than many ESL's) and still deliver all the same qualities. In fact, in my opinion, they exhibit little or no change in sonic character with a large change in overall volume. And, I find them equally competent with all types of music, be it rock, classical, jazz or whatever.

Yes, the speakers do require robust amplification, but that is due to their low impedance and low efficiency. In other words, more power is required to make them play at a given volume compared to more efficient speakers. The large amount of power required should not be taken to mean that they only play loud.

My recommendation is to LISTEN to a pair and see if they deliver the sound that you want. Given proper amplification and room placement, I'm betting you won't be disappointed.
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Old 7th February 2014, 07:24 PM   #879
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Ok and thanks for responding. Not everybody puts faith in test measurements and sometimes the ear is the final and more sensitive parameter needed.

Regards
David
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Old 9th February 2014, 08:37 PM   #880
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Quote:
Originally Posted by AVWERK View Post
Is there any frequency issues with the panels on tone bursts or impulse response at certain frequencys within safe SPL limits?

I ask because I am considering a set of acoustats to try out in the future but don,t want uncontrolled ringing that points to "signature" sound at any level of uncontrolled output.

Regards
David
Ringing? I associate that with the inability of a transducer to stop motion after a signal has ceased to to be sent to it. This is partially a function of mass. Seeing how an esl speaker has incredibly low mass, this is a non issue, one of the reasons why the music sounds so startling realistic.
I have heard no issue in freq response at any volume. It is possible you can hear some but that can be due to improper setup.
I played around with the MCAAC calibration on my pio receiver when I first got my 2+2's and with room treatment and perfect angling, at every calibration point, there was not a deviation of more than 2 db. Anything under 3 db is deemed too small for the ear to perceive so you can say that these speakers can have a flat response, very impressive.I listened with my pio receiver serving as a preamp, now use a Carver C-1.
My receiver had a boost at the 50hz calibration point, so I will assume that output under that kept dropping. However, the bass that I get is just so clean and tight that I'd never want to wire in a sub (and I have an Infinity ssw 212 that I could use).Yeah, mids and highs are great, but I was shocked at how good the quality of bass was.
You really need a good amp for these. The first consideration in picking out an amp is not sound quality or specs but if it can handle low impedance loads without going poof. My Hafler XL 280 fits that bill, my just recapped NAD 208 sounds much better.
One example of the importance of handling a low load can be found earlier in this thread. Someone got some 300w per channel Emotiva mono blocks and the sound was thin, with the amps shutting down from overload. My Hafler XL280 (with just 145w per channel) can work them all night at high volumes with no complaints.
In this thread, people mention amps that they use and they all can laugh at low impedences. Amps like Hafler/Transnova are common as are other less well known makes.
The other factor is that these speakers beam and you need to sit in the sweet spot.
That can be a (in my case) a reclining chair with a spot for my microbrewed beer.
In summary, you need:
1) Acoustat speakers
2) An amp that can work these speakers
3) proper setup and room treatment
4) designated sweet spot.
I won't go into the importance of good analog sources as I do listen to CD's every now and then and they sound good.
Get all of these in place and you'll have sonic nirvana. If you can do all four of these, grab yourself some cone and dome speakers and don't listen to a properly setup acoustat system- you'll kick yourself for not going the ESL route.
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