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Old 27th February 2014, 01:42 AM   #901
john65b is offline john65b  United States
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Delta, for less than $300, the Behringer DEQ2496 and an 8800 mike works fine. A youtube vid shows how to use it. I have mine eq'ing the bass on my setup....no more moving the speakers to find the perfect spot. Put them where you want them and eq it to perfection.


DEQ2496 Room Correction EQ Guide - YouTube
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Old 27th February 2014, 02:13 AM   #902
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Originally Posted by DeltaStar View Post
There's one thing I'd like to do, I like flat eq'd sound, but can't figure out a way to do with that distance, to long for rca cables, maybe a comp and software? any advice here welcomed . Like to see how far they are off in freq response. Thanks
And here's a thread that you might find educative and handy: Room Correction with PEQ
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Old 27th February 2014, 03:41 AM   #903
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I have 2 DBX Driveracks that have the autoeq wizard, I can't use them because the HF on the Acoustats isn't enough output for room correction to work. Bad roll off's and to much to boost flat, I could set the Driverack from 20hz to14khz and sacrifice the rest.
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Old 1st March 2014, 05:38 PM   #904
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I think room correction is useful but shouldn't always be used.
I'll explain:
When I first got my 2+2, I used an old pio receiver with MCAAC room correction as a preamp, with a Hafler xl280.
Yes, this the old rc system did a good job of fixing things up, though i know my Denon 4311 (with the lastest and greatest Audessy scheme) could've done better.
How does this rc work? I think that it takes the analog signal, digitizes it, equalizes in the digital domain, then reconverts back into analog. Obviously, that is not good.
But, I discovered that room correction WAS useful. I had a tv hooked up to my receiver, and wrote down the results. I found that slight changes in speaker positioning could result in changes that affected calibration.
What i am saying is that room correction can be very helpful in setting the speakers up!
My research on the net indicated that deviations less than 3db are probably not noticeable, so that was my goal.. RC jacked up 50hz output by 5db and 6 db, by moving them further away from the wall and putting rug runners (Walmart- $10 each) behind them, mcaac jacked output up by 2db and 3db.
If your speakers are not angled right, you'll see jacked up high frequencies and (I think) drops in mids.
I think any old receiver with room correction can be used for this purpose, give it a shot. Shoot for results where the deviation is no more than 3db in any band. If you achieve it, put the rc unit away, enjoy the sound.
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Old 10th March 2014, 03:45 PM   #905
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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.
Thank you for the info.

I pulled the sock down on one of the panels last night and it doesn't appear to be very dusty or dirty, but I'll go ahead and vacuum it before I heat up the mylar. When heating, is there an approximate target temperature I should be trying to get the mylar up to to successfully accomplish the technique? I have a hand held infra-red pyrometer I can use to monitor the temperature.

And I do have a distributed bass system (four subs) to cover the low end, so my Spectas are getting plenty of reinforcement in the first octave.

Thanks,
Michael
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Old 10th March 2014, 03:55 PM   #906
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Default High frequency adjustment

Is there a recommended setting for the high
Frequency knob on my 2+2's?
What position did they ship with ?
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Old 11th March 2014, 07:12 PM   #907
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Quote:
Originally Posted by katana1100 View Post
Is there a recommended setting for the high
Frequency knob on my 2+2's?
What position did they ship with ?
The speaker has a variable high-frequency control to allow the user to adjust the amount of extreme high frequency content. Therefore, there is no 'correct' setting, and the control should be set where the sound is most pleasing to your ears (and generally with the same setting on both speakers).

Acoustat did preset this control before shipping, but this should not be construed as the 'correct' setting, but rather an attempt to provide the user with a 'typical' setting. Since Acoustat produced many versions of the MK-121 interface as used on the Model 2+2, giving you an exact answer as to that 'typical' setting will be difficult, without knowing more about the specific version you have.

So, your best bet is to adjust by ear and enjoy!
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Old 11th March 2014, 07:18 PM   #908
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Originally Posted by tinnitusintx View Post
Thank you for the info.

I pulled the sock down on one of the panels last night and it doesn't appear to be very dusty or dirty, but I'll go ahead and vacuum it before I heat up the mylar. When heating, is there an approximate target temperature I should be trying to get the mylar up to to successfully accomplish the technique? I have a hand held infra-red pyrometer I can use to monitor the temperature.

And I do have a distributed bass system (four subs) to cover the low end, so my Spectas are getting plenty of reinforcement in the first octave.

Thanks,
Michael
I wish I could give you a target temperature for the mylar shrinking, but when Acoustat used an industrial heat gun to shrink the mylar, it was done by 'gut feel and experience' rather than any specific temperature. Since your mylar is already pre-shrunk, you need apply only a small amount of heat to get back to optimal tension. The goal is to keep the heat source several inches away from the louvers, and constantly moving so that the heat does not build up in a small area. I suggest you start out with a very light heat application, and if that does not yield the desired reults, the process can be repeated as necessary.
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Old 11th March 2014, 07:45 PM   #909
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Quote:
Originally Posted by AcoustatAnswerMan View Post
I wish I could give you a target temperature for the mylar shrinking, but when Acoustat used an industrial heat gun to shrink the mylar, it was done by 'gut feel and experience' rather than any specific temperature.
Target temp for heat shrinking Mylar is 150 C - 170 C
Capaciti mentioned that he set his heat gun to 250 C and used a thermal probe to determine that keeping the heat gun 5cm above the surface of the mylar provided 150 C at the Mylar surface. I'm sure this distance would vary depending on specfic heat gun nozzle shape and blower speed, but would give you a starting point to experiment.
Mechanical Sectioning .vs. Silicon dots for resonance control

As AcoustatAnswerMan mentioned, heating shrink Mylar with a heat gun is a bit of an art.
It may be worth your time/money to obtain some surplus mylar to practice with before working on your Acoustat panel to avoid accidently melting a hole in the diaphragm.

The key think is to keep the heat gun moving steadily across the surface, never pause with the heat gun over the diaphragm.
Complete a series of passes at a given distance and heat setting. If the diaphragm tightened up as you desired, your done. If not, try a slightly higher temperature setting or closer distance until you notice the tension increasing.

Last edited by bolserst; 11th March 2014 at 07:48 PM.
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Old 11th March 2014, 07:52 PM   #910
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Quote:
Originally Posted by AcoustatAnswerMan View Post
I wish I could give you a target temperature for the mylar shrinking, but when Acoustat used an industrial heat gun to shrink the mylar, it was done by 'gut feel and experience' rather than any specific temperature. Since your mylar is already pre-shrunk, you need apply only a small amount of heat to get back to optimal tension. The goal is to keep the heat source several inches away from the louvers, and constantly moving so that the heat does not build up in a small area. I suggest you start out with a very light heat application, and if that does not yield the desired reults, the process can be repeated as necessary.
Thanks for info. I went ahead with the heating technique last night using a blow dryer held about 6-8 inches away and moved it in a pattern the way one might paint a panel. I used my infra-red thermometer and restricted membrane temperature to 135 F and exposed it to that level of heat for about five minutes. I do believe it helped as I hear no more panel slap (though I haven't tried to take them up beyond an SPL of 90db), but at higher volume settings (85-90 db) I am hearing some mid and lower mid range distortion....aggravated mostly from low pitched toms and floor toms and heavy, low notes on a distorted guitar. This distortion doesn't show up immediately...for instance, I started an album and all sounded great until about the fourth or fifth song at which point the distortion gradually started to show up (starting out sounding like a little static) and got progressively worse from there. A slight decrease in the volume would all but eliminate it. Also, it seems as if one panel has slightly lower output than the other....most noticeable with hi-frequencies. I've never checked the bias on the transformers and now that I've discovered how to do that will have a look at that tonight.

- Michael

Last edited by tinnitusintx; 11th March 2014 at 07:58 PM.
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