How Much Torque?
OK, I got a couple of new panels for my 2+2s and need to correctly install a replacement for the one that's apparently kaput. Not sure what went wrong with the old one but the connections have been checked and the thing intermittently emits severely distorted sound. I noticed there were a couple of places where the panel's plastic frame had buckled, presumably because somebody over-tightened the bolts that hold it in the wood frame.
So now those bolts are torqued to 1 ft-lb with my electric screwdriver, which is about where the matching bolts were on the other side. Before I close it up, I'd like some advice on how much torque to apply so I keep the thing from rattling in its frame without risk of breaking the plastic. The replacement panel is not new, so I assume the plastic may be brittle.
Any opinions?
OK, I got a couple of new panels for my 2+2s and need to correctly install a replacement for the one that's apparently kaput. Not sure what went wrong with the old one but the connections have been checked and the thing intermittently emits severely distorted sound. I noticed there were a couple of places where the panel's plastic frame had buckled, presumably because somebody over-tightened the bolts that hold it in the wood frame.
So now those bolts are torqued to 1 ft-lb with my electric screwdriver, which is about where the matching bolts were on the other side. Before I close it up, I'd like some advice on how much torque to apply so I keep the thing from rattling in its frame without risk of breaking the plastic. The replacement panel is not new, so I assume the plastic may be brittle.
Any opinions?
As for tightened bolts, I have found hand tight is quite sufficient. In fact, I had once overtightened a panel, leading to increased rattle, which in turn caused me to buy a replacement panel. It was during the swap that I came to realize that "too tight" was an issue.
What does concern me in your situation is what exactly you mean by "buckled". Id imagine a scenario does exist that if the louver is cracked on both sides in a similar location the ability of the mylar to remain taut could be compromised and thus rattle.I certainly have a few minor chips in the louvers, but in no instance are there fissures through the frames entirity.
Have you tried or know of the hair dryer or heat gun treatment? Loosened mylar from constant common-use excursion does cause a rattling to creep in during heavy bass passages and the fix-all has always been a heat treatment. I do this biannually.
Another possibility is a lifted "spacer bridge" (my term). On the tops and bottoms of the pannels there is a t-shaped run of plastic that extends the width of the panel. Seems its a cap and spacer all-in-one. On 2 occasions the glue has ceased working and bridge/cap has lifted causing a pronounced rattling in that locale. In these instances i reglued and used halved wooden clothespins as wedges force the plastic back down and into place.
Rattling can also be due to loosened stator wires. Here i once again reglued by placing a dab of glue in that particular louver "square" and used a splintered popsicle stick to push the glue between stator and louver for reattachment.
Hope this helps
What does concern me in your situation is what exactly you mean by "buckled". Id imagine a scenario does exist that if the louver is cracked on both sides in a similar location the ability of the mylar to remain taut could be compromised and thus rattle.I certainly have a few minor chips in the louvers, but in no instance are there fissures through the frames entirity.
Have you tried or know of the hair dryer or heat gun treatment? Loosened mylar from constant common-use excursion does cause a rattling to creep in during heavy bass passages and the fix-all has always been a heat treatment. I do this biannually.
Another possibility is a lifted "spacer bridge" (my term). On the tops and bottoms of the pannels there is a t-shaped run of plastic that extends the width of the panel. Seems its a cap and spacer all-in-one. On 2 occasions the glue has ceased working and bridge/cap has lifted causing a pronounced rattling in that locale. In these instances i reglued and used halved wooden clothespins as wedges force the plastic back down and into place.
Rattling can also be due to loosened stator wires. Here i once again reglued by placing a dab of glue in that particular louver "square" and used a splintered popsicle stick to push the glue between stator and louver for reattachment.
Hope this helps
Fragile Framing
Here are some pictures to clarify what I mean by buckled. 01 and 02 show different instances where pressure from the plastic collar on the screw has collapsed part of the frame. In 03, the view is of the side of the frame that's against the wood, so I don't think it's significant as a source of noise; note the wrinkled appearance of the softer plastic inside the frame, however. I don't see anything like that on the others. Possible source of distortion? Fixable?
Here are some pictures to clarify what I mean by buckled. 01 and 02 show different instances where pressure from the plastic collar on the screw has collapsed part of the frame. In 03, the view is of the side of the frame that's against the wood, so I don't think it's significant as a source of noise; note the wrinkled appearance of the softer plastic inside the frame, however. I don't see anything like that on the others. Possible source of distortion? Fixable?
Attachments
You can confirm source of the rattle by using a paper towel roll to localize what you're hearing durring a heavy bass passage. Minus a screw in that position one should expect rattle due to friction between wood frame and louver. Then again, you could have the missing screw scenario while at the same time be experiencing rattle due to loose stator. These things are quite deceptive and tedious to track down. You should be able to reinsert bolt w plastic collar and use paper towel roll to locate position. I determine general area of rattle and then proceed to use a splintered popsicle stick to check for loose stators in that area by gently flicking the stator to see if it moves at all. A single loose stator can create an unfathomable amount of rattle. I'd also confirm that all bolts are just hand-tight and not torqued before proceeding with stator wire check technique.
Success!
I hope that will be the last time I ever have to strip one of those things down and replace one of the transducer panels, but the results have been beyond expectations! The sound is better than I can recall. It must have been damaged in our last move, which was 13 years ago. Anyway, thanks for all the encouragement.
I hope that will be the last time I ever have to strip one of those things down and replace one of the transducer panels, but the results have been beyond expectations! The sound is better than I can recall. It must have been damaged in our last move, which was 13 years ago. Anyway, thanks for all the encouragement.
Resonance issues?
Stereophile measured the Spectra 11 and 1100 waterfall plots. Theres resonance in the midrange around 2-3kHz. I cant see what's causing that. Is it the Spectra model frames or the actual panels or ....?
During development of the Spectra 11, we did find a distinct midrange peak. This was traced to the cavity on either side of the panel within the frame (necessitated by the frame being wider than the panel). The peak was considerably reduced by “opening up” the cavity by using smaller flanges to attach the panel to the frame, rather than full-length flanges as used on early prototypes. No doubt the plots fromStereophile still show some traces of that peak. Since the panel & frame structure for theSpectra 1100 is very similar, I would expect it to exhibit similar behavior.
So, to answer your question, I believe this behavior to be unique to the Spectra 11 and 1100 and is caused by how the panel is mounted in the frame. It’s not a characteristic of the panel itself (which is used in all Spectra models), nor a characteristic of the interface system.
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Thanks for clarifying the resonance source in those Spectra models. The wavelengths didn't fit with the Acoustat membrane or panel frame dimensions so I couldn't figure it out. Its good to know it only affected two models and seems like it could be easily fixed.
Here's a trivia question...
My copy of the Acoustat 2+2 user manual, which I got in 1982, is a photocopy. That's what the dealer gave me. On the top of page ll, obviously added after publication, is a fax number for 'Lee Nichols Arch'. Yesterday I downloaded a scanned copy from hifi-manuals.com, and darned if it doesn't have the same thing in the same spot!
Any idea who this guy is or how his name got to be on two copies obtained 37 years apart?
My copy of the Acoustat 2+2 user manual, which I got in 1982, is a photocopy. That's what the dealer gave me. On the top of page ll, obviously added after publication, is a fax number for 'Lee Nichols Arch'. Yesterday I downloaded a scanned copy from hifi-manuals.com, and darned if it doesn't have the same thing in the same spot!
Any idea who this guy is or how his name got to be on two copies obtained 37 years apart?
These just sold for $2600. Wish I had the money and a way to go get them. I would have bid more. Very happy for the new owner
...wish it was me. I think the Acoustat Spectra 11,1100..maybe have the best sound of them all!
I think it has all to do with 11,1100...No restors or caps being in the secdary side of transfourmer feeding the 3"side of the panels topend.... ...the restors are then added to the mids 3" side panels...….. Jim says it works the full 9"with MID...but there no lose in there top end...well it 19k,
NO other Acoustat Spectra dose this...all others stepup transfourmers secdary feed caps an big restors BEFORE they go to any part of the panels hight frcequency or mid or bass ....an then more restors are added,for mid an bass... this to my ears add to much bass.
0ne big Key with seting up 11,1100...Put only the bottem bolts in the panel frame.... an leve them lose..so you can lean the panels top forward ...leve the interface box lose....I put rubber beween the metal an the wood... leve the top bolts out....this must help big time with room standing wave...sound smooths out,get sweet, bass gets better....
My setup,big key ,No toe in.......12' apart...half way out in the room....
Over all best sound I ever got out of Acoustats….
Funny life, my first pr of 11s were in the 1990s...I heard this great same sound then......like full circles!
,
Have Fun with these Great speakers....Always
I think it has all to do with 11,1100...No restors or caps being in the secdary side of transfourmer feeding the 3"side of the panels topend.... ...the restors are then added to the mids 3" side panels...….. Jim says it works the full 9"with MID...but there no lose in there top end...well it 19k,
NO other Acoustat Spectra dose this...all others stepup transfourmers secdary feed caps an big restors BEFORE they go to any part of the panels hight frcequency or mid or bass ....an then more restors are added,for mid an bass... this to my ears add to much bass.
0ne big Key with seting up 11,1100...Put only the bottem bolts in the panel frame.... an leve them lose..so you can lean the panels top forward ...leve the interface box lose....I put rubber beween the metal an the wood... leve the top bolts out....this must help big time with room standing wave...sound smooths out,get sweet, bass gets better....
My setup,big key ,No toe in.......12' apart...half way out in the room....
Over all best sound I ever got out of Acoustats….
Funny life, my first pr of 11s were in the 1990s...I heard this great same sound then......like full circles!
,
Have Fun with these Great speakers....Always
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I respectfully disagree, sorry. I was an Acoustat dealer for many years.. I sold probably 10-12 pair of 11's and 5-6 pair of 1100's. Installed and setup most of them.
I have also personally owned a couple of different pair of 11's and a pair of 1100's.
Outside of the 2MH and 3MH, these were "my" least favorite Acoustat speakers. I have always thought there was too much disintegration between the panel and woofer. Very sluggish, slow and dark. But for the money, they were pretty decent.
Far from the best Acoustat's though...IMHO.
I forgot to add in my other post.
Never had a pr of 11 that the bias was not way off..….you got get the bias up to 5k,
Andy posted a fix for the new bias in these...years back
Or thay sound like this, i well use your words...
" there was too much disintegration between the panel and woofer. Very sluggish, slow and dark."
less see over 30 years.... I have owned,
Acoustat X with the tube servos
Model 2
Model 3-3pr have a pr
Model 4-2pr
1+1-4 pr, have a pr
2+2 have a pr
Model 6
spectra 11had 3pr.. have two pr now
Spectra 2 have a pr
Spectra 3 have a pr
All with there bias re-worket...these are all i have lived with last 30years...
Have fun with these great speakers...
All just one mans finding....good luck
Never had a pr of 11 that the bias was not way off..….you got get the bias up to 5k,
Andy posted a fix for the new bias in these...years back
Or thay sound like this, i well use your words...
" there was too much disintegration between the panel and woofer. Very sluggish, slow and dark."
less see over 30 years.... I have owned,
Acoustat X with the tube servos
Model 2
Model 3-3pr have a pr
Model 4-2pr
1+1-4 pr, have a pr
2+2 have a pr
Model 6
spectra 11had 3pr.. have two pr now
Spectra 2 have a pr
Spectra 3 have a pr
All with there bias re-worket...these are all i have lived with last 30years...
Have fun with these great speakers...
All just one mans finding....good luck
I'm not talking about anything needing "mods". I mean out of the box, new.
Most users are not going to open up a new pair of speakers and start modifying them. Of course, I'm talking about years ago, when these were still on the market.
I have owned all of the speakers you mention except for the Acoustat X. However, I can add the following: Model One's, 2MH's, 3MH's, Spectra 22, Spectra 33 and Spectra 44. So, yeah I have owned a bunch also.
I agree, just my opinion.
Most users are not going to open up a new pair of speakers and start modifying them. Of course, I'm talking about years ago, when these were still on the market.
I have owned all of the speakers you mention except for the Acoustat X. However, I can add the following: Model One's, 2MH's, 3MH's, Spectra 22, Spectra 33 and Spectra 44. So, yeah I have owned a bunch also.
I agree, just my opinion.