Thanks for your quick reply. I will contact them and see what they have to say...
I thought about just leaving the felt off the high frequency panels but then realized that unlike the mids and lows, there are no panels receiving only the highs, just full range...curious why Acoustat didn't have a panel dedicated just to highs or mid/highs..????
I thought about just leaving the felt off the high frequency panels but then realized that unlike the mids and lows, there are no panels receiving only the highs, just full range...curious why Acoustat didn't have a panel dedicated just to highs or mid/highs..????
Acoustat did not make a dedicated highs or mids panel simply because it wasn't necessary. The nature of Acoustat's panels, and their associated driving system, make the panel full-range capable. So why bother with extra crossovers elements, and the issue of acoustically blending different radiators? Unlike some ESLs, Acoustat panels have always been full range capable. In the pre-Spectra models, all panel area is driven equally at full range. It was only with the introduction of the Spectra models that Acoustat began the practice of tailoring the frequencies sent to some panel areas, in an effort to electrically curve the panels, rather than a mechanical arc between panels. I recommend Jim Strickland's Spectra Whitepaper for further reading.
In regards to the felt dampening pads, some people seem to prefer the sound without them. I've also heard of some people replacing the felt pads with adhesive tape. I'm not a fan of either idea, but you do have options. Their purpose is to dampen resonances in the panel, but I would not describe the felt pads as absolutely necessary. But being a "factory guy", with great faith in the original design, I say they should be there and unmodified. Your mileage may vary.
In regards to the felt dampening pads, some people seem to prefer the sound without them. I've also heard of some people replacing the felt pads with adhesive tape. I'm not a fan of either idea, but you do have options. Their purpose is to dampen resonances in the panel, but I would not describe the felt pads as absolutely necessary. But being a "factory guy", with great faith in the original design, I say they should be there and unmodified. Your mileage may vary.
Thanks for the reply.
I was just wondering why the 6600's have dedicated bass panels, dedicated mid/low panels, but not a dedicated mid/high. I know they can run full range but with the resonance issue in the lows, why not run a panel high/mid instead of full range to get the highs?
I was just wondering why the 6600's have dedicated bass panels, dedicated mid/low panels, but not a dedicated mid/high. I know they can run full range but with the resonance issue in the lows, why not run a panel high/mid instead of full range to get the highs?
The segments of the panels are "dedicated" only in the sense that they are driven by frequency-limited signals. Otherwise all panels are the same and capable of full range operation. All panel area is driven at low frequencies because it is necessary for excellent bass response (more area = better bass). Therefore, the felt pads should be present on all panels (in my opinion).
Hello,
I own what l was told was a model 3.
On the back above the interface there is what looks like a hatch that is screwed shut. I am wondering if someone can give me a definitive answer if these speakers came from the factory as is or were they modded at one time.
Thankyou for your time,
Tim
I own what l was told was a model 3.
On the back above the interface there is what looks like a hatch that is screwed shut. I am wondering if someone can give me a definitive answer if these speakers came from the factory as is or were they modded at one time.
Thankyou for your time,
Tim
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The model 3 did not look like that - but as long as the panels are two 9' panels flanking a single 8' panel, and the interface is stock, it should sound same. That "hatch" appears to be a part of the panel to base support.
Looking closer, the speaker posts are not original, and appears to have some work done inside...maybe interface has been modified?
Looking closer, the speaker posts are not original, and appears to have some work done inside...maybe interface has been modified?
What you have is a Model 3M. The hatch on the rear is factory original and was provided for attachment of an optional woofer module, in which case it would be called a Model 3MH, for Modular Hybrid. These speakers used the limited frequency range interface MK131. You have the full-range interface MK121, thereby making it operationally the same as a Model 3. The M/MH series was a "great idea" that didn't last very long, compared to the long-lived Model 3.
Your interfaces were modified by Sounds Like New. You can likely trust the work that was done by them. This pair is in pristine shape - thanks for sharing an unusual model.
Your interfaces were modified by Sounds Like New. You can likely trust the work that was done by them. This pair is in pristine shape - thanks for sharing an unusual model.
I have an Acoustat Trans Nova Twin 200 that's emitting a constant hum out of just one channel. Sometimes it's a bit louder just as it's switched on then settles in to a constant hum. It disappears into the music at volume but is quite distracting between tracks. First steps?
z-man99 - this thread is more about Acoustat's loudspeakers. You might get better traction posting your inquiry in the Solid State Amplifier section. Helpful info would include 1) if this is a new problem (i.e., it worked okay before), and 2) how this amplifier is connected with associated equipment. Reminder that this amplifier has floating outputs, and therefore the black output terminals of each channel must NOT be connected together by any means (like a speaker switching box would likely do).
Hi. I have a pair of Model 3MH speakers . The back plate says Mk131 interface but I believe they are 141 due to the 100k resistor present.see photo of (new next to the old).
One of these resistors fried and it melted the panel wires. I resoldered the wires and kept the back open during a test play. The resistor was glowing orange and shooting sparks when turned to high volume levels. At lower volume the speakers still sound good. I’m wondering what else might have been damaged. I have had trouble finding an exact replacement for these 100k 50watt resistors. I found these in the photo at Digikey but they are only rated at 2440v. Do they have to be minimum 5kv rated? If so does anyone know where I can find a pair? I have seen some rated that high but they are too big to fit on the board. Should I replace all the caps and diodes while I’m in there? Thanks for any suggestions.
One of these resistors fried and it melted the panel wires. I resoldered the wires and kept the back open during a test play. The resistor was glowing orange and shooting sparks when turned to high volume levels. At lower volume the speakers still sound good. I’m wondering what else might have been damaged. I have had trouble finding an exact replacement for these 100k 50watt resistors. I found these in the photo at Digikey but they are only rated at 2440v. Do they have to be minimum 5kv rated? If so does anyone know where I can find a pair? I have seen some rated that high but they are too big to fit on the board. Should I replace all the caps and diodes while I’m in there? Thanks for any suggestions.
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I think the resistor you found will be okay as long as its physical length is about the same. The part does not need to be rated at 5 kV. Acoustat used a variety of vendors for this part, and voltage rating was never a key parameter. I do find it odd that the resistor was "glowing orange and shooting sparks". This could indicate a problem elsewhere, or not. Failures of that resistor are unusual, so I don't have much experience to rely on in this case. I would suggest you replace the resistor, and make sure no wires are touching it after final assembly. Then proceed carefully to see if you fixed the problem. If not, write back and we'll go from there.
Thanks for your answer. I’m changing the resistors now. Will see what happens. High humidity where I am in San Diego near the ocean. Perhaps 40 years of moisture contributed to the problem? The resistors had some surface corrosion. Hope the other parts inside are ok. Thanks again.
Getting near the finish line on the new frames for the Spectra 6600's I picked up last Spring. Wow, way more work than I anticipated...I made numerous changes from the original, including:
If I had to do it again, I would probably contract it out to a cabinet shop! About 10 times the work I was expecting!
Here are a few picts taken while under construction...
- I used recycled redwood for the frames instead of mdf with all mortice and tenon joints, reinforced with glue and lag screws.
- I placed the vertical and horizontal members behind the panels.
- I routed a channel in the front vertical members and ran the bias wires inside the channel, held in place with rubber screen spline.
- I ran the stator wires down the back outside frame members inside quarter round chases that hide all the wires and gave the rear of the frame a nice rounded profile.
- I made a sandwich of 1/2" felt, polycarbonate, 1/8" steel plate, and 1/2" oak for the lower board that that interface bolts to. I bolted this to the frame members using threaded inserts.
- I used barrel nuts to mount the panels instead of tee nuts.
- I mounted the interface on a steel plate and then bolted that through 3/4" red oak into tee nuts welded to a 1/8" steel base plate.
- I reversed one panel on the top row and one panel on the bottom row so that I could have the bias wires exit all the panels on the side facing the interior of the speaker. This allowed be to route all of the bias wires down the inside vertical members.
- I cut grooves around the outside of the frame and will have separate front and back cloth covering, held on with screen spline in the grooves. This will allow for removal of the coverings independent from each other without all the staples.
- I put countersunk magnets on the outside edge of the frame to hold trim boards that will cover the sides and the screen spines holding on the grill cloths.
If I had to do it again, I would probably contract it out to a cabinet shop! About 10 times the work I was expecting!
Here are a few picts taken while under construction...
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I talked to the source you suggested but they had no records going back to when Acoustat was in business. They also said they didn't have anything with rabbit hair...
I had several spare panels I bought and will use the felt from a few of those as needed.
Thanks for your kind words and help!
Felt comes in different densities, and I am not sure which is best for Acoustats, but here is a possibility.
This F-13 is one of the grades used for "...sound absorption and vibration deadening":
1/4" x 12" x 24" Felt from Amazon
From what I read, F-10 would be even better, at sound absorption. If you can find it in small quantities.
This F-13 is one of the grades used for "...sound absorption and vibration deadening":
1/4" x 12" x 24" Felt from Amazon
From what I read, F-10 would be even better, at sound absorption. If you can find it in small quantities.
Hello! New to this forum. I joined especially to gather info on my Spectra 1100's. I bought these new about 28 years ago and they were my only speaker for nearly all of that time. I'm using a Mac 2100 to drive them. I'm now retired and over the past 3-4 years have gathered a small collection of not only speakers but other components. I think it's time for some crossover rebuilds on the Acoustats. So....What am I looking at to upgrade the crossovers? I have a good tech in town but would like advice on brands to use, modifications that are worthwhile, etc. I am also open to sending these out to someone. Budget is under $500, maybe $600 at most, to have both done. Thanks in advance. Chuck