Yes, best sound in the Spectra 11 is achieved by having as few analog components as possible in the signal path. I only have a 1 ohm resistor (replaced with a new one) in the path with active XO and it sounds the best. Actually I could even remove the resistor as my amp would probably handle the low impedance just fine.
Yes that sand 1ohm res. in the 11-1100.. need to be upgreaded.....But I think it there for the tranfourmer....an the Amp....But we cant have one without the other...so I would not pull it less you don't push the speaker that hard....an run like a 10watt SE tube amp....hehe..An yes drop the bias feed res..from 500meg....to 30meg...an they well come a live!
Best bias Mod for any an all Acoustats ever...
As with the C-mod....there are the Caps an res.....But thay add so much to the speaker sound an now with the Mod I posted...60 tube watts can give me the output I have always needed......the mod were I move the one panel to have only ...most above 1khz.....I can pull most of the Backing off the one panel.....An WOW....what a sound stage.....best in 30 years....an a vary sweet tubey topend..
For me an my ears.... the biges prob with the Spectra 11-1100.....is the way the panels are monted.........the monting is done by running two Horizontal wood bars......to hold the panels.......
All other... Acoustat Stock Panel are only mounted Vertical......it is not the Hoizontal bars.....per-say......it that the wood bars run behind the panels......were the output is....now most well say thay don't hear a thing bad in this setup.....or it could be the feedback from the bass box.....the two ends of the panels....are un-bolted...an are hanging free ....but if push hard thay buzzs......................
Mount the panels on two Vertical bars... so the panels can be mounted bolted down....an with nothing behind the middle of panels....an get better sound..........................all just one-mans finding
Best bias Mod for any an all Acoustats ever...
As with the C-mod....there are the Caps an res.....But thay add so much to the speaker sound an now with the Mod I posted...60 tube watts can give me the output I have always needed......the mod were I move the one panel to have only ...most above 1khz.....I can pull most of the Backing off the one panel.....An WOW....what a sound stage.....best in 30 years....an a vary sweet tubey topend..
For me an my ears.... the biges prob with the Spectra 11-1100.....is the way the panels are monted.........the monting is done by running two Horizontal wood bars......to hold the panels.......
All other... Acoustat Stock Panel are only mounted Vertical......it is not the Hoizontal bars.....per-say......it that the wood bars run behind the panels......were the output is....now most well say thay don't hear a thing bad in this setup.....or it could be the feedback from the bass box.....the two ends of the panels....are un-bolted...an are hanging free ....but if push hard thay buzzs......................
Mount the panels on two Vertical bars... so the panels can be mounted bolted down....an with nothing behind the middle of panels....an get better sound..........................all just one-mans finding
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It is entirely permissible to replace the Spectra 11's 1-ohm resistor with a lower value...even down to zero ohms. In the Spectra 1100 (same panel and transformer), the function of the HF balance switch is to change this value from 1 ohm (low) to 0.4 ohms (medium) and 0-ohms (high). As long as your amplifier is capable of handling the reduced impedance at high frequencies, 0-ohms is okay and will yield the most extended top-end response.
The panels are mounted in the Spectra 11 and 1100 the way they are for very good reason. The original prototypes, with full length mounting, exhibited a significant midrange anomaly due to the extra cavity between the edge of the panel and the frame. Eliminating the full-length mounting, and going to short 'tabs' to mount the panel, got rid of this problem.
And just to be clear, the C-mod has no application to any of the Spectra models.
I know Tyu is a big advocate of reducing the value of the bias resistor, and each Acoustat owner is certainly free to modify and experiment to their heart's delight. However, it is this man's opinion (and in fact, fairly well-established fact) that significant reduction of the bias resistor's value will tend to reduce the speaker's optimum 'constant charge' mode of operation, which will increase distortion.
The panels are mounted in the Spectra 11 and 1100 the way they are for very good reason. The original prototypes, with full length mounting, exhibited a significant midrange anomaly due to the extra cavity between the edge of the panel and the frame. Eliminating the full-length mounting, and going to short 'tabs' to mount the panel, got rid of this problem.
And just to be clear, the C-mod has no application to any of the Spectra models.
I know Tyu is a big advocate of reducing the value of the bias resistor, and each Acoustat owner is certainly free to modify and experiment to their heart's delight. However, it is this man's opinion (and in fact, fairly well-established fact) that significant reduction of the bias resistor's value will tend to reduce the speaker's optimum 'constant charge' mode of operation, which will increase distortion.
Thanks for the info on the Spectra input res.......... thay were put in to pull the topend down?..............
An if these res. are pulled...with the right Amp...no harm will come to my Spectra 3 trans........?
what if it not the right .....?
As for my finding on geting better panel output..... buy droping the bias feeder res....less than $5......two 30meg 1watt.....can be paralled with the 500meg.....no removel of any stock parts.......don't like ....can be pulled ezzy.........the 500meg sounds like it pulling the top down.....the 30meg opens up the topend..
As for the increase distortion.....if this is how it sounds I be droping my feeder to 5meg......even with the increase distortion Andy speaks of...I have NO Doudt hes right............Acoustats still sound better than any other ESL I have ever owned.
An if these res. are pulled...with the right Amp...no harm will come to my Spectra 3 trans........?
what if it not the right .....?
As for my finding on geting better panel output..... buy droping the bias feeder res....less than $5......two 30meg 1watt.....can be paralled with the 500meg.....no removel of any stock parts.......don't like ....can be pulled ezzy.........the 500meg sounds like it pulling the top down.....the 30meg opens up the topend..
As for the increase distortion.....if this is how it sounds I be droping my feeder to 5meg......even with the increase distortion Andy speaks of...I have NO Doudt hes right............Acoustats still sound better than any other ESL I have ever owned.
I don't know if I have a very satisfying answer to your question. The arrangement of the Spectra sectors was felt to give the most effective dispersion while maintaining a precise sound stage. That is, creating an electrically curved speaker from a flat transducer array. Which by the way, is convex as viewed from either front or rear, which is not possible with a physically curved or arced array.
Did Acoustat ever try other arrangements? I don't recall that we did, but that was along time ago so I can't be sure. Jim Strickland was the genius behind the Spectra approach, and as we were all pretty happy with the result, there was little or no questioning of his techniques. My contribution to the Spectra development, other than mechanical and cosmetic design, was final tuning of transformer ratios and sector resistors values. In other words, the final frequency response.
This is not to say that other arrangements won't yield good results (but maybe not), although it would be quite a bit of work to rewire the segments in order to find out. I do know that swapping the left and right arrays on Spectra yield some very weird and unnatural results!
Keep in mind that the equalization provided by the transformer system is based on the relative area of the full range, mids & lows, and lows-only sectors. Therefore, any attempts to rearrange the sectors should keep the area of the respective segments the same. Otherwise, serious frequency response anomalies will result.
Hi Andy and everyone,
Long time Acoustat fan and owner of various models here. I appreciate all the advice and comments in the forum. I could use help with a project. I picked up a pair of Model 2's that I am repurposing as 1+1's. I am looking for HV wire to extend from the top panels to the interface. I am also moving the interface a few feet away from the panels so I'll need wire for that - about 50' total or 3 x 16' of the colored wire. Any advice whether I can use 5Kv or 10Kv? Thanks!
Long time Acoustat fan and owner of various models here. I appreciate all the advice and comments in the forum. I could use help with a project. I picked up a pair of Model 2's that I am repurposing as 1+1's. I am looking for HV wire to extend from the top panels to the interface. I am also moving the interface a few feet away from the panels so I'll need wire for that - about 50' total or 3 x 16' of the colored wire. Any advice whether I can use 5Kv or 10Kv? Thanks!
I would recommend the use of 10-kV rated wire, as that is the rating of the original Acoustat custom-made wire. High-voltage wire is available from some of the better electronics distributors like Newark or Allied. What you find will likely be larger in diameter than the original wires, and in only one color, so you'll need to devise a color-coding method. I recommend running the front stator, rear stator and bias wires in three separately-sheathed bundles for maximum corona-prevention. The sheathing can be done with plain ol' PVC tubing.
This makes sense because the baffle frame width was much wider on this model to match the width of the woofer cabinet(compared with a 1+1). Diffraction from the wider baffle frame edges would result in a peak/dip pair in the midrange with the panel centered between the baffle edges. Rather than mounting the panel to crossbars or tabs, do you recall if offsetting the panel toward an edge was considered as a solution? This seems to be popular with magnetic planars.
I don't recall that that option was explored. Interesting idea, but I suspect one might still have a problem if the panel was mounted along its entire length. You'd probably still need to use the 'tab' mounting method.
I have some new to me Acoustat Model 3 speakers I have been running for three weeks now. At first I thought they were perfect, but I now know there is one problem. The speaker I'm running as the right channel has a "buzz" or vibration that happens with deep, loud bass, especially on transients. I think it sounds like it's coming from the plastic grid that holds the wires in place, and not the mylar panels. I switched lines in to the amp to confirm it was only happening on the right channel. With the bass line that caused the worse buzzing with the channels hooked up correctly, swapping them lead to no buzzing in the left channel. I believe I can hear the buzzing isolated to the top right of the speaker.
Don't get me wrong, I love these things, I just want to get them to as close to perfect as I can. I assume I'll need to roll the sock down and take a look inside. I already tried unplugging them for a few hours and lightly running a vacuum over the speaker with the sock still on, which years ago did fix a rattle in my 1+1s.
What should I look for when I roll the sock down? Also, are there any experts near SE CT who might be willing to come take a look at these? I have to admit I'm a little nervous about messing anything up.
Don't get me wrong, I love these things, I just want to get them to as close to perfect as I can. I assume I'll need to roll the sock down and take a look inside. I already tried unplugging them for a few hours and lightly running a vacuum over the speaker with the sock still on, which years ago did fix a rattle in my 1+1s.
What should I look for when I roll the sock down? Also, are there any experts near SE CT who might be willing to come take a look at these? I have to admit I'm a little nervous about messing anything up.
Out of the 10pr of Acoustats an 4pr Quad ESLs.minny.Magnepan.....I have had.....all can be driven to slap or buzz.....with low bass.......my M3 I have now well slap ....it the right side..... no matter what panel speaker I put there.... closest to a brick wall.....
40 years of this hobby......... still have not found the....perfect speakers...but the Acoustat get just about 95% right..........for me that's good as I have got...good luck
40 years of this hobby......... still have not found the....perfect speakers...but the Acoustat get just about 95% right..........for me that's good as I have got...good luck
This is not an entirely uncommon phenomenon. As correctly pointed out by TYU, all ESL's will exhibit this behavior at some point. However, since you are experiencing this only in a specific area of one speaker, you may have a problem that is likely correctable.
Most commonly, this is caused by a lack of tension in the diaphragm and/or a foreign substance caught in the gap between the stator and diaphragm. The methods for correcting these issues have been discussed previously in this and other DIYAudio threads, so I'm not going to repeat them here. These methods are pretty easy and generally effective.
Much less commonly, you may have a loose wire that is reducing the excursion space of the diaphragm in a small area. This is much harder to fix but not impossible with some patience and skill. Techniques for this have been discussed previously, as well.
Thanks to you and everyone else for your responses. I have perused the archives here and think I know the way forward, but I still have two questions.
First, do I need to discharge the panels before vacuuming? I know I will have to if I need to do any gluing, but if I pull the sock down and play something with bass, see what seems to be causing the buzz/rattle, if vacuuming looks to be the solution can I just vacuum, or should I discharge the panels?
Second, if gluing stator wires is required, does anyone have a link to good pictures of this operation?
Well, I've pulled all the staples and pulled the sock down. Looking carefully while playing the music that's been making the panel buzz, I don't see any obvious loose wires.
Is it possible for the louvres to become loose?
When retensioning with a hair dryer, do people leave the speakers upright? Or do you need to take the panels completely out?
I will start with some canned air and a thorough vacuuming, but I'm trying to prepare myself for the next step. Many thanks for all your help.
Is it possible for the louvres to become loose?
When retensioning with a hair dryer, do people leave the speakers upright? Or do you need to take the panels completely out?
I will start with some canned air and a thorough vacuuming, but I'm trying to prepare myself for the next step. Many thanks for all your help.
Absolutely you should discharge the panel before vacuuming or using compressed air. Otherwise the electrostatic force may tend to hold on to any bits of foreign material.
Don't expect to 'see' what's causing the problem. Most likely you won't see anything.
I've never heard of loose louvers, and even loose wires are not very common. I would expect only a severely damaged (and visually obvious) louver to cause any problems. Minor broken pieces, chips, and cracks are usually not for concern, unless of course a small piece has broken off and is trapped in the electrostatic gap.
The panels can be left in the frames for the re-shrinking process, and position is not critical. Do discharge the panels before re-shrinking.
I am not aware of any specific procedures or photos for re-gluing the wires (never done it myself). I suggest not worrying about that for now. Vacuuming and possibly re-tensioning the diaphragm is your best bet, and the most likely cure. Keep in mind that vacuuming and/or compressed air(which should be done first) and re-tensioning may need to be done several times before it is successful.
MrAcoustat has passed away
Hey, I just read at audiocircle that MrAcoustat passed away. The post was made mid July
MrAcoustat
Hey, I just read at audiocircle that MrAcoustat passed away. The post was made mid July
MrAcoustat