Check this out: So as you can see, the far speaker is toed out while the near one is toed in significantly more than the other is toed out. My point is this is where they have to be to project a perfectly coherent sound stage where they disappear and only the music remains. 1/8" deviation by either and the image disappears. Very strange. I stumbled on this positioning while incrementally toeing them further out. I was not paying attention to symmetry but rather that they faced my listening chair at the same trajectory which is a bit off to the left of center. I knew this. When I adjusted them to zero toe in/out since they were so close and moved my listening position to center, it ruined the image. Is it possible my listening position is coincidentally exactly where the room acoustics place the sweet spot relative to where the speakers are located? These are Acoustat Monitor 3 ESLs. Both are exactly the same geometrically with no defect. I suppose my question is..can the room dictate speaker positioning regardless of symmetry?
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I can understand channel balance being affected by other objects but I find it odd that they produce a correct sound stage when asymmetrically placed. Mind you they do both point exactly to my listening chair which as I mentioned is slightly to the left of center. It's just really strange that this is the only arrangement where they sound correct in this space. Hence my query. In any case a very pleasant surprise. A moment of discovery. Like hearing them for the first time. I thought perhaps someone may have a technical explanation.
They are certainly interesting speakers, Pete. When/how did you acquire them?
From 1977 I gather. Unlike other ESLs, their diaphragms are not made of Mylar.
Output transformerless (OTL) tube amps inside, is that a correct description?
From 1977 I gather. Unlike other ESLs, their diaphragms are not made of Mylar.
Output transformerless (OTL) tube amps inside, is that a correct description?
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I've had them for about 5 years. I also have a pair of 'Model' 3. The diaphragm is Mylar. They are the second gen Acoustat after the Acoustat X, their first offering, the King, by many opinions back then. The Monitor 3 had the first rendition of the Model 3 as it's counterpart, the Model 3 being the first to come with the interface rather than the exclusive Direct Drive OTL mono, being the OTL's death knell. They are functionally identical. You can swap the interfaces for the OTL's on the Model 3 and they become Monitor 3. Acoustat thought it wise to provide ability to use one's preferred amp, hence the introduction of the interface and the beginning of the end for the OTL which was quickly phased out. The King was dead. Big mistake. There is no comparison to a directly driven ESL and the usual interface.
Dipoles inherently have reduced output to their sides, so room interactions tend to be less important.
Additionally, large speakers playing full range are very directional at high frequencies. This also decreases room contribution. Roger Sanders intentionally keeps his electrostatic designs directional because of the potential for improved imaging. But, it also gives you the "head in a vise" problem where the sweet spot is extremely small.
Though your speakers employ a faceted approach to widen the sweet spot, practically they are still very directional with a complex lobing pattern. That makes minor changes in speaker toe-in produce larger results than those seen in a less directional design.
A few thoughts on what may be going on in your particular setup:
1) By trial and error you found the precise spot where you're on axis with the central panel
2) You found a lobe between panels where the frequency response on that axis matches that of the reflected sound in your room. A laser aiming tool is helpful if you're looking for precise toe-in or out. If you want to be precisely on axis, looking at your reflection in the diaphragm works on most electrostatic speakers (flashlight over your head can help), though the Acoustat coating may be too matte to use that method (don't remember if their coating is on the front or back). You can also tape a mirror to the panel temporarily.
3) You have an asymmetrical setup in the room/rooms, so a symmetrical speaker arrangement doesn't work as well. The precise angles involved may be minimizing less desirable reflected sound that makes it back to your ears.
Additionally, large speakers playing full range are very directional at high frequencies. This also decreases room contribution. Roger Sanders intentionally keeps his electrostatic designs directional because of the potential for improved imaging. But, it also gives you the "head in a vise" problem where the sweet spot is extremely small.
Though your speakers employ a faceted approach to widen the sweet spot, practically they are still very directional with a complex lobing pattern. That makes minor changes in speaker toe-in produce larger results than those seen in a less directional design.
A few thoughts on what may be going on in your particular setup:
1) By trial and error you found the precise spot where you're on axis with the central panel
2) You found a lobe between panels where the frequency response on that axis matches that of the reflected sound in your room. A laser aiming tool is helpful if you're looking for precise toe-in or out. If you want to be precisely on axis, looking at your reflection in the diaphragm works on most electrostatic speakers (flashlight over your head can help), though the Acoustat coating may be too matte to use that method (don't remember if their coating is on the front or back). You can also tape a mirror to the panel temporarily.
3) You have an asymmetrical setup in the room/rooms, so a symmetrical speaker arrangement doesn't work as well. The precise angles involved may be minimizing less desirable reflected sound that makes it back to your ears.
Thank you Galu and mattsat. Although there is great synergy with this set up, I don't think it explains the phenomenon.
mattsat, your points are well taken. The speakers are zero toed in relative to my listening position orienting the center panels straight forward. The inner ones are focused right at my ears. I use the frames on the near side of each to visually line them up. If I move my listening position and follow with speaker alignment, the effect disappears. Tolerance is within 1/8", just a nudge will throw it off. It's like you know they are 'there' when they meld together as one which is what happens. I have been adjusting them using a laser and distancing them from front/back wall for years never being really satisfied they are correct. Something has always been lacking I knew was a matter of adjustment. I've made absolutely sure they are vertically aligned which was a revelation in itself. I settled down to compromise due to my off center listening position. Until now. So the discovery here is: for best performance they need zero toe in with listening distance such that inner panels be focused at my ears at the distance they are apart from each other, in this case 8', making my position 11' away. But the perplexing factor is, all needs to be shifted to the left about 4". That's why in the first pic the far speaker is toed out a bit less than the near one. Weird
mattsat, your points are well taken. The speakers are zero toed in relative to my listening position orienting the center panels straight forward. The inner ones are focused right at my ears. I use the frames on the near side of each to visually line them up. If I move my listening position and follow with speaker alignment, the effect disappears. Tolerance is within 1/8", just a nudge will throw it off. It's like you know they are 'there' when they meld together as one which is what happens. I have been adjusting them using a laser and distancing them from front/back wall for years never being really satisfied they are correct. Something has always been lacking I knew was a matter of adjustment. I've made absolutely sure they are vertically aligned which was a revelation in itself. I settled down to compromise due to my off center listening position. Until now. So the discovery here is: for best performance they need zero toe in with listening distance such that inner panels be focused at my ears at the distance they are apart from each other, in this case 8', making my position 11' away. But the perplexing factor is, all needs to be shifted to the left about 4". That's why in the first pic the far speaker is toed out a bit less than the near one. Weird
I forgot to mention that being 'sonically' perfectly aligned, there's virtually no "head in a vice" condition. The sweet spot is much bigger as they seem to meld together as one large speaker. Very similar to dynamic drivers when set up correctly. Have I stumbled across something no one else is aware of? Ime, I've always considered dynamic drivers to be far more critical in placement than the status quo and when finding the sweet spot with them, it's been more difficult to pinpoint within the ballpark it appears, because of the wider tolerance commensurate with the nature of their design. Although there's no "head in a vice" situation with them, I've always felt the actual sweet spot is much narrower than consensus dictates. In fact, I think the better the gear, the smaller the 'actual' sweet spot. IOW, capitalizing on the attributes of progressively better components by nature requires progressively greater attention to set up.
Disco.....thanks for posting your finding....
The Xs an the Monitor 3,4s with the panels front mounted to the wood....were moved away from in all the other Acoustat....the panels were mounted with the wood in back if they could be....to get better top end an more output.....So your right you have stumbled across something no one else is aware of? .....
Not if they dont have a pr of Acoustats
with there panels front mounted to wood frames....an then your room....looks like every thing i been told for 50 years not to do to get the best sound.
Looks like it works for you....have fun
By the way i well be moving my panels to the back of the wood...on a pr of model 3s.....for old time sake...why, hell
i done every thing but that....been over 30 years from having my Xs
The Xs an the Monitor 3,4s with the panels front mounted to the wood....were moved away from in all the other Acoustat....the panels were mounted with the wood in back if they could be....to get better top end an more output.....So your right you have stumbled across something no one else is aware of? .....
Not if they dont have a pr of Acoustats
with there panels front mounted to wood frames....an then your room....looks like every thing i been told for 50 years not to do to get the best sound.
Looks like it works for you....have fun
By the way i well be moving my panels to the back of the wood...on a pr of model 3s.....for old time sake...why, hell
i done every thing but that....been over 30 years from having my Xs
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Disco......you dont think theres a big sound an trajectory diff in the way these panels are mounted?
there's virtually no "head in a vice" condition....only time i heard of the head in vice efeck was with 1,1+1 with there flat panels setup....
there's virtually no "head in a vice" condition....only time i heard of the head in vice efeck was with 1,1+1 with there flat panels setup....
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