Are the DD amps designed after the Acoustat amps. How tall and wide are the ESLs. Single flat panel? Does he use them himself? |
Clio for $12,000 as listed on Roger’s web site does that include the amps? Why doesn’t he put a page up for the speakers and all the other neat stuff he makes like the 300 watt mono amps?
Atmasphere, those amps got damn hot. They were also easy to over drive if you did not cross to a sub. They hated doing bass. The best sound I got out of unmodded Acoustats was 2 + 2s driven by KMA 100s. They even did bass! I got rid of Acoustat’s interface and hooked up one huge 1:100 Sowter transformer which is crazy to drive but boy do they sound great. Yes, Soundlab owners love your amps. The question is should I do MA-2s or MA-3s:) |
Atmasphere, they were an undersung product but the company had trouble finding itself and was trying to be all things to all people. Initially all the Acoustats used a "direct drive" high voltage tube amplifier. The first Model was the "X" It was a beautiful 3 panel speaker with the amp mounted inside a plywood enclosure. Unfortunately it was very colored entirely due to the enclosure. They then moved to the Monitor series both three and four panel versions. It was the Monitor 4 which convinced me that they were on to something. It was with this speaker that I first played around with subwoofers. They then again redesigned the enclosures to make them easier to manufacture. These were called the 1, 2, the 3, the 4 then the 1+1, 2+2, 3+3 and 4+4. They felt their sales were low because people wanted to use their own amps so they came up with a two transformer interface which was relatively easy to drive. There were two versions of this interface. The problem with this was that us audio types preferred the Direct Drive amp. The smaller speakers unaided by a subwoofer were not impressive. But the 2+2 was almost an entirely different animal. Given an amp like the Krell KMA 100 they not only had the magic ESL midrange but killer dynamics. Put them with a subwoofer and all hell broke loose. As big as they are they remain very selfish speakers. Very few 3+3s and 4+4s were made. They were just two big and you had to run two interfaces and two amps with each speaker. The 4+4s were the size of the Soundlabs Majestic 845. The most important item that Acoustat brought to the world was the first totally indestructible electrostatic panel. Quads had given ESLs a bad name because they were very fragile and I think Acoustat suffered because of that. My panels are now 40 years old. The 1/2 life of the plastic used in their construction is 50,000 years. Unless you drive a stake through them they will go on forever. If you have heard any of the larger SoundLabs then you have essentially heard the 2+2 but with a bit more dispersion. Most of these speakers have been cannibalized and the panels beaten up. 2+2s in serviceable condition are hard to find. The Company was eventually sold to David Hafler who went belly up some time later.
Panel speakers have gained more acceptance and I think there is room for a lower cost full range ESL like the 2+2. The individual panels might cost $50 to make if that. The frame maybe $100. The transformer/power supply another $100. $400 all told for a speaker you could sell all day long for $4000.............
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Clio, Roger is absolutely right. ESLs should not be allowed to go under 100 Hz. To destroy that beautiful mid range with stuff any old crude sub woofer can do is a travesty. |
Tim, If you have been following those of us with panel loudspeakers who have a lot of experience with sub woofers, there is a strong belief that removing the very low bass from this type of speaker decreases distortion and increases power handling. With your speakers that have two crossover points at 500 and 950 Hz the effect will not be as pronounced. Clio and I have no cross overs so the effect is over the entire frequency spectrum. You did not roll off the Maggies at 100 hz so now you have the Maggies and 4 sub woofers competing with each other all out of phase. It should be no surprise that it sounded like garbage. But it is a learning experience and you know for sure that approach will not work:) |
Rix, it is impossible to isolate a driver putting out low bass. The pressure wave itself is what makes the whole house vibrate, not the woofers connection to the house.
clio you want to handle Tim. I'm tired of talking to myself.
millercarbon you just gave some of the worlds finest speaker designers the middle finger. I think you should read acoustics for dummies before you start spouting off about what is or is not possible. |
Tim, actually clio has a 12 foot wide sub woofer which goes deeper than just a single sub. Remember drivers closer together than 1/2 the wavelength of the highest frequency you want to reproduce act acoustically as one driver. Larger subs will allow you to go deeper as long as the enclosures are appropriately designed. I am not sure were this speed thing came in. Bigger drivers with appropriately sized motors are not slower but as the size and mass of the cone increases they become more difficult to control and keep their motion pistonic. All this is outlined by the driver's parameters which we use to design enclosures. I do not like ported sub woofers. They are more efficient and it is easier to get them to go lower but I have not heard one that to my ear is as accurate as a good sealed driver. The problem with sealed drivers is that you have to force them to go down using equalization and a lot of power. But the drivers we have today can easily handle it and with an amp with DF over 500, using a slightly over sized enclosure (Q around 7) you can get some really amazing bass. I personally see no use for drivers over 12 inches. In either a DBA or linear array system with 4 units you will never run out of drive in anything smaller than 40 X 20 feet especially if you keep the drivers up against a wall or corner.
Clio, I did not know you had an M60. What a tricky guy!. Just remove the Acoustats and put the Quads right down in the same place, same angle. Do both DBA and Linear Array and let us know what you think. The quads are point source which means they will not project power (volume) as well as a linear array. As you move back from the listening position the woofers will become progressively louder than the Quads. Down the block you will just hear the woofers:) As long as things are in balance at the listening position you are in business. Even in a DBA arrangement if you can keep the woofers closer than 5 feet apart that would be a benefit. Other people with lower cross over points could get away with more distance.
The 2+2s are nothing more than stacked 2s without the base. The angle is the same. If you could find another set of 2s you could make 2+2s out of them. I toyed around with the idea of making 3+3s but eventually I will go with Soundlabs. I think what Roger is doing is is rolling off the high frequencies at the outer edge of the Stators to make the panels effectively narrower as the frequency goes up which would increase high frequency dispersion. Making 2s or 2+2s disperse is IMHO fruitless. Just stay in your listening position and enjoy. |
Clio I find your choice of a 4th order cross over at 100 Hz interesting. I can use any slope I want up to 10th order and can change cross overs on the fly. After eons of experimentation I settled on a 6th order low pass and a 4th order high pass all at 125 Hz. This is remarkably close. Is this coincidence or is this great ears hear alike? How did Roger modify the Acoustats for greater dispersion? Did he change the angles of the panels? How does Roger design his ESLs? Sanders uses a flat panel and crosses to a transmission line woofer at 175 Hz. I have not heard them myself. I talked to him via e-mail of doing a 7' 8" panel as a line source and crossing lower at 100 Hz but he was resistant to that idea. ML does the curved panel thing which highly limits their low frequency response to 250 Hz because of non linearities in the curved panel. Soundlabs uses facet panels in a curved array covering either 45 or 90 degrees. Acoustat used two, three or four panel angled arrays depending on the model. Sanders is the most selfish approach his argument being that there is only one listening position and everywhere else is background music. Plus as you increase dispersion you get into more trouble with room acoustics. He is right on both counts but it is nice to be able to provide a balanced frequency response throughout the room even if you can not provide an image especially when theater is concerned. I do not believe 45 degrees of dispersion causes significant problems with room acoustics. |
I forgot to mention that clio has also eliminated 4 of the 5 primary reflections that cause comb filtering in the bass.
Another way to look at this is that the bass linear array is just a more specific DBA system. It will always require 4 or more drivers unless you listen in a closet. |
Thank you clio. You said something that is very important (to me at least)
Bass is not just about hearing. It is about feeling. Part of the rush of a live performance is the visceral sensation you get from accurately projected lower frequencies. This is not easy to do in the home environment. Very few systems do this well but it is vital if you want to feel as if you are at a live performance. Even with string quartets the cellos go low enough to feel to to mention the transients caused by banging and thumping on this that and the other. The "visceral" range is (I'm guessing) from 150 Hz down.
Tim, Magnepans are great speakers. If you remove enough bass from them you can get them as close as 28" to the front wall. Just put some acoustic foam directly behind them. There is this thinking that you have to keep the cross over as low as you can to prevent the woofers from getting up into your mid range. It is easier to blend in with the satellites at higher frequencies and this is particularly true with dipoles which you have just like clio. He crosses over at 100 Hz, not sure about the slope.
Many cross low because they are trying to avoid a high pass filter on the satellites which is also mistaken. Removing the low end from the satellites cleans up the midrange and increases your power handling. You can put a simple 6 db/oct high pass filter on your Maggies simply by putting a cap across the input of your amps the value depending on your input impedance. The equations are on line.
The reason clio is now feeling his bass is because his subs are now functioning as one driver and the arrival time (phase) is the same across the entire room. His Acoustats are now part of that linear array in the crossover zone. He is now getting his bass as one unified whole not the random output of various drivers around the room. Placing speakers around the room will smooth out response variations but because the speakers are more than likely 1/2 wavelength of the highest frequency you want them to carry apart, they are acting as individual drivers and transients are being smeared. This may be another reason DBA people want to stick with lower x-over frequencies. You can put the subs farther apart and get away with it. A SWARM system can work under certain circumstances. Low x-over points in smaller rooms. Once you pull your cross over up and get into a larger room say 15 X 20 you get into trouble.
What you hear is important. But with bass what you feel is more important. |
Ok, DBA SWARM subs are absolutely the only way to go I wish I had the cojones to take my 200 lb subwoofers and their 2000 watt amplifiers and toss them up in the air to let them play wherever they land happily ever after. But I am an old man and to stupid and weak to lift these things never mind throwing them up in the air.
I'm sure you guys are on gluten free diets. You need to switch to now to Keto! |
Oh and Tim I have used subs in every configuration you care to think about and have been using 4 subwoofers for......25 years anyway.
I am glad you like your system and that it works for you. Unless you are extremely lucky your bass below 40 Hz is for certain a mess. Lord knows what it is doing up to the x-over. If you send me pictures of your room and system I would be happy to fix it for you. I am working with another forum member who has Acoustats and was unhappy with his DBA system. Of course he is use to a level of detail and imaging that you can't get out of dynamic drivers so the muddiness of a DBA system would be more offensive to him. I have not heard back from him yet but I think we have finished adjusting his system.
I don't have to use a tape measure myself. All I do is set up a microphone and tap the measure button which is displayed on my PC. If I am happy with it I tap the enable button and all the volume, delay and frequency adjustment are made in a few seconds. Then I overlay my own response curves and we are good to go. No guessing and I am not relying on anybodies hearing not even my own. There is no way I could get bass this good by playing around and depending on hearing. You can't either especially with sub woofers thrown all over the room. |
Avanti I agree with you almost entirely. You do have to with your rooms acoustics physically but particularly when it comes to bass there are limits as to what you can achieve. You can not achieve SOTA bass without digital bass management and subwoofer control. First you have much more control over x-over frequencies and slopes. In the digital realm there is no phase shift. Then you can adjust the frequency response of the sub woofers so that they are up 3 db at 20 Hz. Tolerably sized sub woofers start rolling off at around 60 Hz and are down 6 to 9 db at 20 Hz especially if they are not closely coupled to a wall or corner.
With enough power this can be corrected with startling results. Putting on a 20 Hz tone is a riot. It sounds and feels as if it is coming from the whole house and everything buzzes and rattles. Dishes, silver ware, picture frames, the toilet and my teeth. At 60 Hz I can definitively localize the sound and the symphony of rattles stops around 40 Hz.
Tim, the best speaker control (room control) measure each speaker independently and adjusts each speaker independently. The problem with sub woofer systems is that they ignore the satellites. |
millercarbon the radiologists when doing a barium GI study call it FOS.
Blaming me for not knowing what you are talking about will not change the reality of the issue. All of you reverse the wiring of one of your sub woofers and tell us what you hear. millercarbon you are way out of your league. In my estimation filling other people full of your mythology is not an ethical way of dealing with your compatriots.
Tim, never trust anyone who is trying to sell you something. Arrival times (phase) are even more critical in the bass. I wish I could demonstrate that to you directly but that is not possible. Again, wire your subs out of phase and tell us what happens. Regardless of what anyone says, a phase (time) coherent system is more accurate and realistic than one that is not, particularly in the bass. I have nothing to lose because I am not trying to sell you a darn thing. Beware of Greeks bearing gifts. Go to a local club and have a listen. If your Hi Fi does not approach that sound quality playing similar and well recorded music you have problems you might want to conquer if you even care. Music is not something you just hear. You also feel it which is critical to the experience. millercarbon obviously does not understand this and is destined to wallow in mediocrity unless he changes his approach to life. It is not easy to achieve this with analog equipment but it can be done and there in lay the challenge. millercarbon would rather make excuses than except that challenge. Will you do the same? I hope not. It is a wonderful thing to be able to get home at night, go to the concert and feel as if you are really there. If not it is something to strive for which I did for 45 years. |
Oh, and Tim. I am not saying that in certain situations a DBA system may not be the easiest way to reasonable bass performance. It may work reasonable well for many people. What I am saying is that in the end it will not produce the most accurate and realistic results but do to do so usually requires advanced digital speaker control that at this time costs at least $6K. If however you have a tape measure, some savvy and some luck, you might be able to get there without the computer. An important part of this hobby is being able to screw around with your system to see if you can get it to sound better and in doing so you learn. So, start screwing around! |
Tim, sorry I did not get back earlier. I can not believe people are so far off on the subject of time and phase. Time and phase are intimately related. wire two of your subs backwards and see what you get. That is 180 degrees out of phase. You get exactly the same effect when the distance between speakers is different. The wave length of a 100 Hz tone is about 10 feet. If you put one sub 5 feet closer to you than another you get exactly the same effect as if you wired one speaker backwards. Music is not one tone so you get every frequency altered by a different phase angle. Then you have a range of frequencies to deal with at the cross over which depending on slope may be as high as 250 Hz. It is also not only about what you hear but about what you feel. In phase you feel the thud of that bass drum strike. Out of phase and you feel nothing. You can easily demonstrate this to yourself by reversing wires. A system that is aligned in phase and time is a wonderful thing to hear and feel. It is much more realistic. If I blind folded you, drove you around and brought you into the room you would think you were in a jazz bar. I'm afraid millercarbon is spouting off with excuses to support his infatuation with SWARM systems, all of which are entirely unsupported assumptions which in reality are entirely wrong. Humans are marvelous creatures. When they don't know what is going on they make stuff up. They mythologize. Zeus, great explanation for lightening don't you think? |
Tim No, Right now I have modded out Acoustat 2+2s. Quads are not linear arrays. Full range linear arrays have to extend from the floor to the ceiling. I am on the brink of getting SoundLabs Majestics 845s as I have 8 foot ceilings. Between the speakers is a theater screen. The sub drivers are front firing. The inner two actually face each other with three feet between them. This gets the driver closely coupled to the front wall.
The outer subs are against the side walls facing forward. Their drivers are closely coupled to the side walls. The main speakers are angled towards the listening position. A line extending through the sides of the speakers will intersect the faces of both subs on its side.
Your Maggies are linear arrays down to about 150 Hz where they convert to point source. In order to get the full linear array effect you would have to cross to the subs no lower than 150 Hz. But then your subs would have to be closer together, about 3 feet. I wish Maggie would make a speaker with 8 foot woofers. It would make life much easier.
I hope your listening position is not right against the wall. If it is move it forward a couple of feet. Sound waves are very slow. You have two subs back there with you and you hear those fractionally before you hear the ones on the front wall. This will smear transients. You want to hear all your subs at exactly the same time. You also have dipoles so you want all your sub drivers in the null zone beside each speaker. If your TV is mounted on the wall up off the floor you can put two woofers between the Maggies facing each other right up against the wall under the TV. Now If you try crossing at 150 Hz the subs will have to be no farther apart than three feet. So you would array them across the front wall and up the side walls three feet apart.You do not want to put a sub behind the Maggie. It will cause weird interactions with the woofer panel which is why I locate them in the null zone. With your woofers 3 feet apart they will all act as one driver and you will hear all of them at the same time. If you move them further apart and cross lower, 100 Hz cross puts the subs 5 feet apart you will have a very important segment of the bass drop into point source mode and that segments volume will drop off rapidly as you move away from the speakers. I wish Maggie would make their big speakers 8 feet tall, actually 7' 10".
The room is 16 X 60 feet sort off. The system spends much more time playing music but it does TV and Theater duty. I have no need for rear speakers or a center channel. I have a digital preamp which includes room control and the best bass management ever made. I can adjust cross over points and slopes on the fly. I have up to 10th order slopes and the cross overs can be adjusted in 1 Hz increments. I also have complete control over levels. Thus I only need passive subs and I am much happier choosing my own amps. The only unit that comes close is the Trinnov Amethyst. There are stand alone digital bass management systems out there. I believe DBx makes one. Sanders uses it in his speakers. There's another one who refuses to make his speakers taller. Talking about bad recording engineering. I was just listening to Neil Young's Harvest. The snare drum is right in your face and Neil and his guitars are like 50 feet behind. Pretty surreal. |
Following doctrine gets you absolutely no where. Good for you. I started messing with subs because I knew theoretically they should be a huge benefit particularly with a planar speaker that has limited excursion capability and is a dipole. I would be happy to send you a picture of the whole array. It is set up on a radius from the listing position forming a segment of a circle. The subwoofers are position so that the face of the driver is in the null of the ESLs which is directly to the sides. Dipoles have a figure 8 radiation pattern. Even without room control this works pretty well but without digital bass management, given my experience you are sunk. All the amplifiers are downstairs on a shelf up against the ceiling right under the speakers. The ESLs are 3 feet from the front wall and the subs are positioned so that their drivers are right up against a wall two between the ESLs up against the front wall and two to the outsides up against the side walls. Acoustically these subs are acting as one big driver 16 feet wide forming a linear array of infinite length. Linear arrays like the ESLs do not radiate to the sides, up or down. This is a huge benefit preventing as least 4 of the primary reflections in the room. The result is that no matter where you go in the room except right up against the walls the bass output at any frequency is the same. No standing waves that you can hear. You can not tell there are separate subs in the system. the presentation is one big whole or rather all the speakers disappear. The only disadvantage is that you can tell exactly how bad most recordings are engineered. |
Tim, I think you need to drop your Adderall dose:) Sub woofers are not more prevalent in high end audio because they add expense, they take up space and women do not like the looks. Not to mention that there are still many audiophiles who think sonically they are a detriment. All this seems to go the way side when you are talking about theaters. Back in the 70s when I started using subs (RH Labs) I got all kinds of flack from the audiophile community about how they were impossible to integrate and sounded awful and how could I do that to my system la di da. Actually, back then they were right. I started off with one sub and now matter what I did I knew I was listening to a box between my ESLs. So I got another sub and mounted the ESL panels on top of them which made a distinct improvement but I could still hear the cross over. All we had back then was the Dalquist DQ 1. So I spent the next 2 years messing around with the crossover. The system could be impressive but I never though it was accurate. In 1981 I had to move from Miami to Akron so I sold the system to my room mate who had no idea what he was listening too. In Akron I got a set of Acoustat 2+2s and a set of Krell KMA 100s.
In the small apartment I was in I never felt the need for subs with this system which was glorious. In 1987 I sold just the speakers and moved back to New England where I got a pair of Apogee Divas, all the rage at the time. The Divas did not do low bass and I felt that the speakers would sound better if I subtracted the very low end from them. So, I got a pair of the early 12" Velodyn Subs. They were sort of OK but the Divas really perked up. I could never really integrate the subs well enough that they disappeared. Then I got my first TACT preamp with full digital bass management and room control. Instant bliss, huge improvement. But, the two woofers could not match the power of the Divas. Analyzing the situation I realized that the only way I was going to get sub woofers to match the output characteristics of a linear array was to make a linear array with the sub woofers. We are now in the late 90's I think. Looking at the subs available on the market then there was not one that suited my purpose. All I needed was a passive sub. So, I built 4 subs using what is now called the Ultimax 12" sub woofer by Dayton. The enclosures were made of solid surface material laminated to 1" MDF and designed with a Q of 7.4. Each one weights almost 200 lb. I got commercial 1200 watt/ch AB amps with damping factors of 500 into 4 ohms, one for each channel. The subs were arrayed across the front wall at 5 ft intervals but off the wall. This resulted at least 10 db standing waves in the room. I had to get rid of the reflection off the front wall so I spun the middle subs side ways and pushed them right up against the front wall facing each other The corner subs were already against the side walls. The standing waves all but disappeared. I re calibrated the room control and after five minutes of listening to Return for Forever's Romantic Warrior I knew I finally had it licked. That was with a cross over at 100 Hz I eventually took it up to 125 Hz. Around 2000 I was asked to do a system on the Cape for a friend of my Brothers who I had set up with Acoustat 2+2s years before. He decided to go with Maggies and new electronics (less selfish). When I was finished I was walking out the door and he asked me if I was going to take the speakers. "Do you want me to sell them for you?" "No, you can have them." So, I inadvertently waltzed into a pair of mint 2+2s. I sold the Apogees and have never looked back. I guess the moral of the story is that it takes a lot of screwing around to get things right. |
It is not only phase but arrival times that are important. Two woofers can be in phase at a specific frequency but if one is say 15 feet from the listening position and another 10 feet from the listening position the arrival times will vary and the woofers will be out of phase at all other frequencies. This will muddy the bass and soften the impact of bass drums and such. You can fix this by using digital delays on the speakers that arrive first so that they all arrive at the same time but this works only at one place which is really all I care about. Everyplace else in the room is "background music." There is more to consider than just acoustics. The best approach is to make the woofers function acoustically as one driver which they will do as long as they are within 1/2 wavelength of the highest frequency you care to reproduce. So if you are crossing at 100 Hz the woofers should be no farther than 5 feet apart giving an array 15 feet wide. Below 100 Hz this array will function as one driver giving you one arrival time pretty much anywhere in the room. Now you just have to adjust the arrival time to match your satellites which you can easily do with a tape measure. Try it. |
4 JL Audio Fathom V2. That should scare your neighbors to death. |
