Acoustat panel angles? 8" vs 9" panels?

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I read a couple old reviews of the Model 3 & 4 (as opposed to the Monitors) and both said the lower panel angles of the Model 3 & 4 (9 and 6 degrees respectively) made for smoother response, particularly the Model 4. I'm preparing to build new frames for my various panels and I'm wondering how much I should concern myself with this. The 3 panel pod from the X was going to be my starting point but these reviews have me questioning this. I'm probably (at least initially) going to shoot for a 4-wide array at floor level with a single panel above. My thinking is that for most of my listening the lower portion should be fine but the extra panel (possibly involving on/off switches) could be positioned for when I'm on the stationary bike or standing while exercising. I'm also considering trying to build the frames to have some ability to alter the angles to try to tune the arrays to the room. Any thoughts?

Also, the 3 & 4 wide arrays used a combination of 8" & 9" panels. I have plenty of 9" panels but only two 8". At this point the 4-wide array would have one 8" per channel. Think this will be problematic?

Thanks!
 
I have experimented with this.

What I built was a "non-frame" to hold the panels with long "piano hinges" between the struts that went behind the panels, I could angle the panels as I wished. I did this with 3s... I also owned 2s, 1+1s and IVs...

They are much much more directional than they appear to be when listening in a room. I ran them outside as an experiment - no highs off to the sides at all!!

The height above ground will definitely effect the bass and mid bass, floor bounce or lack thereof will be an issue.

Adding in a 5th panel may be an issue, as there is no "tap" for the 5th panel... although that may not be a big deal... I think I'd just tilt them back a little, which is kinda how they are set up anyhow...

you were going to stand the 5th panel straight up??

It would probably be better to use all 9" panels if you can... but adding in a symmetrically placed 8" panel seems ok.

I think the panel angles have more to do with soundstage and how you hear the panels than anything else. The bigger the speaker - like the IV, the better the LF response. I also heard the 6s... dual Mk121s, quite impressive, big tall room though...

_-_-bear

PS. stiffness of the frames counts. As does freedom from vibration.
 
Thanks, Bear! Could you please be a little more illustrative about those frames you built? Have pics? :)

The plan at this point is to make a 4-wide array (ala Monitor 4 or Model 4) but at floor level, not raised off the floor. I want to add at least one panel vertically so I can maintain good high-end response without having to remain seated. I figure the ideal panel angles would be dependent upon the seating distance, which is why I'm becoming more keen on trying an adjustable setup to find the best arrangement. Once that is sorted out I'd build a more permanent frame setup utilizing the optimized angles.

I have an extensively modded set of Medallion interfaces but I'm currently focused on using my servo amps. I suppose I could even try a combination of servos & interfaces, having each drive some of the panels.
 
I'm not sure what you meant, when you stated that you were looking for a new improved direct replacement that must sound the same as the old,but better?
But, I think I know what you mean.
My design, as well as others, is a much improved version upon the acoustat design.
Although I have never heard or have had any experience with the acoustat system the only thing could possibly change the sound for the worst ,IMO, is by increasing the mass of the diagphram, providing you are using the original electronics and transformers.
IMO,whether you decide to rebuild panels you have or do a ground up assembly from scratch they are going to sound pretty good because you already have good transformers and crossover system to start with and this the most determining factor for the characteristics of the way they sound.
Providing that the panel capacitance's are close to the original.
Many diy'ers including my self has had many struggles with transformer issues.
The most important thing is the choice of diagphram material.
There are several good choices of coatings available also.
I personaly prefer licron crystal others like pva glue doped with black ink,graphite,elevamide a type of nylon and the list goes on.
I would also suggest to to use a .25mil or less mylar for the diagphram material.
The thicker stuff will produce a speaker that works but with much less details in the higher frequency's.
The mass of the diagphram is the main key factor.
If you read back on some of my other recent posts(ESL Diagphram coating),I have found that just by cleaning the diagphram of my little panel(which was very dirty with heavy dust and even light mud and pics to show) restored the detail and high frequency response.
So, mass was the biggest factor here.
The diiference between an 8"panel vs 9"panel is nil unless the d/s spacing is radicaly different.
Those are my thoughts and I hope they help you with your project.
If any one else has had any experience with acoustat panels feel free to jump in and correct me if I'm wrong about anything.
Good luck,keep reading and don't be afraid to ask questions. jer
 
Thanks, jer. I'm not at this time considering building new panels, just trying to go about building new frames for my existing Acoustat panels. New panels are a little too ambitious for me at the moment. :) But, yeah, I think you get my gist about the possibility of recreating the Acoustat panels so they work just fine with the Acoustat Servo amps or interfaces, yet perhaps improved upon with more up-to-date materials, etc.

AFAIK, the 8" & 9" Acoustat panels are identical other than the width. From what I've read, they used a combination of the 8" & 9" panels in the wider arrays to avoid common-mode resonances or something along those lines.

I'll keep asking questions; without this site and Audio Asylum, I'd be far more clueless than I already am!
 
As I said, tilt them back, you will not need the higher panel.
the higher panel will be problematic in all likelyhood, plus look wierd.

Ur better off building a "2+2" or if you have enough, "3+3".

If ur using servo amps, modify them by changing out the antique opamps for modern high performance ones - choose carefully.

_-_-bear
 
Thank you, bear. I have pairs of 1+1 and 2+2; I really like the double height Acoustats for the fact that they sound good whether laying on the floor or standing up. I also have a pair of the X; the tilt works OK but isn't nearly as effective as the stacked panels.

A little extra info might clarify why I'm seeking what I'm seeking: my listening room doubles as an exercise room. I'm a few weeks away from having a hip replacement so this room will play a big role in my recovery. I've never gotten the 1+1 or 2+2 to match the overall sound I used to get from my old Monitor 4 speakers, and playing around with the 3-panel-wide X has pointed to the idea that my ears probably fall more in the "wider is better" camp as far as Acoustats go. But, since I've gotten used to the taller arrays, I can't really give up the full-height aspect either. I'm trying to get the best of both worlds! :) Tilting the X gives me good sound while I'm standing or on my stationary bike but sounds terrible while I'm laying on the ground stretching. I recognize that what I'm attempting may not be ideal in the long run but if it is enough to keep me in the room rehabbing and enjoying music, that's all I'm hoping for, even if it looks like crap. The room is a stand-alone building, and I've no wife to contend with, decor-wise. I do have plenty of panels to play with and I'm sure I'll end up experimenting with a 3+3 or 4+4 setup (I guess Monitor 6/8 would be more appropriate if I continue with the servos) in the future, though.

I have been corresponding with Michael Savuto from Analogue Associates about upgrades to the servos. Mine have had the op-amps replaced (before I got them) but I am going to give his recommended op-amps a try at some point. Thanks for the tip, though. So much good info from this site's members!
 
hella356:
"AFAIK, the 8" & 9" Acoustat panels are identical other than the width. From what I've read, they used a combination of the 8" & 9" panels in the wider arrays to avoid common-mode resonances or something along those lines"

That makes sense to me.
I have a copy copy of the srevo amps somewhere and I was thinking about building them.
Can you tell me how they sound and perform,and have you ever measured the spl's using them?
Food for thought: on my little panels I seem to like the effect of angling the panels inward than outward.
It seems to widen the sweet spot just a bit with out having 2 or 3 noticeable seperate narrow high frequency beams, have you tried this ,if so what were your thoughts?
After I get an anechoic type room setup I will be able to investigate this further. jer
 
I don't have any equipment to measure SPLs or anything like that but what I'm finding is that the servos have a fuller, more natural sound than what I've gotten from the interfaces with either a Hafler DH-500 or a Counterpoint SA-100. Somehow more musical, less hi-fi. They play louder than the 100W Counterpoint but not as loud as the 225W Hafler. However, whereas the Counterpoint ran out of gas before I wanted them to, the servos do play plenty loud in my room.

I haven't tried any sort of angling yet but I'm hoping my cabinet-maker friend can help me with some creative ideas for experimenting with the angles. I'm certainly willing to step outside the norm while I play around with them (including trying the type of angling you're talking about) and will do so as much as I can.
 
Thank you for sharing with me your veiws.
That seems to be the norm so far on direct drive amps.
I plan on going that route some time in the near future.
I'm just trying to find out how much peak to peak drive voltage will be required to achieve above average performance. jer
 
Thanks again ,hella 356,for the literature.
Lots of super info.
I have already read all 995 pages.
Looked at(ha ha ha )!
The acoustat-x info was what I was looking for,and, it is all there,cool!
It's know wonder you studdered when I asked you how big are the transformers.
They'er fricken huge,correct me if I'm wrong but I thought I read 14"x8"x4".
Nice size for a fullranger. jer
 
Until I can get over to my cabinetmaker friend's place to get really crazy with some adjustable frames, I slapped together a 3+1 setup using the 3 panel pod from the X, with some extra 9" panels mounted above. The lower panels are now perpendicular to the floor rather than tilted back as they were in the X. MUCH better than the X with 1+1 standing next to it. I haven't played with placement much yet, but I think I'm on the right track and have essentially solved my wanting the "best of both worlds" for now, although I am certain there will be substantial gains to be had when my buddy puts together some better thought-out and executed frames.
 

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hella356,How do you have your panels wired together?
I find that when I Paralleled my three little panels together I seem to be getting charge migration between them at different bias level settings.
It's like having a pan control when I adjust the bias control.
Because of this it also has an effect on directionality of the three combined panels.
I think I have stopped this by putting a seperate 30megohm resistor on each diagphram connection before connecting to the bias supply.
Each panel is a little different but not by much and I didn't think that there would be any issues like this.
I'm very curious? jer
 
They are all wired together into a three prong banana plug which plugs directly into the Acoustat direct drive amp. When used with the transformer interfaces, they all are connected to single spade lugs for front & rear stators, with a pin connector for the panels. So yes, they are all connected in parallel. This is the way all non-Spectra Acoustats are set up, and - I'm quite sure - the Spectras (even with their more complex wiring) are also run this way.
 
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