Acoustat six plus BG Neo8

[PHP143]

Hello, New project coming up!

First to introduce myself. My name is Bob and I live in Connecticut. 53 yo audio enthusiast. Doing it for a long time. Rarely change equipment. Have discovered that room meaurement and room treament is the key to great sound :T . Thank you Home Theater Shack REW and Ethan Weiner Real Traps :T !!!!!!!

I have been using my Acoustat 6s for about 20 something years and before those a pair of Acoustat 3s. I run the Acoustats with a pair of Acoustat direct drive tube amps.

They are crossed over to a pair of DIY subs using 16 eight inch Eminent custom order drivers per side. There are 8 forward and 8 rearward facing drivers in a sealed enclosure with a Marchand Bassis to control the low freq rolloff. They are in a stereo pair for a total of 32 drivers! The amps are a pair of SAE 2400Ls with each sub getting one amplifer each. The left channel of one amp drives the front 8 drivers and the right channel of the same amp drives the rear 8 drivers. They are further controlled by a Behringer EQ, with REW for measurements.

The crossover is a 2 way Marchand XM126 tube type with separate power supply. It will be converted to 3 way to add the Neo8s.

The room is fully treated with membrane type bass traps along with broadband traps (ala, Ethan Weiner Real Traps plans) there are a total of 30 something 2'x8' traps.

I use this system for vinyl only with a VPI TNT turntable and Eminent Tech ET2 tonearm.

That completes most of the "hello there".

I currently have 10 Neo 8s on hand and will buy the other 10 Neo8s soon. Of course I have quite a few questions on setting up/designing/tuning the Neo8s in my system.

The first thing I need to do is build the frame and install the drivers and wire them so I can drive them with a spare SAE 2400 amp that I have. Therein lies my questions.

Being that the first thing is to build the frames lets address that first. As they will be in their own frames set somewhere along side of the Acoustats I need to design a frame for the 10 per side Neo 8s. Do I just mount them to the face of the frame and is the frame a certain width and is it beveled etc? I have seen them wider on the bottom than the top, I like the look, but is this necessary, better, different? You get the idea. So let me know your ideas on frame design.

After the frame is built I will need to wire them so I can drive them with the SAE amp initally and the at some point will probably use a nice stereo tube amp. So any thoughts on how to wire them will be useful at this time also. I expect that they will be crossed over around 2500 to 5000hz.

Here is a link to my system and other things in my life on Webshots.

Images not available

Bob
PHP, Octave Doctor
If the first 100db sucks, why continue?

[ThomasW]

Hi and welcome, always good to hookup with another Acoustat owner..... :T

Each side of my mains have a pair of Acoustat 1+1's separated by a B&G RD75 and a line array of 16 Technics leaf tweeters. XO points are 80Hz-630Hz for the Acoustats, 630Hz- 6khz for the RD-75 and 6kHz and up for the leafs. XO is currently a highly modified XM-9, this will soon be replaced by a fully custom unit based on the Marchand XM-44 motherboard.

My RD75's are simply bolted to two pieces of alu angle.

Here's a pic of my system before I added the RD75's. The leaf tweeters are mounted in alu mullions used for store fronts in strip malls. Obviously not a good system for dipole drivers like the Neo8 or Neo3

Image not available

This thread shows Chasw98's line array under development. He's using Neo8's and Neo3's, with an aesthetically interesting baffle system for the planars.

[PHP143]

Hello, Thomas and everyone else! Yes, I have been purusing this site (and others!) for info to glean for my project with the Neo8s. I have looked at some of your past posts as well as Chasws and will continue to do so. Of course there never seems to be a consensus on how to do things and there seems to be very little official info.

I do have many other questions and will probably have quite a few more as I progress with this. I hope to have it completed within 3-4 months.

Looking at Chasw frame and not using the Neo3s would I just use a frame that is perhaps 2-3" wider than the Neo8? How thick should the frame be? Is 3/4" plywood too thick? Or too thin?

Should I use aluminium to streghten the frame?

Bob

[ThomasW]

All the B&G drivers are a pain to mount since they're pop-riveted together.

Were I working with Neo8s I'd first attach them to alu angle or strips. Then attach that assembly to thicker baffle material.

Much to Chasw98's dismay I'm going to hot glue the Neo3's in my line array into 1/2" X 1/2" alu 'U' channel. Then attach the 'U' channel to the baffle.

[chasw98]

Yes, much to my dismay he is going to hot glue them. Oh well......

Bob, depending upon how handy you are with tools, I would go the route of mounting them in an aluminum channel, or what I did, 1/4" plexiglass. The plexiglas is fairly easy to work with as far as routing it out to fit Neo 8's and Neo 3's. I used a pice of 1/8" flat aluminum bar behind the plexi that was drilled and tapped to mount the drivers to it.

One thing I found very hard to do was to decide what the distance was between the drivers in the vertical plane. Should they be 1 inch apart or more? How far away from the woofer should they be? I found it very hard to simulate an array on the computer. I ended up building 3 or 4 test baffles and measuring them to get a feel for what would work best. Then I just went for it and built it using the plexiglass. They are playing right now and sounding extremely good. I am very, very pleased with them.

Keep asking questions and I will give you the benefit of my experience as little as I have.

Chuck

[PHP143]

Hi Chuck, If I go with a piece of 1 1/2" thick bonded plywood or hardwood with a 2" wide baffle, should the baffle be beveled? Is the baffle wide enough? Should one side be wider than the other?

Thanks,
Bob
Octave doctor, PHP
If the first one hundred db suck, why continue?

[fjhuerta]

I used silicone to mount my Neo3 & Neo8's to an aluminum plate, which I then screwed to my baffle...not the most elegant solution out there, but it worked perfectly well, and doesn't look half bad.

[chasw98]

[QUOTE=PHP143]Hi Chuck, If I go with a piece of 1 1/2" thick bonded plywood or hardwood with a 2" wide baffle, should the baffle be beveled? Is the baffle wide enough? Should one side be wider than the other?
[QUOTE]

Bob:
A picture is worth a thousand words. Here are some shots of the front and back of my Neo array. When you talk about beveled, I am not sure where you might mean beveled. You can bevel the edge from the front view meaning the border or edge of the baffle. Mine is not beveled yet. I plan on beveling or rounding it when I get to the finishing stage.
You can also bevel a relief behind the baffle to alow the back side to open up more. I did not do that because it would cost me gripping surface for mounting the plexiglass into the wooden baffle and in my mock ups made earlier it did not seem to be a large factor in quality of sound.
Should one side be wider than another? Logic tells me that, yes, one side should be larger. You can use a Baffle difffraction program to see some effects that would occur with individual drivers and their placement but how it translates when using an array is anybodys guess. I am sure there are some people much smarter than me who could give a more definitive answer. Personally I found that there is not much information on array building out there. Lots of theory but not much practical. I used a lot of common sense and got advice from some very intelligent people. I found more useful information from building high frequency antenna arrays than audio info.

Here is what my array looks like from the front.



Here is a closeup of the mid/hi section from the front.



Here is a closeup of the rear of the mid/hi section showing the aluminum bars and the plexiglass inset.

[Paul W]

I'd mount them as close as practical to the ESL panels. Consider changing line height to 9 or 12 drivers. Though your SAE amp probably has enough voltage swing for 5x2 wiring, 10 drivers is a bit of an odd duck for impedance. Power tapering is a possibility but that might not match best with the ESLs.

[PHP143]

Hi Chuck, Why go through all of the work with the plexiglass, the aluminium frame and masonite frame? Why not just screw the drivers directly to a wood frame with either wood screws or machine screws with a nice gasket inbetween? Am I missing something?

Bob,
Octave doctor PHP
If the first one hundred db suck,
why continue?

[PHP143]

Hi Paul, actually you are correct I may be getting ahead of myself with designing the frame as I may need more or fewer drivers.

I chose 10 drivers per side as it works out well for a few reasons except as you stated, impedance.

I could use 9. they would be 16 inches shorter than the Acoustats.
I could use 10. They would be 8" shorter than the Acoustats.
I could use 11 = same height as Acoustats
12 is 8" taller than the Acoustats.

Is 9 panels my best bet as far as a compromise between height vs. impedance?

Though I have given athought and know little about an Autotransformer to alter the impedance. Like this,

http://www.zeroimpedance.com/

Is this something that would work for me?

Bob

[ThomasW]

With mid/tweeters you don't need a floor to ceiling line length like one does the woofer section of a line array.

Since you're using an active crossover I see no need for an autoformer. The load presented by the Neo8's is pretty benign.

It's easier to mount and wire the Neo drivers on thin material.

If thicker baffle material is used the drivers must be mounted from the front to avoid edge diffraction issues. Then the sides of the back side of the baffle cutout need to be lined with sound absorbent material.

[Paul W]

Nine in a 3x3 array will present a four ohm load which the SAE should handle with no problem.

Ten at 5x2 would be 10 ohms which a tube amp might like better, provided the amp has enough voltage swing. With a higher impedance load, the differences in EQ required for a tube amp vs SS may be lower. (One characteristic of tube amps is that precise EQ is usually dependent on a specific combination of amp and speaker...see Stereophile measurements of frequency response and distortion for tube output & SS amps.)

[PHP143]

Hi Paul, Thanks for the info...mmmmm I probably should not set anything in stone yet........... Are you saying the SAE amp will not be happy with a 10 ohm load?

I do believe, that at some point, I hope to use a low power (less than 25 watts) stereo tube amp or mono blocks. My other choice is two stereo amps with each amp driving one channel. Dose anyone think there is an advantage to using any one of those configuations as far as power goes? I prefer to use dual mono where ever I can.

Also I don't want to go into "analysis paralysis" and I do realize that I can change things later on and will make provisions for that. My inital frame will be a prototype/temporary unit.

I will have to see what I end up using for an amp or amps. Anyone care to guess how many watts I will need?

I reserve the right to make changes, any time I want or if I make a mistake!

Paul, I saw a post where you asked about an LP with Flamenco music that was used as a stereo test record "back in the day". I would bet my best pair of underwear that it was "Hi-Fi A laEspanola" (or something like that) , which I believe was a RCA shaded dog label.

Thanks,
Bob
PHP143
If the first one hundred db suck, why continue?

[Paul W]

Bob,
No, not at all...the SAE should work well at 10 ohms. (I originally Assumed the Neo 8 was an 8 ohm driver and a 5x2 array would yield a 20 ohm load...beginning to get a little high for power delivery. I later looked at the Neo 8 specs and it is 4 ohms, or a 10 ohm system load.)

Thanks for the tip on the Flamenco track...a-searching-I-will-go!

[Bill Schneider]

I would bet my best pair of underwear that it was "Hi-Fi A laEspanola" (or something like that) , which I believe was a RCA shaded dog label.

Close, but that title is on a Mercury Living Presence label. It was recorded in 1953 and 1959 according to a CD release that I have from ArkivMusic.

[PHP143]

I just built my prototype frames and have installed 4 Neo8s each side wired for 4 ohm. I am using a vintage Onkyo receiver to power them full range to break them in and to give them a listen. I must say that even with just 4 drivers per side and run full range they are already impressive.

I will be ordering the other 8 Neo8s today as I have decided to use 9 per side ( I have 10 drivers allready ) and run them at 4 ohms. I will then continue to listen to them with the receiver. I need to send my Marchand XM126 back to Marchand to have it converted to 3 way.


Should this line array be vertical or should there be some degree of tilt back?


Thomas, have you ever done a freq response of your Acoustats run full range? I am particularly interested in the high freq response and their -3db point. Also where do you cross over the Acoustats to the Neo8s? I initially thought that 5,000hz would be a good crossover point to my Acoustat 6 but am now beginning to think lower....2,500hz?

Bob,
PHP

[PHP143]

Hello, I just ordered the eight Neo8s

This is going to be fun!

Bob
If the first one hundred db suck, why continue?

[ThomasW]

Thomas, have you ever done a freq response of your Acoustats run full range? I am particually interested in the high freq response and their -3db point. Also where do you cross over the Acoustats to the Neo8s? I initally thought that 5,000hz would be a good crossover point to my Acoustat 6 but am now beginning to think lower....2,500hz?

It's long lost but yes I ran a FR plot of the Acoustats many years ago. It's what one typically sees with an ESL, slow roll-off starting just below 10kHz. Mine had a added bonus feature of a spike at 1kHz caused by the fact that my panels are joined together at an angle.

IMO the Neo8's are mid-tweeters not super tweeters. It's pretty easy to see their issues at higher frequencies.



I don't use Neo8's in the system with the Acoustats, I use RD75's. One reason for this is Neo8's didn't exist when I looked around for a planar mids. The RD-75's have always been used with a 630Hz XO point. Although rated down to 150z, Jon and my testing clearly indicated they sounded better when run between 500-650Hz.

Were I using the Neo8's I'd use the same 630Hz crossover point. Using either the Neo8's or RD75's as the midrange, there's a wider sweet spot since the radiating element is narrower than the Acoustat panels. This is the counter-intuitive situation that confuses most people. The tendency is to think the wider the planar the wider the sweet spot, when in reality the opposite is true.

[PHP143]

Hi Thomas, Thanks for the reply. I am very curious as to how you came upon 630hz crossover point. Are you using the Acoustats for all freq below that? A two way system? Do you have full range measurements of your system now?


If I were to use the 630hz crossover along with the 85hz crossover to my subs then the Acouststs are barely delivering one full octave of music when you factor in the rolloff to the crossover point. Too late now but perhaps I would have been better off just using Neo 3s?

Should the line source be vertical or have tilt back?

How do you post pictures on this site?

Bob

[PHP143]

OOOPS found the attachments!!!

Here is a REW of my system no smoothing out to 2,000hz. I use the freq limited Radio shack meter an will at some point start use full range measurements.

Also attached is a picture of myself standing next to my DIY 32 driver subs under construction.

Bob

[PHP143]

I did not realize the REW only went to 131hz here is the rest of the measurement from 131hz to 1.3khz.

Bob

[JonMarsh]

Hi Thomas, Thanks for the reply. I am very curious as to how you came upon 630hz crossover point. Are you using the Acoustats for all freq below that? A two way system? Do you have full range measurements of your system now?


If I were to use the 630hz crossover along with the 85hz crossover to my subs then the Acouststs are barely delivering one full octave of music when you factor in the rolloff to the crossover point. Too late now but perhaps I would have been better off just using Neo 3s?

Should the line source be vertical or have tilt back?

How do you post pictures on this site?

Bob

Hey Bob,

Not to be too much of a curmudgeon (that's Tom's job), but I suggest that considering the crossover, you're not really looking at things with the right perspective- to use a driver in a given range with X and Y crossover points accurately, especially with an active box crossover with standard filters, the driver must be performing well to an octave below the low crossover point and an octave above the high crossover point for correct integration and phase performance in the crossover region. So, in ThomasW's system, the Acoustats must function well from 50 Hz to 1250 Hz. Last time I checked, that's 4-1/2 octaves. :W

[PHP143]

Hi Jon, Well I can be a bit of a "crumb-mudgen", its similar to a curmudgen except a little flakey

I said if "I" were to use a 85hz crossover point to my subs the -3db point is 120hz and a 630hz crossover to the Neo8s the -3db point is 500hz I would only be using the Acoustats for around two octaves. Not one octave as I stated, if I were using the start of the rolloff it would be one octave.

I don't think the Neo8s have nearly the panel surface of the Acoustats and should not be replacing them as midrange panels. At least not Acoustat six.


You said that there needs to be an octave of overlap for the crossover point. As for as I can see from the look at the provided manufactures freq response they are barely able to do 630hz. Probably 6db down at that point.

I would be surprised if they are able to do 1600hz. I believe a good place to start,for me, would be 3200hz and above. Which is somewhere around where I originally thought. :roll:

My Acoustats -3db point is 120hz with a gradual roll off starting around 200hz. So no I dont think they do 50hz.

Bob

[ThomasW]

We're not in the habit of overtaxing drivers. The mfgr's plot of the Neo8 is taken in free-air. Earlier in this thread I posted a link to Chasw98's build since he has measurements of them mounted in a baffle....

[PHP143]

Hi Thomas, OK so now I see it!

And with that measurement they sure do look more mid range. Though I will still initally try them in the upper end. Of course I will keep all posted to my progress over the next 25 years of tuning/experimenting/playing with them!

Bob

[PHP143]

Hello, just a couple of picks of my Eminence custom drivers that I use in my DIY subs. They are currently crossed over at 85hz with a Marchand XM126 tube type with a separate power supply.
An internet friend had these made in a lot of 100. This way three pairs of subs could be made at a reduced price for buying 100 units. Each pair using 32 eight inch drivers. This was my first speaker project.


Bob,
Octave Doctor PHP

If the first one hundred db suck, why continue?

[PHP143]

Hello, I just recieved my final 8 Neo8s. I have been running four Neo 8s per side fullrange just to hear them.

I now need to wire these for a 4 0hm load. Would some one send me a wiring diagram to obtain this with 9 drivers per side.

Thanks,
Bob

[Dennis H]

     |4|  |4|  |4|
(+)--|4|--|4|--|4|--(-)
     |4|  |4|  |4|

[PHP143]

Hi Dennis, Thanks, they are up and running!

I listened to them using my turntable, run through my vintage reciever. Since that handled the load/speakers without a problem tonight I will run with my turntable/phono preamp/stepped attenuator to the SAE which will drive them till I obtain a nice tube amp for them....

I want to listen to them on their own for a while to get a feel for their sound quality and to break them in. It will be a while befor I can afford to modify the Marchand crossover to 3 way.

My initial impression is that I would keep them out of the range of voices and the "body" of instruments.

The SAE amp has meters so I will at least have some idea of the power they use.

Thanks,
Bob
Octave Doctor PHP
If the first one hundred db suck, why continue?

[PHP143]

Hello, Just to let everyone know that the Neo8s that I recieved from Parts Express are cosmetically different from the ones I bought previously (several months ago).

They are a slightly darker black.
The rivits are black instead of silver.
There is only one speaker terminal as opposed to the previous two wire spades.
They say on the little white label "dneo8" previous "neo8".
I assume the changes are the "D" revision.

Bob

[PHP143]

Here is a photo of my Neo8s in the frame I made. This is with four drivers.
I will upload a picture of them with all of the drivers set up, well as soon as I take one.

Bob

[PHP143]

Hello, Here are a few pictures of the almost full array of drivers in their frames. I have one space remaining on the bottom of the frame for a tenth Neo8, which is the way I think I will go and then wire them for a 10ohm load.

I have been listening to them but they are still running without a crossover, so they are still full range.

I will call Marchand this week and see how much it will cost to convert my XM126 to three way and when they can do this.

My Radio Shack meter just died which will give me the motivation to buy a full range calibrated mic for REW measurements.

Bob

[PHP143]

HI just doing a test on picture sizes.
Bob

[PHP143]

Hello, I am looking to order some parts from PE. I would like to order wire, to wire the drivers. What gauge wire should I use? If possible please provide a part number.

Thanks,
Bob

[ThomasW]

As is seen in Chasw98's thread we generally recommend the Mil spec wire from ApexJr

http://www.apexjr.com/wire.html

[PHP143]

Hell O, will be posting no more threads, questions, pictures or any thoughts as apparently everything you need to know is posted in on of Chasws 482 posts

Thanks,
Bob

[Johnloudb]

Hell O, will be posting no more threads, questions, pictures or any thoughts as apparently everything you need to know is posted in on of Chasws 482 posts

Thanks,
Bob

Sorry to here that. I've been checking in on this thread on occasion and enjoy seeing your build progress. Thomas was just answering your question and giving a reference to a similar build, using the same drivers. I'm positive he's not suggesting that you shouldn't have asked. The 18ga. wire in the link above should work fine.

[---k---]

I've used the 14 ga from Apex Jr. Solders real nice. I like it.

I've also used Dayton 14 ga speaker wire from PE. Works well too. Nice fine stranded wire. PE's website is down right now.

I've also used cheap 14 ga wire on small 20' spindles Menards automotive department. Not as fine stranded as either of the other options. If you believe copper is copper, this is the wire for you, as it this is the cheapest 14 ga wire you can find.

[capslock]

These Neo 8 drivers look suspiciously like those in this thread:

http://techtalk.parts-express.com/showthread.php?213726-B-amp-G-Neo8-Knock-Off

Apparently, there were Chinese copies sold in 2009 before the 8s became available.

[MrAcoustat]

Acoustat DIY Spectra 8800 41x102x10 inches just about 800 pounds each.



More photos here - - - - - http://www.flickr.com/photos/mracoustat/