Alpha LS (Possibly the coolest DIY speakers ) (1 Viewer)

[Rick Evans]

http://www.gr-research.com/AlphaLS/Alpha.htm These Alpha LS' look so cool... has anyone ever listened to a pair? I did plenty of searches on various fourms but haven't found any comparisons. What are everyone's favorite DIY speakers I'm Leaning towards the A/V3 from GR instead of 281's just so these bad boys will be timbre matched.

 

[Hank Frankenberg]

Thanks for posting. I veneered them in Padauk, which was Danny's choice. They were a very time-consuming project for my one-person effort, but anyone can build them with some help to handle them once the various panels start being assembled. I'd recommend that a customer get quotes from local woodworkers/cabinet shops in order to avoid high crating and shipping charges.
They sounded great the Saturday morning we finished installing the drivers, and I think Danny may have tweaked the crossovers since, so I want to hear them again! I think I'm sold on line sources!

 

[Brian Bunge]

We should all start praying towards Austin several times a day!
Brian

 

[Pete Mazz]

If they are actually crossed over at 1375 Hz, it would seem to be too low for the vertical spacing of those drivers. Of course this is new territory for me....

They do look great Hank. Nice work!!

Pete

 

[ThomasW]

Pete

We've measured the little Neo-8's, they can be used as low as 600Hz with an appropriate XO design

 

[Danny Richie]

Thanks for noticing them Rick.
For a few more first hand perspectives go here: http://www.audioasylum.com/audio/spe...ges/71360.html This guy mentioned them in a review. I believe he also has them on his wish list that he hopes to make reality this summer.
Then go here. This guy heard them at Gary Dodd's house.
http://www.audioasylum.com/audio/spe...ges/72737.html
Gary Dodd can be contacted at [email protected] He has a pair.
There is also info here: http://www.harmonicdiscord.com/forum...140&forum=34&5 This site has some info before and after completing the design.
Pete on the crossover just the opposite is true. Crossing them lower is no problem. Crossing them higher will get you into problem areas where as there would be comb filtering effects on the woofers.
ThomasW is correct. The Neo 8's can be crossed lower. I have used them with a first order electrical network crossed at 875Hz.
Hank if you, or anyone else, would like to give them a listen you are welcome to come on over.

 

[Rick Evans]

On the website it says that they are more suited for a larger room. What would be the smallest size room that you would recommend these in? Also how far apart should these be placed?

 

[Bryan Michael]

would they work for a ht and could you just buld a 3 rd and put it horsonaly that would be cool buld the center a little bigger and make it span from main to main

 

[ThomasW]

Thomas, if you are willing to share details I am all ears

What do you want to know?

They have a pretty big on-axis spike at 10Khz, it flattens at 15 & 30 degrees off-axis. Some designers are using a notch filter to lower the spike. IMO that's a mistake because the filter will cause a hole in the off-axis response.

Also like most wideband planars they have a relatively soft top end. Again IMO, they need a super-tweeter/super-tweeters to help augment the high end output.

Since they only work effectively down to about 600Hz, one will have the usual integration issues associated with hybrid designs.

 

[Danny Richie]

Actually Thomas,

The spike in the Neo 8 response is more around 13kHz.

Using 8 of them in a row the comb filtering effect reduces the peak to no more than about a 1db bump.

Also measuring at 10 feet away I still show the response to be flat at 16kHz. It is after that point that the highs begin to roll off.

I can still hear test tones to 19,500Hz last time a checked.

Listening to the Alphas I don't miss the last half of the top octave at all. it is not gone after all. These do play beyond 20kHz. It is just down in sensitivity. Little information is there anyway. I see no need for a super tweeter.

Also if I were to have allowed the Neo 8's to play down to the 600hz level, which could have stressed them some, integration with the woofers may not have been so easy.

But, with the slopes I am using and with a cross over point at 1,375Hz they blend quite well.

Rick,

As for room size nearly anything is possible.

I would not have thought them to work well in a small room. They could easily overload a small room. But Gary Dodd's living room is on the small side. It can't be more than 13 or 14 feet wide and maybe 14 or 15 feet deep.

With a little positioning and some room treatment maneuvers they just about disappear in his room. Sonicly that is. Visually they are a bit of a stand out.

Can a matching ceter channel be made? Sure, but it will not be a line soure.

 

[Pete Mazz]

Danny,
Yea, I had a brain fart there. :b

How are you powering the line? Uniformly or tapered? Thoughts?

God, I'd love to hear these!!!

Pete

 

[Jon Hancock]

Do you have measurements of these posted, particularly for the Neo8 line array?
I did some measurements of just two in a vertical array, for a friend who was interested in them for a media speaker. These were mounted on a 2' X 4' dipole baffle, to try to keep LF baffle loading issues at bay.
They have about a 6-7 dB rise at 13 kHz, and roll off steeply above that. 30 degrees off axis, they're pretty smooth out to about 16 kHz, but if the array tames the on axis response at 13 kHz, I'd expect the off axis to suffer a bit.

Are there any posted measurements of the complete system or the Neo8 line array? I'm not so keen on buying 6 more just to satisfy my curiousity....
Regards,
Jon

 

[ThomasW]

JohnQ

Xmax in the Neo 8's is not a significant design consideration. Unless you want to place an order from the mfgr for 5000 pcs you're limited to the stock design (hey they're only $15ea in that quantity!).

Brian Cheney uses a custom design with an additional 2mm of Xmax, but he won't sell the raw drivers to the general public or so he says. In his larger designs Cheney uses a rather unique 166Hz XO point for the Neo 8s. He then augments their output with that from 10" driver that overlaps the planars in the low range.

Recommended XO would be a high order Elliptical design.

I'm pretty sure Jon would be pleased to take you up on your offer. He's got a full Clio-Win set up with a lab standard B&K 4133 mic

 

[Dennis XYZ]

Hi guys, long time lurker, first time poster.
I think Brian Cheney is using a modified version of the Monsoon/Sonigistix drivers rather than the BG's. He claims they are better in every way and, of course, Brian never exaggerates. I've never seen the raw drivers for sale but you can get the MM-2000 multimedia system for about $220 from Dell. That's less than the cost of 4 BG drivers and it includes 4 ribbons, a 6.5 midbass, 2 6.5 PR's, and 5 amp channels (4x60 and 1x100). Looks to me like you could gut a few of those systems and build a nice line array system pretty cheap.
Link Removed
http://www.3dsoundsurge.com/reviews/MM2000/MM2000.html
Food for thought.....
Dennis
[Edit: use the spell checker, dummy. ]

 

[ThomasW]

Brian has stated on a couple of forums that he's using the Neo8's. (They're made in the far east for B&G by Denshli). And that his are 'modified' for higher Xmax. Whether Brian's info is accurate or not actually isn't important; since the the only access the general public has to the Neo8 drivers are via Parts Express, Danny, or Bob Reimer in Canada.

 

[Dennis XYZ]

Brian has stated on a couple of forums that he's using the Neo8's.

Thomas, I believe you are jumping to an incorrect conclusion based on a confusing name. Brian uses Neo 8 as a generic description of his drivers. Here's a quote from the man himself. "The current ribbon mids (designed not by me, but by engineer Dragoslav Colich) we use are the best such transducers I have heard: wider range, cleaner, lower distortion, higher output, faster due to low mass and lots of Neodymium motor." Dragoslav Colich is or was a Monsoon employee.
A picture is worth a thousand words.
Link Removed
Monsoon driver
BG driver
While Brian's drivers are not available to the public, I believe you will come much closer with the Sonigistix PTR-2000 than with the BG Neo8.

 

[ThomasW]

Dennis
Interesting....
I'd say his use of the term 'Neo8' (probably copyrighted by B&G) is more than misleading, it's fraudulent.
FWIW, the tweeter in the first photo is the spiral cut ribbon. Those are avialable for $5 ea in quantity from the mfgr or $35ea from http://www.e-speakers.com
I have no interest in obtaining the speakers Brian's actually using. I have some Neo8's and am trying to decide what to do with them.
Thanks for the info.
Regards
Thomas

 

[Jon Hancock]

Jon Hancock, I have 8 of them and I am in Berkeley, perhaps I could bring them over to your place one weekend for some measuring, if you like? Perhaps we could also measure four in a row as well, as that is how I will be using them

John,

I'd be interested in doing that. My daughter's graduation is coming up, so I'm pressed for timein the next couple of weeks, but after that it would be interesting to work something out. Actually, I'm interested in what 4 in a columne would do, too. I'd suggest we make a simple 2' X 4' baffle with asymmetrical mounting to distribute the edge effects, and measure them as a dipole. Interested?

Regards,

Jon