[Andrikos]

Hello,
I'm in the (LOOOOONG) process of building my line arrays using 8 Vifa PL18W09's and 8 BG Neo8 PDR's per side.

Woofers
I'm building a separate SEALED box for the woofers (8" x 60" x 13.5" WxHxD) out of 3/4" Baltic Birch Plywood - 2mm of Dynamat - and 3/4" MDF sandwiched together for a total wall thickness of 1.53" all around. Needless to say this is one hefty and DEAD box. It took a ton of time and glue to put together but I'm very happy as to how it's looking/feeling.
In case you're wondering why it's *only* 60" long, the answer lies to the sheets of Baltic Birch Plywood that come in 5' x 5' sizes.

Tweeters
The BG Neo8 PDR's (have improved horizontal dispersion compared to the STD units but lower efficiency) will be fastened on 1/8" aluminum stock and screwed on on the side of the woofer tower. The tweeter will be open air and will be fully parametrically equalized

I'm using this awesome design as kind of a reference:

http://www.diyaudio.com/forums/showthread.php?postid=67864#post67864


 Since my towers are *only* 60" tall, the tweeter column will exceed that height up to my ear level standing up (I'm 6'3" so that's quite aways...)
Or another solution is to place the speakers on a marble-granite-or some other heavy ass base to make them about 15" taller. In that case the tweeter line would be flush to the top of the woofer cabinet.

Anyway, enough of that...

What will be driving these things?[/u]

I'll be using a fully programmable Behringer DCX2496 loudspeaker management system to drive the Line Arrays. The DCX will do dual duties of active cross over and fully programmable parametric equalizer using RTA.
 
I'll soon be purchasing one of the world renowned ( ) Panasonic XR45 receiver to drive the woofer lines along with the surrounds (full range TB W3 871's). No center yet. AZRyan's concept is looking really nice...
I want to drive the tweeter line with some sweet sounding (this is where the TUBE Guru's come in) amps.
I will likely be crossing over from the woofers to the tweeters at around 500-1000kHz. This is where the active programmable crossover comes in so handy... If you don't like one setting, you move on to the next. And you can save all the settings for different listening situations (i.e. 2 ch vs. 5.1)

Anyway, since the TUBE amp will only have to drive the tweeter lines, is there a good amp out there for under $500/channel and probably over $20W/channel that would give me sweet sound and dialogue legibility that these ribbon tweeters are renowned for?

Any suggestions will be greatly appreciated
Thanks,
Andreas

[vpolineni]

have you considered dodd audio?  Gary seems to offer excellent products at lower prices compared to other tube amps...

[Rick Craig]

Hello,
I'm in the (LOOOOONG) process of building my line arrays using 8 Vifa PL18W09's and 8 BG Neo8 PDR's per side.

Woofers
I'm building a separate SEALED box for the woofers (8" x 60" x 13.5" WxHxD) out of 3/4" Baltic Birch Plywood - 2mm of Dynamat - and 3/4" MDF sandwiched together for a total wall thickness of 1.53" all around. Needless to say this is one hefty and DEAD box. It took a ton of time and glue to put together but I'm very happy as to how it's looking/feeling.
In case you're wo ...

The Neo8PDR is really not very good for use as a tweeter.

[Andrikos]

The Neo8PDR is really not very good for use as a tweeter

That's what I've read about any ribbon due to their poor vertical dispersion.
If you put them in a line though, the story changes.
Am  I getting my facts mixed up here?

I have never read any complaints from Alpha LS owners as to the inadequacy of their BG NEO8's as tweeters.

And PLEASE don't use my thread as ANOTHER flame war between GR Research and Selah Audio.
We've had our fill with those.
Thanks,

edit: stupid spelling errors  

[Andrikos]

have you considered dodd audio?  Gary seems to offer excellent products at lower prices compared to other tube amps...

vpolineni,

thanks for your suggestion.
Dodd is definitely a name I'm considering.
However, I don't know anything about Gary's products I was hoping some specific suggestions would be made...
Thanks again...

[Rick Craig]

The Neo8PDR is really not very good for use as a tweeter

That's what I've read about any ribbon due to their poor vertical dispersion.
If you put them in a line though, the story changes.
Am  I getting my facts mixed up here?

I have never read any complaints from Alpha LS owners as to the inadequacy of their BG NEO8's as tweeters.

And PLEASE don't use my thread as ANOTHER flame war between GR Research and Selah Audio.
We've had our fill with those.
Thanks,

edit: stupid spelling errors  

Actually I was talking about the horizontal dispersion. The PDR version is a little better but still falls short compared to other planar/ribbon drivers. The problem is that the ribbon area is too wide and so it starts to beam in the upper octave.  This results in a lack of "air" in the top octave and restricted image width. When you compare to another speaker with wider dispersion it's very easy to hear the difference.

I'll also add that one of the speaker techs for a BG distributor has advised against using them as a tweeter for the reasons stated above. This is not an attempt to start a flame war - I'm just trying to help you out. I'll also add that the BG specs for the lower crossover point are "optimistic" at best. Hope this helps.

Rick

[Andrikos]

Rick,
now that's a response I'd like to see. I wish you'd made that point the first time around...  
Anyway, sorry for being too "trigger-happy" and I really appreciate your inputs.
Thanks,

[JohnR]

Andrikos, awesome box building there!

One question: are you sure the XR45 will work here? I thought there was no way to insert a crossover in the signal path with it.

Anyway, I had a thought in the amp department. Don't know if you want to DIY but you might want to look at the ST-35 from www.diytube.com. That comes in well under your budget and by reports is excellent sounding

http://www.diytube.com/phpBB2/viewtopic.php?p=648#648

[Andrikos]

Wow JohnR,
Thanks so much for the suggestion, it looks like a great way to get a tube amp.
The only negative I'd see here would be that is it's too time consuming.
With all this stuff going on, finding time to put together a kit would be quite difficult.
Thanks for you kind words.
Maybe I'll try and find a finished kit!

[Danny Richie]

*edited*

As for your design... I tried the open baffle deal with the Neo 8's right off the bat. It had its pros and cons, but in the end just didn't sound right.

Open backed mids maybe, but open backed highs didn't do it for me. Too much has to be done with the rear wall to control it all. The rear wall reflected energy seemed to interfere to often and muddy up the real highs.

Don't let anyone fool you on the horizontal dispersion issue. They image fine. 99% of the time you'll be adding side wall room treatment to eliminate some of the excessive side wall reflections.

Even the standard Neo 8 and Neo 3 work fine as tweeters. The element is only 1.25" wide, and the off axis response is little worse than a 1.25" diameter dome tweeter.

The standard Neo 8 will also get your output level up.

Also, the lowest I would cross them from my experience is in the 800 to 1,000Hz range.

[Andrikos]

Danny,
thanks for your reply.
That makes me feel better about the Neo8's as tweeters.
I'll try the open baffle thing and if it doesn't suit me, I can easily built a 3" deep box to tame them.

Does Gary Dodd have a website?
I can't find any info on his products other than some sporadic info in the GR Research forum.  

JohnR is right!
I don't think I can use the Behringer before the XR45! Has anybody done this?
I guess I'll keep on using my marantz receiver, pre out to the behringer and use 2 pairs of amps to drive the Line Arrays.

Thanks to all for their suggestions.
Keep them coming!

[Jon L]

That's some great cabinet work.  Would hate to see it go to waste.

First of all, I strongly advise against using 2 different amps to biamp when the x-over point is so high.  The highest x-over point that would work well with 2 different amps would be around 150-200Hz.  Even 300-500Hz is pushing it.  1k to 3K would be worst possible.  The different signatures of each amp would ruin the illusion of the "real thing," causing coherence problems, and plain irritating over long term.  Go with 2 identical amps, tube or solid state.  I use tube on top and SS on bass, and at 140Hz x-over point, I still hear some incoherence.  

Also, you might consider going with true ribbons.  Something like Fountek ribbons (Madisound) are reasonably priced and come monopole already.  If cost is a concern, I'd rather go with less number of true ribbons.  

Make sure you have access to some real testing equipment as well.  You'd be surprised how insensitive our ears are in detecting variations, even in 4-6dB range.

[Andrikos]

Hi JonL,
Thanks for your good words.

I've been thinking about your different sonic signature amp remarks in regards to crossover point. I think you're right. I'll definitely have to go with identical amplifier pairs.

 Since I won't use the woofer line below 80Hz (or so) does a tube amp have enough juice to move 8 woofers with authority and clarity?
I'm not familiar with tubes and I don't want to buy a "weakling"...

Thanks,

[Jon L]

Hi JonL,
Thanks for your good words.

I've been thinking about your different sonic signature amp remarks in regards to crossover point. I think you're right. I'll definitely have to go with identical amplifier pairs.

 Since I won't use the woofer line below 80Hz (or so) does a tube amp have enough juice to move 8 woofers with authority and clarity?
I'm not familiar with tubes and I don't want to buy a "weakling"...

Thanks,

That's the dilemma.  You could think of tube amps that do bass well with multi-drivers, but we're talking about ridiculous money.  Getting 2 of these tube amps would cost you a house.  Then again, some people don't want to go with SS for midrange/treble.  

This is why audiophiledom sucks.  Unless you're filthy rich, you just can't get what you want 100%.  Luckily, my recent auditions have shown me there are very good sounding non-tube amps.  One could insert tube somewhere (at the source, preamp) to give the system just a bit of bloom and magic with SS amps.  With so many drivers and complex impedances, you will want true "Class A" type of amps that can drive anything and double the current into less loads.  I once heard a 30 watt Class A SS amp drive the hell out of 1-Ohm woofer array to extreme volume with great punch and power.

[thayerg]

Since the line array is so efficient why not try the http://www.griffintechnology.com/products/powerwave/">Griffin PowerWave? 15W/channel of digital amplification. Less than a c-note. Or try multiple amps for biamping. Incredible bang for the buck.

[JFT]

If you do go with tubes on a budget you might want to consider the Consonance Ella. I built an Ella amp which I'm using with a pair of Linus 2's, and I'm very happy with the results. With the optional KT88's it will do 50 watts/ch, and the price is well within your budget. You could build two for about $1.5K. Also, if you get a kit amp there are opportunities to do upgrades (signal path resistors, caps, etc.) which will put it in the same sonic neighborhood as some of the $2K and over "name brand" amps from retail audio stores. Don't be daunted by a kit amp. You'll spend far less time building the amps than you will spend building the speaker enclosures. There's a thread at http://www.audiokarma.org/forums/showthread.php?s=ea1919cff733c833224070561595600c&threadid=14636

[Andrikos]

Since the line array is so efficient why not try the http://www.griffintechnology.com/products/powerwave/">Griffin PowerWave? 15W/channel of digital amplification. Less than a c-note. Or try multiple amps for biamping. Incredible bang for the buck.

thayerg,
thanks for your suggestion. I'll look it up. I'm assuming it has a good word of mouth.

[Andrikos]

If you do go with tubes on a budget you might want to consider the Consonance Ella. I built an Ella amp which I'm using with a pair of Linus 2's, and I'm very happy with the results. With the optional KT88's it will do 50 watts/ch, and the price is well within your budget. You could build two for about $1.5K. Also, if you get a kit amp there are opportunities to do upgrades (signal path resistors, caps, etc.) which will put it in the same sonic neighborhood as some of the $2K and over "name brand" amps from ...

JFT,
thanks for the great info. Very interesting!
Since I'll probably have to go with matched amp pairs, do you think the amp can drive 8 6.5" woofers down to upper bass (60-80Hz)?
Thanks,

[Danny Richie]

Does Gary Dodd have a website?

I'll just send you specifics and contact info about Dodd Audio in an e-mail or something. There was a misunderstanding with one of the moderators here, and for some reason he thought I sold the stuff, which I don't.

I would have to agree with Jon L also. Using two different types of amps while crossing the drivers where you are talking about would not be the way to go.

Other than you wanting to use active networks there is no reason to use two amps with these at all.

If you were powering a large woofer, that created a large back EMF, 150 to 200Hz and down.... yea then go with a separate amp.

Also using small ribbons like the Fountek's in this application has its limitations too. Those ribbons will not play down low at all so you would have to use smaller woofers with closer center to center spacing to play high enough to reach them without comb filtering problems within their range.

That's the dilemma. You could think of tube amps that do bass well with multi-drivers, but we're talking about ridiculous money.

Many tube amps do have soft bottom ends and lack driver control. Some because the tubes themselves aren't liner into the lower ranges and some of it is choice of transformers used.

Not all are like that.

Some of the best low end and driver control I have heard was from some of Gary Dodd's tube amps, and they are not high at all. Even his 8 watt amp had really good bass response and driver control.

[Andrikos]

Danny,
Good info as always.
Thanks and I'll looking into this some more.

Btw, where the heck are the Neo 10's?
It's taking quite a while for them to show up isn't it?
Any problems?