Raising the While Flag on 604 Project

[Seadweller]

Hi gang,

Well, as many of you know, I’ve been working on a Great Plains 604 based project for over 2 years now. My progress slowed considerably 6 months ago, and over the last 6-8 weeks, it has stalled completely.

I’ve come to realize that life is just too busy now to finalize this project, so I’m getting ready to raise the white flag. I guess something like this is better done during retirement! I already sold my tube amplifier, so I now have two magnificent loudspeakers sitting quietly in my living room.

I’m embarrassed to admit how much I have invested in them. The cabinets were made by a craftsman that specializes in custom cabinetry for multi-million dollar homes. Most of his handiwork is in excess of $100K. I used a proven cabinet design, with input from a variety of kind and generous individuals. I had actually dreamed of turning this project into a very small, boutique commercial venture, custom building speakers for clients. The cabinet construction was heavily documented with photo’s, and I can obtain the drawings, which were done by hand, yet look like they were generated by a CAD program. The drawings themselves are magnificent, and were done so the system could be mass-produced if desired. I even used commercial parts, such as gold binding posts, polypropylene inserts for the ports, etc.

I have two sets of XO’s, the original Great Plains set, and a custom set that was built by a wonderful gentleman out of Chicago, who lives and breathes these types of drivers. They are built on Plexiglass boards, hand wired and soldered point-to-point. They're magnificent! He is certainly on the brink of a breakthrough with this XO.

I guess I’m looking for some advice on selling the speakers. I realize that is a very special speaker system, so an ad in my local newspaper won’t cut it. I don’t even know how to value them. Of course to me, they’re worth a million!

Any input or advice would be most appreciated!

Thanks!

[Panomaniac]

Photos, lots of photos, please

[valhallax]

all i can say is...see it through. sounds as if your almost there! if you go to any of the boutique shops, your pair will blows theirs away! you can do this. sell them?! no way, hook 'em up and play your favorite music through them

[Seadweller]

all i can say is...see it through. sounds as if your almost there!

Well, the reason I pursued this project to begin with, is because I went down the "high end" path many years ago, and could never find a system that recreated the magic that my Model 19's provided. I went through numerous systems, from Thiel, to Martin Logan, to Magnepan, to Von Schweikert, to......After visiting CES two years ago, I realized that none of the consumer products appealed to me, with the exception of systems like the Edgarhorn, which are hideously expensive.

Anway, I've been fighting with extreme midrange energy and weak bass output through the entire project, and I just don't have time to take measurements, and do what's necessary to finish this out. Right now it's a matter of tweaking the XO's, but I don't know how to do it. The gentleman that has been making the XO's for me has already built 3 pair, which is well beyond any expectations I had.

I've tried Stehpaen's 4th order, the Great Plains stock version, Jeff Markwart's 3rd order, and 3 custom XO's to no avail. While it seems as if I'm close, I'm in the same position I was the day I put the drivers in the cabinets.

I'm a little disillusioned at this point, and the excitement is slowly waning...

[GM]

Anway, I've been fighting with extreme midrange energy and weak bass output through the entire project..........

Hmm, something doesn't 'ring true' as the 'spread' through the XO BW should solve the 'hot' mids, but for sure the larger HF horn that allows a nominally 1 kHz XO I'm a 'broken record' about will solve it. Ditto woofer diaphragm treatment, but this typically requires significant experimentation with the real possibility of ruining some before getting it right.

As for weak bass, these drivers either must have a huge cab tuned to blend as well as practical to the room and/or a very high output impedance source combined with good room boundary loading, so with such an acoustically small cab you apparently don't have the latter and I assume the Fs tuning required.

GM

[Panomaniac]

What I ended up with on the Mantaray orn 604s I have was nominally ~1600Hz, 3rd order crossover with a spread. I'll see if I can find my notes.

I found that the mantaray horn just would not play down lower and stay clean.

[Seadweller]

As for weak bass, these drivers either must have a huge cab tuned to blend as well as practical to the room and/or a very high output impedance source combined with good room boundary loading, so with such an acoustically small cab you apparently don't have the latter and I assume the Fs tuning required.

GM

Thanks GM...You've actually been very gracious with your time and input throughout this project, and I thank you for that. I actually moved to a tube amplifier to experiment with a high output impedance source to no avail. Funny thing is, I even thought my oldie but goodie Rotel CD player might be contributing to the excessive midrange and/or weak bass, but have yet to try another CD player to see if that might be the case.

The system is extremely shouty in the vocal range; so much so that listener fatigue is nearly immediate, making them unlistenable. I can only describe it as a "megaphone" effect in the frequency range where vocals appear. Any instrument in that frequency range is significantly "enhanced." It overwhelms the rest of the spectrum, and at times, is painful to listen to. It almost sounds like a giant clock radio, I'm sorry to say.

Other's that have listened to the system notice it immediately. It almost seems as if woofer beaming is the issue, and despite the inclusion of a notch filter in this range on my lastest round of XO's, the beaming persists.

Believe me, I hate to give up on this project, but I'm stuck, and my wife has been very nice about FedEx shipments, XO's lying on the floor, and a washer/dryer combination sitting in the living room! 8)

[sba2]

....Right now it's a matter of tweaking the XO's, but I don't know how to do it. The gentleman that has been making the XO's for me has already built 3 pair, which is well beyond any expectations I had. I've tried Stehpaen's 4th order, the Great Plains stock version, Jeff Markwart's 3rd order, and 3 custom XO's to no avail...

....Is it possible to install an L-Pad in a crossover...

Wait !!! You've gone through six different crossovers? Hmm ! The gentleman from Chicago should have suggested L-pads for his second build. This would have given you some control of the slope and the balance (similar to the model 19 crossover).

[gortnipper]

Seadweller - have you tried removing the 3 ohm resistor on the bass circuit? Or replacing it with a different value one? I know the MLTL design for these drivers call for it, but if the bass is anaemic in your room, maybe this might help tune to your bright room?

David

[Seadweller]

Wait !!! You've gone through six different crossovers? Hmm ! The gentleman from Chicago should have suggested L-pads for his second build. This would have given you some control of the slope and the balance (similar to the model 19 crossover).

There have been L-Pads in all the XO's he's built, but it's a struggle to control the horn energy without killing the highs...

Perhaps some experimentation with the range that the L-Pad covers would help?