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Lowther Voigt Pipes are up and running

First, the Lowther people sent me a pair of EX3's instead of DX3's. The mistake turned out to be a great match for my Voigt Pipes! For some reason, I did not have any severe comb-filtering problems with this cabinet. But, I did have Baffle Step drop-off that was weakening the bass response and lower midrange. The 12" baffle was losing wave reinforcement at about 360Hz. So I experimented with adding some 12" styrofoam "boards" on both sides of the Pipes. Huge difference! Once I verified the baffle reinforcement that I had calculated, I then bought 12" wide oak panels the full 6' height of the speakers and added them to both sides of the pipes with piano hinges, so I could tune the "wings" by moving them back on various angles to keep the bass, and get them out of the diffraction plane as much as possible. It works great! It turns out that a few degrees backward angle on each "wing" does exactly what I wanted. The imaging stays tight and the bass is really powerful. Baffle step is compensated down to about 125Hz and the port picks up well from there down. the "wings" also provide a 3db boost of the port output so I think I am getting below 40Hz. I've heard people say these Lowther Voigt Pipes don't have much bass. With these baffle "wings" they have killer bass that is tight and deep and powerful. No noticeable holes or dips even when listening to "walking bass". I am extremely happy with the results of this project. I think that this is the key to the Voigt Pipe dilemma. I also added the parallel non-inductive resistors of 24 ohms across the terminals to reduce the impedance spike at the resonant frequency. This lowers the effective bottom end, and I think it helped to wipe out the comb-filter effects too. Comb filtering is the result of impedance/phase changes in the drivers and the pipes at odd-order harmonic points in the bass/midbass. They combine at these points to create nulls or dips at these freq's. I think that the parallel resistors reduced these impedance dips in the drivers, and hence the pipes. A smoothing effect. Seems to work, anyway. Of course, the Lowther drivers are super, super great sounding. You just can't believe how much I am shaking this 24 foot room with one watt out of my MicroZotl! I think overall, I increased the in-cabinet efficiency of the system by 3db with this "wing" mod. That would put this system at 103db with one watt input. It seems to be quite flat in response curve by listening, with some expected room modes reinforcing the bass a little bit. No noticeable "shelving" of certain freq. ranges. Great high end extension, extremely natural tone quality, dynamics to die for, and detail very much like e-stats. Solid images and good, deep, wide soundstage. I am grinning from ear to ear! I've been playing records 11 hours today. This is absolutely too much fun! I can finally get full orchestra sound without the compression that I had on my fostex system. Wait until these Lowthers get broken-in! They are already fantastic! The new Lowther mods definitely work to remove the "shout" that the older models had. No irritating "shout" in the midrange at all. I highly recommend this project to anyone. This is one killer speaker set-up! Questions or comments?
twl
twl OP
3,251 posts
 
Ultrakaz, I used Mar-Hyde rubberized auto undercoat that remains flexible, on the outsides of the MDF sections of the pipes. The lower part of the insides were partially lined with self-stick felt from the crafts section in Wal Mart. As far as resonances in the wings are concerned, I am not noticing any problems there, but I will make a simple bracket arrangement to allow full adjustability as well as locking them in the fully folded position. I don't think any damping on them will be necessary. But when you only have a 1 watt amp, it sure is nice to have to think about getting loud enough to have resonance problems! They do get quite loud. And I'm not really pushing them too hard during the break-in process. After about 30 hours or so, I'll really start to open the throttle on that 1 watt amp. :-) If I played this system for someone, they would never believe that it's only 1 watt. Of course, it is a Berning pure class A triode ZOTL with NOS tubes. And fed by a hotrodded MFA preamp, which is in turn fed by a Teres turntable with OL Silver 250/DenonDL103 thru a Cotter MC transformer. So we're giving these speakers something pretty good to work with. And they do show it. I have to say that this Berning MicroZOTL is a very special little amp that really delivers the goods. Those OTL triodes are hooked directly to the Lowthers and exhibit excellent control and crystal transparency, liquid midrange and full frequency extension from top to bottom with no "tubby triode" sound or transformer saturation rolloff. It kicks butt!
theaudiotweak
2,807 posts
 
I have had cancellation problems with my Dunlavy SC4's. I cured this problem with a crazy looking angled baffle that extends from the top of my speaker to the ceiling. This baffle has about 8 degrees of tilt and hinged angles on the sides. Seems to allow better low frequency loading of the upper and lower woofers, and now, has quite a hit. Everything seems to be more immediate and with better focus. I have tried this device with several speakers including a few Thiel models . I and others felt it was a beneficial improvement. This maybe something as well, you could try. Tom
twl OP
3,251 posts
 
Thanks, Tom, it sounds like you have a D'Appolito driver arrangement and you are loading the top woofer off of the ceiling. This can balance the top and bottom woofers because the bottom one has floor loading. In my situation, I have a vaulted ceiling that is 12' high above my speakers and soars to 16' high at the middle of the room. I couldn't put such an extension on my speakers. Thanks for the tip, though, and others reading this may benfit from your experience.
twl OP
3,251 posts
 
Just for an update, the pipes are breaking-in very nicely. Getting even smoother, and more dynamic. The ability to play louder and cleaner than my last speakers has led me to want to push my little amp past its limits, because I just want more and more! So I am getting a new Berning(See my new thread on the Amplifier Page). VERY special amplifier! I guess that, even with DIY, I am no longer in the low-cost system category anymore. Now rapidly approaching $10k. Is there any end to this madness?
twl OP
3,251 posts
 
The latest update is that I have removed the 24 ohm parallel resistor from the system. It seemed to be making the highs a little too hot. The bass didn't change any, so I think it wasn't needed with the Lowthers. The wings are great though. I love the adjustable nature of them. You can tune them to the record if you want. Just move the wings a little back if you want to reduce the bass reinforcement, or a little forward if you want to kick it up a little. Most times I leave them angled back about 20 to 30 degrees. It is sort of like VTA adjustment. You can adjust if the situation dictates. I like that. Drivers are getting even better with mor break-in. They even play a little louder now, too.
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