TWL's music literally takes wings!
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?
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Twl, I am thinking of building a simple open Baffle design. Speaker would be a 15" coaxial. Bass would start rolling of around 64hz or so i think. Thinking about adding wings like you did on your pipes. I am kind of shooting in the dark here but wondering if they would add much bass. Would appreciate your thoughts. I am striving for the Lowther like sound with added dynamics and the ability to play loud. Thanks in advance for any help you can provide. |
TWL, I found your article extremely interesting because I've been reading great deal about back-loaded horn single driver speakers both DIY's and commercial. I've been an amateur since 1985, but I've never read about the Voigt pipes. What are they? I've been trying to decide what driver and enclosure to use, and you mentioned Fostex, which is one that I'm considering. Which Fostex driver and enclosure did you use? Good and bad characteristics? I am also considering Lowther and REPS R-1. Right now I am listening to 20" x 70" ELS's which I had custom made by JUSTREALMUSIC. They have all of the fine qualities of ELS, but in my listening space they tend to dominate--it's hard to forget they are there. That's why I'm considering the single driver speakers. Should I start at the beginning with Fostex or start at the top with Lowther? Or stay with the ELS? What are your ideas here? Thanks so much. Joe McQuade jrmq@verizon.net |
Here's a couple of articles that might helpTWL Mod Lowther Voight Pipe. Here's another article Voigt Pipe. Lately TWL has been a hard man to catch!LOL |
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