Toilet seat covers and open baffle loudspeakers?!

[Erik Mandaville]

My wife and I were doing basic, household shopping last weekend at Target, and I saw something in the 'hardware and home improvement' that I thought would work perfectly for a temporary open-baffle Lowther installation. A toilet seat cover in natural oak could be perfect! The oval shape with rounded off edges might be perfect for low diffraction, but the seat cover itself would need to be removed from the actual toilet seat. It could then be glued and screwed to a more appropriate piece of wood. Actually, I thought using the seat cover in conjunction with the seat might be useful: It would provide a hinged system that would allow for experimentation of the best driver angle -- which in my case would maybe need to be slightly less than 90 degrees in relation to the floor.

I have a small problem though: My wife said she thought the idea was interesting (that was nice!), but that she was not altogether comfortable with the thought of having a toilet seat on top of each La Scala! How can I help but admit she has a point. It could be just the thing though, so maybe I'll try this minus the actual toilet seat -- which is the most 'telling' about the truth of the form's intended function!

And for Moondog owners: I recently received an e-issue of the Transcendent Sound newsletter, and Rozenblit included a very simple procedure for killing some ground loop noise in one of his OTL amps. He indicated this would only be a concern for those using very high sensitivity speakers, so I thought I would pass it on to you all. My Moondogs are really fairly quiet, but I do get a very low-level hum with an input from my preamp. The modification is this: instead of grounding the ground of the RCA jack directly to the chassis, make the ground connection by way of a 10 ohm (1/2 watt)resistor. The reason this would work well on Moondogs has to do with the proximity of the RCA jack and speaker binding posts. One could simply install the resistor between the negative binding post and RCA jack ground tab. The input jack on my amps, and I think Leok also has this, is on the top of the chassis, so I'll have to try things slightly differently....This may or may not work for you, and if you don't have any noise issues, than it's not even a concern. I just wanted to pass it on as something to try.

Erik

[fini]

I think the tiolet seat would look pretty cool. Unfortunately, I predict it will sound like $h!t.

[Deang]

I have no idea why you would want to integrate a Lowther driver with the Scalas. The whole point of the Lowther is the coherency obtained from using a single driver. Seems like putting it in the mix would result in timing miscues and out of phase wave cancellation problems.

[Erik Mandaville]

I'm sure you all of heard of an MTM (midrange-tweeter-midrange)speaker arrangement...or sometimes called a D'appolito (think I spelled that right)array. There are numerous well-praised systems using this driver arrangment --I've experimented with this before, having built several pair of my own speakers, using drivers from companies like SEAS, Vifa, Polydax (now Audax), Peerless, etc.

With Lowthers on top of the La Scalas, the predicted "...sounds like ****" (I don't blame you for saying that!)simply can't be used to describe the sound. Being intimately familiar with full-range single drivers, I know about their advantages -- as well as some of their disadvantages. I've been using the Lowther PM2As (expensive!)in the rear-loaded Medallion horns for the past five years...and enjoyed every moment....for the most part. Kelly H. made an insightful comment about the importance of a musical foundation, which translates into octaves not usually attainable by Lowthers in horns (at least in the Medallion horns). In the Medallion, their isn't much of anything, really, below about 60Hz. But the midrange is absolutely stunning!

So I had the idea last weekend to remove the PM2As and put them on the front top of the La Scalas. You see, out of the big horns, the Lowthers naturally roll-off at around 150-160 HZ. So, they are being used for their uncanny transparency for mid and higher frequencies -- which is their forte'. Moroever, rear-loaded horns have a compression chamber that submits the rear of the cone to pronounced back-wave reflections, which does nothing good as far as sound goes. Several people I know who use Lowthers in similar horns, use a layer of linear (not concentric) Deflex on the back panel of the compression chamber -- to deal with the back-wave problems and associated distortion.

Being of very similar efficiency (volume level from each seems nearly identically balanced to me), the 15 ohm Lowther is wired in parallel with the La Scalas, but is independent of the latter's crossover. The resulting system is basically an MTM array, with the upper midrange driver (the Lowther) also having the ability for exceptional high frequency response -- which they are more than capable of! But the main advantage, and what I found so fascinating by the sound, was the fact that the Lowther was now functioning very much as a dipole radiator -- much like an electrostatic panel, whose backwave is a fundamental part of its perforamance and sonic signature. There are many open baffle designs, using drivers frequently found in systems using either sealed, vented, or transmission line enclosures; and in terms of Lowthers -- horns.

Deang: Welborne Labs offers the ORIS 150 (approx roll-off frequency of Lowthers in free air), which is very much like what I'm doing, minus of course, the addtional two drivers. Lots of people also use the La Scala bass bin because it is fast enough to keep up with the Lowther -- so much of the forcasted response problems some might attribute to this application, have not been my experience.

I didn't expect anything from this experiment, and had doubts about what it would sound like. But I simply can't forget the incredible sense of immediacy, and our listening room loaded -- fully and completely -- with a sound we haven't heard from either the La Scalas or Lowthers when used alone. Transient response and level of detail was unlike anything I have ever heard. The only thing about the setup was that it was maybe just slightly overbearing in terms of high frequency extension -- which is an easy enough problem to solve. So it needs a little work, but the open baffle Lowther in conjunction with the La Scala was a big surprise. Obviously not everyone might like the sound, but I'm going to do what I can to tweak this thing as best as I can; it's too promising of a sound to not explore a little more.

Lastly, I thought I was the only one who has tried this and liked it. NOT SO! There are a number of internet sites that discuss Lowthers on open baffles. Perhaps the most notable one being Dick Olsher's, who did something very similar in a speaker he calls the 'Basszilla.' Do a search on like 'open-baffle Basszilla' and you can see what it looks like.

To answer your question, Dean: I can't tell you why I decided to try the Lowther on top of the La Scala. If I could share the sound with you, though, you might (or might not) understand why I'm so interested in developing it.

Erik