Publisher Profile

2009 Lone Star Audio Fest: Part 2

By: |

John Busch is more the DIY hobbyist than the full time manufacturer. He drove from California to spread the gospel of the open baffle/dipole speaker. Last year I heard what John can do with careful crossover tweaking when I heard his Altec Duplex dipole arrangement sounded sweet, laid back and forgiving; it’s not at all like the Altec sound I usually hear. This year he brought the Manzanita dipole, using a 15” driver and soft dome tweeter. Regardless of amp power, the dipoles sound like they respond easier than any other design, short of horns. That’s not to say that they don’t like power. After going from flea power to several hundred watts, the dipoles came to life. It takes a while to understand the sound of a dipole, so I don’t have too many impressions. It did play with good speed, powerful dynamics and very tonal bass. The bass of a dipole, whether it’s coming from a ribbon, planar magnetic, ESL or dynamic drivers, always seems to be tonal, low in distortion and better connected to the midrange when compared to boxes. On the other hand, dipoles roll off rather quickly, something that can’t be overcome until you go the route of infinite baffle (woofers in the floors or walls). I’d guesstimate that it was rolling off under 35 to 40 Hz.

This system was a headbanger’s dream, although it can play soft and sweet. My Led Zeppelin and Pat Metheny disks have plenty of great guitar work. There’s something inherently right about listening to guitar on a dynamic dipole. After all, most guitar amps are pretty much a dipole speaker with a box to house the electronics. There was one issue and that was a little rise in the presence range, something that I haven’t heard with John’s other designs. He told me that it was due to this particular driver combination. With tubes and vinyl, and the right cables, it wouldn’t be an issue. He said he’s sold some of these in a nice cabinet for $1,500 and in the utility grade cabinet for $1,000. He spends more time tweaking the crossover than working on the cabinet. John is a little like me in that if it sounds good, it doesn’t matter if it’s homely.

I don’t have an email address for John, but will pass it on when I do.

www.johnbuschshouldhaveawebsite.com

Bob Brines, of Brines Acoustics, had a room full of speakers, featuring drivers from Fostex and Lowther. I didn’t get to ask questions as there were quite a few people enjoying the sound, and Bob was quite busy. The model I was hearing was the LT-2000 MLTL with the Lowther DX3 driver. I must say that I prefer the Fostex drivers which seem to have a smoother response. On the other hand, the Lowther is very efficient and detail is its forte. Cabinet build quality is fantastic: these are heavy, solid and resonance free. If the speakers in the Audio Note room are slightly laid back, these are their opposite, with intense, detailed sound. If you are a detail freak, and you are looking for a DHSET friendly product, these should be heard. Further, they work well with small rooms. Bob was using a Creative SB USB external sound card. The amp was a custom built Abraxas Audio 6BX7 PP.

There is no specific price on speakers since they are all custom built for each customer. Bob can supply the parts from Parts Express, or you can request any other audiophile part that is available for the difference in price. Likewise, you pick which veneer you want, and if it is more expensive than the usual veneers, you pay the difference. For the build quality, the prices I have seen on specific pairs of speakers are a bargain. Bob will also do custom work.

I emailed Bob about the Fostex VS Lowther thing. His response was interesting:

“I’m sorry we missed each other, as I had several very good, but very different, speakers. My premier speaker was the LT-2000 MLTL with the Lowther DX3 driver. Very airy and detailed. The second speaker was the FT-1600 MLTL with the Fostex FE167E driver. The drivers had the full EnABLe process applied by Dave Dlogos (Planet-10). The speaker is very smooth and well behaved. It is interesting to note that opinions were split almost 50-50 as to which of these two speakers was the better.”

….which is why there are a lot of choices out there, and Bob can do a bit of tailoring to help you find your sound. Everyone has a different opinion about what is the best; about what is the truth. Either we’re all right, or we’re all wrong. Either way, there’s no point in trying to pick sides (though I still prefer the Fostex).

http://geocities.com/rbrines1/Products.html

The first of two technically oriented rooms, the PR Audio room (see below for the other) offers several very handy services for users of classic or orphaned speakers. The “P” and “R” is Paul Roth, owner/craftsman/electrical engineer. Paul spent 19 years as designer, then senior design engineer at Credence Speakers.

Suppose you have a blown woofer from a company that is out of business. Suppose that there is no replacement. Paul can take said woofer, repair it with products similar to those originally used and you are back in business. Suppose it can’t be repaired. He can take another of your woofers (if you had more than one to start with), test it, and find a driver with similar performance characteristics. Let’s suppose you like your woofers, but they seem to “poop out” too soon. You like the sound, but they can’t handle the power you are putting into them. Paul can test the speaker and look for an upgrade that will have similar T&S parameters, while handling more power.

One thing that Paul stresses (something about which I can say “amen”) is that he uses shims to center the driver before replacing a surround. Most shops simply pass a current through the coil and this supposedly centers the speaker. Unfortunately, that’s not always the result. The spider and the voice coil lead wires will push the voice coil off center. If you don’t center it properly, the voice coil might rub and you will definitely get higher distortion. This very thing happened to me on some drivers rebuilt locally in Dallas. I had six woofers from a pair of Entec SW1 servo subs repaired and something wasn’t right. I heard what sounded like a “chuff”. Sure enough, there was a voice coil rubbing.

I emailed Paul about this and he offered this more technical explanation:

“I’d say that’s pretty good / accurate, except the part about what causes miscentering of voice coils in “refoam” jobs. It’s usually not the forces in the spider itself that causes the miscenterings: It’s the inability of the spider by itself (or assisted only by weak forces generated by the current some people like to run through the driver for “centering”) to keep the coil from “tilting” a bit, that causes the problems. For example, let’s say the cone was not perfectly level, originally (extremely common), and one glues in a new surround, which (if the new roll is unwarped, concentric, etc.,) would tend to level the cone. That might sound desirable, but, in “levelling” the cone, the coil, presumably aligned nicely when the manufacturer glued everything together, would now be tilted slightly. Conversely, a “level” cone can easily be pushed out of level in the re-surrounding process, overwhelming the weak ability of the spider + “current” to resist the tilt. If the cone alignment changes, the coil’s alignment will change with it. It can take only a couple thousandths of an inch of coil tilt to reduce the amount of “clean” excursion available, significantly, when the driver is being “pushed” briskly. This of course does not cover the problems that may occur if the voice coil height in the gap is not “held” correctly, when the new roll is installed.”

Paul can also upgrade (tweak) drivers and complete speaker systems. There are any numbers of Altec and JBL systems that I passed up over the years that could’ve used a lot of Paul’s TLC. He sells tweaked and matched drivers, accessories, car audio speakers and Sundown Audio amps. The driver matching is especially critical for good imaging. He offers comprehensive speaker system and driver testing, a driver design and consulting service and has 35 years experience. I was suitably impressed. If the opportunity presents itself, I’ll hook up with Paul on a classic speaker, tweak it to death and offer a review.

http://praudio.com/site/
http://praudio.com/site/woofer-and-bass-mid-re-foaming-done-correctly/

The next technical room was Smith & Larson Audio, makers of test equipment for speaker and woofer measurements (and much more). Unfortunately, I missed the presentation Keith Larson and Brian Smith made. I didn’t get to ask technical questions or see the tests in progress. When I went in the room, Keith’s Mother, Ruth, and his wife, Ursula, were holding down the fort. They were beautiful and charming people.

Keith brought his personal audio equipment as a demonstration system to show how the test software is used. The speakers were a cool looking line source with subwoofer. The sound was smooth, low distortion and cohesive. Perhaps I can get the Woofer Tester Pro package, and tell Dagogo readers how it can help them get the most out of their system. It offers room analysis, real-time interactive virtual crossover design, gated impulse response, acoustical analysis of the speakers, and more. This is all via your laptop (not supplied) and a small box (supplied) and software. Two Behringer ECM8000 microphones and cables are supplied with the Woofer Tester Pro while only one set is supplied with the lower priced Speaker Tester.

It’s amazing what is available via a small box that connects to your computer, something capable of replacing tens of thousands of dollars of tweaky and touchy test equipment. That kind of equipment needs yearly adjustment to verify accuracy – you will see certification stickers when you go to labs and QC rooms, a mandatory routine if you are ISO certified. Thankfully, this equipment is easily adjusted with supplied precision resistors. These products even allow you to measure distortion, match resistors, test chokes, and much more. I have to ask myself why I don’t have one of these. Anyway, look for some kind of in-depth coverage in the months (or years as the case may be) to come.

http://www.woofertester.com/index.htm

  • (Page 1 of 1)

Leave a Reply

Your email address will not be published. Required fields are marked *

Popups Powered By : XYZScripts.com