History on ohm A's and F's.

07-22-09: Mapman
Dale, thanks so much for your (one of the most I have seen) detailed accounting of how the Walsh driver works.

I've always considered the Walsh driver a truly a unique and vastly under-appreciated piece of engineering work IMHO despite my limited understanding of the physics and engineering behind it.

I'm glad there are people like you, Strohbeen and the others out there devoted to keeping it alive and moving forward to the benefit of music lovers everywhere!

Dittos

Dale,
I have enjoyed following your progress over the last couple of years with your walsh refinements. First, do you have any working versions of the "A" type? I only see finished F's on your site. Also, I have to disagree with you concerning doppler effect. You mentioned earlier that there are several modes in operation simultaneously with this kind of driver. I have noted that the pistonic action causes the entire driver to move at lower frequencies which may cause the other frequencies to be affected. When I had my F's and they were driven reasonably loud I noticed this, first with a playback of reggae music. (BMW live disc). When "family man" hit those low notes, the whole driver would shake and cause Bob Marley to sound like he was gargling. No, the amps (2 bridged Dyna ST-400's) were not anywhere near clipping (less than 100W peak transients) when I noted this effect. If this is not doppler effect, then I would like to understand what it is. Best Regards.

Hello Spikedart,

Yes, we do have some re-manufactured A's and the new TLS-II series as well. The A set is available for $13.5K and the new TLS-II's are by order only starting at $16.5K

Unfortunately, I do not have a lot of time right now, but I suspect that the sloppy movement you may have encountered was due to the very soft almost silken spiders and poor support the original F's suffered from rather profusely.

It surprises me sometimes just how the old units played, since most of the time they were hanging half way out of the magnetic gap and flopped around like a flag in the breeze.

Our new units are not like that at all. Still they retain +/- 1/2 inch of X-Max travel when needed.

At some point I will address the movement of a piston driver both compressing and rarefying air in its movement and producing a positive or negative wave front at far less than the speed of sound. In comparison, the Walsh style driver is around 5.5 times the speed of sound

Until the next time...
Good listening to all.
Dale

Spiked,

IIRC, the doppler effect is the pitch shift that results when a sound source moves toward (or away) from you (at relatively low speed). A train whistle is the usual example. If a speaker's driver produced this problem, I'd think that you would get a slight "quiver" around a vocalist's pitch. Given the short distance (and oscillating path) that a driver travels, it would be barely audible at worst.

I wonder why you are ascribing the "gargling" vocal problem you heard specifically to this? There are surely other possible wayward behaviors that would cause what you heard - a flaw in the surround comes to mind. I'm not sure that this is ever audible in loudspeakers, even if the drivers are pointed at you and "qualify" for doppler shift. However, since the Walsh driver moves vertically, it would seem even less applicable. The horizontal "travel" on a Walsh driver is virtually nil. What's your thinking on this one?

Marty

Sure sounds like IM distortion to me!