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Aikido: Width control

J Epstein

2002-02-08 7:24 pm

I implemented a width control for my Aikido preamp today as follows:

I rigged a 3-position, on-off-on switch so that the L & R channels (at the grids of the upper tube in the 2nd stage) were either short circuit, open circuit, or connected via a 23K5 resistance in series. The 3 positions, then, are Mono, Stereo, and Narrow Stereo.

This was John Broskies suggestion in the blog about Aikido enhancements. Works like a charm.

I can't imagine a situation where I would want to hear exaggerated stereo width, but I like to blend to mono often (I prefer to get the cancellation of some of the groove noise on mono records) so I chose these options as the most useful for my implementation.
One could of course replace the 23K5 with a variable resistor, say 50K, for width adjustment control, but life is too short to fiddle with a width adjustment control!

I just tested it using the 1st Beatles record which was actually the impetus for bothering with this idea in the first place, and the result is perfect for me - instead of the vocals hard right and the band hard left, each channel appears to be coming from about halfway between the center and the speaker.

I also put a width control on one of my amps (not an Aikido, but a
small SE power amp that I also use for headphones). I did it like
Broskie suggested, with 20% narrow and 20% wide, though.
The Narrow position is quite a lot more useful. Couldn't live with-
out it, esp. when listening to all those 50s / 60s pop and jazz
records with "crazy" stereo, such as the one you mentioned. It
improves the listening experience immensely.

I'm now building an Aikido, and guess what? It will have a Narrow
switch or maybe even a full-mono to full-stereo pot.

Morgan L