Thanks!

JD

Jim

Motor run caps are (at least the new ones) metalized polypropylene,
just like the less expensive conventional polypro caps, but I believe
they are oil filled. In any case, they are very smooth, and available
in large values (10-40 uf) for not too much money. If you want
startling detail and smooth, Obligato might be the only somewhat
more expensive route before you succumb to VCaps, Mundorf, . . .

They are big, but that's no big deal in a speaker. I glue in a little
shelf and then use a tie-wrap anchor and tie-wrap. I wouldn't let them
dangle.

Skip

• Hong Kong caps

I also tried surplus Aerovox motor runs in the 8 and 20 uF posiitons of the 1600 Hz crossover and didn't care for the way they 'darkened' the sound and smoothed over detail.

Just for fun, the other night, I priced VH Teflons for my Cornet II board and the total, $900, was 3 times the total parts cost! For a possible incremental improvement? I think not. Perhaps just $100 for .10 by-passes? I remain unconvinced that by-passing has any reward and, in fact, there's a school of thought that says it has a deleterious effect on the electrical function of the main cap.

"A capacitor stores and releases charge over time so that only the ever changing audio signal will pass through it on the way to the outputs, blocking the DC from the tube. Differing values of capacitor charge and discharge in different times. The two different values are said to have different time constants. The small bypass capacitor charges and discharges faster than the larger value cap, thus it affects the higher frequency sounds. The effect of this is the render the highs brighter since they have been stretched over the two different time constants."
-Matthew Anker, SACDMods.com; E.E. student and well-known modifier

I can easily recall the clearly audible improvement in changing the Bottlehead Paramour coupling cap from a ceramic to a Solen Film cap and the Solen, in the Pi attenuation circuit to an Auricap. There was no such change with the Mundorf. Some have said that the Auricap sounds bright and/or brittle. I haven't heard that but I haven't heard sounds above 14kHz for years! The Obbligato oil caps may be smoother on top than the Auricaps and equally 'musical' throughout the audio band. I find them at least equal in the crossover of the Batspeakers, and, in larger values represent a cost savings.

I do know the sound became louder at the same volume setting with this new set up in the crossover. They have been in my Theater 4 pi's for about a year now and are not coming out. I do remember at the beginning I didn't like the motor runs until I added the smaller bypass caps which seemed to quicken things a bit and give me a bit more detail. Was it my imagination? Time for break-in? Who knows, I just liked it better with the auricaps in the crossover. You may have a different take! But I have to say Brothers in Arms (side 2 on vinyl) sounds fantastic over these puppies.

Have fun and experiment.
Frank M