OTL Asylum

Futterman H-3

24.141.114.125

AJ

A

I have waited about 20 years to further modify my H-3 with polypropylene output caps and get rid of the electrolytics. This is the last step in modifying this amp as the couplers resistors and frayed wires were all changed many many years ago.

If I am correct, this will be transformational and I should be getting even more performance from the Futt. I believe it to be a truly great amplifier if used with the correct speakers.

Those that talk of these amps going up in flames etc, never had anything but stellar performance from this piece for decades.

Kemet has finally come out with a cap that is affordable and , beleive it or not, I can make it fit on the chassis with no holes .. stay tuned!

Follow Ups:

RE: Futterman H-3 - rogerh113 08:27:28 03/26/22 (2)
I am very interested in how the caps work for you. I finally got the H-3 project I have been looking for, which requires a complete rebuild, so relevant info for me.
- RE: Futterman H-3 - rhinohifi714 21:59:58 05/17/22 (1)
  these are truly great amplifiers, I finally got around to putting in NOS Olympic/Amperex EL505 I had purchased years back. I had been using the russian variant since I bought the amp, with no problems.
  I just couldn't help but try the Amperex out, very nice.
  
  Edits: 05/17/22
  - RE: Futterman H-3 - Mike Mount 11:01:03 05/23/22 (0)
    That's mighty purty Rhino!!!
    I want to hear one - one day...
RE: Futterman H-3 - AJ 16:48:47 03/25/22 (0)
Yes, Lew the Dc link series

I had purchased some Unlytic surplus caps from ebay over the years however, they would have been a kludge because I could not get the values I needed.

New Unlytic caps in this form factor of 8-900mfd were going to run me about $500 and that was a no go for this amp.

The original H3a(a) used photo flash caps that were evidently not very robust with respect to aging. Bypassing would of been a good idea at the time.

You are correct that more is available now. However, this pandemic has certainly put a lot of items on protracted delivery. Common transistors for example are 6mos out for one of my projects ... so you have to make do.

I am looking forward to the mod. I have a couple of items to clear my bench and I will move forward with it.
- KEMET Film Capacitors (Open in New Window)
RE: Futterman H-3 - Lew 13:28:09 03/25/22 (0)
DC Link? Looks like it, and Kemet makes such capacitors. Great idea. When I owned Futtermans, I also found very positive results by bypassing the output capacitors with high value film capacitors, even though I am not generally a fan of bypassing coupling caps. Nowadays you can find higher value film capacitors at the requisite voltages perhaps easier than 20 years ago.

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