OTL Asylum

Posted by rogerh113 (A) on November 03, 2024 at 07:51:43

In Reply to: RE: NYAL OTL 1 Julius futterman repair. posted by pennyford on November 02, 2024 at 17:56:12

I have recently completely rebuilt a Futterman H-3, and have a couple of observations that might be of help.

Apparently the OTL 1 uses printed circuit boards rather than point to point wiring. In some ways that is good, in that it eliminates poor wiring work, but on the other hand will likely require the removal of the PCBs for repair. Not so big a deal, and pretty typical with 'modern' amps.

A capable tube amp tech (used to dealing with high voltage tube systems) could likely tackle the job, but it is likely going to take quite a few hours. A lot, or most of the parts, are quite old and will not likely stand up to any stress, and the audio performance will not be as good as they could be. Possibly just a complete replacement of parts would be more cost effective than troubleshooting a bunch of marginal parts - up to the tech, but a consideration. That would at least give you a bit of a bullet proof amp.

The power transformer in my Futterman had failed, and had to be rewound. If you proceed and need the rewinder name, I can provide that.

It would be useful if you have any documentation for the amp, such as a schematic and the biasing instructions. If you do not have them, they may be posted on the web, or another OTL 1 owner may be willing to send you a copy.

Generally the restoration of an old amp is a labor of love, rather than an economic decision. Sort of like an old collector car. The cost of the amp and then repair is likely to be higher than the final market value, unless you inherited the amp.

Hope that helps a bit. The Futterman amps are not so exotic that they cannot be understood and repaired by someone with documentation, motivation, and tube amp/high voltage skills.

regards -- Roger