New Build- Fisher 500-S Iron

[SilverFox]

I've been away for years now. Okay, Someone gave me a Fischer 500-S stereo receiver that is in great shape. However, it is missing tubes and the strings that connect the tuning capacitors are broken, as well the AM ferrite antenna. The guts look fantastic as does the Iron. So, I figured I would build a stereo amp out of it. I know, ebay says the sale value is, $2000. Not really. The vintage HiFi market just ain't there anymore.

Here is a link to the schematic: https://www.fisherconsoles.com/non%20co ... 9%20sm.pdf


Now, I've started some research to determine what potential tubes would work with this amp. And, I've run the design question through AI to come up with potential output tubes that will match with the Iron in question. The phase inverter would likely be based on a Marshal 40 watt power amp section. I would like to use either 6L6 or EL34 tubes but they won't work well with these output transformers. I had thought the EL84 would be a good candidate, but they are not designed for this work load. The EM84 would work, however like the original 7189 tubes they are quite expensive. As well, I have the other tubes desired already. If there is interest, I can post the AI research, it's short, and reached the same information, as well, several of the same sites I used are included as references' in the AI output.

In the past, I built a stereo power amp based on the Sunn Sceptre amp. I still use it with my Fractal Audio AX8, into a 2-12 cabinet with Sheffield Speakers. Sounds absolutely fantastic.

Thank you for any assistance the forum may be in this project.

Best regards,

Silverfox.

[nuke]

EL84 should be just fine with these transformers and voltages. Just use decent ones they should be fine.

Have you measured the transformers to determine the wind ratios?

Or maybe play around with 6GK6, which just has a different pin out.

[SilverFox]

Thanks. For some reason I didn't get notification of your post. Anyway, I've been deep diving on this project. I may just use EL34's and reflect a lower impedance back to the primary. Looking at a Dirty Shirley style build. Sounds like a tuned JTM 45, on my modeler anyway. I've read the EL84 can get shrill? Thanks again for the reply.

Silverfox.

[martin manning]

Side note notifications havent worked on this site for years.

[SilverFox]

The direction has changed on the amp build. This thread is no longer relevant. I'll be opening a new Topic for the build. The problem was: I wanted to use 6L6 output tubes but the OT impedance was too high. I could have made the OT's work but there just wasn't sufficient power in the end unless I paralleled the OT's.