Nice Fisher console stereo

[electra225]

This one is interesting to me. Referring to the diagram, the chassis uses 6HU8 output tubes. I'm not familiar with those, but it shows "P-P output". Perhaps some of the Fisher gurus will chime in and straighten me out.

https://www.ebay.com/itm/204208729357?h ... R8zA3NW3YQ

[Firedome]

Weird... looks like a typical Ambassador or Custom Electra faceplate, (usually 6bq5 pp) but those tubes are pentode-triodes often seen in RCA CTC color sets, I have spares for my CTC11... no idea Fisher had ever used these in a SE application like this, just plain weird. Learn something new every day! Looks like an AT-6 in there too.

[Hi-Fi-Mogul]

The Fisher site has the owner's manual
and it gives the chassis number of 290-T.

This cabinet is D-39-IP (Italian Provincial/Distressed Walnut).

Pretty cool, add MPX for $20.00.

And they did put in a Garrard AT-6 changer.

https://www.fisherconsoles.com/diplomat%20II.html

[TC Chris]

The 6HU8 is a twin pentode tube--both halves of th P-P output in one tube:

https://frank.pocnet.net/sheets/201/6/6HU8.pdf

But note that the specs say 3 watts output, 10% harmonic distortion. That's a flea-powered amp by component standards, and not too clean. Fisher mst have been coasting on their name on this one.

Chris Campbell

[SeniorSteve]

I looked at the tube specs and 3 watts is for a single ended output. For push pull it jumps to a little over 9 watts at 5% distortion. The tubes are quite expensive, but look at the bright side, you only need one per channel! They were used extensively in german branded consoles (I had a Grundig). It had a dead output tube in the Grundig I had, and replaced the 2 6HU8 tubes with 4 EL95 tubes. I think the 4 EL95 tubes were still less than half of what one 6HU8 (ELL80) was. Made a bracket to put the 4 tubes on it. Not the cleanest, but it worked very well, and electrically the EL95 tube is the equivalent of one half of the 6HU8. Gave that console away, it was from 1963.

4 tube setup.jpg (55.85 KiB) Viewed 7871 times

[Motorola minion]

Fisher was transitioning to the solid state output models (W-59 A-69)* but decided to offer the lower-priced Diplomat with the two 6HU8 as the audio outputs.

*Warwick was a near equal to the all-tube Electra VII for 1964, but W-59, A-69 and other models used a 6HU8 to drive an interstage transformer at high impedance to feed a low impedance input of push-pull transistors.

[Firedome]

I need new reading glasses, I read or interpreted it somehow ? as 6GH8, which as a triode/pentode, which would make no sense here as I said. I was thinking the triode section SE for output and the sharp-cutoff pentode section... for ? I knew it was used in my TVs.
The 6UH8 is like a smaller version of the 6DY7s Stromberg used in their unique ASP-422 stereo amp(pic), those tubes are very expensive.

[walyfd]

I'm sure Avery knew what he was doing when this came out in the early tube/SS transition years. No way was output or quality going to suffer during this period.

[TC Chris]

Note the difference between size of the S-C output transformers and the Fisher. 'Nuf said.

Chris Campbell