newer than noob looking for advice on RH84

[mctavish]

I have re-built many of those exact Zenith consoles into RH84 and can say they sound great!! Should work out great.

[Eli Duttman]

I agree that a RH84 with the Zenith "iron" should be fine. If the approx. 2 WPC triode wiring yields is acceptable, following the DECWARE SE84 design will work out. If a SE84 knock off is tried, use a current production, Russian, 5AR4 as the rectifier, which will increase the B+ rail voltage. The forward drop in a 5Y3 is quite large.

BTW, watch the phasing of the O/P trafos. Zenith was "cute" and used the 6BQ5s as a mono push/pull amp for a single bass driver. "Cheap Charley" strikes again.

[maxro]

Originally Posted by planet10

The Grundig OPTs we used for our RH84 were closer to 9.6 than to 5k -- close to what the Decware OPTs are. Just means lower distortion and a bit less power.

I don't know about the blanket statement of distortion reduction with increasing impedance. See HERE; it looks like 2nd harmonic distortion goes down and 3rd goes UP steadily as load increases from 4.5k to 5.2k to 7k for an EL84 single ended.

[planet10]

A 10k>8 OPT can also be considered a 5K>4 OPT

dave

[maxro]

True, as Globug already pointed out.

[fatuncle]

Wow Thank you all! I am learning a lot, This looks very promising I think I now need to sit down and reread all of this a few times so it sinks in and then start disassembling the Zenith Chassis. Then I need create a parts list and get some things ordered. I am sure I will be asking for your help again real soon as I actually start the build,