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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

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Restored end stage of Voice of Music 560A from 60s, added preamp 6SN7 /End tubes - 6BQ5/. All caps inside was bad, I changed to new. Resistors are the sames. Sound is amazing and better old amp. OTs are very good /very good iron/ not big, but cover 40-50 Hz. Bass is deep, increadible....
 

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Restored Zenith, photos before and after. Potentiometers are moved from back to front side. SE 6BQ5.

I like those old amps - lots of character - in my most humble opinion it would be better to replace those 70's looking silver knobs with something else that's a bit more sympathetic with the overall appearance
 
Knobs was in very bad condition and I decided restor the sound, that is amazing. OTs are smal, but cool! There was 3 wholes /someone drilled and tried sumthing, and I decided put potentiometers to make vision better/. I didnt expect this inbelievable sound! OK, I will put suitable more dark knobs, thanks!
 
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Restored end stage of Voice of Music 560A from 60s, added preamp 6SN7 /End tubes - 6BQ5/. All caps inside was bad, I changed to new. Resistors are the sames. Sound is amazing and better old amp. OTs are very good /very good iron/ not big, but cover 40-50 Hz. Bass is deep, increadible....

Hello Azazello,

Hi it possible if you can provide a schematic of the voice of music 560a with the addition you made?

Thank you
 
I didnt find the schem. Old Zenith worked, but channels had different modes. I changed some parts, caps, stage by stage, I replaced cord, switch, potentiometers, wires...and painted. Very big dencity inside. Very hard to rankle again to drow the shcem, sorry. But sounds cool with RIAA and record player.
 
6S4S (6С4С) with EF86 (6Ж32П)

HV stage is with 5C3S (5Ц3С) and two chokes and 4 capacitors (20uF motor run - 10H - 100uF/450V Siemens - 10H - 2x100uF/450V Siemens). The heater of rectifier has 30 seconds delay on. Output valves have DC heating with lm350 with slow start of 7 seconds. All transformers (5) and chokes (2) are DIY.
 

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PP amplifier EL 34, schematic LMO and PCB by alex mm :D Work in progress .Power supply and delay (green PCB)
BR
Alex
 

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This is a EL84 with a 12AU7 driver, deliver clean and nice sound, most from used parts lying around in the garage, mix and match is not always perfect, but a finished project out of the garage is always satisfying.
 

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The sound was excellent on the bench. Now that it's in the box, I have 3 issues:

  • mechanical hum from power-transformer. I tried a DC-blocker, not better. I think it's a bit overloaded with my 230V. Will try to use DC for heater, at least to confirm that a reduced load would help.
  • 50 Hz hum, even with shorted inputs. I'm not sure how to cable the input coax cables in regards to audio ground. Currently only the internal cables red+black are used between PCB and RCA input sockets, I will try to connect the coax shield to the audio ground on the PCB side.
  • intermittent "sound crashes" in the right channel. Need to swap tubes, I guess one is dying.
But to your original question, it sounded nice before casing, now need to fix the above issues and move it to living room on my Magnat speakers.