I was planning on making the needed modifications, not just swapping them. They are very similar and the circuit would only need slight alteration. The suggestion to use 6p14p is very good and I have a pile of them sitting here already, I have some strange, romantic relationship with the EL84 and it always seems to be the first thing on my mind when i think tubes, probably 'cause it was the first tube I ever worked with and that wasn't very long ago. Now onto those caps...
EL84
The proper Russian tube to use is the 6p14p-ev ,not the 6p14p.
It is difficult to modify the amp to accept the EL84, because the to high B+ voltage. The max B+ for the EL84 is around or just above 300V. I think this amp can deliver 22W/ch, the EL84 is rated 15W in push-pull.
The proper Russian tube to use is the 6p14p-ev ,not the 6p14p.
It is difficult to modify the amp to accept the EL84, because the to high B+ voltage. The max B+ for the EL84 is around or just above 300V. I think this amp can deliver 22W/ch, the EL84 is rated 15W in push-pull.
Well that's good news, you still have a lot of coupling caps that need to be replaced - every one of the originals you haven't yet done. I know its a pita but those caps leak like sieves in their old age.
Replaced C704, C707,C713, C716.
Listen to it for half a day, the sound is quite different from all the solid state amp that I have.
I have not finish with it yet, the voltage that I have on 6AQ8 pin 1 and 6 and 6BL8 pin 1 and 6 is quite different from the schematic.
Is this normal?
Listen to it for half a day, the sound is quite different from all the solid state amp that I have.
I have not finish with it yet, the voltage that I have on 6AQ8 pin 1 and 6 and 6BL8 pin 1 and 6 is quite different from the schematic.
Is this normal?
Higher, lower? So that we don't have to look up the pin designations can you mention what electrode that is in future posts?
Back in the day analog multi-meters with 1K - 20K per volt input sensitivity were common, and in the case of low current circuits with high value resistors would tend to load the circuit down during measurement. The values listed in the schematic were a reflection of the meter used to make the measurement, and the sensitivity of the meter used should be listed somewhere on your schematic. Today modern meters generally have much higher input impedances and take much less current from the circuit they are measuring, and the readings can be off by a large % relative to the schematic value as a result.
Do some listening today, found hum on one channel.
The hum is from the preamp section, if I swap the 6AQ8 then the hum will go to the other channel.
So one 6AQ8 is causing the hum. I bought 2 of these from the same internet source.
Is there any way to be sure the tube is good and how?
If I will order these tubes again, what are the direct replacement of 6AQ8 I can use?
The hum is from the preamp section, if I swap the 6AQ8 then the hum will go to the other channel.
So one 6AQ8 is causing the hum. I bought 2 of these from the same internet source.
Is there any way to be sure the tube is good and how?
If I will order these tubes again, what are the direct replacement of 6AQ8 I can use?
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More listening for a few days, high and mid is very good, not enough bass.
Is there any way to improve the low?
Is there any way to improve the low?
I got 1 pair ECC85 Tungsol. 1 tube has hum.
Got another pair 6AQ8. 1 tube has hum.
Another pair of ECC85 RFT, works good.
Can any one tell me why the tube hum? Does that means it is no good?
What is the best way to match the 8 Ohm and 16 Ohm output transformer, if I have 4 Ohm and 6 Ohm speakers?
Thank you.
Got another pair 6AQ8. 1 tube has hum.
Another pair of ECC85 RFT, works good.
Can any one tell me why the tube hum? Does that means it is no good?
What is the best way to match the 8 Ohm and 16 Ohm output transformer, if I have 4 Ohm and 6 Ohm speakers?
Thank you.
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Probably the isolation between heater filament and the cathode is not sufficient (there is a current leak from filament). It's not good to use those tubes in schematics where they give a hum. It will not start fire but gives unwanted hum. In some other schematics the tubes may not hum, just give a try.
Probably you could get rid from hum when give heating with DC. Is it worth it..?
I'd use the 6-ohm speakers on 8-ohm output.
Most likely the tubes are OK, but the Sansui only have one filament supply and no wire wound (100 Ohm) balancing potentiometer. Looks like you just have to select the tubes for minimum hum.
Hello, I was wondering if you might know what the two big power resistors that are about 3 inches long, between the power supply and the first OT, that sit on top of the chassis are? A "replaced" one of mine is burned and the other either says 30H 3.6K Ohm, or 30H 8.6 Ohm.
Thanks if anyone can help.
Have you downloaded the schematic from the link in Post#1?
Is this R001 or R002 that you are talking about?
Thanks VictoriaGuy,
I did get the 500a schematic and found R001 and R002. 1K (15) and 3.6k (30).
Now off to try and find 3 inch versions of those!
Thanks again.
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