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Old 26th February 2009, 08:54 PM   #1
tim614 is offline tim614  United States
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Default Rh84 Ptx

Is this over kill for my RH84?
EDCOR 120v primary, 300-0-300 @200mA, 6.3v @ 4A, 5v @ 3A
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Old 26th February 2009, 09:25 PM   #2
tim614 is offline tim614  United States
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RH84
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Old 26th February 2009, 09:32 PM   #3
Guiness is offline Guiness  United States
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I don't think so.... should work just fine and without getting hot, too....
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Old 26th February 2009, 09:54 PM   #4
tim614 is offline tim614  United States
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thanks Guiness
heat is the reason i wanted to replace the one i have now.
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Old 26th February 2009, 10:11 PM   #5
chrish is offline chrish  Australia
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Depends on price. I guess that the EL84s draw about 40-45mA? The 12AT7 about 5-10?, that would make for about 100mA total. What looks interesting is that the choke is only specified at 50mA for both channels...

If there is a price difference, I would go for a lower spec. 200mA is enough for a stereo PP EL84.
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Old 26th February 2009, 11:21 PM   #6
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I've seen V2 G1 conduction at drive levels far less
than required for the full rated output, squashing
and distorting the drive signal to unrecognizable.

Zob and I had to buffer it with a circuit similar in
concept to Tubelab's Superdrive... That fixed it.

Maybe it was his SV83's, not the normal EL84?
I forget if we tried my RCA 6BQ5's in it or not...
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Old 26th February 2009, 11:21 PM   #7
tim614 is offline tim614  United States
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here are the two EDCOR that am debating on


120v primary, 300-0-300 @200mA, 6.3v @ 4A, 5v @ 3A cost is $57.33 each

Shipping cost is $11.60 via USPS priority mail flat rate.




120v primary, 275-0-275 @ 175mA, 6.3v @ 4A, 5v @ 3A cost is $51.15 each.

right now my amp is drawing 37ma per el84 i dont know about the 12at7 but im guessing 80ma to 100ma altogether.
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Old 26th February 2009, 11:46 PM   #8
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Maybe I was thinking of Zob's 12B4A amp? Forget if we applied
the same fix or different with his RH84? Anyways, stOOpid trick
for abusing a CCS to keep the second coupling cap topped off
with +5VDC, regardless how much A2 might flow.

I think he was running screen voltage pretty low (for SV83),
maybe that was why we were havin to drive G1 so hard???

I can't find our schematics relevant to the RH84, but the drive
buffer mod is almost exactly the same, I'm almost sure, aside
from the usual RH84 Plate to Plate feedback thing goin'on...
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Old 26th February 2009, 11:52 PM   #9
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Quote:
Originally posted by kenpeter
stOOpid trick
for abusing a CCS to keep the second coupling cap topped off
with +5VDC, regardless how much A2 might flow.

OK, what AUDIBLE effect if any does this trick have?
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Old 27th February 2009, 03:02 AM   #10
chrish is offline chrish  Australia
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Quote:
Originally posted by tim614
here are the two EDCOR that am debating on


120v primary, 300-0-300 @200mA, 6.3v @ 4A, 5v @ 3A cost is $57.33 each

Shipping cost is $11.60 via USPS priority mail flat rate.




120v primary, 275-0-275 @ 175mA, 6.3v @ 4A, 5v @ 3A cost is $51.15 each.

right now my amp is drawing 37ma per el84 i dont know about the 12at7 but im guessing 80ma to 100ma altogether.
Damn, I just bought two Hammonds for a pair of monoblocks... Those Edcor prices are good! Get the one with the closest matching voltage spec, the 300-0-300 I think...
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