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Posted: Tue Apr 21, 2009 7:30 am
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FoamStrat wrote:
I put in the 6v6 Blues #2 set from Eurotubes in my HRDx and it totaly rocks. Even the distorted channels are usable now, not garbage crunch. And I am not using any dummy jacks, just rebiased to 50 mV.


that is pretty hot bias point, 30 mV is recommended, 1/2 of the 60 mV which is the bias point for the 6L6s, though I had mine around 45mV and the amp does definitely rock at the higher bias points.


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Posted: Tue Apr 21, 2009 7:35 am
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eladin wrote:
austinrocks wrote:
63supro wrote:
JJ's are great tubes and I also deal with Bob at Eurotubes. I've never had good luck with 6v6 tubes in a 6l6 designed amp. An attenuator would be your best bet. I used JJ's in a Deluxe Reverb I had and they were amazing sounding. A buddy of mine tried them in his HRDlx and the breakup didn't sound that good. The thing to realize is a 20 watt amp is not half as loud as a 40 watt amp. I've been blown off the stage by a cranked Deluxe Reverb just because the amp had more "cut" in the mix.

Just watch you don't red plate the tubes. Good luck. You might really like the way it sounds.


beat me to it, but your right JJs 6v6s handle the plate voltage of a 6L6, and if you put a dummy jack in the external speaker you can run factory bias, the 6v6 wants to see twice the ohmage of a 6L6, the transformer on a hot rod deluxe goes to 4 ohms when the external speaker plug has a jack in it. So its really easy to go back and forth between the 6L6 and 6v6.


Thank you very much. Very interesting. But if I put a dummy jack in the external speaker to run factory bias with 6V6, Will it sound the same that without the dumy jack and the amp rebiased for 6V6? I mean, same tone... Does the impedance afect to the speaker (a 8ohm Celestion)? Thanks.


that is correct you can rebias the amp and get the same thing as putting the dummy plug in the external speaker jack, gets the same tone


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Posted: Tue Apr 21, 2009 1:35 pm
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You need to know the actual plate voltages before you can bias properly. I use a Weber Biasrite. Otherwise the mv numbers mean nothing.
Somewhere around 70% dissipation is recommend.
WHAT YOU WILL NEED TO DO IS:
A) Replace the ground wire on each power tube
socket with a 1-ohm resistor.
B) Read the voltage drop across this resistor
(in millivolts) with your DMM.
C) Read the plate voltage.
D) Use the above readings to calculate the
static dissipation wattage.
E) Adjust the bias to obtain the best tone,
while keeping the tubes within specifications.


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Posted: Tue Apr 21, 2009 2:18 pm
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austinrocks wrote:
eladin wrote:
austinrocks wrote:
63supro wrote:
JJ's are great tubes and I also deal with Bob at Eurotubes. I've never had good luck with 6v6 tubes in a 6l6 designed amp. An attenuator would be your best bet. I used JJ's in a Deluxe Reverb I had and they were amazing sounding. A buddy of mine tried them in his HRDlx and the breakup didn't sound that good. The thing to realize is a 20 watt amp is not half as loud as a 40 watt amp. I've been blown off the stage by a cranked Deluxe Reverb just because the amp had more "cut" in the mix.

Just watch you don't red plate the tubes. Good luck. You might really like the way it sounds.


beat me to it, but your right JJs 6v6s handle the plate voltage of a 6L6, and if you put a dummy jack in the external speaker you can run factory bias, the 6v6 wants to see twice the ohmage of a 6L6, the transformer on a hot rod deluxe goes to 4 ohms when the external speaker plug has a jack in it. So its really easy to go back and forth between the 6L6 and 6v6.


Thank you very much. Very interesting. But if I put a dummy jack in the external speaker to run factory bias with 6V6, Will it sound the same that without the dumy jack and the amp rebiased for 6V6? I mean, same tone... Does the impedance afect to the speaker (a 8ohm Celestion)? Thanks.


that is correct you can rebias the amp and get the same thing as putting the dummy plug in the external speaker jack, gets the same tone


Thanks one more time :)
But if a run the amp with the stock 6L6 in 4 ohm (putting a dummy jack in one input and connecting the stock speaker in the other input) without rebiasing (sth. like 60mv, I suppose), could I damage the amp or the speaker? Thanks.


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