So I have a 50W amp fixed bias 2x EL34, around 460V on the plates into a 16Ohms cab. OT Primary is 3K5.
I installed a pair of TAD 6L6WGC in the amp, re biased and got a nice sound. Not too different from the =C= EL34s I had in there, except for a tighter, more focused sound.
Then I doubled the primary Z by switching the amp to 8 Ohms while staying connected to the 16 Ohms cab. The sound changed quite a bit... The amp is darker and the I'm getting a noticeable increase in overdrive. It sounds quite nice.
I just want to make sure I have the mismatch method correctly... What do you guys think?
EL34 to 6L6?
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Stevem
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Re: EL34 to 6L6?
Your ok!
Your new impedance load is some 1K too high for two of those so that would explane the darker sound, and since running the tubes this way will chop 1/3 of the output wattage off, that would explane the added distortion.
Also running the tubes this way into a higher load will make them live longer.
You may want to screw around with the drive signal output level from the PI at this point, as that need changes when you up the load on the outputs.
A easy quick way to see if more signal fits your sonic needs better would be to disconnect the feedback if your amp has such, or add some more resistance .
Your new impedance load is some 1K too high for two of those so that would explane the darker sound, and since running the tubes this way will chop 1/3 of the output wattage off, that would explane the added distortion.
Also running the tubes this way into a higher load will make them live longer.
You may want to screw around with the drive signal output level from the PI at this point, as that need changes when you up the load on the outputs.
A easy quick way to see if more signal fits your sonic needs better would be to disconnect the feedback if your amp has such, or add some more resistance .
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
I don't understand?
I don't understand how changing the output transformer tap to a lower load value and keeping the load the same improves the sound. I'm not criticizing, just questing how this works to advantage.
Another question: If you were to decrease the load to 8 Ohms and keep the 16 Ohm tap live, would that damage the output transformer?
silverfox.
Another question: If you were to decrease the load to 8 Ohms and keep the 16 Ohm tap live, would that damage the output transformer?
silverfox.
-
Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: EL34 to 6L6?
I do not understand your question, I did not state anything about the changes improving the sound, as that is dependant on your ears!
Messing with different loads on different taps can make for too much current being applyed and making for shorted out windings, but in the way you stated of running the OT the higher load does not let the output tubes make there intended current output for the power supply you have in use.
A sure way to kill any OT is to have it working into a open load, or too high of a resistance.
In this case a OT acts like a automotive spark coil, and since the audio voltage swing rides on top of the B+ voltage there is a big voltage arc that has no place to but to punch thru the winding insulation to find a way to ground itself out.
It's a very good safty tip to place a 250 ohm 10 watt resistor across the OTs highest impedance tap a ground just in case of this open circuit issue!
Messing with different loads on different taps can make for too much current being applyed and making for shorted out windings, but in the way you stated of running the OT the higher load does not let the output tubes make there intended current output for the power supply you have in use.
A sure way to kill any OT is to have it working into a open load, or too high of a resistance.
In this case a OT acts like a automotive spark coil, and since the audio voltage swing rides on top of the B+ voltage there is a big voltage arc that has no place to but to punch thru the winding insulation to find a way to ground itself out.
It's a very good safty tip to place a 250 ohm 10 watt resistor across the OTs highest impedance tap a ground just in case of this open circuit issue!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!