EL34 or 6550 in Friedman JMP

  • Thread starter Thread starter glip22
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glip22

glip22

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I know this has been covered but I am looking for more specifics on how well each tube works with Dave's mods. I have a 79 JMP 100 with 6550's now. Amp has BE,HBE,JBE,Modern,Fat,and Sat. It's a piece of cake to convert it. I would only piggyback the 47K resistor in the bias circuit to be able to bias up EL34. I don't think there is any reason to change the 150k grid leaks to 220k. I am looking to use the Groove Tube E34ls. Can anyone chime in who has tried both. EL34 FTW is not what I am looking for More specifics. Thanks Fellows :thumbsup:
 
glip22":bsnryuuf said:
I know this has been covered but I am looking for more specifics on how well each tube works with Dave's mods. I have a 79 JMP 100 with 6550's now. Amp has BE,HBE,JBE,Modern,Fat,and Sat. It's a piece of cake to convert it. I would only piggyback the 47K resistor in the bias circuit to be able to bias up EL34. I don't think there is any reason to change the 150k grid leaks to 220k. I am looking to use the Groove Tube E34ls. Can anyone chime in who has tried both. EL34 FTW is not what I am looking for More specifics. Thanks Fellows :thumbsup:
Click to expand...
Dave could probably answer this question best.
 
Lp Freak":2tsggvk3 said:
glip22":2tsggvk3 said:
I know this has been covered but I am looking for more specifics on how well each tube works with Dave's mods. I have a 79 JMP 100 with 6550's now. Amp has BE,HBE,JBE,Modern,Fat,and Sat. It's a piece of cake to convert it. I would only piggyback the 47K resistor in the bias circuit to be able to bias up EL34. I don't think there is any reason to change the 150k grid leaks to 220k. I am looking to use the Groove Tube E34ls. Can anyone chime in who has tried both. EL34 FTW is not what I am looking for More specifics. Thanks Fellows :thumbsup:
Click to expand...
Dave could probably answer this question best.
Click to expand...
What do you prefer Bro?
 
psychodave":1gef4vtf said:
I would have to think the EL34's (E34L's) would sound better for the mid-range grind Marshall is known for... Sure there are a lot of people who like the 6550's, but to me, EL34's define the sound. Try it out for yourself... ;) The question is... was the amp modded for tone with 6550's being used or EL34's?
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Thanks Dave, That is what I would like to know. Are Dave's mods consistent regardless of tube type? My guess is yes. It was originally modded with 6550's. You played this amp I believe. It was Joe L's. We met up in New Hope and did a trade deal. Good Dude. We wound up talking for about 45 minutes. I am going to try it out by this weekend. Unfortunately I have no EL34's left. The one quad I had, redplated before but I figured I would try them in the amp anyway. I piggybacked the resistor, biased them up no problem and played for maybe two minutes when a pair of the tubes were about to explode. Sounded great, but I am not sure because of the tubes. Glad I was watching. Shut it down in time and went back to the 6550's. I have another quad coming tomorrow. Hopefully they are stable in the circuit. One thing I see is Dave utilizes the NFB wire as part of the JBE mod. That mod sure sounds nice. Don't have to worry about switching the wire to the 4 ohm tap for El34.
 
glip22":r1h8jjzg said:
Lp Freak":r1h8jjzg said:
glip22":r1h8jjzg said:
I know this has been covered but I am looking for more specifics on how well each tube works with Dave's mods. I have a 79 JMP 100 with 6550's now. Amp has BE,HBE,JBE,Modern,Fat,and Sat. It's a piece of cake to convert it. I would only piggyback the 47K resistor in the bias circuit to be able to bias up EL34. I don't think there is any reason to change the 150k grid leaks to 220k. I am looking to use the Groove Tube E34ls. Can anyone chime in who has tried both. EL34 FTW is not what I am looking for More specifics. Thanks Fellows :thumbsup:
Click to expand...
Dave could probably answer this question best.
Click to expand...
What do you prefer Bro?
Click to expand...
Never played one with 6550's but I would guess EL34's.
 
I tried the E34L's out. In my amp I preferred the 6550's. Cleaner, punchier, and a much sweeter bottom and top end. Not as lush in the mids as the EL34 though. A little harder of a tube, but me likes.
 
Like it was said before, you amp was voiced having 6550's already in it so I'm not surprised they sound better. If it's not broke, don't fix it. :thumbsup:
 
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