JMP with 6550's vs EL34's?

[Gainfreak]

6550's also have a cry to them or a whine that I can't stand and they also have a weird attack.

The only way Ive heard 6550's sound great is when someone tweaks the amp. Every old marhsall that Ive heard that had nothing done to them that had 6550's has sounded bad to me but YMMV.

Do you hear that in my clip I posted? You really need to tweak any amp for different power tubes than what was intended IMO.

When I say tweak Im talking about screwing around with the preamp section/modding the amp from its original state. Every STOCK marshall Ive heard with 6550's has sounded really bad to my ears. I haven't heard the clip though. I'll have to check it out.

 

[Greazygeo]

6550's also have a cry to them or a whine that I can't stand and they also have a weird attack.

The only way Ive heard 6550's sound great is when someone tweaks the amp. Every old marhsall that Ive heard that had nothing done to them that had 6550's has sounded bad to me but YMMV.

Do you hear that in my clip I posted? You really need to tweak any amp for different power tubes than what was intended IMO.

When I say tweak Im talking about screwing around with the preamp section/modding the amp from its original state. Every STOCK marshall Ive heard with 6550's has sounded really bad to my ears. I haven't heard the clip though. I'll have to check it out.

Well mine isnt stock either

 

[SQUAREHEAD]

]You'll make it sound worse.....6550's are great when you get the amp tweaked for them...much bigger and ballsier sounding with 6550's. KT88's are similar in sound but alittle smoother.

You might have heard this in Scott's thread, but here's my modded plexi (similar to a 2203) with 6550's....

http://www.greazyspoon.net/clips/Pl... the tone I'm dreaming of! Keith :thumbsup:

 

[JTyson]

I've heard both that blew my socks off. 6550's seem to be a little more { for lack of a better term } mechanical sounding, but this is what a lot of guys who did heavy stuff liked about them. If you decide to change them, it will give the potential buyer some leverage to get you a little off your price, but any decent amp tech could put it back to spec for 50-65 dollars { or less } plus tubes. If he charges more than that, he's robbing you. It would take less than 30 min. to change 1 resistor and re-bias the amp. We are not talking about some huge mod, its probably the least evasive mod you can do to the amp. The 6550 vs. EL34 debate will go on forever, I think each does lean towards a given tone, each brings somthing the other can't to the table, it just depends on the table you like to eat at - Jim

There is actually alittle more to changing over than one resistor. Its stil not hard though...

Have a JMP,took it to my tech, He changed 1 resistor in the bias supply, put in EL-34's, and re-biased the amp. It will still stop a charging elephant at 100 ft. 17 years later, with no problems. I watched him do it. BTW- that dokken clip sounds awesome

 

[Code001]

I've heard both that blew my socks off. 6550's seem to be a little more { for lack of a better term } mechanical sounding, but this is what a lot of guys who did heavy stuff liked about them. If you decide to change them, it will give the potential buyer some leverage to get you a little off your price, but any decent amp tech could put it back to spec for 50-65 dollars { or less } plus tubes. If he charges more than that, he's robbing you. It would take less than 30 min. to change 1 resistor and re-bias the amp. We are not talking about some huge mod, its probably the least evasive mod you can do to the amp. The 6550 vs. EL34 debate will go on forever, I think each does lean towards a given tone, each brings somthing the other can't to the table, it just depends on the table you like to eat at - Jim

There is actually alittle more to changing over than one resistor. Its stil not hard though...

Have a JMP,took it to my tech, He changed 1 resistor in the bias supply, put in EL-34's, and re-biased the amp. It will still stop a charging elephant at 100 ft. 17 years later, with no problems. I watched him do it. BTW- that dokken clip sounds awesome

The proper way is to change from 6550s to EL34s involves changing 4 resistors. Some people just piggyback a resistor to get in the bias range, but most people agree that swapping all 4 resistors makes it sound better.

Edit: some people move the purple, negative feedback wire around as well.

 

[JTyson]

Are you talking about 4 - 1 at each tube socket, or 4 on the board?

 

[Code001]

Are you talking about 4 - 1 at each tube socket, or 4 on the board?

4 on the board. 6550s to EL34s is the following:

150k to 220k x2
47k to 56k
27k to 15k

Feel free to experiment with the NFB wire as well. Most people like it on the 8 ohm tap.

 

[Greazygeo]

Hey Geoooorge!!
I played Gary's Wiz-MC with the original tubes for a month or so and I was in love with that amp... then after the Sylvania's went in, it was even better! Just when you thought it was already there, Boom!
Now that particular amp is the tone I'm dreaming of!

Keith

Awesome! Killer amps for sure. I bet those tubes do sound good in it. I wish you could hear my Metal. I still prefer it to the MC. But the MC is cool too

 

[Greazygeo]

I've heard both that blew my socks off. 6550's seem to be a little more { for lack of a better term } mechanical sounding, but this is what a lot of guys who did heavy stuff liked about them. If you decide to change them, it will give the potential buyer some leverage to get you a little off your price, but any decent amp tech could put it back to spec for 50-65 dollars { or less } plus tubes. If he charges more than that, he's robbing you. It would take less than 30 min. to change 1 resistor and re-bias the amp. We are not talking about some huge mod, its probably the least evasive mod you can do to the amp. The 6550 vs. EL34 debate will go on forever, I think each does lean towards a given tone, each brings somthing the other can't to the table, it just depends on the table you like to eat at - Jim

There is actually alittle more to changing over than one resistor. Its stil not hard though...

Have a JMP,took it to my tech, He changed 1 resistor in the bias supply, put in EL-34's, and re-biased the amp. It will still stop a charging elephant at 100 ft. 17 years later, with no problems. I watched him do it. BTW- that dokken clip sounds awesome

You should try swapping the two 150k resistors in the bias section to 220K and most likely move the purple wire on the impedance selector as well. I don't remember which one....8 0hm tap I think.

 

[JTyson]

I dug up his number { he's moved since this happened 17 years ago } and asked him, becuse now I'm wondering if he did it properly, and how could it sound so good if it was done improperly ? He said it was 4, not 1, it did only take 30 min., all on the board, just as you said. I stand corrected ! ...........It was 17 years ago!! -thanks- Jim

 

[Capulin Overdrive]

holy shit!


i've been working some hours lately and thought this thread had died!



i'd pretty much figured out what i'm gonna do, but this helps.


been wanting to learn to build, so i'm gonna stick with that route for now. want to do the Egnater class and still might, but guess i'm just gonna jump in with both feet on a Metro and do a stock build and then send it off to somebody like Dave Friedman to get hot rodded.


someday i'd like to have some unbutchered Marshalls around, and suppose nows a good time to buy with the economy shot to hell, but the hot rodded thing is more what i'm after at the moment.

 

[Marshall Law]

this thread did die, till you bumped it 3 days later