Hello! New to SD forums here. I saw some great posts on here, related to the jcm 602 Marshall. Just picked one of these up and have gone through it discovering that it is an excellent shape. No indication whatsoever of heat on the circuit boards and the discoloration that goes with it. Everything seems to be working really well, but to my ears it's missing some of the Marshall hot sauce. The biggest thing that I found was, is that it came to me with sovtek 5881/6L6wgc' s in it. My questions would be is this an appropriate same pin configuration, to to be in there? would anybody know if there were other modifications typical to using this tube instead of an E L 34? I definitely want to change out the power tubes and get it back to el34 stock again. Can somebody explain to me what to look for as far as modifications go? I want to make this thing Rock like a marshall but is definitely is not doing that now. I know that I will have to rebias. Any help that anybody could give and any warnings that they can give would be much appreciated. I'm fairly tech savvy and understand the dangers of amplifiers. A cap job maybe in the works too. Comments appreciated thank you very much!
Jcm 600 and 5881's
- Thread starter RAC
- Start date
Lake Placid Blues
New member
Re: Jcm 600 and 5881's
By 602 I assume it is a TSL combo and not a JCM600. You should be able to convert a TSL to EL34 if the external jumper from pin 8 to pin 1 is on the tube sockets. This is necessary for EL34s but it doesn't matter to 6L6s either way. You may need to change the bias range resistor to get the bias range right for EL34s. Marshall ran the Sovtek 6L6s during part of the 90s because the supply of reliable EL34s temporarily dried up. Or maybe somebody just put 6L6s in it.
A JCM600 instead of a TSL, on the other hand, might need to run 6L6s to keep the power transformer from getting too hot.
By 602 I assume it is a TSL combo and not a JCM600. You should be able to convert a TSL to EL34 if the external jumper from pin 8 to pin 1 is on the tube sockets. This is necessary for EL34s but it doesn't matter to 6L6s either way. You may need to change the bias range resistor to get the bias range right for EL34s. Marshall ran the Sovtek 6L6s during part of the 90s because the supply of reliable EL34s temporarily dried up. Or maybe somebody just put 6L6s in it.
A JCM600 instead of a TSL, on the other hand, might need to run 6L6s to keep the power transformer from getting too hot.
Re: Jcm 600 and 5881's
Lake: Sorry if I misspoke. this is a marshall jcm 600, 2x12 combo. I thought that was a 602. Made in1998. Marshall labeld preamp tubes and the 5881's. Everywhere I look they are saying el34 power tubes from the factory and for replacement. Maybe that helps for further comments. Thanks!
Jeff_H
Dean Hardtail Fanologist
Re: Jcm 600 and 5881's
I had a JCM 600 for a while in 2002 or 2003. It had EL34's in it for sure. It was a nice sounding amp, but just a little too "polite" for me ultimately. Regardless, unless it's been modified it should run the 34's, but I'm no electrician or amp tech. I also don't know if they had different versions that ran different power tubes.
I had a JCM 600 for a while in 2002 or 2003. It had EL34's in it for sure. It was a nice sounding amp, but just a little too "polite" for me ultimately. Regardless, unless it's been modified it should run the 34's, but I'm no electrician or amp tech. I also don't know if they had different versions that ran different power tubes.
Re: Jcm 600 and 5881's
Thanks Jeff. I've also emailed Marshall. Really excited for this amp. Seen some great YouTube videos, that sound really good. If Marshall responds that it should have EL34's, I've got to believe that's half of the problem! Thanks for all the advice from you and everyone else!
Jeff_H
Dean Hardtail Fanologist
Re: Jcm 600 and 5881's
I hope you get the news that it will work with the EL34's.
I had the 2x12 combo too and that was my first experience with the G12T-75 speakers. They were well broken in by the time it came to me and they sounded great. The sound of the amp was very warm and smooth, but not in a dark way. There was plenty of nice highs and mids as well..... and the cleans were nice. Much nicer than the cleans of the JCM 800 that replaced it. The 600 was my first Marshall and I knew practically nothing about tube amps. I'm positive that I could have tailored the sound a bit by using different pre-amp tubes or even power tubes.
It should give you a great range of blues, rock and hard rock on it's own. With a couple of pedals it should do most anything you want. I too found many positive reviews before I purchased mine, so I was confident in buying it.
Let us know what you find out and more importantly how it sounds once you get the power tube situation sorted!
I hope you get the news that it will work with the EL34's.
I had the 2x12 combo too and that was my first experience with the G12T-75 speakers. They were well broken in by the time it came to me and they sounded great. The sound of the amp was very warm and smooth, but not in a dark way. There was plenty of nice highs and mids as well..... and the cleans were nice. Much nicer than the cleans of the JCM 800 that replaced it. The 600 was my first Marshall and I knew practically nothing about tube amps. I'm positive that I could have tailored the sound a bit by using different pre-amp tubes or even power tubes.
It should give you a great range of blues, rock and hard rock on it's own. With a couple of pedals it should do most anything you want. I too found many positive reviews before I purchased mine, so I was confident in buying it.
Let us know what you find out and more importantly how it sounds once you get the power tube situation sorted!
Last edited:
Re: Jcm 600 and 5881's
No problem sir! I'm trying to sort this out too!��
slightly_rude
New member
Re: Jcm 600 and 5881's
I found this in a Marshall catalog I have that was published in Feb. 1998
EL34s.......Svetlana's no less before they were marketed as SED.
Sent from my SM-G930V using Tapatalk
I found this in a Marshall catalog I have that was published in Feb. 1998
EL34s.......Svetlana's no less before they were marketed as SED.
Sent from my SM-G930V using Tapatalk
Re: Jcm 600 and 5881's
Rude: That is awesome! Thank you for that info! That's the consensus of the info I'm finding, being EL34's. It's no wonder the amp doesn't sound right. Marshall hasn't responded yet. I'm going to order a new set of tubes and some bias tools. Still working on pics. Thanks again! ��
I found this in a Marshall catalog I have that was published in Feb. 1998
EL34s.......Svetlana's no less before they were marketed as SED.
Sent from my SM-G930V using Tapatalk
Rude: That is awesome! Thank you for that info! That's the consensus of the info I'm finding, being EL34's. It's no wonder the amp doesn't sound right. Marshall hasn't responded yet. I'm going to order a new set of tubes and some bias tools. Still working on pics. Thanks again! ��
BloodwynPig
New member
Re: Jcm 600 and 5881's
Yay my first post. Long time lurker,but saw your question and decided to register. I have an almost original (clipping diode mod) JCM600 head that I love. Clean is great for a Marshall and it roars. I don't know if this will be helpful to you, but Marshall sent me an owners manual and schematic for the amp. Take the schematic with a grain of salt as I've noticed errors.Good luck and let us know how you fare!!:beerchug:
Sorry for the poor quality. Was running into space constraints. If you want a higer res copy of anything let me know. Not sure these will be helpful , but if someone runs across the thread later they may be.
Cheers and good luck!
Yay my first post. Long time lurker,but saw your question and decided to register. I have an almost original (clipping diode mod) JCM600 head that I love. Clean is great for a Marshall and it roars. I don't know if this will be helpful to you, but Marshall sent me an owners manual and schematic for the amp. Take the schematic with a grain of salt as I've noticed errors.Good luck and let us know how you fare!!:beerchug:
Sorry for the poor quality. Was running into space constraints. If you want a higer res copy of anything let me know. Not sure these will be helpful , but if someone runs across the thread later they may be.
Cheers and good luck!
