Hey guys I have a JTM 45 with el34m power tubes now, was thinking about putting 5881 power tubes in it. Question is what is the sound difference? I want the cleanest, tightest sound I can get. Now the el34m tubes are a little spongie, or have a sag to them when turned up a bit. So if someone can help me out on the sound difference that would be great. Also I play a Les Paul with a JB in the bridge if that helps.
5881 vs el34
- Thread starter rgreen11
- Start date
C-Martin
New member
Re: 5881 vs el34
a jtm-45 isnt a real jtm-45 unless you got KT-66 in them!
:joke: interesting that you say ou have a jtm-45 with ELs... i was pondering trying to switch from KTs to EL34s and see if it gave me a bit more of a marshall plexi vibe to it.. mine used to have 5881's in it and from what i remember the sound is glassier, less low end torque to it but cleaner sounding overall. I kinda miss some of the glassiness my amp had with those tubes..
a jtm-45 isnt a real jtm-45 unless you got KT-66 in them!
:joke: interesting that you say ou have a jtm-45 with ELs... i was pondering trying to switch from KTs to EL34s and see if it gave me a bit more of a marshall plexi vibe to it.. mine used to have 5881's in it and from what i remember the sound is glassier, less low end torque to it but cleaner sounding overall. I kinda miss some of the glassiness my amp had with those tubes..
Re: 5881 vs el34
if you want a great tight clean tone get something like an rca style 6L6. 5881 is a military 6l6 and can be great tubes but ive found that rca style 6l6's sound best clean in simple circuits. i love the ge style but they arent as tight and seem to break up earlier. if you have the bucks to get a real set of kt66's and the power tranny can handle it, it is a beautiful sound. big bold and tight even when it starts to break up a little
if you want a great tight clean tone get something like an rca style 6L6. 5881 is a military 6l6 and can be great tubes but ive found that rca style 6l6's sound best clean in simple circuits. i love the ge style but they arent as tight and seem to break up earlier. if you have the bucks to get a real set of kt66's and the power tranny can handle it, it is a beautiful sound. big bold and tight even when it starts to break up a little
Lake Placid Blues
New member
Re: 5881 vs el34
JTM45 spec trannies should handle the heater current easily. KT66s pull 1.3 amps. Slightly less than EL34's. The current production Russian "Gold Lion" KT-66's seem to be pretty good as a cost effective alternative to used GEC KT-66. The current =C= 6L6GC is a solid bottom tube too.
JTM45 spec trannies should handle the heater current easily. KT66s pull 1.3 amps. Slightly less than EL34's. The current production Russian "Gold Lion" KT-66's seem to be pretty good as a cost effective alternative to used GEC KT-66. The current =C= 6L6GC is a solid bottom tube too.
Chickenwings
Alnico 6/8
Re: 5881 vs el34
If you want more headroom and more bass without "sponginess" then you can install some 6CA7 tubes - electro harmonix make some new these days. They are the same as an EL34 but in a bigger bottle and built to higher specs so they can tolerate more voltage. More clean, more ability to handle bass - they work great in my musicman. 6CA7 is really just military spec EL34 so a perfect match for your amp if you want it to sound "bigger".
If you want more headroom and more bass without "sponginess" then you can install some 6CA7 tubes - electro harmonix make some new these days. They are the same as an EL34 but in a bigger bottle and built to higher specs so they can tolerate more voltage. More clean, more ability to handle bass - they work great in my musicman. 6CA7 is really just military spec EL34 so a perfect match for your amp if you want it to sound "bigger".
glassman
Electron Herder
Re: 5881 vs el34
If this amp is an original JTM45, I'd suggest you have it converted back to its original configuration and either sell it and get something more suitable for your needs or rock it as it's supposed to be...there's gonna be a little sponge to it.
If it's a reissue, take it to a tech and have him:
(1) use a plug in solid state rectifier
(2) increase the filter cap value to the first node of the B+
(3) convert it back to 5881/6L6 and use a jj 6L6, winged C 6L6 or a Ruby 6L6GCMSTR. Which ever you use, have your tech bias it on the hot side.
(4) increase the negative feedback by changing the series resistor to one that is half the value of the current one.
If this amp is an original JTM45, I'd suggest you have it converted back to its original configuration and either sell it and get something more suitable for your needs or rock it as it's supposed to be...there's gonna be a little sponge to it.
If it's a reissue, take it to a tech and have him:
(1) use a plug in solid state rectifier
(2) increase the filter cap value to the first node of the B+
(3) convert it back to 5881/6L6 and use a jj 6L6, winged C 6L6 or a Ruby 6L6GCMSTR. Which ever you use, have your tech bias it on the hot side.
(4) increase the negative feedback by changing the series resistor to one that is half the value of the current one.