Mixing Power Tubes in RM100

[mfred]

Does anyone have any experience mixing power tubes in a RM100?
I've been told I could mixpower tubes such as EL-34's and 6550"s. If so does anyone know where they should go.. example 6550's in the two outside positions (1,4 looking from the back) and EL-34's in the two inside positions (2,3 looking from the back). Any specific combinations that you've found that are especially killer. Thanks

Mike

 

[Julia]

I would say that it makes a difference if you're playing really loud at gig volumes with your master over noon. If you're practicing with the Master volume at 10 I don't think you'll notice much of a difference. EL34's break up way earlier than 6550s. I wouldn't want to be in the same room if you can get 6550s to breakup. 6550s = massive clean headroom.

If you want power tube distortion try the JJ 6v6s or THD Yellowjackets.

 

[KillTone]

The power tubes run in pairs, as you probably know. The outside tubes are a pair and the inside tubes are a pair. Some people have said that the inside pair dominates the tone of the amp. I am not sure if there is any truth to that.

I use a pair of EL34's on the outside and a pair of KT88's in the middle. LOVE the tone. Some of the EL34 midrange voice with the big soundstage and headroom of the KT88s. I get some power tube break up at gig volumes but it is manageable. I have used smaller tubes that will not clean up once the amp really gets cooking.

 

[eedude]

Some people have said that the inside pair dominates the tone of the amp. I am not sure if there is any truth to that..

yeah, i don't think there is any truth to that. V1 and V2 locations are identical and V3 and V4 locations are identical. So you can pair:
v1-v3
v1-v4

v2-v3
v2-v4

it's all the same....

since you can set the bias for each tube it would be really interesting to use four different tubes!

 

[KillTone]

Four different power tubes?!!

How would you set that up? What bias setting would need to match? Not sure that I am really brave enought to try that.

You have WAY more electronics knowledge than I do - try it and let me know how it works out :lol:

 

[eedude]

yeah, i duno if I'm brave enough to try it...or willing to spent the money on a bunch o different tubes

but the theory is simple, just bias each tube per it requirement...the output is not going to be symmetrical.. but hey who knows....

the fact that the RM100 has a bias adj per tube is so awesome....

 

[Mattfig]

4 dif power tubes??? That might be quite dumb to be honest....You need some consistency between modules..You'd be better off using 4 different speakers...4 dif power amp tubes is gimmicky at best...A set of EL34s mixed with 6550s seems to be the best way to cover all bases safely and in a very cool fashion...6L6s will be a nice combo with 34s...Just remember, if you're using a Brit voiced module, stick to 34s....It should be law...I think as set of Winged C SED EL34s combined with some JJ El34s would sound pretty cool...

 

[eedude]

fig, it was meant in jest... but you should not be too hard on the idea...
i mean there are folks that scoff at tubes and think that designing circuits that have distortion is dumb...

I have no idea how it would sound, but remember that triode tube preamp distorts in an asymmetrical way...the truth is in the tone...

alright who's gonna do it just to report on it?

 

[eyeball987]

I use 6550's in the middle and 34L's on the outside. Works best for me.

 

[Mattfig]

fig, it was meant in jest... but you should not be too hard on the idea...
i mean there are folks that scoff at tubes and think that designing circuits that have distortion is dumb...

I have no idea how it would sound, but remember that triode tube preamp distorts in an asymmetrical way...the truth is in the tone...

alright who's gonna do it just to report on it?

True, and no disrespect was intended...
"Dumb" was not the right choice of words...Seems it could be interesting and I'd like to hear it if someone were to try it...But I know there's a reason amps manufacturers don't do this...Nonetheless, you are so right about how cool it is that each tube has its own bias...Awesome feature....

 

[crankyrayhanky]

Some people have said that the inside pair dominates the tone of the amp. I am not sure if there is any truth to that..

yeah, i don't think there is any truth to that. V1 and V2 locations are identical and V3 and V4 locations are identical. So you can pair:
v1-v3
v1-v4

v2-v3
v2-v4

it's all the same....

since you can set the bias for each tube it would be really interesting to use four different tubes!

I know next to nothing about tech stuff, but from what I've read this is FLAT OUT WRONG and HARMFUL

The inner and outer tubes are push-pull, mixing up tubes within those positions is not about bravery, it's about destruction

 

[eedude]

I know next to nothing about tech stuff, but from what I've read this is FLAT OUT WRONG and HARMFUL

hi cranky

which part is wrong, the tube association i noted or the idea of asymmetrical mixing tubes? I'd like to clarify as to not confuse or propagate wrong info.

The tube association as to the pairs is correct, unless i have the wrong V#'s....

The mixing of tubes I don't see how it can be destructive (based on how the circuit operates). It does put an asymmetrical DC idle current through the output tranny..I don't see that that could harm.. .. and the AC signal is going to get asymmetrical treatment.. but I don't see that that would harm either.. But I will retract that someone should go try it. I will try it when I have the time and report back... I don't have anything exotic, just 6l6's and el34's so i would expect little excitement. :wink:

 

[Ampoholic]

I use SED winged "C"s, 6L6 inside, EL34s outside.

As far as using 4 different power tubes, I've never read anywhere that it SHOULD be done. Whether it's technically possible or not, I don't know. But I did a LOT of research before even trying 2 different types of tubes. I beleive I found where Randall people agreed or stated 2 types were okay, in pairs, inside and outside.

PEACE!

 

[nomad100]

the problem just might be with the DC voltage. SE amp have an air gapped OT because of the DC on the tranny. PP amps don't need that because of idk i understand it but can't word it.

 

[nomad100]

btw 2 6l6's and 2 kt77 rock pretty hard!

 

[crankyrayhanky]

Randall people agreed or stated 2 types were okay, in pairs, inside and outside.

This sounds right; putting 4 different types in sounds bad

 

[laxcdn]

I did 2 e34l's on the outside and 2 6l6 and I found it gave it more headroom and a bit more punch. The Lynchbox uses el34's instead of 6l6's

 

[nomad100]

i took the kt77's out of my amp the 2 6l6's and 2 kt77 gave me a great metal hardrock tone. Right now i just have 2 6l6's in my amp a lot easier to get a decent lower volume tone that way. Throw on my homemade attenuator and i'm rock at 12 watts.

the KT77's made the amp feel a little stiffer.

 

[panther_king]

Yeah, 2 different pairs sounds safe to me, but 4 different tubes... not so much.