Throttling Back My RT2/50

[Zaphod]

Hi, all -

Egnater M4 / Randall RT2/50 user here. This is my first forum post. I used to post and read about Egnater M4 info in the Egnater forum at Rig Talk, but hadn't checked in for a while over there and now I see that no one is talking modular, and now the modular talk is happening here!

I have had my M4 rig for 3 or 4 years now. One problem I always had was that the RT2/50 was just too loud for most situations and that I could barely get the amp breathing at any reasonable volume. And this was using the amp in switching mode, so I was dealing with 50W being too loud.

Based on some recommendations from RT2/50 users, I ended up ditching the original 6L6s and EL34s altogether, and using lower-output tubes. On one channel of the amp I have 6V6s, and on the other side I run YellowJacket converters in triode mode with EL84s. So on one channel I have ~22W and on the other ~10W. Even the low-power side is startlingly loud for such a low nominal output, and I have no problem keeping up in rehearsal or live gigging. I think part of this is because my speakers (Weber Blue Dog and Silver Bell alnicos mixed in an open-back 2 X 12) are so efficient that a little power goes a long, long way.

I keep the bigger tubes in my tool bag in case I need to blow walls down.

Anyhow, just thought I'd share!

 

[drewiv]

Welcome and this is where the modular talk happens, the rest of the work treats it as nonexistent.

The RT2/50 & RM4 combination is fantastic.

 

[JKD]

Nice...yeah, the RT2/50 seemed ungodly loud but the 6v6 and YJ is a good strategy.

I found the RM50 or MOD50 also works well...good master volume and the MOD50 has a half power setting..which is louder at the same master volume but of course about half-power...so it all evens out

 

[Nightdare]

There still is the old belief that 10W is 1/5th of the dBs, and that 100W is double the volume of 50W

IIRC, 10W is about 90% of a 50W's output and 100W only 1/10th louder

the only real use of lower output is that the tubes break up a little earlier
But that is still at levels that could damage your hearing

 

[Mattfig]

Hiya! RT2/50 running both sides is gonna be cray loud no matter what unless you attenuate the signal...I'm sure you get more flexibility with the smaller glass and probably some cool results but probably not a huge difference in volume...
How the tone with that setup? I'll bet Vox tones sing outta there!

 

[bruce egnater]

Try a 12AT7 or 12AU7 in the center socket. The issue is not really too much power. It has a lot of "gain" in the input stage making the sensitivity high. Let us know if this fixes it for you.

 

[Zaphod]

Hiya! RT2/50 running both sides is gonna be cray loud no matter what unless you attenuate the signal...I'm sure you get more flexibility with the smaller glass and probably some cool results but probably not a huge difference in volume...
How the tone with that setup? I'll bet Vox tones sing outta there!

The tones are very cool. It records well and gigs well on either channel. The EL84s in the Yellow Jacket triode converters break up pretty early and it's really easy to dial in whatever amount of power section saturation you want. At the point of dialing in a good gritty sound, increasing the volume level on that channel doesn't produce much more actual volume but increasing levels of saturation. That side pretty much peaks out at "just loud enough."

The 6V6 side is cleaner at equivalent volume levels and would be my go-to for crystalline clear tones at moderate levels. But push that side up and it will break up, too, but at a higher volume than the Yellow Jacket side.

I think a big advantage is that with the lower power tubes I get more of a range of volume control. With the high-power tubes it was very difficult to set a volume level as the volume knob was almost on-off at usable levels. And getting power section saturation was going to get me put in jail.

 

[Zaphod]

Try a 12AT7 or 12AU7 in the center socket. The issue is not really too much power. It has a lot of "gain" in the input stage making the sensitivity high. Let us know if this fixes it for you.

Bruce, thanks much for joining in.

So are you suggesting using a 12AT7 or 12AU7 in place of the middle 12AX7, and keeping the original 6L6 and EL34 (or similar) tubes? Will that lower the input gain to the power section?

 

[bruce egnater]

Yes. The preamp tube change will only reduce the input sensitivity, not the actual output power. This will just tame it own so it is not abnormally loud. The output power (watts) will still be determined by the power tubes.

 

[Zaphod]

Thank you. I will experiment with that and report back!