What are the lowest volume power tubes you can use?

[Big Steve]

I just got introduced to these amps over the weekend at the LA Amp show by Rob of Jaded Faith. They sound awesome with his modules. He said that the 50RM could take any octal power tubes. I see people on this forum talking about using 6V6's which a pair will give you about 22 watts. Anyone using 6K6's which would give you around 10 watts? Do they work in this amp? Are there any other low volume tubes you can use in the amp? Thanks for your help.

 

[wesarvin]

Welcome to MTS. Prepare for the addiction.

Lets just say that 10 watts is still pretty stinking loud. You'll mainly lose headroom when going lower wattage, not so much volume. Unless you can try this for yourself, check out Bruce's article in a sticky on this forum.

Btw, I once put my Valve Jr in a 4x12 next to my rm50 combo. They were about the same volume, granted one had punch and the other sounded like monkey farts. There's a master volume control for a reason.

 

[Big Steve]

Thanks for the input. Yeah I know 10 watts is loud. I have both small and big amps. I want power tube distortion, not preamp distortion. About 15 watts is perfect for most of the gigs I do. I like to run the master wide open. That is why I am trying for lower wattage. I am into Fender tweed and black face tones. I had a Univale amp and I loved swapping tubes but the preamp wa just too aggressive for me. With the chance to change both the preamps and the power amps, this amp might be perfect for me. It will allow me to sell a lot of amps.

 

[gag halfrunt]

As I'm sure you know, different power tubes will alter your tone in very different ways. I bought an RM 20 because I wanted a portable MTS platform, but I didn't like how the small bottle tubes sounded with my modules. I'd prefer to use an RM 100 with the good master volume that it has.

Even better, combine the big bottle tubes (your preference EL34s vs 6L6s) with a Rivera Rockcrusher attenuator, and you'll get that beautiful power tube distortion with usable volume.

And before you say you don't like what attenuators do to your tone, I'll tell you I was the same way. I tried just about every one made, including the expensive ones, and they all seemed to suck tone. But then I tried the Rockcrusher, and it was amazing. Best. Attenuator. Ever.

 

[wesarvin]

Totally understandable. From my experience with the amps thus far, the modules all tend to sound similar once you start pushing the power tubes too hard, especially the el84 based amps. Most of the grit and grunt in most power tube breakups is actually modeled quite well with the modules. Of course, cranking the amp until its just a hair of breakup is best.

The biggest difference in tube types is gonna be headroom, feel, and tone. Not so much volume.

 

[joey_truelove]

I just got introduced to these amps over the weekend at the LA Amp show by Rob of Jaded Faith. They sound awesome with his modules. He said that the 50RM could take any octal power tubes. I see people on this forum talking about using 6V6's which a pair will give you about 22 watts. Anyone using 6K6's which would give you around 10 watts? Do they work in this amp? Are there any other low volume tubes you can use in the amp? Thanks for your help.

Welcome Big Steve. I think I've seen you elsewhere online so I'm delighted you've found your way here.

Those 6V6s that can accept the voltages we talk about are the JJs and I believe even at that the output impedance will be a mismatch. They sound and are built much like short bottle 6L6s anyway.

Another way is going EL84s in adapter sockets and I know TAD has ones that run them in triode mode for even lower volume.

But as stated it's still bound to be loud and I for one prefer running mid power octals biased hot to make them softer and distort earlier. You'd basically need big och mid octals for that bottom end thing of a high power amp. EL84s are just lighter and softer and running them in triode-mode would make them even softer/ spongier sounding.

 

[Big Steve]

I really like the size of the rm20 but I don't like EL84 tubes. I just don't like their clean tones.

So are you telling me I can only use JJ 6v6's? I have plenty of nos heavy duty 6v6 tubes.

 

[drewiv]

So are you telling me I can only use JJ 6v6's? I have plenty of nos heavy duty 6v6 tubes.

That's what the manual says.

 

[joey_truelove]

I really like the size of the rm20 but I don't like EL84 tubes. I just don't like their clean tones.

So are you telling me I can only use JJ 6v6's? I have plenty of nos heavy duty 6v6 tubes.

Your biggest potential issue with 6V6s and 6L6Gs lower than C-rating is the plate voltage. Does anyone know what kind of voltages we can expect in an RM amp?

I believe the 5881/ WGB were designed for 360V max though possibly they can go beyond 400V if well built. 6V6GTs are rated at a mere 315V DC. Of course you could give it a try but it will inevitably be pushing it quite a bit.

Drewiv is probably correct in regards to what's being made today, which is of lesser quality than NOS.

There are various ways of lowering headroom while staying with EL34s, 6L6GCs and similar octals though, but with the exception of biasing may require modifying or re-building the amp to some degree.

An attenuator may after all be your best bet here, I'm afraid.

 

[DonP]

I want power tube distortion, not preamp distortion.

I've only had RM100's for a couple of weeks but I am not sure if this is the right amp for power tube distortion. From what little I've seen, this technology seems concentrated on the preamp modules for shaping the tone and using a standard solid back end for pushing a 4x12 cab.

I'm thinking you might be better off with something that has a tube recifier and is a combo. Fender Bassman comes to mind.

If you liked the tones Rob with Jaded Faith was producing, then maybe try to replicate that setup that you liked?

 

[drewiv]

I want power tube distortion, not preamp distortion.

I've only had RM100's for a couple of weeks but I am not sure if this is the right amp for power tube distortion.

I tend to agree with your assessment, Don P. As many around here know, my all time favorite MTS rig was an M4 or RM4 connected to my VHT 2|90|2. Talk about head room on the KT88s, but talk about the world's heaviest rig.

MTS rigs are mostly about preamp distortion, IMO. Which is also why they sound "good" at lower levels. This is just my $0.02.

 

[DonP]

I was still thinking about this. If you really wanted power tube distortion I guess you could take the line out from the preamp and run it to a lower powered slave, like an Epiphone as was mentioned earlier.

Silly thought because who would want to lug around a heavy 100 watt amp and not even use it.

 

[Big Steve]

Thanks for the help guys. I am going for the 50 watter not the 100. The 50 is still heavy and loud though. I am really just trying to understand the capabilities of this amp. When I read that chart, I was thinking the bias numbers he set for the 6v6's was for the JJ's, but I thought you could bias the amp lower than those settings. Maybe you can't.

The tweed Fender module that Jaded Faith had at the show sounded really good even at lower volumes and he had 6l6's in that particular amp. So maybe I will be set with 6L6's.

 

[joey_truelove]

The tweed Fender module that Jaded Faith had at the show sounded really good even at lower volumes and he had 6l6's in that particular amp. So maybe I will be set with 6L6's.

Could go with those short bottle GCs or 'WGCs', like the TS or the TAD, which are said to prefer around 55% (16.5W) biaslevel for a sweet breakup. Though as previously discussed that would make a difference of two or three dBs.