RM100- Never got it to sound right, where am I going wrong?

I bought my RM100 about 4 yrs ago. I had really high hopes after everything I'd read on these forums. It's obviously a great piece of equipment, but I've been struggling with mine since day 1.

I bought the head brand new, still in the box. Same with the modules. My RM100 is currently loaded with the only 3 modules I've ever purchased, Blackface, SL+, and XTC. I'm admittedly running it through a pretty lame Marshall MG412A cab.

Since the day I bought this thing, the Blackface is the only module that has sounded halfway right to me. The SL+ and the XTC both have a terrible flubby, buzzy character to the distortion, almost like a blown speaker. Also, the XTC sounds about 90 percent similar to the SL+. I know what a Bogner Ecstasy sounds like, and I've listened to Youtube clip of other XTC modules and mine sounds nothing like them. Way less gain, and no focus at all. It sounds like a Gorilla amp.

I initially figured it was a bad output tube, maybe it is. I set the bias on the tubes at 34 mv. I've checked all the fuses and they are fine. I've tried pulling each pair of tubes and I feel like I hear some improvement but not much. Maybe its just wishful hearing. However, the effect is the same for each pair.

I've plugged my guitar straight into the effects return and when I play it I don't notice any offending sounds. My impression is that means the output tubes are OK.

I suppose the buzzy quality I'm hearing might point to an input tube. Im not sure how to check those short of replacing them one at a time .I guess I could replace the V1 tube first as that seems the more likely culprit since it would effect both modules.

One last consideration that I have no idea how to test. My house is almost 100 yrs old and I'm sure the wiring is all kinds of goofy. Would low/high voltage coming out of the mains make this dramatic of an effect?

I know 12ax7's are cheap, so replacing V1 is my next step, but I'd like to hear what some of you guys think would be possible causes and courses of action. I's sure some of you here can help me solve this before I waste another chunk of change replacing all of the tubes. I'm heartbroken, knowing the potential of this amp and just letting it sit unused.

Thanks a ton!!

Speakers will have the biggest impact on tone. Have you tried it with a different cabinet?

Rolling preamp tubes is pretty much the first thing anyone here does to dial in the tone on a module. Also many people have preferences on the PI tube and the power tubes they use.

What preamp and power tubes do you have installed?

The modules you have should sound decent but maybe not spectacular. Most everyone here runs modded modules at this point. I would get the other options sorted before you fork out money for a modded module just yet though.

Most everyone here runs modded modules at this point.

+1

Many salvation modules will not leave you indifferent and will heal your heart)))

I'm so embarrassed after re-reading my original post. Input tubes and output tubes, what the hell? I'd been doing a lot of reading on transformers before I posted so maybe that's where that came from.

Anyhow, I'm pretty sure all the tubes are JJ's. The power tubes are 6L6GCs and the preamp and phase inverter and EC883's. I'm not sure whats in the modules because I didn't have time to check.

I'd love to get some modded modules, I really wanted a couple way back when I bought this thing. I just can't make myself spend any more on this thing until I get it sorted out. It wouldn't make any sense to spend a few hundred bucks on a module for it to sound like garbage too.

At this point, I'm guessing it has to be one of the EC883s. I guess I'll just order a couple and start swapping those around and see if it helps.

MarcoR said:

I would get the other options sorted before you fork out money for a modded module just yet though.

Click to expand...

I'm with Marco on this - this would be my hit list (in order):

• Preamp tubes - get some good quality ones in there (I like Ruby 12AX7 HG & JJ's) and a 5751 in the Phase Inverter (PI) tube position.
  Swap out the tubes in the modules too (more 12AX7's basically).
  Get the power tubes tested and replaced where needed!
  Get something to clean the power supply (voltage regulator).
  Get a better cab to try (even if it's only a good quality 2x12, Marshall 1936 Vintage or better), speakers are really the biggest and most over looked component in your signal chain, but good cabs are really quite expensive!
  Get a Foglifter / MDA board from Jaded Faith / Salvation.
  Think about modding the modules

IMHO the SL+ should sound good - I've got both modded and unmodded and they all kick butt (mine are the silver face ones) but I always thought the stock XTC sucked quite badly

Hope some of that helps!

The first thing would be speakers. You've get a very....un-awesome cabinet with even less so-so speakers. When I got my first tube head, a Marshall DSL100, I loved it at the store but when I played it through my Crate 4x12s, it sounded like complete garbage. I was using some nice axes at the time so I know that wasn't the issue. I put the head up for trade and I'm glad no one wanted it because I bought a Marshall 4x12 with V30s and HOLY EFFING CRAP, the amount of difference I had was friggin' incredible.

In my opinion, crap cabs make anything sound like crap, but a great cabinet can make terrible heads sound awesome.

Just a small bit from a 23 year old gearhead.

JJ tubes aren't the most dynamic preamp tubes if you ask me
they lack a little 'life' (though are very good at subduing shrilly preamps)
and that MG cab won't help matters further (if not worst as Webrthomson said)

Nightdare said:

JJ tubes aren't the most dynamic preamp tubes if you ask me
they lack a little 'life' (though are very good at subduing shrilly preamps)
and that MG cab won't help matters further (if not worst as Webrthomson said)

Click to expand...

I totally agree. jj preamp tubes are a little dark and dull sounding. On the topic of preamp tubes, you should try and buy a few different brand of tubes.
The coolest thing about the mts line up is every little change has a noticeable difference, more so than other amps.
The cab is probably your biggest problem. Did you ever use the cab with another amp and it sound good to you?
I would highly suggest you try the tubes, and cabinet first before you start spending money on upgrades like modded modules. The modded modules are off the chart but it's a lot of money to throw down if you just don't bond with the amp in the first place.

Thanks for all the replies. I'm definitely going to try a few different preamp tubes and see what that does.

Maybe the cab is the problem. I don't really know where I'd find another to try out without just buying one. If the preamp tubes don't solve the problem, new cab it is I guess. I knew the cab was less than ideal when I bought it, but the $1200 I'd just dropped on the head unfortunately made me cheap out on the cab. Now I'm THAT guy. The one playing the kick-*** amp through the garbage cab and trying to figure out why it sounds bad. Im like the guy playing the Murphy aged 59 Les Paul RI through an Esteban amp.

You might go for a quality 2x12 cab with good speakers. I have an Egnater 2x12 with an oversized cab and custom Celestions (stock in the Eggie stuff) and I think it sounds great.

can you haul your head to a local music store to test some cabs? If you can plug it into a few quality cabs, you can at least identify (or discount) your own cab as the source of your troubles.

If it still sounds like garbage, the problem lies elsewhere or maybe this amp just isn't for you.

If it sounds kickass, you can play on knowing that when you finally have the funds for a good cab, tonal nirvana awaits.

+1 on the cab... The cab & speakers are as big a tonal ingredient in your rig as the amp itself and the guitars.

BTW - I run JJ 12AX7's pretty much everywhere in my RM100, except for the PI, where I have a vintage/JAN 5751. I've rolled through several different brands of pre-tubes, ie Tung-Sol, EH, etc. I personally prefer the JJ's, as I've found them to be 'fatter', and possessive of more complex harmonic content. My rig sounds great with them, an the pre's wont have near the affect on tone as the cab/speakers. Unless there's is a defective tube, I'd be looking into the cab as the most likely culprit...

You should take your head to a local music shop that has a variety of cabinets in stock and tell them you are looking to buy a cab and would like to demo the cabs with the actual head you will be running into the cab.

I just wanted to give you guys a little update. I got some new tubes in today and what a difference that made! I put a 5751 in the PI and replaced the v1 with a different EC883. Not only do the distorted sounds of the SL+ and XTC sound considerably better, the clean Blackface tone is SOOO much sweeter sounding.

I haven't made any headway on my garbage cab yet, 70 hrs at work this week got in the way a little. This thing sounds pretty good with the new tubes, I can't wait to hear it through some decent speakers! I think I've far underestimated the importance of speakers all along. Anyone have any recommendations for a good 2x12?

Finally, while my XTC sounds way better, I feel like something still doesn't add up with it. It's actually a pretty good sounding module, it just doesn't sound like it's supposed to (I think.) Maybe I'm expecting too much, but it doesn't have any more gain than my SL+. It falls short of others that I've heard and doesn't really sound like an Bogner to me. I'm sure it's one of the very early XTC's, which I think are generally regarded as not so great.

Thanks for all the help. It's great that there's still people going strong with the MTS amp and dishing out help. Its taken me a few years, but I think with a new cab, I'm going to have this amp singing!!

mbach1972 said:

I just wanted to give you guys a little update. I got some new tubes in today and what a difference that made! I put a 5751 in the PI and replaced the v1 with a different EC883. Not only do the distorted sounds of the SL+ and XTC sound considerably better, the clean Blackface tone is SOOO much sweeter sounding.

I haven't made any headway on my garbage cab yet, 70 hrs at work this week got in the way a little. This thing sounds pretty good with the new tubes, I can't wait to hear it through some decent speakers! I think I've far underestimated the importance of speakers all along. Anyone have any recommendations for a good 2x12?

Finally, while my XTC sounds way better, I feel like something still doesn't add up with it. It's actually a pretty good sounding module, it just doesn't sound like it's supposed to (I think.) Maybe I'm expecting too much, but it doesn't have any more gain than my SL+. It falls short of others that I've heard and doesn't really sound like an Bogner to me. I'm sure it's one of the very early XTC's, which I think are generally regarded as not so great.

Thanks for all the help. It's great that there's still people going strong with the MTS amp and dishing out help. Its taken me a few years, but I think with a new cab, I'm going to have this amp singing!!

Click to expand...

Trade out your tubes every year or two depending how often you play....That really helps....I have a little Orange Tube Tester that tells me where my tubes are in their life cycle which is helpful...Otherwise forget brands and keep some cheap fresh tubes on hand for swaps if need be....Fresh tubes are the best tubes....

Mattfig said:

....Fresh tubes are the best tubes....

Click to expand...

Yet most amps sound best after they've been "burnt in" :twisted:

Nightdare said:

Mattfig said:

....Fresh tubes are the best tubes....

Click to expand...

Yet most amps sound best after they've been "burnt in" :twisted:

Click to expand...

I buy my tubes already burned in...

I'd look into the Avatar 2x12's they sound pretty amazing to me.
I have two one with V30's closed back and one with Vintage Altec 417's open back a fantastic combo. they run about $430 with V30's and go up from there. You can find them on the used market for around 300 to 350.

I found a huge difference in just doing the orange cap mod to my SL+ and XTC. Much tighter and more pleasant low end.

Definitely the cab is holding you back.
I have some nicer cabs like a Carvin Legacy cab with v30s in it and I don't really even like the low end on that, compared to an Orange or Engl Cab.
Different cabs affect the tone almost as much as different modules.