M4 & RT2/50 master volume problem

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I cannot run my M4's master volume any higher than 9 to 10 o'clock (25% to 30%) or it starts sounding harsh through my RT2/50. If I keep the M4 master low, both channels of the RT2/50 sound fine at any level. FYI, I'm running the master vol's of my high gain modules around 10 o'clock.

This isn't a show stopper but I feel like I'm not getting the volume I should be getting. Is it normal for the M4's (usable) MV level to max out at 30%?

Is it possible that the preamp tubes in my M4 and/or RT2/50 are clipping when the M4 is at higher levels?

I'm running TungSol 12AX7's in V1 and V2 on the M4.
I'm running a GE 12AT7 in PI and 2 x TungSol 12AX7's on the RT2/50. Power tubes are JJ 6L6GC and =C= EL34.

Any advice would be great. Thanks!
 
Go into more detail about "harsh".

Also, why the 12AT7 in the PI? Is the Rt250 spec'd for that?

I've never gotten a great tone out of a 12AT7. It could very well be that by overdriving the 12AT7, you're getting harshness.

Despite what people claim, the 12AT7 really isn't a good low-gain substitute for a 12AX7, even thought the pin layout is the same and it functions when plugged in. It's totally different tube made for totally different purposes. Not a good tone tube at all.
 
I run the RT at 3:00 and the master on the M4 at about 9:00 at it is so loud that I cannot even hear myself type but not harsh and the more master on the M4 the louder it gets(unfuckingbelievably)loud,but not harsh.
 
Have you tried a different power amp to try to sectionalize the trouble??

I've had bad luck with the Tung Sol 12ax7a tubes. I would start by swapping those out of the M4 and see if tha fixes your problem. I also agree with Nick, get the 12at7 out of the PI on the power amp.
 
12AT7 is really more of a "utility" tube. Reverb driver, etc. Not really tone-y.

A 5751, on the other hand, *IS* the same as a 12AX7, but just 80% of the gain.
 
Thanks for the suggestions. :thumbsup:

When I get a chance I'm going to run the M4 into the power section of my 5150 to see if it's the M4 that's giving me trouble. I may also try running a different preamp into the RT2/50.

On the RT2/50 I pulled the 12AT7 from the PI and replaced it with a balanced TungSol 12AX7. I tried TungSol 12AX7's in Ch A and B but they sounded to chimey so I put in Sovtek 12AX7WA's.

On the M4 I made the same conclusion with the TungSol's being too chimey and replaced them with Sovtek 12AX7WA's.

After these changes there was a definite improvement both in volume and sound. When I crank up the M4 master it no longer sounds harsh. However, anything past half way on the M4 master starts sounding overly compressed. The compression is there even when the master is low on the RT2/50. It's like the M4 is overdriving the RT2/50 input (in a bad way). Do you think this has something to do with the TungSol in the PI position? I don't have any other balanced 12AX7's to try (other than EH, yuck) but I'm thinking about ordering a balanced Sovtek WA.

What tubes do you guys recommend in the M4 and RT2/50? Any thoughts on the compression issue?
 
I normally run everything through my Switchblade 8 with some reverb/delay mixed in parallel. When I noticed I had a problem, I plugged the M4 directly into the RT2/50 to bypass the Switchblade. Even when running direct, the compression issue is still there when the M4's master is more than halfway.

While running through the Switchblade, I checked the VU meter for the M4 output level and it was hovering around -8 db. So the M4 doesn't appear to be clipping the Switchblade loop.

By process of elimination, it seems like the problem is with the RT2/50. I will try running the M4 into another power amp and a different preamp into the RT2/50 when I get home tonight.

As a side effect of running direct, I noticed I'm losing a bit of high end while running through the Switchblade. I'm going to check/replace my cables to see if they are causing the coloration.
 
I know there's a PI for each channel...but isn't one of the three 12ax7 tubes in the RT2/50 an input buffer (the middle one?). I'd suspect this if it's clipping/over compressing..or one of the chassis preamp tubes on the M4.
 
Most of my modules master vol. are from 12 to 5 oclock. I adjust the master on the M4 to control my overall vol. The RT2/50 volume is maxed then I back it off a notch. Just beautiful Tone!
 
Changing the PI tube to a lower gain one will not really reduce the loudness of the RT2/50 because of the negative feedback loop circuit but............. The extra 12AX7 in the middle radically affects the overall gain of the power amp. Try a lower gain tube in that position. FYI, the RT2/50 does have a fairly high input sensitivity which can, as you found out, cause some volume problems. I know of some players who found a 12AU7 to work well for reducing the "hotness" of the RT2/50 inputs.
 
Thanks eveyone. Thanks Bruce. :thumbsup:

For some reason I had the preamp tube layout backwards in my head. I thought the center position was the PI for both sides. :doh: I have balanced 12AX7's back in the PI positions and I will definitely try a lower gain tube in the center position.

I did some testing last night and made the following observations...

- The M4 still has some compression with the master volume at 60% or higher (through both the 5150 and RT2/50). However, this is much better than before when it was compressing with the M4 master at 30%.

- The M4 through the 5150's power section is super tight and punchy. I really like this sound, so I started trying to match it with the RT2/50 on the 6L6 side. My 5150 is running EH 12AX7's, so I installed EH 12AX7's in the PI and the center positions on the RT2/50. The EH in the center was too dark so I swapped it for a Sovtek 12AX7WA. The RT2/50 still seems a bit darker and definitely looser than the 5150, but it's pretty close.

- The Switchblade (M4 to RT2/50 loop) is robbing my tone of high end and definition. I tried several different cables and running direct from M4 to RT2/50 always sounded clearer with more highs. This was extremely surprising to me as I thought the Switchblade was supposed to be transparent!
 
Just to follow up my last post, I put a 5751 tube in the middle position on my RT2/50 and it's sounding a lot better. Everyone, thanks again for your help.

Now to figure out why my Switchblade is coloring my tone... must be the loop buffers.
 
ugg":3am9bjkl said:
Just to follow up my last post, I put a 5751 tube in the middle position on my RT2/50 and it's sounding a lot better. Everyone, thanks again for your help.

Now to figure out why my Switchblade is coloring my tone... must be the loop buffers.
Click to expand...


i find that when you put anything in between the pre and power section, it always robs a little of the highs, no matter how transparent the unit is supposed to be.

i look at it as a trade off.

i personally like the highs rolled off a bit, so i put up with a little coloration for the flexiblity. you can spend lots of money on expensive cables and expensinve buffers, it will always be there to some extent.

i know it kills you, but if you like the tone coming out of the rig ultimately i wouldnt sweat it too much.


can you tell me more about the rig that you are controlling with the 8b?

i am thinking of getting one.

stv
 
You are right about anything (except a patch cable) between the preamp and power amp affecting the tone. The best tones I have heard from my rig was when I ran Guitar -> M4 -> RT2/50 -> Cab. (Thank you Mr. Egnater!) Unfortunately, I need effects, so I have to settle for a slightly less pure tone. I try to not sweat it so much like you said, but I am cursed with a detailed ear and that makes me really anal about my tone.

I was using the Switchblade 8 (I don't have the 8B balanced version) primarily to mix dry tone with an effects processor set to 100% wet. The Switchblade allowed me to use an expression pedal to control the effects level. I've used the Switchblade for much more than this, however. PM me and let me know what kind of routing(s) you are thinking about and I'll try to help.

I was getting good tones through the Switchblade with the M4 master volume at 25%. The problem with this was I had to run the RT2/50 pretty high to keep up with my band (we play loud). This is when I discovered the tube issues with my RT2/50 and the additional loss of volume and tone through the Switchblade.

I'm currently having great success running Guitar -> M4 -> AxeFx -> RT2/50 -> Cab. Even though the AxeFx is doing A/D - D/A, it's surprisingly transparent, more so than the Switchblade. Also, the Axe has input and output level controls, so I can get higher levels into the RT2/50 for more volume.

One thing about the AxeFx, I found that the 4 cable method colored my tone way to much to be usable. Apparently the Axe's output 2 (Send) doesn't send a proper guitar level signal to the M4 input. So no pre effects (wah, drive, etc.) in front of the M4, but I can live with that.

I am using a GCX to switch between Guitar -> M4 -> AxeFx and Guitar -> AxeFx. This lets me switch between M4 preamp and AxeFx amp modeling. I might try using the Switchblade in place of the GCX. The Switchblade seemed to sound OK for everything in front of the M4.
 
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