add a pre amp tube to the chassis?

[maximus1]

i think it would be great to add a pre amp tube to the rm100 as all other 100 watt amps have at least 4 pre amp tubes some even 5 and 6. i bet it would serve up more gain as well as tone. has anyone ever done this or know of someone trying this type of mod? i know it could be done

 

[TheAbomb12]

The RM100 actually has 9 preamp tubes when fully loaded (two for each of the three channels; 1 for input; 1 for FX loop; 1 for phase inverter). those other amps have multiple channels built in, and operate in a very similar manner to the RM100; However, most only have 1 tube per channel and then 3 for the input, Loop, and Phase inverter.

 

[maximus1]

yes i understand that but most high gain amps have 3 pre amp tubes then a phase inverter where as the rm100 only has 2 in the module then a phase inverter the other 2 tubes are for the loops

 

[metalmm785]

Remember u also got V1, which runs thru all the modules 2.

 

[Chad]

yes i understand that but most high gain amps have 3 pre amp tubes then a phase inverter where as the rm100 only has 2 in the module then a phase inverter the other 2 tubes are for the loops

Actually, this is the layout:

If you were to add another preamp tube, you'd have to do this mod too:

 

[maximus1]

any way you look at it there is only 3 pre amp tubes. 2 in the mod v1 and v2 then the one closest to the power tubes is the phase inverter v3. a tube in a mod that isn;t running isn't working then the other 2 tubes are for the loops. so adding one more on to the chassis would give you v3 instead of the phase inverter being v3 it would be v4 thus making it a normal tube amp set up tube wise anyhow. my 5150 had 5 preamps tubes for 2 channels. seemed to have much more gain on tap and was way less comppressed

 

[Chad]

Wow, I'm really at a loss as to what you're trying to say there.

In the pic above, the preamp tube in the far right side of the chassis is the V1 input tube/first stage of gain. This tube is active with all modules.

Then you have the two tubes in each module, which potentially adds 4 more stages of gain (1 stage per each triode...each tube has 2 triodes), but I don't know this for sure.

 

[TheAbomb12]

max, the RM100 has 3 tubes and then the phase inverter...

There is the input tube (V1) and then two in the module. 1 + 2 = 3.

V1 = Input, its active for all modules
V2 = Loop
V3 = Phase inverter.

 

[MetalMajik]

If I remember right, only one of the triodes in the input tube actually does anything. So it might be easier to figure out how to use the other half of the input tube as a gain stage rather than add a whole other tube

 

[3 Mile Stone]

Aren't there many modules available that currently have a sufficient, if not excessive amount of gain? Like the one called Mega High Gain?

 

[maximus1]

i could be wrong but in the module the tube on the left says v1 the one on the right says v2. so the modules houses v1 and v2. then the tube to the far left on the chassis is for the series effects loop then the next tube just set back and to the right of that one is for the parallel efects loop so that , the two loops are driven by 1 tube . then i guess that leaves the tube closest to the power tubes which is always the phase inverter so that covers all the tubes .

 

[Chad]

Yes, the modules have V1 and V2 written on them and I'm guessing they are that way because they are V1 and V2 on *that circuit board*.

V1 on the main chassis is the input tube and is active for all modules. This is explained in my RM50B manual and also by every other person in this thread.

 

[Chad]

BTW, my M/B 2 channel Dual Rectifier has 5 preamp tubes.

V1=input gain stage
V2=gain stages 2 & 3
V3=gain stages 4 & 5
V4=effects loop
V5=phase inverter

Point being that I don't see the MTS design as unusual or lacking at all as far as gain staging is concerned.

 

[TheAbomb12]

max, the serial and Parallel loops share ONE tube and ONE tube only. I know it sounds like crazy talk; but Bruce Almighty is an expert in the Dark Arts.