RM100.. too bright?

[nikki-k]

Ahh.. yeah, I wish I had a block diagram, but from alot of searching, only thing I do not have is MV position.

RM100:
guitar -> input -> V1a -> module selector -> MODULE -> MV -> Effects Loop (either/both?) -> PI -> Power Section -> speakers/load

Each module has the potential to utilize two tubes (called V1 and V2, even though V1 on the RM100, RM50, etc is the actual first triode for the initial gain stage, feeding ANY module used); those two module tubes provide up 4 triodes. All I have seen utilize a Cathode Follower for gain increase to feed the tonestack on that module, which would typically be "Module V2b." This leaves up to 3 triodes for gain manipulation or whatever is desired. As an example, a Marshall Plexi would have V1a for Normal, V1b for Bright; then hit the Gain pots, which then combine to feed V2a, V2b is a Cathode Follower for gain increase (NOT voltage) to feed the tonestack, and finally V3a+b for PI (long tailed pair).

So, with the RM100 (or RM50) as an example, "Amp V1a" is doing the initial gain; basically, not controlled by a pot or anything, simply raises the gain to a "workable" level. Through some components (probably) including a relay/switch to select which Module to be routed to. The module does not need the V1 ala Plexi example, as RM100 V1a has already done that job, and there is only one input, so RM100 V1b is unused.

Now inside the Module, typically V1a will follow the Gain pot on the front of the Module. This is "Module V1," not to be confused with the amp head's V1. For a true Plexi type circuit.. well, difficult since the RM10 only has one input. No (easy) way to create the blend of inputs via jumpers ala true Plexi. But, to continue, Module V1a would get used for the same amount of gain available on a Plexi, and then V2b (or one of the 3 remaining triodes) is used as Cathode Follower to feed the tonestack, and then it is out of the module via the Master Volume pot on the Module, and back into the main circuitry of the RM100. For, say, the SL+ (hot rodded Super Lead Marshall), V1b on the Module would be used as a second gain stage; they are "cascaded" together; the output from V1a is fed into (the grid) of V1b, and thus amplified further.. adding more distortion. V2a will still be unused.

OK, so once out of the Module, I am not 100% certain how it is done. I will guess that it hits the RM100 Master Volume (MV), and then the signal is fed to V2a. From here, it can go to the parallel effects loop, controlled by the Effects pot once returned for how much is blended. The Serial loop tho.. AFAIK, it is an "interrupt" type; IOW, so long as nothing is plugged into the Serial Effects send OR Return jacks, the circuit still flows.. right past those jacks. But, still thru "Amp V2a" and then back out via "Amp V2b." Thus, "Amp V2" is in path all the time.

Once out of "Amp V2," it is on to the Phase Inverter (PI), which is (apparently) a "long tailed" type. Basically (and simply and inaccurately for lack of space to fully explain), "Amp V3a and b" are each fed the signal, and each triode puts out the signal, but one side is "flipped phase" while the other is not. In the RM100, there are two tubes available per "side" of "Amp V3." IOW, "Amp V3a" will feed the two power tubes on the left, while "Amp V3b" will feed the two on the right. The "Amp Left Power Tubes" are in series, as are the "Amp Right Power Tubes." Pull the two outer or two inner, and the cicuit simply "skips" over the empty tube sockets.. ignores them. 60 times each second, one side will "push" the signal while other side "pulls" the signal. This is what is called an "Class AB" or "Push-Pull" type. It is very efficient for higher wattage output. A "Class A" circuit would simply amplify and be done. Without getting deeper, each has benefits, both in regard to power and harmonic content/alteration. And it does come down to taste!

So, that is it.. AFAIK at this point. I think it was Soulinsane who mapped it? Between posts by Soulinsane, Pete (Oskrat), and several others, the basics were there... then it was simply filling in blanks.

I really suggest grabbing, at the very least, The Guitar Amp Handbook.. by Dave Hunter. It does basic signal flow, what the components do, etc, and shows the inside of several popular amps' chassis, plus goes thru the idea behind them. IMO, any guitar payer who wants to understand just the basics, this is it. Even if you never work on an amp, at least understanding can help. Go further, and scour the 'net, grab Gerald Weber's books (DVD's too now I believe), which have "The Trainwreck Pages" in them. Ken Fischer (RIP) was a genius, and a natural when it came to amps. Trainwreck, along with Dumble, might be considered two of the most incredible amps out there, among many greats.

Sorry for the length! (and any mistakes)

 

[Julia]

Okay we'll continue the thread hijack.... sorry.... :lol:

My former (Mwhateveritwas) had a flow like this:

G = Guitar
(....) = bypassable stuff

G->V1->V2{preamp controls for the four channels and gain levels for the four channels}->V3a->(parallel loop)->V3b->(reverb)->V4{for remix} ->(serial loop)->V5 {PI} -> Master -> Power Tubes -> out to speakers

My 5150 II has:

G->V1->Switch Logic->{Lead or Rhythm}Pre-level ->V2->V3->Post level-> V4 {tube buffer} -> (effects loop) -> V5 -> V6 {PI} ->Tube Power {incl resonance & presence} -> out to speakers

So straighten me out if I'm not correct about the M100. It would seem logical the the MV would be after the effects loops. But is it before or after the PI??

G -> V1 -> Module -> (loop) -> V4 {PI} -> MV -> Power Section -> out to speakers?

or is it

G -> Module {with V1 and V2} -> (loop) -> V3 {PI} -> MV -> Power Section -> out to speakers?

Where the PI and MV can be in reverse positions?

Next I'll have to scour the forums.

 

[nikki-k]

Most MV are pre PI. I do not know of any large production amps that are post PI master (PPIMV; yes, can be confusing since Pre could also be a P ). Some boutique amps are. Arguements could last for years (and have) over even having a master volume, let alone deciding exactly where to place the "pollution." Effects loops are an easier debate IMO.. hehehehe..

With a post PI MV (PPIMV), the PI is slammed all the time. Well, not slammed all the time, but raise the Gain stage and the PI is hit progressively harder. With the MV before the PI (as is the case in most MV amps), ONLY when the actual amp "end volume" is desired to be *loud* will the PI be hit accordingly. This is where taste comes in, big time. One scenario: If one wants a decent amount of preamp gain, but does NOT want the PI hit that hard, yet still run the amp at a decent volume.. maybe the "sweet spot" would be about 6'ish were no MV present.. well, the PI is being hit like the amp is being run full-out, thus altering tonestack response and other tonal changes. Part of that "sweet spot" is how hard EVERYTHING is pushed. A master volume simply existing alters the tonality, response, etc.

With higher gain amps, the PI is simply not required for the amp to sound "balls out." In fact, some amps are so powerful in addition to 2-3 (or more) controllable gain stages BEFORE FX loops, PI, MV, etc is/are even hit, that the PI becomes a more subtle influence on tone, and the power tubes become less of an effect as well (yes, torch me for that one! I am simply saying that the preamp stage(s) are relied ona bit more for the heavy gain tone than the power section )

If one were to take an old Plexi 100 watt and throw a Master Volume into the circuit, it will alter the tonality. Placing it BEFORE the PI allows the preamp Gain stage to be pushed to the degree it would have taken FULL wide open volume settings to achieve; however! The PI would remain onyl pushed as hard as the MV before it would allow. Ditto for the power tubes. The tonestack could be pushed into full volume type changes as well. If the power tubes and PI do not get that full volume signal, they will not enter into distortion stages that are equated with that "dimed Plexi" sound.

Placing the MV post PI allows one more stage to be included in the "dime it!" part. Some will argue that the PI can have more influence on that "dimed" sound than the power tubes, and rightfully so in certain situations. Eliminate the MV completely, and NOW the power tubes come into full realization as seriously influencing tone.

ANY tube in a circuit will have influence to some extent. Every component will, as will any deviation from the simplest path. Types of resistor, cap, etc. But, it is those major points of consideration, IMO, that matter first.

Anyway! I would love to know what that (Mwhateveritwas) was. With alot of mod'd amps, anything is possible. It is off-the-shelf stuff that typically will be pre PI MV. Personally, I prefer both. I kept the PrePIMV on my Legacy, and added a PPIMV. I can control how hard everything is pushed right up to the PPIMV, and then use the PPIMV to control how hard the power tubes are pushed. If I did not dislike attenuators, I could then use one of those to act as a final volume control. Or, use a dummy load and a box to take speaker to line level out and feed that to a power amp, and amplify that "dimed Plexi" at a.. erm... "safe" volume

As far as the MV in the RM series... I have not tried it, but I would imagine that if the Return of the Series loop were used as an input (from, say, an RM4!), the main volume on that feed would have to control the level.. the RM100 MV would have no effect whatsoever. If I am correct, then it is a Pre-loop(s) MV. As far as Pre-PI MV... easy enough to tell from the sound put out. Have not tried anything to test the RM100... I am finding it is simply too heavy for me to deal with.

 

[JKD]

As far as the MV in the RM series... I have not tried it, but I would imagine that if the Return of the Series loop were used as an input (from, say, an RM4!), the main volume on that feed would have to control the level.. the RM100 MV would have no effect whatsoever. If I am correct, then it is a Pre-loop(s) MV. As far as Pre-PI MV... easy enough to tell from the sound put out. Have not tried anything to test the RM100... I am finding it is simply too heavy for me to deal with.

I'm learning and confirming a lot of things in this thread so thanks for that....

On the MV thing...I can tell you that the loop must be before the head MV or the MV is elsewhere in the circuit as the MV remains active when using the Series Return, at least on the RM50.

 

[nikki-k]

As far as the MV in the RM series... I have not tried it, but I would imagine that if the Return of the Series loop were used as an input (from, say, an RM4!), the main volume on that feed would have to control the level.. the RM100 MV would have no effect whatsoever. If I am correct, then it is a Pre-loop(s) MV. As far as Pre-PI MV... easy enough to tell from the sound put out. Have not tried anything to test the RM100... I am finding it is simply too heavy for me to deal with.

I'm learning and confirming a lot of things in this thread so thanks for that....

On the MV thing...I can tell you that the loop must be before the head MV or the MV is elsewhere in the circuit as the MV remains active when using the Series Return, at least on the RM50.

Ahhh!
Cool- resolves that! So the MV is post "Amp V2" and pre "Amp V3."

It is kinda cool, cause how an amp works can be explained without much (and I mean not much at all) electronic component understanding, or even theory. I would love to see a nice run through with an amp like the Marshall Plexi that almost anyone could read and then grasp the basics. Take that and then add a second bit about how adding this or that, removing this or that, and arriving at something like the JCM800 could occur. Wish I was more confident in my knowledge...

 

[Julia]

I've been using a Hot Plate. I use it primarily to protect my speakers (the cab is rated at 100W), and use it at most at -12 db so I can get a reasonable level of power tube saturation and get rid of the preamp fizzies. I find at higher attenuation the perceived tone changes too much, probably because of the Fletcher-Munson curves. That's where an equalizer comes in handy.

The Mwhateveritwas had the Master Volumes running at 75% and 60% with the channel volumes and gain regulating the output level in conjunction with the Hot Plate running at -8 to -12 db essentially using it almost like a non-master amp.

I can't run the 5150 like that. It's way way too loud. So the "Post" is at 4.5, and I'm guessing the MTS will be similar in that. Yet I can get some saturation, but not power distortion, and where can you get that these days without an attenuator on a 120W or 100W tube amp? Venues freak when you show up with anything bigger than a Epi Valve Jr., unless it's a biker club or an arena.

I don't have to worry too much about volume. Just so long as I keep it safe enough for my ears -- about as loud as an opened up 7' concert grand in a home having Prokofiev played on it. And my ears are shot anyway.

 

[nikki-k]

Yeah, "volume" is such an interesting thing. 50 watt head to a 100watt head (rated properly) is only (theoretically) 3dB louder. In operation, of course, it feels different, sounds different.. usually

When I played out, I could have used a 10 watt amp, if it got the sound I wanted. Heck- 1-5 watts is plenty. I preferred good sides and fronts. I do not know how I would do with in-ears, they came "after my time." hehehe!

Since full size heads (anything more than the 18, or some 30 watters) are impossible for me to cope with now physically, I am having to come to terms with an alternate solution. Sadly, it is for home recording, which kinda screams for them. The RM100 was the final straw in my realizing my limitations.

Oh! The 5150 was one amp I sooo wanted to like. My Legacy is another I have struggled with. Since the Legacy is nearly worthless on the market these days (Legacy II at NAMM), I think I will keep it as a "pet" and continue to play Dr Frankenstein with it

 

[Julia]

I hear you about lifting stuff and physical limitations. I have enough trouble with the 5150 head and a single Avatar 212 cabinet.

I got the 5150 because it was close enough to a sound I wanted, and unlike Mwhateveritwas, after you plug in your guitar and flip the standby switch it actually works. That's something very important.

 

[Zander]

I've been using a Hot Plate. I use it primarily to protect my speakers (the cab is rated at 100W), and use it at most at -12 db so I can get a reasonable level of power tube saturation...

I've been thinking about getting the Weber Mass. Have you had any experience with it?

 

[maximus1]

i now would say speakers and cabs contribute the most effect on overall sound with this amp, i just tried my buddy's vader 4x12 with my rm100 and it was night and day from my avatar with 2 k100's and 2 v30's . my cab was dark and had big time bass with smooth highs and the vader was all honky midrange, i would have had to add alot more bass and scoop some mids back to accomadate the vader. but at the same time i 've always thought my amp was kinda dark but now it seems my speaker choice may be alot of it. the vader eminence speakers seemed to have some midrange i need and my celestions seem to have the low end. with the size of the vader i thought it would have been bigger and deeper sounding but the eminence speakers must be alot different than the celestions in tone, something to consider anyway, makes me think my amps not so dark :shock: probablt swap my k100's for some eminence any suggestions?

 

[Julia]

Nikki, now that I re-read the thread...

Did you ever try the Shuguangs (EL34B-STR) in the amp?

 

[nikki-k]

Yeah- Ruby's. The EL34's just got too gritty for me. JJ 6L6GC calmed it down.. ran a pair for 50watts. And a Tung Sol or Brimar in V1.

 

[Julia]

Okay I'll say it -- I hated the EL34B-STR's. The tech put them in the JVM I used to have. I don't mind gritty but these were gritty/harsh.

 

[nikki-k]

Wow... must have been a bad batch, or something. I have a quad in my Legacy and they are great in it. The EL34L's are bit harsh for my tastes in the Legacy, and the 6L6GC's are nice as well. I have darker (and odd) tastes tho

 

[Shinozoku]

i now would say speakers and cabs contribute the most effect on overall sound with this amp, i just tried my buddy's vader 4x12 with my rm100 and it was night and day from my avatar with 2 k100's and 2 v30's . my cab was dark and had big time bass with smooth highs and the vader was all honky midrange, i would have had to add alot more bass and scoop some mids back to accomadate the vader. but at the same time i 've always thought my amp was kinda dark but now it seems my speaker choice may be alot of it. the vader eminence speakers seemed to have some midrange i need and my celestions seem to have the low end. with the size of the vader i thought it would have been bigger and deeper sounding but the eminence speakers must be alot different than the celestions in tone, something to consider anyway, makes me think my amps not so dark :shock: probablt swap my k100's for some eminence any suggestions?

On the subject of the Vader being bigger: It's to accommodate more low end if you want it, not to GIVE you more low end Also, if you want that added low end with the mids of the Legends, I'd replace the V30's first (basically, try both combos).

 

[Julia]

Wow... must have been a bad batch, or something. I have a quad in my Legacy and they are great in it. The EL34L's are bit harsh for my tastes in the Legacy, and the 6L6GC's are nice as well. I have darker (and odd) tastes tho

It might have been. I mean I did watch three matched quads arc before my eyes at the shop. :shock: The one I ended up with was the only one that worked of that batch and I hated the tone. To my ears anyway.

Qualification on the ears: I have had near total midrange loss in my right ear. The left ear is normal. The right ear compensated with highs and lows. So if I put a single ear plug in my right ear the sounds are kinda dead. If I put one in my left ear it sounds hollow. My right ear is a reverse Fletcher-Munson curve. :lol: I tend to forget this because I just live with it. Hearing aids won't help this -- it's the inner ear. And those of us with hearing problems think everyone hears this way.

I think I've got some odd tastes as well. :lol:

 

[decoys]

Funny to say, but i tried my RM100 with the Randall XL V30 Cab and the whole amp sound was way brighter than with my Mesa Recto V30 Cab ... strange also.