RM100: Low end problem?

[Rilke]

I've been trawling these forums in regards to a low end issue I seem to have with the RM100.
In short; it seems to be lacking the low-end 'thump', usually associated in chugs/palm mutes etc.
My observations stems from working in my recording studio, where I work full-time as recording engineer with +10 years experience (this is not to toot my horn or something but more as to establishing some precedence about where I come from).

My rm100 setup is at the moment;
Rm100 with MDA. Modules; Mamba SE, Chupacabra, Banned (the new Marshall module from Salvation). I've also had the S1S0 and the AngelE (both of which didn't have the ultra low end aswell).
Tubewise I've gone from 4xEL34 to 2xTAD EL34 STR + 2xGold Lion KT88.
Preamp tubewise I've been through a lot of combinations (just to eliminate that factor out of the equation aswell), atm I'm running a NOS Raytheon in V1, and quality tubes throughout the modules and the amp aswell.

Well on to the problem: In recording the RM100 I've noticed that I have a lot of difficulty establishing the thump of the low end, which is no problem when recording other high gain amps on the same cab (1982b with V30'es).
I've during last week recorded both a Marshall 410 and a ENGL Fireball, both of which seems to exhibit a beautiful low end thump, easily dialed in, which translated very well when recorded.

The Rm100 though doesn't do that thump, no matter how much knob-noodeling I do. The MDA upgrade means that the density knob is disabled (unless I push the knob which kinda meh's the amp). The Salvo Banned module come closest in this regard, but when compared to the 410 and ENGL I tracked this week, the low end problem becomes painfully obvious. I think the characteristics in the gain of the modules are beautiful, but the lack of a both tight and usable low end in the RM100 kinda annoys me a great deal.

What are the solutions, if any ? I've read about Pete's C3 input mod to the board, and also about MM tranny upgrade. But tbh I'm not ready to spring for the tranny upgrade if it doesn't deliver Does the foglifter do the thump better ?

Any opinions are welcome I've read that some here feels that the RM100 has a looot of low end, which just doesnt correlate with my observations and recordings of this amp, when compared to another highgain amp.

Best regards
Christian

 

[Mattfig]

Hiya....Sorry to hear you've been experiencing this issue with your amp....RM100 are powerful machines for sure and it sounds like you've got it dialed in and good tube choices as well as MDA...

Have you tried an EQ in the loop?

 

[Rilke]

Hi Matt!
I've experimented with an EQ in front which definitely help in regards to establishing usable low end (haven't tried it in the loop though, series loop I assume? Parallel is patched atm). Do you reckon that it might be the trick I've not caught on to?
With an eq in front the problem kinda persists, in regards to getting a defined and thumpy low end. IE I somehow have the feeling that the amp in itself just doesn't do ultra-'low'? From an engineering/mixing side of the perspective the ultra low, isn't always usable (oftentimes it's rolled of to some degree), but when I'm tracking growly downtuned guitars (C# and lower), the lack of the OMPH, which I can 'easily' find in other highgain amps, just bugs me

Do you have any of the same experience? I know you've been through all paces in regards to the RM100.

 

[Mattfig]

To be honest, I do use an EQ in the loop of all 4 of my RM100s...lol....

I've found it to be useful in helping each module speak a bit more clearly....I never use much, but a little in the series loop will go a long way!

Good luck!

 

[eyeball987]

I have had many stock, JF, Salvation, and other mods. And rolled 6L6's, 6CA7's, and EL34's through the power amp. For some reason, the JF mods have always had a bigger and tighter low end with more thump.

I do have the Foglifter installed and have settled with a Marshall 1960 cab with Greenbacks as my main cab, a Marshall V30 cab as a second, and EL34's in the power section. Bass on my modules rarely gets above 3 (9:00) and the Density sits just below noon.

The Mashall + was my favorite Salvation mod. It has something complex in the mids that I can't find anywhere else but it does not have that big tight low end that the JF Brahma has in my rig. Just the experience I have had with my ears.

 

[Capt_Tippy]

I don't have time to read all of this, but... get these tubes
http://www.thetubestore.com/Tubes/Preferred-Series/Preferred-Series-6L6GC
Bias them a tiny bit hot.
You'll have all the low end you can stand.

 

[withmittens]

I don't have time to read all of this, but... get these tubes
http://www.thetubestore.com/Tubes/Preferred-Series/Preferred-Series-6L6GC
Bias them a tiny bit hot.
You'll have all the low end you can stand.

thanks

 

[Rilke]

Matt: thanks alot! I'll give it a try and see if it doesnt do the trick, I really Hope so, cause atm this is my main issue with the Amp so far. but it's kinda a biggie since I would like the mts modules to do some heavy lifting for me tonewise, and this particular problem makes it hard to use in this application.

Eyeball, seems like you roll kinda the same kit as mine interesting about the Jf bass thing though. I have a Jf erect inbound atm so I'll get to hear also, I'm thinking that if a recto mod won't do IT, nothing will. Still curious to hear if any people have observed more bottom in the foglifter than the mda. Could be a relatively cheap Thing to try out.

 

[Rilke]

Capt tippy Thanks for the advice but do you in all honesty, think this is a tube related issue? I'm not ruling it out but the PA tubes I have installed atm are not exactly Minnie Mouse tubes. I'd hate to shell out more money in tubes if it only adresses the problem not at All or only 5- 10%. I could of course always use the 6l6'es in some other Amp. But biaswise and tubewise i've been through a couple of combinations already to No avail. Again thanks for the advice, Hope I'm not coming off as flippant or dismissive but my feeling is that if a good combo high grade PA tubes, which are already installed, doesn't do it, then the answer might not be in more tubes.

 

[Mattfig]

I'll add that tubes can add or take away across the EQ spectrum. One thing I've learned is that they all sound quite different and some combos that might add one characteristic, such as bass, will take away from elsewhere in the spectrum....Personally, I like small glass and don't go bigger than 6CA7s for most applications....

I have a few JF mods as well and it's kinda like tubes....Go with what has the best base tone and tweak it to your needs....I obviously prefer Salvation but appreciate Rob's approach as well....

You could also try a dreaded, toy, ridiculous, and I forget what else people have called it, BBE maximizer....Again, it's all to taste and whatever works for you....I prefer an EQ myself but some Sonic Maximizers can add some magic beef to your tone....

Good luck!

 

[eyeball987]

I have a few JF mods as well and it's kinda like tubes....Go with what has the best base tone and tweak it to your needs....I obviously prefer Salvation but appreciate Rob's approach as well....

That is why I have loved the modular concept for this long. There are so many options and flavors to please pretty much anyone and it is relatively easy to try so many of them.

Fig, you have helped me quite a bit over the years and it is much appreciated!

 

[Rilke]

Hi Matt, thanks again for the write up, might consider smaller glass for my needs (I could possible switch the TAD EL34's for a good set and see if it doesn't give more bottom). I'm still a bit reluctant to blaim the glass in this instance, as the KT88/EL34 on paper should yield plenty of low end.

Regaring JF/Salvation, my thread and responses is in no way meant to disregard Salvo's modules, they sound truly great, and in my opinion very close to the real deal (and I've recorded a fair share of those). But since they are the only modules I've tried I have no basis to form an opinion regarding low end in other modules in comparison.

I didn't have time to fool around with an eq in the loop today (busy recording other stuff), but I will definitely give it a go, ASAP, and give a writeup of my findings, if not for anything else, then for someone who stumbles upon this thread with a similar 'problem'

Thanks for the BBE suggestion, I've had my share of both good and bad luck with BBE's (mainly the latter heh), it kinda tends to convince you that you've dialed in a great guitartone ("really lifts the blanket" etc etc), when in reality it's just killed whatever mids you had, and took your highfreq's into some weird dimension from where they will never return. This is usually first realized during the mix-phase where those tones just don't gel very well.
Not to say it's not usable or sucky, but I've just messed up the tone with a pretty fair batting-average everytime I've tried to dial a tone with one, so I'll try and shy away from that path as long as possible

Does any have any luck/experience with Pete's C3 mod at the input point ?
Again thanks for the help and the suggestions, they're all very appreciated!

 

[JKD]

Are you unable to get the low end *recorded* or are you saying it doesn't have low end in the room? I wasn't 100% clear to me.

I've only ever reduced the value of Coupling at the input (reducing the low end.)

To me, a stock RM100 has an overwhelming amount of low end but somewhat muddy. The MDA mod cleans that up...even in the stock position, it is better than an unmodded RM100.

FYI - I've owned ENGL Powerball, SE, BM also....they do have a very tight low end but in front of a cab, with a mic...much less difference to the Randall.

 

[Capt_Tippy]

Capt tippy Thanks for the advice but do you in all honesty, think this is a tube related issue? I'm not ruling it out but the PA tubes I have installed atm are not exactly Minnie Mouse tubes. I'd hate to shell out more money in tubes if it only adresses the problem not at All or only 5- 10%. I could of course always use the 6l6'es in some other Amp. But biaswise and tubewise i've been through a couple of combinations already to No avail. Again thanks for the advice, Hope I'm not coming off as flippant or dismissive but my feeling is that if a good combo high grade PA tubes, which are already installed, doesn't do it, then the answer might not be in more tubes.

I dunno if it'll solve your problem, its just the 1st thing that came to my mind when I was reading the post. I use those tubes and they added a noticeable amount of low end when I 1st got them.

 

[Rilke]

JDK: Kinda both, i.e. I can't record it cause it isn't there.
With the ENGL Fireball for example (deep switch engaged, TS-808 in front), the low end, with bass at 1-3 O clock, is a thick, well defined PHOMHP on chugs, overwhelming and huge. It's easy to distinguish the bass notes, and it's defined in the bass-region. This is both in the live-room in front of the cab, and translates well into every mic I put in front of the cab. This might not be an optimal setting (too much bass, dependant on riff), but just to give an example.

If I take my Mamba as the opposite (Kill switch on or KS off but with a TS-808 in front, bass set very high, tight disabled, bottom switch set for the most 'bassy' response) i.e. the module set for the most bottom heavy behaviour, is a very different story. The bass-response sounds like it is set at higher freq, there is no real 'low' to speak of, both in the room and in recording. If I try to dial in more bass I experience exactly what you're describing; the bass becomes a mess and muddy, BUT the bass still strikes me as lacking real 'deep' bass, frequency-wise it behaves as if the bass is high-passed always.
This is my experience of the cab-behaviour in the room aswell. The same goes for the Chupacabra (unless bass is set exceptionally high, which leads back to the muddy bass again), the S1S0, The AngelE. The Marshall Banned module I have can grab that low chug, as the only one, but somehow not convincingly.

My experience with a 5150 and a (albeit short experience) of working with a Framus Cobra, is that the 5150, while not being a bottom heavy amp, exhibits more deep end, and the Framus exceptionally much so.

The modules grains out the same type of gain as the amps, and are indeed very convincing tonewise in all other regards, but maybe I'm just chasing something a) only in my mind or b) not achieveable on my rig, either due to me not doing it right, or the rig boundaries in it-self.

Cpt Tippy: Hmm, sounds interesting, I might just go for it; worst case is that I can use the 6l6'es in another amp if they don't just do the trick for me in the rm100. I'm really getting to be trigger happy on new PA tubes, if that does it, I'd be eternally grateful

Generally speaking, I hope I'm not coming across as if I'm losing my mind and I'm trying to turn guitar into a bass like a maniac I honestly do think the module-way is the bee's knees, but the lack of defined and 'true' bass response out of the RM100 is just whats keeping me at a 85% there feeling atm. Anyway thanks for keeping me company in my ramblings and all the helpful suggestions, what a great forum!

 

[JKD]

Stuff like that can drive you crazy, I doubt you are crazy...would be interesting to see the spectrum of both amps.

Having own enough ENGLs and Dual Rec type amps, I know what you mean about them....I just haven't experienced any lack of low end in teh room here but then I'm not really looking for it either. For all I know it's a factor of the design / transformers whatever.

The only way to know for sure if your amp is acting up would be to try someone else amp though :-/

 

[Mattfig]

Just thought I'd chime in once more and remove my suggestion of BBE or the like....Most suck pretty bad since you can't put that magical low end where you need it....But, I will add, if you can find an Aphex with Big Bottom, they play REALLY nicely with RM100s....I have two Aphex C2 units for this reason...

If you get an EQ (which is an easier and more direct option), just be sure it can run at line level....

Cheers and best luck,
Mattfig

 

[Rilke]

JKD! Exactly!! It's exactly stuff like that which can drive you crazy (trying to find low range, which maybe isn't needed anyway haha). During the last recording I checked the response of the RM100 vs an earlier recorded Dual rec with a PAZ analyser (same cab), which seemed to suggest that a Dual rec ("unfair" comparison I know considering the low-end in that particular amp) had a lot more info going on in the 60-150 region than the RM100 through the Mamba module. This is of course so unscientific that it's laughable but it kinda leads me to the thought that the RM100 just rolls off at a higher EQ point.

When looking at the amp specs (particularly the coupling capacitors), the RM100 has a higher value input CC than the Rec, which should suggest that the RM100 should be dark. Of course the Rec is build dark as a mofo and along different design specs than the RM100, so the 1:1 comparison isn't at all valid in this case, but the RM100 should (on paper, and listening to other peoples experience) be dark. I stumbled upon an article regarding the KH100 that they changed value on the coupling capacitor near the power amp to make it even darker voiced (which suggests a higher value there).

So my thoughts atm are that my RM100 might at some point in history perhaps have undergone a capacitor change (I'm a recent owner of the amp so I have no idea of it's history), perhaps towards brigter cap values.

As you say it might just aswell be a design factor which isn't really easily fixable.

And yes, the only way to know for sure would be having another RM100 in the room and A/B'ing (live in Denmark and my RM100 seems almost to be the only one I can see in the vicinity).

Atm my thoughts are to bring it by my amp-tech and have him check it through and through, and consult him on a change of CC-values at some point in case he can't find anything wrong.

Mattfig! Cheers, totally forgotten the line level thing thank you! You might have saved a couple of bucks and headaches there Aphex C2 units aren't really up for grabs around here (again Denmark :/ ), but I might go grab one.

Anyway, I think my next step is to check with a line level EQ in the series loop (see what happens), but also grab the head and hand it off to the amp tech, and see if he finds something. I've had it by him earlier in an unrelated repair, so don't think he went through it there.

Could be brillant if it was something wrong with the head and I've started this whole thread because of a broken amp. Somehow crossing fingers that this is the case (in that case I sincerely apologize for this novel), but if it's not, then a CC change/mod might give me my lacking lows.

Lastly if have a Erect mod incoming so depending on the low's in that mod, my problem might reside in the C3 in the preamp modules, instead of the amp in itself.

 

[iekobrid]

Have you tried running the RM-100's preamp signal out into a different head or power amp, to try to identify where the issue really lies?

 

[Rilke]

Alright! Back at it again!
I've just tried (pr Matt's suggestion) running an EQ in the series loop (had to dust off an old TC G major unit to find something that runs line lvl). And lo' and behold, there was the low end. I found that with a 3-4 db boost, relatively small Q, set somewhere along the lines of 90-130, the thump of the amp comes through, and matches favorably up to other to thump of other highgain amps.

I would imagine that this is obtainable with a capacitor change somewhere along the line aswell (have contacted the amp guy regarding this and waiting to hear his suggestions), so I won't have to run an effect just for the thump, but I can testify that this does indeed make the amp much more pleasing in regards to establishing the thump.

I must admit that I can't rule out that this is just a problem in my amp (which may have been modded at an earlier point to become tighter unbeknownst to me) but if you have a low-end problem, a line level EQ unit does indeed fix up the bottom end.

I'll prolly update this thread once more, once I've heard back from the amp tech regarding possible mods within the head itself, as I could imagine that it might be of interest to others who feel that the amp lacks a bit in the sub-low department.
Anyway thanks for all the helpful comments!