The Poweramp

James Freeman

Rock Star
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3,318
Class AB, Class D, Tube, SS.
Impedance Curve.
Real volume vs modeler settings.
Why Master on 2 (or lower)?


This is the place to discuss poweramps used with real cabs, and why they are the last frontier (imo) of accuracy in modelers.

In my experience, feeding Helix Preamp models into the FX Return of my tube amp with a standard SLO100 Long-Tail PI Poweramp topology, makes the sound and feel indistinguishable form the real tube preamp.
Can I say the same when using a small Class D digital poweramp feeding a Full Amp model?
Yes I can get very close but I have to lower the Master on the helix model way down to 1 to get the equivalent 'voltage' on the virtual PI to sound the same.

Share your experience and gear, and let's discuss this.
 
Another piece of information that doesn't translate directly to modelers is dual master volume amps.
Modelers typically model only ONE of the volumes and bypass (on 10) the other.

Friedman BE100 Deluxe, has a Channel and a Global volume, that's two Log pots that attenuate the volume.
Mesa Boogie Rectifier has Master volume per channel and global Output volume, that's also two log pots one after the other.
Diezel VH4.
Marshall JVM410
etc.

Some math to translate it to your modeler (assuming all volume pots are logarithmic).
Let's say you have both the Channel and Master at 5 (12:00 o'clock), that's 10% output voltage after each pot.
Thus: 10%*10% = 1%, and 1% the voltage will be around 1 (8 o'clock) on a single Master volume amp Like JCM800 or SLO100.


potentiometer_taper.jpg




A quick test to hear when the modeled poweramp in a Full Amp model starts to compress/distort is to set Treble and Presence on 10 and slowly raise Master from 0 up until you hear a change in sound, typically around 2 with Helix models.
Mind that on a real single master volume amp like a SLO100, 2 (9 o'clock) is already inhumanly loud.

Now you know where my suggested setting of "Master on 1" comes from, it is the equivalent of dual master volume amp on 5 and 5, which is super loud even in a club.
 
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I don’t have much to add other than I greatly miss my black Carvin rack mount T100 stereo power amp loaded with 5881’s. It was tweaked to perfection for me by a tech at Musicmakers off of Lamar in Austin. It was built like a tank. Stolen from a storage shed during a move.

:(
 
This subject is one that I approach with (even less) science than every other topic I form an opinion on. This is my take.

In a traditional guitar amp; I tend to favor 6l6 based power sections over el34 generally speaking. With modeling; I find I prefer el34s just a bit more. I don't want insane amounts of coloration or exaggerated hype (Katana and Orange Pedal Baby have entered the chat) I have to go through a stack of mental gymnastics to work around and dial out. As I say this; I DO enjoy the Quilter stuff quite a bit at quiet to jam room volumes. Then it starts getting into a zone where you really need to adjust the tone stack and the control set is strange and not really friendly for doing this on most of their models.
 
While I haven't tried it in a long time, I've really disliked any modeler (FM3, Stomp) into the effects return of my Electra Dyne. Sounded muffled and weird and just made me want to play the actual amp (although I didn't spend a lot of time tweaking it). And, if I'm going to bring a big tube head somwhere, I'm going to use it as the amp it is, and the modeller only for effects.

I have actually really enjoyed my Stomp into the Power Amp In on my Katana 100 MkII head with a Lone Star 2x12. Albeit this was at home at “loud TV levels“ and not band volume. Going to try the same with the FM Turbo when it gets here later this week. :). If I like it enough, I may pick up the PowerStage 700 and try it…
 
My experience with the helix and both tube heads (always marshall) class d power amps into 2x12 or 4x12s has been good.

I always use full models (non master volume amps most of the times) and usually I need to add some more low/low mids in order to get the right kick from the cab, specially with my SS power amp (Seymour Duncan). Anything else sounds fine.

I prefer what I get form a the tube power section compared a solid state one but latter is good enough.

At higher volumes there's something about how tube power amps and speakers work together, I believe, that makes the experience a bit more fun. Might my brain playing tricks to me too. Don't know.
 
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I play modelers specifically to get the sound of a non-master volume amp played loudly at whatever volume I care to play at. So mostly, I put Master on 10.

I spend a lot of my time on tweed Princeton model with Master on 10 and drive anywhere from 4 to 7.5. At any of those settings, the "real amp" would be loud enough to cause damage to my hearing playing daily in my 12'x12' music room. Which is why I don't play the real amp and instead use a rig that costs quite a bit more than the real amp.

As for finding an actual Poweramp to drive my cabinet that "sounds exactly like the tube amp I'm trying to emulate" that's a fools errand. As I noted above, I am not playing at anywhere near the spl of the real amp, so it is never going to sound or feel exactly like the "real amp".

I've tried effects returns of tube amps and a whole host of solid state amps from cheap chip amps, to quality ICE amps, to modestly priced bass amps, to enormous early 00's era class AB PA amps excepting the cheap ones with insufficient headroom, they all sound a bit different, but none so far has been so superior that sound wound up being the most important deciding factor. The beastly Crown PA amp made the most sense because it was stereo, but it's fan was also kinda loud. I have a Samson Servo 120a incoming - cheap, stereo, seemingly plenty of headroom, and designed to be very quiet with no fan, etc. I will start a thread on it once I've had time to test it out against my Seymour Duncan Power stage 170.
 
While I haven't tried it in a long time, I've really disliked any modeler (FM3, Stomp) into the effects return of my Electra Dyne. Sounded muffled and weird and just made me want to play the actual amp (although I didn't spend a lot of time tweaking it). And, if I'm going to bring a big tube head somwhere, I'm going to use it as the amp it is, and the modeller only for effects.

So much this for me, with my Helix, although I think (HX) modeling in general is not for me, because I haven't found a model that is "perfect" for me yet, and it didn't get any better into an FX return of amps. It just doesn't sound right.
 
So power amps, some people say crank it’s volume and then use the preamps volume as a channel volume, while others do the opposite.

What is y’all’s preference?
 
Not much to add or say that I only use a pair of "FRFR" headrush 108 , to go the route of 2 amps and cabs would be way beyond my means so i stick to this, although i may upgrade my "FRFR" to maybe a pair Yamaha DBR10 or QSC
 
If using a "real poweramp" and trying to get the particular sounds of it, why wouldn't you just use the preamp version of the models?
 
Not much to add or say that I only use a pair of "FRFR" headrush 108 , to go the route of 2 amps and cabs would be way beyond my means so i stick to this, although i may upgrade my "FRFR" to maybe a pair Yamaha DBR10 or QSC
If you have any diy ability at all, there is no reason two cabs and a stereo Poweramp should be wildly more costly than two HR108s.
If using a "real poweramp" and trying to get the particular sounds of it, why wouldn't you just use the preamp version of the models?
Because then you would have to use "the real Poweramp" and turn it up to "real Poweramp" volume levels.
 
For a while I want a little crazy, creating preamps blocks/drives out of marshals and Bogner’s, on AxeFX etc.
 
I play modelers specifically to get the sound of a non-master volume amp played loudly at whatever volume I care to play at. So mostly, I put Master on 10.

I spend a lot of my time on tweed Princeton model with Master on 10 and drive anywhere from 4 to 7.5. At any of those settings, the "real amp" would be loud enough to cause damage to my hearing playing daily in my 12'x12' music room. Which is why I don't play the real amp and instead use a rig that costs quite a bit more than the real amp.

As for finding an actual Poweramp to drive my cabinet that "sounds exactly like the tube amp I'm trying to emulate" that's a fools errand. As I noted above, I am not playing at anywhere near the spl of the real amp, so it is never going to sound or feel exactly like the "real amp".

I've tried effects returns of tube amps and a whole host of solid state amps from cheap chip amps, to quality ICE amps, to modestly priced bass amps, to enormous early 00's era class AB PA amps excepting the cheap ones with insufficient headroom, they all sound a bit different, but none so far has been so superior that sound wound up being the most important deciding factor. The beastly Crown PA amp made the most sense because it was stereo, but it's fan was also kinda loud. I have a Samson Servo 120a incoming - cheap, stereo, seemingly plenty of headroom, and designed to be very quiet with no fan, etc. I will start a thread on it once I've had time to test it out against my Seymour Duncan Power stage 170.
I had a Sampson 120... pretty anemic (55w per channel 8ohm) and doesn't work well with stage monitors. Would probably be ok for unpowered near field studio monitors which is what I think it's designed for.
 
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