Which knobs control Power amp and Which knobs control Output

briand

How can I figure this out for the different amp models.

panthemusicalgoat

Good question. I've wondered too but here's my take. Pre obviously controls power and on amps that have a master and and volume I'd say the master is the post amp (meaning it adds tube gain) and volume is just simple digital dB control (no gain unless you use the tape 1,2 limiting which add saturation instead of standard or none which just do basic limiting compression). Appearently tape 1 is analoge artifacts (gain) and tape 2 is straightforward saturation. Kind of a musical taste thing

Make sense?

briand

what is the tape 1,2 limiter?

briand

so the 18 Special for example. It has only a gain knob and a volume knob.

now following my idea of how a real marshall works the gain knob is preamp and the vol knob is power amp gain. Meaning if i really want the best crunch i am going to need to take the power amp into consideration. or am i way off here?

pipelineaudio

In a real amp, if you do want power tube distortion, you'd want that master volume (or equivalent) knob up as well, and have to deal with attenuation of the actual SPL somewhere down the chain (or sticking the cabinet in an isolated room). For Peavey, older models had "pre" as preamp gain and "post" as master volume. But what seems to be hinted at here is gain of two different preamp-ish gain stages.

If you have two preamp tubes in series, changing the gain on the first one can have a very different effect than changing the gain on the second one. For the brief time that Harman had Bogner designing things, they had a Q&A at digitech and also a very similar speech from Mesa Boogie, and I have read a few discussions with Rupert Neve and George Massenburg speaking about the same subject. As soon as the signal goes non-linear, effects like compression are not additive as you would think for dynamic range devices (people often don't think of preamp tubes in a guitar amp this way, but even the term "saturation" should cue you in) from one stage to the next, but multiplicative!

If there's enough gain on the first "tube" or stage, you probably won't notice too much more waveshaping distortion on the second one, but you will notice much more compression, much much more

briand

oh ok so the pre and post both affect the preamp section of the amp. like dual gain stages. that makes more sense to me now.

so on the ou821 the lead channel has two gain stages and the Volume knob is actually a master volume knob. I just right now noticed the entire "Resonance, Presence and Vol" Section is labeled Master so hence Master Volume duh.

So that master vol knob is going to affect power amp modeling? or yonac doesnt do power amp modeling and its just a db level

briand

this case study actually makes me start to think if the best use is a bias amp model inside of the tonestack app. Perhaps the ability to recreate the power amp sim in bias makes the model more accurate?

panthemusicalgoat

Tape 1 is (saturated) limiting with analoge artifacts (sounds more dirty/natural), tape 2 is saturated limiting with a cleaner modern digital algorithm and standard is digital (no distortion saturation) limiting.

That's according to the creators so it's not just my opinion.

I'd say if you want things to get crunchy when you clip use tape 1 or 2. Its a personal taste thing

briand

i doint understand what you mean by tape 1 and 2

briand

ohhh tape 1 and tape 2 in the output limiting options in Audio Prefs?

panthemusicalgoat

Yes exactly. Ive noticed the tape limiting adds a warmer effect to amps when they clip