Technical explanation requested

[lenunez]

I've seen various posts here and elsewhere claiming the preference of using a boost pedal to hit the front end of a tube amp versus turning up the gain knob.

To me, it would appear that technically, the appraoches are pretty similar. They are both causing the pre-amp to run hotter. That said, the consensus that I generally see on this topic is that the pedal method is preferred.

To my ears, running a Bad Monkey into my Rocket 44 is the better method when I also engage the Bad Monkey EQ to fatten up the bottom end. With the Bad Monkey EQ flat, I don't really hear any other difference.

Does anyone have a technical explanation for what is different in these two approaches? i.e. What, if anything, is going on differently inside the amp?

 

[tunedown]

I've seen various posts here and elsewhere claiming the preference of using a boost pedal to hit the front end of a tube amp versus turning up the gain knob.

To me, it would appear that technically, the appraoches are pretty similar. They are both causing the pre-amp to run hotter. That said, the consensus that I generally see on this topic is that the pedal method is preferred.

To my ears, running a Bad Monkey into my Rocket 44 is the better method when I also engage the Bad Monkey EQ to fatten up the bottom end. With the Bad Monkey EQ flat, I don't really hear any other difference.

Does anyone have a technical explanation for what is different in these two approaches? i.e. What, if anything, is going on differently inside the amp?

I don't have your answer, but I DO have a couple of leading questions that may get us to an answer. I know there are a ton of really smart and experienced tech-heads on this board who can actually answer this question for you though...

I think the issue has to do with driving the first gain stage (specifically) and it also has to do with where the tone-stack is on your particular amplifier (before the pre-amp, after the pre-amp, etc). Some amplifiers have their tone adjustments before or after the pre-amp and this difference will change the way you get your best results with a boost pedal. I may have this backwards, but if your tone-stack is after the pre-amp you may not get as positive a result as if you put a boost pedal in front of an amplifier with the opposite configuration.

And I once heard somebody explain this by saying something about a boosted signal with a lower output impedance. But I'm no tech so it went in one ear and out the other. They also said it's the difference between increasing the gain AT the tube stage and boosting the signal BEFORE the pre-amp tubes. Because a Tube and a Transistor-thingie have different responses and dynamics and what-not and simply produce different results.

Hopefully I explained something wrong and a smart person will have to post to this thread and prove me wrong.

 

[fishyfishfish]

Thats pretty good. A booster also raises the total signal that is going into the amp much like a compressor, giving the preamp more to work with. there is also the blending of transistor square wave distortion, with the softer tube even order harmonics, making it sound somewhat closer to having the power tube distortion at lower volumes.