Everybody knows that boosters are a great way to squeeze more gain out of amps and decent drive pedals. It is indeed a great use of boosters and one I practiced for years with great success. I find this to work particularly well with #Marshall and #Vox style tube amps, or any amp that breaks up as nicely as these do. Another less common use of boosters is to act as a volume booster after gain pedals and into a clean high-headroom amp, so you can get the same amount of gain, only louder.
But there is more boosters can do for you than just "more gain". They can actually help you squeeze more sparkly clean tones out of your dirty amp and in a way give you more headroom, which will increase your dynamic range and make your rig more versatile in an instant. To explain the sensation in one short sentence, to those who have experience pairing Marshalls and Les Pauls, I was able to play crystal clear tones using a 1996 Les Paul Standard loaded with PAF style humbuckers plugged into a Marshall JCM 2000 DSL 401 through a booster. That same guitar has been rocking that same amp for over 12 years and never before sounded like that... I was no less than shocked!
My Recipe
Ingredients
1. One Marshall JCM 2000 DSL 401 EL84 based tube amp. I believe most English Marshall tube amps will produce similar results. I added English because I had several bad experiences with other tube Marshalls, but that doesn't mean they are all bad or anything like that.
2. One Seymour Duncan Pickup Booster pedal. What's really important here I think is the quality of the audio circuit and the fact that it has a flat frequency response and a full range.
3. One Les Paul Standard or any other guitar, except maybe one with active pickups (although I haven't tried any)
Instructions
Connect the guitar to the Marshall's clean channel through the booster. Set the Marshall master volume to 12 o'clock (half way). That's just where the power amp stops farting and starts sounding great. Set the gain on the channel as low as is required to get clean tones out of that guitar. On my Marshall that's around nine o'clock and it sounds dull, dark and horrible. Now set your boost to its minimum gain setting and turn it on. Play and increase the gain on the pedal until you are happy with the sound.
Bonus: after you find the sweet spot, play with your guitar volume and you will find more useable crystal clear sounds that you didn't know your rig is capable of.
On my booster 6db is the minimum gain, so I have never tried anything below that, but I can imagine that depending on your amp, having more gain range can help you match the pedal to the amp and guitar. However, the clean sounds I'm able to get out of that Marshall are nothing short of unbelievable to me! I have tried that trick with my Les Paul, #Duesenberg Startplayer TV, G&L Legacy HB Strat and Fender Telecaster. In all cases the results were phenomenal. With the Strat and Tele I can get clean tones with or without the booster, but with it they just shine so bright and clear that it don't make sense to play clean without it anymore.
I don't know the science behind that magic, but I think it's all related to what is called gain staging. I would imagine that the booster in that case operates as another gain stage before the first preamp tube and somehow turning down the gain on the tube and turning up the gain on the pedal creates that effect - I don't care why at this point - I just want to play!
Conclusion
I don't see why that trick won't work on any tube amp that lacks clean headroom. On Fender style amps you probably don't need that trick for that purpose, but on most other amps you want to at least try it, if clean sound it something you wish you had more of.
A part of the little trick I shared here, I think the takeaway is that you need to experiment with your existing equipment a lot to get the most out of it. I play for many years and one thing I learned is that as long as you don't use crappy gear, the most important thing is how you set up and play your rig and not what brand it is, or how expensive it is. A simple tube amp with a little boost pedal can sound like 10 different amps that are 2 times more expensive if you just know how to set it up and where to push it.
Now go play!