The truth about absolutely neutral and linear boosters

“We’ve all been there: playing that perfect song, 16 bars before the solo, in love with the sound, 8 bars before the solo, still in love with that sound, preparing the foot to hit the booster pedal so that everyone can hear you solo with that incredible tone. Your 40 seconds of fame start now! Unfortunately the sound isn’t louder, but rather muddy and undefined, or the top-end is harsh and you’ve lost all the depth in the low frequencies. So what happened? While you’ve landed here, reading this blog entry, others have gone to a forum to write: “My current boost pedal lacks transparency! I need an absolutely clean linear boost, which doesn’t add or suck highs and just increases the volume for my solo!“.

The replies are mostly the same: “Use the ultra linear YXZ!“, “Pedal ZXY is the best clean one!“, “TS9 is the way to go!“, “You need a volume pedal!“ and “I use an equaliser! IMHO the best!“. Believe me – I see these posts all the time and you probably have as well. So, who is right? Nobody? Everyone? Unfortunately there’s no answer to satisfy the poor guy… I think he’s simply asking the wrong question. Ok, ok, ok, … lets sort this out and consider the topic in all its aspects.

There are 3 points: -technical aspects, -signal interaction of the gear used, -hearing and listening habits

“Technical aspects sounds boring!“
Yes, absolutely. We want to make music, right? But what if I told you that if you had an absolutely clean & linear boost, you probably wouldn’t like using it with a valve amp? It isn’t hard to build something like that, but it won’t be the ultimate weapon for every amplifier or for every situation. Depending on your amplifier and the gear you are using, there’d be a high chance the sound would be harsh in the highs or muddy in the low end. Why? This has something to do with the architecture of your valve guitar amp and the behaviour of the valves. Virtually no guitar amps have a linear frequency response and depending on the amplitude of the incoming signal, the amp’s signal is more or less distorted but never linear. So perhaps we should reconsider the term “linear boost“. I’ll give you an example:

“Damaged eggs don’t sound fine!“
Imagine you have a bucket. This is your amplifier. I give you a few eggs, which are your signal. You put the eggs in the bucket, which is now half-full. You put the lid on the bucket. Perfect. You want a louder signal? You want a boost? No problem. I give you a few more eggs and you put them carefully into the bucket. Still fine, no eggs are damaged, although the bucket is full to the brim. The lid only just fits, but you again want more boost. You remove the lid, I give you more eggs and you press the lid onto the bucket so it closes. You can imagine what just happened. The result is that a few eggs are damaged or broken. Your amplifier is distorting, because it can’t process the signal anymore in the way you wanted it to. Imagine you have a high gain amp and it’s already feeding-back. What you actually have is a bucket full of scrambled eggs and now you put more eggs in it. Good luck with that! Do you remember the start of this post? The scenario where you tried to boost the sound of the solo? You had put too many eggs in a bucket which was already full. That’s what happened. The result was damaged eggs. And damaged eggs usually don’t sound good. Which brings me to the next topic: interaction.
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• 25 April 2025
• Freedom, Music, Varia
• Boost, Booster, Engineering, guitar, Joki Schaller, JULIAN, Lehle, Stuff for Nerds, Sunday Driver, SUNDAY DRIVER SW, valves