Is a Clean Boost pedal with gain, vol, treb and bass controls still a clean boost pedal ?

Telejester

If i was going to buy a clean boost pedal it would have 1 single control knob to boost the signal going into my amp and that is it. I see a multitude of pedals labelled clean boost that have vol, gain, treb and bass controls and i think to myself nope thats an overdrive pedal. Anybody else believe a true boost pedal has a single control knob like the cae mc401 is designed ? I think the mc401 sounds terrific, with its single control it gives the front end of an amp a huge boot up the arse,  but I also think the mc402 which has a drive side also sounds pretty poor.

ChrisCox1994

The mojohand speakeasy I think is still a clean boost as the gain doesnt really distort into a clean amp, it just compresses and rounds off the tone a bit more.

Compared to what its based on (an EP Preamp type circuit) i'd say its far more like that than a Tubescreamer or something. 

It was tone, gain, volume and a mode switch but still does variations on the EP preamp style boost - a "drive" pedal it is not.

Gassage

Suggest it's an EQ by then

ICBM

I would say it's a clean boost if it doesn't introduce any clipping itself - since clipping is the 'guitar definition' of distortion. So even if it has a gain control, if you're setting it so it's still clean then it's still a clean boost.

Quite a lot of pedals which just have a single volume knob aren't clean in the strictest sense either - especially not when turned up all the way - and often have an EQ curve even though you can't adjust it.

My experience is that most players don't actually like a *truly* clean boost because it sounds bland. Hence why there are so many - if they were all actually clean and did nothing but make the signal louder then there wouldn't be any point in different ones...

57Deluxe

The Kokko Booster is - hardly colours your tone even when fully dimed. Most excellent  AND VERY LOUD PEDAL

Collings

Yes for me a clean boost is one that increases the input signal without adding any overdrive distortion. I quite like to have some eq to tweek 

Dave_Mc

I think it depends on what it does and what the circuit is- something like the Xotic AC and RC Boosts to me are more overdrives, because the circuit is basically an overdrive (clipping diodes in the feedback loop of the op-amp). (Though of course, as ICBM says, if you keep the gain low enough that it's not clipping, it's still arguably a clean boost- e.g. klon, timmy, and the RC boost.)

But something like the newest version of the MI Audio Boost n Buff... I'd say it's more of a clean boost. Far as I'm aware, the circuit is still (more or less) the same as the original one with no gain control, just now you can adjust the amount of grit you get from the transistor.

So basically I agree with what @ICBM says (as usual), just with that little added caveat. I'd still consider the ones with a more "overdrive pedal" circuit to be low gain overdrives, but admittedly you're probably kind of getting into semantics...

ICBM

I should also probably qualify what I said earlier too, in that if you have to keep the gain control down at say 9 o'clock to prevent any clipping in a diode circuit then it isn't *really* a clean boost… it's an overdrive being used as a boost. On the other hand if it doesn't clip until it's just turned up so far that the output clips, then it probably is even if it does! If that makes any kind of sense .

So as usual it's a bit about the circuit design and a bit about how you use it.

Dave_Mc

^ Yeah pretty much.

I have the Mooer clone of the RC Boost, and you do have to turn the gain well up to get any grit (and even then, it's subtle). I might be misremembering, but I think it has 3 diodes going each way in the feedback loop, so I guess that explains how little grit there is. Though I'm guessing that grit is from the diodes... but I could be wrong. Seems like a waste of time putting 6 diodes there if it's not.

But something like a klon (again, got the cheapo soul food klone ) starts to clip under 12 o'clock I think.

But it actually does sound like a genuinely clean boost when the drive control is at zero. (In a blind test you can't tell whether it's on or off at unity gain.)

So yeah.

ICBM

Dave_Mc said:

I have the Mooer clone of the RC Boost, and you do have to turn the gain well up to get any grit (and even then, it's subtle). I might be misremembering, but I think it has 3 diodes going each way in the feedback loop, so I guess that explains how little grit there is. Though I'm guessing that grit is from the diodes... but I could be wrong. Seems like a waste of time putting 6 diodes there if it's not.  

They may actually be there to stop a chip or a transistor going into saturation and sounding bad (or latching-up to the supply voltage, in the case of a chip - which in the worst case can blow it) rather than to cause overdrive.

That's what the 'clipping diodes' in the Blackstar HT pedals/amps are for, as we've mentioned before. They're actually to prevent the valve going into blocking distortion, which sounds terrible - not to create the overdrive, which is already occurring in the valve well before that. Pairs of diodes are commonly used in many circuits to limit maximum voltage swing, in fact.

JayGee

Sounds more like a use case than a piece of hardware to me...

Dave_Mc

ICBM said:

Dave_Mc said:

I have the Mooer clone of the RC Boost, and you do have to turn the gain well up to get any grit (and even then, it's subtle). I might be misremembering, but I think it has 3 diodes going each way in the feedback loop, so I guess that explains how little grit there is. Though I'm guessing that grit is from the diodes... but I could be wrong. Seems like a waste of time putting 6 diodes there if it's not.  

They may actually be there to stop a chip or a transistor going into saturation and sounding bad (or latching-up to the supply voltage, in the case of a chip - which in the worst case can blow it) rather than to cause overdrive.

That's what the 'clipping diodes' in the Blackstar HT pedals/amps are for, as we've mentioned before. They're actually to prevent the valve going into blocking distortion, which sounds terrible - not to create the overdrive, which is already occurring in the valve well before that. Pairs of diodes are commonly used in many circuits to limit maximum voltage swing, in fact.

Yeah.

I think this is starting to get beyond my pay grade

But seriously, though, I suppose that could be it. I don't suppose you could tell from the schematic?

http://forum.musikding.de/cpg/albums/userpics/17486/xotic-ac-rc-booster_schematic_v2~0.png

(Grr I can't seem to successfully get the pic to attach, you'll have to click the link )

I'm assuming that's correct. I thought it was on freestompboxes, but it wasn't, so I had to google it...

EDIT: I think that schematic is labelled backwards- I think the AC ("Almost Clean") Boost has the 3 diodes in asymmetric clipping configuration and the RC ("Really Clean") Boost has the 6 diodes. So the schematic, I think, is for the RC Boost, which is the one I'm talking about.

Which also makes me think they're for the clipping- the AC Boost (which I haven't tried) has quite a bit more gain and fewer diodes, which should result in more clipping- right? As I said, I'm getting beyond my (limited) knowledge very quickly.

ICBM

Yes, they are there for clipping I think. All the distortion in the circuit comes from the first IC stage as far as I can tell, and the level going into the tone control chip will be heavily limited by the filter components so it won't be in danger of being driven too hard.

I didn't know before what the AC and RC stood for, and I could never remember which was which in terms of overdrive, so I have now learned something useful .

lukedlb

Isn't an EQ just a fancy boost?

Dave_Mc

ICBM said:

Yes, they are there for clipping I think. All the distortion in the circuit comes from the first IC stage as far as I can tell, and the level going into the tone control chip will be heavily limited by the filter components so it won't be in danger of being driven too hard.

I didn't know before what the AC and RC stood for, and I could never remember which was which in terms of overdrive, so I have now learned something useful .

Thanks

And haha, it's not like I'm an Xotic afficionado (so I hope I've told you correctly what the "AC" and "RC" stand for ), I've never tried any of the "real" ones, as there are no dealers here. I've just got the cheapo Mooer version of the RC Boost (which is pretty nice).

EDIT: Huh, the schematic pic seems to be working now.