LPB1 Clone way to loud

[talktomrgibson]

hi there,

i am pretty new to building stompboxes but loving what i'm learning from experimenting and reading.

i have built a modified LPB1 clone with a BC549 chip from my local electronics store. i love the tone of the pedal when its fully wound out but its simply way to loud...(unusable in a live environment unless its on all the time).

is there any way i can reduce the overall volume of the effect ? i have a A100K pot on the output, but i want to keep this at maximum as it cleans up the signal too much when i reduce it.

basically i want it to be exactly the same but the overall volume lower....

is this trying to get to much out of a 'boost' style pedal, and should i be leaning towards more of an overdrive design?

thanks for any advice/help you can give

Nic

[~arph]

Well,

It sounds like you need to turn your amp down. The overdrive you get is not coming from the LPB-1 but from the overdriven preamp in your amp.
So yeah, either reduce volume at the amp.  Or build an overdrive circuit.

[GibsonGM]

Hey Talk,   good 'side effect' you've noticed.  What kind of amp are you using?   Often times, I find that running something wide open makes my (tube) amp HOT!  And I love it.  Trouble is, you get the issue you're experiencing.  Far too loud, and turning anything at all down makes it 'flat' again.

No amp is capable of doing it all....what you're probably seeing here is that you're feeding a high level to your amp, which *naturally* distorts since it's far above the expected input signal.  Especially nice in a tube amp (think about how Van Halen got *that tone*...WFO marshall with boosters, etc).    And many times, it sounds awesome!! But loud!  The physics of the speakers/cab come into play then, as does power amp distortion, depending on what you've got.

So yes, I think you might do well to find more of an overdrive-type design to mess around with, unless you want to play with the emitter resistor (the 200 ohm, you can increase it) to calm the LPB down.   I use things like an LPB to boost volume for solos (because, with a 40W tube amp, I have headroom....the volume will go way up, but the tone stays nearly the same. Fender amps are pretty clean and good for that).   For me at least, it's about getting the tone you want, and then boosting THAT for solos.  So things are consistent, one gig to the next at different volumes.

Maybe check out some of the overdrive 'clones' around here?  I don't use OD, I go more for distortions....TS-9 or 808 are great 'middle of the road' pedals to start from.   It's very hard to get a nice 'brown tone' with things NOT fully cranked, tho....but keep working into it, you will find a combination that gets you close!

Hope that helps!  

[talktomrgibson]

problem with reducing the amp volume is i can then never turn the pedal off as it will be to quiet.

i figured it might be the overdriven preamp, only option i realy see is to run this pedal on its own amp, if i wanted it blasting out at 100% volume.

it just sounds so nice that i was kinda hoping to be able to get the same tone out just softer

thanks GibsonGM too, sounds like you completely understand where I'm coming from haha, in a studio this thing would be awesome.
i'm currently using a Hayden MOFO 30W (amazing) and a Vox AC15, i'll have a play with the 200ohm resistor, but might end up having to experiment with some overdrive circuits too

thanks guys

[mistahead]

What has been said already is spot on, unless you run the boost wide open your tubes aren't clipping a nice drive.

Check out also the 5th Gear OD and maybe one of the Electra variations, both simple but effective ways of getting a reasonable clip.

[~arph]

Btw, the sheer volume may also be part of why it sounds so good.

[Mark Hammer]

Do yourself a favour and switch from a 100k volume pot to a 50K SWTC tone control ( http://hammer.ampage.org/files/SWTC.gif ) and a 50k volume pot.  The tone control and new pot value will behave like a 100k pot that can never be turned up more than halfway.  That will solve your too-loud problem.  But equally important, being able to trim back on some of the treble makes it a more useful booster.  Jack Orman has a nice page where he takes the basic SWTC idea and extends it.  http://www.muzique.com/lab/swtc.htm

Generally speaking, if one is going to push an amp into overdrive, via a booster, you want to cut back on the treble a bit, such that the amp generates harmonics of the fundamental, rather than also generating harmonics of harmonics.  In general, it is just a smoother-sounding overdrive if one tames the top before pushing the amp.  What I have suggested here will let you do that, while solving your too-much issue at the same time.

[talktomrgibson]

Do yourself a favour and switch from a 100k volume pot to a 50K SWTC tone control ( http://hammer.ampage.org/files/SWTC.gif ) and a 50k volume pot.  The tone control and new pot value will behave like a 100k pot that can never be turned up more than halfway.  That will solve your too-loud problem.  But equally important, being able to trim back on some of the treble makes it a more useful booster.  Jack Orman has a nice page where he takes the basic SWTC idea and extends it.  http://www.muzique.com/lab/swtc.htm

Generally speaking, if one is going to push an amp into overdrive, via a booster, you want to cut back on the treble a bit, such that the amp generates harmonics of the fundamental, rather than also generating harmonics of harmonics.  In general, it is just a smoother-sounding overdrive if one tames the top before pushing the amp.  What I have suggested here will let you do that, while solving your too-much issue at the same time.

that sounds fun Mark, im going to give it a try and picked up some 50k pots today (a B50K for the tone and A50K for volume)....can you tell me if i'm getting this right, the resistor before P1 (the tone pot) dictates at what frequency the rolloff begins, and the cap value dictates the range of the rolloff?

what values do you suggest for the resistor and cap? i was thinking of starting with a 1k resistor and a 18nf cap. i think i have some .002 ones laying around too.

[GibsonGM]

1/(2pi)*R*C gives you your rolloff.    Add in the resistance to the left of the pot wiper, and that = R.     You can use a 'center half-power frequency' point by using HALF the total resistance as a value.

With 1K and an 18nF cap, plus a 50K pot, you'll be down 3dB between about 156Hz and 6kHz as you rotate the pot.  Might want that 6kHz to be higher, but it's up to you....

Best way to tweak the SWTC is, to me, by ear - using Mark's values in the gif as a good starting place (that will put you in the right "guitar area" and you can tweak a little from there if you want to). 

[Mark Hammer]

It's only a 6db/oct rolloff, so there's no real need to raise it above 6khz.  Plenty of treble will still get through.

Myself, I think that ALL clean boosters intended to occasionally push an amp or other pedal into overdrive should come with a treble-cut control.  Even though the Klon Centaur came with a boost/cut treble control, in discussions with Bill Finnegan, it was clear he viewed the boost function as largely superfluous, and the cut part as far more important.

If the simple booster circuit is intended to accomplish a number of other functions/goals, like:

• bring a weaker signal up to some desired level (e.g., when feeding a voice mic to a guitar amp)
• matching levels between several sources
• providing a high input impedance for impedance matching purposes
• optimizing S/N ratio

...then full bandwidth is a good thing to retain.  But if the express purpose is to extract more harmonic distortion out of a subsequent stage, trimming the harmonic content you feed that subsequent stage is generally a good thing.

And just so the calculations don't turn out wonky, the formula is 1 / [2*pi*R*C]  As my stats software nags me about every day, bracket location IS important! 

[pinkjimiphoton]

OR experiment with switchable input caps, say .1 .22 .47 caps and by putting bigger capacitance  you can make much more break up in the circuit itself so you can get some distortion to enhance your sound with the master volume on it down some... still drive the amp, still get that "on 11" "edge" but at a lower volume. use smaller caps if you want to make it brighter.

sometimes making one of these fuzz is a really great sound if ya dial it in right. if it already sounds great, try adding in caps in parallel til you can balance it out well. on mine, i have each cap on  a pole of a tptt switch and their free ends connected together. you can dial it in to whatever combination you like best, and get more beef and distortion with each click of the switch.
on an original one, you could probably wire it to the on/pff switch and add input jack switching.

just an idea.