Mark Hammer's "The Crank" sound clips?

[shredgd]

Hi,

I want to build a non-Jfet booster, and I found interesting info about The Crank. Unfotunately I could only find one sample (http://www.diystompboxes.com/smfforum/index.php?topic=46145.0), so does anyone know where to find others?
Thank you,

Giulio

[shredgd]

Anyone?

[Mark Hammer]

Not likely.  And the reason is that it doesn't really HAVE a sound of its own, any more than the MXR Micro Amp, AMZ MosFET booster or Klon Centaur do.  Well, let me retract that.  They all have an effect on the sound, but what you would have plugging your guitar into any one of them and into a soundcard is completely separate from what you would have plugging the pedal into an amp of your choosing and mic'ing the outcome.  And of course, at that point, it's more about the amp than the pedal, isn't it?

It's a decent booster that produces clean and slightly dirty-ish sounds.  If you want the sound of a pedal that has a modest overdrive sound, without a midrange hump (hmm, wonder what pedal he's talking about? ), then something like the Blue Magic may be more in your league.   If you need clean clean clean at all settings, it's not your first choice either.  At highest gain, though, it trims a bit of treble back and adds a bit of grit so that the distortion generated from the amp is a little more pleasing than if you fed it a super-hot signal with far too much treble.  There is enough output from the Crank that it can tolerate insertion of an SWTC for those who need just a bit more treble taming when pushing an amp into clipping.  Depending on how hard it is for you to score a dual-ganged 10k pot, you may want to consider something else.

[shredgd]

Thank you for your reply.

I am actually looking for a booster (for solos, not to use as "always on") to replace my AMZ Mosfet Booster.

The latter does exactly the flat (in terms of frequency response) and clean boost, but I've realized this can be a little too "hard" to my ears, because of the well-known effect of apparent increase in bass and highs when volume is increased. Also, its cleanliness doesn't help when playing solos with a clean sound, because it doesn't have any compression/limiting effect and peaks are often unpleasant for me and for the audience.

Lately, I've been using an SD-1 (with gain at min and level at max, of course) as a booster, and I realized a little midrange hump is what I'm after, together with a little limiting effect. However the SD-1 is maybe a little too much in both senses. Also, I want to build my new booster in the same box with a delay, to put at the end of the pedal chain, in place of the SD-1 (I don't have the space for both, and I also would like to eliminate the SD-1 because it is the only non-true bypass pedal I have at the moment).

You might say "build yourself a compressor and use it as a booster, then!", but I want the booster circuit to be small, otherwise it won't fit into the delay box...

So, if someone has suggestions on what circuit to build, you're welcome!...

Giulio

[Mark Hammer]

This is an excellent reply, and clearly specifies your needs.  Thank you! 

What may be suitable for you is a sort of adapted TS circuit.  Adapted how?  First, soften up the clipping by putting a resistor between the diode pair in the feedback loop and the inverting input.  Try 10k for starters, though you may want to increase it depending on whether you like what you hear or not.  This is a standard arrangement used to soften the clipping effect of diodes.  It will have a few additional effects.  One is to reduce the amount of added harmonic content.  Another is to reduce the compression introduced by harder clipping and offer more output level. 

Second, open up the low end by increasing the .047uf cap to ground (from the inverting pin) to .22 or .47uf.  the smaller-value cap is there to prevent the lower notes from generating too much clipping.  Of course, if you reduce the degree of clipping available, then that becomes less of an issue, so you have the luxury of letting more of that bass through.

Third, drop the value of that .22uf cap after the 1k resistor to maybe .047uf.  That will raise the default treble rolloff higher.  Between the extended bass and raised treble, the mid-peakiness will be reduced considerably.

Fourth, drop the Gain pot down to 250k or even 100k, and raise the feedback resistor in the tone stage from 1k to 4k7 or even 10k for more output.  This will shift where some of the gain occurs from the clipping stage to after the clipping stage.  So, still plenty of output, but the diodes aren't pushed quite so hard.  remember that gain is multiplicative (just like it is in the Crank), so even though max gain is reduced in stage 1, even small changes in stage 1 gain make stage 2 gain "show up".  Easier to dial in gradations of mild grit that way.

At that point, I think you are well-advised to consult the document on Jack Orman's page about re-jigging the TS9 tone control, such that you can get the sort of tonal adjustment that meets your needs.

Note that this will not likely result in a sound that resembles a Tube Screamer.  What it does do is use the TS as a kind of "platform" from which one can construct a desired sound.  My gut sense is that this will move you closer in the direction of what you said you need: a wee bit of grind, a teeny bit of compression, a small mid-hump placed in the midts of fairly "normal" bandwidth without so much top end that things sound brittle, and enough level boost to do damage.  The fact that one can use an existing TS9 board to accomplish this is a plus.

[m-theory]

Yes, some TS derivitive might be the ticket.  LPB-1 might work for you as well. 

[Caferacernoc]

You could alter the Mosfet boost if you want too. Change C1 to a smaller value for less bass. And then, after C4 add Led diodes to ground for a little mild clipping. Put a really small cap in pararell with the diodes to roll off some treble. Season to taste.

[shredgd]

Thank you so much for all the interesting replies!

I think I'll probably give the LPB-1 a shot first, as it is so easy and fast to build. In case it will disappoint me, I will start the more experimental TS-derivative road...!

Giulio

[Mark Hammer]

A solid strategy.  Even if it does not do what you are aiming for here, an LPB-1 unit will provide utility in the long run.  I can pretty much promise that at some point in the future you will need to bring a low-level signal like a mic up to a higher level, and the LPB-1 (originally intended for that very purpose!) will be there for you.

[shredgd]

Today I kinda breadboarded a LPB (actually I grabbed some scavenged components I had and soldered them point-to-point without any board... turned out as a 3D circuit!) and compared it with the "mini-booster half" of an old Sweet Thing circuit I had in my bin of unused components and circuits.

Unfortunately, I couldn't quickly compare the dry tone with the boosted tone of any of the two, because everything was connected on the fly with "crocodile" wires. However, I can say they're both to consider as "clean boosts", at least until you set the volume pot fairly high (but at that point the volume boost is really too big for me, and it is difficult to say if the distortion comes from the booster itself or from the saturated input stage of the amp).
This comparison confirmed to me that I don't like jfets that much: it is probably due to their very high input impedence, which increases the presence of my guitar tone in a too much "hi-fi" way. In the past, I already did a comparison between jfets and bipolar tansistors when I was looking for a buffer, and the bipolar won greatly, so that now I have a (switchable  ) bipolar buffer at the beginning of my pedalboard.

Even if it is a fairly clean boost, I think I will give the LPB a try in my pedalboard and see how it behaves when playing live (home-made experiments are always just for screening). If I still feel there's too much added brightness in my solos, I might add a 1n cap or something around that from signal to ground*, and I might reduce the input cap value if bass feels too pronounced. Regarding volume peaks, I might simply remember to turn on my RossDyna compressor when playing the intro of Sweet Home Chicago or Soul Man...! 

I will keep you updated.

Giulio

* by the way, in case I need that, where do you suggest to put it: at the beginning or at the end of the circuit?

[shredgd]

Hi,

I finally finished my 2in1 delay+booster pedal and I'm very happy with the results. I put the LPB as booster, while the delay is a Danelectro PB&J delay, with improved input and output buffers (copied from the Ibanez AD-80) and modded for true-bypass.

The LPB behaved very well live, so that I think I will settle on that, instead of looking elsewhere (see above for details). It keeps a balanced response when used for solos, way better than the Mosfet boost I had before, which excessively incresed bass and presence. I like it as it is, with no need for mods (again, see above).

One weird thing I noticed, though, is that both my BSIAB2 and my Shredmaster (but not my Tubescreamer) behave oddly when I engage both the delay and the booster, that is: when I engage the booster, I have the expected volume boost; if I add the delay, I get a further volume boost!  I obviously get no boost over my distorted tones if I only engage the delay.
I think this must be due to some impedence factors, but I have no clue on this.

Did any of you ever experience something similar (maybe with a pedal different from a delay)?

Giulio