AMZ Mosfet Booster with BM Tone control?

[HeaD]

Hi, I would like to add a simple tone control like this...



...in this Mosfet Booster



Is this possible? How must it be connected? Thanks to all.

[HeaD]

someone? 

[vanhansen]

You should be able to put that right before the output cap (C4).

Another tone control option is the "Stupidly Wonderful Tone Control" from Mark Hammer.
http://img.photobucket.com/albums/v474/mhammer/SWTC.gif

[HeaD]

Wow, thanks vanhansen!!! 

[no one ever]

You should be able to put that right before the output cap (C4).

Another tone control option is the "Stupidly Wonderful Tone Control" from Mark Hammer.
http://img.photobucket.com/albums/v474/mhammer/SWTC.gif

ah geez. does it have to be before the output cap? i didn't factor that into my layout, which is etching today...

[vanhansen]

No problem, HeaD

no one ever, you might be able to get away with it working after the output cap.  I don't see why it wouldn't work, just going by common practice that I've seen on other circuits.

[ragtime8922]

No problem, HeaD

no one ever, you might be able to get away with it working after the output cap.  I don't see why it wouldn't work, just going by common practice that I've seen on other circuits.

If you are really worried about it and you've already etched then simply replace your output cap with a jumper and, assuming you are going to make a second board for your tone control circuit then just make the original output cap beome your new board's output cap. Or just don't solder anything in to the output cap slot (on your etched board) and "plug in" your tone circuit to the corresponding solder points.

[yalesmith]

Okay I preface this by saying I stink at reading Schematics (i am working on it) but graphical ( and by that I mean layout) how is this done?  do you connect one end of the capicitor (C4) to the one side of the pot and middle prong back to the PCB board?

[petemoore]

  Might want to check out what the tonestack loading is / compare it to the MB output impedance, consider a buffer [pre<tone control] if the TS loads throws off the eq-ing of the TMB knobs.

[yalesmith]

I am completely lost?

[petemoore]

  Impedance ratio.
  The output of X drives so much current, the input of Y 'loads' the signal as 'some current is used to drive the input.
  If the load is large [sorta low impedance like TC's can be] and the current driving the load is small [high impedance] losses can be expected in the signal transfer.
  "Not sure" is also what I am when calculating impedances, instead ballparking and whipping up a buffer if the load-match is deemed to probably require greater output drive.
  Don't know exactly what the impedance is of the MB output, nor the TC input, just looks like a good spot to suspect a possible mismatch.
  Adding the 4000pf to the .1uf creates a series .00047 / .1uf value, since in such cases where the large value is so much larger than the small value, the small value effectively [for what we'll hear or be able to detect] sets the capacitance of the two in series. Ie, in this case the .1uf is so much bigger that it can be ignored.
  If a buffer was to be needed, on a separate board, it'd be the 'third item' [MB, TC, Buffer] and should come before the TC to drive it.
  This leaves two possible orders of 'items':
  Buffer>TC>Boost
  Boost>Buffer>TC.
  I mention this since the MB is already high impedance input, buffer>MB might cause it to be very bright sounding, putting the TC between the Buffer and MB is worth a try, the buffer is/can be very low impedance, the MB is very high, this is the 'opposite' of lacking current to drive an input, could lead to harsh highs...I dunno, never tried it. 
 

[bwanasonic]

At the risk of sounding like a wise ass, do you want the Mosfet Boost, or do you want the BM tone control? As Pete points out, once you add the circuitry of the tone control, the properties of the MB kind of fly out the window. So it leads to the question, what are you trying to achieve?

K

[yalesmith]

okay I did not realize this, I thought Id be able add boost as well as some tone shaping.  It seems what you are saying I cannot have booth a boost and tone control with the amz design?  I always thought you could boost signal as well as filter some highs (tone control). 

[electrosonic]

The stock Mosfet Boost gives a boost across all audio frequencies. People like it because it does not color the sound much, it just boosts your signal.

The stock BM tone control gives a slight mid cut and like all passive tone controls there is an insertion loss.

If you tack a stock BM tone control on the end of a Mosfet Booster, you will be giving up the uncolored boost of the Mosfet Booster, and since you now have to make up for the insertion loss, you might not have the boost you were hoping for. You could add a follower between the booster and the tone stack to lessen the insertion loss, or add a gain stage after to make up the insertion loss. You could tweak the values of the BM tone control so it is flat in the 12 o'clock position so the booster has the option of being uncolored if you choose.


A.

[yalesmith]

i got you and this makes complete sense.......any ideas of how to do this?

[yalesmith]

Finally got back to doing this small project....i researched the BM tone control, spoke to Jack and now have it all setup and bam it does not work.  I think I know what the issue is and it has to do with the c4 cap. I understand that the tone control goes between c4 and R7 but what does that mean?  do I get rid of the c4 cap all together and the tone control goes where the c4 was?   

I assumed that the c4 cap stays and you just disconnect one end of it and that lead goes to the input of the tone control and you also disconnect one  end of r7 and that goes to the output of the tone control but i think i am so mistaken.,....i apologize for being such a dummy!

Thank and help is needed!

[Ben N]

R7?? What R7?

You need C4 to block the DC that's feeding the drain of your mosfet from spilling down your signal chain. The tone control wont do that, so no, you can't sub the tone circuit for that coupling cap.

[Mark Hammer]

i apologize for being such a dummy!

Nothing to apologize for.
The cap on the output of the MosFet booster is there to prevent any DC from affecting whatever comes after the booster.  Unless you plan to stick a cap after the tone circuit, it is best to place the tone circuit after that cap.

But the bigger question is what you want the booster to do for you.  I'm not so sure the BMP circuit is ideally suited to being a single-knob EQ for a booster.  It is intended to tame a fuzz which already has certain tone-shaping built in.  The MosFet booster is intended to provide very high input impedance, for preservation of existing highs, but doesn't add more than were there in the first place.  Given that, the BMP circuit may "work", but not necessarily in a pleasing or suitable way.

Someone suggested the SWTC, and that, or one of Jack Orman's very clever alternatives to it ( http://www.muzique.com/lab/swtc.htm ) may be more in line with what you want.

The thing about boosters is that, while full bandwidth and nice crisp highs is great for playing clean, it sucks for overdriving an amp, and yields a very brittle tone.  As a result, many such boosters come with a treble cut of some sort, or else a treble boost/cut (boost for playing clean and cut for overdriving).  That may be more in line with what you need.

[Ben N]

Just to follow up on ark's comment, here is a booster designed to sound good overdriving an amp input.