Madbean Pasty Face (Soul Bender) - Increase Output Level

[Skreddy]

All makes sense thanks for the explanation Skreddy, i appreciate it.  

This is pretty much where i have left it at: I have replaced R8 with a 33k and left r13 as 10k which increased the output (as you explained).  The other improvement was increasing the tone 10k to ground with 33k, adding more bass makes it sound louder, but it helped. oh yeah, and removing that output r11.  All these things contributed to increasing the output slightly with each mod. Its pretty much at unity now.  Like i was saying before, depends on the pick up im using, but its all very close.  Could be my imagination too, but my leaky germs should up, stuck one in q3, leakage of 300ua, despite sounding different, i could swear its also a bit louder.  

Yeah so now im at around unity & the volume control is still pretty much totally redundant and stays on 100%.

Paul

You went the opposite direction on those resistor mods--that's even less volume than stock.  To increase the volume, you want a bigger resistor to the power supply and a smaller one to the transistor collector.

You should be able to get unity gain at about noon on that volume knob and a screaming boost at full up if you did it right...

What you want to do is lower R8 to 10k and increase R13 to 18k. 

[chromesphere]

I think we are looking at different schematics   the one im looking at is on the last page of the project file, right down the bottom.  Just to confirm, looking at that schematic and my build infront of me, i have increased R9 to 33k and lowered R8 to 10k.  Sorry i screwed up my description before.  Still cant get much over unity with the vol up 100%.
Paul

[Skreddy]

I think we are looking at different schematics   the one im looking at is on the last page of the project file, right down the bottom.  Just to confirm, looking at that schematic and my build infront of me, i have increased R9 to 33k and lowered R8 to 10k.  Sorry i screwed up my description before.  Still cant get much over unity with the vol up 100%.
Paul

Right; I was looking at the P2 schematic, not the P5 version.

Okay, so on this one, the resistor to -9v is R9 (10k stock value), and the resistor to Q3's collector is R8 (18k stock value).  This divider was put in place originally to provide a balance in volume between the high-passed signal (15n cap / 10k ground) and the full-range signal (100n cap).

R12 (1M to ground at output) is also redundant.  Shouldn't change the sound, but there's no need of it there since the volume pot is already providing a much smaller path to ground than 1M.

Okay, so you've changed the gain & bias at the collector of the transistor from 28k total to 43k total. 

Try this: leave your 33k at R9 where it is.  Jumper R8 so it's zero ohms between Q3's collector and the output.  You'll get maximum available volume and leave the bias & gain closer to stock too.  Unfortunately your tone control will get louder at the bassy side and quieter at the trebly side.  But this is the last bit of extra volume I can see getting out of this thing. 

I've modified an early FullTone Soul Bender (mid 90's version) for increased volume by just swapping the 10k and 18k and reducing the output series resistor to 18k instead of 47k (or whatever that particular one used).  Like I said, unity at noon, screaming boost at max volume.  So if jumpering R8 doesn't fix it for you, there's something else wrong either with your build or your components.

[chromesphere]

Hi Skreddy,

First up let me just say, i appreciate you taking the time to explain all this to me, you've been a great help (as with others that have responded to the thread), and i have learnt a bit about this circuit as well which is always good.

I think I may have found the problem though, and its got nothing to do with the effect board!  I decided to "press onward" and box it up last night.  First test, plug it in, power on, grab the guitar, slowly start increase the volume.  On about 1/4 volume, its already getting dam loud.  Way over unity on 1/4....I was going to box up the 2nd effect and see if i had the same outcome before i responded to this thread but just wanted to explain this before anyone else went to the trouble of responding, when it could just be a matter of a loose / dodgy connection on my test box!  Going to box up the 2nd one today, ill let you know if its the same outcome.  2 weeks of modding / fault diagnosing / harrasing the forum...and it could just be the test box...i hate life...

Now im off to punch the easter bunny.  Thanks again for everyones help.
Paul

[Skreddy]

Hi Skreddy,

First up let me just say, i appreciate you taking the time to explain all this to me, you've been a great help (as with others that have responded to the thread), and i have learnt a bit about this circuit as well which is always good.

I think I may have found the problem though, and its got nothing to do with the effect board!  I decided to "press onward" and box it up last night.  First test, plug it in, power on, grab the guitar, slowly start increase the volume.  On about 1/4 volume, its already getting dam loud.  Way over unity on 1/4....I was going to box up the 2nd effect and see if i had the same outcome before i responded to this thread but just wanted to explain this before anyone else went to the trouble of responding, when it could just be a matter of a loose / dodgy connection on my test box!  Going to box up the 2nd one today, ill let you know if its the same outcome.  2 weeks of modding / fault diagnosing / harrasing the forum...and it could just be the test box...i hate life...

Now im off to punch the easter bunny.  Thanks again for everyones help.
Paul

Very cool.  Change that 33k back to 18k, so Q3 will have its stock gain and bias.  It's set for a much higher gain now than it was designed.

[Skreddy]

duplicate post

[chromesphere]

yeah i was thinking that too actually, so i took your advice and took it one step further: returned everything to stock and it all works just fine.  Unity is a bit less then noon, heaps of room for boost after that....

Going to take apart the test box and put it back together...can only assume the problem lies with it and not with the effects boards.

Thanks agin for your help skreddy, i appreciate your time!

Paul

[chromesphere]

finished the 2nd soul bender and it works fine as well...

ok, so to sum up this nightmarish experience...

1) if your following the madbean DIY etch for the pastyface (soul bender) make sure you following the part values in the schematic and not on the BOM.

2) dont use a broken test box...?

They both work fine now, tonnes of volume with stock values.

Thanks everyone for your help.  Sorry to drag you all through this unlucky build

Paul