MKII and MKIII

[night-B]

I've seen a gut recently where the builder has put like 5 or 6 small caps on a rotary switch. Each one raises the capacitance of the output cap. Sounds like a good idea. I think it's in a D*a*m box, a Nth variant of the tonebender reissue.

[JakeFuzz]

[soundcloud]http://soundcloud.com/jakefuzz/mkii-revised[/soundcloud]

And 68n output cap wins. A little mud with the volume knob all the way up but smooth as butter. Now off to the for sale section to sell a MKIII 

[pryde]

 

Just awesome tone. I think the singing lead tones make up for any bit of muddiness at full volume. Good work indeed

[mgwhit]

I agree that one is the winner -- sounds fantastic!  I've put the parts for a Silicon NPN Mk II into a baggie to wait for my breadboard to clear off.  (I've heard it can compete with the Ge.)  Gotta try this.

[shawnee]

Man that sounds great Paul! Even better than the fuzz faces in my opinion. So what I am I going to do with these CV7112's now? 

[Mike B.]

Sounds great Paul. You got better sounds out of it than I ever did on that first demo, but it sounds fantastic after the cap change. I'll have to make a note of that if I ever build another one. Nice work indeed!

[JakeFuzz]

Just awesome tone. I think the singing lead tones make up for any bit of muddiness at full volume. Good work indeed

I totally agree, rolling down the volume knob gives me an incredibly useful overdrive sound and at full tilt I get a ridiculous lead tone.

I agree that one is the winner -- sounds fantastic!  I've put the parts for a Silicon NPN Mk II into a baggie to wait for my breadboard to clear off.  (I've heard it can compete with the Ge.)  Gotta try this.

Can't wait to hear it. I've never heard a Si tonebender (other than 'the fuzz'  ). I just tried some of Tim's 2n2925's in a fuzz face and it is the smoothest sounding Si FF I have heard yet. Could be good in a TB as well!

Man that sounds great Paul! Even better than the fuzz faces in my opinion. So what I am I going to do with these CV7112's now? 

Put them in a TB!  The CV's have a very unique natural warmth and harmonic quality to them. I think they would work well in a TB type circuit. You could probably get away with putting them in just one position with good results. This is an awesome pedal but I am still a FF fanboy for life, maybe I am too attached...

Sounds great Paul. You got better sounds out of it than I ever did on that first demo, but it sounds fantastic after the cap change. I'll have to make a note of that if I ever build another one. Nice work indeed!

Thanks Mike. Great build quality BTW. This has become one of my favorites. I noticed the small ceramic caps on the underside. Those go from collector to base? The old smoothing out trick? Did you notice a big change in sound when you put those in?

[Mike B.]

Thanks Paul. And yeah, those caps from C to B were to smooth out the high-end and some of the hiss. It worked pretty well. Before I added them, it was almost too much - especially with my Strat and AC15.

[timbo_93631]

Hey Paul, I picked up a MKII pcb a few weeks back.  Did you use the Solasound values in yours with the exception of the output cap?  I have been on the fence about whether to go the direction you did, or if I should go with the Marshall SupaFuzz values (10uf's  input and bypass caps instead of 5uf's) to achieve a bit more bass.
     Thanks!
          Tim

[JakeFuzz]

Hey Tim. You know I am not sure. The board is built to the guitarpcb mojo MKII specs. I don't know which model this corresponds to exactly.

http://www.guitarpcb.com/apps/webstore/products/show/2166316

There are also small smoothing caps from collector to base on all the transistors. Honestly though this circuit needs as much bass as it can get. With the higher output cap it does get a little muddy. I am not sure if adding more bass before saturation will cause it to get really flubbed out or not.

[timbo_93631]

Ah yeah, thanks for the link! That looks like a Solasound Tonebender MKII Professional with diode polarity protection, 4.7uf electros instead of 5uf, adjustable bias, and pulldown resistor on the input added on to me.  Other than those 4 things the component values are all MKII Professional spec.    I am gonna go the Marshall Supafuzz route which ditches the 10nf input cap, changes the 4.7uf/5uf electrolytics to 10uf, and subs 47k in for 100k on the collector of Q2.  I'll see where I need to go from there.  I am putting some Jazzmaster pickups in my partscaster this week (jazzcaster or twangmaster?), we'll have to see how that works with the rest of my pedals as well as this one.  Thanks Paul!

[mgwhit]

The Marshall Supafuzz doesn't just change the input cap from 5uF to 10uF -- it also changes the input resistor to ground from 100K to 10K.  The interesting thing about that is that it actually changes the corner frequency of the low-pass high-pass filter to a higher value.

5uF & 100K = 0.3Hz
10uF & 10K = 1.6Hz

To be fair, both of these values are stupid crazy low and there might be something else affecting the actual cut-off frequency, but I can't see much value in dropping from ~5uF to 10uF in that position.

(I've been using the schematics at Fuzz Central, which seem to jive with the GuitarPCB schematic other than modern touches, like the 1M drop down resistor and the bias trimmer.)

[timbo_93631]

Yeah forgot to mention the 100k to 10k change there.  I always find myself messing with the higher value tone control cap in MKIII's, I am sure I will end up trying a few values for the output cap here.  From the schematic I thought that was a high pass filter, cap before resistor, maybe I have it backwards?  Either way low E is ~80hz so it shouldn't make much difference yeah?

[mgwhit]

Yes, I misspoke -- it's a high-pass filter.  And that's what I was getting at.  Unless something else is changing the performance of that high-pass filter in a way that I don't understand a lower cap value isn't going to matter a hill of beans for guitar.  However, letting in lower frequencies could negatively affect the performance of the transistor, which is why I would be nervous about dropping that value in a way that would lower the corner frequency.

[timbo_93631]

I think this is getting into a pretty good thread Hijack at this point.   For sake of politeness lets discuss it in a new thread because I have some more questions about corner feq. and the affect it has on transistor performance.  Thanks!  Link to continuation of discussion: http://www.madbeanpedals.com/forum/index.php?topic=5623.0