Back by popular demand - The Brick - with Clips

[DougH]

http://www.aronnelson.com/gallery/v/DougH/Brick/

[brett]

Hi
What a cool schematic.  Took a minute or two to work it out.  I'm thinking that it's gonna be a bit like the Jordan Bosstone on steriods.  Maybe??
(I can't see any link to the clips.  Are they missing, or is my employer filtering them?)

[ambulancevoice]

frequency trippler yes?

[Mark Hammer]

Nice tone.  Nice clips.  Gotta love that stutter effect.   Has some nice sponginess to it.  Pray tell, what might I reasonably sub for a 2N404?

[Simon Owen]

I built the hamronic perculator with a utility buffer in front of it. Swapped transistors til I settled on a AC127 and 2n3906.  If also added a switch to switch in the perculator so I could have a clean boost and Octave pedal in one.

[DougH]

The stutter effect is just me twiddling the pickup selector. It really has nothing to do with the Brick. I figured since I had all the feedback going I'd have some fun.

The transistors and diodes are pretty hard to find, unfortunately. Jason Munoz sent me the transistors in the mail a few years ago when we were on here trying to figure out the Perc. I stumbled on the 1n46's surplus and liked them so I used them (and sent some to Jason too, haha ). They behave similarly to 1n34a's (sound similar in this shunt clipper configuration) but have double the threshold voltage. So this gave me a hotter output and allowed it to drive the amp harder. I've spoken to Perc owners and read reviews where many are disappointed by the near-unity-gain of it. That's what happens when you shunt Ge diodes across the output...

If I was going to start from scratch on something like this today, in all honesty I'd start with Tim E.'s "Harmonic Jerkulator". With the current production Si bjt's and the biasing he worked out, you will have a consistent and stable platform to tweak from. I haven't tried it yet but a lot of people like it. (Hmm... I should give it a shot on the breadboard sometime and see how it compares...)

Thanks for the comments. I tried this with my new amp a couple nights ago so I thought I'd stick a mic in front of it last night. I was just screwing around. The "tune" clip is something I did 3-4 yrs ago when I first posted the schem.  With Aron's gallery, I finally have a permanent home for this stuff, since I hate web page maintenance.

I'm going to be recording more of my stuff that I've built over the years and sticking it up there. Film at eleven...

[DougH]

FYI:

Video of Albini demo-ing the HP and a "clone":

http://www.gearwire.com/bp1-albini-comparison.html

Compare this to the BrickFuzz or BrickMayhem clips for fun.

[PerroGrande]

Any particular characteristics to look for in the 2N404? 

[John Lyons]

Sounds good Doug! The Voxish amp sounds good as well from the short (pre brick engaged) intro.
When you get to the clips of just the amp I'd be interested in checking them out.
Curious to hear the clean and overdriven tones.

John

[Ed G.]

Whoa!
That sounds like fun! I loved the funky "brick tune" and it had some great rhythm and lead tones, of course, some tasty playing also.

[jakenold]

Hey Doug,

Great design and tasty clips as always!

About the diodes, wouldn't stacking two in series give them a turn on voltage similar to that of the diode you are using here? I like how you are making it like I am making my fuzzfaces - I neglect the fuzz-pot and configure it to turn it all the way up, and then I use a pot at the input, like Fuller does. This makes for a better gain control imho. But sometimes the other is better, now I think about it... 

Kind regards, Jake

[DougH]

Any particular characteristics to look for in the 2N404?

I couldn't tell you, in all honesty.  IIRC, the hfe of this one was 60.

When you get to the clips of just the amp I'd be interested in checking them out.
Curious to hear the clean and overdriven tones.

That's what I'm going to work on next, John. That and some new clips of the Octal Fatness with the KT77 and new schem, etc. Thanks!

Whoa!
That sounds like fun! I loved the funky "brick tune" and it had some great rhythm and lead tones, of course, some tasty playing also.

Thanks Ed! I did that clip a few years ago and lost track of it somehow.

About the diodes, wouldn't stacking two in series give them a turn on voltage similar to that of the diode you are using here? I like how you are making it like I am making my fuzzfaces - I neglect the fuzz-pot and configure it to turn it all the way up, and then I use a pot at the input, like Fuller does. This makes for a better gain control imho.

I think I tried stacking the 1n34a's like that but it didn't quite sound the same. It's worth a try though.

Re. the input fuzz control, I was just following the Percolator schematic that Alf had posted a few years ago. Thanks for the interest!

[PerroGrande]

Thanks, DougH.  I happen to have a boatload of 2N404's, so I'm going to breadboard one of these up.   I didn't know if it was touchy to leakage, Hfe, etc.  I'll report back here what I find re: transistor characteristics.

[stopstopsmile]

Harmonic Jerk is not even close sounding doug. Nice clips.  I would love to see your take on the harmonic jerk.  Breadboard that bitch up!

[Gus]

Doug this is the first time I looked close at the schematic of the brick.

Clever two gain stages kind of running at about 1/2 or so the 9volt supply
The 47uf at the emitters looks to be very important to reduce AC interacting of the stages
and the collector currents are kind of forced to be close to  equal being in series.
  Lowering the voltage to each stage lowers the max available gain of each stage maybe more about just the right amount of gain in each stage.

interesting double gain stage.

The 47uf at both emitters make an AC ground and kind of isolate the AC part of the stages.  Q2 bias is the collector to base 220K
Q1 is the 680K

Have you made the bottom a Si PNP with a different  bias resistor value?
Maybe something like a TIP30? and adjust the C to B for the same voltage at the two emitters.

Looks like it is Cool how the parts interact changing one bias resistor

What do you set the voltages at
  top collector
two emitters
bottom  collector.

That 47uf limits the AC interaction between the two transistors.  What happens with a series resistor to make the AC ground more "soft" and allow the two gain stages to interact more by shifting the operating currents around?.

[DougH]

Gus, the Brick is just a Harmonic Percolator tweak. I don't remember much about voltages and etc, but I know this circuit has been analyzed to death here on the forum over the years. The DC circuit is a vertical stack a la a mu amp or something, which makes the biasing weird and sensitive to transistor type. The AC circuit is just 2 cascaded gain stages. Alf's original reversed Perc schematics are drawn horizontally and you can see the AC signal flow much easier.

I have not experimented with it much. I built this 3-4 years ago and am just documenting it in Aron's gallery. Thought I'd do some up to date clips too, so people could get a better idea what it sounds like.