Conrad Buzztone and Volume Expander

[anders]

A cousin to Fuzzrites and Orpheums...



I went NPN, 2N2222 for Q1 and MP38 (hfe 45) for Q2 and I omitted the 27k resistor to increase output.

[Beaker]

Helvete Anders!!! Never heard of this beast before - many thanks for doing this.

This thing is pure, utter, velcro ripping filth, and I love it. Someone call Mirosol 'cos this one is right up his street.

Like you, I converted it to NPN (don't forget to turn the electrolytic around), used 2N2222 for Q1, and a MP38 for Q2. I used a Russian D311 Germanium diode, and 100k linear for Fuzz and 100K log for volume. I agree - leave out the 27k - it drops the volume too much.

It's fatter sounding than a Fuzzrite - more like a Univox SQ-150. I'll have a play around with it, but this will be getting boxed.



If you read this, and you like gnarly 60's Garage Punk fuzz, BUILD THIS NOW!

[boratto]

yeahhhh, looks amazing==> build list.

[Travis]

2N2613 is PNP germanium. I feel like I'm missing something here

[Beaker]

Yes, you are right. All we did was "flip" it to use NPN transistors - you just need to reverse the polarity on the electrolytic cap. Job done!

This gets dangerously close to the Flaming Lips "Hit to death in the future head" and "Transmissions from the Satellite heart" rythmn guitar tones.

[Travis]

I understand, I was more referring to the part in the layout that says "2N2613 or other low gain PNP silicon". 2N2613 isn't silicon. The circuit should obviously work with silicon but I would imagine it would sound pretty different than the original if the original is using 2N2613

Your description has me interested anyway.. I love the Flaming Lips! Their fuzz tones are mesmerizing

[rocket88]

I think what's he's saying is that the layout says low gain Si, while the actual transitor mentioned in the original is actually Ge. So, wouldn't it be better to sub it for a low gain Ge rather then low gain Si, the PNP or NPN is irrelevant. Know what I mean beaker? In any event, I'll be building this soon, after building the FR-69 I need more nasty 60's garage/psych effects. Only problem with most of them is they're inherently trebley and nasaly, which doesn't translate well to bass. Btw, nice job with the layout.

[adapt]

ha, my friend has an original one of these. it sounds so nasty, i love it

[anders]

Hehe, I'm glad you like it. As for the the 2N2613 transistor, several sources on the web states it as a Ge but I prefered to follow the schematic: http://www.freestompboxes.org/viewtopic.php?f=19&t=6685&hilit=conrad&start=20.
Tried a Ge in Q1 as well but I prefered a silicon in there.

[Beaker]

"So, wouldn't it be better to sub it for a low gain Ge rather then low gain Si, the PNP or NPN is irrelevant. Know what I mean beaker?"

Oh yeah, I see what you mean - sorry I rather glossed over that part.

So yes, I'm sure it will sound different, but as built it sounds pretty damn good. I'm going to have a play around with it, and see what happens. Will keep you posted.

[Beaker]

Right then, I have been having a mess around for an hour with this, and as I suspected, the transistor choice is not that important - I tried silicons and germs in both positions. My favourites for Q1 are ME4003 and 2N2222, but I like the 2N2222 better - produces less sustain, so adding to the velcro ripping effect. MP38 is perfect for Q2.

What is more impotant is the diode choice - I tried a bunch of different silicon and germanium ones.
Silicon diodes make it smoother, but more generic sounding - nothing I haven't heard before. The D311 I went with first gives a great rasping, ripsaw sound - as I say, very Flaming Lips. D9K diodes make it smoother - more buzzsaw, and no diode at all makes it sound like you have torn a speaker cone.

All these three options are great, and very different to each other, so I'm going to put them on a on/on/on switch, for D9k, D311 and no diode selection options.

This one is definately getting boxed up :)

[anders]

Cool!. I'll play around with the diodes as well, didn't know they had such a big impact of the sound. Right now I have a SFD-112 in there but I will try a bunch of others now.
Tack!

[Beaker]

Du er velkommen :)

[rocket88]

That sounds fan-freaking-tastic beaker. Great job on the investigating on the circuit. That's pretty interesting that Q1 doesn't matter of it's Si or Ge, I wonder then if the reason for it being Ge is due to when it was built/designed and not having Si around or being really expensive. Did you happen to try an Si transistor in Q2? If that actually changes the sound it might be neat to put the transistors on a switch so you can change the effect even more then just having the diode on a switch. This has been added to my build list, I need some more ripping 60's fuzzes.

Btw, I hope you don't think I was calling you out before buddy.

[Beaker]

Yeah, I tried both Si/Si and Ge/Ge combinations for Q1 and Q2 - I even tried Ge for Q1 and Si for Q2, but as Anders pointed out it sounds best with Si for Q1 and Ge for Q2.

As to why it sounds best like this - I really don't have a clue. My only hunch is that the gain is more important than what the transistor is made of. Lower gain Ge for Q1 just destroyed it - just made it sound like bad dirty boost type of pedal.


"Btw, I hope you don't think I was calling you out before buddy."

No, not at all - it was only when you pointed it out, that I realised that I totally mis-understood the point that Travis was trying to get across. Anyways I am a bit dense sometimes, so no hard feelings :)

Anyway, don't thank me - I only tinkered with it, Anders did all the hard work. This really is a Garage Punk/Psych/Stoner Rock monster. I Think I'm going to call this the "Jotnar" pedal when I box it up, in honour of Anders.

[Travis]

Did you try any higher gain germanium? A lot of people like to use higher gain for Q1 and lower gain for Q2 in fuzzrites, so the same probably applies here.

At the same time, I have no doubt it sounds great with Si for Q1, and I'm gonna try that. Thanks for the ideas!

[Beaker]

Yes, I tried a high gain Ge for Q1 and low gain Ge for Q2. Still did not sound anywhere near as good as Anders suggested choice (2N2222 for Q1 and MP38 for Q2). I don't have any NPN germanium transistors that are even close to the range of a 2N2222 - if you do, then I reckon they will work just as well.

As to how close it sounds to the original, I really don't know (I can only find one crappy demo), and I really don't care. I just know that this sounds nasty!

[Beaker]

Want to make this even nastier? I've just been getting ready to box this up, and accidentally run across a simple hack to make this self oscillate!

Simply connect a momentary footswitch between row 3 and row 8 on the left hand side of the board.

This will work with the modified, NPN converted version I have detailed above, but don't know if it will work with the original PNP layout.

[heuermh]

To clarify, to build the NPN converted version you refer to above, all that needs to be done is

 - use NPN transistors instead of PNP for Q1 and Q2 (obviously)
 - flip the 10uF electrolytic around, so its cathode (minus) goes to row I and its anode (plus) goes to row A
 - connect 9v+ to row A instead of 9v-
 - connect 9v- to row I instead of Ground +

?

Sorry to be thick; I'm still relatively new to this.

[rocket88]

Close. Use NPN transistors, and flip the electrolytic like you said, and put the +9V to the -9V and ground goes to ground +. Remember when converting PNP to NPN the electrolytics are flipped as are non-clipping diodes, and put the +9V to the -9V and ground goes to ground +.