colorsound overdriver tranny hfe ??

[dansamp]

so about six months ago I put together an overdriver clone and it didn't work right
I finally sat down the the layout and figured out I had wiried the gain pot incorrectly
then I found a porblem with one of the caps in the tone circuit
anyway I have the Q2 and Q3 with 5.17 and 5.20 volts on the collectors using BC109 tranny's
my questions is this:
what hfe is best for this circuit I seem to remember that the tranny's I had all measured about 300 hfe
is this ok or should I get some other tranny's

thanks 

Dan............

[slacker]

I used BC109s for mine, with HFEs of around 300-350 and it sounds great. I don't think the HFE matters too much I just like the sound you get with BC109s compared with other types. Your voltages look fine, according to the schematic Q2 and Q3 should have 5 volts on the collectors, mine were a bit high so I increased the collector resistors from 1k8 to 2k.
Bernardduur posted that his 96 reissue overdriver uses BC184Bs so you might want to try those.

[dansamp]

thanks for the info
my question is because I am comparing it to a Throbak overdriver boost pedal and the Throbak seems much louder
also how can I get more treble adjustment out of this circuit??
it seems best when the treble is all the way up but it could still use more

thanks again

Dan...........

[Bernardduur]

Check the '96 schematic I made.....

Louder??? Mine is already UBER loud

[dansamp]

Bernardduur,
is there a link
I can't seem to find it

Thanks

Dan.

[slacker]

Here's the link http://www.diystompboxes.com/smfforum/index.php?topic=52507.0.
If you're using the overdriver as a booster rather than a fuzz then it will behave differently with different amps, but like Bernardduur said it should have more than enough volume. I use mine with Fender Twin and I get plenty of clean boost with the gain and volume pots at about 12 o'clock.
The Throbak clips are into a Marshall 18watt clone and even the supposedly clean amp sounds are quite dirty to start with. On those clips some of the distortion is coming from the amp and some of the clips are using their additional germanium stage.

[dansamp]

thanks guys I will try those tweaks

I think I will start with the 10k treble pot ??

by the way I have the Throbak pedal (I bought it since I couldn't get mine working properly)
I can return it if I want to but I am thinking of keeping it

it's just hard to accept the price since I am pretty close with mine

Dan.....

[slacker]

Cool, I thought you were just comparing yours with the sound clips.
The Throbak pedal has trimmers, which are probably to adjust the bias of the transistors. You could try measuring the collector voltages on the Throbak to see how they've set it, that might explain why it's louder. You could then adjust the collector resistors on yours to get the same bias. I don't know if that would do anything, but it would be interesting to try.
They might be using a bigger volume pot, say a 500k which would possibly raise the volume a bit.

[petemoore]

  The tone controls seem wierd on mine. 100k lin for both, and smooth movement to the freq response over both knobs, but they're interactive in a strange way, I've tweeked them up down and sideways with the gain knob and the high end response...I'm thinking I'd rather have the OD tone but with a more standard voicing [just caps to shape lows/highs] and a simpler HF rolloff cap/pot.
  Of course I don't 'hhink I put the wrong cap on the treble control, I might have to take another look.
  Just did, can't say for sure which value[s I'd want changed to get...probably higher high end and more mid scoop..shoot I don't even know..that TC is a strange one to get a handle on, just looking and diddling from the knob shaft side...obviously they've got 4 variable resistances, the top half [bass] has resistance in it so that the bottom part [treble] has less resistance to it except for the resistance of the HP filter caps.
  Maybe raise the resistance in the middle [mid scoop?]//by splicing added resistance in.
  Adding resistance to or around the bass pot [cut some of the plenty bass] in relation to treble with resistance,
  and reduce to say .0047uf one or two of the treble knob caps so only a sparklier high end is let through.
  ..I'm not too good with figureing more than about four lugs worth of tone knob and related R's and C's..
  I'll have to take another look at it, thanks for letting me type that out.

[dansamp]

the guy at throbak said on the 18watt forum he tweaked the tone circuit to be more interactive
I think it is a baxandall ?? tone circuit

either way it did seem louder when I hade the collectors closer to 6 volts
I did measure the throbak pedal and I seem to remember they were around 6 volts
I set mine to 5 volts 'cause that's what the schematic calls for

just for comparison all things equal the throbak is at 3:00 on the volume knob when mine is at 12:00

mine gets good sounds it's just not as loud and I wish I had more treble

on another note somewhere around here somebody plugged in a BMP tone circuit instead of the two knobs and seemed to be pretty happy

I don't know if there is a layout though

Dan...........

[flektor]

I built mine with BC184L, less noise than the BC109s.

BC184L gain range is around 300 and 350 hfe, and they soud great, but I like the BC184 (around 150-250 hfe) in Q1 and Q2.

Recently I found a bunch of BC169 (less gain than the BC169C, that is the original Colorsound ODR transistor). Soon I´ll test them.

The BC169 gain is around 150 and 250 hfe.

[flektor]

if you wanna try these trannies take care with the pinouts, the BC169 and the BC184 have Emissor-Collector-Base pins.

[dansamp]

ok took a peak into the Throbak pedal
Q3 is at 6.4 volts on the collector
and Q2 is at 5.4 volts

the tranny's are  2N222A

and the 4th one which is a Ge and is engaged via a switch is 2N404 NJS

there are three 10k trim pots and one 500K (gain trimmer) pot

on my clone unity volume is about 2;00-3;00 o'clock (i subbed a 250kA pot)

I also tried a 1kC gain pot which took out all the gain
so I put back the 10KB pot

anyway thats it for now

Dan.............

[slacker]

ok took a peak into the Throbak pedal
Q3 is at 6.4 volts on the collector
and Q2 is at 5.4 volts

Interesting I might have to try tweaking mine, like you I just set mine to about 5 volts.

the tranny's are  2N222A

Do you mean 2N2222A? That would make sense because they are low gain about 100-200 Hfe.

I also tried a 1kC gain pot which took out all the gain
so I put back the 10KB pot

I wonder if your's is wired up right, because making the gain pot smaller shouldn't reduce the amount of gain. Maximum gain is when the pot is at 0 ohms, so the value of the pot shouldn't matter. If anything reducing the value of the pot would increase the minimum gain but not affect maximum gain.

[dansamp]

the vero layout shows the gain pot wired backwards with the middle and bottom leg wired together (as you look at the back of the pot)
with the legs pointing to the right this way it works counter clockwise


http://aronnelson.com/gallery/albums/slackers-stuff/newcsoboard.jpg

so I wired the 1KC pot opposite that (it's the only reverse pot I have)
yeah I meant 2N2222A
but how would lower gain tranny's make it a louder circuit ??

[slacker]

the vero layout shows the gain pot wired backwards with the middle and bottom leg wired together (as you look at the back of the pot)
with the legs pointing to the right this way it works counter clockwise


http://aronnelson.com/gallery/albums/slackers-stuff/newcsoboard.jpg

so I wired the 1KC pot opposite that (it's the only reverse pot I have)

I thought I'd changed that, perhaps I did but didn't upload the new version, I'll sort it out.
The pot should still give maximum gain when set to zero resistance though even if it's wired up backwards so changing the pot value shouldn't affect the maximum amount of gain.

yeah I meant 2N2222A
but how would lower gain tranny's make it a louder circuit ??

I just meant that it made sense to use 2N2222s because they were probably a similar gain to the original transistors. It's probably the bias settings that make the pedal louder.

I don't suppose you can tell what the germanium stage on the Throbak does. I don't want to clone it, I'd just be interested to see what they've added, I guess it's just a booster in front of the original circuit?

[dansamp]

not sure what it does either
it is mounted off the circuit board and held in place with clear silicone
it mainly works with the volume knob turned down and adds distortion type sound
he has it set up to be a psuedo attenuator
with the volume turned up it isn't very noticeable

I seem to recall it is a Ge tranny and Ge diode

[dansamp]

Oh yeah there is also a pre-gain switch that he describes it as tightening up the low end
I think it just cuts some of the boost so it's not as aggressive (better suited for humbuckers)

[p.eat]

Hi,

  very interesting topic! I haven't seen a Throbak unit in person, but from the description of the unit I think the Ge pair is used as clipping diodes. Can you see where they are inserted in the circuit dansamp?

My guess for the pre-gain switch is that it inserts a trimmer as a series resistance. You can see this in several Fuzz schematics. It has the same effect as turning your guitar volume down.

Peter

[slacker]

Yeah the Ge setup might be used for clipping or possibly to get some diode compression like in a couple of Joe Davisson's designs.
I think you're right about the pregain, I tried exactly that when I was building mine, didn't bother with it in the end but it did clean up the sound nicely.