Colorsound - Power Boost / Overdriver

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
sonicvi
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Post by sonicvi »

You can get Sprague caps in 25uF, but 22uF works just fine.

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Post by controller700 »

Okay, thanks! I´ll try the 22uF.

I also found that layout:
Image

There is C13 in parallel to the bass pot, and that is also shown in the Colorsound Schematic, but the Prescription pedal doesn´t have it... So what would you recommend? Add C13, or leave it?

For the Transistors my plan is to test 2N3904 (like Prescription uses), BC547C (alternative for BC184) and BC549B (alternative for BC169). Good idea? :hmmm:

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Post by clintrubber »

I stumbled on the Colorsound Overdriver and thought it'd be a pretty straightforward build.
It will still be, but I was nevertheless surprised by the amount of circuit-variations (-errors ?) around.
I assume these originate from variations in original pedals over the years.

For instance:

* the transistors: while their exact name won't matter too much I guess (BC109/184/169/2N2222 etc),
I do expect a somewhat bigger (to even large) influence of the additions: -B or -C types (reflecting the current gain).

Have their been 'preferred current gains' around ? I know that this matters more for Ge-type FuzzFace circuits, but expect that for a Si-version it's still an issue as well (and that's what this is: a variation on the FuzzFace-topology plus EQ)
OK, 'adjust to taste' will be the approach, but starting from a decent set of values would be nice. Who knows more here?

* the 500 pF capacitor is 200 pF in the original old 1971 Colorsound schematic

* various resistors have different values


Bye,

Peter

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Post by clintrubber »

controller700 wrote:Okay, thanks! I´ll try the 22uF.
For the Transistors my plan is to test 2N3904 (like Prescription uses), BC547C (alternative for BC184) and BC549B (alternative for BC169). Good idea? :hmmm:
Hi,

If you go BC547C or BC549B you could also try BC550C or BC550B for potentially a bit lower noise (at least guaranteed by spec).

Bye,

Peter

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Post by sonicvi »

I tried BC109, BC184L,BC184C,BC169B, and 2n3904 in my clone and honestly I couldn't hear a significant difference between any of them.

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Post by clintrubber »

Perfect, less transistor-swapping, more playing ! :D

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Post by RnFR »

clintrubber wrote:I stumbled on the Colorsound Overdriver and thought it'd be a pretty straightforward build.
It will still be, but I was nevertheless surprised by the amount of circuit-variations (-errors ?) around.
I assume these originate from variations in original pedals over the years.

For instance:

* the transistors: while their exact name won't matter too much I guess (BC109/184/169/2N2222 etc),
I do expect a somewhat bigger (to even large) influence of the additions: -B or -C types (reflecting the current gain).

Have their been 'preferred current gains' around ? I know that this matters more for Ge-type FuzzFace circuits, but expect that for a Si-version it's still an issue as well (and that's what this is: a variation on the FuzzFace-topology plus EQ)
OK, 'adjust to taste' will be the approach, but starting from a decent set of values would be nice. Who knows more here?

* the 500 pF capacitor is 200 pF in the original old 1971 Colorsound schematic

* various resistors have different values


Bye,

Peter
i built one up with 109Cs, and i thought it was rather misbiased sounding.
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Post by clintrubber »

RnFR wrote: i built one up with 109Cs, and i thought it was rather misbiased sounding.
Thanks for sharing. Ehhhm, so high hFE is not the way to go. Which types did you end up with ?

Thanks

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Post by controller700 »

A friend will borrow me his Prescription Overdriver in the next days.

I will analyze it to the core, and if I like it´s sound I´ll maybe build a clone of the clone...

My report will come... :secret:

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Post by cpm »

RnFR wrote: i built one up with 109Cs, and i thought it was rather misbiased sounding.
and....
did you get to bias it?

i put 109B and it sounded misbiased with stock values, but adjusting collector resistors got it right

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Post by JimiB »

so where are your voltages now on the C,B, and E of your trannies?

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Post by cpm »

~5v on 2nd and 3rd transitors C

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Post by analogguru »

RnFR wrote:i built one up with 109Cs, and i thought it was rather misbiased sounding.
The (original) Power Boost was running on 18V while later the circuit was tweaked in the Overdriver to work on 9V only.

hfe shouldn´t have a big influence in this circuit (as long as it is not too low).

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Post by RnFR »

cpm wrote:
RnFR wrote: i built one up with 109Cs, and i thought it was rather misbiased sounding.
and....
did you get to bias it?

i put 109B and it sounded misbiased with stock values, but adjusting collector resistors got it right
yeah, i eventually rebiased and got it better, but it was a ways back and i never ended up boxing it up.
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Post by Otto »

Has anyone converted this circuit to positive ground? I'd like to have a stereo jack acting as a switch on the input side. I could wire the ground from the DC-socket through the stereo jack, but the problem is that I'm using a metal housing for the circuit so the DC-socket is grounded with both jack sleeves all the time.

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Post by cpm »

i had the chance to open one ot the newer Overdriver, and took some shots
from memory, in a quick look, i saw 47uF axial for the caps (and one 15uF), will check later for more components values.
pots were 2k2 rev log for gain, both 100k for tones, and 10k volume
transistor BC1xx (158? 168?...)

is it ok to upload hig-res pictures for the insides? or better link from an external server?
should it go into the "modern" subforum, as its a newer reissue??

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Post by Bernardduur »

Would love to compare em to my '96 model of which the pics should be around here.
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Post by clintrubber »

cpm wrote:i had the chance to open one ot the newer Overdriver, and took some shots
from memory, in a quick look, i saw 47uF axial for the caps (and one 15uF), will check later for more components values.
pots were 2k2 rev log for gain, both 100k for tones, and 10k volume
transistor BC1xx (158? 168?...)

is it ok to upload hig-res pictures for the insides? or better link from an external server?
should it go into the "modern" subforum, as its a newer reissue??
Hi,

If you have the opportunity for an external link then that'd always be good, dunno about hi-res & attachment limitations here.

Thanks !

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Post by RnFR »

just keep it in this thread. we like to keep everything nice and simple here. well as simple as you can get with all of the subforums. :wink:
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Post by cpm »

I forgot to take photo of the box :slap:
also couldnt measure voltages, .. i hope the owner doesnt get to know how i disassembled his box :mrgreen:

This is what i got for the schematic. The board says "POWERBOOST 96"
Its basically the same schem as the one i already had for the powerboost, noted "issue 1 14-6-71", but many different values.
Notice the connection of that 12k feedback resistor now it goes right into the gain pot, not to the emitter of Q1 like the old schem.

Also there are three values that i cannot read from the photos, so please have a look yourselves
Attachments
unfinished schem
unfinished schem
general view
general view
looks like a resistor, but schem suggests it should be a picoF cap
looks like a resistor, but schem suggests it should be a picoF cap
cap color codes wtf
cap color codes wtf
no value at sight
no value at sight

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