SRS Exciter EQ

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

70's-ish Fuzz that was traced by Brad of Creepy Fingers, and traced/dissected over at the DAM forums.
Anyone want to take a shot at making up a vero layout? Mods, I posted this over at the Requests folder, so if this is out of order, please feel free to delete this thread.
SRSEQEXCITERSCHEM.png

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mictester
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Post by mictester »

Try this!
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Unverified!!
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Post by Nocentelli »

Is it any good? and what other trannies might work instead of the 2N3565? They don't seem that easy to find.
modman wrote: Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...

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Post by mictester »

Nocentelli wrote:Is it any good? and what other trannies might work instead of the 2N3565? They don't seem that easy to find.
It's a fairly ordinary silicon fuzz face with an output buffer and a tone control. It sounds pretty good, but has to be the first effect in a chain of effects because of the interaction between the circuitry of the guitar and the effect.

If you can't get the 2N3565 (which is a fairly low gain, low voltage silicon switching transistor), the 2N2222 would be a great replacement with almost identical properties. If you wanted to get silly and annoy a Texan redneck, you could use three of the transistors in a CA3046 array, sand the top off the device and claim that it's a special "proprietary fuzz chip"....
"Why is it humming?" "Because it doesn't know the words!"

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mictester
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Post by mictester »

By the way - a 10k pot for the tone control has much more range!
"Why is it humming?" "Because it doesn't know the words!"

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Post by Solidhex »

mictester wrote:By the way - a 10k pot for the tone control has much more range!
You'll get more mids (less scoop) out of the circuit when the EQ knob is turned fully clockwise with a 10K but the "action" only really exists in the first 2K's of the tone control. A 5K audio could be good possibly but a linear 10K will bunch all the action in the beginning of the pot rotation. I've tried it.
Lowering the value of C2 might provide a little more treble and give a different response to the EQ control. Its there to rid the Fuzz face section of high end oscillation and fizz. Depending on the gain of the transistors it can be selected to taste.

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Post by Dr Tony Balls »

mictester wrote:If you can't get the 2N3565 (which is a fairly low gain, low voltage silicon switching transistor), the 2N2222 would be a great replacement with almost identical properties.
I dont know if that's exactly right to say. The 2N3565 is spec'd with a pretty broad gain range (100-600) so i'd suspect that like a Foxx Tone Machine, these SRS circuits vary from unit to unit. 2N2222 are spec'd at a lower gain range (~40-300) so you might want to experiment with socketed transistors and see how the 2N2222s compare to some other higher gain transistors.

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Post by edkoppel »

hey dudes.
yeah the pedal sounds insanely huge.
Brad/Creepyfingers just posted a clip of his clone, with an added gain control (which seems to bring in quite a bit more dynamics than the OG), but for some reason the squelching high end is gone on his version? It actually sounds way more smooth now.


And I sent the original to Jerms a few weeks ago, so he has it to dissect.

here's the thread I posted on the dam forum right after the pedal came in:
http://stompboxes.co.uk/forum/viewtopic.php?f=6&t=10951

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Post by OnTheTundra »

mictester wrote:Try this!
SRS_EQ_Exciter.gif

You need a cut at E9 then its verified.

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Post by mictester »

Fixed!
Corrected
Corrected
Great sounding pedal. I've built it with 2N2222s, three transistors in a CA3086, BC107s and ME520s (best of all). The original devices would tend to have Hfe in the 80 - 150 range, so modern lower gain devices are best.
"Why is it humming?" "Because it doesn't know the words!"

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Post by chicago_mike »

I just wanna know who the redneck is...

I can make a road trip and annoy his ass for you! :mrgreen:
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Post by OnTheTundra »

This pedal is the shit. I love the sweep of the EQ. Extreme to extreme. Sounds Awesome.

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Post by Nocentelli »

OnTheTundra wrote:This pedal is the shit. I love the sweep of the EQ. Extreme to extreme. Sounds Awesome.
Great. Another addition to the ever-expanding "to build" list.
modman wrote: Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...

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Post by agoldoor »

Wow! Thank you SO much for finding and verifying that! I had built this when mictester graciously provided the vero, but then it never quite worked so I never debugged it! Just pulled this one off the shelf to fix it!

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