Secretefx - Secret-1 STD overdrive [traced]
- YuGi
- Degoop Doctor
Hi all, I dissected the secret-1 pedal. The work is already on the italian forum http://www.fennecelectronics.it, http://www.fennecelectronics.it/smf/ind ... ic=11684.0
The soul of this hobby is sharing informations, so.. my two cents to the community As you can see, lot of degooping work
The soul of this hobby is sharing informations, so.. my two cents to the community As you can see, lot of degooping work
Last edited by YuGi on 09 Feb 2014, 16:56, edited 1 time in total.
- YuGi
- Degoop Doctor
I removed and measured all components. This is the "naked" PCB
And finally the schematics
What you think about? On the other forum we are discussing about in and out buffers.. is not strange that biasing? - IvIark
- Tube Twister
Information
Thanks for this
What are the transistors?
What are the transistors?
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP
- IvIark
- Tube Twister
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Great, thanks
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP
- Nocentelli
- Tube Twister
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+1YuGi wrote:What you think about? On the other forum we are discussing about in and out buffers.. is not strange that biasing?
It looks like it's missing a 1M to ground from the base of both BJTs. That would make sense.
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...
- IvIark
- Tube Twister
Information
In the Tubescreamer and similar the base resistor goes to VCC/2
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP
- YuGi
- Degoop Doctor
The schematics is absolutely correct (I have the PCB on my desktop..).Nocentelli wrote:+1YuGi wrote:What you think about? On the other forum we are discussing about in and out buffers.. is not strange that biasing?
It looks like it's missing a 1M to ground from the base of both BJTs. That would make sense.
I simulated the buffers with LTspice and the headroom is better then a classic bjt buffer (bias with 1M to v/2 and 10K emitter resistor). Why?!
- Cub
- Cap Cooler
I don't remember where, but I saw a demo if it in front of a number of Big Muff pedals and it was a really nice sounding combination.
Thanks for sharing, YuGi !
Thanks for sharing, YuGi !
I wish I were a chestnut tree, nourished by the sun.
With twigs and leaves and branches and conkers by the ton.
With twigs and leaves and branches and conkers by the ton.
It's possible to bias a buffer in this way, but it's definitely the worse one, simply because it's higlhy hfe and temperature related.
A classic 2 resistors partition from supply and ground it's more stable and it permits to use a wide range of transistors (wide range of hfe), without any relevant difference in bias point. It will sound the same... or better (more dinamic, because you can adjust the bias point by design, not trying some different BJTs)!
If we connect the 1M resistor to V/2 like in a classic tube screamer, we've less trouble (less voltage difference across the resistor) and it will bias at good point.
If a circuit works fine from some decades, why we need to change it?
A classic 2 resistors partition from supply and ground it's more stable and it permits to use a wide range of transistors (wide range of hfe), without any relevant difference in bias point. It will sound the same... or better (more dinamic, because you can adjust the bias point by design, not trying some different BJTs)!
If we connect the 1M resistor to V/2 like in a classic tube screamer, we've less trouble (less voltage difference across the resistor) and it will bias at good point.
If a circuit works fine from some decades, why we need to change it?
- Cannibal
- Breadboard Brother
Aside from the buffers, is R5 just a positive feedback resistor? Also the frist opamp max gain is around 500x, so this thing should have a massive amount of distortion going on, instead is just a medium gain overdrive. Am i missing something?
Seiche wrote:there's a difference between being drugged (I don't think it was only booze) and retarded.
- YuGi
- Degoop Doctor
The inverting opamp mixes dry and wet so the resulting wave is smootly distorted.Cannibal wrote:Aside from the buffers, is R5 just a positive feedback resistor? Also the frist opamp max gain is around 500x, so this thing should have a massive amount of distortion going on, instead is just a medium gain overdrive. Am i missing something?
- IvIark
- Tube Twister
Information
Someone pointed out an error in the layout, the link to pin 2 should be going to pin 3, but I can't edit the post above so here is the updated layout.
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP