A couple of questions regarding the Clandestine Preamp

[Explorerman]

Hi,I’m looking to build this one (plan to use orange drop 225p caps and carbon film resistors) and have a couple of questions:

- I can only seem to source a 1N4748 zener diode not a 1N4748A. The 1N4748 is still a 22v 1W zenner diode, will this be ok to use?

- Does the PCB come with instructions with biasing? I have no idea how this is done.

- how does the Clandestine preamp compare to the Chase tone secret preamp?

Cheers

 

[mkstewartesq]

Hi. I just built this pedal a few weeks ago. It’s amazing and is 100% an “always on” pedal on my board. You can find my build thread here.

1. Can’t answer your question about the diode. I was able to find the exact “A” version required at Tayda.

2. Here is an excellent guide to biasing this pedal. Review the whole thread – it’s only a few posts.

3. I’ve never owned the Chase Tone version but, as noted above, I think this thing sounds amazing.

Mike

 

[Explorerman]

Hi. I just built this pedal a few weeks ago. It’s amazing and is 100% an “always on” pedal on my board. You can find my build thread here.

1. Can’t answer your question about the diode. I was able to find the exact “A” version required at Tayda.

2. Here is an excellent guide to biasing this pedal. Review the whole thread – it’s only a few posts.

3. I’ve never owned the Chase Tone version but, as noted above, I think this thing sounds amazing.

Mike

Thanks mate! Great to know, I still don’t really know what to do regarding bias - what voltage to aim for, but I guess it will make more sense once I build it.

 

[mkstewartesq]

Thanks mate! Great to know, I still don’t really know what to do regarding bias - what voltage to aim for, but I guess it will make more sense once I build it.

Read that thread. It’s laid out very simply. You measure the voltage on the resistor at R101 and then bias your JFET drain to roughly half of whatever reading you got at R101. Then adjust to taste. I think most of us end up somewhere around 12 to 13 V.

 

[Explorerman]

No worries, thanks. Also, with the toggle switch - is it the model with the typical solder tags or the pcb mount type?

 

[mkstewartesq]

No worries, thanks. Also, with the toggle switch - is it the model with the typical solder tags or the pcb mount type?

You can use either. The PPCB boards will generally accommodate both types. All of mine are solder lugs.

 

[Explorerman]

What do most people do with the LED, do you solder the LED legs straight to the pcb (would need to get the length right to line up with the heights of the switch and pot) or solder wires to the between the pcb and LED?

Progress shot so far:

 

[Fama]

What do most people do with the LED, do you solder the LED legs straight to the pcb (would need to get the length right to line up with the heights of the switch and pot) or solder wires to the between the pcb and LED?

Progress shot so far:

View attachment 67531

I generally put the switches and pots carefully into the holes on the PCB and then guide it into the enclosure, so the pots and switches line up. Solder the pots and switches there. For that kind of a LED which is apparently built in to the bezel, I would probably put that in it's place and try to guide the legs into the correct holes on the PCB and solder it with the PCB, pots and switches and the LED all in the enclosure so it's the correct length.

I normally use a different kind of bezel, but the main principle is the same, I have the LED in place with the PCB in it's correct place and solder the LED in. Then take the PCB out and finish the wiring.

 

[Nic]

For that kind of a LED which is apparently built in to the bezel

I think it's just a regular led that gets inserted in the bezel. You can screw the bezel on the enclosure and slide the led in and out. The hard part may be to get the little plastic "spacer" in the bezel.

 

[Explorerman]

Yep the LED just slides into the bezel and a spacer keeps the LED in there tight. That might be the best plan - place the LED in the bezel in situ, then solder the legs onto the pcb.

 

[Explorerman]

Also, is there any reason why I can’t power it up without the pot and jacks and have a go at biasing? (The IC would be in obviously). While I wait to drill and paint my enclosure, or should I wait till it’s all boxed up?

 

[Fama]

Also, is there any reason why I can’t power it up without the pot and jacks and have a go at biasing? (The IC would be in obviously). While I wait to drill and paint my enclosure, or should I wait till it’s all boxed up?

I think you could power it up and have a go at biasing, but biasing by ear is also a valid way to do it usually, so I'd suggest you wait until it's all done and bias as the last step. That way you can also check how it sounds.

 

[Feral Feline]

Also, is there any reason why I can’t power it up without the pot and jacks and have a go at biasing? (The IC would be in obviously). While I wait to drill and paint my enclosure, or should I wait till it’s all boxed up?

There's a saying:

"Rock it before you box it".



Find out if the circuit works, get it working.
Then when you box it, and it doesn't work, you've already narrowed down the problem to a ground fault, bypass wiring or similar.
If you box it before testing, and it doesn't work, it can still be the same type of problems as above but also possibly ...
so. much. more.
Then likely you have to pull it out of the enclosure anyway to troubleshoot.


So... power it up, have a go at biasing.

 

[Explorerman]

Ok, so got this thing powered up, I’m measuring 23.8v on the left side of R101 and about 22v on the right side. The above link says to use the highest number of R101, so I’ve biased to 11.9v (23.8 / 2) Does this sound right? I’ll do some more testing by ear once it’s boxed up and can do some better ABing with the footswitch.

It does sound really nice, only tried with single coils, but to me it sounds best on the bright setting, the other two settings seemed to drown out or remove some the chime of the Strat (if that makes sense), but really happy with what this does to my signal!

Edit: I also measured the power draw on this, it’s only 5mA. Whereas I read that it can draw between 150-200mA. Does this sound right?
Cheers

 

[Fama]

Ok, so got this thing powered up, I’m measuring 23.8v on the left side of R101 and about 22v on the right side. The above link says to use the highest number of R101, so I’ve biased to 11.9v (23.8 / 2) Does this sound right? I’ll do some more testing by ear once it’s boxed up and can do some better ABing with the footswitch.

It does sound really nice, only tried with single coils, but to me it sounds best on the bright setting, the other two settings seemed to drown out or remove some the chime of the Strat (if that makes sense), but really happy with what this does to my signal!

Edit: I also measured the power draw on this, it’s only 5mA. Whereas I read that it can draw between 150-200mA. Does this sound right?
Cheers

I don't remember what bias i used in mine at all, but if it sounds really nice, you're good. Personally I use mine in the "both" position since with my strat the bright gets too bright. The low one was nice when I changed my strings though, helped me through the phase where they are way too bright (for me) for a day or two.

As for power draw, again if it sounds really nice, you're good. To be honest I don't think the original can draw 150 to 200 mA, can it? Or maybe it has some super complicated switching? That still sounds like an absurd amount for what is essentially a charge pump and one JFET. I wonder if it's some kind of marketing trick, "trust me it sounds better if it can draw up to 150mA than with just 50mA" or something like that. It does say so on their website, but who knows.

 

[Explorerman]

I remember reading someone’s build report on here and said that it was power hunger and draws around 150mA. I would have expected mine to be similar, just worried I might have an issue.

This is also from a current listing for the CT SP on reverb, it draws 130mA: