Build Your Own Clone Message Board

If you're not tired of answering questions yet, maybe you can help me with this comment of yours. I was not aware that a volume pot value change would/could modify the frequency in this way. If it does do this, could you add a resistor to the pot to lower it's value, and put the resistor on the switch? Or would this override whatever property of the pot it is that we are making use of here?

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- Robert ...

The output capacitor and the volume pot form a simple high pass filter. The cut-off frequency can be altered by changing the value of the capacitor or the pot.

With the output capacitor at 4.7µF, the cut-off frequency is well below any frequency generated by a guitar (bottom E on a bass is about 40 Hz); regardless of whether you use a 10 kΩ or 100 kΩ pot you won't hear any difference. Change the output capacitor to something like 100nF and try a 10 kΩ and then a 100 kΩ pot - you'll hear a lot less bass with the 10 kΩ pot.

As for your resistor idea - use a 100nF capacitor and a 10 kΩ pot and connect a 1 kΩ resistor (via a switch if you want) between lugs 2 & 3 of the pot. As you turn the pot down, higher frequencies will be attenuated, but much less than bass frequencies. If you want to do this for bass guitar it's exactly the same set up but with a 100 kΩ pot.

Gracias. Makes total sense once it's told to me . . . I'm a ways off from being able to look at it and ave it make sense!

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- Robert ...

Is the release mod the same as the attacks switch on the BYOC Armstron Twin?

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If you mean the Sw3/C12/C13 part of the Armstrong Twin, then, yes it's the same. I didn't know it was called an Attack Switch.

Yup, that's the one. I wasn't really sure cause the schematics are a little different
Yeah, they call it an attack switch... well, that's if my memory isn't totally gone.

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Tonmann, I am building mine just for bass. A very simple version without the switching. If I understand correctly, I should do all the Keen/Hammer mods (R9 from 220k to 200; R13 from 10k to 100K; C6 from 4.7uf to 1uf; and C7 from 47uf to 10uf). Do I have that right? Or are you saying it's not necessary to use the 100K pot if I drop the value of the output cap?

Sorry if it's a dumb question! But here's another one: Should the pot be an audio or linear pot?

Alright, I have a few problem with my build. Here are some pictures of the top. The bottom I'll shoot if this turns up nothing.




I am using the op-amp pot mod and the cap select mod. It sounds like there is nothing going on but I get signal passing. The trim pot make noise when turned. The op amp pot does nothing as does the cap switch. The volume pot at the end works, however, it is not even unity at full.

I would be grateful for any help.

John

Hope that John L eventually got an answer to his question... I wondered if his build might actually be working fine...but that the adjustments were subtle enough that he did not hear them.

I did the simpler build with just the volume pot on the outside. I did the Keen/Hammer mods. Since I planned to use it for bass, I socketed C1 and C5. I ended up leaving C5 "stock" but in C1 I used a .1uf cap instead of the .047uf stock cap. I also used a 100k audio pot for volume, after trying both the 10K and 100K. (audibly more bass with the 100k pot...just as Tonmann indicates).

It worked great for me. The pedal ads a slight hiss, but was very quiet when I used it with a battery. It adds a nice light compression that I can best describe as sort of "thickening" the sound. Really nice. Nice boost too.

The only problem I had with it was that I was getting nasty 60 cycle hum when I used an external power supply. At first I thought this was the power supply's fault, since I was using a wall wart. So I several progressively better approaches to regulating and filtering the power supply with very little success.

Then a wandering EE (deltafred) suggested a mod to the pedal, that virtually made the hum disappear. Anyone interested may want to take a look at this discussion. Mods to the OS are on pages 3-4

http://www.bassesbyleo.com/forum/viewtopic.php?f=10&t=217&start=20

Rich