Breadboarding Tone VEndor mk2 troubleshoot

[NickC]

ok everything seems to "work" except the general output volume is really too low, I know it's a mess but maybe someone can see something I don't see, thanks in advance

 

[BuddytheReow]

Not sure what this resistor is supposed to do. It's just sitting in the power rails and won't do anything for the overall circuit since the power will just bypass it. If this R3 per the schematic then you'll have to adjust your layout.

 

[NickC]

GREAT it works! thank you so mutch guys!
this is my first breadbording project!

 

[BuddytheReow]

The question we have to ask is naturally: Do you know why the output was reduced?

I would like to know for my own benefit. Tone Benders are your specialty

 

[BuddytheReow]

Suspense is not really my jam....

The Rc3a/Rc3b network in the MK II (Rc2a/Rc2b in a FF) is a fixed voltage divider.

We all know the effects of moving a transistor stages bias point toward the power rail and to ground. Gating occurs initially and then silence happens for voltages at the power rail and glitching/velcro initially and then silence toward ground.

For the nominal 470/8.2k string with a 9 vDC source, not much of the signal is attenuate across the 470.

If you have experimented with the nominal 470 ohm RcXa value, you'll know from experience that as you increase that value, the output volume increases.

Since @NickC was essentially bypassing RcXa, the output volume would have been super low (Jumper = 0 ohm RcXa).

Is there a limit to how big the 470 resistor can be? Could I throw in, say, 1k or 4.7k?

 

[Chuck D. Bones]

For the nominal 470/8.2k string with a 9 vDC source, not much of the signal is attenuate across the 470.

Incorrect. Most of the signal is attenuated.

For a 8.2K / 470Ω voltage divider, the loss is 25dB. Changing the ratio of those resistors affects the volume. Changing the sum of those resistors affects the bias.

Is there a limit to how big the 470 resistor can be? Could I throw in, say, 1k or 4.7k?

Yes, of course there is a limit to how large either resistor can be. If you go too large, then the last transistor will saturate and you get either gating or no signal. You can make the 470Ω resistor larger for more volume. Keep in mind that you are affecting both the bias & volume when you change that resistor. If you want to change only the volume and keep the bias constant, then you need to change both resistors, keeping the sum constant.

 

[BuddytheReow]

 

[szukalski]

Some really useful knowledge.

I just want to say. I love these posts of yours. I’m very much a beginner learning these things but this stuff is gold. Thanks.