need help with cathode follower circuit

Started by REGNAD, August 30, 2009, 12:42:57 AM

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REGNAD

heres my pecking order as of now...
strat>valvecaster>compressor>BK tube driver>rams head muff clone>dd-3(wet signal to amp B, bypass signal to>carbon copy>valve jr

Ben N

Quote from: REGNAD on November 09, 2009, 08:36:34 PM
why is it that these 3 pedals "feed" off each other? by themselves they are almost completely quiet. also, how do you tell which components are the cheaper variety?

Everything adds noise; well-designed effects minimize that noise to acceptable levels. However, besides generating noise, amplifiers also amplify what enters them without distinction--music, noise, they can't tell the difference. Each of those pedals has oodles of gain through multiple gain stages, all of which amplify what enters many times over. The dirt boxes also work by clipping the signal, which is why the output level is not enough to blow your amp to kingdom come with all that gain. But cl/ipping has most effect on signal peaks, not the weaker parts of the signal, like that noise floor, which keeps getting higher and higher with each successive gain stage. If that's not bad enough, compressors are amplifiers that do discriminate between weak and strong signals, and generally try to boost the weak ones while cutting the strong ones. Once again, noise gets a bigger boost, relative to the music. Now, each of these pedals by itself can be designed and built with enough care that the noise doesn't get out of hand, but combining them in series means that you are boosting the noise in greater proportion than the signal over and over again, and with each successive stage your signal to noise ratio is degraded more.
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DougH

What kind of noise is it? If it's hum from the power supply, that's a separate issue from background noise that accumulates through the signal chain. If that's what it is- do some searching here and at GEO for "ground loop".

If it's a matter of trying to use multiple gain pedals, fuzz boxes, distortions or etc- just learn to enjoy it (;-) or use a noise gate. There's really no way around that. With enough gain, anything and everything will get picked up by a sensitive input stage, amplified and re-amplified down the line.

If it's background noise in the signal (hiss, etc) in combinations other than multiple gain pedals, then you have to do what Ben said, look at how to minimize noise in each individual pedal, or, use a noise gate.

A buffer (follower) will not help you here at all, and may make matters worse. A buffer is basically a current amplifier and is used to drive current down a long line, for offsetting the signal degradation that can occur.
"I can explain it to you, but I can't understand it for you."

REGNAD

so does the cathode follower not isolate one effect from another? im certain its not power supply noise, and if im set at unity on my three OD's could that still be a culprit?

Gus

#64
You might get more help if you post the voltages at the cathode and 330,33K node and the power supply voltages.

What is the heat supply a nonregulated or regulated supply?  What is the B+ supply DIY etc.?

How do you know the noise is not from a power supply?
Did you try a different tube?

How does guitar to buffer to amp sound?

DougH

Yeah, stick a pedal with buffered bypass like a Boss pedal in your chain. That will show you the effect of a buffer in a hurry. No magic in tube buffers so don't worry about that. The difference, if perceptible at all, between that and SS will be minimal.
"I can explain it to you, but I can't understand it for you."