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DIY Stompboxes => Building your own stompbox => Topic started by: preciousmolina666 on March 26, 2017, 05:14:09 PM

Title: Ouput less noise
Post by: preciousmolina666 on March 26, 2017, 05:14:09 PM
if i use the figure 1 the best setting for me is knob "12 oclock" before my tubescreamer
im trying to do figure 2 which im thinking less noise before tubescreamer, what is the consequences?

https://www.dropbox.com/s/563k9p4nw57mccx/Untitlead.jpg
Title: Re: Ouput less noise
Post by: PRR on March 26, 2017, 09:08:55 PM
> im thinking less noise before tubescreamer

No.

#1 is a voltage-divider. A good audio building-block.

In #2, you are trying to "short out" the source. This can work on weak sources like guitars. But here you are trying to short-out an op-amp. This will not work well. The pot value has to be SO low that the coupling-cap loses bass, then the opamp strains and distorts.

Think of dimming your room light by putting a big wrench in the fusebox. Yes, the lamps will get dim, but the fusebox quickly blows-out.
Title: Re: Ouput less noise
Post by: preciousmolina666 on March 27, 2017, 07:46:00 AM
how about figure1 but 1k pots+500ohms to ground so its not going to short?
Title: Re: Ouput less noise
Post by: GibsonGM on March 27, 2017, 07:29:59 PM
It is not clear where this is going.   If it is the volume on your Tube Screamer, and you set it to 12:00, I think you are fine.  I would not alter the pot.

Or is this going BEFORE a Tube screamer?   Can you clarify?   Small value post like you suggest CAN be used, but will offer limited range of control and may affect what frequencies are passed along - what comes after me be depending on their value to some extent for filtering.
Title: Re: Ouput less noise
Post by: PRR on March 27, 2017, 11:46:12 PM
> 1k pots+500ohms to ground

An opamp (the way you show it) will hardly notice this load (output will not drop).
Title: Re: Ouput less noise
Post by: preciousmolina666 on March 30, 2017, 04:13:11 PM
QuoteIt is not clear where this is going.   If it is the volume on your Tube Screamer, and you set it to 12:00, I think you are fine.  I would not alter the pot.
after this preamp im going to tubescreamer bufferless, fixed at zero knob (gain of 10), then distortion/fuzz to max

QuoteAn opamp (the way you show it) will hardly notice this load (output will not drop).
what would you suggest, all i need is x1.5 gain

Title: Re: Ouput less noise
Post by: antonis on March 31, 2017, 06:30:11 AM
Quote from: preciousmolina666 on March 30, 2017, 04:13:11 PM
all i need is x1.5 gain

Figure 2 & 3 don't provide any gain..
(they're passive blocks..)