how to attenuate volume in a circuit?

[caress]

i'm wondering about different ways to attenuate volume in a circuit with too much of it.

obviously you can add a trimpot in series with your output volume pot, but are there any downsides to doing this?  other - smarter - methods?

here are some circuit possibilities:

fuzz face - http://gaussmarkov.net/images/bff-schem.png
big muff - http://www.freeinfosociety.com/electronics/schemview.php?id=110
fuzzrite - http://eu11.stripper.jp/pulcino/blog/images/fuzzrite.gif

[jayp5150]

Rather than use a trim, you can just use a fixed resistor when you figure out what value you need.

I've never built a FF using the 8.2k off the collector of Q2 that needed attenuation, though. I don't like having to turn the knob past half to get unity, and my FF was at like 70% to get unity. That may have just been my results, though.

[caress]

ok well let's say i used fixed resistors...

if i have a 50k trim and it's set to the mid point, would i insert a 22k from the output cap to volume pot lug as well as a 22k to ground (it would look like a divider)...?

are there high/low-end loss issues when doing this?  impedance problems?

[jayp5150]

ok well let's say i used fixed resistors...

if i have a 50k trim and it's set to the mid point, would i insert a 22k from the output cap to volume pot lug as well as a 22k to ground (it would look like a divider)...?

are there high/low-end loss issues when doing this?  impedance problems?

Well, if you put a resistance to ground, wouldn't that act as a parallel resistance to the pot? I'm not 100% sure on that...

I would think you would just add a series resistor before the volume pot, that way there is always a minimum resistance even if the pot is dimed. I don't see the need to use a divider.

But then again, I'm not as bright as I should be about some of this lol.

[John Lyons]

Which circuit are we talking about here?
If we know what were dealing with we can give a more accurate suggestion.

john

[caress]

i guess i'm looking for ways to attenuate different types of circuits in general.
a while back i built an uglyface for a friend with a muff tone control and sho output amplifier.  it was REALLY loud...  so i guess there i'm interested in attenuating either the uglyface OR the sho.  pretty different to be sure...

uglyface - http://www.geocities.com/tpe123/folkurban/fuzz/snippets.html
sho - http://www.matsumin.net/diy/bunkai/Z_vex_SHO/Z.Vex_SHO_sch.BMP
(ok i know the sho schematic has been seen differently... i used the one with 2 1n4148 and a 100k to ground at output)

*fuzz face types to start since there are so many and can apply to many different circuits - especially helpful in designing cascaded circuits...  (such as the recently talked about ff > big muff)

[John Lyons]

Well, the SHO is a boost circuit so there is no secret there.
It really does not add anything but boost and that's what it's used for.
No need to attenuate it. It has a boost level after all...just turn down the level.
Or use a different boost with adjusted values to get less gain.
For a BJT use a resistance from emitter to ground. etc etc.

Fuzz face as built stock doesn't get too loud and it has a level pot...simple enough

Voltage dividers are the most common. A resistor in series with a resistor to ground and the
junction of the two is the output. Same at a volume pot but fixed level.
Make the resistor to ground bigger = more level. Make the series resistor bigger = less level.

It depends on the circuit. FF is a resistance off the emitter with a cap at the divider junction to ground.

john

[waveman]

I was wondering the same sort of thing. John, answered exactly what I wanted to know. Thanks 

[caress]

Well, the SHO is a boost circuit so there is no secret there.
It really does not add anything but boost and that's what it's used for.
No need to attenuate it. It has a boost level after all...just turn down the level.
Or use a different boost with adjusted values to get less gain.
For a BJT use a resistance from emitter to ground. etc etc.

Fuzz face as built stock doesn't get too loud and it has a level pot...simple enough

Voltage dividers are the most common. A resistor in series with a resistor to ground and the
junction of the two is the output. Same at a volume pot but fixed level.
Make the resistor to ground bigger = more level. Make the series resistor bigger = less level.

It depends on the circuit. FF is a resistance off the emitter with a cap at the divider junction to ground.

john

cool.  i figured as much with the voltage divider configuration, i just thought there might be a more elegant way to lower the gain... the good ol KISS method works best here.   
i guess a better question was how to lower the output level BEFORE the volume pot, so that there is less volume at hand.  i'll work with the divider as well as trying out a resistance from E to ground.

[John Lyons]

You can always use a smaller volume pot as well.
This will make the volume range smaller.

The volume pot is a voltage divider after all 

john

[caress]

i already dropped the volume pot down to a 10k!  maybe i need to go to 5k... will this reduce highs/lows at all?

[John Lyons]

Which circuit are you wanting to attenuate again?
Where on the dial is the "right" volume with the 10K?

john