What is "highest" high gain pedal you have heard?

[space_ryerson]

Thanks John and Paul, that's what I had surmised, but wanted to be sure. Paul, it's a solid state amp, so it doesn't get that hot!

[R.G.]

RG, I have a semi-related boneheaded question. I've noticed in one of my amps that certain resistors get pretty hot. If they get hot, then they will likely add noise. If I use a higher wattage rated resistor, would that reduce how hot the resistors get? (...and potentially lower the noise?)

Yes, what's already been said applies.
If all other things are equal, the coolest resistor has the lowest noise.
If all other things are equal, the lowest resistance resistor has the lowest noise.
If all other things are equal, the resistor nearest the front of the amplifier contributes most to the noise.

The biggest contributor tends to be high value resistors at the very front of an amplifier. All of their noise gets the full gain of the amplifier applied to it. However, resistors that get hot tend to be wirewound or metal oxide as John points out, and these have the lowest intrinsic noise. Carbon comp has the highest. It's often true that high power resistors tend to be near the output of an amplifier, and so have much less gain applied to their noise. They also tend to be lower value than front end resistors, so they get lower noise from that.

All taken together, it's likely that the power resistors are not contributing much noise in your amps. Could be, can't tell without looking at the schemo and parts list, but likely. Circuit has some effect too. Power supply resistors which feed bypass caps  have their noise shunted to ground by the bypass caps, so they can't add much thermal noise.

[space_ryerson]

Thanks RG. The offending resistors aren't directly in the signal path, and are used to lower the DC voltage from 40V to either 24V or 12V. I didn't think that they were necessarily adding any noise, and upon further reflection, I'm likely suffering from BUTMS, or as we commonly know it, blind urge to mod syndrome

[Paul Marossy]

Thanks John and Paul, that's what I had surmised, but wanted to be sure. Paul, it's a solid state amp, so it doesn't get that hot!

Oh. Of course a SS amp runs much, much cooler.

Thanks RG. The offending resistors aren't directly in the signal path, and are used to lower the DC voltage from 40V to either 24V or 12V. I didn't think that they were necessarily adding any noise, and upon further reflection, I'm likely suffering from BUTMS, or as we commonly know it, blind urge to mod syndrome

I don't think they would add any noise, as they are not in the signal path. If they were on tubes, that might be a different story.

[mac]

the highest gain pedals i have are a tonebender mkII and a germanium big muff pi, but never set them above half.
imho, too much gain, ie more and more extra harmonics, destroys a guitar/amp tone.
btw, i´m 44

mac

[ppatchmods]

ds-1...for sure... http://beavisaudio.com/flash/DS1.html  

[Tube2stomp]

RG, what about thermal noise of parallel resistances?
I found two answers that are obviously not the same... both from sources that should know and sometimes in the same paper!

Lets say two 1M resistors in parallel, one answer say:
"look at it as a single resistor of 500k"
Sounds logical, right? they are in parallel.
Thermal Noise voltage for 500k over 20kHz comes to 12.87uV.

Second answer say:
"These are voltage sources so they add"
Also sounds logical... right?
So now we have a gain of 3dB
25.75uV!!!

And that's before injecting in the input noise of the amplifying stage... which is also in parallel?
Who's parallel?

[Lurco]

do two parallel batteries of 9V each add up to 18V 

[anchovie]

do two parallel batteries of 9V each add up to 18V 

http://www.google.com/search?q=parallel+batteries

[StephenGiles]

It's funny. Mother Nature is lurking unrecognized in the background here.

When a guitarist says "more gain" he means "more distortion". The way he gets his distortion is by higher electronic gain banging on some kind of limiting.

Unfortunately, gain always brings up noise as well as signal.  There are professionals who devote their entire careers to designing low noise gain devices. It's a fundamental problem. Thermal noise is not optional. It's in every device which is either active (all amplifying devices) or has a resistive component. There are other noise mechanisms which can be reduced, but thermal noise you have with you always. You get flicker noise from random signal processes and active devices, and excess noise from some resistors, and those are on top of thermal noise.

Thermal noise in resistances is bigger with bigger resistances and with higher temperatures. Guitars use high-impedance pickups and force us to then use high impedance inputs to not lose treble. So we can't get out of front-end noise by going to lower impedances the way RF devices do.

Temperature is what it is. No guitarist I know of would dunk his high gain pedal in a tank of liquid nitrogen to cool the devices to make it less noisy, so we live with the temperature-generated thermal noise.

Bottom line, we can't get below some minimal amount of noise coming into the gain devices we use. We can only live within the noise they generate. We can - and often do - make the noise situation worse by clumsy designs or poor device choices.

One trick pros use to get the best signal-to-noise ratio is to use big signals to start with. Unfortunately, we're kind of stuck on the pickups we have, so the signal levels are fixed. We can't get bigger signals without amplifying, and that means that we live with the noise from that amplifier.

Then there's distortion. When we distort a signal, we clip off the tops and bottoms. Noise is generally smaller than signal (we HOPE!) to start with, so by amplifying both signal and noise because we can't do anything else, and then selectively clipping off the amplified signal to make it distorted, the resulting signal is smaller, but the noise does not get clipped. That means:

Every signal clipping action makes the signal-to-noise ratio worse.

So the way Mother Nature has things set up, asking for more gain means also having to accept more noise. Asking for more "gain" (to a guitarist, distortion really) means asking for even worse noise. The two are fundamentally tied together by The Way The Universe Works.

Knowing this leads to the best noise practices.

1. Use the biggest signal source you can get to start with.
- ugh. We're stuck here. Can't change the signal source.
2. Use the lowest signal impedance you can get.
- ugh 2. We're stuck with those vintage guitar pickups we love.
3. Since the noise of the first stage is amplified by all the other stages, make the first stage of amplification as quiet as you can and also make it as much gain as you can.
- sticking equal lumps of gain in a string will make things worse from the noise perspective.
- to let this do its work, don't distort in your first stage; give it a big power supply voltage so it's not clipping there. This lets you preserve the best signal to noise ratio you can get for any further gain stages.

As you recognize, typical pedals do *none* of these. Signal-to-noise is something that simply doesn't come up until we get an especially flagrant offender.

In my darker days I think about putting a knob labeled "More!" on pedals. This knob merely adds in more hiss and noise from a noise source, nothing else. I bet it would be popular as long as the user didn't know what it actually did, and there would be long discussions about what the best setting of the "More!" knob was.

And remember, bad playing sounds proportionally worse at higher volume

[Tube2stomp]

do two parallel batteries of 9V each add up to 18V 

Really asking or being sarcastic?
I'll take the later (more interesting )
So you're saying there are now three options?
Common sense say "Not likely"... if you'll parallel 1,000,000 resistors of 1Mohm I doubt you will get the same noise voltage.
With that logic shouldn't a 2x12 speaker setup produce the same SPL as a single 12" speaker?
But it doesn't
And still two 9v batteries in parallel produce exactly 9v
I'm not an EE, or an E, or aspiring to be one. I'm just an MAH (multidisciplinary autodidact hobbyist ).
With that said >>> batteries produce DC voltage >>> 0Hz >>> 0 phase >>> 0+0=0
Have you ever "heard" a 0Hz signal?
Noise is AC.

Here, I found one of the papers on the subject of noise, it's from TI:
http://focus.ti.com/lit/ml/sloa082/sloa082.pdf

[R.G.]

RG, what about thermal noise of parallel resistances?
I found two answers that are obviously not the same... both from sources that should know and sometimes in the same paper!

Lets say two 1M resistors in parallel, one answer say:
"look at it as a single resistor of 500k"
Sounds logical, right? they are in parallel.
Thermal Noise voltage for 500k over 20kHz comes to 12.87uV.

Second answer say:
"These are voltage sources so they add"
Also sounds logical... right?
So now we have a gain of 3dB
25.75uV!!!

And that's before injecting in the input noise of the amplifying stage... which is also in parallel?
Who's parallel?

The *AC* noise voltages add in the RMS sense - the root of the mean square of the sum of the two RMS noise voltages is produced.

Note that this does not work the same way with DC voltages no, two parallel 9V batteries do not produce 18V. 

[big bustle]

Just curious (with so many in here) what is the highest high gain pedal you have used, heard, or made?

Craig Anderton's "Optimum Fuzz Adapter". Op-amp, no feedback. Full open loop gain.

i googled googled and gooled but couldn't find a schem for this beast. anyone care to share?

[RDV]

Since I finally did the updates to my Dr Boogey it's changed my life... er... sound!

RDV

[Lurco]

so if we find 2 resistors whose noiselevels behave oppositely, we can cancel the noise by parallelling them 
or somehow noiselessly invert the phase of the noise of one noisy 1M resistor, and add these 2 noisesignals, it will disappear  ( )

[FiveseveN]

Thermal noise is random. You cannot find or build a device that is "inversely random" or "out of phase" with some other randomness. All you can do is choose the device with less inherent noise.

[caspercody]

Big Bustle,
Go to Layouts Gallery (at top o page), and enter comparator fuzz.

[alfafalfa]

Since I finally did the updates to my Dr Boogey it's changed my life... er... sound!

RDV

What updates ??

What did you do to it ?

[deadastronaut]

yeah!..what updates to the boogie?.......

i'd be interested too!........

[Ibanezfoo]

Yeah yeah!  Come on!  Share!