Do Tiedown resistors affect tone? R.G?

[ethanw]

I got to wondering if the 1 meg resistors we all use on the input to prevent popping affect the tone of pedals. From what I understand (could be wrong!), any resistance going to ground in the signal path will bleed off some signal. Enough to affect the sound? Not sure. Opinions?

Ethan

[R.G.]

The answer is - maybe.

The reason any loading affects tone is that your pickups are inductive. That is, they can put out less signal current at higher frequencies than at low frequencies.

Any loading at all will reduce the high frequencies and thereby cut some of the treble out of your signal.

However, the real question is never "if", it's "how much?". For most people, the signal of a guitar directly into a tube amp with a 1M grid resistor is the reference. There are some people who demand higher impedances and say they produce more "tinkle"; they're probably right. But most people are OK with a single 1M load.

If we introduce a pedal into this, we have to look at the details. If the pedal is a buffered input, then the worry about loading begins and ends at the pedal input. The loading of the cable from the guitar to the buffered input is all the load the guitar ever sees because the pedal drives the rest of the string to the amp. So the input impedance of the pedal determines the loading.

In a true bypassed setup, if you do the setup correctly, the pulldown resistors are on the effects side of the bypass switch. They are not connected to the signal in bypass, so they can have no effect. When the effect is switched in, its input impedance loads the guitar, and the output drives the rest of the chain, so the input impedance is all you're concerned with. Done properly, the guitar only sees one pulldown resistor at a time.

If you do this improperly and put pulldowns on the signal line when the effect is bypassed, yes, you can introduce loading by having, for instance, ten 1M resistors clinging on to the un-effected signal.

Good question. The answer is in the details. Once a signal has been buffered, the worry ends, but watch what you hang on the un-buffered signal line.

Cable capacitance may be worse than resistive loading.

[ethanw]

Thanks for the thorough answer R.G.! Specifically, I was thinking of the TS-808, which does indeed have a buffered input. I noticed that the "Grand Laff" modded 808 schem doesn't haven't the 1 meg while most DIYers seem to add it to 808's. Since the 808 input is buffered, the 1 meg should not be a problem if I understand correctly-

Ethan

[96ecss]

Thanks for the thorough answer R.G.! Specifically, I was thinking of the TS-808, which does indeed have a buffered input. I noticed that the "Grand Laff" modded 808 schem doesn't haven't the 1 meg while most DIYers seem to add it to 808's. Since the 808 input is buffered, the 1 meg should not be a problem if I understand correctly-

Ethan

Just a note about schematics. Not all schematics show the 1M resistor at the input. It doesn't necesarily mean it shouldn't be included though. Are you building a TS-808 or modding one?

Dave

[Shepherd]

When can you go lower than 1M?

[R.G.]

Any time you want.

The lower the resistance, the more treble you lose if a guitar is plugged right into the effect input. If it's never a guitar, usually it doesn't matter much because other effects can drive much input load without treble loss.

Pick your own poison.

[darron]

you could also use a 2m2, but they are hard to find in metal film and don't look as cool

i modded my tubescreamer for true bypass and it definitely helps to have the caps discharged for pop. use grounded input on bypass and you don't need the 1m resistor at all and it doesn't degrade the clean or processed signal.

try a little experiment: short a 56k or so (which is 0.056M!) between the tip and sleeve of an audio jack with your guitar signal playing into an amp and here how much difference there is. try it before and after a buffer.

[darron]

ohhh. and don't forget that a volume control pot of say 100k will always have 100k or less of resistance to ground. think about the ones in your guitar.

[ethanw]

"Just a note about schematics. Not all schematics show the 1M resistor at the input. It doesn't necesarily mean it shouldn't be included though. Are you building a TS-808 or modding one? Dave"

I'm building one, a BYOC.


"I modded my tubescreamer for true bypass and it definitely helps to have the caps discharged for pop. use grounded input on bypass and you don't need the 1m resistor at all and it doesn't degrade the clean or processed signal."

I like this idea, I have the diagram from it somewhere, I've been meaning to try it. I might have used it in a looper but not on a pedal. Good post about it here: http://www.diystompboxes.com/smfforum/index.php?topic=56137.0

Ethan