jason from volo wrote: Fri Sep 10, 2021 1:54 pm Another potentially "duh, stupid" question: are records that have "deeper grooves" more susceptible to this?

Not in my experience. It's more about how the mud is applied and what's in the mud than it is about how deep the boot tread is, if that analogy makes sense.

OK, I'll bite... what kind of record cleaners are we using?

I have a great number of old LPs that could benefit from a proper cleaning...

Teacher's Pet wrote: Fri Sep 10, 2021 5:54 pm OK, I'll bite... what kind of record cleaners are we using?

I use a Pro-Ject VC-S2 ALU. It's very nice. I was lucky enough to get it at a pretty severe discount.

That replaced a VPI HW-16 (not 16.5) that I got used from Craigslist. It worked pretty well but took a lot more rotations to dry - the seal wasn't great.

Why don't you see mixed values very often (500K vol + 250K tone, 1M vol + 500K tone, etc.) with guitar potentiometers? I thought the volume pot value had more influence with the overall brightness with both pots maxed, but after looking at the rhythm circuit on a Jazzmaster I think I may have that backwards.

Anyway, what does the value of each actually influence? I know if you increase the value of both you end up with brighter, but which pot has MORE influence over that?

I already understand audio (logarithmic) vs linear and what the cap value does. Would be nice to understand the rest.

tommy wrote: Mon Sep 13, 2021 10:03 am Why don't you see mixed values very often (500K vol + 250K tone, 1M vol + 500K tone, etc.) with guitar potentiometers? I thought the volume pot value had more influence with the overall brightness with both pots maxed, but after looking at the rhythm circuit on a Jazzmaster I think I may have that backwards.

Anyway, what does the value of each actually influence? I know if you increase the value of both you end up with brighter, but which pot has MORE influence over that?

I already understand audio (logarithmic) vs linear and what the cap value does. Would be nice to understand the rest.

This would be a pain in the ass to type out fully, so I'll try to do a short version.

First off, there are two things that are not mentioned at all in the above post. There are the impedance of the pickups and the impedance of whatever the guitar is plugged into. For a lot of these more basic discussions we can kind of ignore the pickup impedance, but if we get in too deep then it needs to be taken into account. However, the impedance of the first device being plugged into will have a huge effect on the volume and tone interaction and losses.

Shit, the more I type out, the more I realize that I need diagrams, so I'll just do a few more simple statements.

Volume knobs are voltage dividers. When full up, there is only resistance between pickup signal and ground. As the volume is turned down, there is an increase in series resistance and a decrease in resistance to ground. This causes signal loss due to the series resistance, and an impedance drop due to the lowering of the resistance to ground. This impedance drop can be exacerbated by the series resistance. This is why people put bright caps on volume pots. The bright cap allows high frequencies to bypass the series resistance in the voltage divider; it's a crude way to high frequencies that are lost from loading.

In my experience, higher value pots exhibit more high frequency loss when turned down. However, lower value pots give a darker sound when turned up to max. This is where the pickups impedance comes into the picture. The more impedance of the pickup, the louder it is, but the more its affected by the volume pot tonally. This is what active pickups were meant to solve. A low impedance pickup is fed into a buffer to drive the signal with high current. Then this signal then goes into a 10k or 25k volume knob. Since it is a low impedance, high current signal, the lower value pot doesn't exhibit any loading, and the lower value causes less high frequency loss when turned down. Of course, most guitarists don't like active pickups because it doesn't sound and feel quite like the classic guitars that they love.

Now, tone knobs. Tone knobs are a variable resistor and a cap to ground. The cap bleeds the high frequencies to ground, and the resistor blocks the bleeding. The more resistance, the less high frequency loss. It's very straight forward. Also, a higher value tone knob can be turned down to the same value as a lower value tone knob at max. For instance a 500k tone knob wired up as a variable resistor might equal 250k as a variable resistor when it is turned to 7 or 8 (out of 10). It could be argued that the only reason to use a lower value pot in a tone knob is to have greater resolution. This is also why no-load tone pots exist. At the top click, it's like the tone knob isn't even there.. or the tone pot is at infinite resistance. A slight tick down and then it's like stock guitar tone at max.

My guess is that the reason volume and tone knobs usually match is because it's cheaper and easier for the guitar companies. Let' say I'm making 1000 telecasters. It's probably cheaper for me to buy 2,000 250k pots rather than 1,000 250k pots and 1,000 500k pots. Plus, if there's a mistake on the wiring line and they get switched, then the guitars sound wrong.

Personally, I have no-load tone pots in 2 of my 3 teles. More often than not, I end up turning the tone down because I just want to take that last little top edge off. One guitar just came with it and the other was an experiment. I find then unnecessary, but nothing is harmed by having it in the guitar and it's more hassle to swap them.

Hope this helped on some level.

Neal used my Marshall JMP 2204 in practice Thursday, sounded great. Took it to the Campout Friday and it was DOA.

Symptoms: Not getting power for some reason. Power indicator light on the mains switch did not come on.

What I had time to check: Fuses all appear to all be in order

What I feel like are the next logical things to check and within my skill level: the light bulb in the switch (admittedly, in the stress of the moment I didn't think to check to see if the tubes actually lit up), and the power cable itself which I believe is original and admittedly not the best-looking upon visual inspection. I'll probably clip the end of a good IEC and wire that in there.

Any other easy/obvious suggestions I should consider? I didn't reseat the tubes because it still has the back on and I didn't really have time to futz w/ it but regardless the power light should still have come on.

Garth wrote: Tue Sep 14, 2021 8:47 am Neal used my Marshall JMP 2204 in practice Thursday, sounded great. Took it to the Campout Friday and it was DOA.

Symptoms: Not getting power for some reason. Power indicator light on the mains switch did not come on.

What I had time to check: Fuses all appear to all be in order

What I feel like are the next logical things to check and within my skill level: the light bulb in the switch (admittedly, in the stress of the moment I didn't think to check to see if the tubes actually lit up), and the power cable itself which I believe is original and admittedly not the best-looking upon visual inspection. I'll probably clip the end of a good IEC and wire that in there.

Any other easy/obvious suggestions I should consider? I didn't reseat the tubes because it still has the back on and I didn't really have time to futz w/ it but regardless the power light should still have come on.

You're correct. If the Mains fuse is good, about the only things that could be at fault are the switch itself (either the contacts or the bulb) or the power cable or socket, if you have one. MAYBE a connection inside opened up but that seems unlikely unless it's been modified.

I wouldnt focus on anything tube-related. If there was a problem there it would blow a fuse.

Dr Tony Balls wrote: modified

Yeah this is where I'm sweating. I bought it knowing it had been modded to at least have an effects loop, then later reversed. I'm a little scared to see how bad it actually is in there.

Garth wrote: Tue Sep 14, 2021 10:10 am

Dr Tony Balls wrote: modified

Yeah this is where I'm sweating. I bought it knowing it had been modded to at least have an effects loop, then later reversed. I'm a little scared to see how bad it actually is in there.

Other than the shock of what you might find, I wouldnt be too worried. None of the modifications could really be creating the problem save for if someone adjusted the mains wiring and did a shit job soldering it.

That's a good point dr. I was going to say I believe it had the "bright-cap mod" done to it (and also reversed) but you're absolutely right that nothing there would affect power. Fingers crossed.