There are guys who believe stacking caps like this, especially different types of caps (ceramic/ poly etc...) changes the tone and response. I've talked to some of them about it. My ears are pretty good but I don't hear the differences nor am I inclined to deep dive into paralleled capacitors for tweaking the tone vs one capacitor of the correct value.
Yeah I kind of had a feeling it didn’t have much to do with the tone. And yeah that’s kind of out there with doing it to detect copy cats. I was also thinking maybe a way for someone to put out a design and call it their own. There’s a schematic floating around of a Cali Mod that uses parallel 15nF caps in the tone stack for the bass and mid. I mean it’s not the typical .022uf like I usually see in a lot of the Marshall based TS and it’s the first time I saw that parallel cap thing pop up in a schematic. I mean I am relatively new to this stuff but I’ve definitely looked at my fair share of schematics over the past 5 or so years since I started.
Interesting. I know technically paralleled caps should halve ESR and ESL, but I haven't looked into whether it makes a difference in this case. Sounds like it probably doesn't. I've also seen paralleled ceramic and tantalums recommended by data sheets for supply rail decoupling, but in that case I think you're way out of the audio band.
I Actually like using .0022uF or similar values as a depth option depending on the tone I’m shooting for, I’m not good at identifying what frequencies I’m hearing but I want to say it seems to do something to the low mids or something in the midrange. I did a 3 way depth mod on my one amp with .0022, .0044, & .0069. Still trying to experiment with the values.
.0022 on the depth pot is more midrangey. But I’m talking about putting a .0022 cap by itself in-line with the NFB, not on the pot. In that schematic above, replace the .1uF with a .0022 uF. You’ll be amazed at how huge the amp will sound.
That’s a great idea! I’m definitely going to try that. Thanks! Always new stuff to try, everytime I learn something new I’m like a kid in a candy store. lol
When I was modding my JCA20 I went through a lot of depth caps. I found an old .0033uf cap and it changed the amp entirely. I wanted a little more from the circuit and whenever I would remove that cap, I HATED the amp, so I ended up stacking another cap with it to get a value and tone I wanted. What’s interesting is I found another cap from the same company that was .005uf and it didn’t sound the same. That cap is magical and I’ve always kept my eye out for more. It was magical enough that I avoided mentioning what it is in this post. I’m actually being serious.
It’s always good to test each value yourself. Take a small notebook and write down your findings for later reference.
When I was modding my JCA20 I went through a lot of depth caps. I found an old .0033uf cap and it changed the amp entirely. I wanted a little more from the circuit and whenever I would remove that cap, I HATED the amp, so I ended up stacking another cap with it to get a value and tone I wanted. What’s interesting is I found another cap from the same company that was .005uf and it didn’t sound the same. That cap is magical and I’ve always kept my eye out for more. It was magical enough that I avoided mentioning what it is in this post. I’m actually being serious.
It very well could have drifted. I only have a fluke meter.
I vaguely remember you mentioning it in another discussion about depth circuits but I don’t know if you mentioned what it was. I won’t say what I think it is just in case lol I’m thinking maybe I need to invest in a decade box to make this a little easier although it won’t cover the various brands and models at least I should be able to dial in the value a bit easier.When I was modding my JCA20 I went through a lot of depth caps. I found an old .0033uf cap and it changed the amp entirely. I wanted a little more from the circuit and whenever I would remove that cap, I HATED the amp, so I ended up stacking another cap with it to get a value and tone I wanted. What’s interesting is I found another cap from the same company that was .005uf and it didn’t sound the same. That cap is magical and I’ve always kept my eye out for more. It was magical enough that I avoided mentioning what it is in this post. I’m actually being serious.
Also that JCA 20 is still one of the best sounding videos I’ve heard of a Jet City amp. I know you chose to take them down due to the designs being someone else’s but those videos are what got me into Jet City modding in the first place!When I was modding my JCA20 I went through a lot of depth caps. I found an old .0033uf cap and it changed the amp entirely. I wanted a little more from the circuit and whenever I would remove that cap, I HATED the amp, so I ended up stacking another cap with it to get a value and tone I wanted. What’s interesting is I found another cap from the same company that was .005uf and it didn’t sound the same. That cap is magical and I’ve always kept my eye out for more. It was magical enough that I avoided mentioning what it is in this post. I’m actually being serious.
I will definitely keep you posted once I've tried it. I added some caaps to my recent parts order but I'm really considering getting a decade box to make tasks like this a bit easier.
Yes I am also a fan of the .0068 for a lot of the tones I play through. I include .0069 on my 3 way depth switch. Only reason it’s .0069 and not the .0068 is because of how the on-off-on switch gets wired I had to combine a .0047 and a .0022 in parallel. It sounded good so I kept it at 69. My next build I plan on using a relay setup so I can include more choices and use an actual .0068
Yeah that’s true. Hadn’t really thought of that.