"brightening" a signal in an overdrive

[mordechai]

I have built a version of the ROG Peppermill and used Mark Hammer's SWTC at the end of the circuit before the volume control.  It works great, but I would like to "brighten" the signal (i.e., add treble) going into it so that when I turn the pot down to the 12 o'clock position, the tone is what it would otherwise naturally be if the SWTC were turned all the way up on the unmodified circuit.  Any suggestions?

[ashcat_lt]

Probably change a cap value somewhere, maybe and/or a resistor.  Can't see it, though so I can't tell you which.  Were you hoping we'd go google thar for you?

[mordechai]

Um, no.  Innocent question. 

[Kesh]

Post schematics

[Mark Hammer]

To supplement my offline note, if one used a toggle to re-connect the ground end of the tone cap from ground to the input lug on the tone pot, you would have the functional equivalent of a "bright switch" on a Fender amp.  The  Bright switch normally straddles a cap across the input lug and wiper of a volume pot.

Here's an example of what I'm talking about:


This is the UNivox Square wave.  You can see that there is a fixed resistor and a pot, leading up to the volume pot.  That pot+resistor pair has a cap in parallel with it.  When the pot is at 0 ohms, the .001uf cap provides only minimal advantage for the treble content  When the pot is at fyull resistance in combination with the fixed resistor and the volume pot, that whole combination acts like a 250k+27k+50k = 327k volume p[ot that can never be turned up above 15% for the mids and bass, but is much much louder for the treble bypassed by the .001uf cap.

Re-connecting the ground side of the tone cap to the input lug of the pot will not get you the mosquito tones of the Square Wave, but WILL give you the option of having variable brightening OR dulling, via the same pot.  As per our other discussion, the amount of brightening providied will depend on the value of the tone pot, relative to the volume pot.  A 10k tone pot and 500k volume pot would not get you much brightening, where a 50k tone pot and 50k volume pot would.

[mordechai]

So, with something like the SWTC (as per our offboard discussion), with the addition of the .001uF cap from lug 1 to lug 2 of the tone pot serve the same purpose in terms of kicking in as a "bright" switch (though obviously not as a "switch"), since the cap at lug 2 is going to ground?  Or would the .001uF cap need to connect to a different point in the circuit in order for this to occur?

[Mark Hammer]

jack Orman explains it better than I can from work, since he has illustrations.  Check here for clarity:  http://www.muzique.com/lab/swtc.htm

[Thecomedian]

Probably change a cap value somewhere, maybe and/or a resistor.  Can't see it, though so I can't tell you which.  Were you hoping we'd go google thar for you?

Don't be a dick. This isn't something you find very quickly without a lot of reading. All that google information comes from Previous Q & A or people actually fielding the answers voluntarily without being asked. How different is it for someone to come here and ask? I also hate the policy concept of not "necroing" threads, or people saying "search" for threads. If something is still relevant, 2-10-1000 years later, it's still relevant. If someone asks the same old question because a thread was so old that "netiquette" determined that others couldn't "necro" it, it's not their fault that it wasn't in the most recent pages.

The alternative is to say that after X amount of time passes, forums are not meant to be used for discussion anymore, since after a certain age, all questions have been asked and answered and people need to stop being lazy or relying on spoonfeeding and search forums and never post.

that sounds dumb to me.

[slacker]

Think you've misunderstood what ashcat meant, the guy's asking for help but he's provided very little info to enable people to help him. Unless you're familiar with the circuits he's talking about you're going to have to search them out. Unless the circuit's very well known it's always a good idea, and polite, to provide links.
Agree with your necro posting comments though, although that's not something that's frowned on round here.

On topic something to try would be a cap in parallel with the 1k resistor off the source of the mosfet, try values around 100n, this should boost the treble.

[pinkjimiphoton]

Probably change a cap value somewhere, maybe and/or a resistor.  Can't see it, though so I can't tell you which.  Were you hoping we'd go google thar for you?

Don't be a dick. This isn't something you find very quickly without a lot of reading. All that google information comes from Previous Q & A or people actually fielding the answers voluntarily without being asked. How different is it for someone to come here and ask? I also hate the policy concept of not "necroing" threads, or people saying "search" for threads. If something is still relevant, 2-10-1000 years later, it's still relevant. If someone asks the same old question because a thread was so old that "netiquette" determined that others couldn't "necro" it, it's not their fault that it wasn't in the most recent pages.

The alternative is to say that after X amount of time passes, forums are not meant to be used for discussion anymore, since after a certain age, all questions have been asked and answered and people need to stop being lazy or relying on spoonfeeding and search forums and never post.

that sounds dumb to me.

there is SOOOOOOO much infor contained in this forum alone that no one person could ever absorb it ALL.

so i gotta agree. yes, sometimes (often) the question has been answered, but often if one person is asking, 100 others will benefit from the answer.

it's better off to ask stuff on the forum, rather than off line, so that the whole community can benefit.

there are NO "stupid" questions, and often there are multiple paths to the correct answer.
on some topics, a forum search can turn up nothing, or it could turn up 1000 posts. folks that have been here for a while often can help us newbs fine tune our searches, or suggest previous posts (sometimes having nothing in common with the necro thread, but contained nonetheless).

by all means tho, be a dick when ya get the guys who come here expecting someone else to do all their work for them so they can profit by ripping off someone else. but no reason to troll anyone else here; this is NOT HCEF.


that said...sometimes, you can also get away with, as mark suggested, a simple treble bleed.

if the distortion gets muddy when you turn it down, but sounds good cranked, you can try the simplest form of "bright switch", even easier than what mark suggests.

simply put a small cap...say, 100p to 10n or so between input and wiper of the volume pot. same as a "treble bleed" on a guitar. when it's up, it has negligible effect on the circuit. as you turn down, it brightens up a little. if you find the right value, it should have close to the same treble content from full blast to turned way down.

i've done it on a few pedals now. it's a simple, easy way to help. you can also run another cap to ground if you want to limit the treble output, just like a tone control.
if you do both, you can adjust the max treble content of the signal, while still maintaining enough high end to make it cut.

may not work on every circuit tho. but try it, and see if it works for ya.

[midwayfair]

Op: Stick a bright cap on the MOSFET stage from the source to ground. Try 100nF. It'll boost the mids and treble content. You can go smaller, say 22nF, if you need to.

[Mark Hammer]

In fairness, mordechai and I had already started discussing offline, so the "under-detailing" of the request is probably a reflection of how easy it is to forget the difference between what you say and what you think you've said.  Happens to me all the time.

[mordechai]

I want to thank everyone for their suggestions, which are very helpful.  And I want to clarify something.  

I am probably not the only person who comes out here already shaking with intimidation.  All I did was ask a simple question.  Not mean spirited, not angry, not duplicitous...just a simple question.  I see that there was a lack of detail, which ashcat asked for.  And had the reply ended with that request, I think it would have been fine.

But that's not where it ended.  The cynical, rhetorical question that followed made me feel VERY stupid, and thoroughly unwelcome.  The subsequent responses to that response helped, but the residual impact is that now, when I have another innocent question, I am hesitant to ask it because I am afraid that some person out there who knows the answer will be condescending in their reply and basically tell me to buzz off because how dare I, an intellectual peon, attempt to broaden my horizons.

So to you, ashcat, who asked with obvious disdain if I expected him and everyone else to google answers for me, I will say this: I hope that when YOU next ask someone for help, they will not make you feel the way you made me feel.  Because it will take much more than a cap in parallel with a resistor to brighten your mood should someone treat you in a similar manner.

[pinkjimiphoton]

mordechai,

don't take it too harsh man. shit happens. sometimes people get a little short, i don't think ashcat meant to upset you that much.

by all means, please DO ask any questions...even if they seem silly, cuz man, i make mistakes all the time, and i learn new stuff here EVERYDAY cuz someone asks.

please don't feel singled out, and please do not hesitate to ask anything. even seemingly "dumb" questions are quite valid, and we all learn from each other. sometimes us newbs can even teach the "old dawgs" new tricks.

no one learns from doing stuff right. we all learn (hopefully) from our mistakes, and the mistakes of others.

so maybe we can all agree a mistake was made in civility here, and move on. like i said, this isn't HCEF, so no need to "troll" anyone.

i, for one, think the OP was right on target with the mission of the forum.

don't be intimidated by some of the geniuses and gurus on the forum. EVERY SINGLE ONE was once a guy like us, struggling to learn.
and every single one of them is a hell of a guy, someone (or gal, as the case may be) and i'd be honored to hoist a brew with any of the folks here, any time if the opportunity arose.

no high and mighty here...just good folks, who mostly all remember what it was like and are eager to help..

sorry to hijack your thread, but i felt you deserved a response to validate your feelings, and hopefully make you feel more at home.

peace

[John Lyons]

+1, Hang in there.
Next time just try to include all the info you can.
With a schematic it's a lot easier to make a suggestion.
Don't feel bad. 

[midwayfair]

I think Ashcat's response was poorly worded (and needlessly confrontational) and is now being misunderstood. He meant that most people couldn't comment on how to change the circuit if they couldn't see what you were working on. The "that" in "Google that for you" is the schematic, as suggested by Kesh, not the answer, except that Ashcat forgot to include the word "schematic" in his response. I'd like to give him the benefit of the doubt because he does post helpful comments elsewhere on the forum.

To be honest, when I first saw the op's question, I hesitated to give my personal answer because I didn't want to assume he was building the stock Peppermill. ROG circuits are hardly obscure around here, but sometimes versions of them might be. The Umble circuit I know has about 10 different versions posted and some have almost every value changed.

This is one of the problems inherent in communicating online. This would have been resolved in seconds in person and discussion would have continued as normal without anyone's feelings being hurt.

op, stick around. I assure you that intellectual curiosity is valued around here and that sometimes a couple people just have a bad day.

[pinkjimiphoton]

+1.

i'm sure it was inadvertant. that's one of the problems with cyber discussion.

true, sometimes we'll get the occaisional troll asking for people to do all their work for them, and yes, it can be fun to engage 'em...

but i don't believe anyone meant to intentionally hurt any feelings. we're all mates here for the most part!

[mordechai]

Alright.  Well...I'm getting over it, so thank you all for talking it out with me. 

As for trolling, I think it's probably a fine line.  I have gotten some great ideas from the folks out here and have been able to tune my fuzz circuits exactly the way I want to because of the discussion here.  Now that I'm turning to overdrives, I hope to do the same.  But perhaps trolling is just a version of plagiarizing, whereas the more noble course of action is taking inspirational ideas and applying them to something new. 

As it happens, the discussion of the bright switch that Mark discussed above has been very helpful and I've managed to come closer to the sound I want from it.  I will apply the cap/resistor parallel arrangement on the source of the MOSFET too, and see which one works better for what I've come up with.  One of the neat thrills for me with this is seeing...and **learning**...how brightening the signal before or after different stages yields different effects, subtle and otherwise.  And working those lessons into new projects is something that I find very rewarding.

[pinkjimiphoton]

dude, i don't mean YOU were trolling. i meant trolls just go off on people for no reason.

[ashcat_lt]

I really am sorry if I came across as a dick. 

Definitely don't let me (or anybody) stop you from asking questions.  I usually don't post "UTFSF" posts, though sometimes I will link to very recent threads which cover the same ground.  Honestly, I'd just looked at 3 or 4 threads where people were asking "how do I do this to that" without any links or schematics or anything.  I'm sure there are people here who could draw the Peppermill from memory.  Heck, if you'd said Rat, I could have given a few pointers without looking, but I'm not sure I've ever really looked at this particular pedal.  I take it from what I've heard that it's some sort of overdrive/distortion/fuzz thing?  Couldn't tell you even if it's transistor or opamp based or what.  Is that it that Mark posted above?

So yeah, let's both use this as a learning experience. 

Shake?