Non-CF Clipper?
Moderators: pompeiisneaks, Colossal
Re: Non-CF Clipper?
Oh cool! That'll be a Lot easier than try to find space on the board for it. Thanks!
Re: Non-CF Clipper?
The bridged T and the CG tone controls use basically the same parts, it's just a matter of how you wire'em up. I'd definitely recommend trying both. The T has the advantage that, when you crank it, it's basically a flat response (which can be useful sometimes). The CG varies the amount of mid a bit, but while doing that, also sweeps it's cut point a bit.
Given that you're finding you need to pad the signal after the first stage, that the CG style knob is known for being kinda lossy, that isn't necessarily a bad thing.
But for two resistors, two caps, and a pot--either style offers substantial flexibility without taking up a ton of real estate. You may ultimately prefer the "tweed" style control you currently have in there, but since you're not trying to clone a specific sound, you owe it to yourself to run through the options.
If you put in the CG and it's too lossy, remember you can just yank your 220k/220k divider stage out (or temporarily lift the leg going to ground).
Given that you're finding you need to pad the signal after the first stage, that the CG style knob is known for being kinda lossy, that isn't necessarily a bad thing.
But for two resistors, two caps, and a pot--either style offers substantial flexibility without taking up a ton of real estate. You may ultimately prefer the "tweed" style control you currently have in there, but since you're not trying to clone a specific sound, you owe it to yourself to run through the options.
If you put in the CG and it's too lossy, remember you can just yank your 220k/220k divider stage out (or temporarily lift the leg going to ground).
Re: Non-CF Clipper?
Being a mere basic notch circuit it can naturally be tuned to any frequency of preference. It's just the most usual configuration to tune up the values for a mid-range notch but the circuit could be tweaked to opearate at "bass" or "treble" frequencies as well.matt h wrote:... talking about a bridged-T, which gibson also used. I forget what amp model it is, but in some amp it's just simply a "tone" control rather than calling it a mid.
Bridged-T is not just a Gibson thing. You likely encounter it at many amps that do not have tone controls that introduce mid-range notch inherently. For example, with amps that have Baxandall-style tone controls its quite usual to find a T- circuit that introduces a mid-range notch whether in fixed or user adjustable form. Several Ampeg and Crate amps use that circuit for mid-range control of OD channels, I think they label it as "Shape" or something. ...But nevermind what it's called, we only care what it does.
An important point to heed is that the basic circuit doesn't operate at fixed frequency. When you adjust the level the notch frequency shifts up or down in interaction. Kinda like in that traditional passive "tonestack" circuit.
Re: Non-CF Clipper?
teemuk wrote: An important point to heed is that the basic circuit doesn't operate at fixed frequency. When you adjust the level the notch frequency shifts up or down in interaction. Kinda like in that traditional passive "tonestack" circuit.
That it do (sic), but the sweep of the CG is much more broad, as the upper portion of the pot ends up in parallel with the other resistor... through the pots rotation, it sweeps a rather lot more than the original bridged-T hooked together with the same component values.
Re: Non-CF Clipper?
I'm going to try the CG. The simple one I've got now is not doing it for me. As you said, I should try various things to get where I want to go. And if it's a bit lossy I can get rid of the divider or adjust it to taste.matt h wrote: If you put in the CG and it's too lossy, remember you can just yank your 220k/220k divider stage out (or temporarily lift the leg going to ground).
Been too busy the last couple of days to do anything. Maybe this week I can get some 'quality time' with it.
Re: Non-CF Clipper?
Okay, I finally got a chance to try some stuff. What I tried is the CG rig as shown below. It worked, boy did it ever work! Actually, it was way over the top, adding Tons of lows to everything. The control had a usable range of less than a quarter of its total range. And even then it was just too much for my taste.
I was searching for a different control because the one I had, I think it's like Blue deluxe or something? It worked well but when turn up (toward the treble end) you got more treble alright, bit it was at the expense of the low end - the bass was cut. I suppose it was meant to work that way but it's not what I'm looking for.
There's a Gibson take on the T style like the CG but slightly different. But I'm wondering if it will present similar issues. So, I don't know, there are a few options: the "Tilt" control, etc.
For now I put the simple control back in it - just a cap that bleeds treble off. But I'll be looking at other ideas.
I was searching for a different control because the one I had, I think it's like Blue deluxe or something? It worked well but when turn up (toward the treble end) you got more treble alright, bit it was at the expense of the low end - the bass was cut. I suppose it was meant to work that way but it's not what I'm looking for.
There's a Gibson take on the T style like the CG but slightly different. But I'm wondering if it will present similar issues. So, I don't know, there are a few options: the "Tilt" control, etc.
For now I put the simple control back in it - just a cap that bleeds treble off. But I'll be looking at other ideas.
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Re: Non-CF Clipper?
In defense of the tone-control, it didn't ADD lows... it just removed less of them relative to other things. haha I'd personally experiment with coupling and bypass cap values. (see, I told you they were huge!)
I've always wanted to like the til-control more than I actually do. It tends to sound best "somewhere near the middle" and makes you pissy that there's such wasted range. There aren't a lot of satisfactory one-knob options.
I've always wanted to like the til-control more than I actually do. It tends to sound best "somewhere near the middle" and makes you pissy that there's such wasted range. There aren't a lot of satisfactory one-knob options.
Re: Non-CF Clipper?
Yeah, I know it doesn't add lows, that's just how the ratio sounds.
I'll try whatever I can find, though it will be awhile because the pot I'm using has failed (cheap junk). So I'm ordering a few more. I've got a load of pots, none 500K audio of course. Ah well, I'll throw in an array of cap values to try.
I just got a new KT88 for my single ended guy. I'll play around with that until the parts arrive.
I'll try whatever I can find, though it will be awhile because the pot I'm using has failed (cheap junk). So I'm ordering a few more. I've got a load of pots, none 500K audio of course. Ah well, I'll throw in an array of cap values to try.
I just got a new KT88 for my single ended guy. I'll play around with that until the parts arrive.
Re: Non-CF Clipper?
Have you tried to change values of the cap(s)?
Also, a resistor to ground will dampen the effect of the eq.
Also, a resistor to ground will dampen the effect of the eq.
Re: Non-CF Clipper?
To ground from where? Wouldn't that drain more of the signal? This is already pretty lossy. I'm not trying to contradict you but there's only so much signal to begin with even if I get rid of the divider.roberto wrote:Have you tried to change values of the cap(s)?
Also, a resistor to ground will dampen the effect of the eq.
I think Matt's right: it's tough to get a satisfactory tone control out of a single knob. I might even just stick with the simple treble roll off, or maybe even none at all and just use the guitar controls. Don't know what I'd use that knob for then, though. PPIMV?
Re: Non-CF Clipper?
The opposite. If you place a resistor between the actual grounding point of the eq and the ground, the effect of the eq will be dampened (and changed a bit).
Re: Non-CF Clipper?
Ah! Well that's very different! 
I'll give that a try.
However, am I correct in assuming that some sort of adjustment to the values would make the range of the pot more useful? Like maybe I should put a couple of trim pots in place of the 150Ks and fiddle with them? Or would adding a ground resistor change that as well? (don't see how, but one can hope)
I'll give that a try.However, am I correct in assuming that some sort of adjustment to the values would make the range of the pot more useful? Like maybe I should put a couple of trim pots in place of the 150Ks and fiddle with them? Or would adding a ground resistor change that as well? (don't see how, but one can hope)
Re: Non-CF Clipper?
So imagine it like this--if the EQ cut from the tone control is currently a big ol' U shape, then putting a resistor between the whole thing and ground makes it more like a u-shape, shifted up.
Proportionally, you'll get "more mids", which means "less bass" and "less treble" (relatively speaking). This is where taking a 100k pot and wiring it as a variable resistor is a good bet. I imagine, though, a value between 10-15k will sound "fairly familiar" but you may find you like more.
Similarly, you can dink with the values of the .01uF cap. It functions not wholly dissimilar to the so-called "mid cap" in a typical FMV type tonestack. Changing the value doesn't so much give you more/less mids, but shifts where the scoop's center frequency is.
Also, this means that 250pF on top can be tweaked in much the same way a "treble" cap in an FMV stack does.
The "left" resistor in the T functions a lot like a "slope" resistor in the FMV stack. The "right" resistor is, yup, you guessed it- a lot like a fixed treble control.
The big question is what you want out of the tone control. For maximum versatility, something that effects the mids is the ticket. But if you don't want flexbility, fixing the amount of bass to pass and having the treble adjustable is a good idea.
Edit to include the following:
The 250pf resistor, consider a second 250pF in parallel to it on a switch for an upper-mid boost. (you can call it "snarl" if you want)
For the "treble" resistor, remember that it is in parallel with the "upper" portion of the tone control pot. I mentioned this above, but it's worth connecting the thought-dots. Using an FMV analogy, turning this control basically "turns down the treble knob while turning up the bass knob"- all the while, it's sweeping your mids. It's very, very flexible, and there are a ton of ways to limit it.
I'd challenge you not so much to worry about it's usefulness for the entire range of the control, but rather the number of sounds you can find in it. There are ways to limit the extremes (adding fixed resistors to the top of the knob comes to mind if you're finding the treble too robbed.)
Proportionally, you'll get "more mids", which means "less bass" and "less treble" (relatively speaking). This is where taking a 100k pot and wiring it as a variable resistor is a good bet. I imagine, though, a value between 10-15k will sound "fairly familiar" but you may find you like more.
Similarly, you can dink with the values of the .01uF cap. It functions not wholly dissimilar to the so-called "mid cap" in a typical FMV type tonestack. Changing the value doesn't so much give you more/less mids, but shifts where the scoop's center frequency is.
Also, this means that 250pF on top can be tweaked in much the same way a "treble" cap in an FMV stack does.
The "left" resistor in the T functions a lot like a "slope" resistor in the FMV stack. The "right" resistor is, yup, you guessed it- a lot like a fixed treble control.
The big question is what you want out of the tone control. For maximum versatility, something that effects the mids is the ticket. But if you don't want flexbility, fixing the amount of bass to pass and having the treble adjustable is a good idea.
Edit to include the following:
The 250pf resistor, consider a second 250pF in parallel to it on a switch for an upper-mid boost. (you can call it "snarl" if you want)
For the "treble" resistor, remember that it is in parallel with the "upper" portion of the tone control pot. I mentioned this above, but it's worth connecting the thought-dots. Using an FMV analogy, turning this control basically "turns down the treble knob while turning up the bass knob"- all the while, it's sweeping your mids. It's very, very flexible, and there are a ton of ways to limit it.
I'd challenge you not so much to worry about it's usefulness for the entire range of the control, but rather the number of sounds you can find in it. There are ways to limit the extremes (adding fixed resistors to the top of the knob comes to mind if you're finding the treble too robbed.)
Re: Non-CF Clipper?
Were you asking how a resistor in between where the tone is connected to ground and actual ground works to limit its effect? If so, I'll make a little blah. If not, well I did anyway. Have you ever wired up a tone network, and forgot to ground the mid pot? The tone net won't work, right? As it is, it has an unregulated straight shot to ground. By adding a resistor, it'll dampen its access to ground, thus work "less".
Out of curiosity, and laziness so I don't have to go searching, (I'm on my phone, it makes eveerything more difficult.) what are your coupling cap value(s)? As previously mentioned, they sound like they may be big. I used .0022's in my recent build and still have all the bass I need. Too much bass also makes me cranky.
Coupling caps are a big determiner of bottom end that passes. You could even just pop a small one in there to start, and if its too much loss, add a cap in parallel incramentaly by say 500pf at a time with alligator clips until you find the perfect value, and hardwire that size in. Or a treble peaker(s)? Again, I haven't looked at your schematic in a little while, not even sure how many stages you have, just spitballin idears.
Out of curiosity, and laziness so I don't have to go searching, (I'm on my phone, it makes eveerything more difficult.) what are your coupling cap value(s)? As previously mentioned, they sound like they may be big. I used .0022's in my recent build and still have all the bass I need. Too much bass also makes me cranky.
Coupling caps are a big determiner of bottom end that passes. You could even just pop a small one in there to start, and if its too much loss, add a cap in parallel incramentaly by say 500pf at a time with alligator clips until you find the perfect value, and hardwire that size in. Or a treble peaker(s)? Again, I haven't looked at your schematic in a little while, not even sure how many stages you have, just spitballin idears.
Re: Non-CF Clipper?
Thanks, both of you.
Matt - that's an excellent and detailed description and explanation of the CG. Now I know what to do with it.
Right now I have put a simple treble roll off in there. Btw, now two of my pots have bitten the dust. I replaced them with 1M pots which don't work so hot but they do allow me to play the amp. So I await the delivery of the several 500K units I have coming, one of them a PEC. know PECs are very nice pots and I wish I could afford to use them everywhere. But the budget says no, so I bought one anyway. Don't even know where I'm going to put it yet, but well there it is.
I did put 330pF 'bright cap' on the first stage's pot. That certainly stopped my complaining about it not being shiny enough at lower volumes. At any volume, really. Anyway, it's shiny now so the treble roller comes in handy.
However, when I get the proper pots back in there and fix up a CG adjusted the way I want it the bright cap will probably go. I do like the suggestion of another cap across the top on a switch; I have a switch that's wanting a purpose in life. It's labelled Platinum on top and Blonde on the bottom (Harlow).
I really like playing this amp even though it needs some tweaking. It's got a ton and a quarter of touch sensitivity. So it's really fun to play, you can do sooo much with it.
I'll keep progress posted along with clips when I get it to where I think it should be. Then I'll design a proper board for it so that when all those demands for one like it they will be easy to build.
Matt - that's an excellent and detailed description and explanation of the CG. Now I know what to do with it.
Right now I have put a simple treble roll off in there. Btw, now two of my pots have bitten the dust. I replaced them with 1M pots which don't work so hot but they do allow me to play the amp. So I await the delivery of the several 500K units I have coming, one of them a PEC. know PECs are very nice pots and I wish I could afford to use them everywhere. But the budget says no, so I bought one anyway. Don't even know where I'm going to put it yet, but well there it is.
I did put 330pF 'bright cap' on the first stage's pot. That certainly stopped my complaining about it not being shiny enough at lower volumes. At any volume, really. Anyway, it's shiny now so the treble roller comes in handy.
However, when I get the proper pots back in there and fix up a CG adjusted the way I want it the bright cap will probably go. I do like the suggestion of another cap across the top on a switch; I have a switch that's wanting a purpose in life. It's labelled Platinum on top and Blonde on the bottom (Harlow).
I really like playing this amp even though it needs some tweaking. It's got a ton and a quarter of touch sensitivity. So it's really fun to play, you can do sooo much with it.
I'll keep progress posted along with clips when I get it to where I think it should be. Then I'll design a proper board for it so that when all those demands for one like it they will be easy to build.