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Tone Stack Clunk: Opinions please?

3/4/2000 2:34 AM
Gil Ayan	Tone Stack Clunk: Opinions please? Well, the first thing to do would be to start by describing what I mean by the clunk. Finally, a good friend of mine understood what I meant and defined it by "the attack of the pick which precedes a note when you pluck it." And it is what I was referring to. Let me try to explain the background of this issue, and then I'd love to hear about your experiences in this area. As most of us have done at this point, I have toyed a lot with after overdrive tone stacks and I have a couple of amps with them and one without. The benefits of having the post OD TS do exist, since it allows to tailor the sound of the overdrive to a great extent, and if you don't have a post OD TS, you're at the mercy of the amp so to speak. However, the more I listen to the amps with the post OD TS, the more I hear the clunk. The disadvantage of that bassy attack of the pick is that it's as though the amp wanted you to hit the notes hard. Digging in proggressively form very soft to very hard is not as good as when the extra TS is not there; without the TS, the attack of the amp seems to be a lot more responsive to the pick. In general, I guess one could say that Fender types of amps don't have a clunk to speak of, whereas Marshalls tend to have it. The infamous clunk is one of the reasons I never used the graphic EQ in my old Mesa Mk IIC+, because it felt unnatural on the bottom end. I have found that by dialing up the midrange control -- hence diminishing the effect and loading of the TS -- the clunk tends to decrease, but that kind of defeats the point of having the post OD TS in the first place. So, my quesion to you is whether you have noticed this phenomenon before, and if you have, whether you have come up with any work arounds for it. Cheers to all, Gil

3/4/2000 2:34 AM

Gil Ayan

Tone Stack Clunk: Opinions please?

Well, the first thing to do would be to start by describing what I mean by the clunk. Finally, a good friend of mine understood what I meant and defined it by "the attack of the pick which precedes a note when you pluck it." And it is what I was referring to. Let me try to explain the background of this issue, and then I'd love to hear about your experiences in this area.

As most of us have done at this point, I have toyed a lot with after overdrive tone stacks and I have a couple of amps with them and one without. The benefits of having the post OD TS do exist, since it allows to tailor the sound of the overdrive to a great extent, and if you don't have a post OD TS, you're at the mercy of the amp so to speak.

However, the more I listen to the amps with the post OD TS, the more I hear the clunk. The disadvantage of that bassy attack of the pick is that it's as though the amp wanted you to hit the notes hard. Digging in proggressively form very soft to very hard is not as good as when the extra TS is not there; without the TS, the attack of the amp seems to be a lot more responsive to the pick.

In general, I guess one could say that Fender types of amps don't have a clunk to speak of, whereas Marshalls tend to have it. The infamous clunk is one of the reasons I never used the graphic EQ in my old Mesa Mk IIC+, because it felt unnatural on the bottom end.

I have found that by dialing up the midrange control -- hence diminishing the effect and loading of the TS -- the clunk tends to decrease, but that kind of defeats the point of having the post OD TS in the first place.

So, my quesion to you is whether you have noticed this phenomenon before, and if you have, whether you have come up with any work arounds for it.

Cheers to all,

Gil

3/4/2000 7:30 AM
Carl B.	Gil, I've an "after over-drive" tone stack in my Rail-Rocket prototype, and it doesn't seem to give the kind of behavior that you describe. First-off, this is kind of a special over-drive: It's Stephen Delft's Moonlight OT and output stage with an early Marshall style preamp. After that "mid-stage," a bit of immediate filtering is done, and then into a 12AX7 that drives the tone stack. Hmmm. The values of the tone stack are no-where near standard, so that's yet another point of departure from your setup. For what it's worth, you can check it out over on the AX84 board under the Rail-Rocket project. Schems are there, that reminds me: I've got to get off my duff and do a few updates to those! - Carl B.

3/4/2000 7:30 AM

Carl B.

Gil,

I've an "after over-drive" tone stack in my Rail-Rocket prototype, and it doesn't seem to give the kind of behavior that you describe.

First-off, this is kind of a special over-drive: It's Stephen Delft's Moonlight OT and output stage with an early Marshall style preamp.

After that "mid-stage," a bit of immediate filtering is done, and then into a 12AX7 that drives the tone stack.

Hmmm. The values of the tone stack are no-where near standard, so that's yet another point of departure from your setup.

For what it's worth, you can check it out over on the AX84 board under the Rail-Rocket project. Schems are there, that reminds me: I've got to get off my duff and do a few updates to those!

- Carl B.

3/4/2000 6:34 PM

Trace

quote:
"In general, I guess one could say that Fender types of amps don't have a clunk to speak of, whereas Marshalls tend to have it."

I'm not sure what values you are using for the tone stack Gil or what circuit you have before the tone stack so if this seems a bit vauge I apologize! (ha, ha)

I do belive know what you mean when you refer to the "clunk" in amps. I belive it's the bass that comes with the pick attack(?) Assuming this is what you are talking about (correct me if I'm wrong Gil) and just dealing with the differences between Fender and Marshalls I would say try this;

1.) 500pF treble cap to 680pF treble cap.
2.) Make sure the other caps are both .022's and not the .1 and .047 values (at least for now)
3.) Install a 100K audio taper pot in place of the 33K slope resistor. Put the 33K on the bottom side of the pot so you can sweep between 33K to 100K.

SLOPE RESISTOR:
I think you will find that when you are at the 33K you will hear more of the "thunk." When you get twords the center of the pot the "thunk" goes away. I think this is in and around 56K or so but you can meter the pot once you find the sweet spot.

Now for my silly way of hearing tone stacks (ha, ha) I think the .1/.047 (fender/boogie) values set you up for too much low-end and it works well when you use a 100K slope resistor but the thunk becomes present when you get around 56K-33K with these cap values.

People favor the older Fenders and they say they are "smoother" on th low-end but then again they used either a pair of .022's or a .1/.022.

The treble cap also will control how much "umph" (for lack of a better word--ha, ha) that goes to the treble pot and of course to the rest of the EQ (so does the slope resistor). I think that the balance you are looking for can be found mostly in the treble cap and the slope resistor combos, assuming the other caps are .022's. (again, for the sake of this post)

For whatever it's worth Gil, I like a 500pF-680pF treble cap, 56K/47K slope resistor and a pair of .022 caps. The treble cap is usually ceramic. Thi is sort of "general" but it mostly depends on what amp/circuit we are talking about.

I think if you wire the variable slope pot you will really hear where the thunk is and it's ALOT easir to find the right value for each amp.

Hope it helps a little;
Trace

I think you can dial out the thunk

The infamous clunk is one of the reasons I never used the graphic EQ in my old Mesa Mk IIC+, because it felt unnatural on the bottom end.

I have found that by dialing up the midrange control -- hence diminishing the effect and loading of the TS -- the clunk tends to decrease, but that kind of defeats the point of having the post OD TS in the first place.

So, my quesion to you is whether you have noticed this phenomenon before, and if you have, whether you have come up with any work arounds for it.

3/4/2000 7:58 PM

Gil Ayan

Trace: Right on The Money -Tone Stack Clunk: Opinions please?

quote:
"I'm not sure what values you are using for the tone stack Gil or what circuit you have before the tone stack so if this seems a bit vauge I apologize! (ha, ha)"

No problem.

I have a Humble preamp and the TS had the values you mentioned, .022uF caps, 500pF treble and 33K slope.

quote:
"I do belive know what you mean when you refer to the "clunk" in amps. I belive it's the bass that comes with the pick attack(?)"

Right you are, Trace.

quote:
"SLOPE RESISTOR:
I think you will find that when you are at the 33K you will hear more of the "thunk." When you get twords the center of the pot the "thunk" goes away. I think this is in and around 56K or so but you can meter the pot once you find the sweet spot.
"

I will try that and report back.

quote:
"Hope it helps a little;
Trace
"

Thanks very much, Trace.

Gil

3/5/2000 1:42 AM
Paul C	Well, I never get around to posting much anymore, but there's an idea I've been wanting to work on but not had the time. Since there seems to be qualities of pre and post distortion tone stacks that are good and bad I've been wanting to play around with having both in an amp, but only having one set of controls on the outside. Maybe something like the bass control from the pre dist TS to control low end before the distortion craps out, and the mid and treble control from the post distortion TS to control all the hi freq harmonics/noise coming from the distortion process. Have trims on the board to set the range/tone of the controls on the outside. I remember seeing a few amps like some boogies that have a preset tone stack in the amp, but I think that you could pick each control for the face plate from the section that has the best responce for the job. Been done?

3/5/2000 1:42 AM

Paul C

Well, I never get around to posting much anymore, but there's an idea I've been wanting to work on but not had the time. Since there seems to be qualities of pre and post distortion tone stacks that are good and bad I've been wanting to play around with having both in an amp, but only having one set of controls on the outside. Maybe something like the bass control from the pre dist TS to control low end before the distortion craps out, and the mid and treble control from the post distortion TS to control all the hi freq harmonics/noise coming from the distortion process. Have trims on the board to set the range/tone of the controls on the outside. I remember seeing a few amps like some boogies that have a preset tone stack in the amp, but I think that you could pick each control for the face plate from the section that has the best responce for the job. Been done?

3/5/2000 3:43 AM
Gil Ayan	Update Since I had an extra TS board lying around, I tried using it in the FX loop of the amp that doesn't have the post OD TS. No doubt about it, the TS introduces the dreaded clunk there as well, and what's more, no matter how one sets the controls, the sound is inevitably "more Marshall" tahn without it. Yes, the vocal quality goes out the window and the sound crunches... Now this is not a bad thing, but it is what it is. I suppose I could make TS boards that have a little switch to lift the gorund of the TS, disabling it, so as to have the option of which way to go. Haven't played with the slope resisotr, that comes tomorrow. :/ Gil

3/5/2000 3:43 AM

Gil Ayan

Update

Since I had an extra TS board lying around, I tried using it in the FX loop of the amp that doesn't have the post OD TS. No doubt about it, the TS introduces the dreaded clunk there as well, and what's more, no matter how one sets the controls, the sound is inevitably "more Marshall" tahn without it. Yes, the vocal quality goes out the window and the sound crunches... Now this is not a bad thing, but it is what it is. I suppose I could make TS boards that have a little switch to lift the gorund of the TS, disabling it, so as to have the option of which way to go.

Haven't played with the slope resisotr, that comes tomorrow. :/

Gil

3/5/2000 6:44 AM
Steve A.	Gil: I remember this being mentioned a few times last summer, but has anybody tried inserting a "tweed style" tone control after the OD section? "Tweed" as in a 5F2-A Princeton with the .005uF cap to ground on the CCW end of the 1M tone pot and the 500pF cap on the CW end wired as a "bright cap" to the 1M volume control. I believe that the values would need to be adjusted to match the impedance and voltages involved and to tune the filters to work better with the OD sound. There is much less loss through a circuit like that than with a "real" 3-pot tone stack. A control like this could probably be mounted on the front panel so that you could dial in any sound from too bassy to too bright... < grin > --Thanks! Steve Ahola P.S. It would also be interesting to plug a graphic or parametric equalizer into the FX loop of a Skyliner minus the post OD tone stack just to see what frequencies we'd have to boost or cut to get some really nice sounds (like the elusive Gerald Ford Skyscraper sound).

3/5/2000 6:44 AM

Steve A.

Gil:

I remember this being mentioned a few times last summer, but has anybody tried inserting a "tweed style" tone control after the OD section? "Tweed" as in a 5F2-A Princeton with the .005uF cap to ground on the CCW end of the 1M tone pot and the 500pF cap on the CW end wired as a "bright cap" to the 1M volume control. I believe that the values would need to be adjusted to match the impedance and voltages involved and to tune the filters to work better with the OD sound. There is much less loss through a circuit like that than with a "real" 3-pot tone stack.

A control like this could probably be mounted on the front panel so that you could dial in any sound from too bassy to too bright... < grin >

--Thanks!

Steve Ahola

P.S. It would also be interesting to plug a graphic or parametric equalizer into the FX loop of a Skyliner minus the post OD tone stack just to see what frequencies we'd have to boost or cut to get some really nice sounds (like the elusive Gerald Ford Skyscraper sound).

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