"Cut" AND "Presence" knobs?

[dehughes]

Hello,

Again with the questions...

I'm thinking of putting both an AC30-ish Cut knob along with the stock Presence knob on a Blonde Bassman-ish creation I'm building. Would that be redundant? I'm not sure if it would ultimately be detrimental to the circuit (some things are best left un-tinkered with), but figured I'd ask in case someone has already done it.

Thanks.

[Andy Le Blanc]

it'll work to a point..... that kind of control seemed to be most apparent on an amp with
no feedback..... scab one in temporarlly with the amp on the bench to fiddle
with values..... and to see if you hear what your expecting.....

[dehughes]

it'll work to a point..... that kind of control seemed to be most apparent on an amp with
no feedback..... scab one in temporarlly with the amp on the bench to fiddle
with values..... and to see if you hear what your expecting.....

Ah, right....feedback. Thanks. I knew I was overlooking something. I don't know what I'd be expecting, but thought it might be yet another way to control the "clarity" of the amp, and perhaps work in conjunction with the conventional presence knob.

[CaseyJones]

I'm in the "less is more" camp. It's a matter of bein' decisive. Figure out how you want the amp to sound, make it so, end of story. If it were up to me I'd go Volume-Tone-period (the "period" is the pilot light, see?) and keep the tone control as low loss as possible.

Amps with 50 knobs and switches... many of them subtle or ineffective... are annoying.

[jaysg]

I put a Cut on my Liverpool. It works as expected.

[tomrasdf]

Two Rock uses both on their new amps (Classic and Overdrive Signature). Haven't had a change to mess with one yet, but it can't be terrible.

[leaveitalone84]

I put one on my express, also works as needed.

[Zippy]

I'm in the "less is more" camp. It's a matter of bein' decisive. Figure out how you want the amp to sound, make it so, end of story. If it were up to me I'd go Volume-Tone-period (the "period" is the pilot light, see?) and keep the tone control as low loss as possible.

Any favorite One-Knob tone controls that you might reference?

I was just having a conversation about this with RJ yesterday. There is so much talk of certain players always using the same setup that one wonders why they leave the knobs on the amp. (Yes, I know that it would take still some circuit elements to get the same response/shaping but why not go minimalist if you know what works?)

Thanks.

[iknowjohnny]

seriously...try this. i just finished a marshalesque hi gain amp and i used NFB and added a pot that is a variable NFB control. It acts very much like a cut but it's very effective. You can crank up the presense then counteract it's thin-ness and harshness with this control, and you end up with a very smooth compressed sort of tone. then back it all the way off and the compression and all are much less obvious. Between that and the treble and presence controls it is literally the most versitile marshall i ever had, even if it's not a marshall in name. the way it's wired is that you replace the 100k NFB resistor with a 50k pot in series with a 22k resistor. as you back the resistance down till the pot is out of circuit and you only have 22k between the loop and the OT tap, it's gets really smooth and compressed. I also added a switch to remove NFB altogether which give the exact opposite effect and makes for a very crunchy classic rock rhythm tones and a rich and in your face lead tone, especially when clean boosted.

Anyways, if you have NFB it's a simple 2 minute job to test it out. I'll tell you this....i owned a lot of marshalls and none were as versatile, nit by a mile. i can get any marshall style tone i've ever had out of this thing even with it being a single channel amp. .

[Andy Le Blanc]

Ive tried that in a few projects and found it to be very useable too......
Ive seen that approach published as an alternative to a fixed amount of NFB
in HiFi.......it gave my amp a texture control to the amp especially if the amp is to be
opperated cranked more than not.......

[iknowjohnny]

Thats a good word for it..."texture". It basically takes it from in your face crunchy to a more rockman sorta compressed smooth slightly blanketed tone. Thats pretty much allows to to truly mimic a lot of different amps. I can't get enough of this, and i only wish i'd had this sorta control when i was gigging still. But i didn't start building amps till after my gigging days were over.

[km6xz]

By adding variable FB, the gain of the amp, of course, changes, so setting of that control also require adjusting the gain to hear the "sound" of the control. I have added a dual ganged pot wired to another gain control that keeps the amp overall gain constant while changing the FB level. This way the actually tone change is heard easily instead of masking with by having a large volume change.
Note that FB also changes the dynamic damping factor and impedance of the amp. This changes the way the speaker interacts with the amp, which has a great effect on sound.

[dehughes]

Two Rock uses both on their new amps (Classic and Overdrive Signature). Haven't had a change to mess with one yet, but it can't be terrible.

I've played a Two Rock Classic Type 3 several times, and that is one of the best amps I've ever heard. I can't begin to tell you the options it has (oh, the switches!), but I'd like to keep this amp relatively simple. I'll have to ask my friend who owns that Two Rock what it's doing when he turns all those knobs (sure sounds great, though!). I think it has a "cut-ish" knob, as well as a presence equivalent...

[dehughes]

seriously...try this. i just finished a marshalesque hi gain amp and i used NFB and added a pot that is a variable NFB control. It acts very much like a cut but it's very effective. You can crank up the presense then counteract it's thin-ness and harshness with this control, and you end up with a very smooth compressed sort of tone. then back it all the way off and the compression and all are much less obvious. Between that and the treble and presence controls it is literally the most versitile marshall i ever had, even if it's not a marshall in name. the way it's wired is that you replace the 100k NFB resistor with a 50k pot in series with a 22k resistor. as you back the resistance down till the pot is out of circuit and you only have 22k between the loop and the OT tap, it's gets really smooth and compressed. I also added a switch to remove NFB altogether which give the exact opposite effect and makes for a very crunchy classic rock rhythm tones and a rich and in your face lead tone, especially when clean boosted.

Anyways, if you have NFB it's a simple 2 minute job to test it out. I'll tell you this....i owned a lot of marshalls and none were as versatile, nit by a mile. i can get any marshall style tone i've ever had out of this thing even with it being a single channel amp. .

Oh, now that's clever....very. Perhaps that'd be a neat option to a typical Cut control. Would that work just as well in a 6G6-B Bassman circuit, do you think? I'd like to be able to get the amp back to "stock", so I'd have to use a 25k pot and, say, a 33k resistor?

[Andy Le Blanc]

km6xz ....... has the right idea....... but keep in mind that this is not ment as
a "damping" control..... the application is not for "fidelity"....... I've had the
best results with a variable feedback control in amps that do not other wise
have much feedback...... with inverters other than chathode coupled long tail
with the control usually keep to a relatively small but critical range.......