Frequency focus shift? - harsh tone I'd like to fix

[mlp-mx6]

OK folks, I've been tweaking this amp a bit (or trying to), and things are better, but I'm still very frustrated with my current non-HRM build.

It's as if the "center frequency" of the amp, and especially of the distortion, is too high, into the upper mids. If you listened to Dogears' "DumbleTone" mp3 you'll hear an amp where I would say the focus of the entire tone is pretty low-mid to my ears. My amp is currently much "sharper" or "harsh" sounding. You know how some amps make your ears hurt at a lower volume because there is some kind of harshness in the tone, while others can be louder than that but still not hurt your ears? I'm going for the not hurt, but my amp is in the hurt zone right now.

Any ideas how to shift this around? I will build another amp that is non-HRM, but I want to leave this one as a non-HRM, so please don't suggest to change this one to HRM (grin).

CL1 - 180K plate, 10uF & 2.7K, tone stack output like ODS101
CL2 - 120K plate, 10uf & 1.8K, .047 output
extra .047 in series with CL2 .047 output cap for OD mode
OD1 - 180K plate, 4.7uF & 2.7K, .01 to 100K to drive pot (100K)
OD2 - 120K plate, 4.7uF & 1.8K, .0056 to 150K to OD level pot (100K)

This is basically an ODS101 non-HRM preamp with tweaks for 180K-120K-180K-120K plates.

Any suggestions to warm this up, make it sweeter and less strident?

[odourboy]

OK folks, I've been tweaking this amp a bit (or trying to), and things are better, but I'm still very frustrated with my current non-HRM build.

It's as if the "center frequency" of the amp, and especially of the distortion, is too high, into the upper mids. If you listened to Dogears' "DumbleTone" mp3 you'll hear an amp where I would say the focus of the entire tone is pretty low-mid to my ears. My amp is currently much "sharper" or "harsh" sounding. You know how some amps make your ears hurt at a lower volume because there is some kind of harshness in the tone, while others can be louder than that but still not hurt your ears? I'm going for the not hurt, but my amp is in the hurt zone right now.

Any ideas how to shift this around? I will build another amp that is non-HRM, but I want to leave this one as a non-HRM, so please don't suggest to change this one to HRM (grin).

CL1 - 180K plate, 10uF & 2.7K, tone stack output like ODS101
CL2 - 120K plate, 10uf & 2.2K, .047 output
extra .047 in series with CL2 .047 output cap for OD mode
OD1 - 180K plate, 4.7uF & 2.7K, .01 to 100K to drive pot (100K)
OD2 - 120K plate, 4.7uF & 2.2K, .0056 to 150K to OD level pot (100K)

This is basically an ODS101 non-HRM preamp with tweaks for 180K-120K-180K-120K plates.

Any suggestions to warm this up, make it sweeter and less strident?

Not sure if this is your problem, but the CL2 and OD2 cathode resistors should probably be 1.8K, NOT 2.2K.

Also, ideally, the .047s should be 6PS .05s and the .0056 should be a 6PS .005.

Another big challenge is going to be to try and get that DumbleTone HRM sound out of a non-HRM build.

[mlp-mx6]

Not sure if this is your problem, but the CL2 and OD2 cathode resistors should probably be 1.8K, NOT 2.2K.

Also, ideally, the .047s should be 6PS .05s and the .0056 should be a 6PS .005.

Another big challenge is going to be to try and get that DumbleTone HRM sound out of a non-HRM build.

Thanks for the reply. I had forgotten to switch those cathode resistors - thanks for catching that.

I know the spec is for .05 but .047 is within the tolerance of the given caps, and it is what I had (same for .0056). When I order caps again I'll get the other parts. I can hardly believe, though, that such a tiny difference in the values could cause such a significant difference in the tone. Every cap I used above pF sizes is 6PS, without exception. All pF sizes are ceramic.

Uh, I thought I had already mentioned the HRM thing. I realize that the particular clip I referenced was an HRM amp, but non-HRM amps can have the lower "focus freq" that I mentioned. I'm not sure if Robben's earlier recordings were HRM or not (especially RF&TBL, which is MY target tone), so the point I was trying to make was that a good, clear, full, warm tone should be possible with non-HRM also. Do you disagree? The point of referencing that clip was as an example of the lower frequency focus, not HRM vs. non-HRM. Again, I am NOT striving for HRM tone from a non-HRM amp.

[odourboy]

Uh, I thought I had already mentioned the HRM thing. I realize that the particular clip I referenced was an HRM amp, but non-HRM amps can have the lower "focus freq" that I mentioned. I'm not sure if Robben's earlier recordings were HRM or not (especially RF&TBL, which is MY target tone), so the point I was trying to make was that a good, clear, full, warm tone should be possible with non-HRM also. Do you disagree?

Not at all. I just wanted to mention that if you were trying to totally nail that clip tone, it might be somewhat elusive with a non-HRM.

BTW, check your PM - I have a question for you about your build.

Cheers! OB.

[dogears]

Hey Mike,

Get those cathode resistors lowered. It will help.

Also, what pups are you using?

Speaker?

I found that the wrong speaker can really scrww stuff up. Same with pickups.

If I were you, I'd build me an HRM!!! It does that tone. Not the non HRM.

[Bob-I]

Hey Mike,

Get those cathode resistors lowered. It will help.

Note that the cathode RC network cutoff point will be affected by changing either of the components. Dropping this 2.2 to 1.8 will make a difference

If I were you, I'd build me an HRM!!! It does that tone. Not the non HRM.

You can use this amp and make some changes. OD entrance, plate/cathodes plus adding the HRM board which rides above the main board. Not rocket surgery, but very effective.

[mlp-mx6]

Thanks, folks.

My NEXT build will be an HRM amp. (I'm debating whether to build that one as a 50W or a 100W. I don't have a 100W amp.)

I have lowered the cathode resistors per the suggestion, but have not had a chance to turn the amp on yet - July 4th plans. (I had mistyped the CL2 & OD2 cathodes, they were the correct 67-1 ratio 1.8K. Earlier post is corrected.) The other values were a mistake on my part, not intentional. I had varied the plate resistors earlier and thought I had changed the cathodes also, but perhaps I was called away to dinner and forgot.

Humbucker pups are Vintage 50s - PAF equivalent. I have a hardtail Strat with Fralins, and a regular Tele with "Broadcaster" pups. The pups are fine. Speaker is NOT what I'd like to be using, but my other "TDS" amp sounds better than this one does now. It does not have that harsh upper-mid thing going, and is actually pretty close to that reference tone mentioned as far as smoothness goes. I will be getting a 2-12 G12-65 cab, but not just yet.

[mlp-mx6]

Only one change so far, and that was to correct the cathode resistor values on CL1 and OD1. Just that change has made a HUGE difference in the overall tonality. There really IS magic in that "magic ratio" of 67-1 for plate resistor to cathode resistor.

I have a couple other tweaks to try, but I'm already much more pleased with the tone and response.

Thanks to all!

[Bob-I]

Only one change so far, and that was to correct the cathode resistor values on CL1 and OD1. Just that change has made a HUGE difference in the overall tonality. There really IS magic in that "magic ratio" of 67-1 for plate resistor to cathode resistor.

I have a couple other tweaks to try, but I'm already much more pleased with the tone and response.

Thanks to all!

dogears says it all the time, start with the known good values and you'll have a great sound right off the bat. Then you can tweak from there.