Making the treble control more effective?

[Bob-I]

I'm really pleased with this 100 Watt ODS HRM except for one thing, the treble control is simply too subtle. I can't make adjustments in highs like I'd like to.

Any thoughts on making the treble control more effective?

[Structo]

The treble control on the clean or OD stack?

I of course don't have a HRM yet, but I haven't ever been that impressed with the tone stack on these amps.
As usual a plate loaded stack only takes away so you always seem to lose something in a trade for this or that.

I've been wanting to experiment with a cathode follower stack, but that may be getting too far afield.

[Bob-I]

The treble control on the clean or OD stack?

Good question I was referring to the front panel tone stack so the global controls.

I of course don't have a HRM yet, but I haven't ever been that impressed with the tone stack on these amps.
As usual a plate loaded stack only takes away so you always seem to lose something in a trade for this or that.

Thing is, my Fender copies have far better range on the tone stack and they're plate load stacks as well. The big difference is the amount of mids pushed through. Changing to a Fender like stack would fix the treble control issue, but take away the Dumble character.

I've been wanting to experiment with a cathode follower stack, but that may be getting too far afield.

:

I also have a JTM-45/5F6-A type amp with a CF driven tone stack. At low gain levels it's very effective, but that decreases dramatically as you push the gain. Since it's just before the PI all the gain is in front of the stack. I know Dumble has made a big deal of the OD being after the preamp so if you were to do a CF-TS I'd recommend it comes before the OD stages.

This isn't an option for me though as I don't have any space for another tube.

[jelle]

The issue is the slope/taper of the 250K treble pot in your clean tone stack. Stick a Log in and you'll get the response back.

[Bob-I]

The issue is the slope/taper of the 250K treble pot in your clean tone stack. Stick a Log in and you'll get the response back.

Well I just tried that, it seems to have the reverse effect, now the treble does nothing until I hit about #7 on the dial, then it hits all at once.

[ChrisM]

You want more highs or you want the high control to do more?

Either way you can try lowering the treble cap.

[Bob-I]

You want more highs or you want the high control to do more?

Either way you can try lowering the treble cap.

I want more high control. I've tried 250pF, 330pF so I'll try 390pF and I'll see if I have a 470pF.

Thx

[ChrisM]

I would think you would want to lower it, not raise it.

You might try lowering your slope resistor a bit, if it is 150K. I have found the controls become more alive and do more when you drop the slope lower. The classic stack had 100K iirc.

[Bob-I]

I would think you would want to lower it, not raise it.

LOL... I was thinking lower the frequency not the cap, but pointing me at the treble cap was a good idea.

Actually raising the cap to a 470pF made the TS more effective, but operated the treble control at a lower range. I kinda like it.

You might try lowering your slope resistor a bit, if it is 150K. I have found the controls become more alive and do more when you drop the slope lower. The classic stack had 100K iirc.

Funny, I've read somewhere that raising the slope made the TS more effective. I've never tried that, cain't hurt.

[JD0x0]

you lose the high end control with the increased mids of the dumble tonestack. Scooping the mids will get you that control back. If you've ever noticed BF Fenders always have a huge treble range because the mid resistor (or pot) isnt usually over 15K where the skyliner mid pot is 250k.

[BobW]

you lose the high end control with the increased mids of the dumble tonestack. Scooping the mids will get you that control back. If you've ever noticed BF Fenders always have a huge treble range because the mid resistor (or pot) isnt usually over 15K where the skyliner mid pot is 250k.

Yes and the tone stack calculator illustrates this.

Bob, Although the tone stack calculator doesn't have a dumble circuit, using the fender ckt enables you to guesstimate the results on the dumble stack.

[Bob-I]

you lose the high end control with the increased mids of the dumble tonestack. Scooping the mids will get you that control back. If you've ever noticed BF Fenders always have a huge treble range because the mid resistor (or pot) isnt usually over 15K where the skyliner mid pot is 250k.

On the TSC if you just turn the mids down you can see the treble range increase, very cool.

[Structo]

I've played around on the TSC a bunch and it's a lot of fun.
I wish we could collectively ask Mr. Duncan to program the Dumble stack into the TSC, that would be cool to have it model a Skyline stack.

I'd do it if I knew anything about programming.
Don't we have a few software geniuses here?
Calling all haxers!

It has the C++ source code in the TSC folder if anybody wants to take a whack at it.

[Tonegeek]

I would think you would want to lower it, not raise it.

LOL... I was thinking lower the frequency not the cap, but pointing me at the treble cap was a good idea.

Actually raising the cap to a 470pF made the TS more effective, but operated the treble control at a lower range. I kinda like it.

You might try lowering your slope resistor a bit, if it is 150K. I have found the controls become more alive and do more when you drop the slope lower. The classic stack had 100K iirc.

Funny, I've read somewhere that raising the slope made the TS more effective. I've never tried that, cain't hurt.

I have been down this path and might be able to clarify a couple of things.
You didn't say if this was an issue in clean or OD mode. As you probably know the pre amp boost function defeats the stack. I will assume this is a clean or OD issue with boost not engaged.

The treble cap value determines where the highs begin to roll off. So going from a 250p to 470p is allowing some additional lower frequencies to be under control of the treble pot. You may percieve it as "more", but it is not more of the high stuff, its just got some upper mids mixed in now due to the larger cap. Changing to a log pot will not help anything as you found out. The taper just helps trick the ear into percieving a smooth transition from one setting to the next.

If you want more highs, you might think in terms of getting rid of some other frequencies to make the highs stand out more. If you have a .01 mid cap, try the .047 instead. This will have a more dramatic affect on the mids, which will make the highs (and lows) stand out more. Again, it will shift the rolloff of where the mids transition to bass to a lower frequency.

Lowering the slope resistor will make you have even less high end. I did this once and liked it for OD, but i was trying to tame some upper mid spike. It made the clean channel pretty flat sounding.

If this is a global issue, try bumping up the presence. You can experiment with the values as well.

You might try using the bright switch, especially for an HB equipped guitar. I think any value over 120p for the bright cap is useless though. Keep it small to start out.

What speakers are you using? I have G12-65's and while I like them a lot, I find they are a tad muted on the top end. This is great for OD, but a Fender afficianado may feel like something is missing.

Finally I will say that I did not like the Skyline stack in my HRM, but loved it in a low plate #124 I built. I converted my HRM to a BM with the .022 mid and bass caps and havent looked back. Still, it did not change the highs that much, but I really like where the frequency crossover points are in the BM stack. YMMV

[Bob-I]

I have been down this path and might be able to clarify a couple of things.
You didn't say if this was an issue in clean or OD mode. As you probably know the pre amp boost function defeats the stack. I will assume this is a clean or OD issue with boost not engaged.

It's global, and yes I know the PAB defeats the tonestack so it's really PAB off. I really like the PAB mode with OD the way it is.

The treble cap value determines where the highs begin to roll off. So going from a 250p to 470p is allowing some additional lower frequencies to be under control of the treble pot. You may percieve it as "more", but it is not more of the high stuff, its just got some upper mids mixed in now due to the larger cap. Changing to a log pot will not help anything as you found out. The taper just helps trick the ear into percieving a smooth transition from one setting to the next.

Yes, I checked out the TSC and it's really surprising how little difference the treble pot makes with the mid pot about about 20%.

If you want more highs, you might think in terms of getting rid of some other frequencies to make the highs stand out more. If you have a .01 mid cap, try the .047 instead. This will have a more dramatic affect on the mids, which will make the highs (and lows) stand out more. Again, it will shift the rolloff of where the mids transition to bass to a lower frequency.

Lowering the slope resistor will make you have even less high end. I did this once and liked it for OD, but i was trying to tame some upper mid spike. It made the clean channel pretty flat sounding.

If this is a global issue, try bumping up the presence. You can experiment with the values as well.

You might try using the bright switch, especially for an HB equipped guitar. I think any value over 120p for the bright cap is useless though. Keep it small to start out.

What speakers are you using? I have G12-65's and while I like them a lot, I find they are a tad muted on the top end. This is great for OD, but a Fender afficianado may feel like something is missing.

Finally I will say that I did not like the Skyline stack in my HRM, but loved it in a low plate #124 I built. I converted my HRM to a BM with the .022 mid and bass caps and havent looked back. Still, it did not change the highs that much, but I really like where the frequency crossover points are in the BM stack. YMMV

I've been thinking the same thing, but I noticed there's many other differences in the BM ckt, from the way the TS is wired to the PI.

Did you change all of these things or just the TS? I was thinking of trying this as well but I don't have a 15K pot handy, closest is 50K.

Right now I have a 100K slope and 250pF treble cap. I have a 3 way switch for bright, I have 2-100pF caps, center off, down 100pF up both in parallel so 200pF, very effective. The 100K slope didn't do what I'd hoped for.

Great info, thx.