Basic Tone Circuit Changes

[roadshow]

Hi Guys,

I wanted to get more treble out of my standard tone circuit, what is the best way to do this? The first attachment is the way it is today, pretty much standard. I'm sure a TMB would have been the way to go to begin with, but it is what it is at this point.

What can I try? Change the 10nF or 4.7nF caps? Change the 100k resistor?

What about changing the circuit to the way JMP has the EF86 Lite? If I did, what changes could I work with?

Thanks

Mojo-Tone.jpg

JMPGuitars_18_Watt_EF86-tone ckt.jpg

[JMPGuitars]

You can lower the 100K resistor. Try any value between 33K up to 100K. 33K should give you more gain and treble. (see Richie's tweaker table - that resistor is the same as R1: storage/18_Watt_TMB.pdf )

What speaker are you using?

Thanks,
Josh

[roadshow]

Thanks Josh,
I'll try that. This is the build from earlier this year, a couple of WGS speakers:

Bill

14 Assembled Front.jpeg

13 Assembled rear 2.jpeg

[geoff 1965]

hello Bill,
do me a favour and post your results with this tweak,i have the lite2b circuit which is your normal channel but with the tremolo tonestack and i'm considering changing to the normal tonestack.

[roadshow]

Sure,

Give me a couple of days to make some audio files...

[roadshow]

Well,

I made the prescribed changes, and dropping the 100k down to 50k and the 33k may have affected it slightly, but at full turn on the pot it actually dropped the volume slightly, so I went back to 100k. I tried recording the differences, but the only set up I have is into a mic input into a PC and the differences were not evident.

In a nut shell, here's my conclusion. My expectation just may not be reasonable. I'm expecting to hear full brightness like I get with my JTM45, H&K GM36, TRRI, etc., but I think I'm realizing that such isn't possible with this tone control only 18 watt'r. And that's OK, I discovered when I put my Bad Monkey in front of it I can get exactly the tone brightness I want!!

I have a couple of other issues to move onto with the amp when time permits, but that's for a different thread.

Bill

[JMPGuitars]

I'm expecting to hear full brightness like I get with my JTM45, H&K GM36, TRRI, etc., but I think I'm realizing that such isn't possible with this tone control only 18 watt'r.

Question: have you tried any of those amps through the speakers in that cab (and I do mean IN that cab)?

The biggest tone curve change is usually the speakers. 18 watters are typically considered bright amps, so if you don't think it's bright enough, that's where I would look.

[roadshow]

Actually, yes.

Earlier this year when I was solving the motorboat issue and the cabinet was finished, I had the H&K GM36 sitting on top and was using it to drive those speakers. Sounded great.

[crgfrench]

I wish WGS didn't have that nonsensical "rationale" for refusing to publish frequency response charts. I bet a pair of Celestion G10M greenbacks would brighten up your sound in that amp.

[roadshow]

@Josh,

Because of the discussion "First post, my “new” 18W",

What about the tone circuit in the 18W Lite II? Arranged a little differently and minus the 100k...

The rest looks like the standard 18W, so is that worth a shot for brightness?

[JMPGuitars]

@Josh,

Because of the discussion "First post, my “new” 18W",

What about the tone circuit in the 18W Lite II? Arranged a little differently and minus the 100k...

The rest looks like the standard 18W, so is that worth a shot for brightness?

Yeah. If you're not happy with it, it's obviously worth trying other things for the tone stack. You could probably also try a 5E3 tonestack too if you're willing to take the time to figure it out.

[roadshow]

So,
I have tinkering plans coming up for the 18W I built a few years ago, and one of the things I wanted to get back to was the tone circuit. Searching for a tool that possibly already supported the 18W tone stack I wound up at circuitlab.com. (Duncan labs Tone stack calculator is nice, but only has Marshall TMB and not 18W tone.)

Any of you guys been to this site? If so, do you like it?

Anyway, a couple of observations changing the values to achieve the results I was after by graph, C2 as shown in the picture below had the biggest effect, not R1 or C1.

See the short form table I put together from the graph outputs.