Tone/Volume: need help to brighten things up

[MHProd]

Hi,

I hope everyone is safe and sound in those strange times we live in.

Over the years, I built several tweed and brown combos (5e3s, 6g2, 5d3, tweedledee or even a Marshall 18w). I’m not sure why, but all of them sound dark... the tone knob is always maxed out. I’m more of a plexi player, so me ears are used to brighter sounding amps I guess. I play with an amazing attenuator (Two Notes Torpedo Reload) so without full volume, I find the top end to be muffled quite a bit, especially with these amps.

In a Fender amp with traditional Tone/Volume arrangement, how can I increase the brightness? I added a presence pot to my 6g2 which helped, but I’d like to brighten the amps I have without NFB. I bumped the bright cap to 680pf, changed the tone cap to 1000pf... meh... I tried to add a 100pf cap to the volume but it didn’t do anything.

What else can I do while preserving the amp’s sound character? I think I tried a treble peaker a while back but I wasn’t a fan. It worked but denatured the sound too much...

Of course I tried different tubes and speakers. Tube rolling helped with getting better articulation in the highs but the impact is limited.

What mods would you suggest to achieve this?

THANKS!

[pdf64]

At high settings of their volume control, simple tone controls like those can only vary the degree of treble cut. They can only provide treble boost at lower vol settings.
Why not build a low power plexi?

[thetragichero]

decrease first stage cathode bypass cap? instead of 25uf try 1uf. if it's still not bright enough, try 100nf. if 100nf is too bright (which is likely) try 470nf it 680nf, whatever you have handy

[MHProd]

I thought about decreasing the first cap to a lower value, I think I had tried that but it mostly took low end away...

On these types of amps, why does adding a cap across the volume pot doesn’t do anything?

[brewdude]

I’ve been thinking about this kind of dilemma lately... I think if you want brighter, without reducing the bass response, what you might really want is mid scoop.

Merlin gives an example in one of his booksof a parametric mid control that I’ve been wanting to try.

[thetragichero]

On these types of amps, why does adding a cap across the volume pot doesn’t do anything?

depending on where you keep the volume level at the bright cap on the volume pot may have little to no effect

have you tried brighter speakers?

[ChopSauce]

Try a Celestion?

Have you read: https://ampgarage.com/forum/viewtopic.p ... 69#p420969
(try polypro caps)

Over the years, I built several tweed and brown combos (5e3s, 6g2, 5d3, tweedledee or even a Marshall 18w). I’m not sure why, but all of them sound dark... the tone knob is always maxed out. I’m more of a plexi player...

Didn't you simply found your limits?

Sometimes you can't change the nature of things. They just don't fit...

[statorvane]

Here is a cure for a dark sounding tone circuit: https://www.drtube.nl/schematics/marshall/2022.gif

I built one of these a couple of years ago, the 2061X version (different phase inverter). The 5nF (0.005 uF) treble bleed cap of the lead channel (middle tone/vol combination) can be very bright. Should tear your head off. I think the 1987 50 watt Marshall had the same value treble bleed cap.

Here's a demo (go to about 4:40 to hear it in action). https://www.youtube.com/watch?v=JAajlPABSHA Amp vol was on 1 for the demo. I suspect tone was max.

[JD0x0]

Are you sure it's not your attenuator taking off highs, coupled with compression from having the amp cranked up? You mention all your builds seem to sound dark, and you use an attenuator with them. I know some attenuators, like Weber, have 'bright' switches on the attenuators themselves to compensate for losses.

[jcool666]

On these types of amps, why does adding a cap across the volume pot doesn’t do anything?

The tweed-era tone control already has a bright cap built into it. The wiper of the tone pot sweeps between a treble bleed cap and a bright cap. If you add another bright cap to the circuit, it just lowers the frequency threshold for what bypasses the volume control. Have you tried going lower on your coupling caps? Maybe 10 or even 5 nanos?