Making amp less bright

[pops]

Thanks for all the great replies. I was using a long cord, i typically run low preamp voltages as low as 105 for harp and slide guitar. Strings are damped behind the bridge, and have used a preamp to roll off the highs. A friend that plays slide has been trying to get a sound for years and we tried taking highs out of the guitar, but lost the bass sound he liked so we started taking highs out of the amp, switching tone caps for different sounds, 12AY7's, no bypass caps low voltages on the preamps and for guitar he is getting a great sound with the slide loosing the ice pick sound, but keeping highs in the bass and the sound he was looking for. May be shooting for something not easily attainable. The mandolin sounds good thru a P .A., but can get bright if too loud. Most others play thru their amp so sometimes a fight to play softer and hear in the monitors. I have tried several amps, but wanted to try this tube amp as it sounds good with out the pre amp, just a little bright. Going to open it up and see what i did if i can get time tomorrow. Sometimes i have used an .02mf on the tone control but don't remember what is there. Folks here have a lot of great ideas and i'm not remembering things these days like i used to. Thanks all i will let you know more when i open it up.

[Smokebreak]

The mandolin sounds good thru a P .A....

I built an amp for a fiddle player a while back, with 5F6A as a platorm. I got a lot of good help here, and some sound engineers chimed in on the frequencies they typically cut and boost in the front of house that were specific to fiddle. Turns out it was basically the opposite of guitar . I worked with the Duncan TSC and came up with a wacky tone stack that worked a treat. I put in a Cut too.
Anyways, that was obviously for a different instrument with different needs, but perhaps that route is another option.

[dinkotom]

but keeping highs in the bass

That's what caught my eye, how do you achieve this? With guitar's tone pot rolled down to where treble sounds good, the bass is too muddy, lME.

[pops]

Smokebreak, the fiddle and mandolin tune the same and have a lot of the same problems sound wise, with the fiddle maybe being even more temperamental. What was your weird tone stack.

dinkotom, we used 12AY7's thru the amp, no bypass caps this was a 5F6a and we used all 6v6's didn't need all the power and it was still loud, but warmer. lower plate voltages and if i remember .022 caps on the tone stack. I am sure there was more, but i don't remember we tweeked it for a long time. Tweek play out for a month tweek etc.

I am going to try and get it opened up today if all goes well.

[Structo]

What about using an equalizer pedal to fine tune the tone?

[pops]

Structo, yes i have used a preamp to tame the highs, but then the bass (what bass there is) gets this woof thing going on that i don't like and like my friend with the slide being bright if we took out the highs at the guitar the bass was not desirable so trying to warm up the amp to keep the tone control up so there is highs and clarity in the lows, but warmer highs. Like i said maybe it's not possible. Years ago i built an amp that National Guitars was going to market that really showed off the sound of the cone. It was really a harp amp, but worked well for the cone of the national. Looking to do something like that here.

[pops]

Well i opened it up this afternoon, didn't have a lot of time as i refretted my mandolin, different one, but i forgot i didn't build it for myself and had bypass caps on the preamp tubes. Disconnected those and changed the tone caps from 022 to 002, Leo got me thinking about the differences between harp and guitar and mandolin, and seems to work better. The woof part is when you pick the string if causes a lot of attack noise if there is not significant highs. I can turn the tone nearly all the way up now and it is ok bright wise. Disconnecting the bypass caps helped the lows a lot too. Thanks for all who replied, i will continue to tweek this as i get time.

[RWood]

I built a 5C3 which sounds real good with mando. The octal preamp tubes seem to be the difference.
The 5D3 with 12AY7 is too bright for mandolin but better for harp.
The 5E3 is not good for either.

[pops]

Yea, i built an octal valco based amp a few years ago that would have been great, but that has been gone a while, this one is here. Maybe have to build another octal.

[MHProd]

What's the OT primary impedance and what are the tubes? A pair of 6V6s?

[pops]

Pair of 6V6's, amp has single 12 so 8 ohms. Bought this and it was not working whoever made it did a terrible job and very unsafe so i ripped it apart and used the cab, chassis, tranny's and speaker and rebuilt it.

[stevehoover]

Two things that I have done on fender type circuit:
1. "Dark Switch" 680pf or so from V1 input grid pin to ground. (I put mine on a switch).
2. Simple Low pass filter (location and component values depends on which circuit you built). You can tune the filter to pass the frequencies that you want.

Both have worked for me on "bright" amps.
I have also used a Hi Pass RC filter on an overly Bassy circuit that bypass and coupling cap mods were just not right for.

I found a handy IOS app called AdaFruit Circuit Playground that has a RC filter calculator built in. Other useful stuff for builders as well, very handy app.
Cheers

[Smokebreak]

Smokebreak, the fiddle and mandolin tune the same and have a lot of the same problems sound wise, with the fiddle maybe being even more temperamental. What was your weird tone stack

Sorry pops, I lost track of this thread. I can't remember what the stack was, but I worked on the information in this thread https://tubeamparchive.com/viewtopic.ph ... p&start=45
I just started fiddling with the TSC until I got some curves I was looking for. I remember thinking it was opposite of what a guitar needs. Hope that helps. Next time I'm around the amp I'll make a point to look.

[pops]

[quote= Next time I'm around the amp I'll make a point to look.[/quote]

Thanks smokebreak i will look forward to it.