18W SuperLite TMB a little too harsh

[Piamp]

Hi!
Thanks for all the ressources here
I built a 18W SuperLite TMB, and i think it needs some tweakings.
I did not really like the gain/vol combination so i dumped the volume pot and wired a crossline master volume instead, it's much better now with nice PI distorsion.
But i find it a little too harsh, if no eye piercing....treeble needs to be way low even on the neck pickup of my LP.
Any tweak i could try ? A 50pf accross the pi did nothing
Also i get a lot of hiss, changed tubes, still here !

[thomas22]

Lower Coupling Cap Values – If you’re using 0.022µF or larger coupling caps in the preamp or PI, try reducing them to 0.01µF or even 0.0047µF to cut some of the high-end fizz.
Grid Stopper Resistors – Increase the grid stopper resistors on the preamp tubes, especially on V1 (try 68kΩ to 100kΩ on the input stage). This can roll off some high frequencies.

[Bieworm]

Hi!
Thanks for all the ressources here
I built a 18W SuperLite TMB, and i think it needs some tweakings.
I did not really like the gain/vol combination so i dumped the volume pot and wired a crossline master volume instead, it's much better now with nice PI distorsion.
But i find it a little too harsh, if no eye piercing....treeble needs to be way low even on the neck pickup of my LP.
Any tweak i could try ? A 50pf accross the pi did nothing
Also i get a lot of hiss, changed tubes, still here !

Let’s start with the speaker. If you’re using a V30 or G12H30 70th anniversary series that could be enough to experience a harsh amp. IME the SL is not a harsh amp at all

[Piamp]

I tried different speakers and it's the same feeling. The amp is loud (it should be) but also ear piercing in an unpleasant way.
There's a lot of gain and distorsion is very harsh and brutal.

I'v built others 18w and 50w marshall amps and it's the first time i get that feeling...
Only difference to the schematics is : no middle pot, replaced by a fixed 10k.

[JMPGuitars]

I'v built others 18w and 50w marshall amps and it's the first time i get that feeling...
Only difference to the schematics is : no middle pot, replaced by a fixed 10k.

If you want to rule that out, replace the 10k resistor with a 50k pot, and adjust.

[Piamp]

I tried the zener mod on the el84 grid leak resistors, well it went good, seems the ear piercing sound is alpost gone ; thats strange as i thought it was only usefull on distorsion sounds!

Tried a 300R resistor for more sag : it gets too hot !!!

[Bieworm]

I tried the zener mod on the el84 grid leak resistors, well it went good, seems the ear piercing sound is alpost gone ; thats strange as i thought it was only usefull on distorsion sounds!

Tried a 300R resistor for more sag : it gets too hot !!!

I never add sag resistors. The times I did I used 100R or 150R 25W resistors. The amp I'm currently building is a 6G16 with SS rectifier. I added a 100R 25W sag resistor bolted to the chassis to 'kind of' compensate for the feel of a 5U4 tube. It's important that the resistor can dissipate heat through the chassis. If it's air cooled it will merely handle 5 to 10W.