How to get better sustain, harmonics from clean channel?

[Tonegeek]

Anybody got any ideas on making the clean channel less clean? Put another way, I would like more sustain, sing, harmonic content, especially when I dig in. Currently I get a clear somewhat compressed, Fendery sound from my Strat on the clean channel. It is chimey on the top, slightly scooped in the mids with plenty of bottom. Sounds very good, just not what I need for my style. I have tried many combinations of treble (and a few mid) caps on this amp and have the tone I want, but not the crunch I desire. I want it to breakup more when pushed. I have tried cranking the vol up and clean master down, also tried different mid boost caps, but it does not have the desired effect as it sounds unnatural, if that makes sense. I actually get better results with OD on with no MID/PAB boost, and the drive dialed back, but then the tone is not quite right and that setting is unuseable when I go to all boost. Here's my setup:

HRM, 50w El-34, Marshall trannies (500r resistor instead of choke), BM PI, Skyline stack (324p treble, .01 mid), .01 V1b (CL2) coupler.
V1 and V2 Rp/Rk is 180K/3k3, 150K/2k2, 220K/3k3, 150K/2k2 with Ck of 5uF on all cathodes.
My V1 and V2 voltages at plates are 211, 207, 207, 213
PI plates are 278, 279 on feedback side.
built in Dumblelator always on

I am wondering if upping the first Rp to 220k will help. I have tried this in the past with no luck and always go back to 180k. The amp has recently been re-voiced and the gain structure altered (mostly in OD section) so maybe I need to try 220k again on the first plate.

I tried taking feedback from the 4 ohm tap but this gives me some spikey upper mids that I don't like. The whole amp is smoother sounding off the 8 ohm tap IMHO.

It seems like the gain structure and feedback is key to getting more sustain and harmonics with these amps. My OD channel is about where I want it and I realize any changes to clean will affect OD, but If I can get a harmonically richer clean sound then I would attempt to revoice OD to accomodate it.

[greiswig]

(SNIP) I am wondering if upping the first Rp to 220k will help. I have tried this in the past with no luck and always go back to 180k. The amp has recently been re-voiced and the gain structure altered (mostly in OD section) so maybe I need to try 220k again on the first plate

I thought increased voltage drop across Rp meant increased available P-P voltage out of that stage, i.e. going in the wrong direction for what you want? I could be completely wrong here, but have you tried lowering the cathode and plate values on V1 to something like the #124 values of 100k/1k5? Someone else with more know-how should chime in here and correct me if I'm wrong, please...

[odourboy]

Tons of interesting discussion on the topic on these threads:

https://tubeamparchive.com/viewtopic.php?t=3615

https://tubeamparchive.com/viewtopic.php?t=3839

[Tonegeek]

Tons of interesting discussion on the topic on these threads:

https://tubeamparchive.com/viewtopic.php?t=3615
https://tubeamparchive.com/viewtopic.php?t=3839

I reread these with much interest and it is helpful. thanks...

I thought increased voltage drop across Rp meant increased available P-P voltage out of that stage, i.e. going in the wrong direction for what you want? I could be completely wrong here, but have you tried lowering the cathode and plate values on V1 to something like the #124 values of 100k/1k5? Someone else with more know-how should chime in here and correct me if I'm wrong, please...

My experience is higher plate R = more gain. Its a bit counter-intuitive because there is actually less DC voltage at the plate with a higher value resistor. Reading the NEETS manual (module 6, I think) helped me understand how that works. I have tried 100k/ with various cathode values and it is too clean. I went back to 220k and this time I like it so for now it is staying at 220k. I am finally getting some warmth out of the clean channel. Also OD is giving up more harmonics and bloom so I am doubly pleased. Not sure why 220k did not work for me before, but there have been lots of changes to this amp since the spring so I have to revisit everything to make sure I am not missing something.

[butwhatif]

Lowering the cathode resistor value on V1a&b will decrease the bias on these two stages, and allow peaks to start to clip. 1.5 k is what I like, but lower will do more. Also, another solution is to place a series resistor after the coupling cap on V1b , experiment with values, even 220k to a few megohm can work-
the switching can be rerouted so that it's there for clean, and not in OD. Or if it sounds good in there for both, so be it. Increasing the pre volume will allow the V1b stage to be clipped harder for the same output volume level.