PI Plate Voltages

[Charlie Wilson]

Thanks JC, I had to look at your original post to see how the switching works for the middle ON position but I like the idea.
CW

[martin manning]

It's your idea jc, I just made a neater layout. ;^)

[jcsifu]

It's your idea jc, I just made a neater layout. ;^)

Well...mine was ugly and yours is perty

[jcsifu]

Thanks JC, I had to look at your original post to see how the switching works for the middle ON position but I like the idea.
CW

Sorry Charlie, I meant to post the switch "description" pics from that post. I think it will work well for you though.

BTW
I used 330pF and 620pF (500 + a 120). This seems to accentuate the 1250hz frequencies since I was looking to add some honk/nasal tone character to the amp.

[bluesfendermanblues]

....Eventually you end up with a pile of amps that sound the same - if you're not careful.......
....

True that! My amps - Low Plate Classic, #102 and #183 - sound more or less the same in a band situation. The smaller differences are not really noted or appreciated by my band mates or the audiences - I usually just get a 'sounds great'. However, I can hear the small variations in the amps and and settings and it gives me a cork sniffers thrill to play a Stradivarius amp - usually without additional effects - (my pedal board with a Zen is for jams on generic backline amps). When I play the one of the amps in clean mode (and I really love that clean sound) during choruses, I feel excitement and expectation building up inside - and great pleasure once I hit the OD bottom and start wailing.

However, from an audience perspective the amps probably sound very alike with a solid focus on the mids - so I probably have a pile of amps that sound the same....from an audience perspective .

[Charlie Wilson]

I just one amp to sound good.
CW

[stelligan]

I just one amp to sound good.
CW

Get off the forum already. You need at least 5 that sound good after months of festering, then no more room in your domicile to pile them up........

[67plexi]

Charlie Just one good amp come on that's like saying I just want one good woman
it will never happen. I honestly try to limit myself two build per year.
Some Helpful advice is after you mod your amp give it a few weeks to settle in.
As far as adjusting the PI I set it at 6 volts differential mark it then with a plastic screwdriver play a guitar
and fine tune it. The guitar is grounded so only use one hand in the chassis and don't touch the guitar
when adjusting the PI trimmer. I only have 14 amps with a PI trimmer my preference is in the 6.3 volts range.
Like 298 volts and 291.7 volts as a example.

Steve.

[Luthierwnc]

What's worse, you can fiddle with an amp that sounds great trying to make it sound perfect. After doing that a few times, I realized I wouldn't know perfect if I heard it. Better just build another amp. sh

PS, kebob skewers from the grocery store, whittled on two sides make a quick and non-conductive screwdriver for small, hard-to-reach, hazardous locations. Good glue mixers too. Buck and a half for a bag of 80.

[CHIP]

It's been said a lot of times on this forum - build one of the documented designs and then again let your ears decide your tweaks - after a lot of play-in time.

Sage advice. We all end up wanting to sound like ourselves - like we want, in a way. Getting an amp there takes longer with some builds than others. Eventually you end up with a pile of amps that sound the same - if you're not careful.......

To the PI point - my best result is around 6v difference then listening for best sustained tones on the unwound strings near the nut. D cowboy chord area. Seems that the PI adjustment mostly impacts sustain elements rather than timbre for me....

I do believe some players end up sounding like themselves whatever they play through.
Keith Richards said something along the lines of , Give me any amp and within a short time I'll make it sound like me.

[Charlie Wilson]

Whoa, I guess I touched a nerve on the one amp thing. I really enjoy building and have plans to build other circuits(2nd gen. 50w,#183,SSS!?) and yes I have been messing with this circuit for too long but I think all the stuff I have learned with this one amp will carry over to other builds. Actually the amp does sound good it's just the treble thinness was bugging me a bit and I think the mid boost idea and a good PI tube that seems to like voltages higher than what seems usual for this circuit were the final pieces of the puzzle. I agree that the different circuits sound different and should be taken for what they are but on the other hand I absolutely refuse to stop working on an amp until I can take it to a gig and have a good night. I think I have a handle on the PI plate voltage differential and trimmer I was just wondering if anybody seemed to prefer overall higher PI plate voltages. I tried the bamboo sticks but my trimmers are a little tight and they kept breaking off at the tips. I use the plastic TV trim adjusters. They are a little short but my hands are no more closer to the bad stuff then when I use the probes of my multi meter. The funny thing about Keith Richards is he does sound the same no matter what he plays through but he seems to have 20 amps on stage when he plays. Steve I am still looking for one good woman but if I find her she better like amplifiers.
CW

[jcsifu]

I was just wondering if anybody seemed to prefer overall higher PI plate voltages.

Charlie,

I dropped my PI voltages down 10 below spec on my #124 inspired low plate skyline for a while. I thought it might bring a type of harshness I was trying to get rid of to a halt. The biggest change I can report is it seemed to be creating a clean tone that is more usable for me. I swear it was fatter. I think the drop also made the OD tone richer. I don't know how this would work, but I feel like the sound spectrum was made narrower, so a slight bit less highs and lows pass. Not saying thats true....just trying to say what I heard.

jc

[Charlie Wilson]

JC, interesting. So you dropped them to say 270v and 280v(approx.)? Maybe less gain, less frequency spread. I think I want to accomplish the same thing your were going for, so I am going to play around with that a little using the same tube. Now I noticed you said "for awhile", does that mean you went back to the original voltages you had?
CW

[jcsifu]

JC, interesting. So you dropped them to say 270v and 280v(approx.)? Maybe less gain, less frequency spread. I think I want to accomplish the same thing your were going for, so I am going to play around with that a little using the same tube. Now I noticed you said "for awhile", does that mean you went back to the original voltages you had?
CW

Yes, 273 and 281 were the readings taken.

It is still in that config, I should say that I made another change after "awhile" and now would not be able to have the same sound as before. I started trying out different presence cap types. I wanted to be able to turn up the presence and get more from the NFL from the output tranny. I was thinking if I had a dull sounding presence cap type in there, I could use more on the knob and not make it sound too ice pick highs. I used a 50v panasonic (CG) I think stacked metal cap and found it made a difference.

Anyway, that is why I said for awhile. I really do have something wrong with me as I can't stop working on my amps to make em....better.