Ultraphonix adventure

[Guy77]

Very nice AC DC tones. Congrats.

G.

[Synchu]

One can definitely hear the potential Thanks!

I’ll breadboard the pre and maybe also make a SE version of it for the sake of the experiment
I have a vintage 74 100W Traynor that might get the treat as well (once I change all the great looking, but quite old Mallory electrolytics).
So many ideas, so little time…

Niki

[bepone]

thx guys , will be some better recs also..

in plan is to raise 22nF to 47nF V1a-V1b coupler , HAD liked to put too big coupling cap for some reason(sculpting low end), which can lead to fuzz on higher gain, but we will see ...

[Reeltarded]

FUN! How did I miss so many posts in this thread?!?

I did have a question and a meaningless suggestion:

What is that cap value and maybe the 10u to 4.7 or even 1u?

A0156299-2B19-4F78-87F0-5F83A9FDF955.jpeg

[bepone]

This cap is 5nF, 0.005uF, i dont know what HAD put there but for the bass shape-ing in overdrive i have put 5.. works well in Soldano (SLO) and Marshall circuits, should work also here - following 430k resistors, i wanted to have Dralorics there but i have only box with those values (430k) , not 470k - if i had 470k i will go with them.

Cathode capacitor originally i have put 10uF, but value is critical how i realised from the tests.. Now is 3.3uF but maybe i will increase it to 4.7uF. I have tried 1uF but the sound was too nervous, shrill! Can be fine tuned

[Reeltarded]

Maybe with the coupling cap at 47u or 50u the bypass isn't too shrill at 1u. Maybe.

The first clip is growling piles of dirt in the lowend like the UP Bandmasters. They are very hmmm,, furry down there.

[bepone]

few short clips from today, i thought will be better recording.. but mob+youtube quality , it is what it is

[bepone]

one more

[Reeltarded]

Rock!

[Mark]

The clips were done with your phone?

The amp certainly has a lot of poke.

[bepone]

a yes clips are with the phone..there is a loss/compression on lower freq.,

i think i will leave it like it is, i like "unchained" character

[WhopperPlate]

one more

You have a good ear . This grinds nicely. It certainly pokes ; rock and roll

[bepone]

Thx, it was from the first powering like this, so i think tight bass is because of OT, vintage Schumacher Bassman's OT are great!

Also here is a impedance miss-match, 4 ohms output from OT to the 8 ohms speaker, but i dont care any more too much for that, i was running blackface bandmaster 4 ohms output to the 8 ohms speaker cab a decade, every day For normal use or home testing, not full power, can pass..

[ChopSauce]

That's pretty impressive!

By the way: any comment on impedance mismatch, "frequency-wise"?

[bepone]

Difference is very small..distortion graph and content will be more to the 3H, but then on low volume there is not so much distortion from output stage, so..classic fender OTs have only one tap 4 - ohm but is possible to connect also 8 without problem. I didnt find any FR degradation, in theory, bass on 8 ohm spk should be weaker then 4 ohms spk, but this is theory, i have here 8 ohms and bass is tight.

Then speaker impedance is not straight line, on every point of the graph we have different transformer ratio..like on pic, spk. varies from 15-250 ohms...
So per example transformer ratio 4k:16 ohms means what?
That we have reflected imp. on primary varies from 3.75k to the 62.5k!

But tubes can handle that, with applying feedback amp is making / playing this uphill part after 300Hz like a straight line,but without feedback amp will play this part like increasing treble! Because output tubes will transfer from voltage source with low internal impedance to the current source with higher internal impedance source, and voltage on the speaker will be Vspk=i*Z, current i will try to be constant, and Z is variable like on the graph.. So output voltage will follow Z from the spk, and like result we will have raising treble.