Ultraphonix adventure

[Reeltarded]

-bumps jukebox-

What is taking so long?

[bepone]

missing some quality recorder!

[bepone]

amp assembled in 2 days! with all the cleaning etc..

tubes selected for High gain (important):
V1: EX 12AX7 - this is standard for higher gain, normal sound, high gain, nice bass, low noise
V2: JJ ECC83 - for cathode follower
V3: ECC83 Telefunken (yes, for clean)
V4: low gain ECC83 - some GT groove tube/ used tube, on the mid of the life/ measured to have low gain

53 (Medium).jpg

amp at the moment / need to change the heater wiring with time /

191 (Large).jpg

for output and for the test taken used 6L6's GT, measured somewhere on medium of current and gm..but still ok.

Some notes on the layout.. Positive feedback where was possible, on V1 and V3. NFB isolated to go directly to spk terminal, but maybe with time i will put closer to grid wires. Coax for gain channel. Added one more node on capacitor bank, to separate gain stages V1, V2. Added separated ground lines for V1 and V2 from cap. bank.

190 (Medium).jpg

[Reeltarded]

Looks great! I took a break from working on a pedal to bag parts for mine, but still unsure about a few things.

Make a video! Does it sing?

[bepone]

yes

about the sound i have played totally 5h on the amp.. there is absolutely all positive about,
1. great clean on "clean" channel (altough how i'm playing i found that there can be more chime, i think this 470k before PI is too high and it is stealing some highs, on next tweaking time i will reduce that resistor to 330k, or 220k and check again)

2. great crunch on "gain" channel , gain and volume to half - apsolutely great, nothing to add here

3. great overdrive on "gain" channel , this is rock machine! bass is tight , creamy and powerfull, but how the time passing looks like is 20% more bass than is needed so i will reduce some coupling cap (on the schematics there is 47nF there on V1b, middles are not so pronounced and sharp, treble is very nice and rounded! gain on 80% makes sound little bit over-copressed (i have 1k8 in cathode in V2a, maybe i need to go to other side -> 820R-1k like on Marshall-or 5F6A bassman)

when i'm listening to other UP youtube videos , my version has litlle bit less gain, so i will re-think about anode resistors used

[Reeltarded]

Love this interpretation of same amp.

[Reeltarded]

yes

when i'm listening to other UP youtube videos , my version has litlle bit less gain, so i will re-think about anode resistors used

What are they now? I wish could get inside the Marshall version, which is hardly different from the white Showman, except the cleans are UNREAL in the Marshall. The dirt on both is honking like a horn and blows into feedback just because it feels like it.

[bepone]

here is the schematic,
missing first gain 1MA
V1 gain stage, 180k/2k7, second half 130k/1k8
V2 CF: 150k/1k8, cathode follower 82k cathode (intended compression, not like "normal" 100k/100k)

sema.jpg

[bepone]

this is working great, i dont know if those are Dumble values, but is working great...

Now started to tweak bass - i have changed V1a cathode cap to 0.68uF, increased coupling cap V1a 22nF-47nF, and reduced V1b cathode cap 10uF->3u3. And for result i get less bass and screaming middle! So i came back to values in the schematic, this need to be tweaked very gently...

[Reeltarded]

Instead of cutting bass why not try a larger mid resistor? Make it a little more forward and maybe sing a little more..

25k?

At least 15k heh

[bepone]

can be can be, also return from Soldano style 47k slope to Marshall 33k what is seen in real UP pics

[Mainetone]

Thanks for posting the your schematic!

[Mark]

So is this really an Ultraphonix amp or squeezing a Marshall into a Bassman amp?

I’m fairly ignorant when it comes to UP amps.

Thanks for sharing the info with us.

[Reeltarded]

It is a representation of the somewhat common Dumble mod on Bassman UP amps. The normal side channel is high gain and other channel is UP values with added mid control.

[bepone]

So is this really an Ultraphonix amp or squeezing a Marshall into a Bassman amp?

I’m fairly ignorant when it comes to UP amps.

Thanks for sharing the info with us.

some better picture from internals will help, but the UP thing is only in variation to several resistors (anode and cathode) in V, V2 from Marshall JCM800 style, and there is capacitor across the anode resistor to tame some highs.. plus lead dress , which for sure others doesn't care too much or make like Dumble and this can make so much difference in tone..