Bandmaster Ultra Phonix Amp

[Mark]

There's more than one voicing of these

What other voicing are you aware of. Care to share your observations?

The Dumble bluesmaster I built has the best clean sound of all the dumbles I've made. It's lovely and full and LOUD. If you like fender cleans then the BM is a great place to start. reminded me of a twin but nicer sounding when pushed.

This is in the same vein as the other quote, I too built a Bluesman Master and found the tweed P.I. stage was a big part of the amps sound. I think a different voicing would probably require a different P.I. stage.

With regard to the mega boost. I didn't particularly like the volume change once I kicked the mega boost in and as a result I didn't use it much. Perhaps that is the case in this amp.

[Aaron]

All these modded circuit names are so confusing. I thought the Ultra Phonix is a clean only?

Ultra Phonix - 2 x Bluesmaster Channels & Bluesmaster PI
Hotel Hog - Pre-Classic Channel, Bluesmaster Channel w/Mega Boost & Bluesmaster PI
LaTostada - JCM800
Manzamp - Bassman w/Skyliner Voicing & EL34
Slidewinder - Bassman Voiced?

I know this is a broad generalisation, are there other models?

[splgeo]

The UP mods differ between what the amp started out as.
The Bandmaster/Showman/Bassman/Marshall all may be labeled UP but are all different. They all retain some of the original charter of the base amp

[Mark]

I wonder what is going on with the midrange control resistors. Given the mid control is 50K there is a lot of range to cover.

I wonder if the output transformer is the stock one or a Bassman O/P transformer?

I noticed the label mentions amp pirates as a discussing lot as opposed to a disgusting lot. Maybe he's softer in his old age?

[Smokebreak]

the tone stack is the same as the blues master150k/120k plates 150k plate 2.2k cathode.... the 120kplate shared cathode 900ohm, resistor. normal channel looks like 330pf .022/.022 47k slopev1b coupling cap looks like .05uf......... vib channel 250pf .022/.022 47k slope... v2b coupling cap looks like .1uf. and a few caps added to the optocoupler.

power tube grid resistors changed too 5.1k

this is what I see

V1a cathode looks like red purple red, no?

[splgeo]

It's possible. If you go by the 1:66.66666 rule.... that would make the plates 180k cathode 2.7k

[FuzzFaceBuilder]

Looking at the photos in this thread, I can't tell if it's 6PS or 716 polypropylene. Any thoughts?

[splgeo]

MOST LIKLEY 715S

[Mark]

I would have said 6PS caps over the 715 and 716 caps.

I think I have seen the 715 and 716 caps in the Phase Inverter. They sound good there.

[Charlie Wilson]

Hello, been staring at the photo. Shared cathode looks like 1k to me, so I'm thinking 130k NTE for second plates. Roderstein mk3 180k first plates. Phase invertor plates 91k and 100k. Summing resistors 475k like Marshall 470k. Getting ready to do something like this to my Pro Reverb.
CW

[Charlie Wilson]

Is anybody else seeing a black band on the phase invertor tail resistor? I think it may be yellow, purple, and black. Making it 47 ohm.
CW

[dcribbs1412]

Is anybody else seeing a black band on the phase invertor tail resistor? I think it may be yellow, purple, and black. Making it 47 ohm.
CW

Possibly
so 10k and 47 ohm as opposed to 22k and 100ohm bandmaster?

D

[Charlie Wilson]

Yep, like a Tweed Bassman or Marshall phase invertor. Usually that tail resistor would be a 4k7 but that third band does not look red to me.
CW

[mojotom]

Very happy to have a look, I like those UP a lot.

47R would have make sense with 820R fdb resistor (with 22k tail but 10k works too). Quite a bit less NFB with 47R vs 100R so it does boost the output stage nicely.

100k feedback resistor here so 4k7 would be my guess i.e. Plexi type PI. No .1 cap so presence off.


Btw thanks Charlie for all the sharing here !

[ToneMerc]

Is anybody else seeing a black band on the phase invertor tail resistor? I think it may be yellow, purple, and black. Making it 47 ohm.
CW

CW, I think it's brown, 470R.

TM