Bandmaster Ultra Phonix Amp

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Charlie Wilson
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Re: Bandmaster Ultra Phonix Amp

Post by Charlie Wilson » Thu Jun 22, 2017 12:13 am

Thanks guys. How about this non technical theory. Dumble has knocked the signal down a bit by using those 470k mixing resistors. Maybe the lower PI tail than 4k7 is away of restoring some gain to the output section.
CW

mojotom
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Re: Bandmaster Ultra Phonix Amp

Post by mojotom » Thu Jun 22, 2017 2:50 pm

It will work, I have run Fender based PI with 25k or so feedback and it did open the amp.

Knowing how precisely HAD set the feedback on his amp I doubt he would use such a big fdb R with 47R.
The ones I've seen/heard were used on big stages as a part of multiple amps rigs and they sounded raw, rock, not much gain but very controlled. Make me think of that tweed PI but with some (less) fdb as it was not loose at all either.

We should try it anyway !

beasleybodyshop
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Re: Bandmaster Ultra Phonix Amp

Post by beasleybodyshop » Sat Jul 01, 2017 6:22 am

If it's using Bluesmaster values in the tone stack would it be a stretch to assume he is using BM value Treble/Bass pots? Is it hardwired to Rock mode or Jazz mode?
"It's like what Lenin said... you look for the person who will benefit, and, uh, uh..."

brentm
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Re: Bandmaster Ultra Phonix Amp

Post by brentm » Mon Jul 10, 2017 12:51 am

Mark wrote:
Tue Jun 06, 2017 4:24 am

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? 😜
I noticed that spelling error too! But then I thought it might not be a spelling error... it works both ways.

Mark
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Re: Bandmaster Ultra Phonix Amp

Post by Mark » Mon Jul 10, 2017 8:28 pm

Doh, bad day on the iPhone. 😣
Last edited by Mark on Mon Jul 10, 2017 8:45 pm, edited 1 time in total.
Yours Sincerely

Mark Abbott

Mark
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Re: Bandmaster Ultra Phonix Amp

Post by Mark » Mon Jul 10, 2017 8:42 pm

beasleybodyshop wrote:
Sat Jul 01, 2017 6:22 am
If it's using Bluesmaster values in the tone stack would it be a stretch to assume he is using BM value Treble/Bass pots? Is it hardwired to Rock mode or Jazz mode?
That is the real problem with the photos, this area of the amp allows a lot of variables. I'd be inclined to dismiss the Jazz/Rock switch as I find I lose too much gain. Still it could have one channel Jazz and another Rock.

The mid control is of concern to me as it is 50K and has a lot of effect of the tone of the amp. I like it set low for single coil and high for humbuckers.
Yours Sincerely

Mark Abbott

Charlie Wilson
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Re: Bandmaster Ultra Phonix Amp

Post by Charlie Wilson » Tue Jul 11, 2017 1:56 am

I agree with you to some degree Mark but my take on this is that the amp is kind of a Bluesmaster/Bandmaster hybrid. My guess is that the pots are left Fender stock. I suppose if one really wanted a mid control you could use a mini pot and the second input hole. I am curious if anyone has any ideas on what the purpose and value of the cap across the 100k trem resistor is.
CW

JD0x0
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Re: Bandmaster Ultra Phonix Amp

Post by JD0x0 » Tue Jul 11, 2017 5:57 am

Did HAD ever go with a 12AT7 PI in an UP or are they exclusively BM phase inverter values w/ a 12AX7?
It's true i've lost my marbles and i cant remember where i put them

Aaron
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Re: Bandmaster Ultra Phonix Amp

Post by Aaron » Tue Jul 11, 2017 6:00 am

Charlie Wilson wrote:
Tue Jul 11, 2017 1:56 am
I am curious if anyone has any ideas on what the purpose and value of the cap across the 100k trem resistor is.
CW
Hi Charlie,
Found this on the Aiken website,
A small amount of harmonic distortion is present, as evidenced by the "kink" at the bottom edges of the sine wave. This can be eliminated by filtering the output slightly, either with a post RC filter, or by adding a capacitor across the plate load resistor to act as a first-order lowpass filter to reduce a bit of the distortion. The filter cutoff frequency cannot be made too low at the plate resistor, or the gain will be reduced below the level necessary to sustain oscillation. A good first choice is to select a capacitor that will produce a -3dB point around 3 times the oscillation frequency.

Aaron

Charlie Wilson
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Re: Bandmaster Ultra Phonix Amp

Post by Charlie Wilson » Tue Jul 11, 2017 5:31 pm

Thanks Aaron, I went to the Aiken website read the entire article that your quote came from. Yes I do agree that the cap is there to smooth out the top of the waveform and make the neon bulb less choppy. I guess if you filter it, you have to have enough gain so it doesn't sound too weak thus the smaller 56k(stock 100k) cathode resistor. The cap from the 10m to ground is usually a .02 to get rid of the tremolo ticking but the blue cap looks the same size as the PI output cap. Hmm, that seems a little large. I guess the final assumption would be that the tremolo roach is the original one. I know from my own experience with the newer ones is that they need some smoothing out. Anyway, I have never loved the sound of the blackface tremolo so maybe I'll play around with this a little.
CW

Mark
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Re: Bandmaster Ultra Phonix Amp

Post by Mark » Wed Jul 12, 2017 4:35 am

Let us know how you go Charlie this is all good info.
Yours Sincerely

Mark Abbott

valveandsound
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Re: Bandmaster Ultra Phonix Amp

Post by valveandsound » Mon Jul 17, 2017 11:01 am

I agree the cap across the 100K is to smooth the tremolo "rise".

I think this probably is better addressed in converting the tremolo to bias wiggle, like the princeton. I think I even recall some people anecdotally mentioning that some converted Fender amps had this done.

The 56K tremolo resistor also makes the trem sound more compressed and squash when the intensity is cranked up. The AA763 fender schematic shows some similar value changes here.

So, to clarify, it looks like more or less Bluesmaster clean+PI values, and the other channel looks like...what? Another bluesmaster?

If both are bluesmaster clean, then probably reasonable to assume there is slightly different voicings of each (rock on one, jazz on other, etc)?

Mark
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Joined: Sat Jan 15, 2005 8:10 am
Location: Sydney Australia

Re: Bandmaster Ultra Phonix Amp

Post by Mark » Mon Jul 17, 2017 11:14 am

It could be many different changes. Different mid resistors, Deep control wired in etc. I wouldn't settle on the Jazz and Rock voicing. I don't like how much level is lost in the Jazz mode.
Yours Sincerely

Mark Abbott

Aaron
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Re: Bandmaster Ultra Phonix Amp

Post by Aaron » Mon Jul 17, 2017 1:43 pm

This my guess-timate on the circuit.
I think the bass pots have been replaced, cause you can see the solder tabs compared to the other pots.
Also, I wouldn't be surprised if there's mini trim pots for the Middle soldered directly to the Bass pots. Again, just guessing.

Aaron
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10thTx
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Re: Bandmaster Ultra Phonix Amp

Post by 10thTx » Tue Jul 18, 2017 11:19 am

I tried to redraw Aaron's schematic guess into an editable SCH version. IF anyone sees an error, please make note of that. I'll watch this thread and if no one finds an error, then I will post the editable schematic into the editable D-files. I did have some trouble reading the values on the original Fender schematic.

With respect, 10thtx

CORRECTIONS made and reposted on pg. 4
Last edited by 10thTx on Wed Jul 19, 2017 1:41 am, edited 1 time in total.

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