UP Bassman Main Board Layout

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dorrisant
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Re: UP Bassman Main Board Layout

Post by dorrisant »

Thanks guys!!

I had to change the cathode resistor for the 3rd stage of ch1. I had put a 10k there, changed it to 1k8 and all of the nervousness and exaggerated compression went away. Now I don't know which channel is better. I really love how the ease of balancing the channel volumes turns out to be... Very useful.

Here is a quick and dirty clip.

Using a Friedman Mic No Mo' --> Behringer UMC202HD --> Cakewalk. I think the recording was a bit hot, but you get a good idea from it. I don't want to compress it by exporting to mp3 but when I export to wav it is too big to upload. I'm not sure if SoundCloud defeats the purpose. Whatever. :roll:

I'm playing a '95 Les Paul Classic on the bridge pup, both volumes and both tones at 10. 1st 20 seconds are ch2. Then ch1 until 1:00. Then back to ch2 1st pass with bridge pup then switch to neck at 1:08.

Settings (Presence and Resonance were both at 5, LNFB switch was disengaged):
Clip Settings.jpg


https://soundcloud.com/anthony-dorris-2 ... al_sharing

I must say that this is possibly the quietest amp I've heard in quite a while. Amazing dynamics all around!
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Last edited by dorrisant on Fri Mar 31, 2023 12:20 am, edited 1 time in total.
"Education is what you're left with after you have forgotten what you have learned" - Enzo
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dorrisant
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Re: UP Bassman Main Board Layout

Post by dorrisant »

Here's another clip... Master turned up to 7 1/2, guitar volumes at about 6.

Just some chords for a feel.

https://soundcloud.com/anthony-dorris-2 ... al_sharing
"Education is what you're left with after you have forgotten what you have learned" - Enzo
m.alexander
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Re: UP Bassman Main Board Layout

Post by m.alexander »

dorrisant wrote: Fri Mar 31, 2023 12:16 am Thanks guys!!

I had to change the cathode resistor for the 3rd stage of ch1. I had put a 10k there, changed it to 1k8 and all of the nervousness and exaggerated compression went away. Now I don't know which channel is better. I really love how the ease of balancing the channel volumes turns out to be... Very useful.

Here is a quick and dirty clip.

Using a Friedman Mic No Mo' --> Behringer UMC202HD --> Cakewalk. I think the recording was a bit hot, but you get a good idea from it. I don't want to compress it by exporting to mp3 but when I export to wav it is too big to upload. I'm not sure if SoundCloud defeats the purpose. Whatever. :roll:

I'm playing a '95 Les Paul Classic on the bridge pup, both volumes and both tones at 10. 1st 20 seconds are ch2. Then ch1 until 1:00. Then back to ch2 1st pass with bridge pup then switch to neck at 1:08.

Settings (Presence and Resonance were both at 5, LNFB switch was disengaged):
Clip Settings.jpg

https://soundcloud.com/anthony-dorris-2 ... al_sharing

I must say that this is possibly the quietest amp I've heard in quite a while. Amazing dynamics all around!
i reduce voltage in V1a and V1b more Juice sound ...

145v 135v vs 190v 200v
Marks Amp
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dorrisant
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Re: UP Bassman Main Board Layout

Post by dorrisant »

m.alexander wrote: Fri Mar 31, 2023 11:57 am
i reduce voltage in V1a and V1b more Juice sound ...

145v 135v vs 190v 200v
I will try this when it is burned in for a bit.
"Education is what you're left with after you have forgotten what you have learned" - Enzo
neskor
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Re: UP Bassman Main Board Layout

Post by neskor »

Just to check, on the schematic the bright caps on the volume pots are drawn wrong?
it should be on pins 1-2 not 1-3?
or maybe they are not bright caps :)
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dorrisant
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Re: UP Bassman Main Board Layout

Post by dorrisant »

neskor wrote: Wed Apr 26, 2023 9:46 am Just to check, on the schematic the bright caps on the volume pots are drawn wrong?
it should be on pins 1-2 not 1-3?
or maybe they are not bright caps :)
Which schematic are you referring to?

I didn't install a bright switch but I did install a rock/jazz switch. :D

https://ampgarage.com/forum/viewtopic.p ... 73#p450373
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neskor
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Re: UP Bassman Main Board Layout

Post by neskor »

this one:
Image
check capacitors on each 1M pot
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dorrisant
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Re: UP Bassman Main Board Layout

Post by dorrisant »

Yes, I agree that the bright cap is wrong on that schematic. But that is not what I built. I did end up putting a 47pF cap across the gain pot of channel 1, but none of the pics even show that. The front panel switches are for rock/jazz and channel switching. I am not so sure I have the R/J switch wired correctly either. :roll: I haven't had any desire to play this amp on anything but the rock position. I feel that the PAB position (on-off-on switch, middle position) sounds very thin. Unlike any R/J I've ever built before. When time permits I will revisit. Until then, rock it is. :wink:
"Education is what you're left with after you have forgotten what you have learned" - Enzo
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