Ultraphonix adventure
Moderators: pompeiisneaks, Colossal
- Reeltarded
- Posts: 9960
- Joined: Sat Feb 14, 2009 4:38 am
- Location: GA USA
Re: Ultraphonix adventure
Happy New Year!
Yeah, I use 470k mixer. It sounds as expected. Great!
Yeah, I use 470k mixer. It sounds as expected. Great!
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
-
- Posts: 508
- Joined: Tue Jun 06, 2017 12:20 pm
- Location: Montreal, Canada
1 others liked this
Re: Ultraphonix adventure
A quick update on the build, slowly getting there, as I am missing a few resistors and caps.
That feeling when you realize you're missing one diode, the day after placing your order at mouser!
The boards are almost populated, planning on testing a few different coupling caps in the overdrive section. I have a few holes left to drill on the back panel, should be done by tomorrow.
Fred.
That feeling when you realize you're missing one diode, the day after placing your order at mouser!
The boards are almost populated, planning on testing a few different coupling caps in the overdrive section. I have a few holes left to drill on the back panel, should be done by tomorrow.
Fred.
You do not have the required permissions to view the files attached to this post.
Re: Ultraphonix adventure
100k below the tail in PI?
- martin manning
- Posts: 13276
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
2 others liked this
Re: Ultraphonix adventure
Mods - This thread belongs in the D Discussion section.
-
- Posts: 508
- Joined: Tue Jun 06, 2017 12:20 pm
- Location: Montreal, Canada
-
- Posts: 508
- Joined: Tue Jun 06, 2017 12:20 pm
- Location: Montreal, Canada
Re: Ultraphonix adventure
Hey Bepone, have you fixed the motorboating issue on V1?bepone wrote: ↑Thu Dec 14, 2023 12:56 pm After tweaking like crazy all morning, adding RC elements, separating decoupling the tube halves, changng pot, raising the wires in the air.. all what should stop osc - nothing. V1a stopping with LF osc only when i disconnect V1b!
Now im quitting , mazbe i ll rebuild all, but at the end i was changing amplitude in freq. gene and i saw miracle! And tragedy in the same time
Did you try to add a 100pf cap between plate and cathode of V1?
looks like it adds stability on JCM800, maybe that could help ?
Fred.
Re: Ultraphonix adventure
The standard board material can become conductive, have you ruled that out as a possibility?
I rebuilt a Bassman 100 and I replaced the fibre board with a Garolite board as the original board was conductive.
I rebuilt a Bassman 100 and I replaced the fibre board with a Garolite board as the original board was conductive.
Yours Sincerely
Mark Abbott
Mark Abbott
Re: Ultraphonix adventure
my problem is very strange, i tried all what i can think off, remove pot, input, ground input v1a, still is oscillating. but only at no, or low signal, when i increase input to 200mVpp then it acts normally..fred.violleau wrote: ↑Fri Jan 05, 2024 2:34 pmHey Bepone, have you fixed the motorboating issue on V1?bepone wrote: ↑Thu Dec 14, 2023 12:56 pm After tweaking like crazy all morning, adding RC elements, separating decoupling the tube halves, changng pot, raising the wires in the air.. all what should stop osc - nothing. V1a stopping with LF osc only when i disconnect V1b!
Now im quitting , mazbe i ll rebuild all, but at the end i was changing amplitude in freq. gene and i saw miracle! And tragedy in the same time
Did you try to add a 100pf cap between plate and cathode of V1?
looks like it adds stability on JCM800, maybe that could help ?
Fred.
So it us motivating me to work more, some kind of low level creepage??
Conductive board?? Can be..
I will rebuild this part of circuit on another board and connect in the air when i have time and we will see ..
Re: Ultraphonix adventure
Can be.. i have cleaned totally and varnished this board but never checked conductivity between the eyeletts
Re: Ultraphonix adventure
I don’t have an insulation tester so is open an amp and solder an earth wire from the amp and a HT wire across the board and start measuring the eyelets.
https://ampgarage.com/forum/viewtopic.php?f=8&t=36597
https://ampgarage.com/forum/viewtopic.php?f=8&t=36597
Yours Sincerely
Mark Abbott
Mark Abbott
Re: Ultraphonix adventure
Thanks for this thread and fun schematic!
I am curious, what are you doing for the negative feedback circuit?
And is the second volume control is 1meg?
I built a similar version as close as I could get with parts on hand, and it sounds great so far... Gonna keep tweaking and see what I can come up with.
I am curious, what are you doing for the negative feedback circuit?
And is the second volume control is 1meg?
I built a similar version as close as I could get with parts on hand, and it sounds great so far... Gonna keep tweaking and see what I can come up with.
-
- Posts: 508
- Joined: Tue Jun 06, 2017 12:20 pm
- Location: Montreal, Canada
1 others liked this
Re: Ultraphonix adventure
It's alive and kicking!
I have some oscillation going on in the background, could be because of crapy tubes, used whatever was around to test the amp.
OD feels like a Marshall, and EQ responds quite well.
Clean has not much headroom with humbuckers. Past 9o clock and the preamp starts to overdrive. Need to try with single coils.
Put a lar mar type 2 MV and quite happy with it.
I have put different choice of mixer resistors on a relay, so far it does not seem to make much difference. I am playing a celestion rocket, so will report back after playing on my 2x 12.
In terms of NFB where did you end up?
I thinks my Bassman has a 4 ohms output, so will check what I should put in.
Need to touch up a few things here and there, but so far it's a promising start!
Thanks guys for all the info shared!
I have some oscillation going on in the background, could be because of crapy tubes, used whatever was around to test the amp.
OD feels like a Marshall, and EQ responds quite well.
Clean has not much headroom with humbuckers. Past 9o clock and the preamp starts to overdrive. Need to try with single coils.
Put a lar mar type 2 MV and quite happy with it.
I have put different choice of mixer resistors on a relay, so far it does not seem to make much difference. I am playing a celestion rocket, so will report back after playing on my 2x 12.
In terms of NFB where did you end up?
I thinks my Bassman has a 4 ohms output, so will check what I should put in.
Need to touch up a few things here and there, but so far it's a promising start!
Thanks guys for all the info shared!
You do not have the required permissions to view the files attached to this post.
Re: Ultraphonix adventure
interesting, very nice, one more is alive!
- Reeltarded
- Posts: 9960
- Joined: Sat Feb 14, 2009 4:38 am
- Location: GA USA
Re: Ultraphonix adventure
Yay, Fred!!
I think 100k on the 4R.. nope, I think I moved it to the 8.
I think 100k on the 4R.. nope, I think I moved it to the 8.
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
-
- Posts: 508
- Joined: Tue Jun 06, 2017 12:20 pm
- Location: Montreal, Canada
2 others liked this
Re: Ultraphonix adventure
I tried the preamp out into another amp cause the clean was bugging me. It is outstanding, very close to the john Mayer amp feel and no issue with the overdrive, channel, so something is happening down the line. Will check voltages again, but nothing seemed of.
Fred.
Fred.