UltraSonic Studios Amps
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Oct 29, 2022 at 2:26 PM Post #6,662 of 7,569
There are ports for a meter next to each output tube. Set the bias and voltage (via the center meter), turn off the amp, wait 5 minutes, put in tubes, then turn on. That’s the way @SonicTrance wants it done. Once the tubes are warm check the bias meters and correct as needed.
Very neat, I wondered about that centre meter, so can you set any value?
 
Oct 29, 2022 at 2:34 PM Post #6,663 of 7,569
Yes, they are the exact same size :)

It hasn't sink in yet that I will have 3 tube amps built by you but I am loving Oblivion and Odyssey very much now. All 3 amps will be very different in design and sound. To have Odyssey with Sowter and Telemachus with Monolith, it wasn't planned but it turn out more than I anticipate what my final setup will be. The enjoyment that I get out of my amps is incredible. I will not have it any other way.

I haven't really listen with Susvara for a week but now that I have it strapped on my head with Odyssey powering it, the euphony sweeps me off my feet. Such a wonderful sweet tone. It's one of life's simple pleasure for me.
 
Oct 29, 2022 at 2:40 PM Post #6,665 of 7,569
Very neat, I wondered about that centre meter, so can you set any value?
There are limits. I can set the anode voltage anywhere between 250v to 400v. I have to be careful about biasing the tube at lower voltages. The lower I set the anode voltage the more current the regulator has to eat so it limits how much current I can set with the bias. I've been advised that if I run tubes at 250v I should not exceed 30ma bias. That scales up to 50-60 ma if I run it at 400v.
 
Oct 29, 2022 at 5:36 PM Post #6,666 of 7,569
Those transformers look excellent! What happened to the mains transformer? Will you be using Monolith again for the mains?
The mains transformer hummed under load. I've sent it back for them to have a look at. I'll most likely not use their mains again unless I really need a custom one. That's mostly because of cost. I see little to no benefit by using those mega expensive mains. I do love their OT's though!
 
Oct 29, 2022 at 5:56 PM Post #6,667 of 7,569
The mains transformer hummed under load. I've sent it back for them to have a look at. I'll most likely not use their mains again unless I really need a custom one. That's mostly because of cost. I see little to no benefit by using those mega expensive mains. I do love their OT's though!
So you love the output transformers… That implies you liked what you heard while testing…

Their reputation, or at least the chatter I have seen about them, has been all about the single ended transformers. I wasn’t sure they would make a big difference for push pull. Figured that if this was going to I be my last push pull amp why not go for it? Tomas, when you do the 300b amps what core material will you use?

I am using external supplies for the heaters but I wonder how difficult it would be to integrate variable SMPS inside a chassis. Might make more sense with a two chassis amp. When I thought about the variable heater, anode, and biasing I wondered why other companies aren’t offering those things. The obvious hit me, I’m bound to screw something up at some point and blow stuff up. A regular manufacturer would be nuts to put this kind of control in users’ hands Lol. Way too many ways to screw up. But if you truly want to plumb the depths of tube rolling insanity you gotta be willing to risk a few screw ups. That’s how I’m justifying it at least.
 
Oct 29, 2022 at 7:17 PM Post #6,670 of 7,569
Hammond mains in Odyssey does its job very well. Quiet and reliable. Trouble free in the one year it’s been performing.

Hammond will again feature in my Telemachus.
I’ve got a toroid in mine. As long as it can deliver the power and stay quiet I think just about any properly specced power transformer will be fine. My heater supplies are SMPS.
 
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Oct 30, 2022 at 5:00 AM Post #6,672 of 7,569
There are limits. I can set the anode voltage anywhere between 250v to 400v. I have to be careful about biasing the tube at lower voltages. The lower I set the anode voltage the more current the regulator has to eat so it limits how much current I can set with the bias. I've been advised that if I run tubes at 250v I should not exceed 30ma bias. That scales up to 50-60 ma if I run it at 400v.

I see. That's a very neat trick, I might try it on my LD... if I can figure out how Sonic did it!!

... I wonder how difficult it would be to integrate variable SMPS inside a chassis. Might make more sense with a two chassis amp. When I thought about the variable heater, anode, and biasing I wondered why other companies aren’t offering those things. The obvious hit me, I’m bound to screw something up at some point and blow stuff up. A regular manufacturer would be nuts to put this kind of control in users’ hands Lol. Way too many ways to screw up. But if you truly want to plumb the depths of tube rolling insanity you gotta be willing to risk a few screw ups. That’s how I’m justifying it at least.

Yes, a lot of ways to screw things up LOL.

Re: SMPS here is a pick of my APPJ showing the SMPS behind the metal screen, amp and PS all in the same chassis, and a small one at that. It is completely quiet. Just to show you it can be done, don't know if Sonic would advise though.

1667120216532.png
1667120323072.png
 
Oct 30, 2022 at 5:09 AM Post #6,673 of 7,569
A properly used Hammond organ can be awesome through an amp!
Yes, and I use Amperex Bugle Boy type tubes which are specially screened for Hammond organs, so they must be good!

1667120954384.png
 
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