Things left to iron out en route to a complete amp:
That will take a while...
- Install speaker DC protection board
- Add IEC inlet plus switch and fuse
- Add safety earth connection from PSU to a point on the chassis frame or heat sink
- Add a switch and chassis connector for the separate 12vdc SMPS that powers the 12au7 heater (I was hoping to use the aux supply on the big smps, but that introduced more hum on the output before)
- Cut and install lexan panels
That will take a while...
The amp control boards actually came about for starting and protecting this amplifier. It would be a good choice here, and save a bit of chassis work. No need for extra switching and fusing, just a small push button and LED on the front. Also after the amplifier is started there needs to be a delay to let the tube stabilize before DC offset settles out enough not to trigger a normal DC detection circuit.
Amp Control System 6 V2.3 Boards Bundle (5 PCBs, Simpelstark family) – Virtual Zero Audio Store
Amp Control System 6 V2.3 Boards Bundle (5 PCBs, Simpelstark family) – Virtual Zero Audio Store
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That control system is a great design. But since I’m building monoblocks and want to keep the existing footprint (see my earlier post Ultra-high performance, yet rather simple - hybrid and more!), the control boards may take up too much space. The only cutting I’m expecting to do for the chassis is in lexan, so I’m hopeful my dumbed-down control will agree with that. 
My SSR protection boards work fine. Perfectly if the tube is already warm.
It also works from cold power on of both the amp and tube smps at the same time.
The DC sensing works just fine in my application. The SSR light goes on briefly after the initial delay, then shuts off quickly as the DC offset rises, then goes back on after DC goes back down. My DMM didn’t read any more than 350mV the whole time.
DC went to 1.5V for an instant after power off.
I think I’ll still incorporate a switch for the tube smps just to be safe.
It also works from cold power on of both the amp and tube smps at the same time.
The DC sensing works just fine in my application. The SSR light goes on briefly after the initial delay, then shuts off quickly as the DC offset rises, then goes back on after DC goes back down. My DMM didn’t read any more than 350mV the whole time.
DC went to 1.5V for an instant after power off.
I think I’ll still incorporate a switch for the tube smps just to be safe.
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For anyone interested; some populated PCBs for sale
FS : VZaudio NS OPS Amplifier with two different IPS
BR
Eric
FS : VZaudio NS OPS Amplifier with two different IPS
BR
Eric
Two TubSuMo monoblocks are operational!
There is some background noise, but not noticeable away from nearfield.
They’re playing through my test speakers well now. DC offset servos are working perfectly.
I’ll try them out in my main rig tomorrow. Then I’ll affix some lexan panels and figure out the hardest part: final chassis details (mounting connectors, IEC socket, switches, etc.).
This open frame makerbeam build has been fun.
There is some background noise, but not noticeable away from nearfield.
They’re playing through my test speakers well now. DC offset servos are working perfectly.
I’ll try them out in my main rig tomorrow. Then I’ll affix some lexan panels and figure out the hardest part: final chassis details (mounting connectors, IEC socket, switches, etc.).
This open frame makerbeam build has been fun.
Attachments
I’ve been running my TubSuMo mono amps every day, with nightly louder sessions. They have exceptional sound quality and finesse. It’s a tossup in level of enjoyment between these and my updated Hafler DH-220C amp. These are certainly prettier.
Thanks again to Valery and jwilhelm for the design and help, and to Evan for building the boards and sinks well (and selling them to me)!
‘The lottery’ is commanding a lot of attention on the forum—and rightfully so—but any potential builders should look into vzaudio projects for top-notch amplifier options. Great design, support, and results!
Thanks again to Valery and jwilhelm for the design and help, and to Evan for building the boards and sinks well (and selling them to me)!
‘The lottery’ is commanding a lot of attention on the forum—and rightfully so—but any potential builders should look into vzaudio projects for top-notch amplifier options. Great design, support, and results!
