It normally warms up during some minutes and levels off. I didn't notice it going down. VAS current also depends on Vbe of a number of transistors (Q4, 5, 6, 7, 8, 9, 11, 12) and values of R32, 33, 41, 44. But those are normally rather stable - not getting hot or something.
As soon as it's slightly above 35V - that's ok. But don't go below that level - the tube will not like it, distortion will start growing.
Both channels are somewhat operational now. Running standalone they operate well with clipping starting around 1.5VRMS. I haven't got a proper supply assembled for it and only had 6800uF on each rail. Operation with an output board wasn't so good into a 4 ohm test resistor. No sign of instability but negative swing was distorting heavily in both rails. Time to assemble a proper supply and chassis and test some more. I still would like to get the inputs to operate with identical components at some point. Thanks for all your help.
Hi Jeff, good progress.
Are you using the "original" lateral fet output sections?
Do you mean 1.5VRMS at the input?
Did you bias the outputs properly?
Are you using the "original" lateral fet output sections?
Do you mean 1.5VRMS at the input?
Did you bias the outputs properly?
I'm using the Tubesomo output boards with Renesas laterals. Clipping starts slightly above 1.5V on the input. Bias seemed to really be tough to set. Temperature seemed to make much more adjustment that the trim pot did. I was able to eventually get them to settle around 16mV across the RE resistors. I've been pumping myself full of headcold medication for the last few days and it's taking it's toll. I'm vibrating so bad I blew up one of the output boards trying to connect my volt meter.😡I can't think properly like this either. My troubleshooting skills really suffer.
Take a break , Jeff.
Don't touch no electrics when either sick or "grogged.
OS
I have been taking it easy and looking over some projects I have on the go. I've noticed a couple errors in the latest protection board. Don't bother populating yours when they arrive. I'll send updates.
Hi Guys,
I have a couple of the guys who requested boards for this amp changed their minds so I have two complete sets of the PCBs available for those who may be interested. PM me if you are.
I will wait a little while before offering them in the swap meet.
Blessings, Terry
I have a couple of the guys who requested boards for this amp changed their minds so I have two complete sets of the PCBs available for those who may be interested. PM me if you are.
I will wait a little while before offering them in the swap meet.
Blessings, Terry
Sure Jeff,
Just PM me. I plan to try the FET version as well. That one should work at a wider range of rail voltages.
Blessings, Terry
Just PM me. I plan to try the FET version as well. That one should work at a wider range of rail voltages.
Blessings, Terry
Futurlec claims to have them in stock. I've never ordered anything from them so I can't make a recommendation one way or the other.
Futurlec, The Electronic Components and Semiconductor Superstore
OK Jeff bought one set so I just have the one set left. PM me if interested.
Jeff, I ordered some 2SK117s from Furturlec. Looks like they have them.
Looking forward to comparing the Tube version with the FET version.
Jeff, I ordered some 2SK117s from Furturlec. Looks like they have them.
Looking forward to comparing the Tube version with the FET version.
Hello All!
I would be also very interested in comparison of the Tube one and FET one - got the Tube one and like it a lot, but never had a chance to test the FET one 😛
By the way - look at what I have started just few days ago:
>Almost all-FET 8-transistors front-end, especially good for TubSuMo Lateral-FET OPS (by design)<
I have put it to that CFA thread as it is actually a CFA front-end, however, I will probably copy that post here as well as it's rather related to this thread - for those who will miss the link 🙂
It's just the beginning - PCB and prototype will follow...
Cheers,
Valeery
I would be also very interested in comparison of the Tube one and FET one - got the Tube one and like it a lot, but never had a chance to test the FET one 😛
By the way - look at what I have started just few days ago:
>Almost all-FET 8-transistors front-end, especially good for TubSuMo Lateral-FET OPS (by design)<
I have put it to that CFA thread as it is actually a CFA front-end, however, I will probably copy that post here as well as it's rather related to this thread - for those who will miss the link 🙂
It's just the beginning - PCB and prototype will follow...
Cheers,
Valeery
Attachments
My hands have almost stopped shaking so hopefully I can see what all I've damaged on mine soon and see what it sounds like.
I finally got everything together to try the tubsumo ips together with its intended ops. Thanks to Terry for the boards vzaichenko for the design and everyone for the help. Started right up and runs great...Sometimes I forget I'm not an auto mechanic anymore. Offset settles at less then 1 mV. Tomorrow I'll install the amps into the main system.
Will there be any problem upping the supply voltage from +-72vdc to +-85vdc?
I'll report back with listening results.
Thanks, Evan
Will there be any problem upping the supply voltage from +-72vdc to +-85vdc?
I'll report back with listening results.
Thanks, Evan