I think the next steps are for me to build and verify the CSX2 version of the board (different input scheme, and different PSU / bias scheme).
If anyone would be interested in prototyping a board, I would be willing to send you an OS and one or both of the FE boards, for free. Most of the decisions that need to be made around more mechanical and physical layout, more than electrical.
The output stage board I designed can implement the CSX2 schematic as called out, by setting some jumpers and changing a few components . I just want to make sure it actually works, as to date I have only built the VFET2 OS.
I finished my build.
I am very impressed with the sound of this amp. One of the best I've heard since quite some time. Hard to describe it.
- Very quiet background, as if it has less 'noise' than other amps, let's me listen "deeper" into the music.
- Very detailed, without being exhausting/nerving, and at the same time fluid, relaxed.
- Music, esp. voices have presence,shimmer,brilliance (something which I heard also from a J2 before.)
In short: The perfect amp for me. Now I am considering to build a 2 or 3 output version.
I am very impressed with the sound of this amp. One of the best I've heard since quite some time. Hard to describe it.
- Very quiet background, as if it has less 'noise' than other amps, let's me listen "deeper" into the music.
- Very detailed, without being exhausting/nerving, and at the same time fluid, relaxed.
- Music, esp. voices have presence,shimmer,brilliance (something which I heard also from a J2 before.)
In short: The perfect amp for me. Now I am considering to build a 2 or 3 output version.
Voltages are as follows
G-t6 +30.1; g-t4- .35; t6-t7 +1.35; t6-t11 10.54; g-t18 .93; g-t14 +14.66; g-t19+8.06; g-t17 -9.27;g-t8 -30.06;g-t2 +.56; t8-t9 1.37; t8-t13 -10.15;g-t15 -14.64;g-t20-11.43;g-t16 +6.63
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It is a FirstWatt supply inspired, selfmade PCB design. It was a small series of 3 boards for my own use. Functionalitywise it's the same as the Universal PSU board in the diyaudio store. Main addition is the Temperature-circuit-breaker.
However I believe this circuit breaker won't save the VFETs. If the amp is getting way too hot, the VFETs might be gone already.
I bought nylon spacers from AliExpress, will check how they fit soon.
They are 5mm length, 7mm outside diameter, 3mm inside diameter for V-FET pins and 4mm inside diameter for bolts.
Now that I think about it maybe I should have bought plastic spacers.
Nylon is not the best material for hot environment.
Thanks all, I just did that with my Nylon spacers which were perfect fit. So I just used the one which came in the kit for measuring the length and cut it for the exact hole requirement. Works and now the mosfets are being soldered for the second channel and the first channel works perfectly.
Thanks again all, will report back on how it sounds later in the night
Hi,
I do have a question about the matching of the VFETs, as I want to build a 2 or 3 output version.
I have matched mine using Locky_z intelligent curver tracer:
Intelligent Curve Tracer 3.0 release
I think the curve-tracer sends only short Current/Voltage pulses into the VFET,
and therefore there is no or only very-low temperature increase of the transistor.
Nelson mentioned he used temperature controlled heatsinks for matching.
Is that curve-tracer matching good enough, or do I have to match them on a temperature-controlled heatsink, using lab power-supplies to control Vgs ?
I do have a question about the matching of the VFETs, as I want to build a 2 or 3 output version.
I have matched mine using Locky_z intelligent curver tracer:
Intelligent Curve Tracer 3.0 release
I think the curve-tracer sends only short Current/Voltage pulses into the VFET,
and therefore there is no or only very-low temperature increase of the transistor.
Nelson mentioned he used temperature controlled heatsinks for matching.
Is that curve-tracer matching good enough, or do I have to match them on a temperature-controlled heatsink, using lab power-supplies to control Vgs ?
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Thanks all, I just did that with my Nylon spacers which were perfect fit. So I just used the one which came in the kit for measuring the length and cut it for the exact hole requirement. Works and now the mosfets are being soldered for the second channel and the first channel works perfectly.
Thanks again all, will report back on how it sounds later in the night
So I did the setup for both the channels as per the guide and perfect 100mV and +/-2mv to 10mv was the offset after installing the VFETs. Happy and then used some crocodile clips for the input/output wiring and powered it up with some DIY speakers in the morning and music played smoothly. Dead silent with my mobile phone using TIDAL app. Played for more than 2 hrs at a stretch at low volume.
Later in the day I used proper shielded wiring for the input wiring (Canare interconnects) and thin wires to the speaker protection module. Checked all the wiring and the DC voltage and everything seems going well, so powered it up and suddenly one of the LED went off on one of the channel. I immediately switched off the power and checked for any loose wiring but nothing seems to be the issues with the wiring. But now the LED is not glowing and the relays are not clicking as well as LED on the speaker protection module also not switching on. Not sure what the issue is, what could be the issue with one of the LED not glowing on one of the VFET pcb board but the other one works. Any pointers for debugging will be helpful.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Thanks
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