Hello,
I've finished reading this whole thread and was hoping that some of you might offer some advice on which version of the VFet amp to build.
After quite some time, I've managed to get a hold of 4 pairs of 2SK82/2SJ28, and I've made enough progress with the DIY chassis that I'm now trying to decide if I should build the VFet part 2 version, or a bridged DIY Vfet version (the 1 pair VFet version).
The advantage of the bridged version would be the balanced input (my preamp is based on the UGS, and the DAC on the NTD1, so I would keep a balanced connection throughout the system), but I've read a few hundred pages back that it might not be such a good idea. I have to admit that I didn't fully understand the explanation that was given.
My speakers have a nominal impedance of 8 ohms, whit a dip down to 6.2 ohms, so a bridged version would be feasible from what I understand.
I figure that very few have been lucky enough to build both the part 2 version and a bridged DIY version to compare them from a sonic perspective, but which of the 2 would you chose, from a practical and technical view point?
Thank you!
I've finished reading this whole thread and was hoping that some of you might offer some advice on which version of the VFet amp to build.
After quite some time, I've managed to get a hold of 4 pairs of 2SK82/2SJ28, and I've made enough progress with the DIY chassis that I'm now trying to decide if I should build the VFet part 2 version, or a bridged DIY Vfet version (the 1 pair VFet version).
The advantage of the bridged version would be the balanced input (my preamp is based on the UGS, and the DAC on the NTD1, so I would keep a balanced connection throughout the system), but I've read a few hundred pages back that it might not be such a good idea. I have to admit that I didn't fully understand the explanation that was given.
My speakers have a nominal impedance of 8 ohms, whit a dip down to 6.2 ohms, so a bridged version would be feasible from what I understand.
I figure that very few have been lucky enough to build both the part 2 version and a bridged DIY version to compare them from a sonic perspective, but which of the 2 would you chose, from a practical and technical view point?
Thank you!
Sony V pt 2 is very special. I would build one and use it unbalanced. I prefer the sound without feedback, but you’ll want to try both. The diy version needs feedback, so no feedback option.
The pt 2 has lots of power with 85db speakers. Doubtful you’d need more unless you like pain.
The pt 2 has lots of power with 85db speakers. Doubtful you’d need more unless you like pain.
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The speakers are 2-way floor standing speakers (18 cm woofer) with SPL (1 m / 2.8V) of 85 dB and the room is about 7 m x 5.5 m.
That's what I gathered from reading what others wrote about the part 2. I'm just wondering if I'm negating any qualities from the balanced system upstream by going unbalanced to the amp.
for my taste - speakers are too small for room and efficiency too low ...... for decent SPL (not cannons , just decent) - what - you need 1m Xmax?
OK , let's say that's matter of taste , but these speakers are just not in the same Story as Sony amps are - where power is second to sound quality
with more efficient (while easy to drive 8-ish) speakers , I would say - go with bridged
in this case , I see you need power .... and I believe you better search for some amp where power is already there
OK , let's say that's matter of taste , but these speakers are just not in the same Story as Sony amps are - where power is second to sound quality
with more efficient (while easy to drive 8-ish) speakers , I would say - go with bridged
in this case , I see you need power .... and I believe you better search for some amp where power is already there
The room isn’t small, but it’s not a dedicated sound room, therefore I’m relatively limited in the speaker size I can use. That being said, my seating position is about 1.5-2 m from the speakers so I don’t need them to fill the whole space. Although I understand what you mean about the required Xmax vs the total air volume in the room vs the bass.
The speakers are based on Troels’ CNO-mkii. I would think that they are pretty decent from a sound quality point of view. Would be nice to change them to the 2.5 way or 3 way CNO, but that’s a whole new project and would decrease the impedance to 4 ohms which would not be great for the bridged version.
I’m currently using a DIY UP amplifier, but wanted to build and then hear a VFet amp.
The speakers are based on Troels’ CNO-mkii. I would think that they are pretty decent from a sound quality point of view. Would be nice to change them to the 2.5 way or 3 way CNO, but that’s a whole new project and would decrease the impedance to 4 ohms which would not be great for the bridged version.
I’m currently using a DIY UP amplifier, but wanted to build and then hear a VFet amp.
JoeyDD,
Read post #3715 by Botte.
I built the 2 pair version and am using it to drive the mid/highs of my Troels OBL15. F5TV3 drive the bass units.
To fully exploit the potential of the Sony Vfet amps you need a preamp that has the spectral harmonics to match, to give you the kind of sound you are looking for. When done correctly large orchestral works sound simply stunning. It has taken me a few months to get it right but I am now very pleased with the sound.
I agree with ZM about the two bridged units option only because you need the extra power. Can you biamp your speakers?
nash
Read post #3715 by Botte.
I built the 2 pair version and am using it to drive the mid/highs of my Troels OBL15. F5TV3 drive the bass units.
To fully exploit the potential of the Sony Vfet amps you need a preamp that has the spectral harmonics to match, to give you the kind of sound you are looking for. When done correctly large orchestral works sound simply stunning. It has taken me a few months to get it right but I am now very pleased with the sound.
I agree with ZM about the two bridged units option only because you need the extra power. Can you biamp your speakers?
nash
Hi Nash,
I recall reading a posts where someone mentioned having underwhelming results with a certain preamp and much better with another. Do you think the UGS will not match well with one of the VFet amps?
Unfortunately I built the mkii version of the CNO a few years ago, which has a series crossover.
It looks like the bridged version is the one I should try with my current speaker. Until I build new speakers, I’ll have to keep in mind that it might be underpowered.
I recall reading a posts where someone mentioned having underwhelming results with a certain preamp and much better with another. Do you think the UGS will not match well with one of the VFet amps?
Unfortunately I built the mkii version of the CNO a few years ago, which has a series crossover.
It looks like the bridged version is the one I should try with my current speaker. Until I build new speakers, I’ll have to keep in mind that it might be underpowered.
Mind expanding on this, if you have any additional info?
If I'm remembering correctly, the VFET amps are 3rd harmonic dominant, so are you saying that ideally you would pair it with a 3rd harmonic dominant preamp?
This VFET version 2 amp sounds great with (or without) the Pass Korg B1 NuTube DIY preamp project (second harmonic generator). I was listening to v.2 last week again on my midrange ribbon and was impressed once again. v.2 VFET is a fantastic and perhaps best of all STAX headphone amp driver with a custom voltage transformer liaison.
My version of VFET v.2 uses single pairs per channel. Not quite as spooky as the First Watt single ended SIT, but not too far and in the family for sure. It sounds cleaner, maybe a little less sweet than the older medieval Sony VFET amps, but more focussed.
I am curious to hear the SIT 3, but I don't know if that will ever happen unless it shows up at an audio exposition.
My version of VFET v.2 uses single pairs per channel. Not quite as spooky as the First Watt single ended SIT, but not too far and in the family for sure. It sounds cleaner, maybe a little less sweet than the older medieval Sony VFET amps, but more focussed.
I am curious to hear the SIT 3, but I don't know if that will ever happen unless it shows up at an audio exposition.
When I first set up the Vfet amps I used them with my BA3preamp and found the sound a bit edgy. So I figured I needed some H2 and adjusted the Vfet amps to give equal H2 and H3 from the previously dominant H3 setting. This sounded good and I listened for a couple of months this way.
Then I thought what if I increased the H2 at the preamp and again reduced it at the power amp. So I tried that. I experimented with different settings for the preamp and Vfet amps.
Long story short- the 2 pair Vfet amps in my experience, sound best when each channel is set close to the distortion level published by Mr. Pass in his article. This is with feedback.You can then adjust H2(negative and dominant in my case) of your preamp to give the final sound that you like for your music and setup.
nash
Hi everyone!
Papa has noties: with 24VDC:
22V = 2.5V * (R15+4750 ohms)/4750 ohms 22V *4750 ohms / 2.5V = R15 +4750 ohms 41800 ohms = R15 + 4750 ohms
R15 = 37050 ohms.
You would pick the closest 1% resistor, which would be 36K or 36.5K for R15 and R16.
So with 28 vdc we have R15 or R16 is 44650 ohms. But in the schematic resistors 15 and 16 is 41.2 kohm
Which value is right for 28vdc voltage? 44.6 kohm or 41.2 kohm?
Thanks
Papa has noties: with 24VDC:
22V = 2.5V * (R15+4750 ohms)/4750 ohms 22V *4750 ohms / 2.5V = R15 +4750 ohms 41800 ohms = R15 + 4750 ohms
R15 = 37050 ohms.
You would pick the closest 1% resistor, which would be 36K or 36.5K for R15 and R16.
So with 28 vdc we have R15 or R16 is 44650 ohms. But in the schematic resistors 15 and 16 is 41.2 kohm
Which value is right for 28vdc voltage? 44.6 kohm or 41.2 kohm?
Thanks
Thanks! That makes sense. Out of curiosity, did you measure the distortion spectrum at the end of the full chain (preamp + amp) once you found the individual settings on each that you preferred?
That would be great. I have only seen it in static display, and it probably deserves a live demo showing amongst the gboyz brotherhood.
I could go to for my first BA as a DIY cave man.
Thanks! That makes sense. Out of curiosity, did you measure the distortion spectrum at the end of the full chain (preamp + amp) once you found the individual settings on each that you preferred?
no but good idea. Nash
