I have rebuilt many of each of these models.
I can attest that the amount of time required to restore any of them is substantial.....but it is worth every minute.
The C-1 is the only commercial vfet preamp ever made and has a fantastic line stage. Everything else can be bi-passed. When required, the tome controls are quite effective to "tune out" a less than desired room....without the aid of a DSP.
side note:
I think at one point I saw someone here built a vfet preamp with Sony power vfets and that is a project I would be very interested in, but I can't seem to find it again.
I can attest that the amount of time required to restore any of them is substantial.....but it is worth every minute.
The C-1 is the only commercial vfet preamp ever made and has a fantastic line stage. Everything else can be bi-passed. When required, the tome controls are quite effective to "tune out" a less than desired room....without the aid of a DSP.
side note:
I think at one point I saw someone here built a vfet preamp with Sony power vfets and that is a project I would be very interested in, but I can't seem to find it again.
Hi Franz, I did some simulations around the 2SJ28 and 2SK60 for a line stage. The latter has half the power hence capacitance etc as the first one.
The 2SJ28 schema as far as I remember should resemble the Luminaria. Probably I changed the voltages a bit.
In the 2SK60 schema I went for choke, resistor and transformer load.
It should get more tweaking, to reduce the gain.
- I have a 5K/5K coupling transformer that allows 50 mA, glas-met-alloy. Both side have a centre tap. That allows me to reduce 6 dB without a high "cost".
Unfortunately I have not found a reliable parts seller yet.
Attachments
Same here except for the Sonys and agreed.
Truly an amazing piece of workmanship and absolutely 1 of a kind.
Since going a bit OT on VFET preamp, I clipped the feedback caps from the TA 4650 phono to make it more 'flat amp' w/sk63 small signal VFET (300 mv max input). So far, listening to it going through the 4650 preamp outputs gain stages with headphones using cell phone music source turned half way down.
Sounds marvelous through Sony MD hi eff headphones, even though the standard 4650 preamp out put is dog's breakfast for headphones @ 3K impedance. Doesn't sound even SS at all, sounds tubey, like DHT tube types. I'm sure there are frequency anomalies due to non-ideal headphone conditions. I will hook it up to larger system as preamp and see how it sounds with FW M2 into crossover-less panels.
Just for fun, not taking any of this seriously, just curious how the baby VFETs sound.
Sounds marvelous through Sony MD hi eff headphones, even though the standard 4650 preamp out put is dog's breakfast for headphones @ 3K impedance. Doesn't sound even SS at all, sounds tubey, like DHT tube types. I'm sure there are frequency anomalies due to non-ideal headphone conditions. I will hook it up to larger system as preamp and see how it sounds with FW M2 into crossover-less panels.
Just for fun, not taking any of this seriously, just curious how the baby VFETs sound.
Thanks ZM, I'll take a look : )
I'm also super curious what Papa has cooking up for these as well.
