The IXCP10M45S is sold as a current regulator so the usual mosfet parameters are not shown in its datasheet. It could be a normal depletion mosfet but I wouldn't take the risk of using it as a follower. It cannot be used as a CCS in the PSU, the current to feed the zener is 1.7mA, and the IXCP10M45S has a minimum of 2mA. It could be used as a CCS (10mA) in the follower stage, but I don't know about the result. It would be a $3 saving each. Again, I wouldn't take the risk.
I bought a bunch of 10 IXTP01N100D and selected them for the minimum |Vgs| to use as followers and maximum |Vgs| to use as CCSs.
An STF3LN80K5 (cheap but good) can be used as a follower (also as a voltage regulator in the PSU), but the midpoint will go down around 5/6V because of its positive Vgs. This is only cosmetic, with no impact on the sound.
Before some ask: I tried the DN2535/40, as a CCS, but it seems below a certain current it doesn't work. Some in this forum say its sound is not the best.
I bought a bunch of 10 IXTP01N100D and selected them for the minimum |Vgs| to use as followers and maximum |Vgs| to use as CCSs.
An STF3LN80K5 (cheap but good) can be used as a follower (also as a voltage regulator in the PSU), but the midpoint will go down around 5/6V because of its positive Vgs. This is only cosmetic, with no impact on the sound.
Before some ask: I tried the DN2535/40, as a CCS, but it seems below a certain current it doesn't work. Some in this forum say its sound is not the best.
I am thinking to use two J113 parallel as the follower.
When diying BabyHue tube power amp, two mosfets with samll Ciss(300p) and Crss(0.85p) were used as buffer (follower with BJT CCS) between two tube stages(12AX7 and KT88). Subjectively speaking, I think it sounded not like a tube amp(I might be wrong).
If just from dadasheet, JFet has much smaller Ciss and Crss is comparable. I think it is worth trying.
When diying BabyHue tube power amp, two mosfets with samll Ciss(300p) and Crss(0.85p) were used as buffer (follower with BJT CCS) between two tube stages(12AX7 and KT88). Subjectively speaking, I think it sounded not like a tube amp(I might be wrong).
If just from dadasheet, JFet has much smaller Ciss and Crss is comparable. I think it is worth trying.
I wouldn't use J113 because of its Vds. The Tre used the ZVNL120A. In the Talia I used the IXTP01N100D which has a low Ciss. However, The Ciss is negligible because the follower works in common drain, and the previous stage only sees a couple of pF.
The regulator is similar as marigno's virtual battery. I like to use LED array as a portion of reference voltage as in Salas DCSTB power supply. By shorting out some LED segments, the output voltage can be adjusted. As show in the photo, 3 LED have to be jumped out to get 60VDC voltage.
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Very good job!
The DN2540/TO220 used as CCS in the virtual battery works at 1.5mA. Does it work well? Mine didn't with a so low current, while the IXTP01N100D didn't have this problem.
Do you like the sound?
The DN2540/TO220 used as CCS in the virtual battery works at 1.5mA. Does it work well? Mine didn't with a so low current, while the IXTP01N100D didn't have this problem.
Do you like the sound?
Although my DIY is the original one, but the designed PCB can be used for multiple configuration, like Talia by adding or omitting some components. GND is start style like described in marigno's design. The output delay circuit is different. I used a version I did and tested.
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@wwwtttwww You're working hard on the WOTS Tre! But you didn't say about its sound. What do you think?
After one week listen, adjustment, listen, change, it the time to report my first impression.
This is indeed a very excellent preamp. I have built few kinds of preamps, so far it is the one of two I like at most(another one is M7 tube preamp).
Also my personal impression, BF256B is slightly better than BF244B, so I use BF256B in my final configuration.
One thing is worth to mentioning is that ZVNL120A is very hot. I think I will increase its Rss to 3k or so reduce Pa.
This is indeed a very excellent preamp. I have built few kinds of preamps, so far it is the one of two I like at most(another one is M7 tube preamp).
Also my personal impression, BF256B is slightly better than BF244B, so I use BF256B in my final configuration.
One thing is worth to mentioning is that ZVNL120A is very hot. I think I will increase its Rss to 3k or so reduce Pa.