F-J-fet-2 ? 😀
By the way, for some time I have been running Zen V9 without feedback, and the performance was very good. But this seems to be too easy... I guess that Nelson has another trick up his sleeve 😉 😎
By the way, for some time I have been running Zen V9 without feedback, and the performance was very good. But this seems to be too easy... I guess that Nelson has another trick up his sleeve 😉 😎
Nelson Pass said:
Mr. Pass, there looks to be about 80+% less distortion from the original circuit with this new gain device. Now that's also very appealing to the other F amps using the 240 mosfet. Is this device easily obtainable for us simple folks?
Blues said:
No. The mystery part is already discontinued. There are other, newer
parts being sampled. The lead times are quite long, so it will be a
while before they can be tried. More news later.
Did I mention that they are also extremely expensive?
😎
Nelson Pass said:
Thank God you showed us amps with single gain devices.
With Zen and FW types I think us DIYers can take a deep breath and put our hard earned money up front for two power transistors.
Nothin ZM,
I heard a push-pull 845 11 years ago that was to die for.
Course back then using such high voltage was discouraged, at least for those of us who were not great DIYers.
I think these days, building a similiar creature would put me back some serious coin in iron. But I still think about it.
I heard a push-pull 845 11 years ago that was to die for.
Course back then using such high voltage was discouraged, at least for those of us who were not great DIYers.
I think these days, building a similiar creature would put me back some serious coin in iron. But I still think about it.
naah ....... that's just 1KV ; nutin' compared with usual 1.5KW FM x-miter , where 2.5KV are must ........
just put one hand behind back , when doing anything inside
seriously - toob amps have one good thing - output xformer ;
Papa's amps have another good "thing" - Papa himself
just put one hand behind back , when doing anything inside
seriously - toob amps have one good thing - output xformer ;
Papa's amps have another good "thing" - Papa himself
2SK2554
How about this MOSFET from Japan as a candidate? Much higher transconductance compared to IR devices.
How about this MOSFET from Japan as a candidate? Much higher transconductance compared to IR devices.
Nelson Pass said:
Is the Mystery part, Lovoltech LU1014D?
So is the replacement part supose to be more superior compared to Lovoltech?
fff0 said:
Can be interesting. I cannot find any transconductance figure published in the datasheet. Reading the Id-Vgs graph, I might say that the transconductance at 3V Vgs is about 35 - which is high.
I believe the search of the device should focus on finding a "Flat" transconductance behavior vs Vgs around the bias point. In the current F2, it is about 2.5A Drain current. Then a high transconductance figure will help to minimize the Vgs swing, so hopefully bring more linearity to the system. Certainly if we can reduce the bias current without harm to the performance, I would love to - energy saving is certainly a good thing. A new device might provide a chance to look at the bias point again.
The mystery part is from SemiSouth, the SJEP120R125.
1200 volts, 136 watts, 13 amps.
Already history, being replaced by something even more expensive.
I have an F2a article using it nearly ready for publication, and three
other prototype amplifier designs under test.
😎
1200 volts, 136 watts, 13 amps.
Already history, being replaced by something even more expensive.
I have an F2a article using it nearly ready for publication, and three
other prototype amplifier designs under test.
😎
We got the recipe: SJEP120R125+D9eII=A match made in heaven 😀
It seems that the new F2 and the Feastrex will make for a wonderful sound, but, for us mere mortals, it will be somewhat more difficult to acquire them
😎
It seems that the new F2 and the Feastrex will make for a wonderful sound, but, for us mere mortals, it will be somewhat more difficult to acquire them
😎