I'm assuming this is a balanced design? Where are the inputs?
I'd really like to come up with a LU1014D design that can
drive my 4 ohm Carver Ribbons, maybe even with super-
symmetry. Would I need to parallel the VFETs and use something
rated higher than the IRFP240's?
I'd really like to come up with a LU1014D design that can
drive my 4 ohm Carver Ribbons, maybe even with super-
symmetry. Would I need to parallel the VFETs and use something
rated higher than the IRFP240's?
The input is at the connection between the 100k and 100 ohm resistors at the jfet input. This one would have no problem driving 4ohm speakers.
BR,
Anders
BR,
Anders
Anders,
Excellent concept,
I bit like a balance follower idea using the cascoded power Jfet.
Please keep us informed with your project.
Macka
Excellent concept,
I bit like a balance follower idea using the cascoded power Jfet.
Please keep us informed with your project.
Macka
Anders,
Have you received your LU1014D s yet?
I have mine already and also have some 800 watt Astec MVP
switchers with two of the 24V 15A modules per chassis.
I couldn't tell if your rails are +36v and -36v or +36v and -3v?
I still think that because of the impedance that I will need
to parallel about 4 of the FETs so that they are biased at
the most linear point as in Nelson's Zv9
Anybody else know anything about the Astec MVP series for
audio?
Have you received your LU1014D s yet?
I have mine already and also have some 800 watt Astec MVP
switchers with two of the 24V 15A modules per chassis.
I couldn't tell if your rails are +36v and -36v or +36v and -3v?
I still think that because of the impedance that I will need
to parallel about 4 of the FETs so that they are biased at
the most linear point as in Nelson's Zv9
Anybody else know anything about the Astec MVP series for
audio?
It does not appear to me to be biased heavily enough to handle a 4 Ohm load well. That's not too difficult to fix, though.
Grey
Grey
Project progression
Hi!
The amp was built the way it is shown in the first post and showed real promise sonically, it was running a bit hot with the heat sinks i had laying around though. To tackle that problem i decided to choke load it. This dropped the idle power by 50% AND it sounds better to my ears. I have also built one more jfet amp that you can see below, this one is not a transconductance amp and it is also quite happy as high bias class-B amp (500 mA or more). It sound is not quite as relaxed as the other two but it has more "grunt" and drive and i am using it now for bass only. The one below is the class-A version, in the class-B version i have removed the 0.5 ohm source resistors and inserted a bias supply in front of the output stage.
Regards,
Anders
Hi!
The amp was built the way it is shown in the first post and showed real promise sonically, it was running a bit hot with the heat sinks i had laying around though. To tackle that problem i decided to choke load it. This dropped the idle power by 50% AND it sounds better to my ears. I have also built one more jfet amp that you can see below, this one is not a transconductance amp and it is also quite happy as high bias class-B amp (500 mA or more). It sound is not quite as relaxed as the other two but it has more "grunt" and drive and i am using it now for bass only. The one below is the class-A version, in the class-B version i have removed the 0.5 ohm source resistors and inserted a bias supply in front of the output stage.
Regards,
Anders
Attachments
They are not really needed whith the tube input stage, driven as a buffer from my signal generator they where so i kept them just in case.
Anders
Anders
Hi, Anders
I hope you are not the same Anders in our office 🙂
I'm interested in this circlotron-ZV9.
The amp is operating quietly with no hum?
The 24V supplies require precision regulation?
Is it considered better than the X-ZV9 (Supersymmetry)?
Thanks,
I hope you are not the same Anders in our office 🙂
I'm interested in this circlotron-ZV9.
The amp is operating quietly with no hum?
The 24V supplies require precision regulation?
Is it considered better than the X-ZV9 (Supersymmetry)?
Thanks,
Anders,
How did you choke load it? Same as Nelson's Zv7-T, but with
the cap multiplier in Zv9 I'm assuming it would be between each side between the power rail and the cap multiplier? What did
you wind up using for chokes?
Grey, do you think 4 FETs per side would be about right
to get the operating points on Nelson's curve from Zv8?
Would some higher current (and possibly lower voltage)
HEXFETS be more suitable for a lower imp. load design
(esp. for the current source)?
The jfloat_tube2 Circlotron might be perfect for these
Astec SMPS's. There are two spare slots with a connector in
the back which supplies 380Vdc to the modules. I think I could
just drop that down, regulate and do a little more filtering
with some good results.
How did you choke load it? Same as Nelson's Zv7-T, but with
the cap multiplier in Zv9 I'm assuming it would be between each side between the power rail and the cap multiplier? What did
you wind up using for chokes?
Grey, do you think 4 FETs per side would be about right
to get the operating points on Nelson's curve from Zv8?
Would some higher current (and possibly lower voltage)
HEXFETS be more suitable for a lower imp. load design
(esp. for the current source)?
The jfloat_tube2 Circlotron might be perfect for these
Astec SMPS's. There are two spare slots with a connector in
the back which supplies 380Vdc to the modules. I think I could
just drop that down, regulate and do a little more filtering
with some good results.
The choke load is made up from the secondaries of Lundahl 1623PP, center tap to +15V.
Hum is not a problem at all since it will balance itself out.
BR,
Anders
Hum is not a problem at all since it will balance itself out.
BR,
Anders
about this thread ypu will find a similar circlotron from Andrea Ciuffoli:
http://www.diyaudio.com/forums/tubes-valves/213159-thorens-tem-3200-clone.html
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