As it was mentioning here before, there is a big difference (more than usual) between in temperature in vfet casing and the nearby aluminum angle. Anything we can do to improve it? These are hottest transistors I see in Nelson’s designs so far, kinda scary.
Did you check to see if the vfet mounting screws are tight?
We are running the vfet at 34 watts which is over one third it's rating. It's going to be quite warm.
If it's a concern we can crank the bias down by raising the value of one of the 1.5 ohm resistors.
Yes.
I remember commenting to Nelson about the same thing once I had the prototype up and running, and his reply was essentially “don’t worry about it, they are metal can devices.”
Seems reasonable.
Ok thank you. Good with me then
nice can be for summer time when ZM hit 30°We are running the vfet at 34 watts which is over one third it's rating. It's going to be quite warm.
If it's a concern we can crank the bias down by raising the value of one of the 1.5 ohm resistors.
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@ PKI
Yes correct with B1K preamp at the inputs flip the speakers SE Vfet amp polarities
I might have missed something, but is this the case for stock B1K + Vfet too? With Nelsons standard input stage in the VFET?
Second question to everyone in Europe. Did you get your components yet? Mine are stuck in Germany since last weekend.
I like it. For what is worth, I think the "inverted" V looks much better than the parallel version.
ditto.
dave
First Class A, First Pass, First VFET
#50 is alive. It only took me all day (and into tomorrow) to complete it!
It is a lovely thing. The previous comments were spot on. It is utterly silent with absolutely no noise. The amp has a spooky, engaging presentation. It sounds downright fantastic on my test speakers. I was already surprised with something in a song I hadn’t heard before.
I still need to adjust the alignment of the chassis front plate. I confess I couldn’t get the bottom screws in place in the front plate as the final step of assembly. Naturally, that’s on me for going out of order in assembly.
I can not wait to set it up in my main rig tomorrow morning... er, later today.
Thanks again and again to Nelson, Jason, Mark, Jim... everyone that has supported this fabulous project.
I am a humbled and grateful man. It is very fortunate to have such a classy piece of audio history and excellence. Cheers.
Good luck to all the other builders!
#50 is alive. It only took me all day (and into tomorrow) to complete it!
It is a lovely thing. The previous comments were spot on. It is utterly silent with absolutely no noise. The amp has a spooky, engaging presentation. It sounds downright fantastic on my test speakers. I was already surprised with something in a song I hadn’t heard before.
I still need to adjust the alignment of the chassis front plate. I confess I couldn’t get the bottom screws in place in the front plate as the final step of assembly. Naturally, that’s on me for going out of order in assembly.
I can not wait to set it up in my main rig tomorrow morning... er, later today.
Thanks again and again to Nelson, Jason, Mark, Jim... everyone that has supported this fabulous project.
I am a humbled and grateful man. It is very fortunate to have such a classy piece of audio history and excellence. Cheers.
Good luck to all the other builders!
Attachments
Troubleshooting time!
I’ve lost the right channel.
What are the first measurements I should make to isolate the problem?
I don’t see any glaring faults, no magic smoke. The right heat sink was roughly the same temperature as the left after the channel went out. First it was lower in volume, then was progressively quieter until completely gone. Total operating time was about 30 minutes.
Thanks for any suggestions!
I’ve lost the right channel.
What are the first measurements I should make to isolate the problem?
I don’t see any glaring faults, no magic smoke. The right heat sink was roughly the same temperature as the left after the channel went out. First it was lower in volume, then was progressively quieter until completely gone. Total operating time was about 30 minutes.
Thanks for any suggestions!
Second question to everyone in Europe. Did you get your components yet? Mine are stuck in Germany since last weekend.
Everything arrived safely in Norway. Chassis last week, electronics yesterday. I'm deep inside the building process now. It is fun And the build guide is awesome.
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