SemiSouth boiler room

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My partner Jim continues to improve the solid-state "tube" based on the SJDP120R085 SemiSouth SiC JFET. Here's an image with a full set of four installed in his Fender Twin guitar amp. Accomplished musicians that have played the amp with the latest version of the "tube" say it sounds amazing.

We are working up new data and a studio quality demo tape. More soon!
 

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My partner Jim continues to improve the solid-state "tube" based on the SJDP120R085 SemiSouth SiC JFET. Here's an image with a full set of four installed in his Fender Twin guitar amp. Accomplished musicians that have played the amp with the latest version of the "tube" say it sounds amazing.

We are working up new data and a studio quality demo tape. More soon!

Doctor Mazzola
Thanks for the update. I'm very interested to hear the result of your work. Will the audio file(s) be downloadable do you think?
The amp really looks cool fully equipped with your SiCfet creation!
 
My partner Jim continues to improve the solid-state "tube" based on the SJDP120R085 SemiSouth SiC JFET. Here's an image with a full set of four installed in his Fender Twin guitar amp. Accomplished musicians that have played the amp with the latest version of the "tube" say it sounds amazing.

We are working up new data and a studio quality demo tape. More soon!

To build something like this for my bass, I'd need 400W bare minimum. Is this design easily scalable up to 400W?
 
My partner Jim continues to improve the solid-state "tube" based on the SJDP120R085 SemiSouth SiC JFET. Here's an image with a full set of four installed in his Fender Twin guitar amp. Accomplished musicians that have played the amp with the latest version of the "tube" say it sounds amazing.

We are working up new data and a studio quality demo tape. More soon!
Looking forward to hearing it. Will there be an A/B with real 6L6's in the same amp with the same guitar?
 
Speaking of the 085 device, was a model ever generated for it. If so, point me there...

I don't have one specific to the SJDP120R085, but when I want to model one I take the following SJEP120R100 model and set Vto=-5. That should work in a pinch. While your at it, change the model to SJDP120R085 to keep track of it.

.model SJEP120R100 njf
Vto=1
Beta=10.5
Lambda=2m
Vk=2k
Alpha=20u
Is=1f
N=3.4
Isr=1n
Nr=6.8
Cgd=1n
Cgs=755p
Pb=2.6
M=0.8
VtoTC=-2m
BetaTCe=-0.6
Xti=86
*$
 
Doctor Mazzola ,

How is your work on the instrument amplifier going?

Great question! I've been meaning to update this thread for awhile. My partner and I are currently working on the "Generation 3" design. The original posts were for the Generation 1 design, which was quite good, but we felt could do better. Generation 2 was born from that testing and exceeded the expectations of our professional guitar player tester. He spent an afternoon with the Fender amp loaded with Generation 2 SiC tube replacements, and was literally blown away. He said the issues he had had with the Generation 1 design were resolved and that he preferred the SiC tube replacement to the original 6L6 vacuum tubes. Will others agree with him? Only time will tell once we start getting product out to people. We are considering a crowd-funding release.

So why is a Generation 3 design needed? We want the resulting SiC tube replacement to be a tube in virtually all things that matter to the amplifier socket they go into. The Generation 3 design improves the grid characteristics seen by the amp. When that's completed and after thorough testing, we will consider our options for getting a product out there so folks that want to give it a try can see for themselves. That is why the crowd funding model is on the table.

Thanks for asking and stay tuned!
 
Dr. M -

I think I remember you saying that the Infineon jfet was a lateral device. I've looked at its specs, and it has a much lower theta jc than the R085 (bigger die) and much, much more gate capacitance. Comment?

You are correct. The lateral JFET design forces a much bigger die for the same current rating. The jc may be lower, but you can get the same thing from a lower Ron with the vertical junction JFET. And in power electronics switching applications, lower resistance means less heat generated to be gotten rid of anyway. Indeed, the smallest die per Ron rating is still the vertical junction SiC JFET, despite improvements with the SiC MOSFET. Now, with linear amplifiers you may crave the lower jc because you are setting the power dissipation from other considerations, like the "sweet spot" of the amplifier! Everything in electronics is a trade off.

But among things important to linear amplifier enthusiasts, you noticed the big problem with the lateral channel JFET, which is that the much larger die size is reflected in much larger "input" (mostly gate-source) and "output" (mostly drain-source) capacitances. I love the vertical JFETs in power switching application circuits. Its like switching with ideal switches compared to the alternatives, like silicon MOSFETs. For the linear amp guy, it means less THD from the non-linear features of those same capacitances, and an increase in the ceiling on the preamp output impedance that will drive the input of the power amp.
 
I don't have one specific to the SJDP120R085, but when I want to model one I take the following SJEP120R100 model and set Vto=-5. That should work in a pinch. While your at it, change the model to SJDP120R085 to keep track of it.

.model SJEP120R100 njf
Vto=1
Beta=10.5
Lambda=2m
Vk=2k
Alpha=20u
Is=1f
N=3.4
Isr=1n
Nr=6.8
Cgd=1n
Cgs=755p
Pb=2.6
M=0.8
VtoTC=-2m
BetaTCe=-0.6
Xti=86
*$

Thank you brother
 
Great question! I've been meaning to update this thread for awhile. My partner and I are currently working on the "Generation 3" design. The original posts were for the Generation 1 design, which was quite good, but we felt could do better. Generation 2 was born from that testing and exceeded the expectations of our professional guitar player tester. He spent an afternoon with the Fender amp loaded with Generation 2 SiC tube replacements, and was literally blown away. He said the issues he had had with the Generation 1 design were resolved and that he preferred the SiC tube replacement to the original 6L6 vacuum tubes. Will others agree with him? Only time will tell once we start getting product out to people. We are considering a crowd-funding release.

So why is a Generation 3 design needed? We want the resulting SiC tube replacement to be a tube in virtually all things that matter to the amplifier socket they go into. The Generation 3 design improves the grid characteristics seen by the amp. When that's completed and after thorough testing, we will consider our options for getting a product out there so folks that want to give it a try can see for themselves. That is why the crowd funding model is on the table.

Thanks for asking and stay tuned!

Doctor Mazzola,
Thank you for the update! I am very interested in what you are working on. Please keep us up to date on your crowd funding aspect. Do you have an idea of the expected life of your solid state tube versus the 6L6? If your device affords far greater life than the vacuum tube it replaces and great sounding performance I think it has great potential.
 
Great question! I've been meaning to update this thread for awhile. My partner and I are currently working on the "Generation 3" design. The original posts were for the Generation 1 design, which was quite good, but we felt could do better. Generation 2 was born from that testing and exceeded the expectations of our professional guitar player tester. He spent an afternoon with the Fender amp loaded with Generation 2 SiC tube replacements, and was literally blown away. He said the issues he had had with the Generation 1 design were resolved and that he preferred the SiC tube replacement to the original 6L6 vacuum tubes. Will others agree with him? Only time will tell once we start getting product out to people. We are considering a crowd-funding release.

So why is a Generation 3 design needed? We want the resulting SiC tube replacement to be a tube in virtually all things that matter to the amplifier socket they go into. The Generation 3 design improves the grid characteristics seen by the amp. When that's completed and after thorough testing, we will consider our options for getting a product out there so folks that want to give it a try can see for themselves. That is why the crowd funding model is on the table.

Thanks for asking and stay tuned!

Doctor Mazzola,
Thank you for the update! I am very interested in what you are working on. Please keep us up to date on your crowd funding aspect. Do you have an idea of the expected life of your solid state tube versus the 6L6? If your device affords far greater life than the vacuum tube it replaces and great sounding performance I think it has great potential.
 
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