The 12AX7WS is a more modern design of the same concept, for guitar heads of course.
A company in California (probably one guy) made a complete set of solid state replacements for the tubes in the Collins S-Line. Skytec Tubesters. Seems like that was back in the 70's. I'm sure I've seen solid state 1L6's and 5AR4's.
https://www.qsl.net/kh6grt/page4/tubesters/tubesters.htm
Win W5JAG
https://www.qsl.net/kh6grt/page4/tubesters/tubesters.htm
Win W5JAG
Yeah, some of the single ended ones come stock with a huge value cap right after the rectifier tube. I've seen 470uf electrolytic as C1. No surprise people complain that the rectifier tube only lasts 6 months.
jeff
Creating a solid state device to be the same as a vacuum tube reminds me of something . . .
A successful animal husbandry professor wanted to start with a new name for an animal, by cross breeding.
He decided to name it an abalcroc.
Now, what to crossbreed, ah, he had it . . . an abalone and a crocodile.
What did he get . . . a croc of baloney.
We have tubes, we have solid state devices, often in the same amplifier.
Why do we need a crossbreed, a solid state tube?
I suppose we make solid state devices that work as a tube substitute for the same reason that we climb the mountain . . .
Because the mountain is there to climb, and because we can climb the mountain.
If I could, I would climb K2 . . . forget about Mt. Everest (K1), hundreds have done that.
A successful animal husbandry professor wanted to start with a new name for an animal, by cross breeding.
He decided to name it an abalcroc.
Now, what to crossbreed, ah, he had it . . . an abalone and a crocodile.
What did he get . . . a croc of baloney.
We have tubes, we have solid state devices, often in the same amplifier.
Why do we need a crossbreed, a solid state tube?
I suppose we make solid state devices that work as a tube substitute for the same reason that we climb the mountain . . .
Because the mountain is there to climb, and because we can climb the mountain.
If I could, I would climb K2 . . . forget about Mt. Everest (K1), hundreds have done that.
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Some experiments here from UK Vintage Radio
ECC83 from a broken ECC81 plus two FETs
ECC83 from a broken ECC81 plus two FETs
I still find this concept fascinating, due no doubt to my lack of deeper electronics knowledge, thanks! I have an etracer tube tracer, I wonder what the curves and characteristics of this LND150 dual triode "tube" might look like compared to other dual triodes? I know this is all an intellectual exercise, expecting drop-in "SS tube" replacements to work in all contexts is far fetched. But in a simple example that splits a dual triode as input stage followed by a concertina inverter... How far fetched can it be to have a real vs. "fake" plug in option; as a part of the whole tube rolling experience?. Two amber grain of wheat bulbs could impersonate the filament.
@lhquam LU1014 modulated cascode, real curves here:
https://www.diyaudio.com/community/threads/lu1014d-modulated-cascode.397230/post-7307694
https://www.diyaudio.com/community/threads/lu1014d-modulated-cascode.397230/post-7307694
Unfortunately the LU1014 is unobtainable now along with the beast 2SK180. It doesn't get any more tube like than this. https://jandkaudiodesign.blogspot.com/2018/06/sit-amplifier-with-2sk180.html
I still have maaaany available...
https://www.diyaudio.com/community/threads/ld1014d-lu1014d-matched-by-vgs-and-curve-tracing.381338/
@Windcrest77
AGD does this. They take a GanFET Class D circuit, stick it in a KT88 like tube enclosure, light it up like a Christmas tree and voila it sells like hotcakes.
Yes, I’ve heard it, sounds like a Class D amp with some 2nd harmonic thrown in for good measure (ie looser bass, open midrange, slightly rolled off highs). But overall quite good although… expensive.
https://agdproduction.com/
Of course their design is custom and the tube is just for marketing, not backwards compatible with any other tube design. Somewhat different than what you are talking about.
Best,
Anand.
AGD does this. They take a GanFET Class D circuit, stick it in a KT88 like tube enclosure, light it up like a Christmas tree and voila it sells like hotcakes.
Yes, I’ve heard it, sounds like a Class D amp with some 2nd harmonic thrown in for good measure (ie looser bass, open midrange, slightly rolled off highs). But overall quite good although… expensive.
https://agdproduction.com/
Of course their design is custom and the tube is just for marketing, not backwards compatible with any other tube design. Somewhat different than what you are talking about.
Best,
Anand.
I saw the AGD room at Axpona two years ago. I asked a few questions, basically saw that it was nothing more than a circuit in a bottle, so I giggled and left. But at an "audiophile" show occupying 500 demo rooms in a hotel I'm sure they had many takers among the folks who buy $14,000 power cords!
Not worried by the RIAA network but by all other parameters 😎
Main problem being that a FET is not a triode equivalent but a Pentode.
That alone kicks the chessboard hard and sends all pieces flying all over the room.
You will never ever make a full 12AX7 plug-in replacement by straight substitution.
It can be done, (curve slopes, plate impedance, biasing at various idle currents, etc.) but it takes effort, it is not straightforward at all.
jcalvarez.
Long ago, when dual gate MOSFETs first came out, I never noticed any application that "Triode Wired" it.
But that long ago, I did not notice any Pentodes and Beam Power tubes that were used in Triode Wired mode, either.
(but we know that "Triode Wired tubes" preceded JFETs, MOSFETs, and dual gate MOSFETs.).
I wonder if anybody still has any dual gate MOSFETs. I remember them as small RF devices.
Has anybody Triode Wired them, and used a curve tracer?
What are the curves like in that mode?
Long ago, when dual gate MOSFETs first came out, I never noticed any application that "Triode Wired" it.
But that long ago, I did not notice any Pentodes and Beam Power tubes that were used in Triode Wired mode, either.
(but we know that "Triode Wired tubes" preceded JFETs, MOSFETs, and dual gate MOSFETs.).
I wonder if anybody still has any dual gate MOSFETs. I remember them as small RF devices.
Has anybody Triode Wired them, and used a curve tracer?
What are the curves like in that mode?