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Schiit LISST


captainbeefheart

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This is new to me, I didn't know they made a SS tube replacement.  Anyone care to speculate what's inside? 

 

I cannot find anyone that has put them on a curve tracer or did any testing to compare vs tubes. Has anyone here done any testing they would like to share with the rest of us?

 

 

My guess, it's literally probably just two LND150's (or something similar)  inside the can. That's all I can think of that would still perform similarly to a tube.

 

I use them regularly with good results.

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I dug this up from DIYaudio, supposedly from the original ad copy on the Schitt site (original webpage is down). I have no idea if this answers any questions or is marketing with few answers:

 

Okay, fine. We see how it is. What’s inside are two depletion-mode MOSFETs, together with minimal support circuitry to protect them against static, and to set the gain necessary for our products. There’s no “triodization” or other tricks applied to make them act like tubes, or have curves like tubes. They’re just good, linear, solid-state devices…in a can. When used in Mjolnir 2, they provide essentially the same topology as the original Mjolnir’s high-voltage JFETs, now simply at a much higher voltage, for even greater linearity.

 

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1 hour ago, BadChile said:

I dug this up from DIYaudio, supposedly from the original ad copy on the Schitt site (original webpage is down). I have no idea if this answers any questions or is marketing with few answers:

 

Okay, fine. We see how it is. What’s inside are two depletion-mode MOSFETs, together with minimal support circuitry to protect them against static, and to set the gain necessary for our products. There’s no “triodization” or other tricks applied to make them act like tubes, or have curves like tubes. They’re just good, linear, solid-state devices…in a can. When used in Mjolnir 2, they provide essentially the same topology as the original Mjolnir’s high-voltage JFETs, now simply at a much higher voltage, for even greater linearity.

 

 

Hahaha yes that's perfect!!   Pretty much exactly as I thought, two depletion mode Mosfets, I just happen to have a ton of LND150 which is a nice 500v depletion mode Mosfet in a standard TO-92 package. I use them all the time in guitar amplifiers where someone wants to add a buffer or another gain stage where adding another tube is not a viable option. They take up very little space and work well wired just like a typical common cathode gain stage except it's a common source gain stage with the Mosfet, or a source follower if I need a buffer for an effects loop. That's typically what i use them the most for is adding fx loops to guitar amps that don't have them.

 

I still would love to hear from someone that has experience with them but so far that about settles what they are in a general sense. I'd almost wager a bet they even use the LND150 as it's very popular and proven itself over the years for this sort of circuitry.

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  • 2 weeks later...
48 minutes ago, DirtyErnie said:

Big fan of the LND150, for the same reasons.

 

Have you done any measurements with them as a common source gain stage? I did at one point but must not have saved the files because I cannot find them on my computer.

 

This is mainly the reason I would like to find someone that has done any testing with the actual LISST device because when I tested the LND150 vs 12AX7 both setup like a typical common source/cathode gain stage they had different distortion profiles. They sound different to me with guitar vs a triode. This makes sense because the depletion mode mosfet will have output curves more like a pentode than a triode. It looks like Schiit uses them to replace triodes though? :blink2:  Anyone swapping tubes in their amps with these LISST devices should know they are going to change the sonic profile of that amplifier. I cannot find any information from Schiit showing output distortion of their amps between tubes and then with the LISST device. I'd wager it's going to make a pretty significant difference. The LISST should have a higher distortion content.

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I found some forum posts of a russian guy that put in a bunch of effort to get the LND150 to act like a 12AX7.  He ended up with a negative voltage source, a string of Schottky diodes or somesuch, and a few resistors feeding the Source to get the curves bent the same as a 12AX7.  There was something about the variable resistance - vs - current of the diodes that made them work right. He also had a resistor-diode series between Source and Gate to get the +v grid current happening for guitar distortion. Allegedly, his Marshall 2550 preamp sounded spot-on to an identical circuit card with a real 12AX7.

 

In my own stuff, I'm doing a source-follower with the diode-resistor 'grid-current' string to drive the tone stack on a 5F6A/JTM45/AC30 type of circuit, and a local-feedback stage to invert and add a few db of post-EQ gain for level-matching between channels. Seems to work pretty well.

 

If it was me doing HiFi, I'd probably do local NFB to get the gain where I wanted it, then maybe a split-load FET inverter/driver into local feedback power tubes, but that might not sound as 'good' to a lot of ears.  Haven't had enough time to play with electronics lately, have been playing with babies.

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