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Lovoltech LU1014D power JFET

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#871
mrothacher said:
Dave:

What's the sleeve quantity, and will you sell an unmatched sleeve?

I've tried to ask this question on the store website, but it seems to generate confusion.

Thanks

Mike
Click to expand...

Sorry about that, I'm the only person that knows audio here. Most of the sales people would have no idea what you're asking. I'm sorry, but we aren't selling any unmatched (just trying to make sure we have them available for a while) they're going to last longer and go to more people this way. Thanks,

Dave
 
#876
Hi All,

I check on Deep Surplus site, they offer matching per Vgs, from 97 to 112.

I totally have no idea what Vgs is (this I will try learn about FET) but what is the advantage to have lower or higher Vgs?

Regards,
---
David
 
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#877
dw1, if you read the Zen V9 article, it mentions at the end about matching the R5 resistor to the Vgs of the LU.
Order one where you can get a 3-5watt resistor in that value. So a 1.12 would fit a 1.1 ohm resistor nicely, and a .97 would likely go with a 1 ohm resistor. Better matching for better distortion.
 
#878
We don't necassarily know the matching parameter details although, I saw that here somewhere eons ago. The FETs were likely matched at a low current in room temp. When the device heats up with 1.5A and 2.5V on it, the gate threshold will change lower than the spec'ed value. I beleive it is about 2.5mV/C. So, if the thing gets 25 degrees hotter than the temp during matching, your in circuit, in operation, threshold will be about 60mV lower than the rated value 😀
 
#879
Hi Tea-Bag... Thanks for your kind information...

I'm interrested to LU1014D after looking at EUVL's DAO heaphones on this thread http://www.diyaudio.com/forums/pass-labs/95841-mosfet-follower-headphone-amplifier.html

I'll read further the thread discussion whether I would need certain Vgs value or not... meanwhile, I think I must read Zenv9 article as well... (though my lack of , but only the basic, eletronic knowledge would make it hard for me 🙂 )

BTW, that Salas Direct Coupled B1..., do you mind tell me the thread link?

Thanks,
David
 
#880
@flg,
I think Nelson discussed this sometime back, that he measures the reading on those critters after 1,2,3 seconds at room temp after applying the voltage. So that's his method. I cannot speak for Deep Surplus. This was just a hack method of matching that seemed to work.
 
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