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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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PostPosted: 29 Dec 2016, 05:01 
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Joined: 08 Aug 2009, 03:11
Posts: 2100
Location: Chilliwack, BC
I have a successful service note on these dang things :thumbsup:

A big problem is the 2SK389, dual low-noise jFET. Unobtanium other than as fakes on Ebay or AliExpress. The only legit replacement is the LSK389, which is $40 each and isn't pin-compatible :hot:

After some research, the current production 2SK880GR (only available in SOT-23) is pretty much spec-on for it.

So, I bought ten, matched a couple for source-drain resistance using the continuity function (1.5mA source) on my DMM, dropped them on some SMD PCB adapters, installed, crossed my fingers and hit the power.....

PERFECT!

No need to adjust the bias resistors, nothing. They just worked :smoking:

Something of a sonic improvement over the other Modulus 3's I've listened to and just as low noise.

Cheers!

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-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


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PostPosted: 29 Dec 2016, 18:06 
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Joined: 04 Jun 2008, 20:59
Posts: 3463
Location: Arizona, USA
Neat, I hate it when something is no longer available. I have used SOT parts in place of others on occasion. Often I will use a short piece of a "surf board" to mount the SOT.

Good listening
Bruce

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Some of my DIY Tube Amplifier Projects:


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PostPosted: 29 Dec 2016, 22:40 
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Joined: 08 Aug 2009, 03:11
Posts: 2100
Location: Chilliwack, BC
Hi Bruce,

Check out Digikey 296-35646-ND. It has pads that I couldn't find on AliExpress.

Cheers!

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


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