The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    Yuan-Jing 6N3 Tube Pre-amp from Parts Express

    Share

    anbitet66

    Posts : 132
    Join date : 2009-12-23
    Location : Valley Stream, NY

    Yuan-Jing 6N3 Tube Pre-amp from Parts Express

    Post by anbitet66 on Tue Mar 01, 2016 2:27 pm

    Anyone here interested in a little diy project?  Check this out: Yuan-Jing 6N3 Preamp

    I don't know how good or bad this pre-amp is, but at $22.80 I bought two of them.

    How bad could they be?  I guess I'll find out in a couple of days and I'll post back.  At the very least I'm hoping the circuit stops working when the tube is removed. scratch

    We'll see.

    Tony

    tubes4hifi
    Admin

    Posts : 1292
    Join date : 2008-11-30

    Re: Yuan-Jing 6N3 Tube Pre-amp from Parts Express

    Post by tubes4hifi on Tue Mar 01, 2016 9:01 pm

    uum . . . interesting . . .! It's got 4 transistors and runs on 12v. yeah, see what it does with no tube in there !!!

    anbitet66

    Posts : 132
    Join date : 2009-12-23
    Location : Valley Stream, NY

    Re: Yuan-Jing 6N3 Tube Pre-amp from Parts Express

    Post by anbitet66 on Thu Mar 03, 2016 2:53 pm

    Sigh, well,

    It arrived last night.  A quick look at the board confirmed the tube is in the circuit, but it is a cathode follower, no gain. Embarassed   OK, not a big deal, do more research next time.  The power supply must be 12VAC since the four transistors are used in a 30V+/- split supply and there is a 7805 voltage regulator for the tube heater.

    online schematic

    I'll see how it sounds this weekend.  In the meantime it does give me an idea to play with to maybe convert it to a gain stage.

    Still easily worth the $22.80 I spent.

    more to follow...

    Tony


    Last edited by anbitet66 on Thu Mar 03, 2016 5:35 pm; edited 1 time in total (Reason for editing : Changed my mind. So sue me.)

    GP49

    Posts : 735
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: Yuan-Jing 6N3 Tube Pre-amp from Parts Express

    Post by GP49 on Thu Mar 03, 2016 11:08 pm

    What is the input impedance? It could make a useful buffer to feed solid state equipment from a tube preamp phono stage that is sensitive to load impedance, like a Dynaco PAS.

    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Yuan-Jing 6N3 Tube Pre-amp from Parts Express

    Post by peterh on Fri Mar 04, 2016 2:57 am

    GP49 wrote:What is the input impedance?  It could make a useful buffer to feed solid state equipment from a tube preamp phono stage that is sensitive to load impedance, like a Dynaco PAS.
    Looking at the schematics input impedance is more then 1 Mhom
    I'll have to adjust this, input impedance equals the pot on input, whatever it has.
    But you may remove the pot and take the signal stright to the input caps, then input
    impedance will be more then 1 Mohm


    Last edited by peterh on Fri Mar 04, 2016 12:23 pm; edited 1 time in total (Reason for editing : Adjustment of answer, input pot discussed.)

    arledgsc

    Posts : 340
    Join date : 2012-11-30
    Location : SF Bay CA

    Re: Yuan-Jing 6N3 Tube Pre-amp from Parts Express

    Post by arledgsc on Fri Mar 04, 2016 12:08 pm

    I don't see the point if unity gain. You are just adding noise and distortion to the audio signal if using as a line level volume control. Other than an impedance buffer perhaps but tube cathode followers do not necessarily have ultra-low output impedance which can limit connecting cable lengths to very short ones with low capacitance.

    anbitet66

    Posts : 132
    Join date : 2009-12-23
    Location : Valley Stream, NY

    Re: Yuan-Jing 6N3 Tube Pre-amp from Parts Express

    Post by anbitet66 on Fri Mar 04, 2016 4:32 pm

    The pot measures 45k ohms. Not good for high impedance output devices. I will probably remove it and sub a 250k or 500k minimum of I think it's needed.

    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Yuan-Jing 6N3 Tube Pre-amp from Parts Express

    Post by peterh on Fri Mar 04, 2016 4:37 pm

    anbitet66 wrote:The pot measures 45k ohms. Not good for high impedance output devices. I will probably remove it and sub a 250k or 500k minimum of I think it's needed.
    Or remove it and substitute with 470k to ground.

    The pot and it's function could be used at the output instead, the tube will happily
    load 45k and output impedans is still decent.

    Sponsored content

    Re: Yuan-Jing 6N3 Tube Pre-amp from Parts Express

    Post by Sponsored content Today at 11:58 am


      Current date/time is Thu Dec 08, 2016 11:58 am