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    Strange Tube Issue SP-14 DS2 Edition

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    aguaazul

    Posts : 57
    Join date : 2012-07-08
    Age : 58
    Location : Livermore, CA

    Strange Tube Issue SP-14 DS2 Edition

    Post by aguaazul on Wed Apr 11, 2018 12:07 am

    Intro Post:  http://dynacotubeaudio.forumotion.com/t3681-latest-addition-don-sachs-ds2

    When I 1st got the pre, I installed the tubes backwards… Shuguang Black Treasure CV181z (buffer) & Psvane CV181-TII (gain).

    When I actually read the directions, Don had instructed me to put the Black Treasure CV181z in the gain spot & Psvane’s in the buffer. When I did, I lost sound in 1 channel and the other channel popped with every volume step up or down click.

    Don say’s bad tube, hold tight, a new set of Black Treasure’s are in the mail. Cool.

    Tonight, I did the swap. A very strange issue presented itself.

    Tube Names for this explanation:
    Original Psvane CV181-TII: A1 & A2.
    Original Shuguang Black Treasure CV181z: A3 & A4.
    Replacement Shuguang Black Treasure CV181z: B1 & B2.

    So, I grab A3 & A4, pull them out. Move A1 & A2 to the buffer position, install the new B1 & B2. All is well.
    Of course, it’s A3 & A4 that are the problem.

    Later, leave B1 in the left (rear) spot, pull B2, install one of the problem tubes A3, everything is fine.
    Pull A3, drop in A4, everything is fine. I’m trippin’ here. After 156 dead shows, I may have lost a few ‘tiles’ on re-entry.
    Drop in A3 and A4 together, it’s back! Whew. Sound on A3, popping with the volume steps up and down.
    Switch R & L, issue follows the tube.

    I know what tube clicks (A4). I’m just wondering why it needs A3 to present the issue.

    ~~~~~~~~~~~~~~~~~~~~~~  
    The future. A4 is going back to Don. Due to this, I picked up a set of his stock Russian 6H8C’s for a backup set.
    What I thought I would try, since it’s hanging out here, is A3 (presumably the ‘good’ Shuguang Black Treasure CV181z) and try it out in our Latino St-120 with the 6SN7 to 6922 Adapter I just ordered from Tube Depot.

    ~~~~~~~~~~~~~~~~~~~~~~  
    Don’s in no rush to get the Shuguang(s) back. So, I thought I’d play. Do you think there is any skepticism to the QC on A3?

    ~~~~~~~~~~~~~~~~~~~~~~  
    If this is a cool story to tell…. This is the place to tell it!

    Cheers,
    Aguaazul


    Last edited by aguaazul on Wed Apr 11, 2018 12:08 am; edited 1 time in total (Reason for editing : Fix the intro link.)
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    jfine

    Posts : 151
    Join date : 2017-06-19

    Re: Strange Tube Issue SP-14 DS2 Edition

    Post by jfine on Thu Apr 12, 2018 11:03 am

    aguaazul wrote:Do you think there is any skepticism to the QC on A3?

    I think there is a QC problem with A3, A4, B1, & B2. IMHO.
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    aguaazul

    Posts : 57
    Join date : 2012-07-08
    Age : 58
    Location : Livermore, CA

    Re: Strange Tube Issue SP-14 DS2 Edition

    Post by aguaazul on Thu Apr 12, 2018 1:01 pm

    jfine wrote:
    aguaazul wrote:Do you think there is any skepticism to the QC on A3?

    I think there is a QC problem with A3, A4, B1, & B2. IMHO.


    As I read up on the QC group leaving Shuguang to become Psvane, that just may be what is going on.

    There is an outfit named Grant Fidelity, that pulls the best Psvane tubes. They have what they call the "Treasure Globe 6SN7-SE"  (GF Limited Special Edition) tube that is shaped like a light bulb.
    They are pretty proud of them too at $375 for a Grade A pair.

    @ $129 a pair for the 2 sets we got from Don, the great sound we have now, we'll listen to what we have.
    If the Shuguang die just out of warranty, I'll agree that QC is lacking and go with the Psvane's.
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    deepee99

    Posts : 1911
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Strange Tube Issue SP-14 DS2 Edition

    Post by deepee99 on Thu Apr 12, 2018 1:28 pm

    jfine wrote:
    aguaazul wrote:Do you think there is any skepticism to the QC on A3?

    I think there is a QC problem with A3, A4, B1, & B2. IMHO.
    Yep, plus all that tube-swapping may have weakened the sockets' contacts. That's like chasing a ghost. I'd re-tension the sockets before I blamed the tubes, but Chinese QC is a crap-shoot.
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    jfine

    Posts : 151
    Join date : 2017-06-19

    Re: Strange Tube Issue SP-14 DS2 Edition

    Post by jfine on Thu Apr 12, 2018 4:20 pm

    deepee99 wrote:
    Yep, plus all that tube-swapping may have weakened the sockets' contacts. That's like chasing a ghost. I'd re-tension the sockets before I blamed the tubes, but Chinese QC is a crap-shoot.

    The 6SN7 sockets, and the nine pin sockets, seem like they don't suffer from this near as much like the power tube sockets?
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    aguaazul

    Posts : 57
    Join date : 2012-07-08
    Age : 58
    Location : Livermore, CA

    Re: Strange Tube Issue SP-14 DS2 Edition

    Post by aguaazul on Thu Apr 12, 2018 10:26 pm

    jfine wrote:
    deepee99 wrote:
    Yep, plus all that tube-swapping may have weakened the sockets' contacts. That's like chasing a ghost. I'd re-tension the sockets before I blamed the tubes, but Chinese QC is a crap-shoot.

    The 6SN7 sockets, and the nine pin sockets, seem like they don't suffer from this near as much like the power tube sockets?

    The DS2 is built with Belton sockets, presumably they hold like a vice.
    I've felt loose upside down guitar EL-34 tube sockets, these are still pretty tight.
    I'll still take notice on loose pins on any tube / socket combo.

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