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    SP14 tube layout.

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    FearOfMusic

    Posts : 18
    Join date : 2019-01-07

    SP14 tube layout.  Empty SP14 tube layout.

    Post by FearOfMusic on Sun Mar 24, 2019 6:08 pm

    Hey. I’m playing with tube rolling in my sp14. I think that I read somewhere that the front tubes were more important to the overall sound and thus you can experiment with mismatching the pair front to back. Am I just making stuff up? If that is the case which pair is most important? The tubes oriented towards the back when looking down on the board or the front? Thanks in advance for any insight.
    Kentley
    Kentley

    Posts : 502
    Join date : 2015-03-06
    Age : 66
    Location : Worcester, MA

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    Post by Kentley on Sun Mar 24, 2019 6:51 pm

    Dear Fear:
    In this case, the common terminology of "front" and "back" tubes is entirely misleading. "Front" refers to tubes in the first position of the signal path; in the SP-14 these are the gain tubes and are, confusingly, the two on the LEFT of the board (viewed from the front). Most of us find that these two 6SN7s (or various equivalents such as Chinese CV-181) are the most subject to variation and have thus reserved our finest matched pairs for these holes. The two on the right of these are buffers and seem to be much less critical. Probably should use a matched pair, but they needn't be the same as your left pair. Exclamation
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    mijohn

    Posts : 59
    Join date : 2013-06-19

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    Post by mijohn on Sun Mar 24, 2019 7:39 pm

    Kentley and I must have been typing our replies at the same time and were very similar so I have edited most of mine, but I would add that in my experience that matching of the SP14 tubes is not absolutely necessary technically as you have a balance control for that, but I would choose same brand pairs.  BTW on the SP14 the two tubes at the front are one channel and the ones at the back are the other channel.

    Good to hear from you again Kentley, it's been a while since you posted here!
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    FearOfMusic

    Posts : 18
    Join date : 2019-01-07

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    Post by FearOfMusic on Mon Mar 25, 2019 7:25 am

    Thanks guys. This explains a lot. I had a tube get a little noise and moving it from front to back changed the noise from the left to the right channel. That’s when I first had the thought that I didn’t really understand the lay out of the tubes. Thanks again for the concise and detailed clarification.
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    Frank111

    Posts : 101
    Join date : 2015-02-23
    Location : Minneapolis/StPaul Area

    SP14 tube layout.  Empty Re: SP14 tube layout.

    Post by Frank111 on Mon Mar 25, 2019 12:57 pm

    I need to clarify this.  Looking from the front panel, the two leftmost tubes; front and back are for gain, and the two rightmost tubes; front and back are buffer?
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    audiobill

    Posts : 400
    Join date : 2014-03-13
    Location : Albany, NY

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    Post by audiobill on Mon Mar 25, 2019 1:17 pm

    yes
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    Frank111

    Posts : 101
    Join date : 2015-02-23
    Location : Minneapolis/StPaul Area

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    Post by Frank111 on Mon Mar 25, 2019 2:59 pm

    Thanks! Then I'm ok. I have two NOS Tung-Sol in the gain stages, and two RCA tubes in the buffer.
    deepee99
    deepee99

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

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    Post by deepee99 on Tue Mar 26, 2019 6:48 pm

    mijohn wrote:Good to hear from you again Kentley, it's been a while since you posted here!
    Yeah. Kentley, Where ya been?
    Kentley
    Kentley

    Posts : 502
    Join date : 2015-03-06
    Age : 66
    Location : Worcester, MA

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    Post by Kentley on Wed Mar 27, 2019 12:28 am

    Been busy transforming into my own grandmother. It's a lot of woik. What a Face

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