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    sp14 resistor upgrade

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    tiguan

    Posts : 27
    Join date : 2014-07-23
    Location : Istanbul

    sp14 resistor upgrade

    Post by tiguan on Sun Mar 13, 2016 9:45 am

    Since I made, I saw using as original kit except mundorf silveroil
    Now I plan to upgrade resistors at signal line. R2 R4 R5 R6.

    R2 I plan to replace without zfoil.
    rest did not decide yet.

    I guess it will be enough but to be sure, will 1/2 watt be enough for those positions.
    Which brand would you recommend for 4,5 and 6.

    tubes4hifi
    Admin

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    Join date : 2008-11-30

    Re: sp14 resistor upgrade

    Post by tubes4hifi on Sun Mar 13, 2016 5:52 pm

    the SP14 is supplied with mil-spec Dale/Vishay resistors, not likely that using $5 resistors instead of 25c resistors will make an audible difference,
    but there are lots of high-end resistors to choose from! They can be 1/4w or 1/2w.

    tiguan

    Posts : 27
    Join date : 2014-07-23
    Location : Istanbul

    Re: sp14 resistor upgrade

    Post by tiguan on Mon Mar 14, 2016 10:39 am

    Thanks Roy sharing your opinion on changing resistors.

    You know it is in the spirit of DIY ing... My recent system is except power amp fully DIY. Rack, Turntable, Sp14, Le Pacific Phono Pre, ES SABRE 9018 Dac and Troels Gravesen Jensen 1071 speakers. Only power is Gamut D200Mk3.

    Periodically I make some changes, listen, sometimes go back, sometimes I like and keep the change.. So on and so forth.

    When there is nothing to do, try to discover something. This resistor issue is something like this. There is nothing to do and I am bored Laughing

    PeterCapo

    Posts : 386
    Join date : 2008-12-05

    Re: sp14 resistor upgrade

    Post by PeterCapo on Mon Mar 14, 2016 1:43 pm

    tiguan wrote: There is nothing to do and I am bored Laughing

    Man, wish I could say that!

    wanders

    Posts : 10
    Join date : 2016-03-16

    Re: sp14 resistor upgrade

    Post by wanders on Fri Apr 08, 2016 11:48 am

    tiguan wrote:
    R2 I plan to replace without zfoil.

    Curious to know, did you ever make the switch to Vishay z foil?

    Last year I built a Salas MC phonostage. Salas recommended Vishay z foils (Charcroft) for eight resistors In the signal path (four resistors/side in the dip switch controlled impedance selection circuit). At $16 for one z foil vs. $0.50 for the Takman REYs in place, I was skeptical. However I was intrigued, and given the he circuit design, I was able to set-up a direct a/b with the Takmans using only one z foil per side.

    I had three pretty sophisticated listeners over for the test and the result was unanimous: an audible and undeniable advantage for the z foils; not some kind of Golden Ear" kind of thing; say a 15% to 20% improvement in sound quality.

    But, I simply don't know if the same advantage would be present in the SP-14.

    tubes4hifi
    Admin

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    Re: sp14 resistor upgrade

    Post by tubes4hifi on Fri Apr 08, 2016 12:14 pm

    wanders,
    wow, I'm surprised you guys could hear a difference with a $16 each resistor. That could add up fast!
    I've used alot of Takman and PRP resistors, but never anything over 50c each,
    other than using some Caddock MP915 resistors in key parts of a phono pre (PH15) at $4 each.
    So if you or Tiguan or anyone else tries some expensive resistors in the SP14 or PH16,
    let me know !!
    I have heard universal praise from everyone that has paid $90 for a pair Mundorf silver-oil PIO capacitors.

    wanders

    Posts : 10
    Join date : 2016-03-16

    Re: sp14 resistor upgrade

    Post by wanders on Fri Apr 08, 2016 2:58 pm

    I've read some very favorable and objective reviews on the z foils; I'll post them if I can dig them out. For the Salas stage, the z foils were added after the Clarity MRs (albeit 400v). Obviously no opportunities on a phonostage for upgrades on selector switches or attenuators as in a preamp. Perhaps that would limit the cost/benefit potential of z foils in the SP14.

    vtshopdog

    Posts : 69
    Join date : 2015-07-11
    Location : UT, USA

    Re: sp14 resistor upgrade

    Post by vtshopdog on Fri Apr 08, 2016 3:58 pm

    wanders wrote:
    tiguan wrote:
    R2 I plan to replace without zfoil.


    I had three pretty sophisticated listeners over for the test and the result was unanimous: an audible and undeniable advantage for the z foils; not some kind of Golden Ear" kind of thing; say a 15% to 20% improvement in sound quality.

    But, I simply don't know if the same advantage would be present in the SP-14.

    I assume they were blind tested in the A/B and your friends did not know which component was playing when they evaluated?  DIP switch seems like an ideal and easy way way to do this.

    wanders

    Posts : 10
    Join date : 2016-03-16

    Re: sp14 resistor upgrade

    Post by wanders on Fri Apr 08, 2016 7:03 pm

    Yeah, it was as objective as I could make it. As noted, I was skeptical about the whole thing, but willing to risk $30 to buy two resistors for the test. After listening I ponied up another $100 to get the remaining six resistors.

    That's why I asked the question here: hoping somebody else was had taken the plunge.

    Tube Nube

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    Re: sp14 resistor upgrade

    Post by Tube Nube on Sun Apr 10, 2016 4:46 pm

    Gosh darn. Now if I were going to do a similar experiment on my sp 14, are particular resistors more important than others? Some in the signal path, Only resistors in the signal path? All signal path resistors?

    Actually, I know that a friend of this forum, Don Sachs, does these types of mods, so rather than do my own trial and error, I'd probably opt to hire him to do the job for me, if he thought the SP14 would benefit over the improvements Roy built into it at the outset.

    Still enjoying my pre amp, Roy. I expect to keep it forever . . . or until you better it. Which I hope you do. But not soon, ok?

    tubes4hifi
    Admin

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    Re: sp14 resistor upgrade

    Post by tubes4hifi on Sun Apr 10, 2016 11:27 pm

    R2 thru R8 are candidates for improvements, if Vishay/Dale mil-spec isn't good enough for you.
    Also, C3 is the only cap in the signal path, and thus the universal agreement that the $90 per pair Mundorf silver-oil PIOs are well worth using.
    For those of you that (claim) you can't read a schematic, R2 & R5 are grid resistors, for a small improvement I'd recommend Takman carbon films.
    R3 & R7 are strictly cathode resistors, and not considered in the signal path, although they supply current thru all the tubes.
    R4 & R6 are both cathode and plate resistors in the cascode configuration, and likely to make the most difference, I'd recommend PRP or better in those positions.
    Caddock MK132 resistors run about $5 each, and I can recommend their use in low level MC phono circuits.
    Kiwame resistors are HUGE 2w carbon film resistors that Japanese audiophiles like that cost around $1 each.
    Personally I think carbon films have a little more 'grit' in their sound than metal films.
    Rikens are another well known Japanese resistor (also carbon film) that run about $4 each.
    Shinkon resistors are another well known Japanese audiophile resistor, these are tantalum film, usually considered the best type for true hi-fi, around $4 each.
    Tepro is a newer brand I'm not famiilar with, a metal film resistor that looks very similar to the PRP resistors. Tepro is about $1.50 each,
    my personal choice from all of these is the 40c each PRP resistors (they are solid red, and were supplied with most of the PH15 phono preamps),
    or the Takman metal film type (REY line) which are very good for about $1 each, recommended.

    Maintarget

    Posts : 209
    Join date : 2013-02-10

    Re: sp14 resistor upgrade

    Post by Maintarget on Wed Apr 13, 2016 9:35 pm

    Great thread thanks for the input Roy
    Bob any resistor upgrade recommendations for your fine amp offerings?
    Thanks

    tubes4hifi
    Admin

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    Join date : 2008-11-30

    Re: sp14 resistor upgrade

    Post by tubes4hifi on Wed Apr 13, 2016 10:13 pm

    on a power amp the resistors aren't as critical, no reason to get anything better than Vishay/Dale,
    the R1-R2 input resistors and the 1K resistor on each output tube would be the most important

    Tube Nube

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    Age : 53
    Location : Calgary, AB

    Re: sp14 resistor upgrade

    Post by Tube Nube on Wed Apr 13, 2016 11:49 pm

    I've been reading on the DIY forum about non-inductive wire-wound resistors, and even about home brew rolling your own. Apparently carbon resistors are noisy, by comparison.

    I'm not trying to be difficult here, but I wonder if you've tried any commercially made versions, like Mills, and if you have thoughts about whether there's a benefit.

    Winding ones own wire resistors . . . sure sounds tedious, doesn't it?!

    wanders

    Posts : 10
    Join date : 2016-03-16

    Re: sp14 resistor upgrade

    Post by wanders on Fri Apr 15, 2016 3:21 pm

    wanders wrote:I've read some very favorable and objective reviews on the z foils; I'll post them if I can dig them out.

    I stirred the pot on this subject and promptly forgot to post any of the reviews mentioned. There are lots of opinion pieces on the web, most from people who have invested in the z_foils and are supporting their choices; but here is an article, dealing with resistors in attenuators, that seems more objective; The first link is to an Austrian website that contains an imbedded link to the article. (The second cite is the imbedded link in case you miss it.)


    http://www.higas.net/audio-hifi/audio-reviews/vishay-var-z-foil-review/

    http://www.blackdahlia.com/html/tip_67.html

    Tube Nube

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    Age : 53
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    Re: sp14 resistor upgrade

    Post by Tube Nube on Wed May 04, 2016 7:42 pm

    Good article. A bit "low rent" of him to invoke his professional credentials when writing on a topic on which he is a civilian, but hey, live and let live.

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