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    Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice?

    slate1
    slate1

    Posts : 54
    Join date : 2017-07-26

    Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice? Empty Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice?

    Post by slate1 on Thu Mar 14, 2019 3:09 pm

    Anybody else running these?  Currently have Sovtek 6550's that I've been running for a few years and really enjoy them - just decided I'd like to try something a little different and see how it goes.

    Some additional details: have a Mullard CV4003 driver and a pair of RCA Cleartop 12AU7 phase inverters in the ST-120 and also have the Russian K40-Y PIO coupling caps installed.  Amp is fed by and SP-13 preamp with RCA Cleartop 6FQ7 drivers and Mundorf silver-oil PIO caps.  Phono pre is the PH-16x with Electro Harmonix 6922 drivers and Mundorf EVO coupling caps.  Speakers are Tekton Lore Impulse and almost all my listening is vinyl - classic rock, etc.

    Curious as to any advice on bias'ing, etc - planning on setting them up at 0.5 initially unless anyone advises differently.
    corndog71
    corndog71

    Posts : 702
    Join date : 2013-03-19
    Location : It can get windy here

    Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice? Empty Re: Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice?

    Post by corndog71 on Thu Mar 14, 2019 4:34 pm

    I set mine to 0.40 because they still sound great and it'll extend the life of the tubes. Some people say distortion is lower at higher bias points but I don't hear it.
    PeterCapo
    PeterCapo

    Posts : 699
    Join date : 2008-12-05

    Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice? Empty Re: Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice?

    Post by PeterCapo on Thu Mar 14, 2019 7:56 pm

    My concern with Chinese-sourced octal base tubes are the pins and the soldering.  I have yet to see one with very straight pins.  Some have good soldering, but others have bulbous solder at the ends of the pins.  If the pins are splayed-out and/or there is bulbous solder on the ends of the pins, the socket contacts could be deformed, and this could cause problems at some point.  I'd want to try to straighten the pins if needed and re-flow any bulbous solder.
    slate1
    slate1

    Posts : 54
    Join date : 2017-07-26

    Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice? Empty Re: Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice?

    Post by slate1 on Thu Mar 14, 2019 10:11 pm

    corndog71 wrote:I set mine to 0.40 because they still sound great and it'll extend the life of the tubes.  Some people say distortion is lower at higher bias points but I don't hear it.  

    Thanks! May just try that.
    slate1
    slate1

    Posts : 54
    Join date : 2017-07-26

    Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice? Empty Re: Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice?

    Post by slate1 on Thu Mar 14, 2019 10:14 pm

    PeterCapo wrote:My concern with Chinese-sourced octal base tubes are the pins and the soldering.  I have yet to see one with very straight pins.  Some have good soldering, but others have bulbous solder at the ends of the pins.  If the pins are splayed-out and/or there is bulbous solder on the ends of the pins, the socket contacts could be deformed, and this could cause problems at some point.  I'd want to try to straighten the pins if needed and re-flow any bulbous solder.

    Appreciate the input. Can’t exactly afford NOS 6550s it KT88s though. Have to go with what I can make work and hoping TADs reputation for selecting quality tubes will mitigate some of those concerns.
    MarcVBelgium
    MarcVBelgium

    Posts : 106
    Join date : 2013-12-06
    Age : 65
    Location : Antwerp, BELGIUM

    Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice? Empty Re: Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice?

    Post by MarcVBelgium on Tue Mar 19, 2019 3:33 pm

    Been using TAD 6550 STR in ST-120 for 4 years now. Great tubes !

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    Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice? Empty Re: Ordered a matched quad of TAD KT88-STR's to drop in the ST-120.... any advice?

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