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    Triode Electronics Audio Board

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    anbitet66

    Posts: 119
    Join date: 2009-12-23
    Location: Valley Stream, NY

    Triode Electronics Audio Board

    Post by anbitet66 on Wed Nov 03, 2010 11:07 pm

    Hi all,

    I'm completing an ST-70 clone from parts I collected from various places, and I'd like opinions on Triode Electronics 6AU6 audio board. I got one a while back, and populated it with parts from dynakit parts using metal film resistors and all stock values for resistors and capacitors. I'd just like to hear from anyone that used it as to how it sounds. I have more assembly to do, and at the rate of finding time, it may be a week or two before I finish.

    Thank you,

    Tony

    Bob Latino
    Admin

    Posts: 1970
    Join date: 2008-11-26
    Location: Massachusetts

    Re: Triode Electronics Audio Board

    Post by Bob Latino on Thu Nov 04, 2010 5:57 am

    Hi Tony,

    I have not heard the Triode 6AU6 board but personally I wonder why a 6AU6 tube, which is a 7 pin pentode RADIO IF tube, is even used in an AUDIO application. That tube was used in the IF strips of FM tube tuners (like the Dynaco FM-3) and color TV's of the 1960's. The 6AU6 is also known for being microphonic like 6DJ8/6922 type tubes. A triode tube, like the 12**7 tube family, IMHO makes a better driver tube for audio applications.

    Bob

    anbitet66

    Posts: 119
    Join date: 2009-12-23
    Location: Valley Stream, NY

    Re: Triode Electronics Audio Board

    Post by anbitet66 on Thu Nov 04, 2010 2:09 pm

    Bob,

    The Triode board comes in two flavors. Mine uses 2 6AU6's and either a 12AU7 or 12BH7. The other uses the 12AU7/12BH7 and 2 EF86's or 6922, 6DJ8, 7308, 6CG7. The circuit is the same as the original Dyna 7199x2 board. I have seen the 6AU6 used in audio applicaitons and it didn't sound bad, but since I got the board, I might as well try it.

    You have to understand at the time I collected the parts to build my clone, I hadn't heard of you, dynakitparts.com, just what was available at Triode and ebay. I finally overcame my fear of cutting the leads on the transformers to actually begin assembly. I'm now up to wiring the board to the chassis. Hope to find time in the next couple of weeks. I can then compare it to an original I've had about five years to see how the different tube types compare.

    Thanks for the reply,

    Tony

    anbitet66

    Posts: 119
    Join date: 2009-12-23
    Location: Valley Stream, NY

    Re: Triode Electronics Audio Board

    Post by anbitet66 on Mon Nov 15, 2010 11:13 pm

    Ok,

    Finally finished building the amp a short time ago. I let the ran the amp without any input for 30 minutes to allow the tubes to warm up before adjusting the bias. It was almost perfectly even at the middle of each pot. Had to replace a bum 6AU6 because of a slight hum.

    I set it up with a CD player and a pair of test speakers. I chose my all time favorite songs Blue Rondo A La Turk, and Take Five from The Dave Brubeck Quartet at Carnegie Hall. I almost can't wait for the tubes to break in! It sounds absolutly fantastic.

    Ebay: Chassis & Top Cover
    Triode Electronics: Transformers and SDS Labs board
    Electro Harmonics EL34's
    Shuguang GZ34
    RCA 12AU7
    Vintage 6AU6's

    Tony

    tubes4hifi
    Admin

    Posts: 1006
    Join date: 2008-11-30

    Re: Triode Electronics Audio Board

    Post by tubes4hifi on Tue Nov 16, 2010 1:33 pm

    I heard one of these about a month ago on a amp I was servicing for a customer.
    He had the EF86 version. It sounded OK, I'd place it about halfway between the old original stock unit and our VTA70 mod kit. Customer wanted to know if he should upgrade to our VTA70 board, and I told him to save $100 if he liked the way it sounded. On the other hand, if you are someone who would spend $100 on interconnects or on speaker cables, I would recommend doing our upgrade first because you will hear the difference.
    Yes, everyone is gonna say I'm biased. I'm not, but my tubes are . . . .

    "the path of least resistance is thru a vacuum"

    Bob Latino
    Admin

    Posts: 1970
    Join date: 2008-11-26
    Location: Massachusetts

    Re: Triode Electronics Audio Board

    Post by Bob Latino on Tue Nov 16, 2010 4:32 pm

    Everyone is entitled to their own opinion but I have to agree with Roy here .. The Triode board sounds noticeably better than the stock ST-70 driver board but (and again this is IMHO) it is not equal to the accurate sound reproduction of the VTA driver board.

    The Triode board has other disadvantages ..

    1. Does not have individual bias pots for each output tube and instead uses the old Dynaco bias system whereby you have two bias pots and use one pot for each PAIR of output tubes.

    2. Does not have its own power supply to run the board ON THE DRIVER BOARD. The consequence of this is that your main high voltage power supply be it a quad cap or an underchassis power supply must split duties. With the Triode board the power supply has to run BOTH the driver board AND the two output transformers. When you use the VTA driver board the on board power caps drive the board which leaves the quad cap (or under chassis power supply) free to power just the two output transformers.

    Bob

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