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The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


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    New Tubes4hifi product - the VTA-TDB time delay board

    Bob Latino
    Bob Latino
    Bob Latino
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    • Post n°1

    New Tubes4hifi product - the VTA-TDB time delay board Empty New Tubes4hifi product - the VTA-TDB time delay board

    Post by Bob Latino Mon Jul 11, 2011 4:10 pm

    New VTA product - the VTA-TDB time delay board KIT

    Tubes4hifi has a new product - the VTA-TDB which is a "time delay board" KIT for Dynaco amps. This board may also be used on any amp or preamp where you want to delay the application of high voltage. The time delay allows the tube filament heaters to come up before any high voltage is applied. The time delay is nominally about 17 seconds but may be adjusted for more or less delay at the discretion of the user. There are complete instructions for the assembly of the board and time delay alteration should the user decide to do so. In a stock ST-70 the board replaces lugs 5, 6 and 7 of the 7 lug terminal strip. In a VTA ST-70/ST-120 tube amp kit, the VTA-TDB replaces the 3 lug terminal strip. The VTA-TDB may also be easily retrofitted to any VTA ST-70/ST-120 tube amp kit.

    The board is 1 7/8 inches wide by 2 1/2 inches long. It takes about 1/2 hour to assemble and is powered by a 6.3 volt AC line taken off V2. When the board is powered up a RED LED lights up to show that the board has power. About 17 seconds after power is applied, a GREEN LED comes on and a quality Potter & Brumfield relay kicks in to apply high voltage to your amp. Another nice thing is that if you are in an area that has quick ON/OFF/ON power interruptions the board will automatically reset itself. In other words, if your power goes OFF and then ON again a split second later the board will automatically reset itself and no high voltage will be applied for another 17 seconds. Roy and I have been running this board in our own amps for some time now with no issues ...

    The board will soon be an option on all VTA ST-70 and ST-120 amp kits. The VTA-TDB KIT will sell for $35 + $5 shipping. Contact either Roy or myself for more information or to purchase a VTA-TDB kit.

    Bob

    New Tubes4hifi product - the VTA-TDB time delay board TDR


    Last edited by Bob Latino on Tue Jul 12, 2011 3:09 pm; edited 1 time in total
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    mantha3
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    • Post n°2

    New Tubes4hifi product - the VTA-TDB time delay board Empty Re: New Tubes4hifi product - the VTA-TDB time delay board

    Post by mantha3 Mon Jul 11, 2011 8:35 pm

    Does this handle the rectification of a GZ34? I thought it may as the tube rectifier was liked in place of a modern diode to do the slow warm up... What is the plus of this if you have a GZ34 to do the slow warm up? Just curious.. I love my ST120 so I'm interested in a 35 doller enhancement
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    Bob Latino
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    • Post n°3

    New Tubes4hifi product - the VTA-TDB time delay board Empty Re: New Tubes4hifi product - the VTA-TDB time delay board

    Post by Bob Latino Mon Jul 11, 2011 8:50 pm

    Hi Andrew,

    No - This is only a delay board - you still need a solid state or tube rectifier to plug into the rectifer socket. If you use a GZ34 tube rectifier IMHO you can get by without it. If you use a solid state rectifier like the Weber WZ68, which only has a 3 to 5 second delay, I think it is helpful. It would also be helpful if you have the quick ON/OFF/ON power interruptions. The minute you interrupt the power the board will resequence itself and you won't get any high voltage again for 17 seconds after the power comes back on.

    Bob
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    Roy Mottram
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    • Post n°4

    New Tubes4hifi product - the VTA-TDB time delay board Empty Re: New Tubes4hifi product - the VTA-TDB time delay board

    Post by Roy Mottram Tue Jul 12, 2011 2:44 pm

    this board is primarily intended for those running amps withOUT a tube rectifier, like most of the ST120 amps that Bob is selling with the Weber SS rectifier. If you have a tube rectifier you already have a slow turn-on.
    This board is a relay switch that will not apply the high voltage power to the amplifier until after the tube filaments are warmed up, as Bob mentioned typically the board has a 17 second delay and that can be changed by changing one resistor on the board.
    The can also be used in any preamp that has a solid-state power supply, such as the Transcedence Sound Grounded-Grid preamp, and most all of the AIKIDO preamps sold by Glassware.
    Another possible use is as a speaker delay mute in an amplifier or preamplifier.
    This is a very heavy duty industrial relay used for 270vac 3 phase and rated at 8 amps, with 1500v of isolation between the contacts.
    Similar delay circuits I evaluated for tube amp use had 240v contacts with 1000v of isolation and were physically larger, this is a great addition to your ST120 amp from Bob or for the M125 monoblocks. It can run on 6vAC or 12vDC.
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    avi.inc
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    • Post n°5

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    Post by avi.inc Tue Jul 12, 2011 6:03 pm

    Hi Bob
    Do you have a pik of this installed in a st-120
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    Bob Latino
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    • Post n°6

    New Tubes4hifi product - the VTA-TDB time delay board Empty Re: New Tubes4hifi product - the VTA-TDB time delay board

    Post by Bob Latino Sat Jul 16, 2011 2:46 pm

    avi.inc wrote:Hi Bob
    Do you have a pik of this installed in a st-120

    Hi,

    Below is a photo of the installation of a VTA-TDB time delay board into an ST-120 amp. An installation into an ST-70 would look pretty much the same. Thanks to forum member Jhoak for providing this photo ...

    Bob

    New Tubes4hifi product - the VTA-TDB time delay board VTA-TDBinstalledcropped


    Last edited by Bob Latino on Sat Jul 16, 2011 8:12 pm; edited 1 time in total
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    jhoak
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    • Post n°7

    New Tubes4hifi product - the VTA-TDB time delay board Empty Re: New Tubes4hifi product - the VTA-TDB time delay board

    Post by jhoak Sat Jul 16, 2011 3:23 pm

    OK guys... If you live in an area that has power blinkie-blinkies (like Central Flroida) every time the thunder rumbles AND you're using a SS rectifier this board is a MUST HAVE.

    I've only had it in place for a couple of hours and already it's shut the amp down 3 times because of short term drops or power sags.

    I don't know about you but I would MUCH rather have a 17 second interuption in the music than to see my Weber WZ68 (or anything else) spew its internals.

    If you live where there are power "issues" don't hesitate. Highly recommended!!!
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    Roy Mottram
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    • Post n°8

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    Post by Roy Mottram Mon Jul 18, 2011 1:43 pm

    now available, see link here: http://www.tubes4hifi.com/TDR.htm

    and Bob's link here - http://www.tubes4hifi.com/bob.htm#TDR
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