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    Stepped attenuator for VTA ST70 and VTA MkIII Octal

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    solderblob

    Posts : 46
    Join date : 2018-05-20
    Location : Placerville, California

    Stepped attenuator for VTA ST70 and VTA MkIII Octal

    Post by solderblob on Fri Jun 08, 2018 3:07 pm

    I'm ordering a Goldpoint stereo attenuator for my system.  The setup is Turntable/DL-103 cartridge to step up transformer to Hagerman phono preamp to attenuator to amp.  I'll use both my ST70 with VTA board and my MkIII with VTA Octal board.

    My existing attenuator is about 4kohms (if I measured it correctly).

    What size attenuator should I get?

    Thanks for any assistance.

    Dave
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    arledgsc

    Posts : 491
    Join date : 2012-11-30
    Location : SF Bay CA

    Re: Stepped attenuator for VTA ST70 and VTA MkIII Octal

    Post by arledgsc on Sat Jun 09, 2018 9:50 am

    I use a 50K ohm Gold Point Atten. in my ST-120 amp to keep the input impedance as "low" as practical and be near the customary 47K ohm load seen on a lot of consumer electronics. 100K ohm would work as well and believe that is the value Bob ships with amp kits. I would not go lower than 50K or higher than 100K.
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    solderblob

    Posts : 46
    Join date : 2018-05-20
    Location : Placerville, California

    Re: Stepped attenuator for VTA ST70 and VTA MkIII Octal

    Post by solderblob on Sun Jun 10, 2018 10:18 am

    Thanks arledgsc,  50K sounds good and seems like the most popular size on Goldpoint's site.

    Dave
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    solderblob

    Posts : 46
    Join date : 2018-05-20
    Location : Placerville, California

    Re: Stepped attenuator for VTA ST70 and VTA MkIII Octal

    Post by solderblob on Mon Jun 18, 2018 11:40 am

    Just an update.  I talked to Arn at Goldpoint and he suggested 25k Ohms as the best overall choice so that's what I went with. BTW, Arn is very helpful and answers his phone or returns calls.

    The short story is that it's a great attenuator and sounds amazing.  24 steps are plenty and normal listening is with the knob right around 12:00 o'clock.

    The longer story is that I first wired it up with all the grounds connected together.  Don't ask why, but I figured grounds are ground...So when I put it in my system, there was no bass, no dynamics, and the channel balance was off.  I looked at how I had wired my old attenuator and it was the same with all in/out grounds connected to both grounds of the attenuator.  And I had used that setup for years, occasionally experiencing some channel balance issues which I had blamed on the crappy attenuator switch/wiper or my interconnects. etc.

    I couldn't find any info anywhere on how to deal with wiring the grounds but yesterday I finally went ahead and separated the grounds to each respective channel and voila', it worked.  So I graded myself a dumbass for wiring it wrong but a genius for fixing the mistake!

    So now my system with the VTA MkIII octal mod is sounding dynamic, detailed, and musical with great bass.  Listening to my record collection again...

    dave

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    Re: Stepped attenuator for VTA ST70 and VTA MkIII Octal

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