Dynaco ST-70 Upgrade

dbishopbliss · 19957

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Offline dbishopbliss

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Reply #15 on: October 24, 2014, 07:57:29 AM
Its been almost 4 years since I started this thread and I'm finally getting around to upgrading my amp.  I had the boards already, but I just ordered the parts to populate them.  Next Mid-Atlantic Bottleneck Meeting I will bring the amp.

David B Bliss
Bottlehead: Foreplay I, Foreplay III, Paramour I w/Iron Upgrade, S.E.X. w/Iron Upgrade
Speakers: FE127E Metronomes, Jim Griffin Jordan/Aurum Cantus Monitors, ART Arrays
Other: Lightspeed Attenuator, "My Ref" Rev C Amps, Lampucera DAC

Offline dbishopbliss

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Reply #16 on: October 28, 2014, 05:28:18 AM
I've been doing a little readying (dangerous I know).  Lots of people say that adding a grounded power cord to the ST-70 causes ground hum loops.  Has anyone done this? 

David B Bliss
Bottlehead: Foreplay I, Foreplay III, Paramour I w/Iron Upgrade, S.E.X. w/Iron Upgrade
Speakers: FE127E Metronomes, Jim Griffin Jordan/Aurum Cantus Monitors, ART Arrays
Other: Lightspeed Attenuator, "My Ref" Rev C Amps, Lampucera DAC

Offline Zimmer64

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Reply #17 on: October 28, 2014, 06:58:15 AM
I have built the VTA ST-70 and use a grounded power cord. Mine is dead quite. Hope this helps.

kind regards

Michael

Nelson Pass F5 Turbo V2, Quickie (mod), S.E.X. 2.1, Tubes4hifi SP14, Dynaco VTA ST 70, Tubelab SSE, Vroemen Diva Superiore ER4, Jordan JX92S VTL, 47 labs 0647 CD, Aqvox DAC, Rowen Absolute pre / psu / power amps, BG Neo3 / Betsy / Eminence A15 open baffles

Offline STURMJ

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Reply #18 on: October 28, 2014, 08:05:28 AM
I have built a Triode ST-70. Also has a grounded IEC, and no problems here either.


Offline Grainger49

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Reply #19 on: October 28, 2014, 08:24:01 AM
I've rebuilt 4 ST-70s and all got grounded power cords and no hum.  Two of those were almost scratch builds with Paully.

A frequent source of hum is the 10 Ohm resistor that floats the input's grounds from ground.


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