Preamp Volume/Balance question

[tonyd]

Originally Posted by kev313

I think that Art Dudley also briefly mentioned this phenomenon in his articles in Stereophile.

Found a relevant reference in AD's column in Stereophile Feb 2012. Commenting on the improved Haut-Brion level controls (ALPS vs Cosmos) he says '...among other things that allowed me to raise my preamp level to a range where channel-to-channel tracking is much better'.

[Labpro]

Fellow Shindo Fans,

I wonder if any of you have experienced mechanical transformer noise--loud enough to hear from the listening position?

I know it is not electrical, because other Shindo amps I've had in my system were perfectly quiet.

I've tried HRS dampening plates and platforms, but this did not help.

I'm open to suggestions at this point.

Thank you in advance!

Labpro

System Set Up:

Speakers: Coincident Pure Reference
Preamp: Shindo Giscours
Amp: Shindo Lafon GM-70 SET Monoblocks
DAC: Lampizator Generation 3, Level 4 DAC (24/192 capable)
Source: Naim Uniti Serve CD Ripper
Interconnect: Kubala Sosna Elation Speaker and Digital, Shindo Silver
Power: Shunyata Z-Tron Power Cables, Shunyata Triton Conditioner,
Room Acoustics: Shunyata Dark Field Elevators
HRS M3x Vibration Platforms with Nimbus Couplers and Dampening Plates
ASC Tube Traps, RPG Skyline Diffusers

[kev313]

Yep. From my Mr. T and when I had Sinhonias (original style). As it turned out, it was the outlet I had them plugged into which was running a bit hot. Moving everything to a different outlet fixed the problem.

[Labpro]

Thank you kev313!!

I'll try it tonight to see if that works.

I have 2 dedicated 15 amp lines in my listening room.

I'll let you know.

Thank you again!

[kev313]

Did it work?

[Labpro]

Hi Kev 313,

Unfortunately it did not help.

I'm working with my Shindo dealer to place some paper and dampening material around the transformer.

I'm also in touch with the folks at Synergistic Research. They have a new platform called Tranquility. It is suposed to eliminate noise from within the amp?

It's a long shot but they offer a 30 day in-home trial, so why not.

Thanks for asking....I'll keep you posted!

[kev313]

Do you have a tube cage on the amp (the original GM70's) which can be removed?

[Labpro]

I have the new GM-70 model.

I am familiar with the tube cage you are referring to.

It seems that the green "cage" on new GM-70 model uses a less rigid metal housing, so it may be more suseptable to vibration?

I spoke with Matt at Pitch Perfect Sound and did say that most amp mfg(s) use wax or other dampening materials, but Shindo does not use anything.

[Cellindo]

Dear Labpro.

High level of mechanical hum/buzz on large transformer can be caused by the presence of a small continuous voltage on your 110/230V supply.
I have this issue at home and my Naim equipment are buzzing a bit. The worst case was with a huge Karan amp (on loan) that uses inside two 1500VA transformers. The buzz/hum was unbearable dueing some moment of the day.
Either your electricity provider can fix it, or you would need to use a very large isolation transformer upfront of your system.

Check also the Shindo transformer (fixing torque and antivibration material). However if the real issue is a continous voltage on your mains supply, best case you will just attenuate the mechanical noise, but not completely eliminate it.

Good luck!

[tdelahanty]

If you donot have a small dc voltage on your lines, it's most likely the laminations (iron plates) inside the transformer vibrating. Some transformers are potted to avoid this. Shindo's transformers may or may not be potted.