Nude Turntable Project

I went back to my original set-up from 2 years ago and guess what........
No feedback.....🎉😍
Then it dawned on me......
Has it dawned on you.....😜❓

Fascinating. A simple scientific inquiry. Well done `Ö´

Regards, Halcro: Intriguing. Echo chamber? If so, Dynamat or loose insulation might address the issue.

Peace,

Pretty TT plinth Henry. Your architecture background is evident. This emperor definitely has new clothes. :^0
No longer Nude - can we expect a thread name change..hah hah. Your DV is riding really low or is that just the camera angle ?
Cheers

Henry - yes - electrical feedback, not structure born. Try putting the whole thing in the granite bowl with the motor cover attached.
I think if Steve McCormack were running a direct drive he would have launched "WonderNappies" along with his TipToes.

Halcro, your original looks like my current, except that I use 4 cones (one dead center) and no cups.

So what did you discover - does the tin can actually help?

Dover wins the Kewpie Doll...🎉💇
When I changed the support of my Victor to the steel cradle two years ago, I removed the flimsy perforated metal screen surrounding the 'guts'.
Well it turns out that this metal screen was acting as a Faraday Cage for the electrical emissions from the motor power supply.
Without the screen absorbing and neutralising this energy.....the cartridge apparently picks up the 50/60Hz emitted frequency at very loud amplification levels (I can't imagine that the platter is vibrating at this frequency?).
This is why there is no feedback issue with my primitive (sorry Aigenga 😏) original support system.
And yes.....when I place the Victor into the granite cradle with the screen attached.....no feedback 😃‼️

This however gives me a dilemma.....I would prefer not to have the screen attached as there are audible benefits without it. I also don't believe the screen is as effective (being tight up against the granite inner wall) as I believe a Faraday Cage should have both sides of the metal screen in free air?
I have orderred Mu Metal sheet and wondered if this was a possible alternative to the Faraday Cage?
Is it OK to wrap the power supply transformer in Mu Metal or will it get too hot?
Would it be better to line the inside of the granite cradle with the Mu Metal instead (or also)....or am I doomed to using the metal cover forever?

Hi Chris,
It may be the camera angle....?
I think the Dyna is riding just fine...😎
I hate removing the word 'Nude' from any sentence......😰

Halcro, the can on my tt-101 is heavily damped with bituminous automobile noise suppression sheets, it is also wrapped with a fat rubber band and as I said I use a cone (more like fat cylinders with sharp points) dead center to further drain it. So while it looks primitive compared to the granite clerical collar (but far less primitive than letting it all hang out) it is actually fairly sophisticated.

I use a mu metal shield under the platter, covering the motor.

Halcro - if the cover is tight, then I would run an earth wire to the cover and then just push it into the cylinder leaving a gap at the top such that it doesn't touch the main TT. As long as the cover is grounded to discharge any electrical buildup it works. You could spray some damping compound on the inside of the cover if you want to get rid of any mechanical noise.

It is also possible that the tonearm & tonearm cabling could be picking up rf from the motor.

A small point on earthing - I usually find I get a lower nose floor if I run the TT earths ( i.e. chassis, motor etc ) to ground through the power cable to wall if possible and run only the tonearm earth to the phono/preamp. In a single ended system noise from grounding or shielding is effectively in the signal path.

Halcro
Is there a secondary issue here?

" ..a low frequency drone begins and then increases in volume.."

Could there be acoustic feedback following the initial EMR problem?

Cheers

The cover is grounded by three screws to the frame of the tt. Also, originally there was a ground cable attached to the cover. I have grounded my tt via a new 3 wire pc that replaced the original non-grounded 2 wire line. The new ground-wire is attached to the frame via the circuit-board stand-offs. Also, I highly recommend damping the cover well, including using a footer at the center to drain it.

I get zero feedback even when it is too loud to be in the room, and my left speaker is about 2 feet away from the turntable.

Richardkrebs,

Is there a secondary issue here?Could there be acoustic feedback following the initial EMR problem?

I think you're right....
When I play music at loud volume containing 30-60Hz bass drum beats (like Cream's 2005 Royal Albert Hall Concert or Copland's 'Fanfare for the Common Man' Ref. Recordings)....this 50/60Hz feedback loop can take hold.
At the same time I can feel the vibrations in the supporting shelf and in the granite cradle...😱
As the shelf is directly over the Vandersteen subwoofers, this seems like air-borne sound converting into structure-born feedback.
But why only recently...and why is the Raven not similarly affected as it is identically situated?

Halcro
Have you tried testing the resonance characteristics of the granite pipe?
The material does have a tendancy to ring like a bell.

Also by "identically situated" do you mean that you placed the Raven at the same place on the shelf as previously occupied by the Victor?

Does the Raven have a suspension?

Hi Richard

The Raven does not have suspension. It does however have OEM Stillpoint feet

Henry,
If you will recall some years back in my experimentation I was running three tables side by side. I had each set up well on the concrete slab. Making nice music in their own different and unique way.

The test for structure feed back was to lower the needle on a still record un mute and crank the volume slowly. Then jump up and down beside each table searching out air pockets in the poured concrete. You're not a true audiophile until you have danced with your turntable.

I then brought out the bad boy. The Acutex 420 str. As naked a cartridge as there ever was. And I teamed it up with wiring that was unshielded except for its own poly covering. What followed was interesting.

The Jean Nantais Lenco exhibited a drone like noise. If I remember it was almost mechanical sounding. In talks with JN, I added an extra ground from the motor to the plate but to no avail. I was unwilling to make further mods to his table so that was the end of the road.

The Technics SP10 II made noise and required an extra ground. It was added from where the bolts goes into the casing and then into the preamp. This cleaned things up and it was quiet. Almost.

My former modded thread drive TNT/SDS drive with pneumatic suspension. An absolutely black silence, as black as the table itself. It revealed a veil in the music that the SP10 was making.

As we say - You don't know what's there, until you hear "it" removed.

So the 420str is a very good test cartridge - imo. If things pass with that cartridge they can only get better from there. Cheers

Have you tried testing the resonance characteristics of the granite pipe?

Granite pipe 8^0

When I started this  exercise over six years ago, I began rather crudely with the Victor TT-81 simply supported on cones.
MODEL 2010 
Unsatisfied with the 'flexure' of the motor-unit about the cones, three years later I designed an independent stainless steel cradle to support the now 'fully nude' TT-101 motor unit...
MODEL 2013 
Two years after that, still unsatisfied with the vibrational and torsional movement possible with the flimsy steel frame.....I designed a cradle cut from a solid block of black granite and then polished.
MODEL 2015 
Despite the fact that my floor is a reinforced concrete slab cast on the ground and the turntable is supported on a thick laminated shelf cantilevered from a solid brick wall.....I know that there are low-frequency vibrations in all building structures and materials particularly materials under stress like suspended floors, shelves and equipment stands.
When materials are in stress (particularly tensile stresses)....they actually emit low-frequency vibrations between 2-10Hz and these frequencies are easily transferred through turntable plinths, motor units, spindles, platters, tonearm mounts and thus into the tonearms, cartridges and vinyl records themselves.
So for this year....I invested in a Herzan TS-140 Active Isolation for my turntable/armpods combination.
MODEL 2017 
This stand is designed for electron microscopes and contains numerous electronic actuators which isolate to 0.5Hz in all six degrees of freedom.
HERZAN 
So what is the difference.....?
Exactly what I expected.....but still almost unbelievable 💥
The improvements at first seem subtle but are all-encompassing....
Be aware.....this has NO effect on frequency response,
But every frequency SEEMS affected by suddenly having a purity, transparency and 'body' that was somewhat 'cloudy' before the Herzan.
There is absolutely no strain or stress to any music at any volume and as you turn up the volume...so you want to continue turning it up 🎶
I thought perhaps the bass would be deeper or more solid but no.....the bass seems unaffected but all the clarity and delicacy is bestowed upon the midrange and the highs with a singular crystallinity emanating from every cymbal, string, flute and horn.
The first casualties of unwanted vibrations in the analogue domain are the tiniest molecular-sized groove modulations which contain the most ephemeral informational DNA.
Qualities like body, soundstage, spatial depth and positional indications are simply smeared when other unwanted vibrations are present.

So it's been an illuminating and rewarding journey...
I hope you all enjoyed it with me....
Am I finally done?
I think so 😎

Hi Halcro,

 Congras on the Herzan! An amazing piece of hardware we TT owners all wish for.  I have the Minus K and I have noticed the biggest difference in using this passive isolation platform is when the volume is turned up.

You summed it up perfectly “There is absolutely no strain or stress to any music at any volume and as you turn up the volume...so you want to continue turning it up”

 The degree of effectiveness in using an active or passive isolation platform largely depends on the amount of air-borne energy in the room. My TT sits fairly close behind my left speaker and sub. Prior to using the Minus K in my system, on one occasion, I was able to make my Talea/Titan jump off the record groove when playing  “1812 overture”.  In using the Minus K, the playback sounds consistently beautiful regardless of the volume setting.

The beauty with the Herzan platform is as simple as “plug & play”. The Minus K is a passive system that requires careful set-up (centring the spring, and is load sensitive) to maximize performance.      

halcro
Congrats on your latest acquisition, were you able to find
one locally?

Thanks Norm,

Five years ago after Thuchan listened to my system, he suggested I look into an isolation stand and I investigated Minus K (I didn't know about Herzan).
The trouble with the Minus K (as you would know) is that it requires the load to be more or less centralised and evenly spread.
It can't cope with isolated individual loadings. It's large-scale wobble movement was also rather alarming....😱
I'm sure it suits your turntable perfectly. Can you remind me what turntable you have mounted on it?

The degree of effectiveness in using an active or passive isolation platform largely depends on the amount of air-borne energy in the room.

That's a common assumption many make but I doubt its validity.
Just think about it.......with the Minus K stand, you have not decreased the amount of 'air-borne' energy one iota and as you turn the volume up.....you are certainly increasing it.
Yet isolation stands (of all types) cannot prevent the air-borne energy in the room from interacting with the turntable plinth, platter, tonearms and cartridges directly.
The fact is, the air-borne energy is not of a sufficiently low frequency (and amplitude) to be a direct consequence.
More likely that some of this air-borne energy is absorbed by the rooms structure (including supporting shelves and stands) and transferred via 'structure-borne' feedback.
That's why the Minus K and Herzan stands were designed to combat 'structure-borne' vibrations of the lowest magnitude.

The Herzan is certainly a 'plug & play' design as you say.....
I just hope the electronic actuators and motor controllers have a long and durable life....🙏🏽

Thanks totem,

Herzan USA is the Distributor for Australia (go figure).....so all dealings were directly with Reid Whitney and Tim Rather who were most helpful.
The unit was shipped via FedEx (when the custom top-plate was ready) and was here in three days....😀

As I understand it, if something untoward were to occur, it would most likely need to be shipped back to Switzerland where it was designed and built?

halcro,

"The fact is, the air-borne energy is not of a sufficiently low frequency (and amplitude) to be a direct consequence."

My experience was different.  My tt is placed on a shelf within an alcove along one wall and built into the walls.  The alcove is 60" wide.  Originally I had the tt at the far right end of the shelf which placed the arm/cartridge very close to a corner.  One day I happened to lean over the tt while music was playing at a moderately loud level, I was amazed by the amount of low frequency build-up I heard in that corner.

So after thinking about this I moved the tt closer to the left end of the shelf where the arm/cartridge would be near the mid-point of the length of the shelf.  That was one of those "you notice the distortion once you remove it" experiences.  The sonics were definitely cleaned up, at least noticeably in the bass range.  And so I would always avoid placing a tt in a corner, just to minimize air-borne energy.

Mechanical transmission is another story.

Interesting experience pryso......
I wonder if you've tried experimenting with placing the stylus in a stationary groove whilst slowly increasing the volume?
Does any feedback develop and if so....is it different with the turntable on the left of the alcove to when it was positioned at the far right?

Halcro,

Thanks for your very informative post. I had a similar experience with a Vibraplane, which I still use.

I have heard the Herzan is effective far beyond the Vibraplane and Minus K. Did you happen to try either of those and if so could you compare to the Herzan?

I have followed this thread and am very happy to see this great conclusion.

Best Regards,

Jim Perry

halcro,

No, I didn't try a stationary grove test.  After moving the table away from the corner the increased clarity when playing moderately loud music (I probably never exceed 90 dB, unlike some) was proof enough I didn't feel the need to test any further.  Noticeable feedback (howling) was never a problem although I assume the problem was low level feedback from the pickup being in a high pressure zone area.

Thanks for the kind words Jim,
Some think that the Herzan is an 'overkill' for our application......and at the prices for their 'active' bases, it is an option few would contemplate.
I haven't tried any other bases although I wanted to try the Minus K many years ago.
It simply wasn't suited to my isolated turntable/armpods arrangement and I concentrated on making my cantilevered supporting shelf more rigid in the meantime.
I'm sure your Vibraplane gives you most of the same improvements I've described.....
It's hard to describe all the subtle effects one can hear once ALL spurious vibrations are removed.....
Most of the records I own where the high-frequencies at times became strident and even sometimes unbearable.....are now listenable. It doesn't mean one is not aware of 'hot' recording or mastering techniques.....it just clarifies exactly what is occurring.

Glad you enjoyed the Thread Jim and thanks once again.

Regards
Henry

Cost of course is relative.......
Any serious analogue lover who is in the market for an $8,000-$15,000 LOMC cartridge......should seriously consider a Herzan Active Vibration Isolation System and a $300 vintage MM cartridge instead......
There is really no comparison IMHO....🙈

@halcro at risk of seeming like a stalker (after getting the Palladian on your tip) I've reached out to a Herzan about adding a TS-150 to my rig. As I suffer from a very seismically active environment I think it may be just the ticket

FWIW, You can find Herzan isolation tables for sale on eBay as industrial surplus items, and in that format they can be quite affordable.  (They really ARE most often used for electron microscopes or to isolate sensitive industrial processors of one kind or another.)  Problem is they are often so massive as to be unsuitable for our sort of use. But once in a while.....

Seems to me also that I once figured out Herzan make the MinusK or the Vibraplane, or both.  

@lewm -- agreed re eBay, if you have room for some industrial tech the AVI series could work well -- for example this is a nice one

However what’s great about the TS-150 (except its price) is how compact (18kg, 450mmx400mmx78mm) it is and hence how easy to slot onto an existing stand or in my case wall mount

Hahaha folkfreak 😝
I think the Herzan looks like a perfect fit for your turntable.
And yes Lew....it's hard to find the compact TS Series of Herzan on EBay