New Posts New Posts RSS Feed - Understanding Record Repro
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Welcome to the Graham Slee Audio Products Owners Forum

 

Open to all owners plus those contemplating the purchase of a Graham Slee HiFi System Components audio product and wishing to use this forum's loaner program: join here (Rules on posting can be found here)

This website along with trade marks Graham Slee and HiFi System Components are owned by Cadman Enterprises Ltd


Understanding Record Repro

 Post Reply Post Reply Page  <12345 12>
Author
Richardl60 View Drop Down
Senior Member
Senior Member


Joined: 04 Nov 2014
Location: Yorkshire
Status: Offline
Points: 1468
Post Options Post Options   Thanks (0) Thanks(0)   Quote Richardl60 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep 2017 at 2:27pm
I believe in a post last year someone suggests Jeff at Audiomods may have been a potential outlet for your line of thinking was that one of the ones tried?
Back to Top
BackinBlack View Drop Down
Senior Member
Senior Member
Avatar

Joined: 05 Feb 2012
Location: Hinton, N'hants
Status: Offline
Points: 2020
Post Options Post Options   Thanks (0) Thanks(0)   Quote BackinBlack Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep 2017 at 2:43pm
The interference from the connected world must also have a similar effect on all those naked glowing bottles in esoteric pre-amps and amplifiers. Is this why the perceived sound of themionic devices is becoming ever more fashionable in the audiofool world?


Edited by BackinBlack - 17 Sep 2017 at 2:44pm
Just listen, if it sounds good to you, enjoy it.
Back to Top
BAK View Drop Down
Senior Member
Senior Member
Avatar

Joined: 14 Mar 2010
Location: Kentucky, USA
Status: Offline
Points: 1744
Post Options Post Options   Thanks (0) Thanks(0)   Quote BAK Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep 2017 at 5:22pm
In his post about “The Connected World (2)...” Graham explained that very high frequency RF interference can be received at the phono preamplifier stage input at a level much higher than all magnetic cartridges' audio output, both MM and MC. And this RF interference can be as much as 14mV or more! 
 Graham Slee wrote: “The 14mV rms from each cartridge is far higher than what their 1kHz output suggests. The moving coil is the worst offender because when you relate 14mV to its rated output it is 10 times worse than moving magnet.

 We are told that we don't get interference using low output moving coil because of the low source resistance and low inductance, but both exist, and are sufficient to allow in much higher frequencies than when the myth was first started.

 Whatever we try and do in phono stage design the 'connected world' stamps on it its presence. That presence is an order of magnitude more for low output moving coil. It is the same magnitude as the upper end of the required dynamic range, and it cannot be removed. It therefore does what all high and low frequencies do when mixed together - they modulate!

 Moving magnet is still affected or inflicted with the same high frequency energy, because although it has high inductance it also has more capacitance due to more windings, and so as the scope traces show, it still couples the same high frequency interference to the phono stage input.

 The difference however, is a factor of ten. The amount of mixing is reduced by ten and so the highs are less accentuated, and the sound (in our 'connected world') is far more true to the original.”

 It comes down to the average MM audio output is 10x more than LOMC.
 (Avg MM = 3.0mV, Avg LOMC = 0.3mV)

 The following fact of physics supports this: 
<The more efficient transfer of energy from one form of energy to another form of energy will have more of the original information (or signal) transferred.>

   An energy transformation from mechanical energy to electrical energy happens when you play a record.
 More than one transformation is actually happening... 
Record speed turning the record groove... rotational mechanical energy; 
Needle stylus is actuated by groove vibrations... vibration mechanical energy; 
Those vibrations cause magnetic impulses induced in the coils... magnetic transient energy; 
Those magnetic impulses transfer into electrical impulses... induced electrical energy. 

 This electrical energy is the final output of a magnetic phono cartridge, and the greater this voltage is, the more of the original information is transferred from the record played… and with less noticeable interference.
 The frequency response and dynamic range are “balanced” against the highest possible output to give the desired result: a pleasing listening experience while preserving the original information. I say “balanced against” as there are always trade-offs because of limiting factors in all forms of energy.

 If I was to use any MC carts, mine would have to be HOMC only.
 Currently I use a 5.0mV MM and a 4.0mV MM. They sound better than my old 2.5mV AT14sa MM.


Edited by BAK - 17 Sep 2017 at 6:09pm
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!
Back to Top
Graham Slee View Drop Down
Admin Group
Admin Group
Avatar
Retired

Joined: 11 Jan 2008
Location: South Yorkshire
Status: Offline
Points: 16298
Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep 2017 at 7:09pm
After many hours (today) of modifying a Technics SL1200 MKII by connecting its two "-" terminals to the main earth "E". This is a photo of an unmodded arm base, but shows the respective terminals.



Then modifying the headshells of the Denon DL103 and Hana EL so the negatives go to the headshell metal work and not the arm wires...

Such that the arm and arm cable afford 360 degrees shielding except for the cartridge itself, I don't have anywhere as much interference.

And the arm earth wire is not used because it would form a hum loop.

Remember this?



Now it's like this...



Which shows how antiquated arm shielding is!!!

The way it should be. The way it was on 1950's HMV record players! Is continuous shielding from cartridge pins to amplifier input!

The interference is reduced by a factor of 3.5, and is much more manageable. It also sounds much better, without that piercing and deafening high frequency whizzer effect that is so annoying to me.

I can hear the wet finger running round the rim of a wine glass on Supertramp's Dreamer. I can hear the train carriages go by on the intro to Rudy. Completely hidden by the 'connected world' before now.

I have bass a plenty. Layered and with the right amount of muscle (some call it grunt).

More than that I have melody!

What stage am I using? The 'abandoned' Accession MC! Abandoned for being innocent!!!

There's no way I can release such a fantastic stage to an audience without a clue.

That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
Back to Top
Richardl60 View Drop Down
Senior Member
Senior Member


Joined: 04 Nov 2014
Location: Yorkshire
Status: Offline
Points: 1468
Post Options Post Options   Thanks (0) Thanks(0)   Quote Richardl60 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep 2017 at 8:44pm
Presumably this will depend heavily on the arm used and presumably of the material (if I am reading this correctly) using the arm as the earth?

Your findings being the case does this impact on the Accession MC more than the mm+EXP.?
Back to Top
Graham Slee View Drop Down
Admin Group
Admin Group
Avatar
Retired

Joined: 11 Jan 2008
Location: South Yorkshire
Status: Offline
Points: 16298
Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep 2017 at 9:06pm
The interference still exists whether it's an EXP or Accession. The Accession circuit is higher performance in a number of ways though. If given a clean signal it will amaze. If given a dirty signal you'll hear dirt.

As the traces show there isn't any interference worth noting much below say 50MHz, and that tells you that a standard size arm will shield up to the 30MHz I have always claimed - so long as it's metal. But as the traces show, it is wide open to all the 'connected world' frequencies, unless modified to provide proper shielding.

Obviously a plastic arm (carbon fibre) will not provide effective shielding against our 'connected world' so perhaps Andrew's suggestion of a lead box would come in here LOL

I often wonder what the hi-fi industry is about. From my standpoint much of it looks like utter BS. Of course, some of it is gold-plated, but it's still a Censored
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
Back to Top
Richardl60 View Drop Down
Senior Member
Senior Member


Joined: 04 Nov 2014
Location: Yorkshire
Status: Offline
Points: 1468
Post Options Post Options   Thanks (0) Thanks(0)   Quote Richardl60 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep 2017 at 9:27pm
Graham to be clear and in the absence of a detachable headshell what would the wiring look like, +ves use the standard arm wiring so what would the -ves look like?

Sounds a bit like jump starting a car with a dead battery!

Also given I have an eye on an Audiomods V; would this not work here as it has a rega armtube?
Back to Top
 Post Reply Post Reply Page  <12345 12>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.01
Copyright ©2001-2018 Web Wiz Ltd.

This page was generated in 0.125 seconds.