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Old 3rd May 2012, 03:32 AM   #1
batty is offline batty  Australia
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Default SUT earth lift implementation Q

I have a home made SUT that I wish to mod to add earth lift, but am unsure of how this is implemented.

Does the earth lift disconnect the outer of the output RCAs from the earth terminal? This makes most sense to me.
This would leave the chassis earthed at all times and the choice of floating or earthed RCA connectors.

Any help would be appreciated.

Steve.

*Title should read lift not life*
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Old 3rd May 2012, 01:35 PM   #2
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wutsa SUT?
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Old 3rd May 2012, 04:19 PM   #3
kevinkr is offline kevinkr  United States
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Step up transformer AKA "SUT" for a moving coil cartridge.

Not sure why you want the ground lift, but if you do this it might make sense to isolate the rca jack grounds from each other so that you get a differential input.
(dpst switch)

My experience with such attempts has been massively worse hum, but that may be system dependent.

If this is not what you are thinking and you indeed have RCA jacks grounded to the chassis, isolating the input and output RCA jacks from the chassis and grounding it separately is a good move. Also I generally find that keeping the left and right channel grounds separate from each other is a win as well. (Left channel RCA jack in and out grounds connected together, right channel RCA jack in and out grounds connected together. Not connected to each other, and chassis grounded separately.. Very quiet IME)
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Old 3rd May 2012, 10:19 PM   #4
batty is offline batty  Australia
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The reasoning behind the mod is that I have had an earth mod added to my RB250 so it no longer earths through the L screen but through a separate wire. I like your thinking about keeping L, R and chassis separate and may very well go down that path. Thank You for your input.

Steve
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Old 4th May 2012, 04:52 PM   #5
kevinkr is offline kevinkr  United States
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The earth mod on the RB250 is a worthwhile improvement, isolating the left/right channel, and shield grounds from each other in the SUT has proven worthwhile IME.
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Old 7th May 2012, 07:28 AM   #6
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For Rega stock wired tonearm, I wired it this way for an excellent result.
SUT faraday (if any) and body ground wires, outer shield in & output tied to chassis ground terminal.
Outer shield in & output should be lifted if used with other tonearms with separate ground wire.
Lastly, attempt positioning the SUT for least hum as it could pick up stray noise from transformers or other stuff.

I've read about a little tweak using a pair of 10ohm resistors in series to ground which puts the earth on another plane.
I did try this but yet measure if there's any real benefit to this. Grounding can be system dependent and ideal recommendations may not work well in some cases.
Relocation of SUT and phono stage maybe another course of action along with suggested SUT grounding techniques.
This is after my nightmare after numerous attempts to ground or reroute the SUT wires and TT grounding from numerous suggestions in various forums and discussions, only to realise the location of the phono and SUT is smack middle of lots of stray electrical noises where the SUT picks them up easily, worse if its nearer to my tube amplifier.

Last edited by coolmaster; 7th May 2012 at 07:41 AM.
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Old 7th May 2012, 07:37 AM   #7
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Default RB250

I have tried this and liked it . Some good ideas . Used with Denon 103 R . Is used with a RB 300 which was to be binned as the wiring had been wrenched out . Came free on a Dias turntable . Would say better than SME 5 to my ears .


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Old 7th May 2012, 07:55 AM   #8
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I'm a complete convert to SUT with a Denon or other MC cartridge after years with nothing but electronic stages.
If matched properly, the resultant sonics is awesome. I just don't see any electronic MC head amp having the SUT resolve. Its just the grounding can be an irritating issue to solve but if its gotten right, you're in for an enjoyable listen anytime.
I would also highly recommend the Rega tonearm to be rewired with better internal wires, separate ground wire, shielded twisted wire cable (lowest impedance mic cable?) all the way to the SUT, output interconnects also with the same cable type with the shield grounded on one end. It took me years to realise the phono department is best cabled this way. This applies to phono only, not line outputs. YMMG.
SUT rulez!

Last edited by coolmaster; 7th May 2012 at 08:02 AM.
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Old 7th May 2012, 08:11 AM   #9
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Default Denon 103

I like the 103 also . I find it a bit more difficult to set up . 2 .5 g . As it is spherical it is OK at that . Expert Stylus Ashted Surrry will transform an old 103 if you have one . Set RB 250 Bias by ear . If in doubt use the end groove and let the stylus gently drift to the inside . If the other way dynamics get lost

I have got a SME I can use if wondering so no hype . Lyra Argo suits that .

SME M series is very good if SME are reading this .
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Old 7th May 2012, 08:44 AM   #10
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I always feel the Rega tonearm (especially stock) isn't a great match with a Denon 103 or R model. After past experiences doing numerous swaps, my findings found the music slow and fatty compared to another good cartridge weighing in around 5-7grams (likely what Rega designer could have intended) which will certainly sound more upbeat and lively by comparison. The Denon is just too heavy for the Rega tonearm. The tonearm have to be modded for better compatibility as far as I'm thinking. The Denon weighs in at 8-9 gram+ with screws.
This is purely my view and not intended as offence to others who may find the combination healthy.
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