Internal Tonearm wire recommendations

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Michael L
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#16 Re: Internal Tonearm wire recommendations

Post by Michael L »

vinylnvalves wrote: Thu Jul 16, 2020 1:30 pm Stop putting negative vibes on silver.... I have a mechanical telephone exchange in the mother-in-laws barn full of plessey type 72 switches I plan to strip and sell on ... when times get even leaner in the aerospace industry :(
Would that be a PABX or UAX? I spent some time as an apprentice in Strowger exchanges. I remember feeling rather nervous around the batteries in the large exchange in Birmingham called Central. Quite a noisy place too. Later, I spent time upstairs in Birmingham A repeater station. I don't what valves were in the repeater amplifiers they were decommissioning but there were a great number of units. It had the longest RDF (repeater distribution frame) in Europe apparently. Ah the memories:)
vinylnvalves
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#17 Re: Internal Tonearm wire recommendations

Post by vinylnvalves »

I don’t know anything about exchanges... it’s just something my late father-in-law acquired about 30 years ago, it’s the size of an upright fridge-freezer. It was threatened to be given to the scrap man, I said no I want it, there is a lot of wiring to remove to get to switches... I think it was an internal office exchange - which came out of an office block when refurbished.
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shane
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#18 Re: Internal Tonearm wire recommendations

Post by shane »

I used Satcure Litz wire to rewire my 774 which is dirt cheap and worked a treat, but I’m not sure if he’s still trading:

http://www.satcure.co.uk/accs/page18.htm#litz

I also replaced the red plug with a five pin version to allow me to wire it balanced to my SUT. This was available as a kit on eBay but again I haven’t seen it on there for a while. It’s all proprietary bits though so it wouldn’t be hard to replicate:

https://www.google.co.uk/search?sxsrf=A ... 67P-LVWK7M
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vinylnvalves
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#19 Re: Internal Tonearm wire recommendations

Post by vinylnvalves »

Thanks for the link... it looks as if he’s still trading. Regarding the connector. I am a big fan of not having unnecessary connectors in the signal path so will be running the wires back to the phono amp. I have already got/made a red connector block - well really a grommet on a 3D printer. Whether I join/ solder some screened cable to the internal wires or just run the fine wire back to the xlr plugs I haven’t decided. One of my bugbears where I think we have gone backwards is not being able to get small phono amps which fit under the plinth, as everyone wants a flashy box on show, it did keep the wiring run short. My cranfield rock even has a space for one, think Max marketed a Lentek battery powered one under this own brand. I suppose back in the 80’s the choice of phono stages was limited. I did used to put the SUT under there, when I use to use them.
Morgan Jones
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#20 Re: Internal Tonearm wire recommendations

Post by Morgan Jones »

All this talk of types of wire and nothing about how it should be used? It's a horrible fiddly job, but this is how I make it easier. I do the job once or thrice a decade, and that's still too often.

The internal wire has two jobs. It must get the signal from cartridge to arm base without picking up hum and it must add minimal friction/stiction. I usually use SME wire I bought in 1984. I used fancy Litz stuff for the arm on my 301, but it's horrible to get the enamel off. By the way, the industry term for silk "wrapped" is silk served.

Hum: Tightly twisted pair per channel. The loose four-wire twist usually used is very poor at rejecting hum.

Friction/stiction: The wire might need to revert to the loose four-wire twist as it passes through/past the pivot. It will settle to the lowest friction/stiction configuration, but you need to give it some help. Smooth/polish all surfaces/edges. Think gas-flowing an engine's valve ports.

Earth bond: Even if the bearing is metal to metal it's not a reliable long-term electrical contact. You need an earth bond from moving part of the bearing housing to fixed. Spend some time converting 6BA/M3 solder tags into 10BA/M1.6 tags. Chop off the big end and work with what's left. Good needle files help (Vallorbe; available from Cookson Gold). A diddy modeller's vice is useful too.

Seeing what you're doing: I use Optivisor #3. They really work, and I have one in the lab, one in workshop.

Bags of light: Powerful (>2W single chip) LED torches are now cheap as chips. Fit one in a microphone tripod to shine it on the work.

Soldering: Small tip on your (temperature-controlled, please) iron. 0.45mm silver-loaded (2-3%) solder intended for SMDs. Fine solder is more easily melted by the small tip and you can better control how much you use. The best joint occurs in <2s and uses minimum solder.

Jitters: Rest your soldering wrist on a jam jar. You'll be amazed how that helps control of the iron.

Mechanical joint to those fiddly cartridge connectors: Twist the wire firmly round the connectors using good tweezers. I use Ideal-Tek 00.SA. Expensive, yes, but so's your cartridge.

Hold everything rigid while soldering: A cocktail stick in modeller's vice works for the cartridge tags.

See? Easy. Alright, it isn't. It's a horrible job, but it can be made easier.

If I thought I could tape the twisted pairs to the inside of the arm tube using self-adhesive copper tape, I would. Pairs separated by 2mm. Wires rattling against a tube sounds like a recipe for microphony to me. I'd lightly tension the two twisted pairs to achieve their spacing, then use a poky thing to carry the self-adhesive copper tape down the tube without it sticking to everything, then transfer tape support to a jig at each end, then another poky thing with a cassette pinch roller to smooth the tape onto the inside of the tube. You would need a biggish arm tube, and the one I'm eying up is 16mm internal diameter (salvaged from a telescopic mop). It's even been anodised to look nice.

Finally, get rid of those horrible coaxial cables and phono plugs from arm base to pre-amplifier. Twisted pair all the way has equal resistances so induced interference currents develop equal voltages that cancel at the pre-amplifier input (even if it's not a balanced input).

Oh, and although it seems sensible to use arm wires all the way to the pre-amplifier input it increases loop resistance and that increases noise. If you don't want to make your own cable from scratch, use microphone cable. You could even buy a pair of XLR-XLR microphone cables and chop the female XLRs off. Keep those cables as short as you can tolerate because you need to minimise capacitance. You can always add capacitance later if necessary.

As pointed out in the previous post, the ideal place for the RIAA stage's input stage is directly under the arm base - that allows you to get cartridge loading capacitance down to about 20pF. Audio Technica MM cartridges work best with 100pF and that's hard to do with a remote RIAA stage.
Daniel Quinn
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#21 Re: Internal Tonearm wire recommendations

Post by Daniel Quinn »

A very interesting post.

If I must criticise and I must, you have given an awful lot of opinion the status of fact .
Morgan Jones
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#22 Re: Internal Tonearm wire recommendations

Post by Morgan Jones »

Daniel Quinn wrote: Tue Aug 01, 2023 12:31 pm If I must criticise and I must, you have given an awful lot of opinion the status of fact .
I believe all my statements were backed up by facts, but I'm happy to be corrected.
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Nick
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#23 Re: Internal Tonearm wire recommendations

Post by Nick »

Morgan Jones wrote: Tue Aug 01, 2023 2:06 pm
Daniel Quinn wrote: Tue Aug 01, 2023 12:31 pm If I must criticise and I must, you have given an awful lot of opinion the status of fact .
I believe all my statements were backed up by facts, but I'm happy to be corrected.
Well, just to be a pedant...
As pointed out in the previous post, the ideal place for the RIAA stage's input stage is directly under the arm base - that allows you to get cartridge loading capacitance down to about 20pF. Audio Technica MM cartridges work best with 100pF and that's hard to do with a remote RIAA stage.
The assertion that "the ideal place for the RIAA stage's input stage is directly under the arm base" is only conditionally true depending on how you weight the things that that location provide. If you regard getting loading capacitance down to about 20pF as important, then it has some merit. There may be other things that locating it elsewhere may optimize, and you may be using a MC where loading capacitance is less important, so it is also conditionally not true. As such, I would say calling it a fact may be false.
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Morgan Jones
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#24 Re: Internal Tonearm wire recommendations

Post by Morgan Jones »

That certainly is being pedantic, but I take your point. Yes, if you use MC then putting the input stage further away can reduce hum from the motor, but you need twisted pair and (ideally) a transformer-balanced input to avoid substituting cable hum.
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#25 Re: Internal Tonearm wire recommendations

Post by Daniel Quinn »

I counted at least 7 .

Your inability to recognise them , ( even when one was kindly highlighted by nick ) means I have no desire to argue with you . Sorry .
Morgan Jones
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#26 Re: Internal Tonearm wire recommendations

Post by Morgan Jones »

I'm afraid that if you claim I've made seven errors but fail to specify them, thereby denying the right to respond, then that's discourteous because it makes the assumption that all your bones of contention are correct. And they may not be.
Daniel Quinn
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#27 Re: Internal Tonearm wire recommendations

Post by Daniel Quinn »

You really are loose with your words. Another reason I won't argue with you.

For the record I didn't say errors , I said you conflate opinion with fact.
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Nick
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#28 Re: Internal Tonearm wire recommendations

Post by Nick »

I can only see another one, in the last but one paragraph, again, it is true (need to minimize capacitance) if you are using MM, far less so MC.

I can see several electronic truths, without any obvious (to me) opinions. Cant think of any reason why one would want to increase hum or noise.
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#29 Re: Internal Tonearm wire recommendations

Post by Daniel Quinn »

The classification of the job as "horribly fiddly " is a value judgement not a fact .

Some people may find it ' therapeutically difficult'

That is the first paragraph .
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pre65
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#30 Re: Internal Tonearm wire recommendations

Post by pre65 »

Daniel Quinn wrote: Wed Aug 02, 2023 9:24 am The classification of the job as "horribly fiddly " is a value judgement not a fact .

Some people may find it ' therapeutically difficult'

That is the first paragraph .
In terms of finding fault with a members post this one is "scraping the barrel" Dennis.

Have you nothing else to occupy your mind ? :cry:
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