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mains leads...

K

Ken C

pfm Member
hi guys,

what makes a good mains (IEC) lead? low resistance? (in which case i expect to see thick mains cables, rather than the lead size ones i see around). low overall impedance?? (low L and high C?) -or does this depend on what equipment is being powered?

you guys who have made your own leads, what were you looking to achieve and how did you come up with these objectives?

many thanks and enjoy


ken
 
Being quite pragmatic about this, I normally use the same gauge and material that is used between the sockets beneath the plaster; I guess this would be 2.5 mm2 solid core copper.
Phonosophie make a quite similar mains cable with high quality plugs.
My HiCap sounds better with such an unshielded cable than otherwise. YMMV ;)

Best regards,

Oliver
 
anyone ever tried 2.5mm sq mains T&E cable (or even 6mm sq) for the mains cable from the socket to IEC for hifi equipment. after all this cable carries mains a typically longer distance from the consumer unit to the socket -- i dont see why it should becomes suddenly unsuitable for this last leg. of course, one could always dispence with the socket and take the cable(s) straight to IEC and then equipment -- but of course, this is NOT safe. any comments?

enjoy

ken
 
Originally posted by prowla
I'm currently using a hydra I made with 4mm cable "rescued" from a computer installation.
Click to expand...


could you please also comment on any improvements you got out of using this kind of cable -- i assume you were using the "usual" IEC mains cables supplied with the kit before your home made hydra.

many thanks prowla...


enjoy

ken
 
you guys who have made your own leads, what were you looking to achieve and how did you come up with these objectives?
Click to expand...

1) I actually needed a new power lead for a new box.
2) Making my own lead gave me something to do one dark , drizzly , night.
3) I could mix and match the components used and also make it to a custom length if needed.
4) I looked at other designs that I'd seen, owned or used and decided to borrow some ideas and features of others to make my own.
5) I'd spent good money on other aftermarket leads and decided that i couldn't honestly say I'd noticed a vast ( or any) sonic improvement over stock oem leads and so was determined to keep more of my hard earned in my wallet where it belongs.
6) In direct comparison with 'bought' leads that i own , i reckon my DIY 'posh power cords' a can hold their own. They are good enough for my needs and are what i will be using for the forseable. I'm not saying others will like them, I'm not even claiming that they will even make one single iota of sonic difference to Electrical components that they power. What i will say is that they are easy and cheap to make and try. if you don't like them then, so what it's only a few quid. I'm sure we've all wasted money on things that really don't work in the past?
Hope this helps.

Sids DIY 'Posh Power Cord'
 
could you please also comment on any improvements you got out of using this kind of cable -- i assume you were using the "usual" IEC mains cables supplied with the kit before your home made hydra.
Click to expand...
It is kind of difficult, since I got there by a roundabout route...
I started off running things off a cheap plugboard.
I was a bit dissatisfied with my bass and thought the sound was a bit harsh, so I decided to make up a plugboard. Sounded better but not quite there.
Then I got a mailshot from Russ Andrews and bought a couple of Yello leads. They seemed to smooth things out but maybe lost a bit of pace.
Then I made up some cables (MK plugs, 4mm cable, Schurter or Wattgate IEC plugs). They brought back a little life, but were perhaps a bit hard edged. I had a few attempts at this.
Then I made up another plugboard out of MK unswitched sockets and 4mm wire. I expected great things, but it was crap! I lost all the top end. (The system sounded very "comfortable" at low volume though...)
So I decided to carry on tinkering and make a Hydra.
It's got an MK tough plug, 4mm core wire into a grey plastic junction box, 6 wires out - 3 to Wattgate IECs, 1 to Marinco (same really), and two with cheaper IECs unused as yet.
When I switched over I knew I'd got it!
The sound opened up completely. Tuneful bass, separation of instruments, rhythm, basically playing music!
At some point I need to go back to the original cables and have a listen again to do the comparison (not into the crap plugboard though).
 
sid and coke:

...6) In direct comparison with 'bought' leads that i own , i reckon my DIY 'posh power cords' a can hold their own...
Click to expand...

i have looked at your web site and found it very interesting!
did you find that your braided cables did reject RFI more than perhaps what you had started with? what was the sound quality like -- especially with the lower RFI ??

many thanks --- exactly the sort of info i was after ...

enjoy

ken
 
prowla:

So I decided to carry on tinkering and make a Hydra.
It's got an MK tough plug, 4mm core wire into a grey plastic junction box, 6 wires out - 3 to Wattgate IECs, 1 to Marinco (same really), and two with cheaper IECs unused as yet.
When I switched over I knew I'd got it! The sound opened up completely. Tuneful bass, separation of instruments, rhythm, basically playing music!


good for you ...!! i assume the 4mm core wire is the "round" type -- a bit basic i'm afraid. i think i have the sort of junction box you are talking about -- mine is 8-out and its called something like "ElekTek". i want to make up my own hydra as the grahams one i have now hasnt got enough IEC outlets -- and i need something i can dismantle relatively easily. most importantly, i want something that SOUNDS better.
At some point I need to go back to the original cables and have a listen again to do the comparison (not into the crap plugboard though).

i am sure this will simply confirm that you design worked for you.

in terms of design direction, i am starting from the generally accepted view that dedicated radial circuits with "thick" wires (i have my spur wired in 6 mm) are a good thing. accepting that, it would seem to me that if it was practical to extend this 6mm cable (in fact more than 1) to the IEC plug into equipment -- we would reap benefits as we would lose the mains plug interface -- with all the joints. but we know this is unsafe -- so next best thing -- have a mains socket, but still use the same mains cable to delivery power from the mains plug to the IEC. well, 6mm probably wont fit into standard IEC but you get my drift. no impedance change. this SHOULD sound good -- but almost all reports of people who have tried mains wire for mains leads have been negative. confusing. which means there are OTHER more important issues than just low impedance, probably...

many thanks for response.

enjoy

ken
 
One concern I have is that the cables are obviously a bit stiffer and so could transmit vibrations. I think I'm OK though (did a bit of cable dressing).
My 4mm cable was "rescued" from a computer installation, the MK plug & junction box were from B&Q, and the Wattgate IECs were from Russ Andrews. (The Marinco IEC was from Audusa, but I'd probably replace it with another Wattgate sometime.)
The cable just fitted into the screw connections in the junction connector thingy. I didn't solder it (none of the other connections are soldered, so why that one?). Likewise the mains plug just accepted the cable (and sleeve for the clamp).
I wonder if going for thicker cable would cause problems in connecting/stiffness/fitting, etc?
I'm thinking of replacing the junction box (an unpretty grey plastic box) with a slimline metal case that could sit in my rack.
 
I think your going in the wrong direction concentraiting too much on the wires themselves.
It is connections that cause all the problems.You need to basically loose as many connections as possible and make sure that each connection is as tight and clean as possible.
Does'nt matter how "pure" a cable is if the connections are bad.
A lot of sound differences people hear between cable are actually connector difrences ,and often diffrences in tightness,and not specifically cable related problems.Certain shapes of wire and thickness will give better connections in different circumstances and is one of the reasons mains wire such as is found in you home makes poor mains leads , mains plugs and IEC sockets cant grip the thick solid core cable well,(and will onlt touch at the extreme top and bottom) while a multistrand cable will form a much tighter connection due to being able to be conpressed flat and having a much greater contact area..
 
Originally posted by spxy
I think your going in the wrong direction concentraiting too much on the wires themselves.
It is connections that cause all the problems.You need to basically loose as many connections as possible and make sure that each connection is as tight and clean as possible.
Does'nt matter how "pure" a cable is if the connections are bad.
A lot of sound differences people hear between cable are actually connector difrences ,and often diffrences in tightness,and not specifically cable related problems.Certain shapes of wire and thickness will give better connections in different circumstances and is one of the reasons mains wire such as is found in you home makes poor mains leads , mains plugs and IEC sockets cant grip the thick solid core cable well,(and will onlt touch at the extreme top and bottom) while a multistrand cable will form a much tighter connection due to being able to be conpressed flat and having a much greater contact area..
Click to expand...

very interesting. now we are getting concrete theories. and i can buy what you say. a poor connection will probably result in larger impedance (and perhaps some capacitive effects too?)

what are your thoughts on soldering? does this improve the quality of junctions? i wonder if my grahams hydra is soldered -- cant tell unless i dismantle it - am in no hurry to do this although i am 1 output short on my hydra (for 'geddon).

i will measure a few "connection" impedances and see what sort of numbers i get with different cable and plugs.

many thanks for interesting thoughts...

enjoy

ken
 
One of the things that many overlook is the materials used in the connectors.

Take a bunch of IEC mains leads (from your hi-fi or your PC for example) and peer into the sockets.

You will find many have brass terminals, but the people who know their stuff (e.g. Naim) will have copper terminals. You can tell the difference by the colour.

Now this is also a double-edged sword - copper is the better conductor, but is not as good for this style of socket as it's less springy and over time work-hardens more readily, but often by this time the contact has opened up and makes worse contact.

To overcome this the moulding around it has to be well designed to maintain contact pressure.

The cable though does make a difference and I don't care what anyone says, usually thicker is better (and lower impedance) for mains wires providing it doesn't then stress the connector or add microphonic effects.

It's all a balance, but look at those IEC's before you plug them in, then see how difficult it is to buy off-the-shelf leads with copper terminals - none of them quote the materials used !

Andy.
 
Originally posted by Ken C
anyone ever tried 2.5mm sq mains T&E cable (or even 6mm sq) for the mains cable from the socket to IEC for hifi equipment. ?

Yep. Made one up for use with my Micromega S3. It gave a small but worthwhile improvement, a bit sharper and faster, which is what that ol' girl needed.
Click to expand...
 
andy, many thanks...

Now this is also a double-edged sword - copper is the better conductor, but is not as good for this style of socket as it's less springy and over time work-hardens more readily, but often by this time the contact has opened up and makes worse contact.


presumably, this could be the reason why people report better performance with round hole sockets and plugs -- apparently they make a lot better contact.

i have always "believed" that using the same materials in the connections is a "good thing" -- my reasoning being any change of impedance across junctions may lead to small, but nasty impedance change effects -- not sure this is really true -- but i have no alternative theory.

presumably, soldering is perhaps a bad idea because, again, change of materials involved. OTOH, there is solder all over the place in the mains path of amplifiers, power supplies etc.. and i think naims speaker plugs are made of nickel (i am not sure, so stand corrected ...) and the speaker cable is presumably copper... one wonders why? and would it sound better if it was all copper? is this even possible?

enjoy

ken
 
rustyB, many thanks.

interesting that you found some performance gains in using mains T&E cable for mains lead.

enjoy

ken
 
i have always "believed" that using the same materials in the connections is a "good thing" -- my reasoning being any change of impedance across junctions may lead to small, but nasty impedance change effects -- not sure this is really true -- but i have no alternative theory.
Click to expand...

There are well known thermoelectric effects in the junctions between dissimilar metals.

In fact the whole area of thermocouple thermometry is based in this - connect two metals of different types together and they will exhibit a potential difference that varies with temperature and is non-linear. Whilst we are only talking about microvolt signal levels here (for example a K type thermocouple is nominally 41-42 uV / deg C, IIRC) in low level signal paths this could be critical.

Dissimilar metals can also increase corrosion rates dramatically, most radio amateurs will tell you that making an antenna from a combination of aluminium and brass, for example, is a total recipe for disaster, they are two of the worst materials you can bring into contact with each other and will bring about dramatically accelerated corrosion rates.

Even Lead / Tin soft solders and copper / brass have slight risk of accelerated corrosion, in humid / moist atmospheres.

As with everything there's a balance to be drawn when one gets to the practicalities of real world implementations.

Andy.
 
Hi Andy,

Nice to hear from you again, on the subject of solder which I note you have mentioned here, what is your recommendation when soldering inside 'our highly prized' equipment ??

I must admit I normally just buy the 'stock' stuff from RS or Maplin, but I often wonder if this is the best option.

Bye the way, you've got mail.....

Cheers
Mike
;)
 
Hi Mike,

Saw your email, will reply later on...

For solder I've always used eutectic solder intended for SMD work in a Tin / Lead / Silver mix.

It gives very nice looking joints, with good wetting abilities and a low melting point, which is perfect for low power stuff.

I'm also experiementing with lead-free solder at present, in a Tin / high silver content / copper mix. This brings difficulties though, as the joints don't look nice in the same way we're used to (even though they may be fine) and the melting point is a lot higher. There is also the issue of compatibility with the PCB and lead materials.

There's a significant additional cost to making my reg PCB's compatible with lead-free solder and subsequent shelf-life / storage problems.

It's something industry needs to get its head around as the use of lead in solder will be banned in a few years and UK industry is dragging its heels as usual. The significant amount of education and 'un-learning' required in terms of what makes a good solder joint means that we should be starting to analyse this now.

DTI primary WEEE / ROHS website:

http://www.dti.gov.uk/sustainability/weee/index.htm

National Physical Laboratory website, lead-free information:

http://www.npl.co.uk/ei/news/pbfree.html

Andy.
 
last friday, i had a go at making my own hydra. up to now, i had been using grahams hydra that was made some time ago. i needed one more output and also, i needed the whole thing to be slightly longer.

i was quite curious to find out what was inside the grahams hydra so, instead of just cutting the cables either side of the Raychem thermoform, i actually stuggled to cut it open (after warming it up a bit) and have a look at the hydra joints. these were soldered -- reasonably well -- the joints were string enough, and very well insulated so there was no change of bare L/E/N touching each other. also, the whole joint area was very strong, with the thermoform gripping the whole thing very tightly, with the added security of grands to stop any pulling action affecting the thinner wires of the inner core.

having more or less desctoyed the thermofoam while dismantling it -- my new hydra was going to be a rather less robust affair, but still hopefull well jointed. i wish i had a camera to record the whole project -- well, next time.

for the portion of the cable that carries the mains plug, i used 1.5m of tower's 2.5mm^2 3 core rubber flex, rated 25 amps/6000 watts. for the IEC portions, i used std naim leads. i measured rubber flex's resistance to be about 0.2 ohms/m, compared to std naim cable which i measured to be about 0.4 ohms/m (can someone confirm? my multimeter is not that good).

its no more difficult to fix the 2.5mm^2 cable into 13 amp plug and i managed to make what i believe are good, tight connections. i needed 7 outputs (2-250, 2xsupercap, 1xXPS, 1 prefix's hicap, 1 geddon) -- all about 60 cm, except for the hicap and geddon's IEC's which needed to be longer, about 1.2m or so.

i simply twisted all the corresponding bare bits (about 2 cm or so) of all the leads and supply core, and then secured each in a separate 20 amp rated connector so the bare bits were well insulated. then i further covered the connectors with insulating tape before covering the whole thing in a covered platiic box.

before connecting it up, i continuity tested L/E/N and all was OK. then i connected my new hydra to my hifi. no explosion !!!

but what about the sound. using DBT terminology, if ever there was a case of "expectation bias" -- there was plenty of it here. i WANTED the thing to sound a LOT better than my old grahams hydra.

IT DIDN'T.

the sound was edgy and had a glare. lacked interest. lacked "that which makes you want to play your hifi". but i really shouldnt have expected to immediately notice big improvements. my system was OFF when i was building this contraption -- for about 2 hours. so there was bound to be some warming up issues to get the system back from its nap.

its been 3 days now. the sound has improved a lot since friday. yesterday, i sensed that magic beginning to return, so perhaps it was a warmup issue after all.

however, i dont sense that this is going to be earth shattering improved mains supply to my system.

my next step is to solder the joints and see if this makes any difference. this time, i will make sure the supercaps and XPS are powered so that there are no serious warm up issues to worry about. if there is no joy, i will shorten the cables slightly (i may have been too generous with the lengths).

then as final change, i will remove the thick rubber flex and use standard naim cable for the bit of the hydra connected to mains. this should get me back to square one, but with more outputs and a slightly longer hydra so IEC connections are not stressed.

all in all, interesting experiment, especially if it turns out the thick rubber flex is the culprit in degrading the music.

i will let you know how my other experiments go... if there is interest.

enjoy

ken
 
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