I would like to make a series of affordable power cords for my amps and other gear.
Does anyone know of a good source for reasonably priced (shielded?) power cord and plugs. There is so much chatter around the relative benefits of high end power cable that it is hard to sort through all the noise.
Thanks
Does anyone know of a good source for reasonably priced (shielded?) power cord and plugs. There is so much chatter around the relative benefits of high end power cable that it is hard to sort through all the noise.
Thanks
neil_kaye said:
No need to sort through the noise; just plug your ears.
I understand shielded interconnects, but shielded power cables make no sense at all to me. If you had 6ft long audio interconnects, would it make sense to shield only the last two inches of the cable? Of course not. It also makes no sense to shield the last couple of feet of wire extending from the wall socket.
I would say just make all your power cords out of the same stuff in the wall, but it isn't very flexible.
Re: Re: DIY Power cable
Man I hate that "miles and miles" argument..
Ground loop current flowing on a shield does not create an internal magnetic field.
Ground loop current flowing on an individual conductor does. (note: that is where the 15 nH per foot number comes from...a shield does not have that)
Run a full differential input with a REAL amplifier design that rejects (or otherwise bypasses) input ground current, and one that doesn't consider the wall outlet ground as a reference.. and I'll agree with your premise.
Otherwise, you are incorrect.
Cheers, John
theAnonymous1 said:
Man I hate that "miles and miles" argument..
Ground loop current flowing on a shield does not create an internal magnetic field.
Ground loop current flowing on an individual conductor does. (note: that is where the 15 nH per foot number comes from...a shield does not have that)
Run a full differential input with a REAL amplifier design that rejects (or otherwise bypasses) input ground current, and one that doesn't consider the wall outlet ground as a reference.. and I'll agree with your premise.
Otherwise, you are incorrect.
Cheers, John
Attachments
a question or two for poster #1
why do you want to make your own? Is there something inherently wrong with the existing cables? If so, what, and how have you tested or defined the problem?
Or have you just spent all you can already on oxygen-free (or enhanced...) solid silver (or gold, or any other precious metal) interconnects, and pyrimidic stands of mystical proportions to keep it all off the floor and hence away from stray induced currents and capacitance effects inherent in nylon/wool carpet or solid wood floors? Hmmn? Got the tin-foil hat too? :-\
Or are you just a born tinkerer who is keen to make some cool looking cables you can call your own?
why do you want to make your own? Is there something inherently wrong with the existing cables? If so, what, and how have you tested or defined the problem?
Or have you just spent all you can already on oxygen-free (or enhanced...) solid silver (or gold, or any other precious metal) interconnects, and pyrimidic stands of mystical proportions to keep it all off the floor and hence away from stray induced currents and capacitance effects inherent in nylon/wool carpet or solid wood floors? Hmmn? Got the tin-foil hat too? :-\
Or are you just a born tinkerer who is keen to make some cool looking cables you can call your own?
I`m using the 3x2,5kv (mm) EKKJ from this Swedish company; shielded solid core copper in black rubber makes a superb powercable.
Btw; the thickest ones in 6 and 10 kvmm solid makes the absolute ultimate low-end speakercables. Same for tops, but mybe not 10kvmm. Needs an hour of high-level burn-in!
https://www1.elfa.se/elfa~eu_en/catalog/itemPage.do?isQuery=yes
https://www1.elfa.se/elfa~no_no/index.jsp?ignorecookie=true
Btw; the thickest ones in 6 and 10 kvmm solid makes the absolute ultimate low-end speakercables. Same for tops, but mybe not 10kvmm. Needs an hour of high-level burn-in!
https://www1.elfa.se/elfa~eu_en/catalog/itemPage.do?isQuery=yes
https://www1.elfa.se/elfa~no_no/index.jsp?ignorecookie=true
Re: Re: Re: DIY Power cable
If the amp has a pin one problem, just fix it already!
I am perpetually amazed at the lengths some folks go to to band aid fundamentally flawed designs, that could often be fixed at less cost and inconvenience then the band aid implies.
Input stages: Do the pin one thing right, use common mode chokes and band limit the stage to avoid slew rate problems further into the system (Designing an audio amp with 10 MHz small signal bandwidth is normally a mistake IMHO, and doubly so if you go for non filtered DACs).
Bridge rectifiers: 220nF across each diode will reduce the tendency to phase modulate any RF carrier in the vicinity (And makes most of the differences between diodes go away).
Output stages: Common mode chokes to keep rf out of the feedback loops.
Connecting the internal reference to the chassis at one point is reasonable to control common mode voltages between bits of kit, but no signal current should flow in this connection.
My working assumption is that if routine external power effects have noticeable impact on my gear, there is a problem (and it ain't with the power cable).
Same thing for currents in the screen connections (easily tested) and for operating a cell phone next to the signal cables.
I get the feeling that a lot of the more self considered 'audiophile' designs go for 'as simple as possible and then some', and fail to engineer in robust handling of non ideal external behaviour.
Be conservative in what you generate and liberal in what you accept applies as much to audio gear as it does to data comms standards.
Incidentally, if anyone has some solid real world experience with the THAT corp balanced line receivers (with the rather clever bootstrap), particularly with regard to RF immunity, please share.
Regards, Dan.
jneutron said:
If the amp has a pin one problem, just fix it already!
I am perpetually amazed at the lengths some folks go to to band aid fundamentally flawed designs, that could often be fixed at less cost and inconvenience then the band aid implies.
Input stages: Do the pin one thing right, use common mode chokes and band limit the stage to avoid slew rate problems further into the system (Designing an audio amp with 10 MHz small signal bandwidth is normally a mistake IMHO, and doubly so if you go for non filtered DACs).
Bridge rectifiers: 220nF across each diode will reduce the tendency to phase modulate any RF carrier in the vicinity (And makes most of the differences between diodes go away).
Output stages: Common mode chokes to keep rf out of the feedback loops.
Connecting the internal reference to the chassis at one point is reasonable to control common mode voltages between bits of kit, but no signal current should flow in this connection.
My working assumption is that if routine external power effects have noticeable impact on my gear, there is a problem (and it ain't with the power cable).
Same thing for currents in the screen connections (easily tested) and for operating a cell phone next to the signal cables.
I get the feeling that a lot of the more self considered 'audiophile' designs go for 'as simple as possible and then some', and fail to engineer in robust handling of non ideal external behaviour.
Be conservative in what you generate and liberal in what you accept applies as much to audio gear as it does to data comms standards.
Incidentally, if anyone has some solid real world experience with the THAT corp balanced line receivers (with the rather clever bootstrap), particularly with regard to RF immunity, please share.
Regards, Dan.
Re: Re: Re: Re: DIY Power cable
Hey... I agree...
Unfortunately, there are far too many unbalanced input audio deeevices around. No pin one
Yup...I consider constantly changing line cords to be a bandaid. I point out some physical geometries which cause line cord (ground loop) dependence.. RF, I defer to guys like you.
Cheers, John
dmills said:
Hey... I agree...
Unfortunately, there are far too many unbalanced input audio deeevices around. No pin one
dmills said:
Yup...I consider constantly changing line cords to be a bandaid. I point out some physical geometries which cause line cord (ground loop) dependence.. RF, I defer to guys like you.
Agreed. Unfortunately, on this side of the pond we have the NEC which requires a bonded chassis to ground, and we end up with currents in places that are not really well controlled.dmills said:
Total agreement.dmills said:
Cheers, John
Hehe, this is the wrong forum to ask about power cables, there are lots of people on here who don't like things that don't affect harmonic distortion measurements.
Use something thick, braided (like Kimber or Yarbo speaker cable), no shield, solid plugs (Wattgate 320 & something like an MK Tough Plug for the wall end). In the UK we have a fuse in the power lead, which can be bypassed with a solid copper bar.
The RFI reduction and loop impedance can be measured but really, what's the point? Just listen & enjoy!
Simon
Use something thick, braided (like Kimber or Yarbo speaker cable), no shield, solid plugs (Wattgate 320 & something like an MK Tough Plug for the wall end). In the UK we have a fuse in the power lead, which can be bypassed with a solid copper bar.
The RFI reduction and loop impedance can be measured but really, what's the point? Just listen & enjoy!
Simon
Re: Re: Re: Re: Re: DIY Power cable
Unbalanced stuff is just a pain in the ****, but there are reasonable things you can do even there....
If you use a phono socket that is isolated, you can use a differential input stage between the pin and the (isolated) sleeve to at least minimise the pain on the input side, and it is possible to implement impedance balance at the output, which will at least get you some resistance to earth loops.
For a balanced IO device, the internal signal reference trace is strictly a local reference, it never leaves the case, and as long as it is bonded to the case at A SINGLE point, it really does not matter what voltage the box ends up at as long as it remains within the common mode range of the IO drivers. Shield currents have very little effect as long as the shield is terminated to the case and does not enter it (Tests indicate that SCIN is only a factor for a stupid amount of shield current or where the input stage CMRR is exceptional).
Currents flowing due to earth loops will flow on the outside of the case, but so what?
Loop currents are harmless unless they have some way to couple to something inside the box.
For some fascinating work on this (including some measurements) see www.tonywaldron.co.uk and his papers on interference free audio and on screen bonding.
Searching the 'theatre sound' mailing list for some very extensive discussion featuring Tony Waldron, Neil Muncy and Bill Whitlock on this subject may also be interesting.
Something of a straw man argument don't you think? I don't think anyone here has claimed a measurement as crude as THD can be used to completely qualify an audio component. For certain no engineer would.
However, as power input quality (within reason, and there is nothing a power lead can do about anything that would exceed 'within reason') should NOT effect the performance of an audio component, we can state with some certainty that any design where changing a power cord DOES effect the sound, must be a poor design at least in engineering design terms (it might meet some other criteria, say low parts cost or minimal components or something, but as an audio component of reliably good and consistent quality it fails).
That fuse is there for a reason, as without it that cable could pass 32A without causing anything to trip. This is horrible advice to give any newbies reading this thread, and is a blatant safety problem (not to say completely lacking in common sense).
There are a few very special cases where using an unfused plug is acceptable, but audio is never one of them (Think portable Xray machines where the maximum duty cycle is tiny and where other protective measures are in place).
Some of us would like to measure such effects so that we can design gear that does not need funky power cords just in order to work right. You cannot do that without measuring the basic cause of the problem and its effects as otherwise you are not doing audio engineering you are doing audio voodoo, and I am a poor witchdoctor at best.
Regards, Dan.
jneutron said:
Unbalanced stuff is just a pain in the ****, but there are reasonable things you can do even there....
If you use a phono socket that is isolated, you can use a differential input stage between the pin and the (isolated) sleeve to at least minimise the pain on the input side, and it is possible to implement impedance balance at the output, which will at least get you some resistance to earth loops.
We have CE which includes bonding requirements somewhat more rigorous then the NEC does (mostly because our domestic small power is 230V), but you miss the point:
For a balanced IO device, the internal signal reference trace is strictly a local reference, it never leaves the case, and as long as it is bonded to the case at A SINGLE point, it really does not matter what voltage the box ends up at as long as it remains within the common mode range of the IO drivers. Shield currents have very little effect as long as the shield is terminated to the case and does not enter it (Tests indicate that SCIN is only a factor for a stupid amount of shield current or where the input stage CMRR is exceptional).
Currents flowing due to earth loops will flow on the outside of the case, but so what?
Loop currents are harmless unless they have some way to couple to something inside the box.
For some fascinating work on this (including some measurements) see www.tonywaldron.co.uk and his papers on interference free audio and on screen bonding.
Searching the 'theatre sound' mailing list for some very extensive discussion featuring Tony Waldron, Neil Muncy and Bill Whitlock on this subject may also be interesting.
SimontY said:
Something of a straw man argument don't you think? I don't think anyone here has claimed a measurement as crude as THD can be used to completely qualify an audio component. For certain no engineer would.
However, as power input quality (within reason, and there is nothing a power lead can do about anything that would exceed 'within reason') should NOT effect the performance of an audio component, we can state with some certainty that any design where changing a power cord DOES effect the sound, must be a poor design at least in engineering design terms (it might meet some other criteria, say low parts cost or minimal components or something, but as an audio component of reliably good and consistent quality it fails).
Do NOT do this.
That fuse is there for a reason, as without it that cable could pass 32A without causing anything to trip. This is horrible advice to give any newbies reading this thread, and is a blatant safety problem (not to say completely lacking in common sense).
There are a few very special cases where using an unfused plug is acceptable, but audio is never one of them (Think portable Xray machines where the maximum duty cycle is tiny and where other protective measures are in place).
The RFI reduction and loop impedance can be measured but really, what's the point? Just listen & enjoy!
Some of us would like to measure such effects so that we can design gear that does not need funky power cords just in order to work right. You cannot do that without measuring the basic cause of the problem and its effects as otherwise you are not doing audio engineering you are doing audio voodoo, and I am a poor witchdoctor at best.
Regards, Dan.
Agreed 100%.
Obviously 3 conductor only applies to class 1 equipment, class 2 you can use 2 conductor provided the connector used cannot be used in class 1 equipment (To avoid the risk of accidentally using a two conductor cable to power class 1 gear).
Electrical safety, it trumps audio tweaking.
Regards, Dan.
Obviously 3 conductor only applies to class 1 equipment, class 2 you can use 2 conductor provided the connector used cannot be used in class 1 equipment (To avoid the risk of accidentally using a two conductor cable to power class 1 gear).
Electrical safety, it trumps audio tweaking.
Regards, Dan.
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