Internal wiring

[ceebmoj]

Internal wiring

I have built up a peter danuals chip amp kit and now have my enclosures finished. What type of wire should I be using for the internal wiring I see people often make up twisted pair form I assume single strand cable. I have also seen some people using what appears to be 2 core shielded cable. So what should I be using? Can I use the same cable for signal to amp as amp to speaker posts.

[AndrewT]

Hi,
I would not use the same cable for line level inputs as for speaker outputs.
Some swear by low area solid strand speaker wires but, I'm not one of them.
A twisted pair of 0.5mm or 0.6mm diameter copper wire is OK for line level.
These can be plain copper, or super refined, or one crystal. They can also be tinned (solder dipped), or tin plated or silver plated. They can be insulated with enamel, or plastic in it's various forms.

In general the internal wiring should be arranged to minimise radiated fields and this then reduces the tendency for interference in the low level stages (PCB and cabling).

[ceebmoj]

Originally posted by AndrewT

In general the internal wiring should be arranged to minimise radiated fields and this then reduces the tendency for interference in the low level stages (PCB and cabling).

thanks for the info however how would one go about doing the above?

also if you would not ues the same wire for signal to amp as amp to binding posts what to you ues hear? speaker wire? or a shealded cable?

blake

[BWRX]

Originally posted by ceebmoj
how would one go about doing the above?

Hi Blake. To minimize radiated fields you should twist the power and return lines (and signal and return) together. You should also try to keep the signal and power wires as far apart as possible. If the power and signal wires must cross, try to have them cross at 90 degree angles.

[jethdub]

Originally posted by BWRX


To minimize radiated fields you should twist the power and return lines (and signal and return) together.

In a larger project where there are a number of modules on their own pcbs what would be the best approach? Taking each pcbs signal return (ground/common) back to star ground individually means that it's not possible to twist signal and return between boards, there would just be a single signal wire. The alternative is daisy chaining the return from board to board throughout the system twisted along with the signal, creating one long return path...but I'd thought this approach was not so recommendable as seperate return paths for each module.

[troystg]

All wire should be twisted pairs unless you have a hardened enclosure (which most people don't).

Simple solution is a single twisted pair of solid core Cat 5 cable for signal wire, and 3-4 strands (twisted together then twisted with the "other" bundle) of the same cat 5 cable for each speaker lead.

The more complex solution is 22 ga. Silver plated Teflon insulated coax or twisted pair for signal wire and 16 - 14 ga. stranded Silver plated Teflon insulated wire for the outputs.


I get my Cat 5 from work ( ) and I get my Silver plated Teflon insulated from Steve @ Apex.jr.


Good luck on which ever you choose, but most importantly just enjoy the build and the listening!!!

[ceebmoj]

Hi all,

I have been looking at some wire and have selected a link to some cable that I can buy locally however I can’t find any solid core wire for the signal to amp, Having said that I assume that the phonon cables that I use to connect components together are strand cable so will a 15cm max run of stranded cable matter.

http://www.maplin.co.uk/module.aspx?...o=132&doy=22m1

I was thinking of using the above cable for signal to amp with the
screen connected to the case and the cores caring the signal or do you ling the return and shield together at the input end?

Could I also use the above cable for amp to speaker binding posts as the screen would screen the out put signal from any thing else in the amp box. Or would speaker wire be better between the amp and binding posts on the amp case as that’s what is going to carry the signal the rest of the way to the speaker and I don’t thing I have ever seen screened speaker cable.
I guess my problem is I just don’t know what will make a difference to the sound of the amp.

[lanchile07]

Well, in my third LM3875 integrated amp,I used this wire and it is great!
http://www.partsexpress.com/pe/showd...number=100-225

[dave_gerecke]

Whether the individual conductors are stranded or solid for the in cables shouldn't make a major difference (the cable mavens will disagree). If you are using the cable you showed from Maplin, are you going to use two runs of this, one for each channel, in a balanced configuration from the inputs to the amp module. Or are you planning on using this wire to run both left and right channels to the amp boards. Either way, you will want to ground the shield to the chassis.
I would recommend using speaker wire or perhaps cutting up a power cord for something to provide the necessary wires between the amp board and the speaker terminals. Shielded speaker wires aren't likely to be necessary, but if you use two separate conductors for the speakers, instead of two wires in a single jacket, you have the advantage of being able to twist the wires around each other. This provides electro-magnetic coupling between the wires that helps cancel out inteference.
You can also buy microphone cable that has the two conductors as a twisted pair, this will further help the input reject noise and interference.

Good luck,

Dave