Distance Transformer > Rectifier

[Magsy]

I'm building up a Peter Daniels dual mono 3875 kit and have a quick question regarding the distance allowable, or ideal, between the rectifier and the transformer.

As always when building these things I've picked an enclosure slightly too small. This leads me to consider mounting the two toroids in a seperate case with the rectifiers and amps in another. They would sit alongside each other or stack, length of cable would be 5" give or take.

Does this pose any problem running the AC out and back in?

[pinkmouse]

That should be fine, just make sure you twist or braid the wires well.

[safetyman]

Would distance make a difference between the the rectifers and the input of the board? I thought that it would not affect the power section as much as it would the input signal? ie. input being a small signal. Please correct me if I am wrong. Thanks.

[MRupp]

Does this pose any problem running the AC out and back in?

Separating transformers and rectifiers is not such a good idea. The rectifiers and transformer together create switching noise which will also be radiated through the wires between them, so ideally you keep those leads short (and twisted).

My 2 cents ....

[Magsy]

Thanks, the possible noise is what worried me.

I've pretty much decided to bite the bullet and buy another chassis like the first ($70!) so I can build two genuine monoblocks, one complete unit in each chassis.

The plan was to put the transformers in an ugly cheap box, but there is no good place to hide in an AV rack, so I'll take the expensive option based on the looks!

[Peter Daniel]

Most of my amps use separate PS box and there I place the rectifiers board as well. The umbilical cord carries DC voltage only and the length is usually 2 ft.

If it's a stereo amp with one PS, there is only one rectifiers board used (common to both channels).

[waltona]

I built my Brian 3875 kit with separate boxes for the amp boards and power supply. In the power supply box i had the transformer and the rectifier board and a plaited umbilical (about 60cm) to carry the DC to the amp box. I have zero hum or RFI apart from when messages arrive on my mobile.

By the way I used Brians ground scheme rather than Carlos's and I have zero hum.

Al

[Stabist]

Originally posted by waltona
I have zero hum or RFI apart from when messages arrive on my mobile.

Funny - this is somthing I have when using my LM3886 based GC (other 2 GCs with OPA541 and LM1875 are imune to that), and what I had with my ex amplifier (unison research simply 2) ... And oalways just in right channel?!?!?

[jimbo1968]

Originally posted by Magsy
I've pretty much decided to bite the bullet and buy another chassis like the first ($70!) so I can build two genuine monoblocks, one complete unit in each chassis.

What chassis are you using ?

[Magsy]

This one :
http://www.mapower.com.tw/mapower/Im...KC51-600-A.jpg

Unfortunately I cannot find anywhere in the EU selling it with the optional metal grill for the front.

I'm almost done on the first, so I'll show you the finished item tomorrow. I've made a mesh front plate and a new rear too. The chip mounts up nice against the inside on the big heatsink.

You can find it on ebay from Germany, Maplin have them at 40 quid each :/