Quad 405 Dual Mono PSU

[Bilko]

Hi everyone, great forum with tons of very useful stuff. I've lurked here for a while and finally jumped in!

I'm a relative noob to the Audio world but have dabbled in electronics for a while. I've acquired a Quad 405-1 and a 44 which I'm hoping to sort out and use as my main system. They've not been used for years and having read up on all the mods I've decided to start with the PSU.

I'm going to use a dual mono arrangement and have decided (to save my limited cash) to build my own. Having looked carefully at all the ones available from the likes of DADA and NetAudio I've designed my own circuit board and acquired 4 off 10,000uF 63V BHC Slit Foil Caps, two 8A 400V SIL Bridge Rectifiers and 4 off 100nf caps to bridge each of the main filter caps. I believe these are used for suppresion of spikes and transients?

I've noticed that these smaller caps are fitted to some DMPS boards but not others.

Are they needed and is the value of 100nf about right? (The ones I have are X2 rated 275v ones)

Also the original Bridge was rated at 35A and 400v, Will my dual 8A 400V bridges handle the power-on surge etc.?

(I'm retaining the 405 mains transformer and I'm also fitting 470nf caps across the AC out from the secondary of the transformer to the Center Taps).

I was just going to press on with this but there's so much experience and knowledge on this forum I thought it wise to ask for advice.

Thanks!

Bilko

[Bilko]

Just put this circuit together to show what I'm driving at,

Hope it helps.

Any comments and suggestions very welcome.

Thanks

[Bilko]

Sorry Mods, File size was too big for the attachment

Second attampt ...

Just put this circuit together to show what I'm driving at,

Hope it helps.

Any comments and suggestions very welcome.

Thanks

[Tyron]

Hi Bilko,

I wonder if you completed your PSU mod and how you got on? Have you done any other mods? I have a 405-2 and am considering doing similar.

Regards,

Tyron

[Zen Mod]

some useful pics

Quad 405 for beatgoeson - DIY Audio Forum

use google translator , if needed - from Serbian to English

[eyoung]

Hola, ZEN Maestro,

[#10171] You do not have permission to view this attachment.

I had trouble viewing your attachment...

Regards, Elwood

[Zen Mod]

sorry - I forgot that ; you must be logged to see them
I'll try to transfer these pics here today

[Bilko]

Originally Posted by Tyron

Hi Bilko,

I wonder if you completed your PSU mod and how you got on? Have you done any other mods? I have a 405-2 and am considering doing similar.

Regards,

Tyron

Hi Tyron,

It's been a while since I finished this project but I'm pleased to report a real success! The 405 is currently in use and I love it!

I made up a Dual Mono PSU circuit board and built the power supply using four BHC 10,000uf caps and modded the boards with most of the mods from mssrs. Ludwig and Snook. I'm over the moon with the results, the finished amp is far better than I had hoped for!

I've attached some pics.

Regards
Colin