quad 405-2

[goodsguys]

Hi. And thanks for taking the time to read this post.

Can anyone tell me where to purchase a high performance bridge rectifier for my quad 405-2 amplifier. At the moment i have replaced the power modules with 405-3's from net audio and purchased 10,000uf caps for the power supply (not fitted yet), replaced all wiring with silver plated ptfe, high quality phono outs and finally michele speaker posts.

Also are there any instructions for the dual mono power supply.
I did a google search and there are descriptions of caps but not how to wire them up, ie which wires go where, which terminals on the transformer are to be connected to which terminals on the bridge rectifier then the caps.

Many thanks in advance. John.

[Barry]

If you want to use dual power supplies in your 405-3, thereby converting it into a dual mono amplifier, you will need to find room for two more 10,000uF smoothing capacitors.

The bridge rectifier used will be one of 20A rating with 200 PIV. If you choose to use Schottky diodes, you will need to fit 0.1uF disc ceramic 'snubbing' capacitors across each diode. These are usually included as part of the power supply upgrade kits.

Regards

[northwest]

I would get myself over to Kieth Snook's site - http://www.keith-snook.info and have a look at some of the options there. Kieth was always very helpful to me when I monoblocked my two 405's
Lots of useful info.

[goodsguys]

Hi. Thanks for the reply.

I did try keith's site earlier but did not find the info i was looking for.

So will any rectifier do, with the smoothing capacitors some brands tend to be better than others.

I can see the rectifer has two connections on one side which should go the transformer, then the two on the other side should go to the capaitors. Only problem my 405-2 has a fifth wire which comes from the secondary set of windings, bypasses the rectifier and goes straight to the lower capacitor the one nearest the phono inputs and the speaker output connectors.

Many thanks. John.

[DSJR]

Have you tried Dada Electronics? LOADS of useful info on all the solid state Quad gear and a wide availability of parts at not stupid prices, as well as made up "High End" boards for the 303/405-2 etc..... Their blogspot also has years of posts on tweaking Quads soundly designed circuits for a modern age while staying true to the original concepts.

http://www.dadaelectronics.eu/shop/components/diodes

http://www.dadaelectronics.eu/shop/d...upply-4x10000f

http://quadrevisionspot.blogspot.co.uk/

[goodsguys]

Hi. Sorry to reawaken this thread from the dead.

I emailed net audio who i purchased the quad 405 amplifier boards from and they suggested wiring the powersupply to the chassis, here is the exact reply got no idea what it means. Can anyone please explain or expand. And what does ov mean.


" Simply connect the LH speaker return to the center (0V) part of the twin caps nearest the caps for that channel and same for the right channel. Connect the same center by an individual wire to the chassis. Think of it as an H with the tall sides of the H is one channel 0V and the same for the other. The center of the H is two separate wires to the chassis. The speaker return goes to the T junction part of the H for each channel.

Best Regards

David Pritchard

[synsei]

I'm guessing 0V means zero volts...

[goodsguys]

Hi.. Many thanks for the reply.

At the moment i have the original quad power supply capacitor configuration, with the two negative speaker terminal's cables running up from the binding posts and then connecting to the chassis by being pinned under the bridge rectifier.

The two cables then become one cable and it runs to the negative terminal of the uppermost capacitor, then to the positive terminal of the lower capacitor. So this a series capacitor arrangement.

So for the dual mono power supply, should i keep the two negative speaker cables connected to the chassis (rather than letting them become one cable) and run one to the first pair of capacitors, then run the second to the second pair of capacitors, copying quad's wiring arrangement for each as mentioned above.

Hope this make some kind of sense.

Many thanks. John.