Vintage Quad 405-2 Amplifier Review and in depth Tour 

Glad to hear you are still in love with your 405. Yes, there is a real tendency, especially on internet forums, for folks to insist that all sorts of stuff needs to be replaced. Commonly people will say "replace all of the electrolytics" suggesting that if you don't your device will expire imminently. This is clearly nonsense. However, it is true that electrolytic capacitors have a limited life, and SOME will probably need to be replaced at some point. In my 405 that I rebuilt, all of the small brown electrolytics either had already failed or where well on the way. None of them tested OK. (I hope you saw my repair video) Fortunately these days we have cost effective capacitor testers. I use the Peak one. You can always test the capacitors, and if they test fine, leave them be.

It's the most reliable piece of electronics I've ever owned, I actually paid a technician to apply the 'Dada' revision to my Quad 33 pre amp, and replacing the capacitors (and other things) did wonders. But I'll probably wait for at least symptoms before spending on the 405. My own soldering skills are minimal, so I did enjoy watching your video!

You may well be right. I've got another one here I need to refurbish, and it has the nice looms one would expect.

Great!

See here: keith-snook.info/QUAD-405-2-Modification.html

@@audionautica6843 A really useful and interesting web page. Many thanks and greetings from Italy

Well spotted. My understanding is that with the 405 the limiters were optional but on the 405-2 they were incorporated into the amp boards.

You are correct. I bought my 405 in 1976 and converted to 405-2 when the conversion kit was available from Quad. Soon after buying the 405 I put the limiters in as I quickly blew a KEF B200 without them in. The 405-2 still works fine to date.

Thanks for that. I have another 405-2 that I need to do a refurb, and I noticed the boards are grounded differently.

Sure is!

I have no idea. I've never seen a 303. Google is your friend!

@@audionautica6843 i learnt the 404 is bland the 303 is sweet nice midrange

@@hamzatatta952 If I ever get a 303 I'll let you know if I agree...

@@audionautica6843 it doesn’t have much of a grunt the midrange is nice I am going to sell mine

@@hamzatatta952 i use 2 bi-amped nd theres more grunt than one ever needs plus i use duel mono psus which expands the sound amazing