Opinions on Quad 405 Upgrade Boards?

[DarrenHW]

After a lot of talking about it, it's time I turned my attention to modifying / replacing my Quad 405 boards. I have original 405 boards which I've serviced with the Dada kit and replaced the OP Amps to OPA604. Originally I planned on upgrading the existing boards myself but I don't have the time, knowledge or confidence to execute this to the level I'd like to achieve, so I'm looking at just buying upgraded boards.

As far as I can see there are three options, Net Audio MK-3, Dada v2 or send them off to Keith Snook. To my eyes the Net Audio MK-3 OPA627 boards look like the best option?

As well as the 405's I have a Nakamichi AVR-1, this really shows the 405's lacking in detail and grunt but I prefer the sound of the 405's and chose the 405's for listening to music regardless of their deficiencies. I want to get the most out of the 405's but I really don't want to lose the Quad sound. I'd be grateful for any opinions on these upgrades, specifically whether they still sound like 405 boards?

[Wakefield Turntables]

Good luck getting into contact with Keith Snook, he couldn't be arsed returning several messages I left him on his mobile. :rolleyes:

[DarrenHW]

That's why he's last on the list of options!! How are you getting on with your 405?

[Light Dependant Resistor]

Hi Darren
I have a net audio mk3 board Quad 405 with opa627, it is a very capable amplifier.
and I would have no hesitation in recommending it.

Cheers / Chris

[DarrenHW]

Hi Chris,
Thanks for your input, did you buy it this way or upgrade? If upgraded do the Net Audio boards still retain the Quad character?
Cheers,

[Wakefield Turntables]

That's why he's last on the list of options!! How are you getting on with your 405?

Errrrr.... sitting on my window sill :o. I've had a new upgrade to the paradise phonostage to listen to and I've some new Little Bear kit comig over from China. The 405 will be used in a sort of fun 3rd mash up system that I'm messing around with.

[DarrenHW]

Lol. So much equipment, so little time...

[Light Dependant Resistor]

Hi Chris,
Thanks for your input, did you buy it this way or upgrade? If upgraded do the Net Audio boards still retain the Quad character?
Cheers,

Hi Darren
I upgraded existing 405 boards, and have used 405's standard for many years
yes the 405 character for very low distortion is retained but capability of
sound reproduction is much better with Net Audio mk3 boards. .

If you have studied 405 schematics, the bridge components define greatly what the amplifier does,
Over the years there have been many different implementations of the 405 design, but IMO the
Net audio implementation is one of the very best.

The Net audio boards tidy up all the areas that had shortcomings, like zener supplies for the op amps
used originally, are in the net audio mk3 boards transistor assisted. The Net audio boards still use
an inverting op amp configuration, so do not depart too much from Quads original design intentions.

If you can try also to hear a standard 303, a 405 net audio mk 3 is a bit better, but not by too much

Cheers / Chris

[r100]

hi, maybe a lead for some upgrades ... I upgraded a 306 with a kit from this vendor and was extremely happy with the sound after the upgrade ;-)

http://www.dadaelectronics.eu/shop/quad-upgrade-kits/quad-405-upgrade-and-revision-kit

http://www.dadaelectronics.eu/shop/dada-high-end-boards

greetings
ru

[DarrenHW]

Very informative post, thanks Chris :thumbsup:



If you can try also to hear a standard 303, a 405 net audio mk 3 is a bit better, but not by too much


Hmm, it would seem lots of people agree with you, maybe I should try a 303 first....

[mikmas]

Very informative post, thanks Chris :thumbsup:



Hmm, it would seem lots of people agree with you, maybe I should try a 303 first....

.. just to muddy it up, I have a recapped 303 (Dada) and a stock 405-2 ... have to say I prefer the 405-2 by a reasonable margin ;)

[DarrenHW]

A bit of research suggests maybe the 405 would be a better pairing with my Ditton 44's (4ohm) in my large-ish (25m2) room.

[DSJR]

I had two freshly updated (using Quad issue 7 mk2 boards) and new supply caps again supplied by Quad) 405-2's. Both suffered a high treble 'sparkle' for some hours after switch-on, which eventually disappeared. A properly sorted (not by Net Audio) 303 doesn't exhibit this at all and sounds fine right from switch-on...

I've read countless articles in the Dada BlogSpot and respect the banter back and forth during the development of their updates and boards. Their boards look to be faithful to the original designs, but with modern high quality components (all very well swapping out the op-amps for the latest fashion-chip, but what if it makes things unstable?). I've used Dada kits here and find the prices reasonable - so there!

By the way, Quad themselves, via their service dept. were still offering 405-2 boards for sale not very long ago (now on issue 10 I believe). Up to you, but please don't ever assume Quad didn't know what the hell they were doing. They may have worn blinkers for a while, but those days were long ago and the 606 didn't need to apologise for anything, as well as being able to properly drive a 4 ohm load, which wasn't necessary in the 303's day (or the mid 70's 405 era either I remember).

[DarrenHW]

Thanks Dave,

I've read countless articles in the Dada BlogSpot and respect the banter back and forth during the development of their updates and boards. Their boards look to be faithful to the original designs, but with modern high quality components (all very well swapping out the op-amps for the latest fashion-chip, but what if it makes things unstable?). I've used Dada kits here and find the prices reasonable - so there!
This is exactly the sort of input I was asking for :)

but please don't ever assume Quad didn't know what the hell they were doing.
Not at all, I'm not being pedantic but please see my OP:

As well as the 405's I have a Nakamichi AVR-1, this really shows the 405's lacking in detail and grunt but I prefer the sound of the 405's and chose the 405's for listening to music regardless of their deficiencies. I want to get the most out of the 405's but I really don't want to lose the Quad sound. I'd be grateful for any opinions on these upgrades, specifically whether they still sound like 405 boards?


I had two freshly updated (using Quad issue 7 mk2 boards) and new supply caps again supplied by Quad) 405-2's. Both suffered a high treble 'sparkle' for some hours after switch-on, which eventually disappeared. A properly sorted (not by Net Audio) 303 doesn't exhibit this at all and sounds fine right from switch-on...

By the way, Quad themselves, via their service dept. were still offering 405-2 boards for sale not very long ago (now on issue 10 I believe). Up to you, but please don't ever assume Quad didn't know what the hell they were doing. They may have worn blinkers for a while, but those days were long ago and the 606 didn't need to apologise for anything, as well as being able to properly drive a 4 ohm load, which wasn't necessary in the 303's day (or the mid 70's 405 era either I remember).

A question I didn't think to ask in my OP, was whether I should investigate other avenues before committing to the 405's. As there have been suggestions in this tread for alternative amps I think I need to work my way through the family first.

[worrasf]

I have a 33/303 that was fully upgraded by NetAudio even including a new PSU for the 33 and the 303 going to 303 SE level and I am totally satisfied with it. Improved clarity, detail and dynamics while somehow managing to retain the "Quad sound" (sort of just getting on with the music and not being in your face)
Steve

[Desmo]

I have a pair of fully upgraded Net Audio Quad 303's and also a pair of Quad 306's upgraded to Dada Electronics spec. (I like to bi- amp). In both cases the upgrades were significant, but did not destroy the fundamental "Quad sound". My current preference is for the pair of 306's - they just seem to have a bit more air about them, and perhaps a little more sparkle? But I could happily live with either. Indeed the 306's are in my main system as I type, and one of the 303's is in my second system in the bedroom. So they are always in use.

[DarrenHW]

Thanks guys, good to read you feel the Net Audio mods retain the character of the amps. Quad 306 added to audition list, I like the idea that they have "more air about them".

[Idlewithnodrive]

Bit late to the party (for a change :) ) but I much prefer my 405-2 to the 306. In fact, I recently bought (and then sold) another 306, just to make sure.

The 306 is a fine amp, still with the Quad house sound, but it's overtly bouncy (mids forward ?) nature seems to rob it of the ultimate overall unfussed smoothness of the 405-2. Just my 2p worth.