Quad 405 - upgrade mods - opinions

[Whoops]

Hi,
I would like to improve the circuitry of my Quad 405 amplifier.

There's a lot of mods around the web, but most seem to come down to info from keith Snook website.
A full mod for the amplifier boards is described in this schematic, circuit diagram DCD MOD-3:

http://www.keith-snook.info/amplifier-hifi-schematics/QUAD%20405%20schematic%20evolution.pdf

There are pcb's available for the Quad 405 on ebay, there were also full boards from Net Audio (no longer available),
and there's also DADA electronics "High End" Boards based on Keith Snook DCD MOD-3 plus some addictions.

https://dadaelectronics.worldsecuresystems.com/shop/dada-high-end-boards/quad-405-high-end-replacement-board-with-opa604

I would like if anyone around here improved or modified a Quad 405 amp or have intentions of doing so?

Does anyone have experience in using the 405 with the boards from Dada?

thanks

 

[gridcurrent]

I would like to improve the circuitry of my Quad 405 amplifier.
There's a lot of mods around the web, but most seem to come down to info from keith Snook website.

what is his problem with the 405 being inverting ?

I would like if anyone around here improved or modified a Quad 405 amp or have intentions of doing so?

intentions:  yes. 
LM318 input amplifier,  less complex output with complementary pair (emitter followers).


[/quote]

 

[Whoops]

what is his problem with the 405 being inverting ?

Keith Snook explains the reasons quite well in his website, it's a good read:

http://www.keith-snook.info/quad-405-mods.html

 

[cyrano]

Does anyone have experience in using the 405 with the boards from Dada?

Used to have an occasional beer with the guy who runs DaDa Electronics. He knows his stuff and most customers are very pleased with the services they offer. They used to refoam speakers and repair amps and they still do. But that's a minor business compared to the Quad stuff.

For some strange reason, there's a number of Quad collectors here in Antwerp. The one I know owns about a dozen 303's and five 405's, not counting preamps, tuners and ESL speakers.

Those collectors changed the business and DaDa Electronics was born.

Antwerp used to have about a dozen of good repair shops. There's two left. The other one doesn't cater to consumers, but works for the likes of Sony.

I used to own a pair of 405's myself, when I was djing at uni. You know the setup: a pair of Lenco's, a Rodec mixer, some Bose 802's and some VOTT's. And, of course, some Faylon 100W tube amps for the VOTT's. Some of that stuff is gold for some audiophools, these days.

 

[Whoops]

Used to have an occasional beer with the guy who runs DaDa Electronics. He knows his stuff and most customers are very pleased with the services they offer. They used to refoam speakers and repair amps and they still do. But that's a minor business compared to the Quad stuff.

Thank you so much for the info.

I need an amp for my Proac Studio 100 speaker, I would like to buy a Bryston but it's too expensive for my possibilities.
I already own the Quad 405, it's free.

One channel has problems and needed to be reapaired, and it's also already time for a recap since it has already 40 years and it was never recapped, so it needs service anyway.
As I'm doing service on the prefer I prefer at least to take some of the common knowledge about these amps and improvements an apply them.

I just havent decided yet if I will modify my existing boards or the buy new boards from Dada