Anyone have a quad 405 based setup?

[bobchiba]

Hi, ive recently decided I want to try out some highly regarded 'vintage' sort of kit. I've always loved the design of the early quad gear, namely the 405 current dumper. What I have in mind would be to use my Rega deck with a modern phono stage like a CA540p maybe, and use a passive pre amp like the ones Creek do to feed it to the 405, the reason being I probably cant stretch to a quad pre and have the said kit readily available to me. Would the passive pre work with the quad, I know some pwr amps can work of a stepped line livel signal but im not overly sure. Also what kind of characteristics do these quad amps have im looking at as late as possible 405-2. I listen mostly to what would be described as rock/guitar based stuff i suppose.

 

[Anonymous]

Hi, I use a Quad 405 power amp although heavily modified to the Netaudio MK3 DMPSU spec.

You can indeed successfully use a passive pre like the Creek OBH-22 or the Icon Audio passive.

The input sensitivity on the 405 is quite high so you might benefit from using some attenuators like these from Rothwell.

I would make a few observations about the 405 sound:
- The midrange is superb and has the ability to convey the emotion of music very well indeed
- The treble and overall sound can be a little bright and hard. This is apparently mostly due to old op amps that have now been greatly surpassed by modern equivalents. You can either be sympathetic with speaker matching or consider various upgrades.
- The standard amp has a current limiter on it, intended to make it a safe and suitable partner for Quad electrostatics. This can be disabled (somehow!), probably as part of an upgrade. Once disabled the extra oomph is noticable.
- It's well worth getting a standard 405, however old, and then send it to be upgraded by someone like David Pritchard at Netaudio. I highly recommend it and the results are astonishing for the price. If you can, go for the full MK3 upgrade with DMPSU and you won't regret it. Alternatively, buy the one from Audio Emotion for £295 and feel better for the dealer warranty. Give Mark an email.

Good luck, I hope you get to enjoy the Quad's magic!

 

[lordmortlock]

Just thought I'd add I use a passive pre (rothwell) with a 909 and love the sound. I can vouch for the guys from Audio emotion too - excellent service.

 

[Anonymous]

You won't go wrong with a Quad 405 especially if you go for the latest Net Audio Version 3 boards and DMSU.

I also use a passive pre-amp, a very simple/minimilist one that I built myself using solid silver cable, elna switch and Vishay Dale stepped attenuator and high quality phonos. Before this I had a QED MA-34 passive pre-amp but believe me there is a big performance boost from an Alps blue volume control passive pre-amp to a stepped attenuator type. Also if you go for a stepped attenuator make sure the Quad 405/Net Audio Version 3 uses the Burr Brown OPA627s as opposed to the Analog Devices opamps as they are far more realistic and musical.

If you fancy buying a stepped attenuator passive pre-amp don't overlook Net Audio's Window pre-amp which offers very good value for money in terms of sound quality (or rather lack of it).

 

[Anonymous]

Good call on the Burr Brown OPA627s, they're def better than the Analogue Devices ones that come with the MK3 upgrade as standard. I must try a passive pre but I'm not sure about speaker cable lengths playing a role here.

 

[Anonymous]

General rule of thumb with passive pre-amps is to keep interconnects short between source -> pre-amp -> power amp so as not to affect impedences. If you can keep them under a metre then you should be ok.

 

[lordmortlock]

I'm using 0.8's and things sound good. I'm just plucking up the courage to attempt building a passive pre like yours Ben - first time I've attempted anything like that. I fancy using a wooden enclosure as I've got a nice Oak box that would be perfect. Any reason not to?

 

[lordmortlock]

Bargain 405 on P*inkf*sh now ...