Quad update

[Bonky]

The problem of fake semiconductors from China is real and present... and far more widespread than you may imagine. I would be pleasantly surprised if there were no fakes in the cheapest Chinese kit. Very definitely caveat emptor!

OK, but surely fake transistors and diodes would soon fail or show-up in poor performance. The manufacturer says the pcb is Chinese, but, and perhaps I'm wrong here, he doesn't state that the populace of the board is.

Has anyone any evidence that there are errors in these pcb boards...as someone has opined?

I find it somewhat amusing that, having just been interested in another forum on £90 audiophile fuses...where subjectivity seems to be key....that here SQ seems to be marginalised.

Thanks


Again, has anyone either hard evidence of poor Chinese workmanship on this kit, and/or actually listened to this amp?

[Light Dependant Resistor]

Hi
Like you I have tried 405.2 and 306, the 306 is a better device and better design.
The Chinese clones are either poor copies with design faults of a 405.2 which I alerted
to in another thread , or based on a 405 Mk1

There is nothing hugely wrong with an original Quad 405 or 405.2, but a 303 generally sounds better
but a 306 better again.

I would not waste my time with clones rather,put money available into another 306 and use one channel of each for
your amplification needs. This is what I do like a mono block, just using one channel of each amp.

Cheers / Chris

[Bonky]

Hi
Like you I have tried 405.2 and 306, the 306 is a better device and better design.
The Chinese clones are either poor copies with design faults of a 405.2 which I alerted
to in another thread , or based on a 405 Mk1

There is nothing hugely wrong with an original Quad 405 or 405.2, but a 303 generally sounds better
but a 306 better again.

I would not waste my time with clones rather,put money available into another 306 and use one channel of each for
your amplification needs. This is what I do like a mono block, just using one channel of each amp.

Cheers / Chris

Thanks Chris (and others). More food for thought ...and cheaper too!

BW
Richard.

[mikmas]

I did some searching around 405 clones a year or two back when I was looking - in the end I got an original 405-2 in good nick (eBay - £200) and it's done well.

This is a good thread about the topic, albeit relating to clone boards rather than complete amps. Note post #6 relating to the inherent fault in some (mentioned earlier).

http://www.diyaudio.com/forums/solid...surements.html
"The 405 clone boards faithfully reproduce the well-known error on the original 405-1 schematics and PCBs: the output Zobel network is grounded to the input signal ground (which is isolated from the power ground by a 10R resistor), not the power ground as it should be, explaining why I experienced catastrophic oscillation which destroyed a tweeter the first time I plugged one of these things in without anything connected to the signal input ground."

Likely that the bloke on eBay you are looking at has sorted this problem but worth bearing in mind.

Personally I've had no problems whatsoever with the original I bought but yes, it can be pot luck given the age of these beasts.

[Arkless Electronics]

OK, but surely fake transistors and diodes would soon fail or show-up in poor performance. The manufacturer says the pcb is Chinese, but, and perhaps I'm wrong here, he doesn't state that the populace of the board is.

Has anyone any evidence that there are errors in these pcb boards...as someone has opined?

I find it somewhat amusing that, having just been interested in another forum on £90 audiophile fuses...where subjectivity seems to be key....that here SQ seems to be marginalised.

Thanks


Again, has anyone either hard evidence of poor Chinese workmanship on this kit, and/or actually listened to this amp?

There are many variables here. Sometimes they use a die from older lower spec transistors, sometimes even ones rated for half the power of the ones you think you are buying. Failures can and do happen. You may not notice the difference in performance.
I NEVER buy semiconductors from ebay or similar sources as the chance of them being fake is just too high. I pay maybe 5 times as much for guaranteed quality from approved stockists.

I'd avoid the 303 if I were you. The worst of the Quad amps in many ways. They do have a following but personally I wouldn't give one house room... other than as an objet d' art with a 33 pre and FM3 tuner in a bedroom or workshop system. They don;t produce any "nasties" such as hard or "transistory" sound or anything like that, they just fail to deliver on grip, speed, transparency etc and although they can sound ok in isolation comparison with a modern amp soon puts them in perspective!

[RothwellAudio]

All looks a bit gash to me. Quite an untidy layout inside.

Yes, I agree, not the tidiest of layouts. In itself that may not be a problem but it would undermine my faith in the product.

[Idlewithnodrive]

I've owned at least a couple of each of the 303's, 306's and 405-2's and my order of preference goes 405-2 first (by a long margin), then the 306 and a fair way behind the 303. I would buy a good condition 405-2 and get it serviced by Quad (£70).

[agk]

The problem of fake semiconductors from China is real and present... and far more widespread than you may imagine. I would be pleasantly surprised if there were no fakes in the cheapest Chinese kit. Very definitely caveat emptor!

Yep. The amp I currently enjoy is known to employ some fake WIMA caps as it comes from the factory. Mine fortunately has been sorted but it's a definite issue to be aware of.
Not to say all fake caps are bad caps but you have no way of knowing.

[Gordon Steadman]

I've owned at least a couple of each of the 303's, 306's and 405-2's and my order of preference goes 405-2 first (by a long margin), then the 306 and a fair way behind the 303. I would buy a good condition 405-2 and get it serviced by Quad (£70).

Just goes to show...... the exact reverse of my taste! Can there be a definitive answer to these things?

My Leak Stereo 20 has suddenly making 'orrible distorted noises and without France's resident guru (how dare you move back the UK) it has been necessary to put it on the spares pile.

The only two amps I have here I will trust with the 57s are a 303 and a 306. I know that I preferred the 306 to the 405/2 I no longer have. It was very quickly established that the 303 is the one that makes music and offers more insight with the 57s. They were designed to compliment each other. I tried both 303s I have and they both did the same job.

So clearly, choosing a speaker relies on being able to drive it with your chosen amplifier before laying out the readies.

[DSJR]

Jez will diss or confirm I'm sure, but the current dumper circuit is very fussy around the 'bridge' and crap design here ruins the performance. Not an easy circuit to 'clone' successfully and Quad themselves went though several layout changes until the first mk2 boards came along (issue 7). Quad did have new replacement boards not that long ago (issue 10 I seem to remember)... Link to mk1 updates below.

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


Must be just me, but I always found the 306 gutless, even with other preamps. The 303 has it's place, but not necessarily in a modern system (my old speakers were voiced using a 303 with its particular and sonically way of doing things so it kinda makes sense as a base reference in my particular case).

606mk2's aren't hugely expensive these days and I still think they're bloody good - the mk1 may need some updates as they could take a while to 'warm up' and lose the grain heard on cold-switch-on I remember, something the mk2 avoided right from the off on the samples I demo'd.