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Quad 303

graham55 said:
It's interesting to see the QUAD 303 and 405 gradually rebuilding their reputations these days. In the 1970s, they were considered greatly inferior to Naim's early (and much more expensive) 160 and 250 models.
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Some of that has to be down to the type of speaker popular at the time. A Quad 303 would be utterly hopeless into a pair of Isobariks, Saras or whatever, it was designed to drive the nominally 16 Ohm ESL. There is no question that the Naims have a lot more power, current and grip, and were far more suited to the inefficient heavy plastic cones in sealed boxes so popular at the time. The 405 had the misfortune to arrive on the scene at the point speakers started getting really hard to drive, e.g. Kef 105s, Gale 401s etc. It was never great in this company, but fine with ESLs or working 24/7 into a pair of big Tannoys in a recording studio, or into high impedance LS3/5As etc. When people are rediscovering Quads these days I suspect it is very much in the context of ESLs or very easy to drive vintage speakers such as the Klipsch my 303 is hooked up to. Context is everything - I don't think even those of us with a soft spot for them would describe them as great all-rounders.

Tony.
 
Tony, that's an interesting insight. I use Naim amps into my ESLs and, to my ears, they sound significantly better than QUAD amps!
 
I still have the 34/606, which I used to use with ESL63s. I now have a new stacked pair and a new single pair of ESL57s, on the end of Naim amps. I've also heard 57s with new QUAD valve amps. The Naims have considerably more 'oomph'!
 
graham55 said:
Tony, that's an interesting insight. I use Naim amps into my ESLs and, to my ears, they sound significanty better than QUAD amps!
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I've never heard ESLs driven by Naim, but I've heard folk say it's a good combo from the Nait 1 or 2 upwards.

The vast majority of my Quad amp experience is with the 303, I've never owned any other Quad amp. I started off with a second hand 33/303 in 1978 and another 303 ended up finding it's way to me a couple of years ago. It was such a nice tidy one I found it a job in my second system rather than selling it.

The 303 is strange amp to get a handle on IMO. I'd argue it is more than it first appears. This amp is absolutely not about impact or showboating, it doesn't know how to jump up and down shouting 'look at me' the way some hi-fi kit does, so you either need to get beyond that, or reject it at this point. Assuming it's happy driving the speakers in question it just takes a background role quietly and gets on with things (if it's not happy driving the speakers it sounds soft, dull and lumpy / leaden in the bass).

Once you get used to this rather understated presentation it's actually a very communicative little amp. Mine is on most of the day either doing the TV sound, playing 6 Music, R3 or R4 from the SkyBox, streaming from Spotify, iTunes or internet radio, and it just keeps drawing me into the music without highlighting issues with the sources (well it's clear 6 Music is compressed to hell, that's a given). It brings to mind the (incorrect) stereotype of tube amps being warm, smooth and a little rose-tinted - the 303 is all this to a degree - if it's happy it is astonishingly easy to listen to. I've a lot of time for the 303, though I'd hesitate to give it a blanket recommendation as I'm certain many folk would just hate it / think me insane.

Tony.
 
The 303 has a capacitor coupled output, which used to be common, but is now a rare design choice.

This means the output impedance rises at low frequencies, and will interact with the speaker load quite differently to the way say a Naim or 405 would. This will be particular true for low tuned bass reflex designs; you expect it to sound different to direct coupled amps, and with some loads it could give rather one-note bass.
 
graham55 said:
I still have the 34/606, which I used to use with ESL63s. I now have a new stacked pair and a new single pair of ESL57s, on the end of Naim amps. I've also heard 57s with new QUAD valve amps. The Naims have considerably more 'oomph'!
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Would be interesting to try a 303 on the preamp that you are using. It may be the 34 letting the side down. I rarely use my Quad 44 or 33 Preamp.
 
Radfordman, I admire your confidence, but I don't think that the dear old 303 (or any number of them) is in the same league as the 135s and 250 in my system.

Nor should you expect it to be, given the respective prices.

Graham
 
Good page on the interaction of the 303 and '57:

http://www.audiomisc.co.uk/57and303/interact.html


From personal experience - yes the Nait2 does a remarkably good job at (then!) low cost, although its not the last word in anything. An amp with near-zero output Z (A Deltec 50S with feedback taken from the speaker terminals) provided a heckuva lot more of everything

- And a mint Audio Innovations 500 with Border Patrol PSU made anything on Verve and Riverside, 1957-1959 real in a way that had me reaching for mail-order orange cardies, Brylcreem and a Brough Superior. An effect sadly limited to a very narrow range of material else I'd have long left these shores and grown a barbe, and a nasty pipe habit.
 
The 303 works best into easily driven speakers with a reasonable impedance and a bit of sensitivity.
 
mudlark said:
The 303 works best into easily driven speakers with a reasonable impedance and a bit of sensitivity.
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I think it's impedance that bothers it more than sensitivity as it's a decent enough performer into LS3/5As & JR149s (about 84 db and 11 or 15 Ohms). The tendency towards smoothness and warmth is certainly an asset with high efficiency horns like my Heresys (95db, 8 Ohm minimum impedance dip) which were clearly voiced for tubes.

Tony.
 
the design of the 303 was miles in front, and if it could be manufactured to modern standards it would out sell most things including the naimes
 
PigletsDad said:
The 303 has a capacitor coupled output, which used to be common, but is now a rare design choice.

This means the output impedance rises at low frequencies, and will interact with the speaker load quite differently to the way say a Naim or 405 would. This will be particular true for low tuned bass reflex designs; you expect it to sound different to direct coupled amps, and with some loads it could give rather one-note bass.
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Good points, and a fairly easy fix these days.
The coupling caps are 2kuf, a relatively small value and a compromise when driving low impedance loads as the LF roll-off and lack of damping are exacerbated.
The choice will have been driven by cost, cap physical size and typical loads of the day (60s and 70s).

Substituting something like 6.8kuf, which because comparable value electrolytics are now smaller, will help greatly.
It won't overcome the the peak current limitation which is set by the regulated power supply but it will give better performance.

To pick up on Graham and Tony's points, speaker loads did change but Quad reacted by relaxing current limiting on the 405 in 1982. Still no powerhouse but the revised 405-2 will perform decently into moderately difficult loads, ie 4 Ohm and not too reactive. The current limiting was designed to be program dependent, so while something like a NAP250 will muller a 405-2 reproducing sine waves on the test bench, reality in a domestic situation is quite different.

With regard to performance being hampered by cost constraints, this questioned was tackled by the 405s co designer, Mike Albinson soon after the amp was released. Essentially, giving a 405 the ability to perform arc welding duties was perfectly possible but the level of overkill engineering required was seen as bringing no benefit to the end user driving loudspeakers of the day.
In the 70s, insensitivity was the issue rather than ever plunging load impedance - that came in the 80s.

Well worth reading Mike Albinson's interview.
We have it in our reference section along with some other papers from those influential to Quad over the years including Peter Baxandall and of course Peter Walker.
Quad ESL site is also a good source of info, and has the Albinson interview - http://www.quadesl.org/Album/InterviewsReviews/MikeAlbinson/mikealbinson.html
 
I've been using a pair of Quad 11's for around 4yrs now with excellent results. I once owned a 405 MkII, although good, the bass was a little thin/blouse'y for me.

Anyone know how a standard Quad 303 would compare against Quad 11's..??
 
ishmac said:
I've been using a pair of Quad 11's for around 4yrs now with excellent results. I once owned a 405 MkII, although good, the bass was a little thin/blouse'y for me.

Anyone know how a standard Quad 303 would compare against Quad 11's..??
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They are supposed to be similar in character, but I haven't heard the two.
 
tones said:
To my (admittedly ancient) ears, more identical (I have both and use both on a regular basis).
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Also identical to the ears of various industry luminaries gathered to form the listening panel for Peter Walker's famous blind test in the late 70s.

Bridged IIs, a 303 and a 405 into Yamaha NS1000s.
 
Robert said:
Bridged IIs, a 303 and a 405 into Yamaha NS1000s.
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I've read the article, and I'm amazed - I'd have believed it into ESLs given that's what all three amps were designed for, but I'd have expected all of them to be pretty weak into NS1000s - I thought they needed some current!

Tony.
 
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