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A vintage Quad thread.

Discussion in 'classic' started by Tony L, Dec 7, 2012.

  1. Tony L

    Tony L Administrator

    The 306 has plenty of poke, far, far more than a 303. Though as ever, if you want loud get proper loudspeakers! A good big speaker should be able to blow the windows out with a few Watts!
  2. Arkless Electronics

    Arkless Electronics Trade: Arkless

    It'll go as loud as a 45WPC amp would be expected to... Not "weak" in that sense.
  3. Tony L

    Tony L Administrator

    Except it doesn’t unless you keep the impedance 8 Ohms or above. Where an ideal amp doubles as impedance halves the 303 is 28 Watts into 16 Ohms, 45 into 8 and pretty much faints into 4 Ohms with just 28 again (ideal would be 90).

    The difference in power into 8 Ohms between a 303 and 306 is just five Watts, i.e. less than a db, but into typical modern ported speakers with reactive impedance dips the latter souns at least twice as powerful. With the right speakers I prefer the 303 as the midband is just so close to a Leak tube amp, Sugden class A or whatever, but the 306 is unquestionably a better all-rounder with modern speakers. To put it another way if you have Quad ESLs, big Tannoys, BC1s, LS3/5As or similar a 303 may be all the amp you ever need no matter how deep the pockets, but outside of that type of speaker it is of far less use.
  4. Arkless Electronics

    Arkless Electronics Trade: Arkless

    I was assuming its use with 8 Ohm speakers that suit it but if not then yes I can't argue on that point. Most of my listening experience with 303's has been with various Spendors, BCI, BC2 and SP1 in fact, plus some with ESL57's. As to just how good it can sound in ideal circumstances well I'm afraid my own experiences, to date, do not match yours. I have no doubt that you have vastly more subjective experience of 303's in different systems and with different speakers than myself though, hence "YMMV" :)

    The best I've ever heard 57's was at the same friends place using a Stereo 20 I'd rebuilt for him that was a bit special... fully regulated HT and separate regulators for the input and phase splitter stages plus a full set of Mullard M series Special Quality valves. Stunning.
  5. regafan

    regafan pfm Member

    I agree its not the best but I like it as an old set 'of its time'. It can be bettered sure by adding a nice pre of whatever flavour which I've tried and enjoyed, but going all out for modern performance isn't for me what having old Quad stuff is all about.
  6. Tony L

    Tony L Administrator

    There is something very right indeed about a good 303 driving either a pair of big Tannoys or LS3/5As. The former I guess because just so much stuff was recorded and mnitored on such a system, it just ‘unlocks’ the recording in a way few systems do somehow. Tannoys can sound rather fierce or grainy with more ‘modern’ tighly damped and extended amps, they just sound wrong to my ears. Likewise little sealed LS3/5As or JR149s really work as there is no excess brightness or grain, the mid is wide open and again the bass not unnaturally over-damped. This is most of my experience of the amp to be honest, though it is obviously a great match with original ESLs too, to the extent One Thing make a ‘Widget’ thing that is pretty much a 303 emulator (i.e. it reduces damping to give an easier and more period-correct sound).
  7. richgilb

    richgilb I'd have voted out lol....

    I have Spendor SP2/2 which I believe are easy to drive. On my 4th pair now!
  8. tyrant

    tyrant Active Member

    I've heard a 33/303 many times over the years at a friend's and I've compared my own 34/306 with a few other transistor amps (notably a Sugden A21 and an A48 both in spec according to Sugden, and a Bryston), and my impression pretty much matches Arkless's. Neither pairing is the last word in transparency, and the sound does have a softening and rounded off sense to it. That said, it's a sound that works well with vinyl. I also prefer the 34/306 over Sugden, but I use a digital source more often than a turntable (simply because I have a lot more CDs than records), and for that, a more modern amp sounds better to my ears. But it really is subjective.
  9. Tony L

    Tony L Administrator

    That ‘softness’ (I’d actually desribe it as a lack of glare or grain) works very well with digital IMO. I only really started loving CD once I went to a tube amp and for a long while felt I needed at least one tube between me and a digital source, but the 34/303 gets surprisingly close to that with none of the fuss. Also worth noting that I have big, efficient, exceptionally dynamic and powerful speakers, a lot of modern amps just sound a little artificial and too ‘in yer face’ via big Tannoy monitors to my ears. One thing I learnt a very long time ago with audio is that context is everything. After a certain level stuff isn’t really good or bad, it all just becomes about system synergy and getting the right voicing for your priorities. The 303 just happens to be a very good partner for Monitor Golds, they just work together.
  10. tyrant

    tyrant Active Member

    I can't be fussed with the tube fuss either. I've heard Tannoys sounding very good with a ballsy modern transistor amp (and not so good with a puny valve amp) but have never heard Monitor Golds with a 303. I'd love to hear that combination sometime.
  11. Dowser

    Dowser Learning to bodge again..

    I got a faulty 303 off someone here, repaired it and put it into my system (Croft Micro II upstream, ESL 63s down) and was not disappointed - ran it for a few months and was very happy. Then one day I put my ML No. 29 in to replace it - it’s a night and day difference, with the Levinson being better (as it should I guess).

    Lesson - the 303 does nothing wrong, which is important. But it is not the best amp in the world. I already know that my DIY SE valve hybrid monos beat the ML, and the outside temps are getting low enough now that I can soon re-I state them for the winter as heaters :)

  12. calorgas

    calorgas pfm Member

    I recently bought a tidy 303 that sounds great with my little Tannoy Eatons, but when I switch it on (at the mains) I get quite a big crack/thump and one speaker in particular moves back and forwards by a good inch.
    I've been reassured by someone who has lots of experience with these beasties that it's perfectly normal and nothing to worry about (the amp has been serviced previously). Thing is it really does bother me and despite being very happy with the sound quality once it's going, if I can't tame that switch-on behaviour then it's going to be a very short lived ownership. Anyone know how to stop this happening?
    I briefly had a 33/303 combo about 10 years ago that (iirc) that I played with into some Cheviots, and I don't recall this big ol' thump so is that somehow suppressed when you use it with a 33?
  13. Tony L

    Tony L Administrator

    No, not normal at all! On power-up a healthy 303 makes a very quiet ‘flup’ sound as the coupling caps charge, nothing loud at all. There is a switch-suppression cap soldered on the bottom of the transformer, my guess would be this has failed in yours, but I am in no conceivable way a electronics engineer. I certainly think your 303 needs a visit to someone wh knows what they are doing as what you describe is definitely not right.
  14. calorgas

    calorgas pfm Member

    Thanks Tony. Yeah I had a feeling that this couldn't really be normal. Maybe I didn't do a good enough job of describing the scale of the noise and cone excursion to the guy I referred this to. The noise I could live with but the way the cone shifts unnerves me.
  15. Tony L

    Tony L Administrator

    It really should only be a very gentle, quiet ‘flup’ even through high-efficiency speakers. Not scary at all even via my105db La Scalas! My guess is you have a fault condition. I’d get it seen to if I were you. If it is, as I suspect, the switch-suppressor, it is a couple of quid’s worth!

    PS I had to put one in my Leak Stereo 20 as that did the same thing, it is silent on switch on/off now.
  16. Robert

    Robert Tapehead

    That will have been me, and no an inch of excursion is certainly not normal!

    There is no relay or other muting circuit in a 303 so you will get a switch on pop - louder through high sensitivity 'speakers.
    That is normal.

    If the amp has been fitted with larger output coupling capacitors when serviced, that will also make the pop louder.
  17. calorgas

    calorgas pfm Member

    Thanks Robert.

    I guess it's difficult to describe what a pop or thump sounds like, but this sounds more like a sharp 'crack' followed by the large cone movement notably on one speaker.

    So anyway it sounds like the amp is not quite as happy as it could be. I've disconnected it all for now and reverted to my actives while I decides what to do next!
  18. Radfordman

    Radfordman pfm Member

    As Tony mentioned, the crack/thump is not normal. I have four 303's ranging from very early production to late production, none of them have this annoyance. You might want to check/ replace the four large capacitors, two for speaker coupling and two for smoothing the power supply. These do fail. It's strange that my oldest has original capacitors that are still OK, my latest production 303 needed them replacing.
  19. Tony L

    Tony L Administrator


    As stated earlier I’d also view the suppression cap on the transformer with great suspicion, especially if the 303 has already been serviced to some extent. It is the little grey cap on the far left of the picture, I’m pretty certain its job is to negate switch-on thump and I understand they do have a habit of failing, sometimes with magic smoke. They have been replaced in both my 303s (as has every capacitor). I suspect some folk who restore 303s miss this one!
  20. Radfordman

    Radfordman pfm Member

    I have a feeling that the capacitor beneath the mains transformer is there more to protect the rectifiers from any spikes, than to avoid switch on thump, but I could be wrong. Can anyone confirm or otherwise? It should be a cheap one to replace anyway.

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