Quad 303-What speakers work well with it?
- Thread starter reilly.martin2
- Start date
To echo what has already been posted, 8 ohm (or higher) speaker impedance is a must. Also it is a good idea to play to the strengths of the 303, i.e. go for speakers that have an equally transparent midrange. Interesting to hear that Martyn is using one with P3ESRs - which come close to panels on transparency, but are a less than ideal load.
While I love the aesthetics of the 33, it is the weaker part of the 33/303 combination.
I moved on from the 303 having bought low-impedance speakers that it just couldn't cope with, however the clarity and natural presentation linger as fond memories. I think of the 33/303 effect as "puffy clouds of music" and the 303 remains an absolute champ if your goal is to spend hours enjoying music. The Net Audio upgrades do make a difference - especially the replacement regulator board - but IMO it is best to avoid irreversible modifications.
BTW one can work around the CD signal level issue on a standard 33 by using the tape input - the input voltage is adjustable on the tape adapter board.
The amazing thing with these amps is the amount of thought that went into the "internal aesthetics" - it's very much easier to work on the innards of a 33 or 303 than anything else I've had to open up.
While I love the aesthetics of the 33, it is the weaker part of the 33/303 combination.
I moved on from the 303 having bought low-impedance speakers that it just couldn't cope with, however the clarity and natural presentation linger as fond memories. I think of the 33/303 effect as "puffy clouds of music" and the 303 remains an absolute champ if your goal is to spend hours enjoying music. The Net Audio upgrades do make a difference - especially the replacement regulator board - but IMO it is best to avoid irreversible modifications.
BTW one can work around the CD signal level issue on a standard 33 by using the tape input - the input voltage is adjustable on the tape adapter board.
The amazing thing with these amps is the amount of thought that went into the "internal aesthetics" - it's very much easier to work on the innards of a 33 or 303 than anything else I've had to open up.
They do. But then so do all the samples of the ls3/5a, all have high impedances. They just love the 303.
Shane2468
pfm Member
True, paskinn.
Just out of curiosity, have you tried/heard a 303 that contains NET Audio parts?
S.
No I haven't heard any mods to the 303. I'm a bit of a 'purist' about this. I think that these classic designs work very well as they are. Once 'modded' they change character. But as there are still loads of 303's out there, it probably doesn't matter if a few get modded. Plenty to go round.
Tony L
Administrator
I'm the same. Mine is currently entirely stock and I'm afraid of fiddling with it as I suspect in many ways it's actually it's so called "weaknesses" (less than tight bass, slightly rolled-off HF, smoothness etc) that makes it such a usable amp with my tube-loving Klipsch speakers. I've actually got a box full of fancy 303 bits that I've not used including a Net Audio reg board and two expensively rebuilt amp-boards! I think I'm just happy with it as-is, though in some ways I'm tempted to land another one to temporarily upgrade just to see if I prefer it or not.
One thing I find interesting is the contrast between the 303 and 306. I prefer each in a different speaker context. The 306 is more extended in the bass, crisper, tighter and quite a lot quieter (one notices this with 104db speakers!). Into the Tannoys it is the better amp - it just wakes them up and they sound clean and punchy. With the Klipsch it's all too much, and even though it's very clean and quiet, it just sounds too lean and dry somehow - it's just not easy to listen too. The 303 just does it's getting out of the way thing. The JR149s make for a score-draw. Both amps sound different, but both very acceptable, though the 306 clearly has more power on tap should one want it.
If I throw the Leak Stereo 20 into the ring, and assuming I ignore noise (the Leak is rather hissy and hums a bit, it needs a good service), the 303 sits at an exact mid-point between it and the 306 - it really is a solid-state amp with an easy-going tube-like character: not as fat, liquid and enveloping as the Stereo 20, but not as crisp and punchy as the 306. It's a middle-ground I like a lot. As such I'm planning to keep it stock but well serviced. My only criticism is I wish it was as quiet as the 306, there is just a little hiss and hum evident from the La Scalas, but they'll find it in just about anything due to the crazy high efficiency.
Shane2468
pfm Member
Thanks Tony L & Paskinn.....Yes, I agree!
This looks interesting- http://rover.ebay.com/rover/1/710-5...0001&campid=5338728743&icep_item=201037418857
S.
This looks interesting- http://rover.ebay.com/rover/1/710-5...0001&campid=5338728743&icep_item=201037418857
S.
This site contains affiliate links for which pink fish media may be compensated.
Curious if any shoot-out or empirical AB has been conducted between 303 and 50E. I know for fact that Peter Walker said, "303 is a better amp than the 50E" However, based on audition of the 303 and 50E in isolated occasions, to my ears, coupling of an output transformer to a SS amplification in 50E does give certain charm (beyond words) over the 303.
Martyn Miles
pfm Member
I contacted H.T. Baker and received a comprehensive and balanced reply. re. servicing my 303.
M Miles.
Robert
Tapehead
I've never heard a pair of 50Es, though I'd certainly like to, they are what Abbey Rd used back in the 1970s:
You can see one lurking on the floor under the left Tannoy Lancaster.
I've got my first pair coming in for a service soon. I'll let you know how they perform. The owner drives them with a 34 and says the combination works well.
Fed from a TD124/Dynavector 507/Decca.
His 124 has a few issues with rumble so I've pointed him to your mammoth 124 rebuild thread.
Thanks to everyone for the kind words of recommendation. Much appreciated!
Darmok
pfm Member
Mmmm, Nice!
Isn't the Quad 50E just the same as a Quad 303 with one channel disabled?
Yes, I know there is an output tranny in the 50E.
I have done this in the past with good quality stereo power amps, (Not Quad) bought two and dis-abled one channel in each = much better reproduction 2x mono'd than a single stereo.
Much Fun.
Robert
Tapehead
Mmmm, Nice!
Isn't the Quad 50E just the same as a Quad 303 with one channel disabled?
Yes, I know there is an output tranny in the 50E.
I have done this in the past with good quality stereo power amps, (Not Quad) bought two and dis-abled one channel in each = much better reproduction 2x mono'd than a single stereo.
Much Fun.
Yes its half a 303 with a matching transformer.
Running half a stereo power amp by disconnecting one channel if often better than trying to bridge the two channels of a stereo amp, unless you need the extra power.
Darmok
pfm Member
A friend has some 50Es, they sound very good. A 303 without the limitations, and bulletproof due to the OP transformer.
Most of them have been gigged and the casework is hammered. Their values are low enough that it's not worth getting a non-abused 303 and swapping cases. Shame.
Most of them have been gigged and the casework is hammered. Their values are low enough that it's not worth getting a non-abused 303 and swapping cases. Shame.
reilly.martin2
Active Member
Never seen any 50E's for sale, from Tony's photo obviously widely used by BBC and no doubt got hammered in regular use?
Mmmm, Nice!
Isn't the Quad 50E just the same as a Quad 303 with one channel disabled?
Yes, I know there is an output tranny in the 50E.
I have done this in the past with good quality stereo power amps, (Not Quad) bought two and dis-abled one channel in each = much better reproduction 2x mono'd than a single stereo.
Much Fun.
Not really: the QUAD 50E is not quite a mono version of the 303. It does use a different circuit particularly in the output stage.
The use of on output transformer with a centre tap on the primary side means that you can set up a fully symmetrical output stage using two NPN transistors rather than a more typical Quasi-complimentary output stage used in the 303. PNP transistors were rather expensive and sometimes a bit unreliable in the early days of solid-state amplifier design. The output stage arrangement of a 50E reminds me very much of a typical valve amplifier, they never quite invented a PNP valve.
The 50E also uses a single rail PSU with a series choke and an unregulated 88-volt line voltage rather than the fully regulated PSU used in the 303. The 50E does however regulate the line voltage going to the earlier input and VAS stages. Without the use of current sources on the earlier stages power supply rejection ratios are very poor, a regulated PSU is pretty much de rigueur.
One thing the 303 and the 50E do share (besides the casework) is the use of a pre-driver transistor or triples in the output stage. This should deliver better load tolerance and distortion figures into lower impedance and more reactive loads.
Ive never heard a 50E and Ive only ever seen one in the flesh so I cant comment on their performance but I would be curious to try one out.
LPSpinner.
Radfordman
pfm Member
I think, from memory, the 50E has slightly greater output power than a single channel of a 303.
mr sneff
pfm Member
I've just had a 303 that I picked up cheaply modified by Net Audio. The actual work took way longer than anticipated and cost a lot more than I was originally quoted, but I ended up with the full Mk 3 upgrade. I must admit than when I (eventually) got the 303 back I was underwhelmed by the result. Fortunately it still sounded like a 303 to me, so I felt that at worst it was an expensive waste of time. So I just shrugged and carried on listening to music. After about a month I found myself thinking, "the system is sounding pretty good". Bass was more controlled and the highs a bit more extended, but still smooth. Soundstage seemed to extend beyond the speakers; I only have a small room and the speakers are close to the wall, so I can't really comment on soundstage depth (I'm using a pair of single driver John Blue JB3s, BTW). Rhythmically everything just seemed to have more 'get up and go'.
