How many watts for Quad ESL 57's

[Wakefield Turntables]

I have a Radford STAIII 25, which rather unsurprisingly pumps out 25 Watts. But how many watts are really needed to make these beasts sing and is it better to try going the old Monoblock route? Maybe Quad II's ?? The ESL's are great, they have just been freshly worked over by one thing audio. Looking forward for some suggestions as alternatives to the Radford (which I'm keeping!!)

[Ali Tait]

Should be fine. I used to run a pair with a Sugden A21 at 7 w/ch, and a pair of WAD monoblock 300b amps at 18w/ch. The Quads won't take too much power. Have yours still got the clamp boards fitted?

[DSJR]

If the 57's have their own limiters inside (as OTA, or Quad about these), then within reason, you can use any good amp able to drive the load as long as the amps don't ring into capacitive loads. A good friend bought a pair of 57's in 1978 with a 405, which had its own limiters fitted. Eleven years later, the 405 was re-capped and new mk2 boards fitted minus limiters. The 57's had their own limiters put in and the sound was VERY much opened up we found. later, I took the 405-2 and my friend bought a 606, which drove the 57's without risk at semsible volumes. In fact, the rattling casework on one 57 is the main limiter and I suspect the whole setup (with 66 pre) will need fettling before too long. A lovely and endearing system this one...

Enjoy the Radford. The Quad II's are charming, but not in the same league IMO. You could possibly "upgrade" to a fettled 303 if you want to try summat different

[stewartwen]

My Mum uses Quad 57 loudspeakes, yes really. And she had it from the horses mouth that they will take 50 watts.

[StanleyB]

The ESL has a crow bar limiter that comes in at 50Watts into 8 Ohms. It's best not to reach that point on your amp sine the ESL protection system is a very aggressive one.

[DSJR]

Stan, isn't that the 63's. Forgive me if I'm incorrect here?

[The Grand Wazoo]

The Radford is as near a perfect match for your speakers as has ever been made - stick with it unless you can find a pair of Radford MA15's or some Mark Levinson ML2's.

[Dr Bunsen Honeydew]

If the 57's have their own limiters inside (as OTA, or Quad about these), then within reason, you can use any good amp able to drive the load as long as the amps don't ring into capacitive loads. A good friend bought a pair of 57's in 1978 with a 405, which had its own limiters fitted. Eleven years later, the 405 was re-capped and new mk2 boards fitted minus limiters. The 57's had their own limiters put in and the sound was VERY much opened up we found. later, I took the 405-2 and my friend bought a 606, which drove the 57's without risk at semsible volumes. In fact, the rattling casework on one 57 is the main limiter and I suspect the whole setup (with 66 pre) will need fettling before too long. A lovely and endearing system this one...

Enjoy the Radford. The Quad II's are charming, but not in the same league IMO. You could possibly "upgrade" to a fettled 303 if you want to try summat different

Quad 57 ESL's are not a capacitive load, why do you think they are?

[Dr Bunsen Honeydew]

The ESL has a crow bar limiter that comes in at 50Watts into 8 Ohms. It's best not to reach that point on your amp since the ESL protection system is a very aggressive one.

Too right that is why they call it a crowbar, it throws a dead short circuit across the amplifier terminals. Best to disable it. Designed for the 63 the 57 didn't have it, but ones sent back to Quad for service were fitted with it. Not only will it fry most solid state amps even if they have fuses (as it operates quicker than any fuse) but it also makes the speakers sound worse.

[DSJR]

Quad 57 ESL's are not a capacitive load, why do you think they are?

63's were claimed not to be, but perceived wisdom from the times always claimed the 57's to be capacitive, which is why I believe amp test after amp test used a 2uF load to see how the amps performed, citing Quad 57's as the reason.