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Power handling capability of original Quad esl 57s

After many years of hearing about how wonderful the original Quad esl 57s are, I finally found a near mint late serial number pair. I'm in audio heaven! I used to own the 63s and the 989s, and these are much better ( in the sweet spot).

Now my question: what is the power handling capability of the 57s? There seems to be some confusion here. According to the original manual, it is safe to use any amplifier as long as it does not produce more than 33 volts at any impedance. This is an interesting specification because it does not differ from the 63s.

Ok, let's do some math. At 8 ohms, 33 volts into 8 ohms gives us
33^2/8 = 136 watts! At higher imoedances, power must drop, so at 30 ohms, the speaker can only take up to 30 watts.
Ag insider logo xs@2xtuttles

Showing 3 responses by ct0517

ct0517's avatar
ct0517
2,041 posts
 
Tuttles

I share your enthusiasm for these speakers.

I have tried different SS / Tube amps with mine.

The original 303 amps they came with were good for 28 wpc at 16 ohms and 45 at 8 ohms.

I have a 405 amp.
Quad recommends resistors be put in the 405 100 wpc amp to limit its output with them.

Does anyone know what power this limits the 405 amp to - I am assuming about 50% ? This would answer the question as well.

I agree with Stanwal that they need very little power to sound "full".

And I am surprised at how good they sound with the 33 pre and 405 amp. These vintage Quad gear are readily available.
ct0517's avatar
ct0517
2,041 posts
 
The 405 works well. The sound I heard taking it easy with a Music Reference RM9 was amazing. One knowledgeable member has commented on the protection circuit in my review of them.
ct0517's avatar
ct0517
2,041 posts
 
Lists are great tools but just first base in this hobby.

I have no idea how good the hearing is of anyone that comes up with these lists or what their room, speaker placement and other gear is - in that order. I trust my ears only unless I am helping a friend set up speakers, in that case its his or her ears.

I listen around 85-90db with my 57's. Which means peaks above that getting close to their limits of 100db from what I have heard. They are a ridiculously easy load to drive compared to my other speakers.

As far as the 405 is concerned when put in a system that taxes that amp - I dont know never tried - maybe that is where some of the remarks come from. In my system with my panels I hit my db levels very easily. Its a piece of cake for the properly functioning 405 I think. For what you can buy them for anybody starting out with these speakers I think would be foolish to at least not give it a try with matching Pre and listen to what Quad "wanted you to hear". Then when u are ready get that nice little tube amp - there will always be someone waiting to buy your 405.

YMMV - My opinion only
Cheers
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