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Inexpensive stable amp that can provide clean 50w?

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Apr 8, 2019
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#1
Hi everyone,

Thinking about buying Quad ESL 57 loudspeakers. If I do it will eat up most of my budget, so I'd need a cheap amp (150$ or under) that can drive them. I've read a lot about the ESL 57 being a difficult load. They don't need a lot of power - in fact you can damage the treble panel if you feed them too much. 50 Watt of clean power would be plenty. So the amp does not need too much power, but it should be stable with a difficult load.

Is there anyhting around that fit these needs? Reading Amir's measurements of the Topping TP60 and the FX Audio FX502S Pro is not encouraging. I was considering the Allo Volt+. But I assume that even if they state that it has 60 watt per channel, that may only be the case with high distortion.

If all other options are significantly worse I can wait and save for a Quad 303. That would cost around 300$ where I live. But if there is anything that provides similar sound quality and stability at half the price, that would be easier for me to handle. Thanks in advance for the help.
 

trl

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#2
Yamaha A-S301 is about 349 USD on Amazon now.
Usually, 50W of "clean power" probably means about 100W @1% THD, so A-S301 would be acceptable to fit your needs.
Worth mentioning that when a solid-state amp start distorting it will generate square-wave spikes pretty similar with DC-current that might get your speakers defective, so driving a set of speakers form a more power amplifier sometimes might be better.
 

Willem

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#3
I still have my original 33/3003 ESl 57 combination and after all these years the sound is still very hard to beat. In fact, I am listenig to them right now, waiting for the 2805s to be repaired. The Quad 303 is effectively your only safe bet for a power amp to drive these speakers. Many other amps will either self destruct or blow up the speakers.
 

bravomail

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#4
I read good things about SMSL AD18 and SA-50. But never seen any measurements or specs of those. So, if u feel lucky, punk, then u can try them! :)
 
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#7
Thank you all. 349$ is even more than a Quad 303 would cost me. I am hoping to find something stable for less money.

Nice recommendations bravomail. I'll search for info of users running Quad ESL 57s with these. The last thing I would want is to damage the speakers. As Willem wrote that's a danger with these electrostats. Without measurements nor specs it's hard to know what I would be getting. The good thing about the Quad 303 is that they are a known to work very well with the speakers. I guess I don't feel like risking too much.
 

jasonq997

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#8
Take a look at accessories4less.com . Go to the stereo receivers section. There are some Yamaha and Onkyo options there that should fit the bill.
 

Willem

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#10
I really wan to repeat my warnings. These speakers have a very nasty impedance curve plus a very reactive load. Just look at the manual. They are really hard to drive and the Q303 was designed specifically with the ELS 57 in mind. Moreover, drive them with more than 33 Volt and the panel will arc.
 
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#11
Thanks for the recommendations and the warning. The pair I am looking at had a complete rebuild by One Thing Audio. They have clamp boards fitted that offers protection from arcing. But still they remain a difficult load. Looks like the Quad 303 is the safest option, unless I can find reports of a cheaper amp driving them securely.
 
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#12
Thanks for the recommendations and the warning. The pair I am looking at had a complete rebuild by One Thing Audio. They have clamp boards fitted that offers protection from arcing. But still they remain a difficult load. Looks like the Quad 303 is the safest option, unless I can find reports of a cheaper amp driving them securely.
I have a restored and upgraded QUAD 303 from the 1970's - it's my 'reference' amp, and definitely my favorite class A/B amp. The 303 uses a 'tripple cascade' output topology, which makes this amp special even by today's standards. Get one, you won't regret it.
 

LarsS

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#13
I really wan to repeat my warnings. These speakers have a very nasty impedance curve plus a very reactive load. Just look at the manual. They are really hard to drive and the Q303 was designed specifically with the ELS 57 in mind. Moreover, drive them with more than 33 Volt and the panel will arc.
Totally agree, pls listen to this sound advice. Friend of mine bought a pair of Quad's (new) in the late seventies, as adviced by seller he paired them with a Sansui amplifier, great amps for anything but Quads. Turned out the Quad's got destructed by the Sansui, saw firsthand the sparks from the Quads, small holes in the panels.

Anyway, seller took his responsibility and friend got new speakers & amp. Paired new Quads with an Electrocompaniet integrated amplifier, worked great!
 

Blumlein 88

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#16
The Quad ESL 57's are a tough load, but I've owned, and own some worse. I had a circuit with an led to light to tell me when I approached too much voltage. Yours will have the protection board which is good though maybe hard on the amp if you activate it.

Good tube amps really do okay with these. I ran mine for a time with an old Fisher tube integrated of about 20 wpc. But those likely aren't cheap. The 303 is probably one of the cheaper sure safe options. And old Dyna ST70 would be nice too. Any solidly made amp of 75 wpc or less should be fine on it actually. It is voltage which kills them and you'll need about 75 wpc amps to have that much voltage. So keep it to 50 wpc is probably good for these. Though if I got a deal on a good 75 wpc amp I wouldn't be afraid since you have the protection boards.

Even though they have a low treble impedance, they have a high impedance at lower frequencies so a huge amount of current isn't needed as music has most power concentrated below 500 hz. The Parasound up thread would be good choice I think. I don't know about suggesting class D amps. If some of the newer models with the higher switching frequency then sure. But older versions (which will be cheaper 2nd hand) might be a poor choice due to the reactance just above 20 khz.

So sorry, I don't have a magic recommendation to make. Cheaper new amps that aren't tested are simply too much of a shot in the dark. What tests Amir have done indicate some of these specs on such amps is fantasy (or marketing....same thing).
 
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#17
Amazing info. Thanks everyone. So I'm looking for inexpensive, clean 50 Watt. The Zamp looks like an option, if I can find one used in my vicinity. And I'll check out Parasound.
Other than that it is surprisingly hard to find a suitable model, because the lack of measurements. The companies specs for class d amps are not very trustworthy, so I won't rely on that.
Looks like the Quad 303 is a good choice and a safe bet, even if slightly over budget.
 
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#18
As an ESL-57 owner I would fully endorse a 303 as a sound and safe choice, good used ones seem to always be on the market. I run my ESL's with a Quad 405-2 but have the necessary circuit limiters in place to ensure safe operation. While these speakers are known for their difficult load and extremely small listening window, they really do deliver the goods music wise. You will easily be albe to position the speakers and your listening spot because when you hear it you will know instantly.
 
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#20
i think the only way to get clean 50W is to pick a powerful amplifier so you can use it without reaching peak distortion levels. something advertised with 100-150W should do, either assembled or diy boards
 
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