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The pure bliss of Quad 57 on triode SET

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Pelliott321

Post subject: The pure bliss of Quad 57 on triode SET

Posted: April 19th, 2016, 7:45 pm

Joined: January 15th, 2015, 7:19 am
Posts: 1737
Location: Baltimore MD

I had a brief listen at Walt's after he repaired a friend's pair 57's that needed power supply rework and work in the very weird xover circuit.
The Quads were stock and in very good physical condition.
The sound was glorious, bested anything I heard in a long time

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pboser

Post subject: Re: The pure bliss of Quad 57 on triode SET

Posted: April 19th, 2016, 9:25 pm

Joined: April 4th, 2016, 4:07 pm
Posts: 60

What was the amp? Conventional wisdom ( take it for what it's worth!) says one needs about 15 watts for the Quads.

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SoundMods

Post subject: Re: The pure bliss of Quad 57 on triode SET

Posted: April 19th, 2016, 11:06 pm

Joined: July 24th, 2015, 4:17 pm
Posts: 1786
Location: Parkville, Maryland

The Quads were a pleasant surprise for me when I was finished the work and just listening. They were dated September 1969.

The Quads are beyond transparent and sweet -- they are not there at all. Very remarkable for a design that originated in 1954 and was tweaked in 1957 for stereo.

Modifiers out there are ruining the Quads. Peter Walker for want of a better description of his talent was a genius! Other than better 560-pf caps in the audio modules, the Quads that I worked on are stone stock.

My amps.? Modified Cary CAD-805C Rev. 1 amps. Cetron 845s, driven by Psvane 300Bs, with gain provided by cascoded G.E./IBM 0528s. Although the Carys can push 50 watts the Quads did not need that kind power to blossom.

I can't wait for the owner's reaction tomorrow when he auditions these beauties and takes them home. They will be missed.

Attachments:

File comment: Quad 57 ESL HV Bias Supply Installed

0A Quad 57 ESL HV Supply Installed.jpg [ 1.58 MiB | Viewed 16316 times ]

File comment: Quad 57 ESL Replacement HV Bias Supply

0A Quad 57 ESL HV Supply.jpg [ 1.35 MiB | Viewed 16316 times ]

File comment: Quad 57 ESL Upgraded Audio Module

0A Quad 57 ESL Audio Module.jpg [ 1.67 MiB | Viewed 16316 times ]

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Walt

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TubeDriver

Post subject: Re: The pure bliss of Quad 57 on triode SET

Posted: April 22nd, 2016, 8:03 am

Joined: March 12th, 2013, 11:12 am
Posts: 739

I heard a beautiful set of 57s driven by 300B amps. It was in a TINY Washington DC apartment and music was only jazz at fairly low levels but in spite of the limitations, it had a wonderful sound.

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SoundMods

Post subject: Re: The pure bliss of Quad 57 on triode SET

Posted: April 22nd, 2016, 9:03 am

Joined: July 24th, 2015, 4:17 pm
Posts: 1786
Location: Parkville, Maryland

The owner brought his Quad II amps. over to hook up in my system but they were stock and I didn't have adapters. That was the bad news.

The good news is that I looked under the hood. WOW! The build quality was way over the top including solid-wire Teflon-insulated wiring.

Re-builders are replacing that wiring with hook-up wire. WTF?! Not to mention other atrocious "improvements."

The Quad II amps. were designed specifically for the Quad speakers by band-width limiting the output (bass) to no lower than 40-Hz.

Trivia -- The tweeter panels start to get into trouble when the +/- signal level exceeds 1.5-kV which equates to 20-watts input from an amplifier.

I was able to fill a 15' X 15' living room with serious in-your-face sound from those modest screens with no ill-effects. My guess is that they were fed no more than 10-watts.

The overall tonal balance was right on just as Peter Walker designed them with their little feet just elevating them off the floor.

Right now I am suffering with separation anxiety -- They were that good.

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Walt

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