passive pre with KWA-150 SE

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Shredder

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passive pre with KWA-150 SE
« on: 20 Aug 2017, 04:45 pm »
Morning. I have a Lampizator Atlantic Plus Balanced DAC, a Cary SLP-05 pre, an MW KWA-150se, and Aerial Model 9 speakers. Because that setup has too much gain (Lampi 3v output, Cary 12-16db gain, MW 26 db gain, Aerial 90db efficient), I have been using Endler attenuators to tame the gain. They actually improve the sound in certain respects, in particular by lowering the noise floor and eliminating some treble glare. However, they also reduce the dynamics.

In the long-term, I am seriously considering Daedalus Ulysses speakers. I assume that the high efficiency will only exacerbate the gain problem.

A lot of Lampi owners use passive pre-amps. The Tortuga's are especially well regraded. I was wondering whether anyone had tried a passive with the 150se? I would love to know whether passives work well with  MW.

One other option may be to have Cary reduce the gain to 0db. I have an email to Cary on that topic. Anyone here reduce gain on pre to address execs gain issue?

Thanks in advance for any input.

aldcoll

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Re: passive pre with KWA-150 SE
« Reply #1 on: 20 Aug 2017, 06:29 pm »
Just last month at a get together with the Puget Sound folks we hooked a Atlantic with volume control straight to my Modwright KWA 150 S E.   It was a magical sound and experience.

There are people that say a Pre Amp will sound better in the string.  We had a couple on hand but neglected to give it the test.

Alan

Shredder

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Re: passive pre with KWA-150 SE
« Reply #2 on: 20 Aug 2017, 07:23 pm »
With Daedalus speakers?

aldcoll

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Re: passive pre with KWA-150 SE
« Reply #3 on: 20 Aug 2017, 07:49 pm »
None other then the new Apollo's.

Sonic Bliss :thumb:

Alan

Shredder

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Re: passive pre with KWA-150 SE
« Reply #4 on: 20 Aug 2017, 09:22 pm »
Nice, I hope to hear those at RMAF.

mresseguie

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Re: passive pre with KWA-150 SE
« Reply #5 on: 20 Aug 2017, 10:07 pm »
Shredder,

Alan very reluctantly agreed to babysit my Apollos while my wife and I are traveling. His Pans (and their great sound) played a big role in my decision to buy Daedalus speakers. The Atlantic DAC, KWA150SE, and Apollos make fantastic music together.

Michael 

Shredder

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Re: passive pre with KWA-150 SE
« Reply #6 on: 20 Aug 2017, 11:22 pm »
Nice, we are definitely on the same track audio wise. Enjoy your travels.

Shredder

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Re: passive pre with KWA-150 SE
« Reply #7 on: 21 Aug 2017, 12:29 am »
BTW, how do your Apollo's compare to the Ulysses? I have heard the U's a few times.

aldcoll

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Re: passive pre with KWA-150 SE
« Reply #8 on: 21 Aug 2017, 01:07 am »
To be honest I have never heard the Ulysses.  As I was buying Lou s intro model I didn't want to start speaker envy.  He offered to plug them in and I ran out the door.

A couple trips ago we listened to all of his speakers but the Ulysses.  And as I am simply the way station for the Apollo's till Michael gets back west.

It was the magic of the new 10 inch driver.  Lou did have the chance to play the 2 pair of Apollo's at the same time and his comment was ,  The bass..........

I did get my Pans out and powered them along with the Apollo's.  There are about 3 major steps in crossover difference.

The Apollo's have a sealed crossover housing on the rear of the speaker.  And with a 40 inch tall speaker it is half the height and all the width.  I have seen the crossovers he has built and they are massive and beautiful.  No pictures on threat of death.

His new cabinets have only 1 90 degree corner.

And I will just mention we are slipping away from a Modwright message.  But still powered by Modwright.

Come buy for a eclipse watch listening party.

Alan

mresseguie

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Re: passive pre with KWA-150 SE
« Reply #9 on: 21 Aug 2017, 02:49 am »
Fear not! I'll tie it back into Modwright. Thanks to our recent G2G and the listening session in Lou's shop, I truly understand the Modwright magic. The KWA150SE is in my top few list of SS amps to consider for my future home in Vancouver or Camas, WA.


Rusty Jefferson

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Re: passive pre with KWA-150 SE
« Reply #10 on: 21 Aug 2017, 01:59 pm »
...One other option may be to have Cary reduce the gain to 0db. I have an email to Cary on that topic. Anyone here reduce gain on pre to address execs gain issue?.....
I think this is usually impractical, or not possible,  but.......I had the exact same issues you've been going through with 102db speakers, reasonably high gain amp,  and an active pre. I switched to a passive (First Sound) and a buffer and was very happy with the results. Low noise floor, better dynamics, smoother highs. That's until I borrowed an LTA Microzotl.  Initially, it had too much gain, but after talking to Dave Berning on the phone, he told me I could reduce gain by simply replacing the 12at7 input/drivers with 12au7 with no negative effects. Boom!  Magic happened.  Low gain, super low output impedance, so great dynamics and drive, and eliminated the buffer. Dead silence from my speakers too. Never sounded better.

Shredder

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Re: passive pre with KWA-150 SE
« Reply #11 on: 23 Aug 2017, 05:05 pm »
So, Cary can't reduce the gain to 0. it can, however, reduce it by 3db and Lampi can reduce by another 3-6. According to Cary, reducing the voltage on the Lampi will prevent the Cary from being overloaded. That is apparently the cause of distortion from the mismatch.

Rusty-why the buffer? Doesn't the MW have a high enough input impedance?

Anyone else have experience with passive and MW?

Thanks.

Rusty Jefferson

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Re: passive pre with KWA-150 SE
« Reply #12 on: 26 Aug 2017, 02:04 am »
.....Rusty-why the buffer? Doesn't the MW have a high enough input impedance?

Anyone else have experience with passive and MW?

Thanks.
Sorry, not using MW amplifier(s), but am bi-amping with 2 ss amps that have 33kohms and 47kohms respectively input impedance,  so it was necessary to lower the output impedance of my preamp.  First with the buffer/passive arrangement,  then with the Microzotl, which has only 2-3ohms of output impedance and can drive any load. Great dynamics.

I've seen your other threads in the Lampi circle and see you're running balanced.  You'd have to call Mark at LTA and see if he can build one with balanced outputs.