Pass labs for Sasha's


I just purchased a pair of Wilson Sasha's and I'm looking for opinions on the right Pass amp to drive them. I previously had Wilson W/P 7's with Pass XA 100's (not .5) which sounded great but lacked a tight bass control.
stan550
My family and I have enjoyed Wilson speakers and Pass amplifiers since we purchased a pair of 5.1 Watt Puppies and an Aleph 0's amplifier.

We integrated a home theater system with our 2 channel stereo system - so our entire family would enjoy our investment. We also have Wilson speakers (Watch II center and sides, and the W/P 5.1's) and Pass amplifiers (3 - X-250.5's) in our theater system.

Currently have a pair of Sasha I speakers. When we first got them, we drove them with a Pass XA-30.5. My wife and I preferred it to the X-250.5 by a significant margin.

Our set up is optimized for stereo with theater added to our system. The 30.5 was much more life like - it's weakness was with bass dynamics due to it's lack of power (when compared to the 250.5 or in absolute terms). We've since upgraded to a pair of 200.5's and we're very happy with them.

While I haven't heard the 100's, it's affirmed that they have challenges with delivering higher current, which is what Nelson addressed with the .5 series. Since the Sasha's dip to a ~ 2 ohm load, the 100's may not perform their best with them.

When we purchased our Sashas, we had similar questions about Pass amplifiers and read here on the Audiogon forum about the Lamm 1.2 Reference being preferred by a good Audiogon member. My wife and I visited Chris Foreman at Innovative Audio / Video (in NYC) to listen to it and we also got to listen to Spectral amplifiers.

We found the Lamm to have a slight emphasis in the bass which Chris confirmed, and we found the Spectral amps slightly (dry) lacked the portrayal of the natural acoustic of the performance we became so accustom to.

Any of the XA-.5 series amplifiers will work well. After speaking with Kent English and listening for ourselves - the higher models offer improved performance, more than just the increase in power output would imply.

The lower powered 30.5 and 60.5 models will not maintain their performance with dynamic bass (percussion). Anything at the 100.5 and above will present a much more natural performance.

Regarding the newest .8 series, I haven't had the pleasure to listen to them yet but only "hear" good things about them - and there's a few in depth comparisons some good Audiogon members were kind enough to share.

Hope this helps you enjoy your music, TJF.
Thank you, that was exactly the feedback I was looking for.

Hi Stan.
From 70hz to 250hz the Sasha's have a very heavy current demand on an amp, they are 2ohm and have a -45 degree phase angle at 70hz.

So an amp has to maintain god current delivery to get the "very best out of them", this means amps that can "almost" keep doubling their wattage for each halving of impedance load 8ohms down 4ohms down to 2ohms. They are efficient at 91db so the amp can be a 50watter into 8ohms, so long as it keeps doubling down to 2ohms.
Like the old ML2 monoblocks they were only 25watts but I bet they would of sounded magnificent on these Sasha's

EG:
8ohms---- 150watts
4ohms---- 300watts
2ohms---- 600watts

These types of amps will extract the very best from the Sasha's. This type of amps will be BJT (bi-polar) output stages, as no Mosfets will do the doubling act like a BJT amps can, and definitely no tube amp can.

Cheers George
I'm trying to determine if the xa 100.5 will do the job or do I need to step up to the 160.5. The speaker have their duties split between music and movies.
Stan,

Your question of will the XA-100.5 do the job needs to be clarified. How big is your room? What type of music do you listen to? How loud do you like to listen? All will impact what will meet your needs and satisfy you.

While I'm schooled and licensed as an engineer, I gave up explaining things scientifically quite some time ago (not that there's anything wrong with that). I prefer to explain how equipment sounds. If someone asks - circuit design, component selection, circuit board topology, power supplies & filtering, component configuration, dampening factor, slew rates etc. can be discussed. I believe it's simpler and easier to describe what works well and how a component sounds.

George is spot on referencing an amplifier needing to be able to supply power into a low impedance load. This is especially critical for amplifiers of (relatively) lower power output. However if an amplifier has a (relatively) higher power output, say 100 watts instead of 30, it can still provide adequate power (current) for low impedance loads even though it doesn't quite double it's output current.

While the Pass 30.5 suffered reproducing dynamics, it never embarrassed itself. It simply wasn't as convincing in a comparison to a live performance.

If listening to the 100.5 and 160.5 with Sashas isn't possible, I'm confident to say the 100.5's, even the most demanding music (anything with big dynamics) with a moderate sized room and lifelike volume, won't disappoint. The 160.5's will always sound better but upgrading is another story. We got the 200.5's on a deal I couldn't pass by - we intended to purchase the 100.5's.

Hope this helps, TJF.
They are both Mosfet Stan, this is what the Stereophile bench tests say about XA160 which is also Mosfet.

"The actual output power at clipping 118W into 8 ohms, 59W into 4 ohms, and 29W into 2 ohms.
Combinations of low-impedance speakers and large rooms should be avoided with the XA160."

As you can see, no doubling at all down to 2ohm. And this is what your speakers demand to sound their best.

Cheers George
Stan and George,

I believe George is referring to the Pass XA-160 amplifier, which is now succeeded by 2 generations - the XA-160.5 and the XA-160.8 amplifiers.

I did mention earlier that Nelson addressed the limited current ability of the XA series with the XA.5 series, which perform much better.

May I recommend getting to listen to the Pass amplifier(s) you're considering with Sasha speakers? Even if you have to travel a weekend to do it - I believe it would be worth the investment.

Healthy and Happy New Year to all, filled with listening to music that stirs our senses and moves our soles.

Only good wishes, TJF.
Thank you