Summits c/w Pass X150.5 Amplifier

[edwinr]

Hey guys.

Just to let you know, I bought a Pass Labs X150.5 the other day. It's been 'burning in' for a couple of days. I had a Mark Levinson 432 before that which I had some issues with. I won't go into that here, but after returning the amplifier I reverted to my old Proceed BPA2 while I was looking for a new amplifier.

Here are some brief thoughts on the sound quality of these three ampliifiers as used with the Summits.

Proceed BPA2: 125 Watts per channel into 8 Ohms with a power increase into 4 ohms and some ability to drive 2 Ohms for brief periods. A very well built and slightly 'dark' sounding amplifier. A little muddy in the bass in absolute terms with good dynamics. Wide soundstage but imaging a little blurred. Power wise, the Proceed had no problems driving the Summits to loud levels. This is a good budget choice for those wanting to move to a low cost pre-power option with either Summits or Vantages.

Mark Levinson N0. 432: Whew! What can I say? This monster is built like a tank with power to burn. 400 watts per channel into 8 Ohms, 800 into 4 Ohms and very good ability to drive into 2 Ohms if required - but it can get hot doing this. This amplifier is NOT neutral sounding. It has a slightly dark quality (a little like the Proceed) with very substantial bass punch. HUGE dynamics. A wide soundstage with pinpoint imaging. Voices sound a little recessed but everything is there, if a little restrained. The Mark Levinson has no problems driving anything. I reckon you could hook a small town up to it and it would supply all electricity needs without raising a sweat. One thing I should say; I am now thinking the Mark Levinson is not a good match with Summits. It only comes into it's own when driven hard with say... Revels or something like that. The magic first watt is not Mark Levinson's forte.

Pass Labs X150.5: This amplifier is not a monster like the Mark Levinson. Still, it does okay with 150 watts into 8 Ohms and increasing to 300 watts into 4 Ohms. I have no specifications or measurements of it's ability to drive 2 Ohms. The amplifier is pretty much of Mark Levinson build standards but this is where similarities end. The Pass does not have the Mark Levinson's persistent bass punch. This was evident on first listening. Don't get me wrong, the bass is there but it's more like Chuck Norris rather than Mike Tyson. Chuck will only hit when he needs to and you won't get up after being hit. Mike just keeps punching - and it hurts but it's not going to kill you (not straight away anyhow). I think maybe the Mark Levinson tends to deviate from the strictly neutral - this is not entirely what I desire and is not the reason I bought Summits in the first place. The imaging and the soundstaging of the Pass amplifier is of Mark Levinson standards but there is no 'hash' or 'haze' to interfere with the music. It's like the music is coming from deep space. There is much more 'air' to the music and little details seem to be more easily heard than through my other two amplifiers. I am wondering if this particular Pass amplifier (the lowest power in the range) is more suitable for more sensitive speakers like the Summits. I know the Pass runs in pure Class A for 50 or 60 watts - the side heat sinks run VERY hot even at idle. So perhaps the Pass is more capable of delivering the magic 'first watt' than my other amplifiers - this is not to say the Pass X150.5 won't boogie. It can go VERY loud driving insensitive speakers, but we're talking about Summits here. Speaking of which, the Summits seem to soak up what the Pass provides and initial indications are that this amplifer and speaker make a very nice combination.

Just some thoughts... here's a pic:

 

[sleepysurf]

Very interesting analysis. I've never heard the Pass X150.5, but George (Rampage60) has the X350.5 driving his Odysseys, and it clearly has power to spare. He is getting prodigious bass out of his system using a Paradigm Servo 15 sub.

In a recent (limited) amp face-off using Craig's Summits, and Wadia 581i source direct-to-amp, his Electrocompaniet AW220 monoblocks delivered slightly tighter bass than my Belles 350A Ref. The midrange and highs were pretty darn close. However, we used balanced interconnects from the Wadia to the Electrocompaniet, and RCA outputs to the Belles, so that *might* have accounted for the difference.

Hopefully, folks at regional get-togethers will conduct more component "face-offs" and report back their opinions. That would also be an interesting session to arrange for our next Annual Get-Together!

I'm looking forward to attending the RMAF in a few weeks, but doubt many rooms will be demo'ing multiple amps!

 

[Gordon Gray]

Glad you like the Pass Labs amp

Hi edwinr,

Haven't had the chance to audition many SS or tube amps but your observations about a "black" background mirror my experience with the 250.5.

One of the things I've noticed about this lack of noise is how much more you can hear at the ppp (very low) volume level. The slightest / most subtle sounds on a well recorded classical CD just pop as if the volume level was at 90db versus the 70db or whatever it is during soft passages.

I've also noticed, since having the Pass amp since December 06, that my average listening volume level has dropped substantially indicating to me that the Pass Labs amp is able to project an audible / better defined sense of detail and resolution, even at lower volume levels.

Best regards,

GG

 

[edwinr]

Well, day 2 of more extended listening has been and gone.

I'm not quite sure what to think. I had to advance my previous 25 and 50 Hz bass settings a little. The Pass is either a little leaner than the other amps, or it's more accurate in the bass.

The level of detail is outstanding. I have to say it is definitely better than the Mark Levinson - the Proceed amp is not in the same ball park. I know you guys have heard this before... but I'm hearing detail in recordings that I have never heard before. Also the imaging is rock solid.

The Summits are obviously enjoying the higher quality signal, and I guess my ears have to adjust to the extra detail I'm hearing. But I can't help thinking this amplifier is a little brighter than I'm used to...

 

[Gordon Gray]

Yup!

Hi Edwinr,

Regarding your last post and adjusting the 25 and 50hz adjustments on your Summits, that's exactly what I did when I first installed the Pass Labs amp in my system.

I previously had the Classe CA150, which is clearly not up to your Levinson amp, but found the adjustments appropriate to tune the overall tonal balance to my liking. Brought out a bit more of the warmth of the midrange and such.

FWIW, I called Pass Labs regarding the dreaded "burn in" time issue. The person I spoke with said, although they bias the units before they ship, 100 hours is it. He also said that owners have called and said that longer burn in times were audible. I agree. It just keeps getting better.

I've made very small adjustments to the x-over settings (1/4db +/-) over the past several months. Although extremely small, it allowed me to fine tune the overall sound of my Summits to something that I listen to on a nightly basis, with this "I've arrived" feeling in my gut.

Hope you enjoy the music with your new amp.

GG

 

[edwinr]

Hi Gordon,

Thanks for your post.

I have now established that my other amplifiers had/have some bass lift. I replugged the Proceed back in and it's definitely 'colored' in the bass. My old Classe was probably the same - and maybe to a lessor extent, the Mark Levinson No. 432!

The Pass is much more neutral and clean. Actually 'clean' is probably the best word to decribe the entire sound from the new amp. I telephoned my dealer and he said the Martin Logan dealer in Hong Hong is now selling Summits with the Pass Labs amplifiers as a recommended system.

It's easy to get caught up with the bass issue - 'more is better'. Some earlier amplifier designs were intended for 1980's speakers where bass lift was needed to get the best out of passive designs. This is why I had to trim the Summit bass controls so drastically with the other amplifiers. I still couldn't entirely trim out some bloom that really annoyed me with certain music. Now this bloom is gone.

The Summit, of course, is a new millenium design. I regret trying to 'penny pinch' when I first bought my speakers. I should have bought an up to date amplifier (like the Pass) to match my Summits in the first place...

Edwin.

 

[Audioseduction]

At least you have the Pass now and get to enjoy it with the marrige of the Summits. :music:

 

[Joey_V]

Edwin,

Sweet!

That first magic watt is very crucial in getting the best out of your speakers. I am definitely surprised that you stated that the ML may not have that magic first watt down though...

The more I read about Pass, the more I wonder how it sounds compared to the Plinius. Both seemingly have great first watts and the best of both run Class A.

Joey

 

[edwinr]

It's gone!

I can't believe it! It's gone!

The Pass Labs X150.5 has vanished!

Yes folks. It's been over two weeks since I inserted Nelson Pass' creation into my system. My initial reservations have faded into obscurity. The X150.5 has completely disappeared as a component. I can see it. I can touch it. I can feel the prodigious amount of heat from the beast, but I can't detect it in my system.

I have never experienced any component that could become so completely transparent - so neutral. The initial leanness has slowly developed into warmth that the Summits just lap up. It's almost tube like. Except the bass slam is something that no (affordable) tube amp could hope to emulate. The top end has similarly sweetened - it's like honey.

But the most startling thing is the sheer amount of detail the Summits now throw at me. For example, lately I have been listening to Arrau playing Chopin's Nocturnes. I can now hear every little sniff and breath as Arrau massages the ivories. He's a great artist but at times now he sounds like Glenn Gould. This is a bit disconcerting but if it's on the disc, I want to hear it.

This just goes to show, for me, how resolving the Summits can be when fed an appropriate signal. They sounded okay before, but now they sound like something entirely different...

Also there may be some merit in the claim that some components need to 'burn in' before any serious listening or evaluation is undertaken.

 

[Gordon Gray]

I concurr!

Hi Edwin,

Found your latest comments on the X150.5 to again mirror my experience. Based on numerous thoughts posted on this website regarding the synergy between ML's and Pass Labs, the amp and speakers appear to be quite the good match.

FYI, I installed the Black Diamond Racing Mk 3 wide pits between the spikes and my wood floor yesterday to eliminate the speaker / floor vibration issue as recommended by Rich. All I can say, after a few hours of listening, is Oh My! Perhaps I'll post my specific observations on this addition in the near future. Suffice to say, the Summits responded.

Best regards,

GG