The Last Amplifier Project - Pass Labs X600.5 Monoblocks

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DarqueKnight
DarqueKnight Posts: 6,765
edited April 2013 in Electronics
Over the past few years I have been evaluating higher powered amps (and saving coins) to replace my Parasound Halo JC 1 monoblocks. My research kept leading me back to the Pass Labs X600.5 monoblocks. I will take delivery of a pair next week.

Specs:

600 watts into 8 ohms (400 watts for JC 1)
1200 watts into 4 ohms (800 watts for JC 1) (my modified SDA SRS 1.2TL's are 4 ohm equivalent speakers)
Class A watts: 80 (compared to the JC 1's 29 watts class A)
Weight: 132 pounds (64 pounds JC 1)

x600_5_main__large_zpsfa8c7cce.jpg

x600_5_alt1__large_zps49ddb6e4.jpg

x600_5_rear__large_zpsdd65b29d.jpg

001Smith2CHEquipCab-s8_zpsb38eb12e.jpg

The X600.5 is taller than the JC 1's, but has approximately the same size footprint, so it will easily fit in the same cabinet space. The X600.5 idle heat sink temperature is only a little more than the JC 1's (122 degrees F compared to 118 degrees F). If everything works out, the JC 1's will be traded in.

I'm hoping the X600.5's will be great compliments for my Pass XP-30 line stage preamp and Pass XP-25 phono preamp. I actually was planning to make this purchase next year, but the dealer (Reno HiFi) made me an offer I could not refuse.
Proud and loyal citizen of the Digital Domain and Solid State Country!
Post edited by DarqueKnight on
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  • headrott
    headrott Posts: 5,484
    edited April 2013
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    Oh boy Ray! Can I come over!?:lol:
    Relayer-Big-O-Poster.jpg
    Taken from a recent Audioholics reply regarding "Club Polk" and Polk speakers:
    "I'm yet to hear a Polk speaker that merits more than a sentence and 60 seconds discussion." :\
    My response is: If you need 60 seconds to respond in one sentence, you probably should't be evaluating Polk speakers.....

    "Green leaves reveal the heart spoken Khatru"- Jon Anderson

    "Have A Little Faith! And Everything You'll Face, Will Jump From Out Right On Into Place! Yeah! Take A Little Time! And Everything You'll Find, Will Move From Gloom Right On Into Shine!"- Arthur Lee
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  • nooshinjohn
    nooshinjohn Posts: 25,124
    edited April 2013
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    But for these beauties I would make an exception. Congrats man. I cannot wait to read your review.:cool:
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

    “When once a Republic is corrupted, there is no possibility of remedying any of the growing evils but by removing the corruption and restoring its lost principles; every other correction is either useless or a new evil.”— Thomas Jefferson
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  • monepolk
    monepolk Posts: 1,141
    edited April 2013
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    Very nice, enjoy!
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  • DarqueKnight
    DarqueKnight Posts: 6,765
    edited April 2013
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    headrott wrote: »
    Oh boy Ray! Can I come over!?:lol:


    Sure. I could use some help unpacking and setting up those beasts, plus I need help setting up blind tests, lest I be accused of imagining performance improvements:razz:
    nooshinjohn wrote: »
    Tubes Rule!!!

    Tubes rule? But...but...but...Nelson said he designed the X600.5 to have the sweetness, air, layering, and sound staging of the best high end tube designs, yet with the bass slam, articulation and detail of the best high end solid state designs. We'll see.:cry:
    Proud and loyal citizen of the Digital Domain and Solid State Country!
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  • zingo
    zingo Posts: 11,258
    edited April 2013
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    Very nice, and I would hope that system would have good synergy... :cheesygrin:
    Jake
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  • Dawgfish
    Dawgfish Posts: 2,554
    edited April 2013
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    Those are freaking amazing! Honestly I'd give my left one to hear the big boy SDAs and that much super high quality amplification! Listening to them is probably going to be a religious experience. Congrats!
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  • pitdogg2
    pitdogg2 Posts: 24,624
    edited April 2013
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    I'm so jealous
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  • bobsauto49
    bobsauto49 Posts: 973
    edited April 2013
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    That's a pretty set-up! Beautiful Amps!
    "Everything I ever did in my life worthwhile I caught hell for"
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  • falconcry72
    falconcry72 Posts: 3,580
    edited April 2013
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    Those could definitely fit the bill as "Last" amplifiers. There's not a whole of gear I'd say that about. Congrats, man!:cheesygrin:
    2-Channel: PC > Schiit Eitr > Audio Research DAC-8 > Audio Research LS-26 > Pass Labs X-250.5 > Magnepan 3.7's

    Living Room: PC > Marantz AV-7703 > Emotiva XPA-5 > Sonus Faber Liuto Towers, Sonus Faber Liuto Center, Sonus Faber Liuto Bookshelves > Dual SVS PC12-Pluses

    Office: Phone/Tablet > AudioEngine B1 > McIntosh D100 > Bryston 4B-ST > Polk Audio LSiM-703's
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  • NJPOLKER
    NJPOLKER Posts: 3,474
    edited April 2013
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    Hey Ray

    I can see all is going well and happy to see your spending money on good things.

    It seems to me the weakest link in your system is the 1.2tl's. Can that be true?????

    Like all the others here I really have enjoyed reading your reviews/findings and look forward to your thoughts on your new power plant.
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  • Drenis
    Drenis Posts: 2,871
    edited April 2013
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    Impressive, period.
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  • thsmith
    thsmith Posts: 6,082
    edited April 2013
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    Congrats !
    Speakers: SDA-1C (most all the goodies)
    Preamp: Joule Electra LA-150 MKII SE
    Amp: Wright WPA 50-50 EAT KT88s
    Analog: Marantz TT-15S1 MBS Glider SL| Wright WPP100C Amperex BB 6er5 and 7316 & WPM-100 SUT
    Digital: Mac mini 2.3GHz dual-core i5 8g RAM 1.5 TB HDD Music Server Amarra (memory play) - USB - W4S DAC 2
    Cables: Mits S3 IC and Spk cables| PS Audio PCs
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  • Toolfan66
    Toolfan66 Posts: 16,947
    edited April 2013
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    Awesome!!!

    Congrats Ray!!
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  • DarqueKnight
    DarqueKnight Posts: 6,765
    edited April 2013
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    NJPOLKER wrote: »
    It seems to me the weakest link in your system is the 1.2tl's. Can that be true?????

    Yes, that could be true.

    I keep expecting to reach "the wall" whereby differences in high performance gear can no longer be perceived, but I have not reached it yet. The 1.2TL's have "grown" along with my electronics upgrades. If the 1.2TL's were still in their stock form, then yes, they would be a weak link. I still continue to audition speakers...patiently waiting for that magical moment when a new pair speakers entices me to replace my hot-rodded 1.2TL's.

    On the surface, it might seem inefficient to run a 20+ year old pair of speakers with top of the line electronics and cables. It is no more inefficient than taking a 20+ year old Porsche and updating its engine and other components and ending up with a car that is the equal in many respects, and is the superior, in some respects, of contemporary sports cars.

    When you crack open many of today's-well regarded high end speaker designs, sometimes you find exotic drivers and custom crossover components, but often you find high quality, but off the shelf, parts. It is how those off the shelf parts are implemented in the speaker design that makes the magic happen. When you crack open my 23 year old SDA SRS 1.2TL's, you find:

    1. Audioquest 15 gauge solid core premium quality wiring,
    2. premium capacitors, which are designed to minimize electrical and mechanical noise,
    3. premium resistors, which are designed to minimize electrical and mechanical noise,
    4. premium inductors, which are designed to minimize electrical and mechanical noise,
    5. a custom designed and extensively vibration damped crossover circuit board, with over-sized, heavy-weight copper traces,
    6. damped driver baskets and drivers and tweeters tightly coupled to the baffle board with steel retaining rings.

    How many modern high end speaker designs have all of that, or even half of that?

    Even more important than all of the physical design improvements is the patented SDA interaural crosstalk cancellation circuit. The purpose of stereo reproduction is to recreate a three dimensional illusion of a musical performance. No other speaker in existence does that as well as SDA's, with their wide and stable sweet spot and panoramic sound stage.:biggrin:
    Proud and loyal citizen of the Digital Domain and Solid State Country!
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  • Conradicles
    Conradicles Posts: 6,045
    edited April 2013
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    Very nice amps! Have fun!
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  • EndersShadow
    EndersShadow Posts: 17,543
    edited April 2013
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    Hey Ray... you have a problem though now...

    You cant end every review with:

    Someday when I am more dedicated to audio than I am now....

    I think "someday" has arrived :wink:
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
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  • txcoastal1
    txcoastal1 Posts: 13,134
    edited April 2013
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    Can't wait for the deatails...'cause know shows or explains the details like you

    those are beasts
    2-channel: Modwright KWI-200 Integrated, Dynaudio C1-II Signatures
    Desktop rig: LSi7, Polk 110sub, Dayens Ampino amp, W4S DAC/pre, Sonos, JRiver
    Gear on standby: Melody 101 tube pre, Unison Research Simply Italy Integrated
    Gone to new homes: (Matt Polk's)Threshold Stasis SA12e monoblocks, Pass XA30.5 amp, Usher MD2 speakers, Dynaudio C4 platinum speakers, Modwright LS100 (voltz), Simaudio 780D DAC

    erat interfectorem cesar et **** dictatorem dicere a
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  • Big Dawg
    Big Dawg Posts: 2,005
    edited April 2013
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    Beautiful amps, Ray, congrats.
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  • heiney9
    heiney9 Posts: 25,092
    edited April 2013
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    I think you will be very happy and as good as the JC1's are...........I predict you will like the X600.5's even better.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • [Deleted User]
    [Deleted User] Posts: 1,394
    edited April 2013
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    Ray,
    Congrats on the amps, a beast with beauty for sure! I look forward to your review, as always.

    Halen
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  • NJPOLKER
    NJPOLKER Posts: 3,474
    edited April 2013
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    DarqueKnight wrote: »
    Yes, that could be true.

    I keep expecting to reach "the wall" whereby differences in high performance gear can no longer be perceived, but I have not reached it yet. The 1.2TL's have "grown" along with my electronics upgrades. If the 1.2TL's were still in their stock form, then yes, they would be a weak link. I still continue to audition speakers...patiently waiting for that magical moment when a new pair speakers entices me to replace my hot-rodded 1.2TL's.

    On the surface, it might seem inefficient to run a 20+ year old pair of speakers with top of the line electronics and cables. It is no more inefficient than taking a 20+ year old Porsche and updating its engine and other components and ending up with a car that is the equal in many respects, and is the superior, in some respects, of contemporary sports cars.

    When you crack open many of today's-well regarded high end speaker designs, sometimes you find exotic drivers and custom crossover components, but often you find high quality, but off the shelf, parts. It is how those off the shelf parts are implemented in the speaker design that makes the magic happen. When you crack open my 23 year old SDA SRS 1.2TL's, you find:

    1. Audioquest 15 gauge solid core premium quality wiring,
    2. premium capacitors, which are designed to minimize electrical and mechanical noise,
    3. premium resistors, which are designed to minimize electrical and mechanical noise,
    4. premium inductors, which are designed to minimize electrical and mechanical noise,
    5. a custom designed and extensively vibration damped crossover circuit board, with over-sized, heavy-weight copper traces,
    6. damped driver baskets and drivers and tweeters tightly coupled to the baffle board with steel retaining rings.

    How many modern high end speaker designs have all of that, or even half of that?

    Even more important than all of the physical design improvements is the patented SDA interaural crosstalk cancellation circuit. The purpose of stereo reproduction is to recreate a three dimensional illusion of a musical performance. No other speaker in existence does that as well as SDA's, with their wide and stable sweet spot and panoramic sound stage.:biggrin:


    Beautiful

    Exactly what I was hoping or thinking your findings would be. Another true to life testament on the potential of Polk SDA's Kind of makes me want to take a trip down to New Jersey and pick up my SDA SRS2's right now!!

    Thanks for your response and congratulations on another job well done.
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  • hochpt21
    hochpt21 Posts: 5,423
    edited April 2013
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    Weight: 132 pounds (64 pounds JC 1)

    :eek:

    Those are beautiful.
    2 ChannelTurntable - VPI Classic 2/Ortofon 2M BlueAmplification - Rogue Audio Cronus Magnum II, Parks Audio Budgie PhonoSpeakers - GoldenEar Triton 17.2 Home TheaterDenon AVR-X3300W; Rotel RMB-1066; Klipsch RP-280F's, Klipsch RP-450C, Polk FXi3's, Polk RC60i; Dual SVS PB 2000's; BenQ HT2050; Elite Screens 120"Man CaveTurntable - Pro-Ject 2.9 Wood/Grado GoldAmplification - Dared SL2000a, McCormack DNA 0.5 DeluxeCD: Cambridge AudioSpeakers - Wharfedale Linton 85th Anniversary; LSiM 703; SDA 2A
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  • steveinaz
    steveinaz Posts: 19,522
    edited April 2013
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    I believe you have found the holy grail! Very nice.
    Source: Bluesound Node 2i - Preamp/DAC: Benchmark DAC2 DX - Amp: Parasound Halo A21 - Speakers: MartinLogan Motion 60XTi - Shop Rig: Yamaha A-S501 Integrated - Shop Spkrs: Elac Debut 2.0 B5.2
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  • D_M
    D_M Posts: 175
    edited April 2013
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    DK,

    You mind listing the amps you have evaluated? I'm just curious about your journey. Thanks.
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  • cstmar01
    cstmar01 Posts: 4,424
    edited April 2013
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    Very cool and congrats! Always have wanted to get my ears on a full Pass system like that. Look forward to your impressions on it!
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  • DarqueKnight
    DarqueKnight Posts: 6,765
    edited April 2013
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    EndersShadow wrote: »
    Hey Ray... you have a problem though now...

    You cant end every review with:

    Someday when I am more dedicated to audio than I am now....

    I think "someday" has arrived :wink:

    No, I'm not there yet. There is always something "better" around the corner.:cool:
    D_M wrote: »
    DK,

    You mind listing the amps you have evaluated? I'm just curious about your journey. Thanks.

    A discussion, with pictures, can be found in this thread from 2008:

    Higher-Power-Amplification-For-SDA-SRS

    You can see that this has been on my mind for a while. I had narrowed my choices to the Bryston 28BSST2 and the X600.5. The 28BSST2 offered more power (1000 wpc into 8 ohms) and costs 13% less than the X600.5, but the 28BSST2 is optimized for 8 ohm speakers. I was not fully confident about its performance with my 4 ohm 1.2TL's. The 28BSST2's output goes down to 900 wpc into 4 ohms. The X600.5 "doubles down" to 1200 wpc at 4 ohms.

    I have attached spreadsheets which compare the JC 1 to the X600.5 and to the 28BSST. Specs can be misleading if you don't know the design specifics. For example, the JC 1 has a slew rate of 130 V/usec compared to the X600.5's mere 50 V/usec. That might lead some to believe that the JC 1 is the faster, more agile and more nimble amplifier. Nelson Pass explained the X600.5's lower slew rate this way:

    "In the X600.5 the symmetric voltage gain stage will peak out at about 100 mA. We also take advantage of balanced output stages (halving the slew requirement), and last but not least, we bias the amplifiers high."
    Proud and loyal citizen of the Digital Domain and Solid State Country!
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  • EndersShadow
    EndersShadow Posts: 17,543
    edited April 2013
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    DarqueKnight wrote: »
    No, I'm not there yet. There is always something "better" around the corner.:cool:

    LOL, I agree to disagree.....

    Whats left Raife? Re-wiring your connection from your house directly to the power station :biggrin:..

    Cause thats about all I can think of.....
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
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  • DarqueKnight
    DarqueKnight Posts: 6,765
    edited April 2013
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    EndersShadow wrote: »
    LOL, I agree to disagree.....

    Whats left Raife? Re-wiring your connection from your house directly to the power station :biggrin:..

    Cause thats about all I can think of.....

    I can think of a few things:

    1. Dedicated, fully acoustically treated listening room.
    2. Dedicated transformer from the power company to isolate my house from the power grid's noise.
    3. Separate, audio grade breaker box for audio and video AC circuits.
    4. Commercial grade AC regenerators.
    5. Whole-house surge suppression.
    6. And things like this:

    x1000_5_side_by_side8x3_zps8119db06.jpg


    x1000_5_alt1__large_zps38105216.jpg

    Pass Labs X1000.5
    1000 wpc into 8 ohms.
    2000 wpc into 4 ohms.

    :cool:
    Proud and loyal citizen of the Digital Domain and Solid State Country!
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  • unc2701
    unc2701 Posts: 3,587
    edited April 2013
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    DarqueKnight wrote: »
    You can see that this has been on my mind for a while. I had narrowed my choices to the Bryston 28BSST2 and the X600.5. The 28BSST2 offered more power (1000 wpc into 8 ohms) and costs 13% less than the X600.5, but the 28BSST2 is optimized for 8 ohm speakers. I was not fully confident about its performance with my 4 ohm 1.2TL's. The 28BSST2's output goes down to 900 wpc into 4 ohms. The X600.5 "doubles down" to 1200 wpc at 4 ohms.

    They're both balanced designs, so they will both have the same issues with low impedence loads. The difference being that Bryston always under-rates their amps.
    http://www.stereophile.com/content/bryston-28b-sst-monoblock-power-amplifier-measurements

    The Pass is spec'd at 1% THD; from Stereophile's results, had you cranked the Bryson until you hit 1%, you would get 1300 watts into 8 ohms and 1800 watts into 4 ohms.

    I'm not aware of a class A/AB amplifier that truly "doubles down"; manufactures just manipulate the THD at which they report wattage to give the appearance of doubling down. The good news is that at 600 watts into 8 ohms, it'll be far better than the 1% THD reported.

    In any case, they're both beasts and I'm sure you'll get plenty of enjoyment from the Pass.
    Gallo Ref 3.1 : Bryston 4b SST : Musical fidelity CD Pre : VPI HW-19
    Gallo Ref AV, Frankengallo Ref 3, LC60i : Bryston 9b SST : Meridian 565
    Jordan JX92s : MF X-T100 : Xray v8
    Backburner:Krell KAV-300i
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  • DarqueKnight
    DarqueKnight Posts: 6,765
    edited April 2013
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    unc2701 wrote: »
    They're both balanced designs, so they will both have the same issues with low impedence loads. The difference being that Bryston always under-rates their amps.
    http://www.stereophile.com/content/bryston-28b-sst-monoblock-power-amplifier-measurements

    The Pass is spec'd at 1% THD; from Stereophile's results, had you cranked the Bryson until you hit 1%, you would get 1300 watts into 8 ohms and 1800 watts into 4 ohms.

    My understanding is that the 28BSST2 can do 1000 watts continuous into 8 ohms, but not 1800 watts continuous into 4 ohms. My understanding is that the X600.5 ratings are for continuous power at 8 and 4 ohms. The 28BSST2 manual (pg. 4) lists 900 watts continuous into 4 ohms. Regarding the Stereophile review, which I had previously read, it is important to note that:

    "Into 4 ohms, the Bryston clipped at 1800W (29.5dBW, 117.5V wall voltage), though it couldn't maintain its high power into 2 ohms, delivering 1050W (24.2dBW, 116V wall voltage)."

    The following quote is from the X600.5 manual (pg. 7):

    "The Pass Laboratories X600.5 is optimized for loads nominally rated at 4 ohms and above. You can run the amplifiers into a lower nominal impedance without difficulty, and we are not aware of a speaker on the market that presents unusual difficulty with these amplifiers."
    unc2701 wrote: »
    I'm not aware of a class A/AB amplifier that truly "doubles down"; manufactures just manipulate the THD at which they report wattage to give the appearance of doubling down. The good news is that at 600 watts into 8 ohms, it'll be far better than the 1% THD reported.

    Thank you for your insights. Pass is also known for conservative power ratings. I sent your comments to Pass Labs. I will post their response here.

    unc2701 wrote: »
    I'm sure you'll get plenty of enjoyment from the Pass.

    We'll see.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
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