Pass Labs AMP’s- What is the best Pass Amp Sound for You from past 10 years
@georgehifi , I believe the Threshold S 500's were rated to about 20% Class A; or 50 Watts. With impedance drops; as the power output doubled, the Class A output halved. There are 20 output devices per channel for a total of 40. Though, I think something like 4 devices per side were used for the then trick Stasis circuitry. |
To support 50w of Class_A in the S500 with 76v rails those heatsinks would have had to be 3 x the size. I’ve built enough Class-A’s to know how much heatsink is needed for the rail v used, some had to be water cooled. There are 20 per channel but only 18 as outputs, two are used as drivers. https://ibb.co/9h2dGW9 Cheers George |
Until recently I owned my long term McIntosh Mc 501mono blocks paired with Sonus Faber Amati Homage Speakers and the Awesome Modwright Ls 36.5DM preamp and I thought my system was good not great, on a whim I picked up the outstanding Pass Labs XA30.5 for a second Amp well this Amp blew me away the layers of detail in my system was just outstanding and control of deep Bass was much improved over my McIntosh I was so impressed I sold my McIntosh mono blocks (something I never thought I'd do) and bought a used set of Pass Labs XA100.5 mono blocks I am still running these in (they have been sitting for a year) it's sad what I was missing, I did love my McIntosh but Pass Labs XA.5 Amplifiers are in a different league, enjoy! |
"[...Interesting the int 250 doesn't get much love here. The reviews are pretty darn good....]" ReportReport |
Great thread and views. New to (higher end) hi-fi by recently getting Sonus Faber Olympica III speakers and am now looking for a Pass Labs amplifier. Any advice on which of the Pass amps - integrated or separates, would work well with these speakers? The room is large with a high ceiling. Mostly listen to jazz, blues, classical music. Cheers. |
I have had the following Pass amps in the last few years: XA-25, XA-30.8, and INT-60. The 30.8 was best, second was the INT-60. The worst by far was the XA-25. It was impressive for great recordings when listening for shorter periods, but with less than stellar recordings or longer listening sessions, it was fatiguing. I even added a tube preamp to no avail. It perhaps was too transparent. I just did not like it much. |
Happy Pi Day; I have had a few Pass amps over the years; X250.5 (circa 2007), X150.8, X250.8, XA30.5, and now INT-250; My system has been in mega churn last half of 2019, but has quieted down recently; I took a tour with some Luxman stuff, the 507Ui, 509X, and the 900 models, the M-900/C-900 combo. I let go of the 900 stuff late last year and ordered an INT-250; I have been LOVING the INT-250 and feel, for me, its just perfect....but...I moved up to a larger set of speakers, the Dynaudio Confidence 50s and have been talking to Pass about next steps-very interested in the X260.8 monos, X350.8, or perhaps XA100.8 (not a huge fan of two giant power sucking Class A monos but they probably offer best sound quality) . I came across a chance to get back into the C-900 preamp, which to me is just phenomenal; The M-900, yes is very good, but I feel there is a better match between amp/speakers with Pass horsepower. The sound is super neutral and has a natural feel across the board with Pass/Dyn; So, i’m currently using a Chord TT2 into the C-900, into the XLR input on the INT-250 and the SQ is far beyond what I had with just the TT2 into the Pass; So I have an ad on USAM for the INT-250 (bought brand new at RENO) hoping to get the 260.8’s; I loved my time with the XA-30.5; it was just pure sweet magic to my ears. The best most dimensional presentation of voices i’ve yet to hear--just very intoxicating. However the bass could be a bit flabby at times and at higher levels into the Dyns I could hear it strain a tad--but that was super loud. I remain amazed at how few watts are actually required on an RMS basis. Overall the newer 0.8 series has superb upper treble refinement and is still highly resolving; The midrange is neutral and voices sound real to me; I think the 0.8 series overall have a cleaner and clearer presentation than the 0.5 predecessors; But, speaker matching and room response will be the final arbiter on overall "tone"; I recently installed a bunch of GIK bass traps and after some frustration (they are very effective and little goes a long way) settled onto a configuration that works; With this I have discovered new levels of bass tone and definition--they were always there but the "Lens" (aka room response) was foggy; I have learned that much of my judgement on equipment and speakers was muddled and incomplete because of ill-controlled room acoustics. I strongly believe we rip through gear looking for subtle synergies, but the real cause of frustration with the sonic result (why else do we go through equipment churn?) is from a confounding room response. Back to the OP's question: I don't have a favorite I suppose; they all have positive attributes in their own way that the rest of the system pieces flush out or suppress; I kind of wish I had a rack in some back closet that could store them all, lol; Sorry for long and meandering response, just feel like writing to get my mind off the current events. Happy Listening All and Keep Clean! |
I had a First Watt J2, Pass Labs XA 30.8, and First Watt SIT-3. They were all excellent amps but, I like my SIT-3 with my Horning Eufrodite Ellipse speakers the best. They are a 4ohm and 98db efficient speaker. Which is in the SIT-3 sweet zone. I also use Coincident Frankenstein M300b's Mk.2 amps on the tube side of things. I have the best of both worlds and I'm very content! |
I just bought a Pass Labs X250.8 and am loving it. The rest of the system is an ARC Ref CD8 and ARC Ref 5se, and Sophia 2's. It has the bass weight, extension and slam I wanted (my last amp was a vintage Krell FPB 400cx - so I'm comparing my Pass to the Gold Standard here), and adds a wonderfully smooth, organic mid that is really satisfying. It's got amazing detail, and is very relaxed at the same time - a remarkable combination. Instruments and vocals are fully formed like the real thing, not flat images in space. The highs are all there with a ton of air and detail (cymbal rides and bell hits convey the tone of the cymbal beautifully [I'm a drummer]) but it's perfectly balanced in the mix, it's not distracting or forward. |
250.8 and XP22. Demo'd a 250.5 for a short while, though not with a pass pre-amp. Had the XP12 and 250.8 for a good 2.5 years, but then upgraded to the XP22. XP12 and 250.8 were very good, the XP22 took things to great, and there was a pretty clear difference. I had the XP12 and 250.8 combo on a pair of DynAudio Contour 60's, Klipsch Epic CF4's (with a few upgrades), Ohm Walsh 5000's, and Salk SS12's (current speakers that I absolutely love). I've had other speakers here on demo's. It's very rare that the XP12 and 250.8 wasn't a nice combo. Now the XP22 I've heard on the Walsh 5000's, Salk SS12's, Salk Song 3 encore's (friends), martin Logans (Friends), and a couple other demo's. It's a great combo. Great Midrange, excellent bass, and all the highs (without crazy brightness). I did have a nice Levinson here for a while, and it may have had a shade more detail on the top end, but with a little more harshness in the mids. I felt the Levinson might have been 10% or so tighter in the low end, but with not nearly the oomph. |
I talked to a couple people with pass labs amps and they both felt the XA series is 'far superior' to the X series. For those of you who have compared, is this the case? I guess it depends on how demanding the speakers are but apparently the XA series has components and designs that are closer to the XS series and thus is a better performer. Talking to pass about this they mentioned the X series may have a bit more bass control and more dynamics especially with harder to drive speakers where the XA series might have a more organic midrange and more detail. |
I am the original owner of a Threshold 4000, and had it "updated" and recapped a while back by John Soderberg. Still sounds great when being fed by a Herron Phono/LTA MicroZotl front end. I would be interested to hear if any of you Pass-aficionados have any experience in comparing the 4000 with recent Pass amps? |
I am a bit confused as to why some people believe the xa is better when often times the x series does not even leave class A to drive the speakers. assuming the needle on your x series does not move much let alone go past noon position then you are in class A if I understand my conversation with kent english at pass correctly, so if your speakers dont push the amp out of class A then essentially the x series is class A like the xa series. my 260.8 monoblocks have 33 watts of class A and with my 40.2 harbeth speaker does not leave Class A (which is surprising given face that harbeth like power and I play relatively loud) I was initially inclined to get xa60.8 monoblocks but was advised that the bigger harbeth were recommended by the distributor usa for harbeth to pair better with x series. Has anyone heard the xa60.8 and 260.8 in same system and heard a difference? I can imagine in a big room or with speakers that are very demanding |
I have an X250.8 with Sophia 2's. I'm very happy with the combination. Very natural, organic mids and highs, and excellent bottom end extension and weight. Slam is very good (but not a Krell). Outstanding, realistic 3D imaging. I think the Pass brings out what the Sophia's do well without exaggerating anything or making them fatiguing. Upstream it's an ARC Ref CD8 into an ARC Ref 5SE. The Pass works really will with that. Very happy with all of it. |
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I took an X350 home one weekend in 2002 for an audition. 19 years later- this past February I switched to the new X260.8 monos. My son has the X350 now. I’m using these amps with an ARC Ref 5SE and Thiel CS6 speakers and Purist Audio cables throughout. I can play it loud for me and the needles don’t move. I was nervous that I might feel the loss of the few watts difference from the X350 but no. It took some time for them to break in. Every time I listen now the sound stage is startlingly clear and focused. The highs are crisp and fast. That’s the best way I can describe it. |
Thanks so much for sharing your power amp journey, probably the most useful I've ever come across-especially because it compares, at least in some important ways, respectable 300B SETs like the Franks with the First Watt F4. "They have a bit of the sweetness of my 300b SET amps, but both clarity and bass control that beats out all the other amps I've auditioned on these speakers. The soundstage is expansive, imaging is precise, and there is absolutely no harshness or grain... an important quality with the accuton ceramic tweeters on the PREs. Exactly what speakers do you have? I have two F4s that I had ordered from Reno Hi-Fi years ago. My speakers I'm have custom built from a proven design are ~ 94db/m/watt but only play down to 70Hz before my powered subs take over, so I can't see even one F4 having any problem driving them in my room and listening levels. I'm very glad you also mentioned the F4's "expansive" soundstage. Would that also be so in a 3D sense? And even if I use only one F4? Also, very assuring is that you found zero "harshness or grain', as my tweeters likely be Raal ribbons. Now the big questions are what is the ??db spl/m/w of your speakers, what preamp are you using and what's the approximate output voltage usually needed to drive the F4 to make your speakers shine?
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@ajant I have Coincident Pure Reference Extreme speakers. I think they're around 92db/1w/1m (listed as 94db, but I don't believe it) and supposedly a flat 8ohm impedance. I'm sure you could get by with a single F4, mine worked fine that way... but I still believe in monoblocks for isolating right and left channels. I have tried my F4 monoblocks in a bridged design and actually preferred just using a single channel. Essentially you're doubling your power supply capacity that way. I found that there was less distortion with an increase in clarity, smoothness, and sweetness from the amps using them in that configuration. And yes, I find the amps very nicely 3-dimensional, at least as long as the source and preamp support it. That's a key decisional factor for me for every component. I've used two preamps with the F4s, a Bob Sachs 6sn7 pre and a custom Shiny Eyes EML20A DHT. The Shiny Eyes pre is a simple single stage single tube DHT design... from Radu Tarta: "This is one of the simplest one stage preamps that is using an excellent sounding DHT and extremely low distortions, second harmonic being dominant. The gain is 14dB (5x) and with a 2Vrms source will provide 10Vrms at a Zout of 375 ohms. Measured THD was 0.02% at 10Vrms output (50Vrms on the plate)." It gets plenty loud enough, but I do periodically wish I could be idling a little further down the volume control ladder. You can read more about my amps, speakers, and preamp on my Audiogon system page. I personally couldn't recommend the F4s more based on all the amp comparisons I've done with my speakers. I actually ended up rebuilding them with custom high quality parts and massively overbuilt power supplies (so now 4x the levels of a standard F4 for each channel) and they just got better and better every step of the way. That information is all outlined on the system page if you happen to care. I would only change amplifiers if I ended up with truly high efficiency speakers over 100db/w/m, or needed something with a lower damping factor. Hope that all helps. |
