Has anyone compared the new Pass XA-30.5 stereo amp to the XA-60.5 mono amps? Interested to hear your impressions. I am considering one (or two) these for use with my ML Vantage speakers. Thanks.
I would imagine it would tend to exceed its rated power on peaks, which can happen often. Is it necessarily a bad thing that the meter moves, or is that to be expected with music dynamics and nothing to worry about if everything sound fine?
So long as the amp output is not exceeding the bias point (in Class A operation) the staff does not move.
Above bias point, the XA.5 amps will source something above rated wattage (they have about 4 dB headroom) and at that point the staff will swing right.
At that point the amp is still in Class A to the rated wattage, but above rated wattage it's A/B. This would be the classic A-A/B operation.
Despite the marketing hype, I believe it's not at all uncommon for some supposedly "pure class A" amps to drop into class AB at some point. Perhaps due to volume demands, perhaps due to impedance load, perhaps it can't draw enough power from the wall, perhaps it can't dissipate the heat and perhaps because the manufacturer is exagerating it's products capabilites. I think I would prefer an amp to slide into class AB rather than choke on class A and run out of steam or worse yet damage my speakers. This might partialy explain why some might choose a high powered Class A A/B amp with their particular speakers.
AFAIK there is no reason to think that any competently designed class a amp sliding into ab will damage speakers. The amount of class a delivered depends upon the bias current. Read Nelson Pass's paper on the subject on his web site. For high output solid state amps the inherent inefficiency of the design, however, requires huge power supplies, lots of heat production and large heavy heat sinks. Any manufacturer of a high output solid state " pure class a " amp which does not exhibit these characteristics is indeed exaggerating its capabilities. Reasons to choose ab over pure a include the desire for a small cool energy efficient amp or the need for very high output ( >500 watts) which is not very practical to achieve using class a. - Jim
Aldavis, I'm not sure if your responding to my post or not. If so, I don't believe that I suggested that a Class A amp sliding into class AB would damage speakers. What I was suggesting is that over driving an amp could damage speakers.
Aldavis, it might be argued that class A amps might be more prone to clipping than class AB amps in that it's easier and less expensive to provide the neccessary power to avoid clipping with class AB than with class A operation. But, honestly, this is just an academic argument.
It appears that a few people on this board are looking for non-commercial bias and honest opinion about how to choose a Pass amplifier. I would suggest that you review messages previously written about Pass XA.5 and X.5 series on this board, find ways to actually audition the amp. before consider buying, and call Pass Lab to get their advice on what amp to get given your existing stereo equipment. I did have to do my homework before buying anything. My few observations and some common sense are that: (1) People who are happy with XA30.5 tend to have smaller speakers; (2) Pass Lab personnel themselves when called upon are too proud to not give you what's right as opposed to what's profitable to them; (3) Class A amplifiers will heat up and will require some warming up time if you want good sound, but at least the XA60.5 of mine don't burn your hand like some other amp. would have; (4) All amp. regarding classification will go into clipping if you drive them that hard, but why would anybody want an amp. under-rated for the rest of their equipment? I can only tell you that the XA60.5 can certainly run enough full-size speakers, along with previously mentioned perks. As to the XA30.5, you must do your own homework, and especially don't just listen to anybody.
Mozvz, I responded earlier when you asked about the CJ ACT 2s synergy with the Pass. In a word, wonderful.
With the 100.5's on the Maggies now, I moved the 30.5 into my home office as an experiment. I've had the Cain and Cain Super Abbys in there for several years now and always got the best out of them with tube amps, especially SET's. The Abbys are a single driver/no crossover/fostex kind of speaker. Solid state made them sound hard and actually lose bass. Pass Labs and Mark at Renohifi both thought the 30.5 would pair nicely. I didn't think so. I was wrong. I'm listening to them now as I type. In three words: beautiful, relaxed and detailed. The XA30.5 is really a sweet amp.
Based on what you've said so far, I think you would be very happy with it.
Couple of technical points:
When switched on, it draws a little less than 200 watts from the wall. It does not heat up my office.
In standby, it draws just a few. Standby generates no heat but keeps the caps charged so warm up is much faster.
Your CJ has a 12v trigger that can be wired to the Pass's trigger. Turning the CJ on turns the Pass on with no thumps or pops, always a concern with tube preamps.
Mozvz, I responded earlier when you asked about the CJ ACT 2s synergy with the Pass. In a word, wonderful.
With the 100.5's on the Maggies now, I moved the 30.5 into my home office as an experiment. I've had the Cain and Cain Super Abbys in there for several years now and always got the best out of them with tube amps, especially SET's. The Abbys are a single driver/no crossover/fostex kind of speaker. Solid state made them sound hard and actually lose bass. Pass Labs and Mark at Renohifi both thought the 30.5 would pair nicely. I didn't think so. I was wrong. I'm listening to them now as I type. In three words: beautiful, relaxed and detailed. The XA30.5 is really a sweet amp.
Based on what you've said so far, I think you would be very happy with it.
Onemug,
Thank you for the updated information. I am still sifting through the choices with different scenarios in an equipment change/s.
It's also good to know the single ended connections are not any different then the balanced if I keep my CJ Act 2. Thanks Tvad..
Understood on your correction comment about the single ended and balanced having MINIMAL differences. I was NOT trying to take your words and place them in a misconstrued context as it came across in my post. Apology extend.
My earlier comment about sound superiority when compared the XA60.5 against a Stereophile Class A amplifier was based on using single-ended connection. My preamp is also in the Stereophile Class A category. Its manufacturer has a radical viewpoint that balanced connection does not make a difference in light of their well crafted circuitry. So back then there was that lingering thought about perhaps my preamp could be eclipsed by an different preamp of equivalent pricing but with balanced connection. I am known to be picky and difficult on just about anything, even as my preamp sounds pretty good and is well respected by enough professional reviewers. Yet after getting the pair of XA60.5 and am so surprised at their performance, I have resigned my concern.
The point here is more about Class A amplifier than about Pass Lab. I just dive right into Pass because they are the measuring stick and the bridging gap when people attempt to compare solid state amplifiers to tube amplifiers, with each category having its own strengths. But I would think a few upper-end Class A amplifiers beside Pass could somewhat portray what I am talking about.
Unsound you are correct in theory. The good news is that most companies which bother to produce such unwieldy beasts also care more than usual about quality because these are not produced for average audiophiles but for real old school die hards who don't care about size, heat, looks, efficiency or the latest " review". Spatine there are many well executed pure class a designs even though I admire Nelson Pass designs and have enjoyed talking to him from time to time about all things audio. - Jim
I must bow to the respected Audiogoners that have personal experience with the Pass amps, but, I was under the impression that the special design traits of the Pass amps benefit even more so from balanced use than is typicaly the case with other amplifiers.
I'm normally running Accuphase DP-67, C-275 and Krell FPB 300CX on my Vienna Acoustics The Music. My goal is to get some more body voices - the bass with the Krell is fine ;-)
I have tried Pass XA30.5 in my system and I especially like the midrange and the involvment. What I don't like is a rather slow and to heavy bass. The speakers are 4 Ohms and sensitivity 91 db. They have three 9 inch woofers pr. side.
Can anyone comment on if XA60.5 would solve the issues I have with the XA30.5? It's bigger amp but I have read here on Audiogon that the sound is very similar - they just give a possibility to play louder... (?)
Soren, I have the XA100.5. I used to have the XA160. In my system, Eggleston speakers 87dB/6ohm, the 160s were a little slow/heavy in the bass as you describe. The XA100.5 has much faster, more articulate and defined bass and are better balanced overall. Great control over the woofers. The mids on voice and strings are exceptionally involving - lots of body and presence. I have not heard the XA30.5 or XA60.5. Matching a pre to Pass amps is very important. I auditioned a very well regarded tube preamp which sounded terrible in the bass region with my amps but great in other systems.
Soren, 50 ohms is great. What brand and how long are your ic's to the Pass? Is the needle on the Pass moving when you are experiencing the flab? My 30.5 had more articulate bass on my Maggie 3.6 than my previous McIntosh 1000 watt monoblocks (as long as the needle wasn't moving). Going to Pass's 100.5 was a noticable improvement in bass. I haven't heard the 60.5. Twice the power would only give you 3db more loudness BUT that plus each channel having its own power supply would give your more control. Maybe not enough for your taste or speakers.
XA power is expensive. Have you thought of trying one of the X.5 series?
Hi, could someone please describe the sound of the XA30.5? I heard it recently, and was wondering if my impressions were close to what you are hearing. Thanks.
Well, the XA30.5 is an excellent amp. I'm sure. However a small amp. will always have difficulties controlling large areas of woofer - like the VA The Music has. The damping factor is 150 which ok but not extremely high.
"The Music" has the possibility of adjusting the bass in a few steps. When i reduce the bass the result becomes more in the right ball part ;-). Rooms are smaller here in Europe so room gain is a factor.
The IC's are Audence AU24. Balanced all the way. Speaker wires are Kimber 8TC.
When I'm playing marginally loud the needle moves a bit. It does not cross the vertical line, but is moves. Maybe the XA60.5 would be the right choice in my case;-). The XA100.5 are too expensive for me.
Chashas 1, I have written a fairly extensive review of the XA100.5 which you should be able to click to next to my username. I don't know how to create a link, sorry. It is very similar to Tvad's desciption of the XA30.5 above, which I have not heard.
For bass detail and speed, consider these determinants:
1) Powercords, particularly on your source components. 2) Amplifier power. Your woofer may have different needs compared to the rest of your speaker depending upon size, #, and crossover design. 3) Interconnects and speaker cables. 4) Room interactions. New components often require speaker position changes, even if you did not change the speaker.
Bass is inherently slow. Large waves in an accoustic hall coming from an acoustic resonating instrument should convey some ambiance. The exception might be when the percussionist dampens the instrument after striking, and the sound should recover fairly quickly. Electric bass is not always natural. Some amplifiers convey an illusion of fast bass through the midrange. I think some people are looking for a type of bass from their system that does not exist. Anyway, the main point is to review the entire system to achieve the sound you desire.
Dear Rtnl - I'm basing my impression of the XA30.5 from the outset that the only thing I change is the power amplifier from the normal situation (Krrel FPB300X) to a new situation (Pass XA30.5). The rest of the equipment, romm etc. is unchanged. Krell are famous for bass control, so its not supprising that other amps have other traids.
By the way, I use Exactpower EP15A on cd and preamplifier.
Various speakers, Tvad, with all pass gear. and it was their wiring. as i said, beautiful voices, especially say like a frank sintra record, then, you play something that needs to boogie, and it couldn't do it. You nailed it when you said no glare, smooth as anything, yet that's all it could do. I've heard the phono stage in other systems, wonderful. I'd buy it. the other stuff, no way. A real eye-opener, to be sure.
nothing fancy, some regas, some others, all can time normally in the same room, with various other gear. I kept thinking the gear wasn't getting it's due, yet everytime something else replaced it the system boogied again. I could see where the amps would be a great mate with ultra revealing speakers, at least for the mid/uppers. The low end I couldn't understand at all. It was big, to be sure, but sluggish.
Was it the newest phono stage you've heard? I can't remember the model, I think retail is $3800-4k?
Anyway, not to slag the gear at all, for certain ears or certain gear it might be just the thing. But I've got my suspicions.
You read the articles, the reviews, you know the company history, without hearing it you love everything about it, and then you hear it. I'm finding this to be true about a lot of gear lately. Too bad.
RmRobinson1957, Although haven't listened to Krell I believe in Krell's excellent handling of the bass given the number of acolations they receive. It might come down to your expectation for the total package, from top to bottom of the frequency range. As for me, I can tell you that I have not heard of any Class AB amp. coming near to realism that a Class A amp can, such as my XA60.5. Elsewhere in this thread I already described what that means. As to the bass itself, my speakers have their own powered subwoofers but I don't crank up their volume because too much bass would cloud out everything else. Leaving the sound to its natural setting, I have no problem at all getting distinctive bass that pound the ground when the music calls for it. As to comment about preamp, mine is the Bryston SP2 playing music on the 2-channel bypass mode. Bryston is known for bass. Perhaps that helps; perhaps it doesn't make a difference to the Pass XA60.5.
Tvad, what speakers are you using with your pass amp? I remember 93db somewhere, that's all i can recall. Still just trying to sort all this out in my head.
Hello Tvad, These pairs has dynaudio esoter tweetors? or is esotec? I need your email address to take some suggestion of speakers for my xa30.5. Thanks.
With all due respect, I do not understand why one would use efficient, tube-friendly speakers and then use a solid state amp. There are a number of reliable and easy tube amps out there (ie. BAT). Solid state should be for inefficient speakers (4 ohm and less, 90db and below) that have a different set of sonic priorities.
Silverline speakers are voiced with Pass Labs amplification
Wow. Those are nice. Very nice. What a great combination and the Silverline's look great in maple too. You really should put up a virtual system so we can all drool over it! ;-)
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