Pass Labs Amp

[johniboy]

Hi!

 

I know this question is not directly linked to computer audio... but there are so many knowledgeable people contributing to this forum, I will ask anyway.

 

Does anyone have experience with an X250.5 pass labs power amplifier or a similar amplifier from the same product line?

 

Thank you!

 

[barrows]

I own a Pass X 150.5 amp. It is superb. I wish I could afford amps from the XA series, for even sweeter sound, but I need more power than the XA 30.5 can deliver. The X 150.5 sounds very, very, good and in my experience one would have to spend a lot more money (like twice as much or more) to get a better sounding amplifier. Pass amps are also conservatively rated, as such, testing has shown the 150.5 to provide over 200 watts into 8 ohms, and well over 300 watts into 4 ohms. You may not need the extra expense (and slightly higher distortion) of the 250.5.

If were planning on buying new, I would wait until after CES-Pass has been hinting about some changes to the amps. Could they possibly be replacing the output MOSFETS with the new power JFETS????

 

[Purite Audio]

I used to own a 350x, running B&w 800d's it was ok, didn't really control the bass of the speakers though, it became exceedingly hot, ended up using an ASR Emitter, which speakers are you thinking of using with the Pass?

Keith.

 

[johniboy]

Thank you for the replies! Maybe it does make sense to wait a bit for the next generation pass amps. I was also looking at the xa series but the 30.5 probably does not have sufficient power and the others are a bit too expensive.

 

I have a pair of Dynaudio C2s, which are not the most sensitive speakers (87 db) and like to be fed with more power.

 

I did hear a lot of good things about the Emitter but I just don´t need a pre-amp. I like the volume control of my Dcs Elgar and would prefer to connect it directly to a power amp. Coops, which Emitter would you recommend?

 

I heard an integrated amp from symphonic line in my system (rg10 mk4), which was really nice and therefore the rg7 (power amp) is on my short list but I wanted to look for some other alternatives. The pass amps are highly praised, not only in the US, that´s the reason I asked for opinions.

 

I like neutral, precise sound, without sounding harsh and i am not sure whether the pass amps are not a bit too "warm" for me. Also I have some nice fadel art speaker cables which have bananas on both ends and I read somewhere that with pass amps you can not use bananas??

 

Any other opinions are highly welcome!

 

[Elprior]

Hi Johniboy,

 

I've recently been listening (not owning) a pass labs full stack (xp20 + 2 * x600.5) with emmlabs source (drive + dac) and rockport speakers (mira). What an ugly sound ! The emmlabs and mira I had previously listened with a full-tube stack, and the sound was very good, so I take those for correct performers.

 

I think this was due to the fact that pass labs products take a long time to settle.

In this ecological times, I wouldn't want to buy products that take 3 days to settle, before being able to listen to music.

Like Keith said, the bass is not really good too.

Definitely the ASR emitter I is a better move, imho (a bit boomy, Keith ?).

 

Elp

 

PS : I too use dCS (purcell + delius) directly connected to amps (nuforce ref9se v2) driving revel ultima studios (first gen). Neutral, precise, very powerful, not at all sounding harsh. I can listen to volume set to 0 (in a very big room, admittedly, and output set to 2v), and feel like being there, wouahh !

 

[Purite Audio]

Jon Hi, I am not saying the pass is a bad amp, just that it didn't drive my then speakers as well as the Emitter II I used subsequently, it reallyis imprtant to think of your room the speakrand the power amp as 'one' best thing is as always try it in your room ( with some other amps ), very best,Keith.

 

[johniboy]

Jon, you are right, the final test is how it sounds in your home. But I need a short list first to be able to do that. Symphonic Line RG7 will be one of them but I need other candidates. It will be difficult enough to do the testing, because most probably there will be no dealer who has all the candidates I would like to review. A real logistical challenge! ;-) I will take a look at a smaller emitter.

 

Elp, nuforce ref9se is a class D amp, right? I never listened to this amp class. How does it compare to solid state amps? Class D exists since a couple of years now but they do not seem to have become very popular. If I remember correctly Audio Physics had a class D amp for about 2 years but discontinued them?

 

 

 

[barrows]

I have heard the ASR amps a couple of times, and they have always impressed me (driving speakers I was unfamiliar with). In the US the ASRs are about double the price of PASS models, so I would hope that they can offer some advantages. I have no problems with bass response with my speakers, but my speakers are not as demanding as big B & Ws. The Pass amps are low feedback designs, and some people believe that low feedback results in a slight drop in bass control; like I said, I do not hear this in my modest system.

I would highly recommend a home audition of the X250.5 with your Dynaudios, I suspect that this would be a pretty good match.

I have heard all the class D amps out there, and while they do some things very, very, well (bass control, midrange clarity, detail retrieval) they have a weird sound in the high frequencies that just does not work for me. If you do audition the new Nuforces, I would love to hear your impressions.

It will be interesting to see what Pass may be doing in terms of changes to the amp line for 2010. My Ayre preamp recently got the "MP" upgrade, which changed the output transistors from bipolars to JFETS, this was a very nice upgrade.

If price is not a huge concern, another solid state amp that has impressed me is Vitus, but these are way out of my league.

 

[jtwrace]

I used to own a X-250. I liked it but it just didn't have that omph that I wanted. I sold it and got 300w Class A mono blocks.

 

[barrows]

other thing. I am pretty sure the .5 upgrade to the Pass amps increased the output current delivery substantially (more power supply capacitance, and more output devices), so I think it would be misleading to believe the bass response of the pre .5 series amps would be the same as the current .5 series amps. It looks like most people replying here are referring to the X-250 and not the current X-250.5, this is an important distinction, especially when it comes to "oomph" and bass control.

 

[Elprior]

Johniboy,

 

I don't want to pollute this thread too much with NuForce, which is not the original question (just a quote), so my final words about it

 

Not exactly class D (as IcePower for instance), but a derivation with the modulation being done in the analogical domain. The best way to understand is to take a look at their site.

 

In my own system (ymmv), this works pretty well.

Everything is in place, the sound is very smooth, and you can listen at very low level with tons of details.

At very high level though, the highs tend to distort a bit (but I mean very high level).

Upgrade from V1 to V2 made the sound less "pumpy", with sweeter mids, but a slower pace (sigh).

V3 is currently shipping, and is commented to be even more tube-like than V2, with this time very low distortion in the highs (and high levels), but with even a slower pace. I'll try to listen to them very soon.

 

What can be said against solid state amps ? I haven't listened to all of them...

 

Pass Labs seems to be one of the most well reknown company.

Even so, I won't change for Pass Labs because of the warm-up time that I have already commented (when it takes at the upmost 30 minutes for the 9se v2).

 

Vitus makes very good amps, and somehow, nuforce are close, with the same kind of energy. The Vitus remains better in terms of distinction (although a bit dull), but this is definitely not the same price range.

 

Linn I was a bit disappointed with (the top of the line). Not even close to the nuforce on my system (warm-up time ?).

 

Kharma mp150 (class D, icepower) definitely not in the same league as nuforce. I won't even listen to all clones, since that is what it is.

 

Finally, the asr emitter I (haven't listened to the II), which I would glady buy instead of the nuforce.

Very very good sound, just of small complaint on bass reproduction (a bit boomy), but that was not in my system (on focus audio fs-888 instead, that I don't know otherwise).

 

Hth,

Elp

 

[manisandher]

IIRC, the Kharma amps use an early version of the Hypex UcD module, designed by Bruno Putzeys.

 

Joniboy, although I can't comment on the current Pass Labs lineup, I did own a pair of X600s for many years and still own an Aleph4 (as well as an X1 pre and a pair of XVR1 crossovers).

 

The X600s were incredibly dynamic but sounded too 'clinical' to me, pretty much regardless of speakers. Perhaps the .5 versions are better in this regard...

 

I've heard that the XAs are a mix between the Aleph and the X series - now that should be nice.

 

If I were looking for a new solid state amp though, I'd probably go for a new FirstWatt amp (the F5?[EDIT: sorry, meant the J2]) and pair it with some high-sensitivity speakers.

 

Mani.

 

[Elprior]

You're right Mani, sorry for the confusion.

So I never listened to IcePower in my system

 

Elp

 

[johniboy]

Thanks all for your help!

Right now I have a Linn 2250 poweramp. It is the weakest part of my lineup and it will not be difficult to find smth better. i also have to say that, while Linn makes some impressive digital and analog front-ends, they are not the best with amps and speakers (in my opinion and to my ears).

 

Sounds like I will have to try a Pass XA30.5. Maybe it has enough juice for me; I do not need that much oumph if I get detail, transparency and emotion. By the way, the C2s are also not known for their huge bass... Once I listened to a Dynaudio Evidence Temptation with Dynaudio pre and poweramp. Thats when I got really caught up in high-end audio. Interestingly I couldn´t hear the bass (as a separate entity) - it just sounded real.

 

If I can get my hands on an Emitter and the new version of NuForce, I will definitely look at them, too. Its always fun to try new stuff! ;-)