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Old 23rd November 2010, 05:00 PM   #71
JimM is offline JimM  United States
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Julieng: I have a pair of Thiel CS2.2 and have driven them with my PassLabs INT150 with execllent results the Thiel's like a lot of current into thier 4 ohm load and the Pass amps can provide the current.
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Old 26th November 2010, 06:02 AM   #72
nar is offline nar
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Hi Julien,

In Japan for now, leaving tomorrow very early ...
Come back to France where the weather is very cold it seems (snow)

Have you survived the arrival of the XA-30 ? I just wondered if you had time to plug it and make the usual burn-in tests ...

Forward to hear your comments. And also, did you try passive be-amp with the X amp for the bass ?

Best regards,

nAr
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Old 26th November 2010, 03:01 PM   #73
generg is offline generg  Germany
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My Thiel SCS4 run very fine with a self build Aleph 3, not the perfect resolution but a feeling of great power and dynamics, bass is working fine.......and the hot highs are minimized.
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Old 27th November 2010, 03:04 PM   #74
Apogee is offline Apogee  United States
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Originally Posted by JulienG View Post
You are right. I didn't have the experience nor that much information when I ordered the x250.5, now I understand that the bias/current capabilities are much more important for low impedance speakers such as mine. Apparently the sensitivity is closer to 88db, but even at 87db it shouldn't be a problem since I don't listen at crazy volumes and my normal listening position is under three meters away from the speakers. Isolation is bad in our building so I don't want to play too loud anyway, do not need huge dynamics (sometimes if you're close a little compression is welcome, you don't want to be adjusting the volume at the extremes...), and need controlled but not "big" bass. So my guess is that even into my speakers at medium volumes it shouldn't really leave class A too much. XA30.5 on the way, please tell me I am doing the right thing...
Greetings Julien,

Yes, I believe you've done the right thing.

I'm very anxious to hear your thoughts once you've spent time with the XA30.5.

I must disagree with Nar in that I would not mix amplifiers on the top and bottom at this time.

I would bi-wire from the amp to the speakers making sure to use decent wire, and making sure what I used for the bass is heavy gauge; that's it. I would keep it very simple to get a feel of what the amplifier is capable of. Minimizing complexity is usually a good thing in my opinion.

Please keep us updated. I look forward to your comments.

Kind regards,

Steve
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Last edited by Apogee; 27th November 2010 at 03:32 PM.
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Old 1st December 2010, 11:51 PM   #75
JulienG is offline JulienG  China
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Quote:
Originally Posted by nar View Post
Hi Julien,

In Japan for now, leaving tomorrow very early ...
Come back to France where the weather is very cold it seems (snow)

Have you survived the arrival of the XA-30 ? I just wondered if you had time to plug it and make the usual burn-in tests ...

Forward to hear your comments. And also, did you try passive be-amp with the X amp for the bass ?

Best regards,

nAr
I'm going to France now... filming a few shows and then getting married... I haven't received the XA30.5 yet, they didn't have it in HK and had to order it. Should arrive in Beijing in a few days when I'm in France... which means I'll give you guys my impressions at the end of the month.
Apogee says I shoudn't biwire and I won't, even if I wanted to Thiel speakers only have two entries...
Anyway thank you guys, I'll keep you informed!
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Old 26th December 2010, 02:10 PM   #76
JulienG is offline JulienG  China
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First impressions of the XA30.5, right out of the box, compared directly to the X250.5 : would seventeen thousand times better seem exaggerated? Not to me: much more natural, finally it's just music coming out. No more acid-like high frequencies because of the low impedance, much better bass depth and control than the X250.5, and by a wide margin! Do you believe that? I hope this can help people in the doubt to forget the myth about the X series automatically controlling the bass better than a few dozen watts of class A...
Thank you Mr Pass for pointing out to me that higher bias was important with low impedance speakers! That must be why my speakers used to work so well with the Plinius 9200 (high biased AB). Simaudio W5 was beautiful too, I guess they just have more polished highs than the Pass X series... So right now I would recommend to anyone with Thiel speakers or speakers that go down to under 3 ohms especially in the high frequencies to try the XA30.5. Better than anything I've ever tried, and definitely more than enough power ! My 87db Thiel CS2.4 suck a lot of power right now, especially since my VSE modded Sony SACD player has ridiculously low gain and my newly bought Audio Research balanced tube pre doesn't have gain settings. But even like this, even though I'm often in AB mode when I listen loudly, I'm not even close to using the power of the amp. People tend to think that so called headroom is much needed in order to feel an effortless flow of the music, well it may be true to some extent but when you use 100 W at most on the loudest peaks and have 180 W at your disposition it is more than enough. At least the 180 Watts into 4 ohms of available AB power in the XA30.5 give me so much more effortlessness than the 500 Watts in the X250.5! Just music in the air...
So this is for those with the same concerns I had: unless you have speakers under 86db and play really loud in a really big room, I suspect the XA30.5 will be well enough for your speakers, and make some smooth, effortless music for you. I think also that people tend to forget that even if your speakers use a lot of power and the XA30.5 runs AB all the time, this still is one of the best sounding AB amps in the world, I definitely still hear the exact same full bodied smooth XA series class A sound when playing loud in AB push-pull operation. Very different than the X series even while running in class AB, I suppose it is mainly because of the higher bias... And for this price it's a steal! Don't forget that for the exact same amp with just more power, XA160.5 or XA200.5 sell at prices many many times higher and are widely considered as some of the best amps on this planet!
So, we have a winner. XA30.5 gives me a big smile I haven't had for years...

Last edited by JulienG; 26th December 2010 at 02:36 PM.
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Old 26th December 2010, 05:58 PM   #77
a.wayne is offline a.wayne  United States
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Great to hear JulienG......................
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Old 26th December 2010, 06:13 PM   #78
nar is offline nar
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Originally Posted by a.wayne View Post
Great to hear JulienG......................
That's great to hear, because it comforts Mr Pass research through the years, with a simple or double cascoded/current source jfet elementary pair + AB complimentary output stage with single ended bias added - with SuperSymmetric structure e.g. full balanced amp seems to be at ease on any load, musically speaking
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Old 26th December 2010, 06:29 PM   #79
a.wayne is offline a.wayne  United States
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More info : Pass Labs XA30.5 power amplifier Specifications | Stereophile.com
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Old 14th February 2013, 04:16 PM   #80
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Hi,

I hope people don't mind me unearthing this very old thread, but it hit on a question I have been worrying over exactly--can I run my Thiel CS 2.4's with the XA-30.5/Int-30? The end of the thread is an enthusiastic yes, but I figured it was worth asking one more time--does anyone out there have any similar experiences? Reading Mr. Pass's website, the Thiel's would be just on the side of the 30.5 (as opposed to 150.5), but the Thiel's call for 100-400 watts at 4 ohm. As noted in the thread, the 30.5 can operate above its rated power level in A/B...I will stop here, as I am just an economist, not an engineer. Maybe I will figure this stuff out eventually.

I will be somewhat sad when I buy an amp; this stuff is fascinating. Great website, too.
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