2. amps-preamps
  3. 129597-97719

Pass Labs XA30.5 in my system?

Dear Audiophiles!

I am looking for a solid-state class A power amplifier with balanced circuit topology to replace Acurus in my modest Hi-Fi setup:
 
Mac mini (USB3 output) ->
Singxer SU-1 ->
Yggdrasil DAC (AES/EBU XLR input) ->
Primare PRE30 preamplifier (AES/EBU XLR input) ->
Acurus A250 power amplifier (RCA input) ->
Monitor Audio RS-6
 
I am currently considering Pass Labs XA30.5 and am wondering if it will “work nicely” with my upstream and downstream components.

Any info/advice is very much appreciated. Please chime in!

Please see the specs below for your consideration.

Pass Labs XA30.5

Type: Solid-state stereo amplifier
Power Output: 30 wpc into 8 Ohm, 60 wpc into 4 Ohm (both 14.8dbW)
Power Consumption (Watts): 238
Temperature (deg C.): 53
Voltage Gain: 26 dB
Input Sensitivity: 0.77 V at 26db gain
Frequency Response: 1.5Hz–100kHz, –3db at 1.5Hz, –2db at 100kHz
Signal/noise: 150db at full power (I cannot believe this is not a misprint!)
Distortion: 0.01% at 3 watts, 0.1% at 30 watts (measured at 1 kHz)
Input Impedance: 30 kOhm balanced, 15 kOhm unbalanced
Damping Factor: 150 for an 8 Ohm nominal load
Maximum Output Current: 20 Ampere
Maximum Output Voltage: ±35 Volts
Output Noise: 150 microvolt unweighted 20 Hz - 20 kHz
DC Offset: <50 mV
Slew rate: ±50 V/µs
Dimensions: 19" (485mm) W by 7" (180mm) H by 19" (485mm) D
Weight: 62 lbs (28kg)
Shipping weight: 75 lbs (34kg)

Primare PRE30 Preamplifier

Balanced inputs          560mV
Line inputs                   280mV
Sensitivity adjustment    -20dB to +20dB
Tape outputs               280mV
Gain                            16dB
Frequency response    DC to 100kHz ± 0.1dB
THD                             <0.01%
Signal-to-noise ratio    -118dB
Crosstalk                      -113dB
Mains                            100/115/230V
Dimensions (WxDxH)    430 x 410 x 100mm
Weight                           9.5kg

Monitor Audio RS6

Frequency Response: 38 Hz - 30 KHz
Sensitivity (1W@1M):   91 dB
Nominal Impedance:     6 Ohms
Power Handling (RMS): 120 W
Recommended Amplifier Requirements (RMS): 40 - 120 W
Tweeter Crossover Frequency: 3 KHz
Drive Unit Compliment: 1 x 6” C-CAM® Bass, 1 x 6” C-CAM® Bass Mid-range. 1 x 1” gold dome C-CAM® tweeter.
Cabinet Design: Balanced velocity twin reflex ported
Product External Dimensions: (H x W x D) 850 x 185 x 250 mm
Plinth Dimensions: (H x W x D): 25 x 255 x 305 mm
Individual Weight: 18 Kg

N.B. Impedance varies with frequency and goes to as low as 4 Ohms and as high as 16 Ohms. And, most importantly,“real” sensitivity is much lower than “nominal”: 87.40dB (averaged 300Hz-3kHz, 2.83V/1m)!
Measurements taken in the anechoic chamber at Canada's National Research Council can be found through this link:
http://www.soundstagenetwork.com/index.php?option=com_content&view=article&id=1221:nrc-measu...

hardball

Showing 9 responses by hardball

hardball OP
9 posts
 
Thank you very kindly Karl!

It is VERY important for me to learn from a Guru my components are compatible with XA30.5. Quite frankly, I was a bit worried my speakers with their "real” sensitivity of only 87.40 dB, 1 meter/2.83 volt input (averaged over 300Hz-3kHz band) are not a good match...

Could you please comment on how hot the XA30.5 gets during prolonged listening sessions? Would you recommend using external forced air cooling (desk fan, e.g.)? My "cave" is only about 14x14x9 and I am concerned about it being overheated... I know, I know it is a silly one, but please give me some pointers here!

hardball OP
9 posts
 
Thank you all very kindly!

I can only dream of Ayon Titan... @4hannons, would you agree XA30.5 (much less powerful...) is also capable of driving RS-6 nicely?

@steakster, do I understand you correctly there is no need in external forced air cooling (desk fan, e.g.) for XA30.5?

You also noted "There are many high quality Class A/B amps that don't generate as much heat.   They put out Class A for the first several watts - which is fine for most listening." Could you please give me a few examples of such balanced (end-to-end) power amps?

@timlub, could you please explain what you mean by "sliding bias Class A" in case of XA30.5? I think I have seen in one your posts the headroom of XA30.5 is 4dB. Could you please confirm if this is correct?

I believe we have a consensus XA30.5 will drive RS-6 comfortably. Are you guys in agreement PRE30 will also "work nicely" with XA30.5?

What balanced interconnects would you recommend for my setup, please?

Do you believe the stock power cable is adequate?

My budget is rather tight, hence all the bugging... Sorry guys and thank you!

hardball OP
9 posts
 
Thank you ALL very kindly!

Sorry to bug you again... Could somebody please comment on the XA30.5 headroom? 

From Stereophile's measurements: "Ostensibly a 30Wpc class-A design, its measured performance reveals that it can actually deliver clipping-free peaks 6dB higher in power..."

Not sure if I understand this correctly, but does it mean the XA30.5 has a headroom of 6dB?! For example, MC452 has 1.8dB only...

@jaybe noted "I have this amp, wonderful, hope to soon move to the .8 series." EXTREMELY important: could you please give me your considerations? XA30.5 - Stereophile Recommended in 2015...

@karl_desch Are you referring to Canare L-4E6S Star Quad Balanced Audio Cable, please? I can order this XLR from Blue Jeans Cable.

Do I understand correctly you guys believe the XA30.5' stock power cable is adequate?

And last but not least... What do you guys believe would be a fair price for XA30.5 in excellent condition nowdays?


hardball OP
9 posts
 
Thank you guys!

@cal3713 I understand if XA30.5 can happily drive speakers with 87dB/2.83V/m Sensitivity, and Recommended power of 100–400W, I should have no problems with my Monitor Audio RS6. Most reassuring!

"Left the amp on 24 hrs a day..." in standby mode, I presume?

@karl_desch I have just checked Reno HiFi, and found they have XA30.5 with the following description:
"Used, Excellent condition, about two years old, one year transferable factory warranty, all factory accessories, new factory double-boxing, Satisfaction Guaranteed. S/N 28934. $3295. " Would you consider this to be a fair price, please?

What amp stand would you recommend for XA30.5, please? I have just realized my 17" audio stand is too small for the "monster"!



hardball OP
9 posts
 
Thank you very much @cal3713 ! For me it is a huge difference: $3300 at Reno and about $2700 at US Audio Mart. My problem is that not many sellers are willing to ship to Canada...

Could you please give me your suggestions on solid-state  power amplifiers with balanced circuit topology biased in such way that they do operate in class A for the first 20W - 30W? Oh, and I would prefer to stay up to 3K used...

I was considering the Son of Ampzilla II stereo power amplifier (http://www.sst.audio/son-of-ampzilla), but in this design Class A bias extends to 10W only (http://www.6moons.com/audioreviews2/sst/2.html).
hardball OP
9 posts
 
Thank you very kindly @wolf_garcia !

My "cave" is only about 14x14x9 and I am concerned about it being overheated. Hence, requirement for a SS amp.
Is there such a thing as fully balanced Tube power amp within my price range? How often is it required to change tubes, please? I would guess, every 2000 - 3000 hours or so? Some of them are made in Russia. How is it even possible to find those in case of necessity?! 

Found one XA30.5 for sale at 3.3K (ouch...). What questions regarding this amp would you recommend me to ask the seller, please? I have no experience with class A gear...
hardball OP
9 posts
 
Thank you very kindly @wolf_garcia !

This is totally unexpected: "... millions of guitar amps out there use FAR more tubes than hifi ever will..."! I must confess I had no idea tubes are still in use by musicians, i.e. professionals who can obviously hear the difference and did choose tube-based over SS gear! This is truly astonishing...

Could you please give me a few examples of tube-based power amps working in class A to drive my Monitor Audio RS6? Are they also end-to-end balanced?

If I go tubes with power amp, should I also switch to a tubed preamp as well?

Frankly, I still cannot understand how it is even possible a tube amp dissipating less heat than an SS-only design...

Checked your Sonist Recital 3 speakers: they are work of art!
hardball OP
9 posts
 
Thank you very kindly @wolf_garcia !

I never believed tubes can be superior to transistors in Hi-Fi realm because they are "prehistoric", "archaic", etc. You name it... A friend learned I am on the market for a quality power amp, and was kind enough to bring his PrimaLuna ProLogue Premium stereo power amplifier over. I must confess this amp totally annihilated my Acurus A250: I have never heard my Monitor Audio RS6 giving such punchy, tight, well-articulated bass. Piano and vocals did really come to life as well. I was just moved into another level of realism with this amp. Am I imagining things or it is really in correlation with what you found moving from SS power to tube-based, @wolf_garcia ?

hardball OP
9 posts
 
You know, @wolf_garcia , it is good to learn I am not going crazy hallucinating: it is a huge relief to hear from you I am not the only one who was just amazed with the sound transformation when switched from SS to Tube! 
With your years of experience working with tubes you must really know what is out there, and I would appreciate it very much indeed if you could please name some reputable manufacturers of tubed amps.  
I mean in addition to PrimaLuna, Atma-Sphere (way too expensive...), and Jolida you have already told me about.
I have discovered a company named Ayon. Looks like they make excellent amps, but, again, way too expensive for me: their entry level integrated amp, Scorpio (0dB negative feedback!), is for sale at $3550...
More to discover