[I.Greyhound Fan]

No wonder you like them: AVA FET Valve 600R is the 2016 TAS Editors' Choice Award winner! 

Has anybody had a chance to listen to Schiit Vidar at AXPONA? Impressions? 

There is not a chance in hell that the Vidar at $699 will compete with a 600R and the DVA 700.  However, having not heard one, I would not doubt that it sounds good, as Schiitt makes some nice gear.


I will catch some flac for the above comment

[SoundSound]

Perhaps, we should have a listen first? They have been known as big “disruptors” of the market… 

[I.Greyhound Fan]

Perhaps, we should have a listen first? They have been known as big “disruptors” of the market… 

A listen for sure, but I have been disappointed with budget  priced gear claiming to best much higher priced gear for the most part.  I am sure that those mono blocks sound great for their price and they may perform above their price point.  What I have found when pairing budget gear with gear that is way above in price that the lower priced gear is the weakest link and it is exposed.  So call me a little skeptical.  Of course I could be all wrong

[RDavidson]

I 3rd the notion of trying a Pass amp. As many know here, I'm a fan and have owned several First Watt and Pass amps (and still own a couple currently). I also happen to have a pair of Monitor Audio RS6's. They've served as kind of my reference since 2007 while many other speakers have come and gone. Only Omegas have stayed, but that's another story. As I've had them so long and my budget has greatly increased over time, I've been able to try them with many amps at various price points. They are really well designed and have an amazing balance of strengths and few weaknesses. They also respond very well to equipment upgrades well beyond their price point. They're almost classics. Despite their slightly above average sensitivity rating (about 89 db) they're SUPER easy to drive because their impedance doesn't drop below 6 ohms, if I recall.
With that said, I don't agree that the XA30.5 is warmer than the XA30.8. That's just not my experience. The XA30.8 sounds more pure (very similar to a First Watt amp), but with massive bass and a bigger presentation. I guess the purity could come across as sounding more linear, but I also found the 30.8 to sound more natural and less "amp-like." The XA30.8 runs deeper into class A. As such, it also runs MUCH MUCH warmer and uses more electricity. The 30.8 can raise the average sized room temperature a couple of degrees ; The XA30.5...not so much. It runs warm, but not to the same degree as the 30.8. I really like both amps. I can definitely see how one might choose one over the other. Overall, I think the XA30.5 is a fantastic suggestion, especially for the budget. It's great sounding, built like a tank, looks great, and has first class customer support based in California. Don't worry about power. It has PLENTY of current for the RS6's. Even under demanding conditions, I bet the bias needle would barely move. Well before that point you'd probably be damaging you hearing anyway.

[SoundSound]

Dear Audiophiles! 

You know what I want to do right now? Shake hands with all of you! Thank you very kindly for all your most appreciated help, guys! 

I see a very strong support from the forum members for Pass Labs (exemplary customer service, no need to buy brand new gear to get help: Threshold T3 from the year of ~1994 was serviced!) power amplifiers, and it looks like I basically need to make a choice between XA30.5 and XA30.8.

Do you believe I have a chance to get XA30.8 (Retail $6500 after Sept. 1st, 2015) within my very limited budget of up to 3K used? I do not think so, unfortunately enough…

As @RDavidson kindly noted, “Overall, I think the XA30.5 is a fantastic suggestion, especially for the budget. It's great sounding, built like a tank, looks great, and has first class customer support based in California. Don't worry about power. It has PLENTY of current for the RS6's”.

XA30.5 it is. 

A few questions, if I may…

How reliable are these Pass Labs beasts? I would definitely prefer not to haul mine for service cross the border to the States and back! 

Any particular places you would recommend me to check for used Pass amps, please? 

And last, but not least: will XA30.5 “work nicely” with my upstream and downstream components, please? Please see the specs below for your information. 

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)
Retail $5500 (Discontinued after Sept. 1st, 2015)

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-measurements-monitor-audio-silver-6&catid=77:loudspeaker-measurements&Itemid=153

[brj]

A few quick comments...

The only issues I've either personally experienced or heard of regarding the XA30.5 were cosmetic (injured face plate or heat sinks) or related to the meter in front (I've heard of tiny spiders trying to set up shop in them, though a (very carefully aimed) blast of compressed air seems to do the trick).  I've never heard of a functional issue, though I'm hardly a definitive reference.

When I've purchased used Pass gear, I've always emailed Kent English @ Pass Labs for any repair history related to the product (based on the serial number), and he has always happily responded.

If you prefer to avoid a private party sale, you could talk to Mark @ Reno Hifi, who sells Pass factory refurbished Pass Labs gear. (I note that he has a 30.5 available at the moment...)  Prices tend to be a bit higher than the best possible private party prices, but he knows his stuff, is selling it with new factory packaging, and you'd be hard pressed to tell it from new.  I haven't purchased from him, but have come close a few times.

I don't have time just now to look at your specs in detail, but as I recall, the phase angle/impedance plot from Stereophile didn't look overly challenging.  (Where it drops to 4 ohms, the phase angle wasn't exacerbating the problem.)

[RDavidson]

Agree with brj's answer. I will add that Pass has been known for impeccable longevity. For many years they touted that they have never had an amp fail in the field. I'm assuming this means under normal circumstances/useage and doesn't account for the rare fluke....like premature part failure, which can happen to virtually any complex device. I'm not sure if they still tout this, but I would not doubt this to still be the case. And again, understand that irrespective of warranty, Pass Labs stands behind their products and will take care of you.

Preamp should be fine. It's a normal active type it looks like so voltage shouldn't be a problem. Also, the XA30.5 has pretty high input sensitivity. Input impedance is normal for an SS amp too (read, no problem). You can try passives or buffered preamps, if you ever feel like it. I'm a fan of buffered, low / no voltage gain preamps.

If I remember correctly, the RS6's stay above 6 ohms for the VAST majority of their operating range. Actually, here's what Stereophile says:
"The Monitor Audio Silver RS6's estimated voltage sensitivity was 89.5dB(B)/2.83V/m, which, if slightly below the specified 91dB, is still higher than average. Its impedance (fig.1) remains above 6 ohms for almost the entire audioband, with a minimum value of 4.5 ohms at 165Hz. As well as being usefully sensitive, the RS6 is also an easy load for the amplifier to drive." I can appreciate the measurements for the Silver 6 you've cited, BUT those are not the RS6's measurements. The Silver 6's are two series newer and it is somewhat reasonable to believe that the newer series would have improved measurements across the board, but that's simply not always the case. They may have made improvements in areas like driver technology and crossover technology, but this may not equate to better sensitivity or impedance plot. There are always design / technical tradeoffs, even with advances.

The XA30.5 will have a very easy time with the RS6's. That's a good thing, because for the first few watts the XA30.5 operates in single ended class A. Afterward it switches to push-pull class A (if I recall correctly), then class A/B. I think you'd be destroying your ears if you ever get it to go into class A/B with those speakers. The only time I got the amp to switch to class A/B was with the difficult to drive KEF LS50's I once owned.....and that was VERY loud. It wasn't during serious listening. I was intentionally trying to see if I could push the amp a bit and see if I could hear a perceivable difference as well as make the bias needle move a bit.

[timind]

How about a Primare A32? http://www.primare.net/product.asp?ProductID=45

Never heard it, but I have owned several Primare amps and liked them all.

[I.Greyhound Fan]

I have had no issues with my older Pass X250.  It is built like a tank.  But unexpected failures do occur with electronics from time to time.  On thing to consider when buying a Pass amp is heat as they run in Class A and they have huge heat sinks that get up over 115F.   My X250 can heat up my room fairly quickly if I close the french doors to my 17x17x10 room.  I live in Minnesota so it is not much of a problem during most of the year but in the summer the room can get a little warm after 1 hour.

Excellent choice if you go with the 30.5.  You will love the Class A sound.

[SoundSound]

Thank you very kindly, dear friends! 

As @brj and @RDavidson noted, it does look like XA30.5 is indeed a good fit for my modest setup. Excellent! 

A very interesting question of heat dissipation was mentioned again by @I.Greyhound Fan: “My X250 can heat up my room fairly quickly if I close the french doors to my 17x17x10 room.” Over 115F! 

Earlier @RDavidson also mentioned “The XA30.8 runs deeper into class A. As such, it also runs MUCH MUCH warmer and uses more electricity. The 30.8 can raise the average sized room temperature a couple of degrees ; The XA30.5...not so much. It runs warm, but not to the same degree as the 30.8.” 

My “cave” is only 14x14x9! Should I be concerned? Mind you, I seldom, if ever listen at concert levels… 

Not exactly sure if Primare A32 @timind mentioned works in class A… 

Have found XA30.5 in Canada (3200CAD only!). S/N D-3553. Not sure if I am correct, but the serial suggests the amp should be quite old… 

[srb]

Earlier @RDavidson also mentioned “The XA30.8 runs deeper into class A. As such, it also runs MUCH MUCH warmer and uses more electricity.

About double the idle power consumption (and heat).

Although both are 30W/60W (4Ω/8Ω) and both "Leave Class A at ~ 60 peak watts", the XA30.5 has an idle power consumption of ~ 200W and the XA30.8 ~ 375-400W (spec sheet differs slightly from webpage).

Because they're Class A, the amount of power that they dissipate as heat will be similar whether played at low or high volume.

Technically I suppose you might expect a slight decrease in room heating (but likely not noticeable) playing at higher volumes because some of that electrical energy will be converted to mechanical motion at the speaker drivers rather than 100% of the electrical energy dissipated as heat at idle.

Steve

[I.Greyhound Fan]

Heat is only an real issue if you close the doors and for prolonged listening.  My room also heats up because my BAT preamp uses 8 tubes.  Don't worry about the heat unless you don't have AC during the summer.  Enjoy the amp!  I would love to have a 30.5 but my speakers require more power.

[timind]

I didn't see the class A requirement when I suggested the Primare. Sorry.

Has no one suggested Monarchy Audio? The SM-70 pro amp. You'd want two of them to run as mono blocks but they give you fully balanced as well as class A.
Nothing against Pass Labs amps, other than their price.

[SoundSound]

Thank you all, as always! 

The difference in idle power consumption .5 vs .8 certainly explains why .8 is such a big heater. Steve, is it possible to estimate how .5 will effect my room temperature? Just give me an idea, please, if possible… 

@I.Greyhound Fan noted “I would love to have a 30.5 but my speakers require more power.” Are you referring to Magnepan Magneplanar 1.6? Could you please let me know what their averaged sensitivity is? It must be pretty low, if you need X.250, I would guess… 

“Nothing against Pass Labs amps, other than their price. ” - cannot agree with you more, @timind! 

[I.Greyhound Fan]

Yes, I have the Magnepan 1.6's.  The 30.5 amp will drive them just fine, but on certain music, I will loose some of the dynamics.  The maggies like current and power.  Having high current and headroom makes a difference.

Here is a discussion from another forum about how much power do you need-


"Very interesting. I just used an amplifier gain calculator to see how much power I need for 10 and 20db headroom at an spl of 80db at 12 feet listening area from the speakers. For my Magnepans with a sensitivity of 86db I need 33 watts for 10db headroom and 336 watts for 20db headroom. I am really appreciating the fact that my Pass amp is 500wpc and can give instantaneous peaks of over 3 times that.

The link for the spread sheet is below

https://geoffthegreygeek.com/calculator-amp-speaker-spl/

Here is food for thought. Using the same calculator as above in my previous post. If I increase the spl to 85db then I need 106 watts for 10db headroom, 336 watts for 15db and 1,063 watts for 20db. And I do most of my listening between 75 and 90 db.

You can see why cheap speakers like the Elac B5's that have a sensitivity of 85db really sound better with high powered, high quality amps. Andrew Jones recommend at least 100wpc to get the most out of them. They are budget speakers at $220pr but need a not so budget amp to make them sing.  When the Elacs  debuted at the Newport audio show a few years ago, higher power Bel Canto amps where used and the speakers blew people away."

Here is a nice video discussing power and headroom-

https://youtu.be/itKqSWH07_Y

[srb]

The difference in idle power consumption .5 vs .8 certainly explains why .8 is such a big heater. Steve, is it possible to estimate how .5 will effect my room temperature? Just give me an idea, please, if possible… 

The heat that the Pass Labs XA30.5 would produce at idle would be equivalent to much higher power Class AB amplifiers.  For example, looking at a few Bryston Class AB amplifier examples:

Amplifier        W/ch @ 8Ω      W/ch @ 4Ω      Watts @ Idle
-----------------------------------------------------------
Bryston 2.5B³      135W           180W             40W
Bryston 4B³        300W           500W             70W
Bryston 14B³       600W           900W            170W
 
For these Class AB amplifiers, they will produce more heat when driven with a signal, but because much of music consists of peaks, some that may only last milliseconds (rather than continuous RMS power), it's kind of difficult to calculate and predict how much additional heat would be produced at a particular volume and type of program material.

But for your Class A XA30.5, you can pretty much count on it consuming ~ 200W continuously, varying only slightly between idle and max loudness level.  Each watt dissipated as heat produces approximately 3.41 BTU/hr, so 200W would produce ~ 680 BTU/hr.

I'm sure one could calculate the rise in room temperature given the room volume, ambient air temperature, relative humidity and R-Factors, but I would have to look up those formulas or calculators! 

Steve

[brj]

The 200W at idle value is correct, but note that the standby current draw for the XA30.5 is only about 15W.  (Per a 2014 email I have from Pass Labs.)

Note that 30W is the nominal rating for class A operation, but it is not the maximum power of the amp.  See the measurements section of the Stereophile review for more info.  (They estimate 153W max.)

The "D-" notation likely indicates a Pass demo unit.  You could always email Pass and ask for any service history.

[srb]

The 200W at idle value is correct, but note that the standby current draw for the XA30.5 is only about 15W.

Of course that's only when one remembers to put the amp in the low-power "Standby" mode in between listening sessions. Otherwise during normal "On" operation, whether a source is playing or not, low or high volume, it will have close to the 200W power consumption.

That's just the price of Class A admission, like tube amps, but generally without the maintenance, adjustment or parts replacement.

Steve

[RDavidson]

Yeah. It depends A LOT on room size. In a smaller space, one might notice the XA30.5's warmth a little bit. When I had it, I don't remember the exact measurements of my room (I've moved since then), but I definitely wouldn't consider the room to be large. I didn't have high ceilings or anything like that either. If it raised the ambient room temperature, it didn't do so any more than maybe a 2nd person in the room would (due to body heat). The XA30.5 was never more than warm to the touch, not hot. It sat on an amp stand, so it had plenty of breathing room. The XA30.8 I also owned (and used in the same room) was another story. It is much larger and heavier than the XA30.5 and biased more deeply into class A. It also produced MUCH more heat. I could definitely feel heat radiating from it much moreso than the XA30.5 when standing within a foot of it. I worked from home so I listened to my system all day. Over the course of the day, the XA30.8 definitely contributed to a higher ambient room temperature. The XA30.5 produced negligible heat in comparison. If you don't listen all day and/or don't have a very small listening room, heat shouldn't be a problem......unless you live in the desert with no air conditioning.

[brj]

Of course that's only when one remembers to put the amp in the low-power "Standby" mode in between listening sessions. Otherwise during normal "On" operation, whether a source is playing or not, low or high volume, it will have close to the 200W power consumption.

Thus the reason I use the 12V trigger inputs on mine, driven from my pre-amp.  One click of the remote and the entire system fires up or shuts down.  Very handy!

(XA30.5 trigger draw is about 7 mA.)