...and 120WPC into 4 Ohms.. Stereophile's John Atkinson measured one and got maximums of 150 Watts into 8 Ohms at 1% THD, 240 into 4, and 380 into 2. VERY impressive!
My question--are those large outputs achieved with the amp still in Class-A biasing or does the amp fall into class-AB biasing beyond, say, 60 Watts into 8?
Here's my system recently.. Amps are PS Audio BHK600s and Pass X260.8s; speakers are SoundLab Majestic 745s.
My question--are those large outputs achieved with the amp still in Class-A biasing or does the amp fall into class-AB biasing beyond, say, 60 Watts into 8?
Here's my system recently.. Amps are PS Audio BHK600s and Pass X260.8s; speakers are SoundLab Majestic 745s.
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It operates in Class A up to 60W @8Ω, 30W @4Ω and 15W @2Ω, switching to Class B beyond that range.
from NP's article Leaving Class A:
We get a lot of questions about this. A typical email reads, “I can’t sleep at night – I keep worrying about where my amplifier stops being Class A. As I listen to my system, I think I can hear the Klunk as the special Class A part of the amplifier kicks in and out!”
We get a lot of questions about this. A typical email reads, “I can’t sleep at night – I keep worrying about where my amplifier stops being Class A. As I listen to my system, I think I can hear the Klunk as the special Class A part of the amplifier kicks in and out!”
We also have to decide what constitutes Class A, as Bob Cordell agrees that it means a significant
contribution by both halves of the push-pull circuit. Having 1% of the bias current in the "unused"
half is not much of a contribution even though it is technically in forward conduction. Often that is
called "non switching".
We rate our push pull amps pretty conservatively, so you will still see significant bias beyond the rating.
contribution by both halves of the push-pull circuit. Having 1% of the bias current in the "unused"
half is not much of a contribution even though it is technically in forward conduction. Often that is
called "non switching".
We rate our push pull amps pretty conservatively, so you will still see significant bias beyond the rating.
The 2nd carton arrived yesterdayafternoon, Monday the 14th, and since then they're breaking-in about 20 hours per weekday and will be 24 per day from Fridays 7PM thru Mondays 4PM.. They sounded quite good last nite. 🙂
Thursday afternoon makes about 40 hours on them, and they still sound very good, as in they commit no sins that I can hear.. Probably I'll start paying attention after about 1 week...160+ hours.
I believe that one reason that these 'low-power' amps sound so good to me is that I do NOT require my system to have wide dynamic range, due apparently to my damaged ears and subsequent use of hearingaids...and my hatred of rock'n'roll and its variants.
IF if if I'm thrilled with these '60s in a month, probably I'll not build a new lowboy cabinet but simply place the three amps--those currently on the bottom level--on one wide piece of 3cm granite.. I'll have to suspend the Magneplanar CC speaker (in pic above) other than by then-nonexistant lowboy, but how hard can that be? We'll see how it all goes.
Meanwhile, my long-planned trip to The Music Room...
https://tmraudio.com/
...to haul much surplus audio equipment for consignment sale will happen next week.. I've been packing cartons, sorting 'stuff', etc. for a few days already, after being cleared by my shoulder surgeon for normal duty.
I believe that one reason that these 'low-power' amps sound so good to me is that I do NOT require my system to have wide dynamic range, due apparently to my damaged ears and subsequent use of hearingaids...and my hatred of rock'n'roll and its variants.
IF if if I'm thrilled with these '60s in a month, probably I'll not build a new lowboy cabinet but simply place the three amps--those currently on the bottom level--on one wide piece of 3cm granite.. I'll have to suspend the Magneplanar CC speaker (in pic above) other than by then-nonexistant lowboy, but how hard can that be? We'll see how it all goes.
Meanwhile, my long-planned trip to The Music Room...
https://tmraudio.com/
...to haul much surplus audio equipment for consignment sale will happen next week.. I've been packing cartons, sorting 'stuff', etc. for a few days already, after being cleared by my shoulder surgeon for normal duty.
That certainly looks like doing Burn-out testing rather than Burn-in
If you don't get them out into free air soon, there will be no listening in 160 hours.....
Okay, maybe the thermal switches? in the XA60.8's will prevent that from happening - but this certainly does not improve lifetime
That certainly looks like doing Burn-out testing rather than Burn-in
If you don't get them out into free air soon, there will be no listening in 160 hours.....
Okay, maybe the thermal switches? in the XA60.8's will prevent that from happening - but this certainly does not improve lifetime
===========================
I thought of that too, but...this location is only temporary, and after hours of use, I can hold my hands on the amps for many seconds. Monday afternoon they'll have about 150 hours on them and I'll move them to the upper shelf.
One is always bound by the laws of physics. 240watts into 4 ohm class A .now that would be a monster.
Decided yesterday to keep the XA60s over the PS Audio BHK600; the former produced smoother-sounding violins while sounding higher resolning.. Have mosed the Passes to the top of the lowboy...
Having only three poweramps in the backend simplifies the siting issues, too, since the three amps will fit on one 3cm granite slab.
Having only three poweramps in the backend simplifies the siting issues, too, since the three amps will fit on one 3cm granite slab.
I have listened to PS audios reference system with the fr30s in Boulder. It teally is a Wonderful sounding system. Pass Labs .8 series is a bit more holographic, rich, the Imaging floats around a bit more. Liquid is a good way to describe it.
I prefer pass labs too. Although that is probably not a surprise as this is a pass labs forum. However, PS audio gear is no slouch.
An interesting note. The people at PS audio are gear nuts. They like to collect gear from other companies and enjoy them along with their own stuff. I spotted a pair of XA600.5's in their secondary recording studio.
Enjoy your new amplifiers! Feel free to share Somewhere listening Impressions when you get around to it!
I prefer pass labs too. Although that is probably not a surprise as this is a pass labs forum. However, PS audio gear is no slouch.
An interesting note. The people at PS audio are gear nuts. They like to collect gear from other companies and enjoy them along with their own stuff. I spotted a pair of XA600.5's in their secondary recording studio.
Enjoy your new amplifiers! Feel free to share Somewhere listening Impressions when you get around to it!