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What is the best power amp to driver these speakers? Solid state or tube?=============================
The following reported with good results
Pass Labs X250.5
Mark Levinson No.23.5
Krell KSA 250
Bryston 7BST mono blocks
McCormack 3.0Bi-Amp
======
Leo's setup
Plinius SA102 - 125W Class A
Cary V12 - 50W Class A/Triode
The setup sounds very very nice.Class D
=====
Leo's setup
Crown XLS2502 - not transparent enough, some low level details are missing.
Edits: 11/14/24 11/14/24 11/14/24 11/14/24 11/14/24 11/17/24 11/17/24 11/17/24 11/20/24 11/23/24Follow Ups:
- regarding the Bryston 7BST mono blocksRun, run away! Don't look back! I had a pair of these powerful but lean, clean, clinical, and analytical monoblocks in my system back in 2017. In fact I had the 'much improved' 7BSST2 pair. They didn't have the harsh ear bleed sound that earlier Brystons were known for but unfortunately they weren't for me.
I was not a fan of my hefty 7BSST2 monoblocks and after trying to make them sound "musical" with various tube preamps I finally ended up selling them.
ARC LS-25mkII tube preamp driving the Brystons
Aesthetix Calypso tube preamp driving the Brystons
The Aesthetix preamp was much better than the ARC but even after much tube rolling I gave up
on trying to force the Brystons to sound better. As a side note, the Aesthetix sounded like a tube
preamp. The ARC was more solid-state like to my ears.
Edits: 11/20/24 11/20/24 11/20/24
What I learnt is that bi-amp is much easier to achieve my goal than a single amp.
Requires more amps, possibly a cross-over, gain matching so the levels are right. I went in the other direction. A single all-in-one Streamer / Dac / Preamp driving a compact and cool running Class D stereo amp.
But I do love your Cary V12. The AES/Cary SixPac monoblocks were very similar in design. I thought those were the ultimate high-value bang for the buck tube amps back in the day. A pair of less expensive SixPacs easily outperformed my iconic CJ Premier 11a.
class D + class AB will not work.
Pass Labs X350 > Mark Levinson 336 > Bryston 7B ST > Crown XLS2502 bridged.
Edits: 11/19/24
You might also consider a hybrid amp.
The Plinius amp is one of the better sounding SS amps I have heard. It has some actual richness to the sound without sounding dark, like most "tube like" SS amps sound.
A good PP triode amp like the CAT JL2 Signature would also have the grunt to work with the B&W speakers.
That said, you are better off getting easy to drive speakers and a better sounding electronics.
Which Plinius amp did you hear? I remember some of their hefty Class A / AB designs with the toggle switch to choose bias mode. My biggest concern with these older amps after all these years would be the accelerated internal component wear due to extreme heat - especially so in hot running Class A gear.
I've given up on my more demanding Thiel speakers for now instead favoring my Tannoys that sound great even with lower power amplification. The Thiels were outstanding with high power tube amplification like the Manley Neo-Classic 250 monoblocks but I've gotten away from huge, heavy, and hot running electronics in the past several years.
It is the Plinius SA102. A friend of mine has one. It is one of the very few pure SS amps that I can listen to for a long time without issues.
It has a toggle on the front that allows it to be switched to Class AB but sounds oh so much better in Class A. It runs very warm...almost too hot to touch and stays that way regardless of music playing or not, so it is true Class A, not a sliding bias design.
Thanks for the SA-102 info.Here's an interesting twist on Class A with sliding bias or what Krell called Sustained Plateau Bias. I don't think these are exactly the same thing.
When the Krell stepped into Class A operation it was truly Class A for a sustained period of time if the music was playing. It was a 'step function'. In other words it wasn't a gradual 'slide' into Class A.
Here's how I know.
I had the sweet sounding 'baby Krell' KSA-50S that put out a modest 50-WPC. It ran warm and drew a typical amount of power from the AC mains (about 100-Watts) until the music started to play. It quickly stepped into Class A and I measured a constant 400-Watts or so of power consumption from the AC mains. If I played the music even louder the amp would step up to another level drawing a constant 800-Watts from the AC mains. This was from a 50-WPC amp mind you and consistent with Class A design that draws a huge amount of AC power for the relative tiny amount of audio power output.
As the music played the heatsinks got very hot. When the music stopped dead silent the amp remained biased in Class A for several seconds until it stepped down. I measured the same 800-Watts of AC power draw for a good 20 seconds or more with no music playing. I guess that might be the "Sustained Plateau" part of Krell's "Sustained Plateau Bias" design. The KSA-50S was a wonderful sounding amp.... much better than the "more powerful" KSA-250 that I tried.
I thought it was a clever design, all controlled by a microprocessor. The amp ran true Class A so long as the music was playing but came out of Class A if there was no music for 20 seconds or so allowing me to keep the amp powered ON all day w/o it drawing a constant 800-Watts and acting like an electric room heater.
This could be thought of as being the opposite of some Class AB amps that claim to operate in Class A for a few small Watts before transitioning into higher power AB. The Krell ran Class A and went MORE into Class A as you played louder.
My other Class A amp was pretty straight forward. The Pass Labs Aleph 3 ran 30-WPC and drew a constant 250-Watts from the AC mains regardless. To be honest the Krell was the better sounding amp in my system. It had Class A sweetness and enough oomph to really bring my speakers to life. The Aleph 3 was smooth but very polite and dynamically challenged.
Edits: 11/21/24
i have heard several of these earlier Krells, including the even earlier true Class A models; the KSA 50 and the KSA 100. I have also heard the early Classe Audio true Class A amps like the DR3. These all sounded pretty good but not amazing.
The Plinius SA102 I think probably sounds better than these amps, although I haven't heard them side-by-side.
The best sounding amp I ever owned that had a transistor output stage was the NAT Symbiosis SE. It was a hybrid (tube input and driver) but it had a single huge transistor on the output stage. So, it was single ended hybrid and that output transistor was attached to a huge vertical standing heatsink and had a second transistor on an equally large heatsink for voltage regulation of the output stage...Crazy design and consummed over 800 watts continuously to put out 100 watts into 8 ohms. After it had been running for a couple of hours it sounded crazy good...but prior to that it was merely competent. Sold it due to heat and waiting 2 hours was simply too long for it to come on song.
The second best was a Sphinx Project 14 mkIII, which was about 24 watts class A with the rest AB. Also a hybrid but a more conventional PP amp. The Sphinx Project 16 was an amazing true Class A hybrid but very rare.
1. pure class A sounds best.
2. high bias class AB sounds second best.
3. sliding bias "class A" sounds worst. Nonlinear modulation distortion which can't be recovered by human brain.
Edits: 11/21/24
"Sliding" Class A is not the same as the step function Class A used by some Krell amps. When they're running Class A as the music is playing it is truly Class A biased.
Unless you can predict music, otherwise you always fall behind.
Unless you have a 20 second or longer gap in the music or between tracks it doesn't 'fall behind'. I never experienced it. I believe Krell had a patent on that clever design. But all of that aside, the KSA-50S was a very robust and sweet sounding amp that like many Krell (and BMW's) output significantly more power than shown on the manufacturer's spec sheet.But there are different ranges of Krell products. I also had the KAV-2250 for a short while. That was a powerful but awful sounding Krell as was the case with many of their "KAV" products including one of the preamps I had.
The 'baby Krell' KSA-50S which was their smallest "Sustained Plateau Bias" amp of that era was released in the early 1990's but I wouldn't consider buying any 30 year old amp today.
I personally wouldn't consider a true Class A amp for a few reasons including my listening habits. I want to power up the equipment and start listening immediately. Class A amps can take a good hour to "warm up" all that thermal mass to sound their best. The other option would be to leave the Class A amp ON 24/7. Not advisable with that constant huge AC power consumption and space heater heat.
Edits: 11/22/24 11/22/24 11/22/24 11/22/24
1. KSA200. heatsink too small, had field issue.
2. KSA250. greatly reduced bias. about 30W in class A.
3. KSA200S. variable bias.
Edits: 11/22/24
Krell KSA-200S Class A bias resides at 5 discrete steps, not continuously variable. Regardless, I'm pretty much done with huge power amps while I enjoy the efficiency and excellent sonics from modern Class D.Sustained Plateau Biasing
How is a modern, high-performance, "class-A" amplifier designed to have a low, "green," standby power consumption?Obviously, the class-A designation requires that the dynamic music envelope fits within a static, class-A current and voltage combination for a rated load impedance. Many "dynamic" or pseudo-class-A designs do not feature true class-A operation for their output stages. Generally, the "dynamic," "sliding-bias," and "Stasis" amplifier designs feature signal-controlled biasing of the output stages. The bias level is wound up according to the signal's current demand, with its minimum value carefully controlled to avoid classic class-B crossover distortion. Complex circuitry is common, with unwanted, signal-related modulation effects sometimes apparent in the output waveform.
In the case of the current Krells, several factors working in combination appear to redefine the topic of dynamic biasing. The key to the design was the use of an ultra-fast bias-control circuit. The technology was borrowed from the high-speed, current-feedback amplifiers used for I/V conversion in digital systems.
Using current-feedback technology, this bias circuit looks ahead at the music envelope, and predicts and then sets the output stage's equivalent class-A bias levels before that same music's leading edge has actually passed through the amplifier's circuit. When it finally arrives at the end of the relatively slower main amplifier chain, the required bias level has been anticipated; the output stage is therefore in a relatively stable, static condition of class-A bias current.
Krell has avoided the worst music-related modulation effects by learning from the psychoacoustic aspects of the design of compressor/limiters. Such limiters have a fast attack and a slow decay. Similarly, the slow decay of the Krell's bias level after a music transient has passed allows the whole decay envelope of the music to reach completion long before any bias shifts occur. A very generous delay of 20 to 30 seconds is provided before any downshifting of bias occurs.
Another factor reducing the potential audibility of such program-related "gear changing" is the concept of "plateau biasing" at one of five appropriate levels. This means that the bias level is not constantly dynamic, but varies with the program power envelope only over a few preset levels.
The bias in this Krell series of designs settles at one of the five levels for an extended period, and is not switched up or down unless the longer-term power demand needs it. This means that the bias level is not being switched very often, and then only for an instant of transition. Thus, signal-induced distortions, if present, can only occur for a tiny fraction of the time. The prolonged plateau bias levels do, in fact, imply a very high proportion of true, non-varying class-A operation.
Concerning the relative "speeds" of the power amplifier and the bias anticipator, Krell correctly reminds us that the maximum slew rate found in high-level recorded music is a modest 10V/µs. The "S"-amplifiers have an intrinsic slew rate well above that at 100V/µs, ensuring a generous safety margin. On the other hand, the anticipator circuit operates at a "speed" in excess of 1000V/µs, well in advance of the main amplifier.
Edits: 11/22/24
.
While Krell KSA250 sounds very very nice, it is not a pure class A amp.
Looking inside the KSA-250, the emitters of the 12 pairs per channel of output-stage transistors appear to standing on series resistors of nominal 1 ohm value. The average voltage drop across these resistors was 110.5mV, implying a standing bias for each of 110.5mA; ie, a total of 1.33A. This will give a maximum power for true class-A operation into 8 ohms of 28.5W (14.5dBW) rather than 250W.
Krell's true class A amp is the 200W class A KSA200. But they had some field issues (amps burnt out). Therefore KSA250.
I had been recommended the old Classe DR-9 from Oakroot some time ago and I found one and it is a gem. Oakroot was using his in the bridged mono mode for the big Sound Labs. I've been using mine for Vandersteens, EdgarHorns, Altec Model 14s and many others. It just makes music and will drive anything. It's a Class A/B with a high bias on Class A and will warm your room in winter.
Surprisingly, there is one on canuckaudiomart.com. If you didn't like it, you could easily sell it, possibly for even more.
-Rod
Back in the 90's I was at a local stereo store and I wanted to hear the SUMO Andromeda III with some B&W 801 Matrix. They used the Kimber 8TC speaker cable which are higher capacitance wire. I don't remember the front end CD player but it was paired with the SUNO Athena II preamp.
The sound was really nice but when I asked him to turn it up to a good level like how I would listen to at home, it went a few seconds sounding really nice then nothing. Turned out to be that the amp popped its fuses. He replaced the fuse and lowered the volume and all was ok again.
Fast forward to the mid 2000's, I had a chance to hear those B&W 801's again but this time with a McCormack 3.0 power amp and the result was simply stunning. That combo was very nice and drove those 801's to really nice levels without any hint of strain.
So the 801's need good power and a good amp that can drive difficult loads. Which amp you choose is up to what you can afford and like. I think the newer Class D amp like the Nilai 500 DIY Mono blocks would do good since they were design to handle any load from what I have read from other with those amps and speakers that are difficult to drive without any issues. I have this Nilai amp and it never strains with my power hungry Clearfield Continentals which are 87db 4 ohm speakers. They sound good at low & high levels and drives them up to good sound levels. It's a good price and good power to drive most speakers if you are into Class D. It one of the best sounding class D amps I have heard. They don't flinch even down to 2 ohms loads.
Now if you want a traditional AB amp, there are many to choose but again just make sure it has good drive capability.
As for the 801's, these are very fine sounding speaker and look really nice. I have always wanted a pair but now I don't have the room for them. These were used alot in the Studios as well.
> I think the newer Class D amp like the Nilai 500 DIY Mono blocks would do good since they were design to handle any load from what I have read...I recently switched from class-A/B to class-D power amplifiers and I couldn't be happier. I'm nearly 77-years old now and I just can't lift the heavy class-A/B power amplifiers anymore. Furthermore, the price of high-power class-A/B amplifiers is way more than I can afford. Consequently, when I saw Stereophile give an "A" rating to PS Audio class-D amplifiers in their Recommended Components , I decided to take a chance and give them a try.
My first class-D amplifiers were the PS Audio Stellar M1200 monoblocks because I needed high-power to drive my Thiel CS3.7 speakers. Currently, I'm listening to Mini Maggie speakers powered by the Nilai 500 Mono Block Amplifiers. These little 500-watt monoblocks sound as good if not better than my PS Audio Stellar M1200 monoblocks.
As far as I'm concerned, class-D is the way to go nowadays if you want the best bang-for-the-buck in a relatively lightweight package. I just can't get over how nice these Hypex Nilai 500 Mono Block Amplifiers sound.
Happy listening!
Edits: 11/21/24
power cords, input connectors along with the input cables to better Rhodium plated. Totally changed the sound for the better. I was so so on the amps at first and for weeks, then after the change they went up to another level in sound and have been a happy camper ever since.
Like you I have a hard time moving these big amps even when using a Dolly. I had a back injury back in 2011 and that change everything. I'm now way better off and can do alot of things but have to be careful when I move heavy amps now, the Nilai amps are so lite, my back love them plus they sound really nice now. My EDGE amp still is the king but not by much. :)
Human will get used to their environment. When you listen to class D for a while you forget the sound of class A. You will be happy with the class D sound.
OK, I bought another Crown XLS 2502. I am going to bridge them. 1550W each channel. That is enough wattage.I do not object class D. But I also do not pretend that class D is as good as any class A. I know its limitation. I bought them because them are good value and strong driving capability.
They have open box for cheap. When I got mine last time, the box was sealed and can't tell any difference from new.
Edits: 11/21/24 11/21/24
I just got another Crown XLS 2502 from FedEx. I ordered an open box. But the one I got I can't tell it is used or not. Looks like new. I will bridge these two 2502s. They will output 1550W at 8 ohms per side. This is crazy. Lets see.
For new Crown XLS 2502 amp, you need to use a screw to remove the plastic protection plugs from the banana binding posts.
Edits: 11/24/24
I am quite surprised:
1. Nobody mentioned bi-amp.
2. If more power is better, isn't a class D amp a better choice?
When I had my Matrix 801s I started out with a 200 W Rotel power amp. The sound was good with the Rotel, and immediately went to great when I shifted to a pair of 500 W Bryston 7BST mono blocks. The added power really woke the 801s up.
Edits: 11/14/24
Doesn't a 400W amp sound coarse?
It did not sound coarse to my ears. Currently running 650 W Brystons that are very smooth.
These speakers need a high power high current solid state amp. I used a Pass Labs X250.5 with mine and found them to be excellent.
In my B&W Matrix S3, I used a high-powered Krell EVO 402 and the Krell EVO 202 preamp with great results. Before these, I was using the high-powered ARC D-250 tube amp (250 w/c) and ARC Ref1 preamp also with great results although the bass was a little bit wolly.
Get a 200 watt per side early 90s Levinson and be done with it.
Which models? ML332, ML333?
23.5, if you can find one. As there is a house sound others would likely sound bueno.
B&W speakers tend to like power, especially the big ones. They need the control. You can use either tubes or SS, but tubes with the power you need will cost you. You don't give your budget. You may want to look into class D amps too.
Good luck,
Jack
Sorry, but there is no "best" amplifier, unless you state your budget. Even then, your music tastes and room acoustics will be very important, so your best bet is to try a few contenders at home first.Make a shortlist based on recommendations from reputable reviewers, other B&W 801 users and other research. If your budget is substantial, you should find dealers to loan you one from your list.
If your budget is tiny, best to buy used examples from your list and re-sell ones that don't meet your taste.
I bought or borrowed 10 amps 3 years ago in the GBP 3-8K range when I decided to switch from tube to ss amplification. These were Class A, AB and D, but it was surprising how much they varied and my chosen one was not what I was expecting by any means. I returned or re-sold the others at virtually no loss. I can't recommend an amp as your speakers (and room and probably music taste) are very different from mine. Good luck
Edits: 11/17/24
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