Re-imagining "Class A" Amplification

Steve Williams

Site Founder, Site Owner, Administrator
Well it's finally today and after a week of waiting I can honestly say that today was a revelation as I heard a giant slayer. Thanks once again to Gary for shlepping this gear from Newport Beach to my house. The reality is that this is far from a schlep as I could carry both these amps up my stairs, oner under each arm. Today I heard the "full Monty" as Gary obliged me when I asked if he would bring the matching Westminster preamp. Not only that Gary also brought with Angus, PC's as well as his speaker cables. We carried everything from curb to my sound room in under 5 minutes.


IMG_2021.jpeg

As to the preamp , what an absolute beauty in the simplicity of design. It was bigger and heavier than the amp and I was told the preamp contained 8 separate power supplies. This visit we had adequate length and type of interconnects and Gary also brought a Star Grounding device which we used

Gary and I listened for 3 hours and this system amp, and preamp is for my ears an absolute game changer. The heat sinks after about 30 minutes were warm at most to the touch. They got slightly warmer but never hot to the touch. What has fascinated me all along reading about this amps how is it possible to be class A yet weigh all of 30 pounds, putting out 100 watts into 8 ohms and 200 watts into 4 ohms (please correct me if this is inaccurate). Gary also talked about strapping a pair of these per channel to increase the output. In my room this is the first time I have had solid state state amplifiers and the last time I owned SS amps was my Krelll 750 mcx, so many years ago. Since that time my system has been 100% tubes. (SET system). I can say that I never once felt lacking for power today with just 100 wpc. I can only imagine how a pair of these per channel would sound

After we placed everything and hooked it all up I was listening to an entire Westminster system. This was one of the best listening sessions I can recall in years. When this happens, I always ask myself, "is it something better or just something different?" Well a whole lot of both actually. These little amps threw such a believable sound stage that I was transfixed. I was looking to find fault with something but I gave up as everything was perfect. Timbre, tone, dynamics were so good and so realistic and the bottom end had such grip that I skipped through we'll over 50 of my demo tracks looking for fault. The more I listened the more I was convinced that whatever new technology Angus has used in the development of this amp and preamp he has hit a "walk off home run " at his first at bat. Certainly I love the sound of my SET and have no intention of switching paths at this time in my life, I told Gary that people who are assembling a system n ow or looking just for an amp or preamp, they must audition these little amps. They will blow yourmind. I sensed no coloration and there was certainly no distortion regardless of the volume and we cranked the amps and our ears were bleeding when the gain level on the preamp was up only 1/3 of the way on the control. BTW, the preamp is operated by a small thin remote that looks identical to the remote for my Lampi Horizon which was the only source we used today.

I streamed through my Extreme for half the session and then listened to internal files on the Extreme for the balance. of the session.

Gary and I listened to a lot of music today and there were things that I have never heard on songs that I have played 100's of times. The micro and macro dynamics produced a true suspension of disbelief for me today. There was such a sense of grip to the sound, yet the decay was equally impressive as sound trailed off. There was a sense of presence (which I cherish in my system) that was every bit there today.

We initially played the system using my MasterBuilt Ultra speaker cables (which are keepers in my system) and I was getting goose bumps with many of the songs. Switching to Angus SC's produced beautiful sound. I asked Gary if the cables had been burned in and there were about 100 hours on them. I felt the sound continue to improve the more we listened , as these cables settled

In short ....

Class A dual mono amps weighing 30 pounds.........Price &28,900

Preamp that is simply beautiful, sleek yet elegant in design staring at $22,000 and add another $2200 (IIRC) for a phono stage card

Cables were solidly built yet also simplistic in design

Personally, I thought this system to be so good that if I were to buy the amps, I would also buy the matching preamp. These prices are shockingly low for sound that was so wonderful in every way.

Kudos to Gary for developing this relationship with Angus and what I heard today is proof that manufacturers aren't churning out mere variations of the same thing but are developing new technology in keeping with progress and evolution in high end audio. Don't be swayed in a negative way by the price. I have no doubt that these little amps will compete quite favorably with amps priced 5-6 times higher and when strapped, all bets are off
 

gleeds

Industry Expert
May 29, 2018
342
456
150
Appreciate the time and effort, Steve. It was a blast rifling through your reference recordings with you yesterday. Will follow up with some additional system details a bit later.

For now...........a little-known fact about the Doc is now known to the members of WBF - Steve Williams is a legit POWER LIFTER:)
 

gleeds

Industry Expert
May 29, 2018
342
456
150
Steve, thanks again for a terrific day and your positive comments on your experience with Westminster Lab.

All, a few clarifications and additional information:

There are 10, not 8 power supply rails in the Quest pre-amplifier (my misquote Steve) Here is a brief description of how that works.

2-stage linear regulation is adapted to exert more control on the regulation
2-stage linear regulation is adapted to exert more control on the regulation
The power supply design of the Quest provides a foundation for the pre-amplifiers extraordinary musical performance. With (10) separate power rails, they provide the highest possible separation between different channels and for different parts and modules within the unit. Different rails are designed specifically to the needs of different sections of the particular part due to the varied needs and conditions, ensuring ultra low noise performance to deliver maximum micro-dynamics and details. A separate transformer and power supply are dedicated for the non-audio section. For certain ultra-sensitive components, 2-stage power regulation is added.

Pricing: Quest Preamplifier: $21,000 - Options/features include:
1. Extended carbon pack for even lower noise - $2200
2. Remote trigger pack (one for each Rei amplifier) $800
3. optional RCA input card - $1600
4. Upcoming moving coil phono card - Price TBA
5. Quest is also available in a dual-mono configuration (price and details TBA)
6. Include a switchable "on the fly" grounding scene for various system configurations and the lowest possible noise

Weight: 30 pounds

Pricing for Rei amplifiers:
Single pair: $28,900.
Dual bridged pairs: $57, 800 (per side - 400 watts @ 8ohms and 800 watts @ 4ohms)
Remote turn-on and additional mains grounding pack - $1490

Weight of each amplifier: 35 pounds
(Steve, you are even stronger than you thought!)
 
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lscangus

Industry Expert
Oct 24, 2018
124
104
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35
Well it's finally today and after a week of waiting I can honestly say that today was a revelation as I heard a giant slayer. Thanks once again to Gary for shlepping this gear from Newport Beach to my house. The reality is that this is far from a schlep as I could carry both these amps up my stairs, oner under each arm. Today I heard the "full Monty" as Gary obliged me when I asked if he would bring the matching Westminster preamp. Not only that Gary also brought with Angus, PC's as well as his speaker cables. We carried everything from curb to my sound room in under 5 minutes.


View attachment 92466

As to the preamp , what an absolute beauty in the simplicity of design. It was bigger and heavier than the amp and I was told the preamp contained 8 separate power supplies. This visit we had adequate length and type of interconnects and Gary also brought a Star Grounding device which we used

Gary and I listened for 3 hours and this system amp, and preamp is for my ears an absolute game changer. The heat sinks after about 30 minutes were warm at most to the touch. They got slightly warmer but never hot to the touch. What has fascinated me all along reading about this amps how is it possible to be class A yet weigh all of 30 pounds, putting out 100 watts into 8 ohms and 200 watts into 4 ohms (please correct me if this is inaccurate). Gary also talked about strapping a pair of these per channel to increase the output. In my room this is the first time I have had solid state state amplifiers and the last time I owned SS amps was my Krelll 750 mcx, so many years ago. Since that time my system has been 100% tubes. (SET system). I can say that I never once felt lacking for power today with just 100 wpc. I can only imagine how a pair of these per channel would sound

After we placed everything and hooked it all up I was listening to an entire Westminster system. This was one of the best listening sessions I can recall in years. When this happens, I always ask myself, "is it something better or just something different?" Well a whole lot of both actually. These little amps threw such a believable sound stage that I was transfixed. I was looking to find fault with something but I gave up as everything was perfect. Timbre, tone, dynamics were so good and so realistic and the bottom end had such grip that I skipped through we'll over 50 of my demo tracks looking for fault. The more I listened the more I was convinced that whatever new technology Angus has used in the development of this amp and preamp he has hit a "walk off home run " at his first at bat. Certainly I love the sound of my SET and have no intention of switching paths at this time in my life, I told Gary that people who are assembling a system n ow or looking just for an amp or preamp, they must audition these little amps. They will blow yourmind. I sensed no coloration and there was certainly no distortion regardless of the volume and we cranked the amps and our ears were bleeding when the gain level on the preamp was up only 1/3 of the way on the control. BTW, the preamp is operated by a small thin remote that looks identical to the remote for my Lampi Horizon which was the only source we used today.

I streamed through my Extreme for half the session and then listened to internal files on the Extreme for the balance. of the session.

Gary and I listened to a lot of music today and there were things that I have never heard on songs that I have played 100's of times. The micro and macro dynamics produced a true suspension of disbelief for me today. There was such a sense of grip to the sound, yet the decay was equally impressive as sound trailed off. There was a sense of presence (which I cherish in my system) that was every bit there today.

We initially played the system using my MasterBuilt Ultra speaker cables (which are keepers in my system) and I was getting goose bumps with many of the songs. Switching to Angus SC's produced beautiful sound. I asked Gary if the cables had been burned in and there were about 100 hours on them. I felt the sound continue to improve the more we listened , as these cables settled

In short ....

Class A dual mono amps weighing 30 pounds.........Price &28,900

Preamp that is simply beautiful, sleek yet elegant in design staring at $22,000 and add another $2200 (IIRC) for a phono stage card

Cables were solidly built yet also simplistic in design

Personally, I thought this system to be so good that if I were to buy the amps, I would also buy the matching preamp. These prices are shockingly low for sound that was so wonderful in every way.

Kudos to Gary for developing this relationship with Angus and what I heard today is proof that manufacturers aren't churning out mere variations of the same thing but are developing new technology in keeping with progress and evolution in high end audio. Don't be swayed in a negative way by the price. I have no doubt that these little amps will compete quite favorably with amps priced 5-6 times higher and when strapped, all bets are off
Hi Steve, great to know that you like what we are doing!

What I personally loves about your hearing notes is the bit which mentions how sound trailed off. We really did put a lot of effort in keeping those micro details and dynamics. We listen to all sorts of music, so it is important to make all of them sound right.
 
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skids929

Active Member
Dec 31, 2020
167
78
33
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Thanks Steve, great review and thank you (and Gary) for taking the time to pull it all together for us lay folks to enjoy. Would love to hear these.

Question, what is the volume control in the pre? Looks like a Khozmo, but I could be wrong.
 

gleeds

Industry Expert
May 29, 2018
342
456
150
Great eye Jeff!

Indeed the Quest pre-amplifier uses the excellent Kozmo VC controllable in 1-decibel increments.
 
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Steve Williams

Site Founder, Site Owner, Administrator
Great eye Jeff!

Indeed the Quest pre-amplifier uses the excellent Kozmo VC controllable in 1-decibel increments.
I loved the volume control display on the preamp. Nothing fancy about the remote which is very sleek and easy to use. I bet that the same company that makes the remotes for Lampizator also makes the remote for the Westminster preamp.

Gary, I am still hearing in my head some of the music we played on Wednesday. For the price this system IMHO is truly a giant slayer
 
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bonzo75

Member Sponsor
Feb 26, 2014
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For now...........a little-known fact about the Doc is now known to the members of WBF - Steve Williams is a legit POWER LIFTER:)
? Are you saying that because of how he lifted the amps or is he actually training weights?
 

Steve Williams

Site Founder, Site Owner, Administrator
? Are you saying that because of how he lifted the amps or is he actually training weights?
I lift stacks of Westminster Lab amps. It's a walk in the park:p
 
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bonzo75

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Feb 26, 2014
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gleeds

Industry Expert
May 29, 2018
342
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Several have inquired via DM, so please allow me to post for others who may be curious about Westminster Rei and Quest functionality.

The Rei amplifiers have an on/off toggle switch located in the lower right below the illuminated logo.
The amplifiers are available with a 12v trigger for remote on/off turn on from your pre-amplifier.

The Quest pre-amplifier uses a handheld remote to activate all primary control functions. On the bottom right of the chassis is a master on/off rocker switch.
Features accessed from the remote include:
- on/off
- volume up down in one dB increments
- mute
- source selection


Additional pre-amplifier features:
- large LED display
- power phase switch for lowest noise via a toggle located on the bottom center-front
- two expansion bays, e.g. upcoming MC phono card
- dual balanced output for use with multiple amplifiers
- three fully balanced inputs
- 1 single-ended input option
- full carbon shielding package upgrade
_ANG2894-HDR-Remote.jpg Quest backplate_ANG1788.jpg _ANG2894-HDR-Remote.jpg
 
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CDC77

Active Member
May 27, 2021
55
105
40
Chicago
www.cdcaruso.com
Questions posed by the Members above are commonly raised questions from our customers and distributors.

We really wish we are the first ones to have cracked it! But we are not the first one using the idea of dynamic bias on the market, i.e. in the past, Krell was using a similar kind of technology for some of their products.

The heat dissipation of an amplifier depends on a lot of factors while many people usually consider only the BIAS ( class A, AB ). Some manufacturers decided to tune the bias much higher than required to classify an amplifier as Class A ( I guess mostly for sound tuning purposes ). Surely higher bias results in more drained current, energy losses, and heat.

But one important factor always being missed is the rail voltage. The higher the voltage the more heat is dissipated as the bias is draining. Because of the higher efficiency (impedance ) of modern speakers, we have designed the Rei to have a lower rail voltage compared to many amps on the market. A lower rail voltage will result in much less heat when the bias current continuously drains. For users who need more voltage ( bigger room or listening at very high volume ), we designed the Rei to be able to run in bridge mode to address those demands. Of course, a single pair of Rei will power a majority of today's top-class loudspeakers under normal operating conditions. That said, I enjoy the extra power of the Rei's in bridged mode when powering my Giya G1.

Then we may also think about the number of output transistors. Let’s say if two amps tuning both bias as 1A, holding all other factors constant. 10 transistors in total will be hotter than 5 transistors ( more or less twice at hot ). You may think the output power delivery of the 10 transistors amp will be higher, this is not necessarily true as different transistors have different current delivery patterns. We have chosen a transistor with a higher (compared to more typical ones) current delivery. By limiting the number of output transistors, and combining with the advantages we have with lower rail voltage as stated, together with the utilization of dynamic bias, the final result is much less heat dissipation than usual for Class A amplifiers.

The rated output is also one of the key points too. Using your example, Accupahse A75 designed the output at 60watt so as to double down to 1 ohm at 480 Watt. A choice we made very early in the design stage was to consider the majority of modern loudspeakers rarely dip down to 1ohm, and for the ones who do ( i.e. ribbon ), the impedance does not fluctuate that much. We do not need the Rei to double down to 1ohm, which allows us considerably more room to tune for higher power at 8,4,2 ohms.

The power supply is actually quite big in the Rei, as it only supplies to one channel of the Amp. Also for the performance of a heatsink, it depends on a lot of things. i.e. the airflow dynamic, material, material density, profile design, surface finishing, etc. It is not that a bigger and heavier heatsink must do better than a smaller lighter heatsink. For us, it's all about optimisation and choosing the right approach to all aspects of the design in concert with our design priorities.

Addressing the question concerning weight, if you want, there are lots of ways to increase the weight of an amplifier such as encasing the transformer, using steel rather than aluminum alloy, etc. Let’s say just by swapping out the top and the bottom cover of the Rei from Carbon to Aluminum and changing the main chassis to steel, the unit will be 5kgs heavier. But we have to do it this way for good reason.

We don’t know if the Rei will overturn some common concepts and ideas about Class A amplifiers, and, of course, we cannot make it overcome the laws of physics. That said, we just don’t want to make a usual or expected product - we want to advance the state of the art and at the same time produce, beautiful, simple products that will stand the test of time.

Rei is a real Class A amplifier

Sincerely, Angus
May I ask this question: How do you respond when a “traditional” Class A manufacturer argues that “bias” is never a perfect substitute for power because it is impossible to anticipate in advance when the next surge will be required in any given song, unless of course the song is memorized before it is played? I apologize in advance if my question reveals a lack of understanding of your technology. Thank you.
 
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lscangus

Industry Expert
Oct 24, 2018
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May I ask this question: How do you respond when a “traditional” Class A manufacturer argues that “bias” is never a perfect substitute for power because it is impossible to anticipate in advance when the next surge will be required in any given song, unless of course the song is memorized before it is played? I apologize in advance if my question reveals a lack of understanding of your technology. Thank you.
Yes, the system can never predict the next surge as it does not read ahead. The dynamic biasing lowers its bias slightly when the loading is not that big. We still leave a huge headroom above the music level just in case the music is going to get loud later on, and when the music is louder by then, it will adjust the bias to be higher just to get enough headroom. So if your music is very quiet and suddenly super loud, then there may be slight second it will be out of the "Class A" and into the "Class AB" territory. But is a very very rare occasion after warming up.
 

marty

Well-Known Member
Apr 20, 2010
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May I ask this question: How do you respond when a “traditional” Class A manufacturer argues that “bias” is never a perfect substitute for power because it is impossible to anticipate in advance when the next surge will be required in any given song, unless of course the song is memorized before it is played? I apologize in advance if my question reveals a lack of understanding of your technology. Thank you.
Excellent question and one that every Class A amplifier designer has to consider. When Flemming Rasmussen designed the Gryphon class A amps, he felt there was no short cut as anything less than full bias meant the amplifier devices were not operating in their ideal linear range. The trade off is of course, heat. He therefore eschewed floating bias. although he does offer reduced fixed bias options with the push of a button on the front panel. But it is magic you want, there's a price to be paid. Full class A bias may not be much of a heat issue for a 30W amp, but for a kilowatt amp, it's another story completely.
 
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CDC77

Active Member
May 27, 2021
55
105
40
Chicago
www.cdcaruso.com
Yes, the system can never predict the next surge as it does not read ahead. The dynamic biasing lowers its bias slightly when the loading is not that big. We still leave a huge headroom above the music level just in case the music is going to get loud later on, and when the music is louder by then, it will adjust the bias to be higher just to get enough headroom. So if your music is very quiet and suddenly super loud, then there may be slight second it will be out of the "Class A" and into the "Class AB" territory. But is a very very rare occasion after warming up.
Thanks for a great answer, I was a little worried I was asking a dumb question. And now I am trying to think of music that might put it to the test. some songs from my misspent youth come to mind, like Over the Hills and Far Away by Led Zeppelin, when Jimmy Page’s electric guitar comes crashing into what started out as an acoustic number. assume you have the headroom for those types of moments, which were not infrequent when bands like Zeppelin and The Who roamed the earth?
 

Steve Williams

Site Founder, Site Owner, Administrator
Excellent question and one that every Class A amplifier designer has to consider. When Flemming Rasmussen designed the Gryphon class A amps, he felt there was no short cut as anything less than full bias meant the amplifier devices were not operating in their ideal linear range. The trade off is of course, heat. He therefore eschewed floating bias. although he does offer reduced fixed bias options with the push of a button on the front panel. But it is magic you want, there's a price to be paid. Full class A bias may not be much of a heat issue for a 30W amp, but for a kilowatt amp, it's another story completely.
The Westminster Lab is not a 30 watt amp. Quite the opposite. Stats on the amp are stated here in this thread many times. Perhaps you were thinking of the weight of the amp which is 33 pounds. My amps are 32 wpc Pure Class A and weigh 5 times what the Westminster Lab amp weighs. My amps IMHO are magical but I can honestly say the WL amp is beyond anything I have ever heard in such a small package. I was simply blown away by how good they sound

IMO anyone who hears these Westminster Lab amps (especially strapped per channel) they are going to be gobsmacked and when you look at the price per pair after you hear them you have to rethink everything you have considered previously as sacrosanct. Gary and I played every genre of music we could throw at it and it never once clipped or gave up the ghost. There was a ton of headroom. I would submit to anyone who hears these and are looking for something superb and not $175K these amps are the real deal. If they quickly go in and out of Class AB for a microsecond with a delay, we never heard that when we played everything through them.. The magic is indeed there and IMO Angus has brought something to the market that is so unique it will cause everyone to rethink what they have etched in their minds.
 

gleeds

Industry Expert
May 29, 2018
342
456
150
Thanks for the feedback, ALL! Steve, we certainly appreciate your reinforcing Westminster gear is something worth a serious listen.

Class A amplifiers are highly regarded, so we welcome comparisons and questions relating to other Class A designs. Please keep them coming, and we will do our best to continue answering your questions.

The bias topology is not the only element that makes the Rei monos remarkable amplifiers. The proof is, of course, in the listening. We have US demo units beginning to circulate, so if anyone is seriously looking for something special in a SS amplifier, do let me know.

On a related note, Angus is proud to announce the presentation of the prestigious Fidelity Magazine of Germany 2022 Innovation Award.

westminsterlab-rei-lizenz-en.jpg
 

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