Re-imagining "Class A" Amplification

gleeds

Industry Expert
May 29, 2018
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Westminster Labs: An Introduction
Since 2007 Westminster Labs has been crafting high-performance cables and electronics primarily for the Asian and European markets where they have received critical acclaim. With the introduction of their Rei monoblock amplifier and Quest pre-amplifier, we have something entirely new for the US market to take note of. Angus Leung, Westminsters' visionary Founder has achieved (at a relatively young age) what usually takes a lifetime to accomplish. Angus will be joining us on WBF to answer questions about his journey creating these remarkable instruments and to dive into the technical details so often of interest to WBF readers.

Rei Monoblock Amplifiers: Pure Analog "Class A" power in a Compact Package
Fully balanced from input to output, the REi monoblock amplifier remarkably produces 100 watts per channel of power from an understated and compact chassis. A pair of Rei's are not only easy to handle but also fit perfectly on any standard equipment rack, dedicated amplifier stands, or discretely hidden behind your speakers.

Power to Spare
Each Rei doubles its power with declining impedance, producing 200 watts/channel into 4 ohms and 400 watts/channel into 2 ohms. For those wanting even more power and control, two Rei's (for a total of four mono amplifiers) can be daisy-chained doubling the total available power with zero reduction in sound quality. Vertical bi-application and other combinations are a welcome option.
REI-closeup-front.jpg


Rei3-4.jpg


Rei (continued)
Performance and Quality in the Details

The amplifiers use no global feedback and are DC coupled. Westminster Labs' proprietary VARI-BIAS circuit brings the amplifier to optimal operating temperature in minutes and maintains it regardless of load or operating conditions. The amplifiers throw off surprisingly little heat remaining warm to the touch.

Key elements of the amplifier's design include precisely matched output transistors, a muscular, lightning-fast power supply, perpendicular wiring paths, use of specially developed ultra-thick PCB boards, stainless steel fasteners, and a single asymmetrical heatsink. These and other elements of Rei's design are focused on reducing micro-vibrations and minimizing electrical, mechanical, magnetic, and airborne induced distortions.

REi transistor-bank.png


The Quest Pre-amplifier: A Worthy Companion
The Quest pre-amplifier is a study of what a modern pre-amplifier should be. Full carbon shielding, separate power supplies for the audio signal, switching, and control systems. Utilizing the same obsessive attention toward reducing micro-vibrations as the Rei contributes to a control center worthy of forming the foundation of a modern, ultra hi-end analog and digital system. Fully balanced from input to output, Quest offers 3 balanced and a single (optional) single-ended input, as well as two analog outputs for use with multiple power amplifiers. All functions from volume control to source switching are conveniently managed by the supplied handheld remote control.
Quest-herosot-best.jpg Quest-rearpanel-2.jpg Questwit-powersupply_ANG1743.jpg



The Finishing Touch: Westminster Labs Cables
Rounding out Westminsters' approach to the analog signal chain is their comprehensive line of cables available in both Standard and Ultra level trim. Optional carbon fiber sleeving is available for both as an option to bring these exceptionally quiet, dynamic, and detailed cables to the next level of performance especially, in ultra-high-resolution systems. A white paper describing Westminster cable technology is available upon request by contacting gary@hearthis.us

FEATURE HIGHLIGHTS
• custom formulated alloy with unique temperature treatment
• polished, coated, weaved, soldered, and finished 100% in house by hand
• proprietary soldering technique for the perfect joint
• "Vari-twist" technology for balanced performance across the audio spectrum
• optional real Carbon Fibre external shielding for unprecedented background darkness




_ANG1847-Power_Ultra.jpg
_ANG2918-HDR-XLR_Ultra.jpg
_ANG1195-Speaker_Standard.jpg

hear-this-logo.gif

www.hearthis.us
Gary Leeds
Tel: (949) 467-9808
Email: gary@hearthis.us
 
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Fred Crane

Industry Expert
Apr 23, 2020
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I've spent the last week getting to know this equipment. I've had the amps and preamp on every different types of speakers we have to see how it handles Scintilla like loads on the one hand, and 107 db sensitive horns on the other. Still haven't put in their cables. I hope to do that this evening.

The real take away for me is that this is a different kind of amplification...I know it's class A, but it has its own gestalt which required a re-wiring of the way I hear and audition. Often times my favorite gear asks this of me. You have to go into this realm understanding that this is a new ballgame. The images are dense...players pop out of thin air. Granted, I've only been playing around with these pieces for about a week, but they're something special. The fact that you can very simply daisy chain the amps to go to 200@8, 400@4 and 800@2 (and I think even beyond that if one wanted to daisy chain 3 amps per side) makes them even more compelling for all kinds of applications. For instance, one system I favor is comprised of large OB's in a large room. 3 amps per side would be the ticket. They were designed for this expansion without any deterioration to the signal.

There's also an industrial art to these pieces. Carbon Fiber used to isolate within the amps and preamp...every trick known and a few unknown to limit vibration and shorten signal paths. There was something about custom extra thick PCBs as well. All to say, very thoughtful engineering and construction. My Better Half thought they looked great compared to some of the massive amps I've had in house. These guys are small but without compromise so far as I can hear. A must audition...even if they're not to your liking, you want this sound in the aural rolodex of your brain...I have a feeling this tech is going to be around for a good long while. I'd be shocked if other companies didn't borrow from them.
 
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lscangus

Industry Expert
Oct 24, 2018
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Hello All. Let me introduce myself to this forum and thread. I am Angus and I am one of the founder of WestminsterLab. Feel free to hit me any questions about anything and I will try my best to answer here.
 

lscangus

Industry Expert
Oct 24, 2018
121
96
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I've spent the last week getting to know this equipment. I've had the amps and preamp on every different type of speaker we have to see how it handles Scintilla like loads on the one hand, and 107 db sensitive horns on the other. Still haven't put in their cables. I hope to do that this evening.

The real take away for me is that this is a different kind of amplification...I know it's class A, but it has its own gestalt which required a re-wiring of the way I hear and audition. Often times my favorite gear asks this of me. You have to go into this realm understanding that this is a new ballgame. The images are dense...players pop out of thin air. Granted, I've only been playing around with these pieces for about a week, but they're something special. The fact that you can very simply daisy chain the amps to go to 200@8, 400@4 and 800@2 (and I think even beyond that if one wanted to daisy chain 3 amps per side) makes them even more compelling for all kinds of applications. For instance, one system I favor is comprised of large OB's in a large room. 3 amps per side would be the ticket. They were designed for this expansion without any deterioration to the signal.

There's also an industrial art to these pieces. Carbon Fiber used to isolate within the amps and preamp...every trick known and a few unknown to limit vibration and longer signal paths. There was something about custom extra thick PCBs as well. All to say, very thoughtful engineering and construction. My Better Half thought they looked great compared to some of the massive amps I've had in house. These guys are small but without compromise so far as I can hear. A must audition...even if they're not to your liking, you want this sound in the aural rolodex of your brain...I have a feeling this tech is going to be around for a good long while. I'd be shocked if other companies didn't borrow from them.
Hello Fred, the Rei can be scaled up in two ways. One is the traditional bi-amping, so you will run two sets of speaker cables individually to the binding post of the speakers. The other way is by bridging two units together into one unit. By bridging 2 units, you will get effectively get 400@8 and 800@4 output. We are currently using this configure with 2 Quest preamplifier ( in mono mode ) in our own testing facility, we did try out a Bi-Bridge configuration with a total of 8 unit of Rei too.
 

audio.bill

Well-Known Member
May 27, 2013
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275
Chicago suburbs
Hello All. Let me introduce myself to this forum and thread. I am Angus and I am one of the founder of WestminsterLab. Feel free to hit me any questions about anything and I will try my best to answer here.
Hello Angus,

Can you please clarify what the connection is between WestminsterLab and Lumin? Does the Lumin power amp share any of the Rei's design?

Thanks in advance,
- Bill
 

lscangus

Industry Expert
Oct 24, 2018
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Hello Angus,

Can you please clarify what the connection is between WestminsterLab and Lumin? Does the Lumin power amp share any of the Rei's design?

Thanks in advance,
- Bill
I was asked to join LUMIN a couple of years ago to help them in sales/marketing and some product development. The LUMIN Amp was designed by WestminsterLab. They are very different design in terms of Bias ( LUMIN Amp is only Class AB ), power supply, and also amplification technology. But it was designed with a very similar concept together with the X1. So anytime you see me, feel free to hit me with any questions from both sides.
 

Fred Crane

Industry Expert
Apr 23, 2020
136
254
70
Hello Fred, the Rei can be scaled up in two ways. One is the traditional bi-amping, so you will run two sets of speaker cables individually to the binding post of the speakers. The other way is by bridging two units together into one unit. By bridging 2 units, you will get effectively get 400@8 and 800@4 output. We are currently using this configure with 2 Quest preamplifier ( in mono mode ) in our own testing facility, we did try out a Bi-Bridge configuration with a total of 8 unit of Rei too.
Hi Angus, Thank you for the clarification. I'm wholly impressed by your endeavor. Might I ask which speakers you're using in your lab? I'm curious how you 'voice' your gear, ('purity' is itself a choice).
 

Hear Here

Well-Known Member
Feb 14, 2020
481
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50
Portsmouth, UK
Rei Monoblock Amplifiers: Pure Analog "Class A" power in a Compact Package
Fully balanced from input to output, the REi monoblock amplifier remarkably produces 100 watts per channel of power from an understated and compact chassis. A pair of Rei's are not only easy to handle but also fit perfectly on any standard equipment rack, dedicated amplifier stands, or discretely hidden behind your speakers.

Power to Spare
Each Rei doubles its power with declining impedance, producing 200 watts/channel into 4 ohms and 400 watts/channel into 2 ohms. For those wanting even more power and control, two Rei's (for a total of four mono amplifiers) can be daisy-chained doubling the total available power with zero reduction in sound quality. Vertical bi-application and other combinations are a welcome option.
REI-closeup-front.jpg

Are you really saying that this very small amp is true Class A and can deliver the power you state - 100 - 200 - 400 watts? If so, how does it dissipate the huge quantity of waste heat that Class A amps generate? There's no sign even of a exposed heat sink. Does it use a powerful fan? I am inclined to say "Pull the other one!".

Or perhaps you've found the Holy Grail of Class A amps and designed one that generates no more heat than a Class D - please tell us more.
 

lscangus

Industry Expert
Oct 24, 2018
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Hi Angus, Thank you for the clarification. I'm wholly impressed by your endeavor. Might I ask which speakers you're using in your lab? I'm curious how you 'voice' your gear, ('purity' is itself a choice).
Thank you for your compliment. We have a pair of Vivid Audio Giya G1S2, Penaudio sinfonietta signature, a pair of our own RnD speaker and Apogee Diva
 
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lscangus

Industry Expert
Oct 24, 2018
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Are you really saying that this very small amp is true Class A and can deliver the power you state - 100 - 200 - 400 watts? If so, how does it dissipate the huge quantity of waste heat that Class A amps generate? There's no sign even of a exposed heat sink. Does it use a powerful fan? I am inclined to say "Pull the other one!".

Or perhaps you've found the Holy Grail of Class A amps and designed one that generates no more heat than a Class D - please tell us more.
The Rei deliver 100watt @ 8 Ohm. The idle wattage ( when the unit is warmed up ) is 80watt upwards. Of course with our iBias tech, the bias is slightly reduced when the output is small, but 80watt is not small.

You can see a huge heatsink on the side of the unit ( we did conceal it to make it less ugly and less affected by the ambient sound waves ), and to make the heatsink as efficient as it can be. We designed a custom heatsink profile using finite simulation software and simulation ( how heat is transferred to the ambient air and how air flow is persuaded through the channels ). We have much finer control in how the heat are spreader across the heatsink and make sure the power transistors are working at the same temperature, this also translates to less distortion to the output ( less fighting between each transistors )

The heatsink is good for anything up to 130watt of heat dissipation in a 30'c ambient temperature. We also have a overheat protection which will be triggered when the transistor reaches 70'C.

I have attached one of the results of our simulation on the chassis ( one of the our design iterations )

3.jpg
 

gleeds

Industry Expert
May 29, 2018
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Thanks, Angus. On a less technical note, for size context here are four Rei amplifiers.

4Rei-amplifiers.jpg
 
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gleeds

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May 29, 2018
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Rei monoblock amplifier chassis view with heatsink


1646152233078.png
 
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Hear Here

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Feb 14, 2020
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Portsmouth, UK
I don't buy this. For a true Class A amp of 100 watts into 8 ohms, the heat that needs to be dissipated is normally far more than the apparently pretty standard heatsink in your amp, specially as yours is closed to the side. Also, I'm somewhat suspicious that a true Class A amp of that power (requiring a massive power supply as all Class A amps need), can be as physically small and light in weight as the Rei is.

For example - although these are 2 channel:

Accuphase A75 (2 x 75 watts) weighs 43 Kg / 97 lbs, 260 watts at idle, 520 watts at IEC 60065
Pass Labs XA100.8 (2 x 100 watts) weighs 44 Kg / 99 lbs, 500 watts at idle - they don't dare quote an IEC 60065 figure!

Mono amps are invariable much more than half the size, weight and power consumption of a stereo amp (a pair needs 2 power supplies and 2 cases), so I'm still having difficulty with the Rei spec:

Your Rei (1 x 100 watts) weighs 16 Kg / 32 lbs, 80 watts at idle.

I've not spotted the On/Off switch nor a trigger - surely you are not advocating that the owner of a Class A amp should leave it on 24/7, even if it's burning only 80 watts? Maybe it turns itself off after 10 minutes or so with no signal, though there's no mention of this on the website.

Maybe you're the first Class A designer to have cracked it and can build a true 100 watt Class A amp that's happy with a relatively small power supply, that uses relatively little juice from the grid and ends up in a box the size and weight of many Class D amps. Well done if that's the case.
 

TheMooN

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Jul 30, 2013
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For a true Class A amp of 100 watts into 8 ohms, the heat that needs to be dissipated is normally far more than the apparently pretty standard heatsink in your amp
I found myself wondering about that also, the universal thus far has been the higher the output in Pure Class A Watts the * Larger * the amplifier as a whole, particularly the main heat sinks.
 

ICUToo

Member
Sep 20, 2021
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I think we all need a definition of "Class A" on which we agree.
It hinges on the power dissipation at idle vs rated power output ratio, caused by the resting, constant bias of the output transistors.
Traditionally, I seem to recall that that is about a factor of 3-5 for Class A ie output devices dissipate several times the rated output at idle.
https://www.passlabs.com/technical_article/single-ended-class-a/ has a similar comment re: single-ended class A, which should also apply to other output topologies
 
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gleeds

Industry Expert
May 29, 2018
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Thank you for your questions, all!

In any industry (perhaps especially ours) we consider it a good thing to question presentations of innovation and what any reasonable man or woman could consider bold claims. We understand your skepticism as to the circuit's Class A bonafide and the claimed power output. Angus should be back online this evening PST so perhaps he can add more insight on the subject. Rest assured when I first met Angus I was (shall we say) quite curious myself.

For the moment, please allow me to present another example of Angus's ingenuity from his earlier product portfolio, the Westminster Labs "Unum" Class AB amplifier. The Unum was a product Angus designed and introduced when he was 29 and at the time was considered an even more radical departure from the orthodoxy than the Rei. Who would believe this unpretentious, yet elegant analog amplifier produces 200 watts/channel into 8 ohms, 400 watts into 4 ohms, and 800 into ohms into 2 ohms, and like the Rei was bridgeable for up to 1600 watts into 4ohms?


Unum_7_online.jpg


More to follow and thanks again for taking an interest in Angus's innovations! Gary
 
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gleeds

Industry Expert
May 29, 2018
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Let me add there are on/off switches under the lower edge of the chassis where the logo is.. There are also 12v trigger mechanisms for remote on/off control.
 

Steve Williams

Site Founder, Site Owner, Administrator
I love when someone rethinks the "old way" of doing things. I look forward to learning more ....
Me too

im fascinated that pure class A can come in such a little box but I’ve also heard about some even smaller amps Angus has built which are also pure Class A.
 

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