Westminster Labs REI Mono Amps Eval
 

In case you are not familiar, Westminster Labs REIs are mono amps.

https://www.westminsterlab.com/rei

The are relatively small and light weight Class A amps. Into 4 ohm speakers, such as our Magico M3s, they deliver 200w of Class A and if I bridge another set they will deliver 800w of Class A.

We will hopefully begin our demo eval this coming Friday. We will have them for app a week. We will post pics when they are delivered.

After this eval we are doing one more demo eval. That eval will be for the brand new model of BAT amps (solid state). We will only have a stereo amp in for eval, but if we enjoy them “more” than Pass and the REIs then we will be purchasing the mono version.

Here is what Westminster Labs website states:

Built Like No Other

Stability and rigidity of the whole amplifier is one of the key criteria to a outstanding amplifier. This is because under a stable environment, signals and power can go through a more stable, undisturbed flow. For that, the chassis must be very stable and rigid with very low resonance and vibration.

Rei’s concept of mechanical structure is completely different from UNUM, instead of just having one unibody like UNUM, the main load bearing chassis of the Rei amplifier is constructed with two very rigid CNC machined aerospace grade 6063 aluminium components.

Why two? Because we can separate the mechanical vibration between power supply components and the “amplifier” electronics. From our test, we realised the power supply has a micro-mechanical vibration at the power supply frequency and its harmonics, which is very different from other electronic components within the amplifier. And this unique construction media this phenomenon to the minimum.

The exposed exterior panels of an amplifiers absorbs a lot of micro-vibration within the audio-band from the speakers. Hence these external panels of Rei are designed to have resonance as furthest away from the audio-band as possible and anchored to the power supply chassis, away from the delicate and sensitive audio electronics.

Asymmetric Heat Sink Design

One of the main components of the chassis where all the “amplifier” electronics are mounted on is the main heatsink. It is a very challenging components to engineer, as it has to function as a structure, means it has to have certain mechanical stiffness; it also has to function as a heatsink, which it must have a certain degree of exposure to the environment and this creates a problem as the sheer surface area, which is needed in order to function as a heatsink, can have a significant effect on the sound as it is a massive sound absorber.

That is the reason why the heatsink of Rei has a very unique asymmetric fins, which reduces the resonance effect, and the aperture of the heatsink is controlled by other body panels to make exposure to audio vibration as least as possible.

Not The Typical Class A

The Rei employs a WestminsterLab proprietary iBias and CCS systems, what it means in terms of electronically. The Rei will warm up much faster than other typical Class A amplifier, and the iBias technology constantly varies the bias depending on the current and also the loading of the amplifier. And the result sonically, is you get the best of the Class A without the typical draw backs. Is truly unique.

A new page in transistors matching

Matching transistors are not uncommon in the world of amplifier design and manufacture. But WestminsterLab do it very differently.

Not only the transistors are matched within 1%, the*matching and paring are done across several working points of the curve and*stress tested for hours to ensure the transistors are matched under extensive load.*This is also*one of the very reason why we can deliver 400 watts of Class A power in such a small package.

Is all about POWER

The power supply design is one of the key elements in amplifier design. Lots of users or even manufactures completely underminds*the importance of a capable power supply. Not only the power supply has to be low noise ( both voltage and current ), it has to be able to maintain those characters under loads. The speed that the power supply reacts with a sudden surge of load is also key to the intoxicating instant oomph that the Rei able to deliver.

Ultra thick PCB

The PCB is one of the key components within any amplifiers. It is the medium amongst different components, this network of complex copper connection can somehow be the weakest link within the equation if it is to be overlooked. After years of testing and countless prototypes with our supplier, we have nailed a certain type of PCB with ultra thick and ultra pure copper layer. In our own audition, it is pure, fast and transparent, it came very close to point to point soldering.

New demo amps on schedule for tomorrow. I’ll post some pics later in the day.

Looking forward to seeing them, as well as your impressions.

These speak of quality. From the non-magnetic screws that are used to put them together to the Aerospace Grade 6063 Aluminum of the chassis. It’s of the highest quality. The carbon fiber on top of the amps matches the sides of our M3s. It’s beautifully done. Nice touch.

From what I was told the warranty is reportedly 5 years. Their online manual is rather extensive - https://www.manualslib.com/manual/21...page=23#manual

They are light weight, which is unusual for most amps of this caliber - esp. in Class A. They get warm (but not as warm as our Pass 260.8s), but definitely not hot.

Set up is rather elementary. They are ready to play Class A out of the gate. Initial warm up time is seconds, but you have to wait 45 minutes to an hour or so to begin to get the full impact of what these amps can deliver. Having a second set bridged (800w Class A into 4 ohms speakers) would be very nice!

Our listening impressions will come later. But they are sounding very nice.

Pictures of Installation and Final Placement. Some pics with the Pass 260.8s reveals the size of these “small” Class A amps.

And they match your other components perfectly

Yes they do! :banana:

Initial Listening Impressions

They’ve only been on for 8 hours, but Westminster Labs REI Mono Amplifiers are the best amps we have ever heard. I didn’t think such was possible with such a light weight small Class A amp, but apparently it is.

We’ve pretty much all witnessed speakers disappearing, and even amps doing the same. However, with REIs even your walls disappear. These amps are absolutely amazing.

REI’s are very accurate, while retaining musicality. They have it all; presence, smoothness, texture, and immediacy. Play whatever you desire there’s no strain on these puppies. Love the way they control the low-frequency info (takes app 6 hours to come into full bloom - we leave the amps on). The music sounds deep and wide; they present a soundstage that’s off the charts. Excellent.

The REI’s have their own Class A signature sound. It’s unique. I’m not sure which other high end amp, that I’ve heard, they sound most similar too - perhaps Soulution 701s plus a touch of tube goodness. One audiophile has reportedly replaced their MSB amps with the REI’s. And another their DarTZell’s.

They produce a powerful beautiful Class A sound. Two audiophiles visiting today we’re also amazed.

I’m not sure yet if these are “the” ones for us, but they are exceptional. This said, we still need to hear the competition = BAT. This is their brand new amp that we will be hearing in about a week. We are also considering Audio Research 160M monos.

Thanks for sharing Joe - I’m amazed at their small footprint! Sounds like you’ve got a fight on your hands with these, the BAT’s and EMM Labs all being serious contenders

Thanks. I think it will be a difficult decision. At this level it will be more a matter of taste then better, best and just ok.