Rogers made by Audionote E20a RARE! Tube amp made for LS3/5A

Up for sale is a very rare (even more so in the US) Rogers E20a tube integrated amp. This amp was commissioned by Rogers to mate with the LS3/5a, and built by Audionote UK for Rogers. My unit has an inspection date of Feb 14, 1997.

It is set for US operation (110 or 120v probably) even though the back says 220v. I'm guessing it can be converted back to 220v by using different windings on the transformer, but you will need to have a tech try this.

Based on reviews and literature of the time, it was voiced to enhance the LS3/5A, and is, for example, full of Audionote tantalum resistors, which are not commonly available. See the gramophone review I have pasted below.

This amp should be a ‘must-have’ for any LS3/5A owners or collectors.

I have the original box and manual.

I have owned this for 5+ years, but never found the opportunity to put it to good use – I have too many systems, and my main listening room is too large for the LS3/5A. (I used to have a pair of Stirling LS3/5As and Satterberg subs, which I sold before I got the Rogers E20a). I recently finally got a another pair of Stirling LS3/5A V2s (also for sale) to try with the E20s, and the combination sounds fantastic, as would be expected. Having sated my desire to hear the combination, it is time for these wonderful components to find a new owner that will use them (as opposed to hanging onto them due to their quality and hoping to find a use. I tried to convince my wife that we needed a system for the dining room, but that got shot down - the only room still without a system in our house).

I would estimate that I have not used it for more than 20 hours, more likely about 10 hours, of which about 3 is recently with the LS3/5As.

Based on its condition, and the tested strength of the tubes in it, I would venture to guess that its previous owner did not use it much either. All but 1 of the tubes are vintage Russian tubes, and test very strongly in my tester. I did replace 1 of the tubes however when I first got the unit – I really hate the sound of the Russian 12ax7, and I replaced it with one of my favorite 12ax7s – the Shuguang 12ax7c, which to my ears sounds better. I have not tried out the phono section.

It It has 2 minor issues - please see the pictures: a) The top plate front bottom corners are not totally ‘smooth’. I’m guessing that these small bends are from opening the top cover. They can probably be smoothened. b) Upon close inspection, it seems like one of the small capacitors on the main board is developing a slight bulge. As far as I can make out, this is not impacting the sound at all, the amp does sound great. Given that this amp should appeal to collectors, who might want it in original condition, I have decided not to touch it. However, if the new buyer so desires, I will be happy to replace these capacitors with new ones (probably Panasonic FMs). This will entail dismantling most of the case however, and will delay delivery of the unit. Or you can have an audionote dealer or any other competent tech do it at a later time. (I am a mere audio hobbyist).

Other than these, the unit looks great. No scratches anywhere that I have found.

SHIPPING WILL BE EXPENSIVE - IT IS HEAVY. PLEASE BE PREPARED TO PAY IMMEDIATELY VIA PAYPAL. ASK QUESTIONS, ESPECIALLY ABOUT SHIPPING, BEFORE COMMITTING TO BUY IT. BUYER WILL PAY ALL SHIPPING COSTS, INSURANCE, CUSTOMS CHARGES, AND RE-DELIVERY CHARGES, AND BEAR THE RISK OF SHIPPING DAMAGE.
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A response from a reader of this ad, added 3/27/12:

Hi there,
You're right, they are very rare.
I took on the design and production engineering half way through the project.
Rogers comissioned Audio Note to design and supply a fairly high quantity of the 20's and 40's over a three year period but for a variety of reasons, production turned out to be very limited

I remember the specs being very tight, but at the expense of sound quality. The appearance didn't help it much in the European market.
I always liken it to a shaver.
It came out when the CE regulations came in, and one of the requirements was for the valves to be covered, but visible.
The stainless steel perforated top caused us no end of problems because is scratched so easily and didn't dissipate the heat. You'll notice that directly above the valves, the cover gets very hot though that was more of an issue on the 40's
I did like the construction of the main chassis and how the top and bottom fit together and the nice thick textured powder coated finish.
Regards, [name deleted]

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Here are some specs and reviews.

From Rogers International’s web site:

E20A SPECIFICATION

Designed and built for digital era, the Rogers E-40 and E-20a Class 'A' Stereo Integrated Amplifiers truly represent digital sound the way it should be heard and appreciated.

These superb fully integrated, all-valve, handmade amplifiers are guaranteed to send tingles down the spine of the most discerning of audio aficionado's. Recommended for use with a wide range of the highest quality transducer or electrostatic speakers. When partnered with Rogers' LS3/5A and AB1 speakers, the result are truly spectacular!

The E-20a is recommended for smaller listening rooms using standard transducer speaker systems.

"The merging of digital and valve technology is the perfect marriage between source and loudspeaker"

Power :

20 watts per channel class 'A'

Valve Output :

Push Pull Cathode Follower
Self Bias 6L6GT x 4

Phono Stage :

2 x ECC83/12AX7

Line Input Impedance :

Phono: 47K ohms, Line: 100K ohms

From gramaphone dot net, July 1996

Rogers E-20a integrated valve amplifier

A roll-call of famous British valve amplifiers of yesteryear would without question include the Williamson, Quad II and Leak Point One, but probably not the diminutive Rogers Cadet. Though this popular little amplifier evolved through three generations, and was more highly regarded by many than its large stablemate the Master, it never quite entered the hall of fame. So Rogers' two new integrated valve amplifiers, the 40watt E-40a and its 20-watt E-20a sibling reviewed here, could rightly be said to continue a tradition but hardly be accused of exploiting it. In the Rogers brochure, indeed, no mention whatever is made of the new units' forebears.

The idea of a reborn Rogers valve amplifier first occurred to Andy Whittle, the company's resident loudspeaker designer, about four years ago, but for various internal reasons did not win the necessary support. At that point the project might well have languished but for the perseverance of Peter Qvortrup, the man behind Audio Note UK. A fan of the Cadet, and a vociferous proponent of valve amplifiers in general, he stated and re-stated his view that Rogers should get back into the valve amplifier business. This drip-drip-drip of incitement was eventually rewarded when the project got the go-ahead.

A resurrected Cadet, though, would clearly not meet today's requirements. Rogers acquired one and liked its sound, but knew very well that 10 watts (the rated output of the Mk Ill) would not suffice to drive the 86dB sensitivity Rogers loudspeakers with which it would have to work. For the same reason one of Qvortrup's favoured all-triode designs, be it push-pull or single-ended, was out of the question too. As Whittle puts it, "We were not about to design a 95dB sensitivity, paper-coned loudspeaker to make our amplifiers work". So Rogers specified outputs of 20 and 40 watts respectively for the two models and passed development of the circuits over to Audio

Note, which also manufactures them on Rogers' behalf.

Whittle was involved in the final 'voicing' of the designs, and makes no bones of the fact that they were specifically tailored to inject more life and colour into the sound of the LS3/5A and Studio 5 and 7 loudspeakers. Strictly, then, the E40a and E-20a were not created as 'universal' products but as tools for a specific task. While that does not mean they won't work well with other loudspeakers, it does counsel that they were not created with neutrality foremost in mind.

Price and power constraints meant that both the E-20a (f 1,090) and E-40a (l,900) would have to use pentode output stages, the chosen valve being the 6L6GT. In the E-20a a single pair of these devices is used per channel; in the E-40a, with its doubled power capability, output devices are paralleled to raise the total complement to eight. Up to (almost) their rated outputs, both amplifiers operate in Class A.

Ultralinear connection of the output valves, with the screen electrodes connected to taps on the transformer primary (an arrangement patented in the early 1930s by the redoubtable Alan Blumlein), might have been expected since it is widely held that this represents the best way to operate a power pentode, endowing it with a share of the desirable qualities (lower distortion, lower anode resistance and better tolerance of load impedancevariations) which distinguish the triode. But Qvortrup - no respecter of convention - prefers pure pentode operation. "It sounds better when there is only one, overall feedback loop," he says. "You lose quite a lot of bass and definition with ultralinear."

Elsewhere the E-20a (like the E-40a) uses triodes exclusively, sourced, together with the output pentodes, from Russia. An important criterion in selecting all the valves was that they be in current manufacture and hence likely to remain readily available for years to come. Including its four output devices the E-20a sports nine valves in total (two of which are tucked away on a separate circuit board), but a simple glassware count is misleading since all the triodes are double triodes -effectively two valves sharing a single envelope and heater.

Line-level inputs are routed straight to the power amplifier board-via the source selector, tape monitor switch and volume control-where half an ECC83/ I 2AX7WXT per channel, connected as a simple anode follower, forms the first gain stage. Further amplification and phasesplitting is thereafter provided by two halves of a 6SN7 connected in a paraphase circuit, whose anodes drive the grids of the output valves. Both gain stages have their HT rails separately decoupled from that of the output devices which, as one would expect at this price level, are cathode biased to obviate the expense of a separate bias supply. A modest 10dB or so of loop negative feedback is taken from the output transformer sec ondary back to the cathode of the input ECC83.

The remaining pair of double triodes, again ECC83/I2AX7s, form part of the movingmagnet phono input stage, which occupies its own small circuit board. Each valve divides its duties between the two channels, the first providing input buffering and sufficient gain to feed the passive RIAA equalization network, while the second - also connected as a simple anode follower - ensures sufficient overall gain to drive the power amplifier. Additional resistor-capacitor filtering for the HT of each stage cuts hum levels, while unbypassed cathode resistors provide a measure of local negative feedback to stabilize gain and reduce distortion.

All told it amounts to a pretty conventional, unremarkable-looking circuit design. But care has been taken over operating points to ensure both longevity of the valves and maintenance of sound quality, and lesser examples of Audio Note's audiophile-grade resistors and capacitors are used throughout. As with all transformer-coupled amplifiers, the quality of the output transformer also plays a significant part in determining overall performance. Distortion levels are, inevitably, an order of magnitude or more higher than you would expect of a solid-state alternative - particularly towards the E-20a and E40a's somewhat optimistic rated outputs - but then the modern valve amplifier renaissance was never about blameless performance on the test bench.

It wasn't about svelte good looks either. The creators of valve amplifiers generally appear to revel in unadventurous, laboratory equipment styling, as if anything more attractive might suggest non-seriousness of purpose. Not so with the Rogers units, which express a bolder aesthetic. Their appearance design is the Specification work of Graham Allen, an independent industrial designer who lists other valve products in his CV.

Realizing the now-obligatory valve cage as a curved sheet of perforated stainless steel - looking for all the world like the head of an electric razor in close-up -was an inspired idea, but unfortunately it suffers somewhat in the execution. Surface finish on the review sample was poor in places, while attachment of the sheet's rear edge by three exposed buttonhead socket screws frankly looks unprofessional. I also think the whole effect would have been enhanced - particularly with the use of bright-plated control knobs on the front panel - had the main body of the amplifier been finished in gloss black rather than cracklefinish grey, an echo of past practice which looks out of keeping with that bold sweep of stainless. I also couldn't help noticing that the knob of the balance control stood proud of the other four (Tape Monitor, Source Selector, Volume and Power) because it had not been seated far enough back on its shaft; a small detail but just the type of imperfection that detracts from a product's air of professional competence.

Three line inputs are provided (Line I, Line 2 and CD) together with Tape In/Out and Phono, all via gold-plated phono sockets. To allow closer to optimum matching with loudspeakers of different nominal impedances, two output taps are available via terminal posts: one for loudspeakers of 4 to 6 ohms, the second for loads of 8 ohms or higher. The non-standard Rated power output 20 watts per channel, Class A Matching output impedance 4, 8 or 16 ohms Input sensitivity Line level 1 5OmV; Phono (MM) 5mV Input impedance Line level 100k ohms; Phono 47k ohms Phono equalization Anode follower, passive RIM Dimensions x H x D) 430 x 175 x 430mm Weight 17kg - Manufacturer Rogers International Limited, 310 Commonside East, Mitcham, Surrey CR4 1 HR. Telephone 0181-683 2101 UK retail price £109000 dimensions of the amplifier175 x 430 x 430mm - mean that it will not readily fit many equipment shelves but that may be no bad idea since, like most valve equipment, it requires free passage of ventilating air up through the slots in its base.

Performance

Although I have been critical in the past of the spurious justifications commonly and carelessly offered up for the 'superiority' of valve amplifiers, I am in fact a long-term user of valve power amplification myself. For some years it has taken the form of Audio Innovations' all-triode First Audio Amplifier, in whose creation Qvortrup coincidentally took no small part. Although the First Audio cannot match the E20a's output capability (even using the Wilson Benesch Act One loudspeakers, which are pretty sensitive, it will occasionally clip on stressful programme like soprano voice) and is appreciably more expensive, despite being a power amplifier only, it nevertheless formed a handy and appropriate point of reference during my listening.

If 'the valve sound' stands for anything it is an open, inviting sound quality which brings you closer to the performers and their performance. This is what attracts me to the First Audio and, ironically, what distances it from many other valve amplifiers of my acquaintance which, thermionic hype notwithstanding, have actually diluted musical communication by putting too rosy a glow on everything.

The E-20a, thankfully (though not surprisingly knowing its origins), is not of this euphemistic school. It has the openness and directness with which to attract listeners who enjoy the savoury flavours of music as much as the sweet. Though solid-state, amplifiers typically sound tidier, more overtly in control, it's a not uncommon reaction that, in the longer run, they also sound some what sterile. Whether you agree with this contentious generalism doesn't really matter: the significant point is that a good valve amplifier, like the E-20a, offers an alternative view - one which a significant number of music lovers apparently prefer.

I'd be misleading you, though, if I were to suggest that the E-20a embodies anything like the ultimate expression of these characteristics. It may be overly simplistic to blame its pentode output stage, but there's no denying the Rogers concedes something to the all-triode First Audio when it comes to stripping back obfuscations. Playing the elegiac Aria from Panufnik's Bassoon Concerto (Robert Thompson, London Musici/Mark Stephenson Conifer CDCFI82, 7/90), for example, I was aware of listening to something more like a generic bassoon sound via the Rogers, whereas via the Audio Innovations the instrument took on a distinct and individual character.

Such invidious comparisons aside, the E-20a makes a good sonic impression (through its line inputs, anyway- unfortunately I was unable to try the phono input). It possesses the smooth, expansive sound for which valve amplifiers are fabled but retains sufficient powers of analysis to be informative as well as emollient. It has that happy knack of sounding balanced and self-consistent so that, even though it tends to softness in the bass and is not the last word in resolution, these failings are not thrown into undue relief. Partnered with moderately sensitive loudspeakers and not asked to raise the roof, it also has just enough power to keep out of trouble.

In its allotted role of stirring a little 'pizzaz' into the sound of LS3/5As, the E-20a will surely find a welcome worldwide - particularly as it carries the Rogers name. It would be a squandering of the Cadet successor's talents, though, were that its only application

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Here is another review of the e40a

Designed and built for digital era, the Rogers E-40 and E-20a Class 'A' Stereo Integrated Amplifiers truly represent digital sound the way it should be heard and appreciated. These superb fully integrated, all-valve, handmade amplifiers are guaranteed to send tingles down the spine of the most discerning of audio aficionado's. Recommended for use with a wide range of the highest quality transducer or electrostatic speakers. When partnered with Rogers' LS3/5A and AB1 speakers, the result are truly spectacular! The E-20a is recommended for smaller listening rooms using standard transducer speaker systems. "The merging of digital and valve technology is the perfect marriage between source and loudspeaker"

Power : 40 watts per channel class 'A'
Valve Output : Push Pull Cathode Follower
Self Bias 6L6GT x 8
Phono Stage : 2 x ECC83/12AX7
Line Input Impedance : Phono: 47K ohms, Line: 100K ohms

Of all the many subjects discussed in the LS3/5a yahoogroups mailing list, the subject of which amplifier to use with the LS3/5a has been the most controversial. A look through the group database shows members using Quads ancient and modern, old Leaks, Radfords or modern M.F. Nuvistors, the list goes on and on. If there is any consensus at all it is that the LS3/5a sounds terrible with some solid state amplifiers. Many of the group members think LS3/5as should only ever be driven by tube power.

I was intrigued then when Doug Stirling from Stirling Broadcast rang me to offer the loan of the Rogers E40a. This amplifier's pedigree is impeccable. It was designed and manufactured by none other than Audio Note for Rogers UK before they went belly up (Rogers that is). Doug bought out Audio Note's stock and has been steadily selling them to happy customers ever since, several of whom lurk in the LS3/5a mailing list. But what's especially interesting is that Rogers had this amplifier in mind as the perfect companion for the LS3/5a and AB1. To quote from the brochure, "Recommended for use with speakers that have an efficiency of around 86dB and, when partnered with Rogers' LS3/5A and AB1 speakers, the results are spectacular."

OK, so that's advertising copywriter's hype but then Rogers certainly knew what they were about and their early version of the LS3/5a remains among the most sought after. I used the E40a in my system for more than a month before Doug managed to prise it back off me. First let's get the technical stuff out of the way
The E40a uses a quad of 6LGGTs in each channel to generate 40 watts of Class A power into an 8 ohm load. In a Class A amplifier the output devices, tubes in this case, are biased so that they conduct continuously. There is no change in tube plate current with signal. Class A lovers say there isn't any other way an audio amplifier should work. The trade off is inefficiency. A Class A amplifier runs hotter when it is sitting silently than it does at full pelt. And does the E40a run hot! 40W of Class A is a substantial amount of power and in order to be able to generate it the 8 output tubes alone are going to need to dissipate at least 160W of heat at idle. In practice the E40a pulls a little under a continuous 300 watts out of a 240V mains supply.

The choice of 6L6GTs for the output stage is interesting. This tube was originally designed with the military in mind and modelled on the physically bigger and now horrendously expensive KT66, beloved of Quad II owners. The rest of the tube line up includes ECC83 line and phono stages, an ECC82 phase splitter and 6SN7 cathode follower.

Unbalanced inputs, on gold plated phono sockets, are provided for a phono cartridge, dedicated CD input, 2 line stages and a tape deck. Line level tape output is catered for. Speaker output uses very nice Audio Note gold plated binding posts to take either 4mm plugs or thick bare wire ends. Output transformer taps are provided for 4 and 8 ohm loads. What a shame a 15 ohm tap wasn't provided for the owners of old LS3/5as run sans AB1s. The E40a will drive them OK if the speakers are connected to the 8 ohm tap but the full power of the amplifier won't then be available.
As for the aesthetics? Well I have to admit that I like to see tubes sitting proudly above the chassis glowing merrily. For me, a Quad II is the model of function leading to pleasing form. And I even like the rather industrial look of the Leak tube amplifiers. In the E40a the tubes are mounted on a printed circuit board at the bottom of the black chassis, the top of which features a curved stainless steel perforated cover which was the subject of much comment by visitors. My wife drew an instant comparison with the UK Millennium Dome (how cruel can you get) but for me I'm afraid the E40a looked extraordinarily like an aerial view of a main line railway terminus! Unfortunately you can't run the amplifier with the cover off because it exposes high voltages on the board. And those knobs! Gold-plated with the control legends written on the stainless steel cover. The E40a does look much better in the dark, where the satisfying glow from those eight 6L6GTs will be a fine substitute for someone who hankers after a real fireplace.

The E40a is a big amplifier. Although only a shade wider at 430mm than a full-width CD player it is as deep as it is wide. This could cause a problem for an owner with an equipment rack although if you don't mind it hanging over the back some Vibrapods or similar will allow it to sit on the top shelf. It is also heavy, weighing in at around 20kg. I didn't have a support that was suitable and so ended up with the E40a on my wooden floor. Realising this isn't ideal and conscious of the information in the instructions about using a decent support, I experimented with vibration isolation putting home-made Silipads (silicone rubber pads), bean bags and juggling balls under the amp. Curiously all of these degraded the sound achievable by simply using the E40a's own feet. Tube amplifiers, because of their inherent microphony, are often more critical of what they stand on than solid-state amps, and this was the case here. It would certainly pay an owner to spend some time experimenting.

All tube amplifies need a long warm up period and the E40a is no exception. This amplifier sounds best when it is really hot! No problem there because that's just how it is designed to operate, the instructions caution about how hot the stainless steel cover gets and although I didn't try it because I thought Doug would object to the crumbs, I'm sure you could toast bread on the top!
After about an hour of warm up I couldn't resist the temptation any longer and put on a CD. In the past I have used Quad IIs and old Leaks and consider myself fairly familiar with the sound of tube driven LS3/5as. My particular favourite are the Quads which have been described as a marriage made in heaven when used with the LS3/5a. Although the Quads don't appear on paper to have enough power output to drive the LS3/5a-AB1 combination properly, in practice they can go satisfyingly loud. It's all due of course to Peter Walker's marvellous conservative design and the intrinsic ability of tube amplifiers to sound nice as they are driven into clipping.

I wasn't at all prepared for what I heard from the E40a. It was immediately clear that the E40a is a very good amplifier indeed. But it sounded nothing like the cuddly warm soft clipped sound I know from Quad IIs. Neither did it sound like my solid state amplification, modified Quad 405-II or home-made MOSFET amplifiers. The E40a sounded much better, rather like a very, very good solid state amplifier. Had I been listening blind I would have guessed that I was listening to some very classy and very expensive well-behaved solid state amplifier. Perhaps the giveaway would have been the just slightly light bass, although that got better and better as the amplifier got hot, "warmed up" seems an understatement here.
Then the penny dropped. I was listening to a modern tube amplifier. Not an old Quad or Leak. This amplifier was transparent. Forty watts of modern, pure Class A tube amplification with no added vintage tube extras. In many ways it does exactly what the LS3/5a does so well. The midrange was clear and analytical, so clear that I was able to understand vocals I had previously missed on well-known CDs. The stereo image was pin-sharp, very wide and deep.

I was so impressed with this amplifier that when Andrew Drummond, Derek Rumble and I ran the LS3/5a demonstration room on behalf of HiFi News at the 2001 London Show we chose the E40a as our amplification. Andrew loaned his own E40a for the show and it behaved flawlessly. Despite all the attempts of the desperately poor acoustics of our Novotel Hotel room we were able to throw up a convincing sound stage for the visitors. And the visitors were clearly impressed with comments like, "the best sound in the show" written in the vistors' book.

If there are any E40as left at Stirling by the time you read this (and I am sure some will have sold as a result of our activities at the HiFi Show) then a brand new E40a can be had for very much the same price as a decent set of Quad IIs. The choice is yours. Would I own one? Absolutely! Why don't I own one? Well only because, as an incurable romantic I'm looking for the right set of Quad IIs to come along. The problem of course with owning a vintage amplifier like the Quad is that you had better be able to fix it yourself. Because if you can't, then just like running an old car, you are going to be faced with frequent big bills from the repairer. My heart told me that I wanted to use Quads at the London HiFi Show. My head told me that it would be madness. To a rational rather than a romatic the E40a is actually a better amplifier and won't surprise you with the bangs, pops, hum, whizzes and farts that so often add to the listening experience of vintage tube amplification! The E40a will work when switched on and will go on working.

The E40a sounds great, generating a huge holographic sound stage. Forty watts of great Class A tube sound at a bargain price, what more could you ask for?