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Concordant Excelsior Preamplifier

What's New Pussy Cat?

[What's new pussy cat?]
"Harmonious Realism", replies Doug

[Italian version]

Product: Concordant Excelsior Preamplifier
Approximate cost: rare used, was 825 when introduced and 1140 when production ended (see text)
Reviewer: Mark Wheeler - TNT UK
Reviewed: July-September 2005 (and 1987-1991)

For as long as I'd been interested in hi-fi I'd been vaguely aware of some little advertisements in the HiFi News & Record Review classified ads section, offering: Quad II valve amplifier modifications promising "almost 25W" and SME 3009-II gimbal pivot vertical bearing conversions. Then one day in the mid 80s I was sent to visit Doug Dunlop by Derek Whittington (proprietor of Sound Advice in Loughborough) when my friend Flat needed his Quad IIs serviced. It transpired that Doug was the man behind the little adverts and many years evolution of valve amplifier modifications after a career with British amplifier manufacturer Leak. We spent an evening at his house learning about the preamplifiers he was developing and he retained Flat's Quads, refusing payment, and invited us back again next week, ostensibly to collect them.

On our return we were shown a pile of little boxes of ECC83 valves of various vintages & brands and asked if we could describe their different sounds in a prototype preamplifier. We had never, until that moment, contemplated that different brands of elderly valves could sound different. I had only thought about my valves when they needed replacement. A couple of years previously, I had walked into a local tv, radio electrical spares store (the kind where everything is behind a counter patrolled by men in brown coats) and asked for a set of four KT66 valves please. The man in the brown coat reappeared with four original boxed GEC KT66 and then converted the old English sterling sticker price (pounds, shillings & pence used in Britain before February 1971) into modern decimal money (.p) and charged me that amount! He said "You're the first person who's asked for valves in over 15years". I had been pleased to be able to find any old valves, but now Doug Dunlop was telling me that different brands sound different. The first of Doug's paradigm shifts to my thinking, but not the last. Doug described the differences between Mullard, Teonex, GEC and modern types like Golden Dragon or Groove Tube as "Night & Day" and liked to mix brands to produce a sound that balanced the virtues of each type.

Doug also played us an Audio Research SP8 pre-amp which we had previously only read about. At that time Audio Research were as exotic and legendary to us provincial Brits as Japanese high-end single-ended amplifiers driving active arrays of horns and Onken tweeters. Doug told us that the Audio Research SP8 was the best commercial pre-amp he had heard until that time but that he knew he could, and had, made better. Doug admired the SP8 and paid homage to it by his own unconventional rear panel layout (which mystified British reviewers who were irritated by the right channel sockets on the top-row and left channel on the bottom-row). Doug tended to measure his own products by how much they could better the SP8 (and later an SP11 as benchmark too) and keep his price well below the imported competition.

Doug's resented the levels of mark up demanded by some high-end distributors to give new manufacturers some exposure in the marketplace. Doug didn't like to charge more than the cost of manufacture plus a reasonable profit. He didn't enjoy any of the business aspects of audio manufacture and relied on his wife Sylvie to keep an eye on things. Typically Doug came up with the unconventional idea of the Concordant Music Club. This would be a network of enthusiasts who were willing to demonstrate Concordant products to potential customers in their own homes in exchange for a modest commission. Flat and I became demonstrators in Derby, giving us the opportunity to invade people's houses and compare other people's systems. We had expected to be blown away by high-end exotica but were usually shocked and disappointed at the mediocre racket pouring out of some very expensive electronics. There was never one single occasion that the resident preamplifier was better than whichever Concordant model we played. People were, however, reluctant to buy the Concordant because it lacked the street-cred of a long history of rave reviews, a fancy fascia and established dealer network. We never sold one despite their obvious audible superiority to the established competition; customers seemed to buy on appearance just as they eat with their eyes.

Initially the Excelsior was priced at 825including taxes but gradually rose to 1140 to include a solid hardwood sleeve and other improvements, which was still a lot less than the imported competition. The Excelsior earned a couple of excellent press reviews 'Recommended' by HiFi Choice in December 1989 and by Ken Kessler's in his 'Headroom' column in HiFi News the same year. The Concordant prices were comparable to the contemporary Naim NAC42 or NAC32 pre-amps plus Naim SNAPS 24v power supply, which were two of the British press favourites at that time. Concordant pre-amps were available in maroon (with gold lettering), blue (with silver lettering) or black (with either gold or silver lettering) and looked more quaint in the atmosphere of the 80s than they do now in this postmodern age.

All the phonostage equipped Concordant Premier Tube Range featured "Super A" outboard power supplies. Doug described the Super A circuit as "a kind of electronic petrol supply". The circuit principle had first appeared in his modified Exultant Quad II where the GZ37 rectifier valve was replaced by a solid-state bridge rectifier followed by a power tetrode regulator. In the Concordant Exultant Quad IIA the choice of "Super A" valve had more effect on the sound than the valves used in the output stage. Even though the output stage featured EL34, the sound of the amplifier was very familiarly Quad-like when a KT66 was used in the "super A" socket (where the GZ37 used to live), but could sound more like an Audio Research with a 6550A in place. The Excelsior's Explicit Super A power supply uses a 6CG7 after rectification & smoothing by solid state. The 6CG7 is a medium-mu double triode designed for TV vertical deflector applications and features a controlled warm-up time, which has longevity benefits in this application in the Concordant power supply, applying the HT long after the heaters have warmed. TV deflector valves are now becoming popular as rectifiers with the high-end DIY fraternity for their superior noise performance compared with conventional diodes.

The Super A outboard power supplies probably contribute to the very low noise-floor of the whole Concordant pre-amplifier range, lower than most valve products of the day. HiFi Choice measured hum & noise -108dB, which they described as "spectacular".

[6CG7_among_the_caps]
Explicit Super A power supply

The Excelsior was a very different cat from the Exhilarant and Exquisite models that both had a more sophisticated line-stage. The Excelsior uses two E83CC (an upmarket ECC83 or 12AX7) and an unusual GE milspec 5965 (some Excelsiors use ECC85) in the phono stage and two further E83CC in the line stage. The 5965 is an unusual twin-triode designed for use in computers and features completely separate cathodes ensuring lower crosstalk than many types, maintaining similar inter-channel crosstalk at 1kHz as the dual-mono linestage. There was briefly an Exultant model in the Premier Tube Range (lacking the Excelsior's 5th triode in the phono section), designed to provide an entry level Phono preamplifier to match the well known modified Quad II power-amplifiers that were also marketed as Exultant when they reached their final incarnation:

Both the Exhilarant (line only, final price 900) and Exquisite phono+line (final price 1950) used what Doug Dunlop called the "DC Repeat" line-stage, whereas the Excelsior features one ECC83 before the volume pot, rather than the more common practice of locating the volume pot between the input selector and the line gain stage. In this respect the Excelsior resembles a passive control unit with the potential for problems with long or reactive cables, although no such problems occurred with my 6metre interconnects. The 5volt output capability (the Excelsior can deliver over 30V if more than 1% distortion can be tolerated) probably helps overcome the high output impedance which can exceed 8kOhm at certain volume settings.

During it's production lifespan the Excelsior underwent a number of revisions. Many of these were in response to feedback from customers and dealers, but Doug never ceased trying new combinations of valves or tweaks to the circuit. The final iteration dispensed with the conventional rotary mono switch and balance control, and it featured two line-level controls (designated 'input level') in their place. The earliest versions lacked the ambiguously named 'bypass' rotary selector, having a conventional 'line-mute-phono' selector. The 'bypass' control was one of Doug's innovations to provide the most direct signal path for the dominant source (lp on the Excelsior), but it also (on some versions) allows the owner to vary the amount of negative feedback on the line stage, the "high" position selecting less feedback (i.e. higher gain). The odd number of gain stages means that this pre-amp inverts phase, so purists should reverse speaker connection, but I find few recordings demonstrate a preference either way.

[best_lid_off]
Neat interior layout

These preamplifiers break many twenty-first century high-end hegemonies. Doug Dunlop eschewed audiophile passive components (he simply refused to try them) and specified established good quality commercial grade components. All Concordant pre-amps apply now-unfashionable negative feedback round the line stage. The Excelsior uses an active feedback based compound RIAA equalisation from the output of the second ECC83 to the cathode of the input ECC83. Modern purist trends favour completely passive RIAA equalisation and often split either side of an extra gain stage to minimise interaction between the 75uS (2122Hz) and 318uS (500.5Hz) filter sections. The Concordant RIAA equalisation was never designed or manufactured to be perfectly accurate at the expense of complexity or beauty. The RIAA EQ is flat from around 15Hz to 200Hz, then rises gently to peak 1.5dB higher near 10kHz before gently rolling-off with a familiar low-pass slope to be 6dB down by 50kHz. Doug described his circuit arrangement as "high invert phase", and believed it to be more similar to modern transistor designs than traditional text-book valve circuits.

All the Concordant preamps take the tape output from the final stage. Doug noted that this made it possible to get the tunes of your Concordant front end in your car. It also means the tape output is buffered after the tape input, so be careful with the monitor switch on tape decks with a shared record-playback head, and be ready to use your 3 head Revox as an echo machine (whatever happened to the WEM Copycat?). I never heard Doug use any source other than Vinyl, usually a Source Turntable; Odyssey Arm and Decca London Gold cartridge. Mike Moore, designer of The Source turntable was a friend of Doug and there were regular evenings at Doug's house listening to potential modifications and persuading Doug to play something other than Johnny Cash records.

Doug used a pair of my speakers alongside a pair of Steve Margolis' Seventh Veil speakers in his demonstration room at the Chesterfield HiFi Show one year. That weekend I had the opportunity to hear production versions of each model of preamp through the Exultant IIA power amps. The very transparent Seventh Veil (line sources of four Bandor 50mm units without crossovers, with a transmission line concealed in the steel stand) or through my own familiar speakers with Decca London Ribbon tweeters. The Seventh Veil were surprisingly similarly voiced to my 100 litre behemoths. Between these two speaker types every nuance of performance became very familiar, as did Doug's choice of records (too much Johnny Cash again). That hifi show favourite Jazz at The Pawnshop was played many times that weekend, and it became increasingly obvious to me that the Excelsior was the star of the range. While the more expensive Exquisite exhibited more high-end gloss and more impressive soundstage, the Excelsior had far more pace, better timing and more coherent rhythm. Several showgoers made similar observations and I know some orders were received on the strength of the show performances.

Doug's next project was the 100wpc transistor amplifier Exemplar "with the sound of valves". In 1993 my first son was born and my then wife continued to work nursing shifts so I became his principle carer, as professional childcare could be matched with my normal working hours. This interrupted my relationship with Doug Dunlop and Concordant. Within a couple of years I was hearing rumours that he had become ill and could no longer make the preamplifiers. There were attempts to find a local alternative manufacturer (including one ambitious plan to repackage the products as truly high end) but all came to naught. I was unable to contact Doug's wife Sylvie to learn of Doug's health, and eventually word reached me that he had died.

[Mark's_marks]
Mark's panel marks

The sound now

Mark Orr, designer & proprietor of Something Solid equipment racks was a fellow member of the Concordant Music Club and still has his original Excelsior which he is kind enough to loan to me. The deep maroon finish has suffered some patchy discolouration and is beginning to look a bit mauve in parts. The input selector switch has intermittent faults on the right channel causing it to semiconduct at times and cut out altogether sometimes. Because the bypass switch does just what it says on the front panel, this is not a problem on vinyl. After so many years I wonder how the Excelsior will compare to modern standards. Mark has the standard steel cover, but Doug had demonstrated to me the superiority of use without the cover, or better still the 100 Iroko wooden sleeve that eventually became standard on all models.

The liveliness and pace I remember is still there aplenty. Aural memory is notoriously unreliable (partly because of the way hearing works and the way the brain writes & retrieves) but the aspects of performance I found most impressive about the Concordant Excelsior are still there in spades. It still sounds much better without the lid, another Doug paradigm shift that led to my box clever experiments.

I dug out the lps I was listening to in the late 80s including Latin Quarter's Modern Times. I was introduced to this lp by Doug (when he wasn't playing Johnny Cash). Modern Times has varied production, bizarre microphone eq, excessive reverb, but catchy 80s pop tunes and well written overtly political lyrics (that coincide with my politics & reinforce my prejudices) and sounds through the Excelsior just as I remember it. Unusually tight bass for an older valve design, bouncing along like a Naim or Exposure. Instruments are easily individually perceived and followed. Herbie Flowers double tracked bass on Lou Reed's Walk On The Wild Side is as clear as my hotrod Naim.

Little Feat's Last Record Album is a demon test of any vinyl replay. The heavy bass modulation can easily drown the vocals, but with the Excelsior fed by my Decca cartridge the vocals are clear and voices distinct even when sung in unison. The Excelsior demonstrates superb timing, despite the provision of negative feedback, on Day and Night the leading edges of cymbal strikes crisp and distinct and in time with the rest of the percussion. Day and Night's dynamic shifts are also portrayed in all their glory. The Excelsior excels at dynamic contrasts.

Soundstage is deep and wide, and has some illusion of height too, but I remember the top of the range Exquisite was even better in this respect. The Excelsior's soundstage is notable for its explicit portrayal of position. I do not mean that delusion of image precision that exists only in hifi reproduction, not in real life, but in the consistant way an instrument stays in place from the bottom of its range to its highest harmonics. Again, this contradicts what many commentators state about negative feedback. Doug's paradigm shifts still disturb the prevailing hegemonies.

There is some graininess overlaying the signal. I suspect this could be as much due to the age of the electrolytic capacitors as to any inherent flaw. Mark's sample is over 15 years old, which is way beyond the service life of even the best electrolytics. The background noise is still very low, but I would expect ripple to have suffered too.

[quaint_but_great]
Earlier Concordant Excelsior leaflet

Conclusion

The Concordant Excelsior does remain competitive after all these years. Mark Orr's example suffers slightly from graininess but still displays the greatness I remember. Perhaps modern thinking would replace the valve heaters' voltage-regulator with a current-regulator circuit. Modern thinking would however also demand fancy coupling capacitors too...and then where would you stop?

The variable output impedance never made it's presence felt during the review period, despite my 6metre pre-to-power amplifier screened connection. I would have expected a buffer stage to be necessary in this application but the Excelsior happily manages without. A typical Doug Dunlop paradigm shift.

The RIAA equalisation is inaccurate. The RIAA equalisation is applied using an active feedback circuit. The RIAA equalisation is a compound circuit. Modern thinking would imply that this would be expected to produce a lifeless phono presentation with a small soundstage, poor imaging, slow rhythm and inaccurate timing. But the Concordant Excelsior still has one of the liveliest lp presentations i have ever heard, a cavernous soundstage, and wonderfully coherent timing. Another paradigm shift from Doug several years after his death.

Music enjoyed during this review:

Copyright 2005 Mark Wheeler - www.tnt-audio.com

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