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conrad-johnson ET6SE preamplifier

conrad-johnson ET6SE preamplifier

There has been something of a rationalisation in the conrad-johnson line-up of late. While the brand has never been guilty of having a vast range of electronics, the current line-up of three preamps, three power amps, two phono stages, and an integrated amplifier must be one of the most streamlined the c-j brand has offered in years. However, far from paring back too far, this has a sense of right-sizing the brand for the current audio world. Yes there are gaps – no personal or digital audio products being the most notable – meaning this is a range without flab. And that’s good. 

That being said, depending on how you look at it, those three preamplifiers could be considered as many as six preamplifers. There are three basic models; ET6 occupying the ‘good’ slot, ET7-S2 in the ‘better’ position, and GAT-S2 as ‘best’. The specifications for the top two are fixed in place and there are no mix-ins or add-ons. Not so the ET6, which comes in standard and supercharger ‘SE’ guise, and there is an optional (and retrofittable) phono stage. And let’s get this out of the noggin right away; just because the ET6 is the most affordable of c-j’s current line-up of products, doesn’t make it the ‘entry-level’ or ‘starter’ preamp. This is through and through a c-j preamplifier, stripped to the bone in the ET6 and then built back up to fighting weight in the SE version, but this is not austerity audio and the ET6 is no pared-back preamp. If anything, it draws so much from past masters both above and below the price of the ET6 it’s like the distillation of all c-j preamps from the last few years, delivering – as they often do – far more of the performance of the mighty GAT-S2 than you might expect.

As ever, that ‘ET’ prefix to the name means ‘Enhanced Triode’, in that the circuit uses a single 6922 double triode tube, acting as a single-ended triode for each channel. This provides voltage gain, and sends the signal to a similarly minimal high-current MOSFET buffer, which helps provide a very low output impedance. This makes the single-ended only ET6 extremely flexible in terms of interconnect cable design and length. DC voltage is provided by a discrete voltage regulator that isolates the audio circuit from the power line by maintaining negligible impedance across the audio frequency band. In addition, infra-sonic noise is minimised by operating the tube heaters on a DC voltage supplied by a separate regulated power supply. Power up puts the ET6 into soft-start heat-up mode, and the blinking mute switch is a reminder of that.

The ET6 also retains the microprocessor-controlled relay system and network of metal-foil resistors as gain control, allowing one hundred 0.7dB steps in volume and balance, as seen in the ET7-S2 and GAT-S2. All that’s missing here is a balance control on the front panel; although it has two yellow volume displays, so you might expect to be able to adjust one at a time or even alter them individually. Visually too, the ET6 shares much with the ET7-S2, although the chassis is a centimetre or so thinner in this model. Both, however, retain a sort of Art Deco styling to the front. Even the number of inputs on offer are similar, with the ET6/SE having five single-ended line inputs and two external processor loop input/outputs, the second of which puts the preamp into ‘Theater’ mode and automatically switches the ET6 to unity gain. 

These are more than relatives, they are siblings; GAT-S2, ‘mini GAT’ (the ET7-S2), and now ‘baby GAT’ in the ET6/ET6SE. The ET6 isn’t the first preamp to receive that ‘baby GAT’ title, as it was bestowed on the ET3 preamp, which we tested a little under a decade ago. That classic preamplifier came with an optional phono stage, too, itself based on the circuit of the then-current version of the TEA-1 equaliser, the ET6 sporting a circuit based on the TEA-1-S3 that is today’s example. The phono stage itself offers enough gain and low enough noise to be good for moving coil cartridges of 1mV and below. The resistance loading of the phono module is adjustable thanks to two DIP switch arrays. Factory default is 47kOhms, but the ET6 board can cope with 9.6kOhm, 1.9kOhm, 200, and 500 Ohm loads. It uses a trio of 12AX7 double triodes.

 

The ET6 comes in two guises; standard and ‘SE’ version, but in typical c-j style, it doesn’t shout too hard about being a special version, even if it does have a lot to make it really special. Important signal path capacitors are replaced by CJD’s own Teflon devices, and metal film resistors of super high tolerances replace the standard resistors on the PCB. This is not a retrofittable option, and such is the cost of these components, the ET6SE closes the gap between the basic ET6 and the ET7-S2.

Price aside, there is only one real problem with having all those PTFE capacitors in a preamplifier; they take an age to bed in. There are c-j users who report hundreds, even thousands of hours before the preamp really comes into its own. OK, it gets most of the way there in a few dozen hours and the amplitude of the roller-coaster effect of sounding good, sounding bad is reduced. But it’s worth bearing in mind that if you play it for a couple of hours a night and power down after use, you could be a year or more from hearing just how good it can get. I think I’m working at about 8/10 in sonic terms.

Even this early in, it asks big questions of the listener. And one of those questions is ‘just how much more do you need’? That ‘baby GAT’ title is more apt than ever, and while the E`T6/ET6SE is perhaps more evolution of the ET3 rather than revolution, the GAT-like presentation is so beguiling and downright enjoyable in so effortless and naturally musical an approach that it makes you wonder if spending that bit more on the ET7-S2 or even the GAT-S2 is worth it in absolute terms. Of course, if you have logged any time with the bigger models you begin to understand the importance of a floating suspension system in the GAT-S2 and a more intricate power supply makes a big difference, but the ET6SE closes the gap.

In preamps starting about the time of the ART, c-j began to change its tone, from a rich and always pleasing if slightly majestic tone, to a more modern and inherently neutral sound. It still represents a more easy to listen to presentation than the forward and bright amps that spring up almost everywhere, but now the sound is one of precise and seemingly limitless soundstaging, ‘in the room’ solidity, and coherence that makes this and other c-j’s so authentic sounding.

I played the ET6SE into a Chord Étude power amplifier (inverting phase at the speaker terminals) into a pair of Wilson Duette S2s, with a VPI Prime and the EAT Jo No 5 cartridge as a vinyl front end, and the awesome Lumin X1 as a digital source. And I played a ripped version of Jimmy Scott’s ‘Nothing Compares 2U’ on his Holding Back The YearsCD [Artists Only!]. The little old guy with the high-pitched voice nailed that track and the emotion in his voice could stir the coldest of hearts, but with the ET6SE in the mix, it’s impossible not to be torn apart by the track. I don’t play this too often because its so special, but there’s a sort of gentleness and pathos to his voice undercut by an excellent arrangement and some very sensitive recording. I knew all that, but I didn’t expect quite the outpouring of emotion the ET6SE parses. It’s one of those ‘I can’t turn this off because it would be a crime against music’ moments. After hearing that and getting that pervasive grit that seemed to have lodged itself in my eyes causing them to water, the rest of the review is little more than a series of tick boxes. All of which the ET6SE passes with flying colours. Of course it is detailed and dynamic – put Kleiber’s Beethoven Fifth Symphony [DG] on and enjoy the ride, or put the Solti Mahler Eighth [Decca] and be prepared to be pinned to a wall. But you also have that wonderful articulate sense of musical flow, both in terms of interplay of instruments as well as that of harmony. The structure of a piece of music is extremely easy to spot here, as each musical theme is teased out; not forensically examined, but savoured and enjoyed.

This applied universally. The phono stage is a bit of a honey for an on-board design. Not only does it have provision for a wide range of cartridges, it’s extremely quiet in use, and deeply musically satisfying. It’s a lot more than simply an afterthought, and a separate phono preamplifier this good costs thousands in its own right.

Overall, the performance is best summed up as ‘intelligent’. It’s not the immediate and forward sound of high-priced, low-brow audio, or the too soft rose-tinted view of the past. It is – like so many conrad-johnson preamps before it – poised and balanced in sound, and that makes it so endlessly satisfying and music played on the ET6SE infinitely fascinating.

 

That ‘baby GAT’ title could be a millstone around the neck of the ET6SE, but instead conrad-johnson’s latest lives up to the hype. It might take months to run in, but it will be worth the effort, as it manages to combine old-world charm with new-generation excitement all in a package that at once retains classic conrad-johnson characteristics and channels the best of the past and present in c-j’s preamp line-up. If it’s not the perfect form of a c-j preamp, it’s possibly only because of the presence of the awesome GAT-S2. That being said, you can buy almost three ET6SE’s for the price of one GAT-S2. As it takes so much from the GAT-S2 without that much real sacrifice in sound quality terms, the new ‘baby GAT’ is going to be a tough little blighter to beat.

TECHNICAL SPECIFICATIONS

 Type: single-ended valve preamplifier

Inputs: 5×single-ended RCA stereo line-level inputs, 2× single-ended RCA processor loop inputs

Outputs: 2×single-ended RCA stereo variable outputs, 2×single-ended RCA processor loop outputs 

Tube complement: 1 ×6922

Gain: 25 db

Maximum output: 20 vrms

Output impedance: 100 ohms

Distortion: less than .15% THD at 1.0 V

Frequency response: 2 Hz to more than 100Khz

Hum and noise: 98db below 2.5 v

phase: inverts phase of all inputs at main out

Optional phono stage

Gain: 54dB

RIAA Equalisation: ± .25dB 20hz–20kHz

Hum and nNoise: -80dB relative to 10mV input

Phase: phase correct

Tube Compliment: 3×12AX7

Dimensions (W×D×H): 48.3 ×41 ×9.5cm 

Weight: 6.8kg

Price: £6,495 (line stage only); £1,945 (optional phono stage)

Manufactured by: 
conrad-johnson design, inc.

URL: conradjohnson.com

Distributed in the UK by: Audiofreaks

URL: audiofreaks.co.uk

Tel: +44(0)208 948 4153

Tags: FEATURED

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