Coincident Turbo 845 SE Integrated Amplifier
Transcending the recording... Ignoring the equipment... Enjoy the music!
by Rick Becker | September 2013
The Turbo 845 SE has the makings of a classic amplifier that can be the cornerstone of a musically rewarding system when combined with equally accomplished front end components and speakers. It is an end game product for those with limited space, limited budget or an inclination to concentrate more on the music than the machinery. For anyone truly seeking to enjoy their music and take the focus off the equipment, this is the path. Integrated amps are not normally optimal for reviewers because of their need to swap and compare products but this one has some additional flexibility. As a reviewer, the Turbo will probably be one of the components I most regret having returned to the manufacturer when my time is up. Our children will probably hate me for letting it go, just as I regret my parents not buying an AC Cobra back in the mid-60's when they sold for $6000 — same price the Turbo is now. But let me get down to work.
Is it perfect? Not for every situation. The relatively low 28 wpc power rating suggests that you will have to pair it with a moderately efficient loudspeaker in spite of the fact that those are Class A "tube watts". But with the massive power supply storing 510 joules it is capable of putting out 100 wpc on musical peaks opening the window of opportunity to pair this 100 pound beast with some unlikely candidates. With its low output impedance and enormous power supply it is claimed to be able to handle speakers with impedance as low as 3 Ohms, which opens the window even further. There are also many high efficiency speakers that would virtually eliminate amplifier clipping for all but a few micro-seconds of most music. It helps, too, if the loudspeaker has a relatively benign impedance curve. Avantgarde, Zu Audio, Tekton Design and of course Coincident's own speakers which are efficient and designed to be driven by tube amps, come to mind most readily. A carefully researched list would certainly be much longer — especially if you consider loudspeakers with active woofers. Depending on the size of your listening room and the type of music you prefer, this list could become quite long.
Let's begin with the form factor because that's what stands out the minute you take delivery. It's heavy metal. This is a classic tube amplifier with roots that stretch back to the invention of recorded music. Large tubes on the front porch, heavy transformers concealed under a polished stainless steel box out back. It's the antithesis of Class D laid out in a thin chassis with a footprint the size of an Apple iBox. It will sound a lot different than Class D, too. The chassis itself measures 290mm wide (11.5") by 530mm (20.87") but the 10mm thick anodized aluminum faceplate is 310mm wide (12.25"). Overall depth is 580mm (22.87") and you will need another eight inches or so to bend a serious power cord into its IEC socket as well as room for the interconnects. Height is 250mm (9.87") to the top of the Psvane 845 tubes, but the tube set puts out a fair amount of heat that demands sufficient air space for cooling to prolong the life of the tubes. I configured an amp stand with a couple of slabs of 2.5" thick architectural slate capped with a wood top from an old chest of drawers. To lift this amp, you'd think the bottom two inches were filled with concrete, but a lot of the weight is due to the high quality Japanese steel used in the transformers. (The weight came as no surprise to me as the separate power supplies of my Coincident Statement Line Stage and Phono Stage are each the size and weight of power amps. Coincident believes in huge power supplies.) Keeping the Turbo low to the ground is a plus because the 845 tubes throw out a white light that is multiplied by the polished stainless steel. Listening in the dark is only a metaphor with the Turbo. I placed it behind the right speaker close to the equipment rack with the back of the amp facing the wall. Being offset like that allowed for two-meter interconnects and put the tubes in my peripheral vision, but it is such a beautiful amp I could easily understand if you wanted to prominently display it between the speakers.
The power switch is on the top front left corner and requires considerable force that led to anxiety when I used my right index finger to turn the amp on or off. The fear was that my finger would slide off the smooth toggle switch and bump into the small 6EM7 tube, either breaking it or burning my finger. I conquered my fear by using my left thumb on the toggle switch with my fingers curled around the left side of the slightly protruding faceplate. Problem solved. The power switch is the highest quality military grade with maximum voltage capacity in order to handle the high voltages when turning on the amp. Don't plan on it ever becoming easier to flip. I'm also told there is no chance it will ever arc. The phrase "built like a tank" immediately comes to mind.
Connectivity & Control
Aside from the standard headphone jack on the faceplate, all cable connections are made at the rear. Three line level inputs are all single ended RCA connectors of high quality. The Euro-style speaker binding posts that came on the review sample will normally be the standard Coincident 6N copper binding posts used on all their amplifiers and speakers. My experience with other Coincident review samples and my own Partial Eclipse II speakers over the years is that they hold very well and are easy to secure tightly. They are said to be sonically superior to the Euro posts and they look to be a good bit more expensive. Both types allow for sandwiching a pair of spade connectors if you must bi-wire, but the proximity of the power cord and interconnects makes this a challenging task. Using one speaker cable with banana ends and the other with spades would simplify matters. Or, use those fancy banana plugs that let you piggyback a second banana plug into it. (I encountered the need to bi-wire when using the Zu Union speakers with the Tekton Design subwoofers in my previous review.) The other minor annoyance was the labeling of the inputs. Black letters silkscreened onto polished stainless steel are hard to read. A second set of labels, upside down, above the inputs would make it easier to identify specific inputs when bending over the amp from above. Color coding the labels to match the colored LEDs on the faceplate would be cool, too.
If an inventory of the tubes on top suggests the preamp stage is passive, you'd be right. NOS RCA 6EM7 tubes are used as the input tube and Psvane 300B tubes are the drivers for the Psvane 845 power tubes rated at 28 watts per channel. These are the clear glass affordable Psvane tubes from their HiFi series. Their high end black bottle tubes would be an upgrade path if you feel the need, though I'm told there is little sonic advantage to using a black bottle 300B in this amp since it is the driver tube. Psvane, manufactured in southern China, is fast becoming a premiere tube manufacturer on the global market. For the inside scoop on this relatively new company see their story here. Coincident buys their Psvane tubes in bulk and both matches the tubes and tests them for low noise and distortion, using only the ones that meet their rigorous standards. Would it be an oxymoron to say these tubes look like they are built like a tank?
A velvet-smooth volume control is front and center on the top plate but most likely you will enjoy the small remote control machined from billet aluminum that controls the volume, source selection and mute. While the top mounted volume control is infinitely adjustable, the volume control from the remote jumps in small steps. Nonetheless, there was much finer control with the remote than what is available from the twin volume controls on my Coincident Statement Line Stage, so I immediately became addicted to using it. I noticed no sonic penalty in using the remote vs. chassis mounted volume control. So nice was the remote that I asked Israel Blume if there were plans to introduce the remote on the Statement Line Stage. He replied:
"Cannot be done since it is completely different circuitry. The Statement Line Stage is all transformer coupled including the volume controls. A remote requires a motor to move the control. To move the Statement's would necessitate a large motor which would not fit into the chassis. We are about to introduce the new Statement Line Stage RC (remote control) which will incorporate the same remote control system as the Turbo. There will be a bit of sonic penalty since the transformer coupled volume control (the purest available) will be replaced with a variable resistor pot like the Turbo. Still superior to any Line Stage in existence but not quite as pure as the current Statement."
Recessed into the faceplate on the right are small LEDs that indicate CD (red), Aux 1 (yellow) and Aux 2 (green) for the selected source. The colors were easy to differentiate from the listening chair ten feet away. The fourth LED at the top of the column is also red and comes on automatically when you turn on the amplifier. It stays lit until the motor automatically resets the volume control to off. Presumably this is a safety feature to keep the music from blasting before the tubes have warmed up at the beginning of a listening session. Once an appropriate level has been established via the knob on the chassis or the remote, this doesn't happen — the volume remains as-is when you change CDs or LPs. Since there is no LCD screen or notation on the volume knob to indicate the playback level before hand, it is necessary to fade-in the first piece of music from silence thus missing the opening bars of music. As a work-around I taped a black line on the top of the volume knob so I could pre-set the volume before listening to the first track of a listening session. A drop of black nail polish would be a more permanent fix. Or for maximum effect it could be taken to your local nail parlor. In addition to the mute button on the remote, a push-button on the faceplate beside the red LED for mute also activates the mute. Likewise, there is a small button on the faceplate to cycle through the three inputs in the event your recliner has swallowed your remote. Individual buttons on the remote allow for random access to the inputs.
Current Production Models
My review sample was from the first production run and models produced from August 2013 onward will have two additional features. First, there will be a direct input to the amplifier section that by-passes the source inputs and potentiometer for those who wish to use the Turbo solely as a power amp. I was able to virtually duplicate this by running my Statement Line Stage into the Turbo with the potentiometer on the Turbo set wide open and using the transformer coupled volume control on the Line Stage to control the volume. I used the same Kharma interconnects and the same input on the Turbo in both trials, but since the volumes were adjusted by ear, any slight difference I thought I heard is highly suspect. This configuration also allowed me to set the Line Stage wide open and use the remote control of the Turbo to adjust the volume, preserving that convenience and the mute function as well. Both volume controls seemed to be of the highest quality with little if any difference between them revealed in this casual comparison. Another possibility was also offered by this arrangement. I substituted a 1meter Audio Sensibility Statement balanced interconnect from the DAC to the Statement Line Stage in place of the Kharma single ended interconnect. After several rounds of comparison I was just barely convinced there was a slight improvement in dynamic contrast using the balanced cable, but again, since the volume was adjusted by ear, this conclusion is suspect. With longer cable runs there might prove to be discernible justification for using balanced interconnects, but I didn't find any penalty with a short run.
The second change in current production is the addition of a standard 300 Ohm headphone jack on the right side of the faceplate. The power stage is simply padded down from 28 to 20 watts — way more than enough for typical headphones which draw about a watt, and still more than enough for electrostatic headphones which draw 5 to 10 watts. Depending on your head to toe distance, the Turbo will act as a superb foot warmer in the winter when listening to headphones. While it may be a bit of overkill as a headphone amplifier, it is a nice feature for those who on occasion want to listen loud when others want to sleep.
I first encountered the polished stainless steel chassis that has become the hallmark of Coincident amps when the Frankenstein Mk II Monoblocks made a brief visit in late 2008. I reviewed them in concert with the Coincident Total Victory V speaker before they both headed west to the CES show in January, 2009. In the spring of 2010 I reviewed the Statement Line Stage and bought the review sample, subsequently awarding it a Blue Note Best of 2010 Award. A year later I added the Statement Phono Stage to my reference rig, so you can deduce I must like the look. I've become so accustomed to it that it's hard for me to get excited about it at this point. That's good news, because it tells me it is withstanding the test of time. It's still sexy, but in a mature way — not like the hot new babe in my life that it once was.
It really is dressed up when paired with the piano gloss black Kharma speakers yet can be dressed down like a shiny western belt buckle on a comfortable pair of jeans when paired with the satin walnut finish of the Zu Union speakers. It counterbalances the chrome on the vintage motorcycle in the garage and it complements the green jungle plants along the front wall of the listening room. For listening in the dark it reflects enough light for me to safely cross the room to flip an LP. As a large amplifier placed upon the floor it vies with the speakers for the attention of our guests. And at the claimed 100 pounds, you will vacuum the floor around it, but not likely under it. Although it occurred to me that I could use a furniture dolly as an amp stand to facilitate those occasions when it had to be moved. Note that unless you are very strong or very skilled at moving heavy objects, have a suitable friend help you unpack and position the Turbo. An injury will severely diminish the joy of acquiring this wonderful amplifier.
Old School/New School
As I read over my previous reviews of Coincident speakers and amps I realized my writing style was a lot more exuberant than what I'm putting down here. Been there — done that — and Enjoy the Music.com has also featured an in-depth article on Israel Blume and Coincident. It should be clear by now that Coincident Speaker Technology is one of the premiere manufacturers of high end audio gear in the world. That they haven't become as large a company as some of the other brands speaks to their commitment to maintain control of their high standard of quality rather than trying to be all things to all audiophiles. The company is right-sized and the products are priced right. Their multiple speaker designs are aimed at filling different room applications, not necessarily multiple budgets. Nothing in their line changes just for the sake of having a "new" model. Their amps are designed to be the best of their type without superfluously enlarging their price tags. We're talking auto-biasing circuits, zero global feedback, no circuit boards — everything is hard wired. Actual wire is used when the leads of the parts cannot be directly soldered together. Signal paths are kept as short as possible and critical attention is paid to isolate the sensitive input circuitry from the high voltages of the power supply which would induce hum and noise. The signal-to-noise ratio of the Turbo is claimed to be 90 dB, which is very good for a tube amplifier, and channel separation was excellent due to the true dual-mono configuration, save for the chassis and the incoming power cord and switch.
Don't others use these same techniques, you ask? Well, some do, but some do it better than others. Obviously, one of the top priorities is to be emotionally involved in the music. Of course it takes a good (if not great) recording, a well-coordinated rig and a thoughtfully laid out room to achieve that experience. Others may have other priorities such as those that lead many audiophiles into the world of solid state gear. When I'm hiking up mountains I have different food priorities than when my wife and I go out to dinner. Imagine Clif Bars versus seafood. And the mellow low-fi background music I enjoy at work would be totally unacceptable in my listening room at home. But when it comes to maximum enjoyment of music I turn to tube gear for the intimate and detailed replication of "being there". In the world of tube gear, Israel Blume is one of the master chefs.
A few years ago after attending the Toronto furniture show I visited Coincident and had the opportunity to listen to some of my own familiar music, both analog and digital, on their reference system. Everything except the source components was of their own manufacture, including the wiring. For the record, no power treatment was employed, much to my disbelief. It was one of a handful of finest systems I've experienced and I fondly adopted it as my own "reference in absentia". Unfortunately, I've been "in absentia" ever since. The sound was not unlike my own, except at a much higher level. More recent upgrades to my digital and analog front ends have brought me much closer, but there is no way the single 9" woofer of my Kharma were going to match the four 12" woofers on each channel of his double-Pure Reference Extreme speakers. The Accuton ceramic midrange drivers are common to both speakers which significantly contribute to the similarity. The point here is that my audio values and those of Coincident are virtually identical so you need to be aware of how yours differ from theirs and tone down my hot sauce with your favorite micro-brew.
The Word From Henry's Swing Club
Stepping back a review or two, I was really digging the new Zu Union speaker being driven by the Triode Lab EL34TT Mk II integrated amp. For a speaker with 99dB/W/m sensitivity, the 6 wpc TT was a muscle amp with tight bass and extended treble. The combination was exceedingly transparent and dynamic, but word was that the Triode Lab 2A3 Classic stereo power amp with 3.5 wpc was even better. I teamed their 2A3 with the Coincident Statement Line Stage and discovered one of the most emotionally engaging presentations I've ever heard. Musical enjoyment to the max, yes. Musical truth? — only with fingers crossed behind my back. Take another swig of your favorite micro-brew.
I then teamed the Turbo with the Zu Union, first alone and then with the Tekton Design subwoofers. This was a serious, reasonably priced reference combination. Tight authoritative bass down to the lowest organ notes on Master Tallis's Testament from "Pipes Rhode Island" — powered by the internal BASH amplifier of the subs, but with the signal coming through the speaker terminals of the Turbo. The somewhat questionable super tweeter of the Zu was very nicely tamed and the midrange through the crossover-less full range driver was ultra-transparent and very well focused. Dynamics were you are there! I felt like I had just come off a mountain and was confronted with the choice of twenty flavors of ice cream at Custard's Last Stand in Blue Mountain Lake. Never before had I hosted so many delightful products for review at the same time. And more to come, I might add.
Ultimately I had to get back to my reference configuration and drive my Kharma with the Turbo — the moment of truth, so to speak. The Kharma are 89dB/W/m efficient and have a complex crossover embedded in vibration quelling material in the bottom of the speaker. Focus is further enhanced by Boston Audio Design TunePlates under the spikes and 4x4 wood posts between the joisted floor of the listening room and concrete floor of the basement. I consider the Kharma moderately efficient and experience has shown they are a fairly easy load for tube amplifiers. A really good 8 wpc 300B amplifier might be used in a small to medium size room, but my reference for years has been the 18 wpc Tube Magic monoblocks with parallel 300B tubes, now in Mk 3 guise. The Kharma are noted for their top to bottom coherence and for the music's ability to get completely out of the box, making these relatively large speakers virtually disappear. The replacement model has jumped up to $39,000 and comes with new proprietary drivers of Kharma's own design. I haven't heard it yet, so I can't comment on it other than to say I expect it would be quite good.
"Stepping down" from monoblocks to an integrated amplifier with a passive line stage I was expecting less but the Turbo actually stepped up to the plate with confidence. Compared to the Tube Magic monoblocks the music was less lean and the soundstage was less pinpoint in its imaging. It was more like live music in real space. The musicians were realistically placed on the stage but not isolated from each other as if they were on separate islands in the Caribbean. The space was continuous and believable. The continuity from low bass to treble was seamless and exceptionally flat. In particular, the mid and low bass were well controlled, exhibiting sufficient silence to reveal the room tone in live recordings. The additional payoff was very good focus and transparency in the upper bass and lower midrange. The Kharma did not growl with authority in the lowest octave like the Tekton subs with the 300 watt BASH amplifiers, but they certainly handled bass well down to their 32 Hz limit, more than enough for most music I normally listen to. As I mentioned above, there seemed to be no sonic penalty to the passive line stage, contrary to conventional wisdom. This is testimony to Israel's design skills. If you do choose to add an active line stage for greater connectivity or because you need to drive longer interconnects, there should be no penalty if you select a good one.
Since I was using the Synergistic Research Tesla power cord with the active shield I tried the different tuning bullets to see what effect they might have on the signature of the Turbo. Listening late at night I thought I could easily discern a difference between the silver and black Enigma bullets, but the next day, well rested, the differences were much less obvious. All three bullets sounded very fine. I also tried a JPS Labs SuperConductor+ power cord which sounded a bit more dynamic, and a Coincident CST power cord that seemed a bit more neutral, but with less tonal color. Overall, I preferred the Synergistic Research cable for its more holographic imaging that ultimately evoked a more emotional connection with the music for me. The choice of power cord is one of fine tuning as they are all very good cables, commensurate with the price and performance of the Turbo.
Recollecting that the Coincident reference rig in Toronto used no power conditioning, I also ran the power cord directly into the 30 amp dedicated line from JPS Labs, by-passing the Synergistic Research PowerCell 4. There wasn't much difference which indicates there is significant isolation built in to the Turbo and possibly this is why the Enigma tuning bullets were so similar. What was most noticeable was refinement in the sound of cymbals and cleaner air in the treble — not a huge difference, but enough to make me re-connect the amp to the PowerCell 4.
I kept going back to the rig listening for something I might be missing, but the music just kept coming out clean and dynamic with all the pace rhythm and timing needed to keep my left foot bouncing on my right knee. It is exceptionally neutral leaning very slightly to the warm side, which is preferred by most. For an integrated amplifier it is very transparent with very high resolution — but never analytical. Only in comparison with the Tube Magic monoblocks does the Turbo lack the last bit of harmonic resolution and air that comes with the very finest separate components — ultimate refinements that come with a much higher price tag and require a lot more floor space. Nonetheless, the Turbo 845 SE makes it easy to transcend recorded music and reach that level where you ignore the equipment altogether and commune with the music. In this rarified air the differences become increasingly smaller. Greater joy will most likely come at a much higher cost. As prices continue to escalate into the esoteric sphere of the 1%, Coincident is to be commended for offering first class components with outstanding build quality at relatively affordable prices. The Turbo 845 SE is another prime example. When paired with an appropriate speaker it is very highly recommended. On top of that, it is a beautiful amp that one of our children will be proud to own (someday) as I've decided to buy the review sample.
Type: Stereo integrated vacuum tube amplifier
Tube Compliment: Two each 6EM7 input tube, 300B driver and 845 output
Inputs: Three analog stereo sets via gold-plated RCA
Power Output: 28 watts per channel
Frequency Response: 20 Hz to 20 kHz (+/-0dB)
Sensitivity: 1V for full output
Input Impedance: 100 kOhms
S/N Ratio: -90 dB
Design: Pure dual mono, all hard wired with 6N copper
Japanese Steel proprietary power and output transformers
Discrete Resistor volume control
Voltage selectable 115V/230V
AC ground lift
Weight; 100 lbs.
RCA 6EM7 (NOS) $30
Psvane 300B HiFi Series $150
Psvane 845 HiFi Series $135
Coincident Speaker Technology
19 Strauss Road
Ontario, Canada L4J 8Z6
Voice: (905) 660-0800
Fax: (905) 660-1114