Friday, April 26, 2013

Review: B&W Matrix 805 loudspeakers

Bowers and Wilkins have long been audiophile darlings.  I'm no historical expert, but from my many years of reading the audio specialty magazines, it is the venerable 801 studio monitor that cemented their reputation.  Unlike many other speaker makers, they also produce their own drivers, and have an engineering staff on board to build excellent crossovers and cabinets.  This attention to quality is hardly extraordinary in the world of audiophiles, but like their British competitor KEF, it speaks of a long term love of the black arts of speaker design.

My own personal experience with B&W is very, very short.  The only pair I've personally heard was back in the 80s, when my best friend had a pair of stand mounted units of an unknown model.  I don't specifically remember much about the sound other than the speakers could take all the power that the Denon receiver could dish out.  This was, of course, before my audiophile days, when playing clean and loud was all that mattered to my teenage ears.

Time for a New Speaker?
Moving to a new house with a smaller listening space, and a Denon DL-103R cartridge that got damaged during the move, tempered my audiophile equipment craving.  Instead I pulled back on my expenditures, scaling back the size and quality of my system by going with a pair of KEF iQ30 speakers that I already owned, and buying a new Denon DL-110 cartridge.  I even stuck in some Chinese EL34 tubes for my Eico HF60 monoblocks, wanting to save my vintage Mullards for the day when I had a larger listening room.

However, fate being what it is, those plans of hanging back were thwarted by the purchase of a VPI Aries 1.  This was not a turntable purchase that I was planning to make, but it was such a hard deal to pass up - being local and priced lower than what I was seeing on Audiogon - that I took the plunge.  The resulting sound, even through the budget KEF monitors, was a major eye-opener.  I'll be reviewing this turntable in a separate post, but needless to say the overall sound, even with a budget priced Denon DL-110, became much more dynamic, involving, and was quite the step up in reproduction.  After hearing the Aries, I knew that to get the full effect I had to upgrade the rest of my stereo system.  I also knew that with my smaller listening space that approaching the bass and dynamics of the UREI would be near impossible, but perhaps I could be sated with a mini-monitor of high enough quality.

My initial thought was to go with KEF - specifically the KEF LS50, but the low efficiency of 85dB made me wonder if 60Ws of tube power would be enough.  The lower-end models of KEF had their own issues.  For example I wondered if the current Q300 model would really be a major upgrade versus the iQ30s currently in the system.  Browsing through Audiogon for monitors under one thousand dollars, I came across the B&W Matrix 805s, the baby brother of the famed 801s.  My interest piqued, I read the Stereophile review and this post by Ken Rockwell.  Both are excellent starting points if you wish to have a deeper technical description of these speakers.  Needless to say, I was thoroughly interest in this speaker now.  Though the efficiency is only a rated 87dB, it still seemed worth taking the risk.  I purchased the 805s and soon had them in my hands.

Initial Impressions
Opening the box and unwrapping the yards of bubble wrap, I was greeted with a very nicely built pair of mini-monitors.  The enclosure made of rosewood (veneer?) is very lovely.  Binding posts on the rear are recessed and gold.  The woofer is a 6.5" kevlar unit while the removable bullet tweeter on top is a metal dome that is time-aligned by a fourth-order crossover.  An extra feature is the optional outboard electronic crossover/filer the cuts bass off below 10Hz but firms up the response between 10Hz and 50Hz.  This could be useful to reduce turntable subsonics and improve the low-end for rock or symphony music.

Installation was on top of my UTI 29" tall stands, bi-wired with budget Kimber 8PR/4PR.  Distance between the speakers was some 7' from each other and perhaps 2' from the sidewalls and 3' from the rear wall.  Obviously not a cavernous listening area, eh?

Using the Denon DL-110 cartridge, along with Hitachi 5AR4s and Shuguang EL34s installed in the Eico HF60s.  The first record up on the Aries 1 turntable was Neil Young's "Live at Massey Hall".  This recording is fantastic - however with only one singer and guitar (or piano) it is by no means a complex or very dynamic album.  Nonetheless, it is a good album for picking out overall sound quality.  The treble sounded very clean and polite.  The midrange was clear with plenty of detail and space.  The bass, which isn't very deep on this album, had a slightly wooden character.

The next two albums: a German pressing of Pink Floyd's "Animals" and a Japanese pressing of Steely Dan's "Greatest Hits" showed the natural limitations of all small speakers.  As expected, ultimate dynamic range and the lower bass of the B&W 805s were limited by the small woofer size.  Yes, I'm being quite unfair comparing such a minute speaker to the massive UREI 813As, but I'm just reporting what I heard.  When the bass got really deep, the 805s didn't choke, but instead began to slowly compress, leading to the already mentioned wooden character to the bass.  However, throughout the dynamic swings, the sound still remained balanced and focused without getting gritty or uncontrolled like the KEF iQ30s.

Getting Deeper:
Now it was time to upgrade the rest of my system.  First it was a new cartridge: the Dynavector 10X5.  This is a good, dynamic high output moving-coil cartridge that works quite well with the Aries 1 turntable.  After that, it was time to bring out the best tubes I had for my Eico HF-60s.  Out went the Hitachi and Shuguangs, and in went my vintage Mullard tubes.  I also replaced the GEC CV4085s (EF86) with the very earliest and rare "long plate" versions that Mullard made.

These changes were proof positive that rolling in the right tubes can have a major impact on the sound.  Not only did the midrange become more relaxed, but the higher frequencies were even smoother than before.  The Dynavector 10X5 has always been a dynamic cartridge and partnered well with the B&W 805s.  Sure, the UREI 813As still hold sway in the explosive bass department, but for such a small speaker, the overall frequency response was much improved.

You Got to Equalize! 
B&W also included a small bass equalizer with the 805s.  Since I didn't have another pair of Cardas interconnects on hand, I opted to use some budget Canare wire to make the connection between the Quicksilver preamplifier and bass equalizer.  From the output of this little unit, Cardas Cross wire was used.

The change was immediately apparent - this small speaker now growled like a much larger speaker.  Again, it was nothing like a big speaker with multiple drivers, but it sure helped with rock 'n' roll music.  The wooden character of the bass was gone and instead became really firm and punchy.  However there was a bit of detail loss, but for the types of music I listen to, I definitely preferred the improved bass response.  Now I will have to go ahead and buy a short run of Cardas interconnects.  However purists or listeners of lighter fare may prefer the speakers without the additional wiring and active equalization.  Try it both ways.

Speaker Cable Upgrade:
The Kimber 8PR/4PR is great budget wire, but I was curious to hear how my vintage Cardas Hexlink speaker cable would fare.  So back in went the binding post jumpers on the 805s, and on went the Cardas.  The change was quite immediate - the slightly bright, polite sound became much more relaxed.  The top-end treble also smoothed out, turning the monitor into one warm, full-bodied speaker.  Wow.   I would never expect such a major character change from a few feet of cable.

Details R Us
Bass Response:  Hey, this is a small speaker with a relatively tiny woofer.  Expecting subterranean bass suitable for hard rock or organ music is just plain wishful thinking.  If you like that kind of music, you either need a larger speaker or an additional subwoofer.  However, with the B&W bass equalizer installed, lower frequencies are served well enough that I don't miss my big studio monitors (too much).  The sound became really punchy with good detail.  It wasn't all boom either, but instead the bass became very tight and controlled.  Obviously some thinking went into the speaker crossover design and the additional needs of the equalizer.  Again, very dependent on system and musical tastes.

Midrange: Compared to the UREI 813As, which are ruthlessly neutral as befitting a real studio monitor, the 805s have a slightly recessed sound when using the Kimber wire.  This was tremendously reduced by the Cardas cable.  When the music gets really busy or the dynamics really start swinging, it's almost as if the speaker is slightly "holding back" as the big peaks swell up.  Once again, perhaps this is just the effect of a small speaker being asked to do the work of a larger one.

Detail was exemplary - fingers on strings, studio effects, and overdubs were just that more obvious than many other (more budget) speakers I've heard.  The level of available information was much higher than my old Magnepan 1.6QRs, but not quite in the Quad ESL-63 league.

Treble:  The 805 tweeter ranks up there with some of the better I've heard.  It's clean but not totally antiseptic.  It's also very detailed  Sure, it doesn't quite strike in the electrostatic speaker or the plasma tweeter level, but it's no slouch either.  Admittedly there is a slight bump in the highest of frequencies, so some system matching is paramount here.  For example, the wrong solid-state amplification or an aggressive moving-coil or DAC could play havoc with the system balance.  Be also sure to play with speaker wire, as my Kimber vs. Cardas experiment proved.

Other: Even at loud listening levels, the 805s never fall apart.  That is to say the speakers never sound ragged or uncontrolled.  Soundstaging placement, width and depth are also very good, letting instruments and voices sit naturally within the space of the recording.  There was some minor shrinkage - as to be expected - of image size compared to larger speakers.

Speakers in the less than one-thousand dollar range are a hard nut to crack.  My advice in this range is to buy the best used model you can afford.  The B&W Matrix 805 is one such model.  I'm sure there are many others, but few in this price range can match the engineering, quality, and performance of these top level speakers.  I expect the 805s to have a long shelf-life in my current system.  Highly recommended.

Review System:
VPI Aries with JMW 10.5i tonearm and SDS Power Supply
Dynavector 10X5
Cardas Quadlink 5C 1M interconnects
Quicksilver preamplifier with Mullard short-plate 12AX7s, RCA 12FQ7s, Raytheon black-plate 5814
Cardas Cross 1M interconnects
EICO HF-60 monoblocks with Mullard XF2 EL34s, EF86s, 5AR4s, and GE 6SN7GTAs.
Kimber 8PR/4PR 2M bi-wire cable or Cardas Hexlink
VTI UF29 stands
VTI BL503 equipment rack

Thursday, April 11, 2013

Building a single-ended 6CB5A amplifier

After the success and sale of my single-ended 1625 amplifier, for my next amplifier build I decided to return to the venerable triode.  However, I wanted a bit more power than your average single-ended 2A3 amplifier, but still didn't want to use the pricey 300B.  With that in mind, I looked at several push-pull designs using the 6B4G or 2A3.  Once again I ran into expensive tubes, even for Russian or Chinese versions, and pricey interstage iron.  However, after reading several threads on, I came across Thomas Mayer's blog describing the use of the 6CB5A - a TV vertical deflector tube - in single-ended mode to make 7Ws.  He touted it as a budget alternative to the 300B, and at ~$5 to $6 a pop on Ebay, it certainly would cut down on the output tube cost.

Once I had the signal schematic in hand, I went and designed my own power supply circuit around a Edcor power transformer.  Note that the 6CB5A uses a mighty 2.5As of current at 6.3V.  This required an additional filament transformer for the 6N7 driver tubes, and, in order to reduce costs, I stuck with a 5V rectifier tube since the filament tap was available instead of the recommended TV damper diode which would require an additional transformer..

Once again, this is a budget build, so Mouser and Allied Electronics were used heavily.  This means electrolytics used in series to get a high enough voltage rating, Cornell-Dublier metallized polypropolene coupling capacitors, plastic speaker binding posts, and plenty of KOA resistors.  Output transformers are 3.5K/6-ohm units from Edcor.  The power transformer was also sourced from them.  For the top plate I used Front Panel Express.  Wood chassis is from Valab, an Asian Ebay seller.

This was an exercise in point-to-point wiring, which can be frustrating if one is not experienced.  A single star ground is used near the RCA input jacks.  Wiring is all plated solid-core.  Due to the simplified power supply and lack of regulation, this unit was much easier to finish than the 1625 amplifier, my last project.

After a quick voltage and current check, I hooked this amplifier up to a pair of Pioneer BS-21 speaker that I use for test purposes.  At 84dB efficiency, these aren't exactly a great match for single-ended amplifiers, but at least I can tell if music is being made.  The sound, via my VPI table and Quicksilver preamplifier, was very smooth without any noticeable hum or other noise.  With my medium-output moving coil cartridge, I had to turn the volume control way up to get any decent playback level.  Of course such a low gain amplifier will prove to be useful for much more efficient speakers than the test Pioneers units.

After everything checked out, it was time to listen to the 6CB5A amplifier with the KEF iQ30s.  Once again my big UREI 813As, which would be a much better match, are in storage so I had to make due with what is on hand.

This amplifier is smooth, coherent and almost touches the better 300B amplifiers I have built.  The soundstaging in uncluttered with a deep and immersive soundfield - all traits of a triode amplifier.  The bass was also surprisingly well-controlled, lacking that fat underdamped sound that plagues some tube amplifiers.  Treble extension was smooth with a nice shimmer and swirl to high hats.  Detail was also very good, providing plenty of definition - eg, recordings sounded different and weren't congealed into a "it all sounds the same" blob.

Switching to the less efficient B&W 805s and I noticed the amplifier would run out of steam on big peaks.  Obviously not a good match, but at lower listening levels it was quite the pleasurable listening experience.

Single-ended amplifiers - even using triodes - require careful speaker matching.  Many speakers are too inefficient and have wild impedance curves that require more power and low output impedances. However, the 6CB5A coupled to the Edcor iron did a decent job driving any of the speakers I have on hand.  Those into rock or heavy orchestra would benefit with more power or horn speakers, so keep that in mind if you're interested in building something like these amplifiers.

Wednesday, April 3, 2013

Dividebytube's Guide to Building an Audiophile System

I've been into this hobby for a number of years and have gone down several dead ends.  This little article is a sort of "lessons learned" piece, which may be of some benefit to a beginner - or even an experienced - audiophile.

Consider the Source:
Like Linn, I believe having a good signal source is the most important part of any good stereo system.  Some others will tell you to spend the majority of the budget on speakers, or even the amplifier.  However, I've found a cheap CD player or turntable will just lead to heartache, making the listener chase their tail trying to find the best speaker or amplifier to match with the inferior sound quality.  Is the speaker too bright or is it the cruddy op-amp in the digital-to-analog converter?  Is the amplifier muddy or does the turntable poorly constructed, picking up vibration?  A fairly neutral source provides the foundation for good system building.

Amplifier Envy:
This idea is closely related to the first concept of source quality - don't go crazy with finding "the right" amplifier until you have nailed down your front end.  Yes, just the right amplifier does make a big difference, especially tubes versus solid-state or Class A versus Class AB, but don't worry about this aspect as much until you have sorted out the source and the speakers.  There are plenty of budget models out there that will do the job until the time is right for an upgrade.

Boom and Sizzle:
Speakers are like luggage - easy to buy and almost impossible to sell.  Before buying any speaker, consider your listening room, environment, and music likes.  For example, a small space will require a small speaker - there is no reason to excite room nodes and get a muddy sound with a monster speaker crammed inside of a tiny space.  If you have little children - a Quad Electrostat or a mini-monitor on a slender stand - may not be the best route.  And small speakers may not reproduce bass all that well, which won't work for head-banging levels, unless a subwoofer is used.

Picking an Amplifier:
I like tube amps, especially single-ended and/or low-powered ones.  Good sounding amplifiers of a higher wattage are few in number, but they do exist.  The Eico HF-60 and (rebuilt correctly) Dynaco Mark III monoblocks come to mind.  However one has to be smart enough to realize that tube amplifiers may not always be the best match for the speaker, especially if low-efficiency, wild impedance curves, or a large listening space is being used.  In this case, perhaps a bigger tube amp or a good solid-state unit is in order.  For example, matching a 20W 6BQ5 amplifier to a pair of Magnepans will lead to nothing but frustration, unless incredibly low playback levels are your thing.

The Good, The Bad, and the Feedback:
Zero Negative Feedback and single-ended was quite the rage for awhile.  However, these types of amplifiers require efficient speakers with higher impedance curves - think Altec-Lansing horns, Klipsch, or (modern) Zu speakers.  Pairing a single-ended 2A3 amplifier to a 4-ohm nominal speaker can result in some strange effects: muddy, underdamped bass or perhaps a rolled-off treble.  Some listeners may like this effect, but it isn't fidelity since the "romantic" tubey sound can dominate the music to the point where the differences between recordings becomes almost negligible.  That is to say, if every record or CD sounds the same, then you're listening to a pleasant distortion machine, not a high-fidelity amplifier.  In this case feedback - if judiciously applied - can actually help, providing speaker damping and extending frequency response.

Short Circuit:
Another strange audiophile fancy is the love for boutique parts.  Now don't get me wrong, I've personally heard differences between coupling capacitors, resistors, and wire.  But I also know that the circuit itself is the most important part, not the parts supporting it.  For example, a poorly design SRPP tube linestage isn't going to be greatly improved by slapping in a Teflon capacitor.  The circuit itself needs to be corrected, or an alternative and improved preamplifier needs to be purchased.

Flash in the Pan:
The high-end audio scene is filled with hyped products and broken dreams.  I could name company after company that have failed since the 1980s, and some of them even produced well-reviewed winners that should have seen these start ups to the road to success.  However, the audiophile market is a niche one and it's apparently quite easy to fail.  Unless you are handy with a soldering iron, my advice when purchasing equipment is to buy from established brands that have been around for awhile.  This will lead to easier service, possible product updates, and better resale value.  Some of the classic brands: Audio Research, Conrad-Johnson, Mark Levinson, KEF, Quad, etc have a long track record and the quality of their gear, plus the resale value shows this.

Vintage Madness:
I love old tube gear and vintage speakers.   However, in the world of amplifiers, only a few of the old designs really stand the test of time.  These were usually the expensive pieces back then  - Marantz, Fishers, the top-level Eicos, Fishers, Dynacos, Grommes, Fairchilds, etc.  On the other hand, the more budget integrated and console amplifiers suffer from poorer circuits, cheaper parts, and output iron with less bandwidth and smaller cores.  The same holds true with speakers - only some have really held up to the test of time, while the majority of the vintage units sound rolled-off and not very detailed.  Sure, these old-timey pieces can sound enjoyable, but they ain't hi-fi.

Separated at Birth:
If you're a simple kind of audiophile who wants the minimal moving parts, then by all means go the integrated or receiver route.  Just keep in mind that this path will minimize - unless in/out RCA jacks are included - your upgrade possibilities.  Personally I prefer separates - preamplifier and amplifiers - which allows different combinations of gear to be tried.  Difficult speakers to drive?  A tube preamplifier and a hefty solid-state amplifier might just be the perfect combination.

Budget Talks:
Even if you are silly rich, every stereo system is built around a budget.  Things to consider: how much are you willing to pay and how will it match with the rest of your system?  I could, with enough bad decisions, put together a fantastically expensive system of Stereophile Class A components that would make any listener run out of the room screaming,  For example, couple a low powered singled-ended amplifier with an inefficient speaker with a low 1-ohm impedance curve.  Though painful, it's best to start with a good front-end, and then buy and sell up the chain, keeping in mind that a manufacturer's lowest priced product is not always the best place to start.  For example it will be better to save to buy a Rega P3 than the entry-level P1.

David and Goliath:
There are giant-killers out there - budget gear that punches above its low price and gives a great listening experience.  KEF and Wharfedale speakers easily come to mind, along with some of the cheaper Chinese tube amplifiers.  However, no matter what you tell yourself, they still are budget pieces that can be surpassed with something more expensive.  It's just a matter of how much you are willing to spend and if you ears really demand that much perfection.  I think it's important not to lie to yourself and accept the limitation of your system, which brings me to my final point.

Times are A-Changing:
When buying gear and bring in a new component into the system, it's all too easy to get swept away thinking that the latest change is always for the better.  It's also far too easy to think an expensive unit will always surpass a cheaper piece.  It would also be wrong to think that newer is always better than older.  Again, system matching and careful listening is required here.  It's also good to have a few audiophile friends over who don't have an emotional investment in your stereo.  If they have experienced ears - and are of an honest nature - they can also tell you what faults they are hearing, instead of just concentrating on the best parts of upgrade.

As always, comments and suggestions are welcome.