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Spendor BC1/SP1: tonality uber alles

The Spendor BC1/SP1 were outgrowths of the BBC’s research to create monitors that could be relied upon to make reasonable judgements on the audio quality of their broadcasts. They were, in fact, pretty much identical to the BBC approved LS 3/6, themselves reissued by Sterling Audio recently with modernized drivers (and reviewed well by REG in The Absolute Sound recently).

The BC-1’s, like the original Quad ESL, were one of those brilliant designs that more or less fulfilled exactly what the designer intended. When they hit the market in the late 1960’s, they were widely considered one of the few “box” speakers able to compete with the original Quad on its own terms, that is tonal refinement and relative lack of coloration. Though like the Quads, the bass and treble were less outstanding than the midrange, while still quite serviceable (this was somewhat improved in the later SP-1).

Even today, listening tests show the BC-1 to be outstanding in the areas of its strengths. They are smooth, free of obvious tonal problems and, yes, beautiful to listen to. And, considering it’s hard to spend over $1000 for a pair on the used market, an outstanding value. So that’s it, game over, right?

Not exactly. In order to enjoy the BC-1’s (easy to do, BTW) you have to forget the literal sound presence of the concert hall. The BC-1’s give you a tonally sophisticated sound but much less of the scale, power and presence of the concert hall experience. To be fair, most relatively small box speakers do this. The scale of a concert hall just cannot be reproduced by a speaker of this type, partly because it is a speaker of this type (with a relatively point source nature) and partly that recordings (which are VERY different from reality) just don’t contain enough of this information. Unfortunately, microphone/recorder does not equal ear/ brain.

In my view, the only way to even try and approximate the scale and power of concert hall sound is to employ speakers that augment the recordings in this aspect, line sources, planars and the like. Now let’s be clear.  Speakers like this involve more of the characteristics of the listening room and of their specific radiation patterns which mix with the (limited) spatial cues present in the recording and it’s fair to say that this is not an accurate reproduction of the recording. But it results (at least to me) in a sound more accurate to the gestalt of the concert hall experience, though in a somewhat generalized way due to the leveling effect of the unchanging nature of your room acoustics.

Whether this is for better or not is a subjective decision. Some would say the recording is what it is and all we can do is to try to reproduce that limited reality as well as we can. Others would say the original sound as experienced in the hall is the only arbiter (which is BTW, the original “Absolute Sound” philosophy), whatever gives more of that impression is right even if it somewhat compromises the limited reality present in the recording. Me, I waver. Sometimes I like the let it all hang out concert hall approach and sometimes the limited but tonally truer impression of something like the BC-1. If I had to choose one, I like the idea of the concert hall impression. But I don’t have to choose, so I can have Magnepan 3.7 in one room and KEF LS-50 in the other. Hey, some people like Chocolate AND Vanilla, it’s OK, relax…

There is another issue here. The lively BC-1 speaker cabinets, though their effect is figured in and integral to the final sonic result, still produce their own sound artifacts that cloud and obscure the sound somewhat. Here the heroic efforts of the KEF LS-50 to deaden the cabinets pay dividends in terms of clarity and the concentric drivers more fully approximate a point source type of radiation pattern, resulting in a more accurate to the recording sense of the placement of images in its limited-in-scale soundstage. Though the extra warmth of the BC-1 is certainly welcome.

It must be said that the Magnepan 3.7 (reviewed earlier) planar, while not quite as tonally accurate as the BC-1, do provide a more convincing sense of scale and presence and overall convey a more realistic impression of an orchestra in a concert hall. But if tonality is all to you, the Spendor BC-1’s are hard to beat and are one of the true classics in stereo era audio.

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Keep it quiet, but here’s the Lectron JH-50 amplifier

There are some things that it’s tempting to just keep to yourself. This is a story about one such audio product.

From about 1984 to 1999, I performed repairs on tube audio gear for various clients. There are some benefits to this beyond making a few bucks outside of your day job. One of the biggest is getting to hear equipment you otherwise wouldn’t (you have to test it out to make sure it won’t fail when you return it to the customer, after all). That’s how I first came to hear the Lectron JH-50.

It looked cool and sounded excellent, but was beyond my price range at the time. It was also not that common here in the US, being designed in France by one of the legends of the French audiophile community, Jean Hiraga. Mr. Hiraga was one of the seminal figures in the tube/triode/horn renaissance in Europe through his magazine l’Audiophile, so the amp had an excellent pedigree. I was determined to keep my eye out for one when finances allowed.

My next experience with the Lectron came at a friend’s audio store, years later. He had one of these in his personal collection and we were listening to it on a number of different speakers. We both decided that, somehow, this amp seemed to make whatever speaker we hooked up sound about as well as it could sound, it just had this uncanny ability to bring the best out of whatever it fed. My offer to buy it was rebuffed, but my determination to find one was re-energized.

Perhaps the magic of the JH-50 is in the (British) Partridge output transformers (that have always enjoyed a good sonic reputation). It employs EL-34 output tubes, always a pretty sweet sounding tube and that may help, as may the use of octal based drivers rather than the more common miniature tubes. Or maybe some synergy with the circuit design and the parts used. Whatever it is, it’s one of the best medium power (about 40 watt) tube amplifiers I have ever heard. Creamy without sounding fat, clear and beautiful, and in control.

Of course, like all tube amps, it is not completely “neutral” from a technical standpoint. But our speakers and our room are not perfectly neutral either, so how the sum of the parts of the Amp/Speaker/Room interface align is always up for question. This without questioning whether a “neutral” system is really desirable in the first place (he said provocatively).

So we fast forward to about 2004. I had finally found a JH-50 on Audiogon for a reasonable price and was waiting for it to arrive when an audiophile buddy of mine, who favors the tube/horn path, called late one afternoon. In our conversation, he lamented how hard it was for him to find an amplifier he was really happy with. In an unthinking moment, I mentioned the JH-50 and how it might be worthy of his attention. Now understand, my friend can be driven when it comes to his interests, so he went out a found a JH-50, liked what he heard, found another to have a spare and told all his friends who put on full court presses to find their own. Suddenly, the Lectron’s prices on the used market seemed to shoot up. Never content to leave well enough alone, folks started having their JH-50’s modified, which made $2000 amplifiers into $3000 amplifiers. Luckily, I already had mine.

So I am almost afraid to mention the JH-50. Not that I am so egotistical to think that just a mention on my blog is all that, but hey, it happened once before…

The Celestion SL-600, first of the luxury compact monitors

Earlier, I wrote about the ProAc Tablette mini-monitor. This was a tiny speaker that used generally tried and true technology to produce a fine miniature loudspeaker. A bit later, Celestion came up with a completely different approach to the small monitor, the SL-600. The difference was the technology that was brought to bear. The acquisition of Laser Interferometry equipment allowed Celestion’s designers to examine the action of drivers and what was discovered was that most speaker drivers operated in “break-up mode” through significant parts of their ranges where different parts of the diaphragm were moving independently rather the ideal of “pistonic action”, that is, the driver moving as one piece.

This resulted in development of all new drivers for the SL-600 (and its little brother, the SL-6). The woofer looked fairly conventional, but it did benefit from the new measurement technology. But the really obvious thing was the tweeter. It sported a copper (!) dome and did indeed act much more pistonic than typical domes of the day, at least up to about 19 Khz, where its fundamental resonance resulted in a large peak. In practice, a notch filter was introduced into the crossover to remove this. The copper dome also had another effect. Since it was relatively heavy, it lowered the sensitivity of the tweeter. Enough that, had the woofer sensitivity been lowered to match, the system would have been almost impractically inefficient. So what was finally accepted was a tweeter that was around 2 db down from the level of the woofer. Keep this in mind for later.

For the premium SL-600, there were more tricks up Celestion’s sleeve, mainly involving the cabinet. It was always known that resonances in speaker cabinets had an effect on the sound, but around this time speaker designers started to seriously attack this problem. Within a few years, the Wilson WATT would come out which used methacrylic material to deaden the cabinets and cabinets generally became thicker, heavier and better braced.

Well, Celestion took a different tack. Unlike the SL-6, which employed a more normal MDF cabinet, they decided to design a LIGHTER yet still stiff cabinet using a metal honeycomb material called Aerolam, commonly used in airplanes. The idea was that the material would not store and re-release energy and what resonance they had would be high enough in frequency to be out of the most critical range. They also employed mounting plates to attach the drivers to the front baffle, further stiffening the cabinet. These plates were serrated vertically with small channels to break up sound diffusion off their surface. All in all, it must be said that they started this design off with a clean sheet of paper. So how does this speaker sound today and how successful was its design in retrospect?

One thing the SL-600 was always celebrated for was its disappearing act and disappear it does. The image is vertically challenged as are most small speakers (though not as much as the original ProAc Tablettes), but, beyond that, the images are quite holographic. Mainly, I suspect, because the boxes radiate almost no sound from themselves to confuse the imaging issue. These cabinets also do not have serious resonances that color the sound of the drivers in tonal terms, either. And this results in a clarity through the midrange that is good even by current standards.

But there is another factor, controversial at the time, less so today, that factors into the sound of this speaker. That speakers should not measure dead flat in the treble is a commonly held view today, but back in the ’80’s this was not so much the case. Remember the less sensitive tweeter we talked about earlier? Well this resulted in a response tilted down somewhat from the mids into the treble. So you had a speaker that sounded less bright and more velvety than the norm of the day due to this tilt (and truthfully, by the lack of break-up artifacts in the Celestion tweeter that most tweeters added that contributed spurious treble energy to most conventional speakers). Many listeners of the day rejected the SL-600 for this characteristic, feeling they were slow and dark. Ironically, that “problem” with the tweeter resulted in a speaker more in keeping (in my view) with a natural tonal balance on the largest variety of recordings.

Of course, there are problems here, the worst of which involves the bass/midbass. It’s extended enough for the cabinet size, but sounds a bit vague, as though the woofer runs out of low-distortion steam as you go into the mid-bass. This has the effect of making a discontinuity in the sound, instruments whose fundamentals are higher sound very clear while the lower voiced instruments can sound less so. This is not a world-shattering effect, but it’s there and the louder you play the SL-600, the more this effect can be noted.

Due to the small size of the drivers and the cabinet, dynamics are good rather than great. Here it’s hard to single out the SL-600, most small speakers suffer from this. But some newer designs its size do somewhat better in this area. There is also a bit of a sense of hollowness to the sound, I suspect from the residual cabinet resonances. This is not a severe effect, fortunately. And there is not quite the silken beauty of the best of today’s drivers here.

The intent of the SL-600 at the time was a no-holds-barred assault on the ideal small monitor. It retailed for a high price for its time, but, especially in the context of the mid ’80’s, it was pretty much a successful design. And if you aren’t too troubled by its modest failings, this is still excellent performance in many ways for a small monitor speaker even by today’s standards. Of course, if you are willing to go for the throat, you can certainly outdo the SL-600, but not for near their price on the current used market…

The littlest Pro Ac, the original Tablette or how much bass is enough?

We take for granted the number and variety of small monitors available in the hi-end market today, but it was not always so. Back in “The Day”, small speakers also had to be cheap (who would pay big bucks for a small speaker, the logic went), so you generally didn’t get well-built cabinets or premium drivers and the speakers weren’t usually very good. Unless…

You looked into the pro market at the BBC-designed LS3/5A, which was designed to be, as the Brits’ would say, a “high quality miniature loudspeaker”. It was also designed for what we would now call near field monitoring, but worked OK as a home speaker and increasingly found favor in the hi-end home audio market.

Eventually, the home audio oriented speaker companies noticed this emerging market and started to develop products to cater to it. The ProAc Tablette came along at the right time (early ’80’s) and happened to catch the eye (ear?) of The Absolute Sound magazine and its legendary editor Harry Pearson. Harry gave it a quite complimentary review and ProAc, which previously had only a minimal presence in the US market, was off and running.

After the reviews came out, I made it my business to hear them for myself. I worked in NYC at the time and took the train to the nearest ProAc dealer, a now long gone store in New Brunswick, N.J. Sure enough, quite a nice sound came out of those diminutive boxes. I wanted a pair, but never bought them for reasons lost in the mists of time. A few years ago, a pair of the originals showed up on Audiogon for a reasonable price so I righted that wrong from long ago.

The reason to talk about this speaker (besides its good sound) is its status as one of the first and best of these early mini-monitors (as they came to be called). It can be fairly said that the BBC monitor and the Tablette opened up this market to the mainstream. The premise was that they offered competitively hi-end sound for relatively low-end dollars, assuming you were willing to give up bass and high output levels.

Today, like back in 1981, it’s still amazing to hear what comes out of such small boxes, especially in terms of dynamics and loudness in a reasonably sized room. Obviously, they will not out do larger speakers in some ways, but to me they play just loud enough and have just enough bass to be fairly satisfying on these fronts.

The glory here, as you would hope, is the midrange. Even now, it does a fine job, better than many modestly priced speakers on the market today. As with most small monitors, the imaging is fairly precise, but limited in size and height. The treble is a bit accentuated, but not so much as to scream, at least when played at reasonable playback levels. The drivers show their age a bit, being a bit more rough and ready than the better drivers today. But you don’t get that quality of drivers in modestly priced speakers and you can pick up a pair of used Tablettes for around $300. This math looks good to me.

With mini monitors, bass is always the elephant in the room. Here is where their enclosure size works against the Tabs. Listening to the Decca/Fruhbeck de Burgos Albeniz Suite Espanola, the music is accented by tympani strikes. On a larger speaker (or live music) the tymp powerfully cuts through the orchestra, on the ProAc it sits back as just a component of the orchestra. But it’s there at least, and you can understand the composer’s intent. The lowest open string on the Bass is around 40 Hz and the lowest on the Cello is around 60 Hz, so the ProAc’s in a sympathetic room can at least begin to reproduce these instruments (without really capturing them in full). But it must be said that, bottom line, their approximately 1/3 cubic foot enclosure is just not large enough to get convincingly to the lowest string of the Bass.

A speaker with an enclosure volume of  around 1 cubic foot (3 times as much) is large enough to reasonably get down to that magic 40 Hz figure in room. Again, not to say that response even lower than 40 Hz wouldn’t be desirable, but it’s less of a limitation since that’s mostly the province of the last handful of pipe organ pedals, synthesized electronic music and movie soundtrack effects and the like that are not generally of major musical significance, for classical music especially.

But then again, having the frequencies below 40 Hz also helps bring out concert hall room ambience (which certainly does help create the illusion of a live music venue) and can add to the sense of power on rock music, so they can’t be ignored completely. The problem is, as you descend below 40hz, reproducing this deep bass well becomes expensive, requiring large speakers, large rooms and powerful amplifiers. Sometimes I ask myself if it isn’t more trouble than it’s payoff. But I used to own Infinity IRS V’s, so I guess my arm can be twisted on this point.

Oh well, enough bass theorizing, back to the Tablettes. You can hear why they made waves, both positive and not so positive all those years ago. I do believe that the original Tablette sounds better than the sum of its parts, an example of the magic a wily speaker designer can conjure up.

So I still like them, and with their tiny size it’s no problem to store them when not in use. I guess, truth be told, as my only speaker their limitations would be just too, errr… limiting. Even ProAc eventually increased the size of the Tablettes in their later iterations. Perhaps a comparison between the original and the current Tablette will be possible at some point.

At the end of the day, there are many larger speakers I prefer less despite their low-frequency advantages. It turns out that what the original Tabs do well is not such an easy act to follow.