Quadrature DSP 5 Speaker review

quadrature DSP model 5

Quadrature DSP Model 5 [hiendy.com]

A review of an early DSP speaker system (1996) written by someone who knows what he’s talking about when it comes to the theoretical and technical side of things. It contains a very interesting nugget (highlighted) that answers a question I asked in my piece on building my speakers, and it includes some by-now-familiar accounts of the sound of DSP…

The Model 5 presents a startling, almost shocking amount of detail without having even a hint of excess treble. Moreover, it produces similarly startling stereo image quality. The Model DSP 5 simply vaults to near or at the top in these qualities. How is this possible? The answer seems to be in the phase linearity attainable by DSP.

Everyone knows that phase linearity above the midbass is of highly secondary importance as far as tone quality and tmbre are concerned.’ Tonally, moderate phase irregularities are essentially inaudible as far as timbre is concerned. But it is important to realize that the oft-quested researches on ‘Inaudibility of phase” in the higher frequency were about timbre only. When it comes to resolution and imaging the story could change. And I am becoming convinced that it does.

Not to head too far into theory, let’s just recall for a moment that localization of sound sources involves interaural timing differences down to a resolution level of one one-hundred-thousandth of a second. In this context, it seems unsurpnsing that time-correct behavior of speakers could be important for imaging…

…  All you have to do is listen. If your experience is like me you will be something like flabbergasted to hear, say. each individual member of large choruses standing before you, as it were. “Veils removed” is some nonsense cliche, and not really the right description. The effect is more of bringing a pair of binoculars into focus. Bingo—with focus achieved, there is the sharp picture. But the sharpness is not that of edginess, of the pseudo-detail of rising top end. This is clarity as clarity is in reality, natural but defined.

I’m fascinated by the various types of speaker cabinet that exist, this one being half way between the traditional monkey coffin and slim floorstander. Those razor sharp square edges, yet it sounds amazing – can edge diffraction be as detrimental as some say it is? It may be possible that the grille (not shown in the picture) provides a smoothly-shaped surround, but the veneer on the baffle suggests they’re meant to be used without grilles if desired.

The first time I ever heard stereo

I can remember the exact moment. My dad had tried to explain to me the difference between true stereo and just wiring up a second speaker to a mono radio – and failed. I went with him to the hi fi retailer Comet to pick up our new Tandberg receiver. Unfortunately they didn’t yet have the Tandberg speakers or Thorens record deck in stock, but we bought some Koss K6 LC headphones. That evening we attached some wires to make an FM aerial, and plugged in the headphones. My dad tuned in BBC Radio 2 – some big band programme I think – and handed me the headphones. Of course, within a fraction of a second I understood what stereo was. This would have been round about 1972-73.

vintage-tandberg-tr1010-fm-am-stereo-receiver-56-p

Tandberg TR1010

This Tandberg receiver seems to be going for a reasonable price

koss k6

Koss K6 headphones. Our version of these headphones had a slider volume control on each earcup. [www.etsy.com]

“Why the vinyl revival can sod off”

A very enjoyable article.

…I’m not really blaming vinyl as a material, or even as an inferior vehicle for the delivery of recorded music (CD has a wider dynamic range when used properly, etcetera); I’m blaming it as a signifier, as a loaded totem of rockist bullshit…

Every time someone eulogies vinyl, they seem to necessarily slag CDs at the same time, and in the process of doing that they’re voiding the cultural experiences and values of a large swathe of music fans.

A 7Hz Wall of Bass

A wall of bass…

Quite an interesting story here.

Powersoft D-Cell504 IS high power amplifier modules have been specified to drive a unique ‘Wall of Bass’ in an Austrian nightclub — as low as 7Hz….

…For the rear wall, behind the 6 x 5 meter stage, 400 kg special concrete blocks were cast and set into a 6 x 3 metre wall, using 13 tons of heavy concrete and a further 35 tons for the foundation — requiring a monumental effort… 

…Each concrete block serves as loudspeaker enclosure with pressure-resistant rear chamber which implements the perfect impulse response of a ‘closed-box’ design and maximizes the radiation resistance of the woofers through the acoustically hard surface. …

 …“A perfect plane wave is created in the interior of the club, which naturally moves along the side walls and doesn’t induce any room modes. The rear of the main floor was converted into a single bass trap to absorb the incoming wave. …

…“such an operating range and evenness of the low frequencies is overwhelming”…

…Powersoft were able to deliver 25,600 watts amping power, including 4in voice coil with custom made venting system using hardened membrane….

…“The data we measured melts in one’s mouth,” summarised Reinhard Nell. “The sound pressure level is beyond 140dB and absolutely equal at any point in the room (not that anyone would need such sound pressure levels). And you don’t have the possibility to feel 7Hz throughout your whole body every day.” Summing up, Steffen Kroschel says that everyone who has played through the system has been hugely impressed. “For some it has changed their awareness of music.”

What does a DSP active system sound like?

Legend Acoustics Tikandi

It looks as though the Legend Acoustics Tikandi system is pretty much an ideal speaker by my criteria (sealed enclosure, active DSP crossover & correction). The following extracts are from this review:

…DSP works so well it has ruined me for anything else…

…I’ve barely listened to my system in the many months since the Tikandi system left my room. At the next CES I attended, with a few exceptions, I could barely sit through most of the demos because I had grown so accustomed to the natural and lifelike sound of the Tikandi system. Everything sounded broken to me….

…There was a vividness and palpability to the presentation that was unlike anything you will likely hear without the benefit of DSP. The localization of not just instrumental images but also ambience cues brought not just the music to life but brought the entire event to life. A “you are there” quality would transport you to the recorded space in a remarkably seductive way…

…The phrase “instruments well placed within the sound stage” doesn’t even begin to describe what I heard. Each instrument became distinct in a whole new way. One of the advantages of DSP, and I think this has mostly to do with correcting the phase response, is things just come into focus in a way that only happens in the most expensive, most painstakingly set up systems (which includes dealing with the room acoustics)…

…The bass was exceptionally well defined with an almost luminescent quality. It was at the same time both thunderous and well controlled creating some of the best bass I’ve ever heard in my room. In fact the bass drum on this recording didn’t even sound like the same instrument I had been hearing… so many nuances were revealed that had been previously masked…

Technology is Finally Delivering its Promise

I think there is a misunderstanding about cutting edge technology of the past: we assume that the people back then didn’t notice the flaws that are so obvious to us now. We look at old photographs, television programmes and magazines and our reaction is to laugh at how naive everyone looks as they ooh and aah over some primitive gadget as though it is technology from another planet. But the thing is, I am now approaching an age where it is the years of my childhood (the 1970s) that are receiving this scrutiny, and I can tell you that we really weren’t as naive as we looked!

Technology has always aspired to be like science fiction, but the exterior casing has often been just a thin veneer barely concealing the workings within. The whole has almost always been let down by the most mundane of practical details. Sometimes these were unavoidable limitations of the technology at the time, but as often as not they were manufacturers’ attempts to make the product as cheap as possible – and going too far. In some cases, manufacturers identified a component that they thought was too expensive and substituted a ‘token’ replacement that sort-of looked like the original but simply didn’t work. They might just as well have not bothered, and instructed the customer to turn their calculator on and off by removing and replacing the batteries – it would sure as hell have worked better than the bit of springy oxidised metal attached to the calculator case with a splodge of molten plastic ‘rivet’ which invariably lost contact mid-calculation.
Looking back, I can remember the following gadgets that revealed glimpses behind the ‘magic’ which rather spoiled the whole thing.

Hacker FM valve radio in the 1960s – FM was a better replacement for AM: much higher quality and less affected by interference from 1960s vacuum cleaners (see later!). What a shame that so much as breathing on the volume control triggered a veritable thunderstorm of rumbling and crackling from its large internal speaker.

TV – our common or garden television of the time was black and white and despite a stylish appearance, you could not miss the smell of hot dust (probably asbestos!) that emanated from the vents in the pressed fibre rear cover. The worst part was a vicious rotary channel selector that took great effort to operate and hurt your fingers with sharp corners. Like the valve radio, it needed ‘burnishing’ upon every operation to avoid a noisy picture, and the ‘set’ required frequent banging on the sides with a clenched fist.

Vacuum cleaner – at this time the housewives of Britain were probably still in the first bloom of romance with gadgets such as this. But to a child the vacuum cleaner was terrifying: unbelievably noisy, with a strange cloth bag that inflated as though alive. And the worst thing of all: when in operation anywhere in the house, the TV picture was obliterated under a blizzard of noise. Also, ‘the belt’ needed frequent replacement, so everyone was familiar with the mechanism that coupled the motor to the rotary brush, no matter how slick the styling on the outside.

Cassette recorder – into the 1970s, technology became smaller and cheaper. But still the user was forced to confront what lay behind the attractive (or not) exterior. Readers of a certain age are bound to be familiar with those devices that featured wafer thin ‘brushed aluminium’ fascias and foul slider controls. The sliders were particularly nasty, and were cheap plastic substitutes for the slider controls found on professional products. To make them feel better, they were liberally gunked with grease that migrated onto the fascia, attracted dust and grit and caused the knob to loosen and fall off. The fascia, a substitute for a brushed aluminium panel was not much thicker than foil and was glued down onto the flimsy plastic chassis. Inevitably at some point, the aluminium began to peel off at the corners. The screen printing on the surface wore off easily. This form of exterior styling was a ‘box ticking exercise’ and nothing more. The manufacturer knew it was an abomination, and they knew that the customer knew it was an abomination.

In many cases, the exterior casing was just a slight, symbolic smartening up of a primitive technology that was plainly still on display. The little digital counters in tape recorders comprised cylinders with digits printed on them that engaged with a worm gear, and a button was provided to zero the counter in a rather abrupt fashion. Despite hiding them behind the front panel with a small window to see the digits through, it was always completely obvious what was going on, so although it was symbolic of a ‘digital display’ the user was burdened with knowing exactly how it worked. The heater controls in cars were in a similar vein: sliders that could sophisticatedly blend hot and cold air, and adjust airflow, but unfortunately connected the user directly with the mechanism beneath. You felt and heard the friction of flaps opening and closing, and the clicking of the three position switch that purported to give you infinitely variable control.

It wasn’t just consumer gadgetry that revealed its inner workings. Viewers of classic films will be familiar with the way you always knew when a fade was coming: there was maybe a click on the the soundtrack, and then the image became grainier and dustier just before the fade. It was as though the fade itself was symbolic, and the practical details of how it looked were secondary. The 1970s were also the heyday of ‘chromakey’ the miraculous television technology that enabled an actor or presenter to sit in front of a blue background and find themself flying, or about to be eaten by a giant ant. But even as a sub-10 year old, it never ‘fooled’ me. It was, again, a symbolic technological miracle where the actor/presenter had a rough blue halo around them that always gave the game away, even if the lighting and colours were matched reasonably well (which they most often weren’t).
Computers came onto the scene, and in terms of concealing their innner workings, nothing changed! In fact they were almost comical in the way the user was connected directly with the underlying gubbins – ‘clunky’ doesn’t begin to describe it. Operating systems became more sophisticated, the hardware became less ugly, and so on, but for a long time this looked like the same symbolic tarting up of pretty raw technology.

But maybe, just maybe, technology is now finally delivering what it always promised.

In 2001: A Space Odyssey Stanley Kubrick gave us a vision of technology that actually did conceal its inner workings. We had video screens and displays that were flat and had rounded corners, were flicker-free, and had ‘perfect’ text and graphics. In contrast in Alien ten years later, the highest tech of the future comprised evacuated glass tubes with screens that weren’t even flat, and raster scanned displays. The Kubrick vision is, without doubt, here, and Alien now looks out of date. But we are beyond the 2001 vision, because we have mobile devices with those same perfect displays, which are finally realising the idea of completely seamless technology.

Who, just a few years ago, would have predicted that the average person would be able to carry around a device that could not only direct them to their nearest fast food outlet, but could do it without an external antenna and high-capacity battery pack? Sure the basic technology existed for many years but, like RDS radio, when engineers are in charge of developing a technology, the results are often clunky and ‘arcane’. The obvious people to credit for overcoming this are Apple, but I think they were accelerating a trend in ‘design’ that had started already.

… to be continued