PHI Audio | Bespoke High End









This tiny three-inch 60W speaker might well be one of the best-sounding loudspeakers you'll ever hear.

Since we have opened our doors in 2007, we have impressed almost every person who has auditioned our fullrange-driver* loudspeakers. Many claim that what they had heard has set the standard with which they compare all other loudspeakers. Our objective is to improve on that standard.

* PHI exclusively employ single fullrange/widerange drivers to reproduce the bulk of the audio spectrum between 50 and 20 000 Hz. On occasion, a supplementary bass driver might be used for frequencies under 150Hz.





TQWT, DTTP and aperiodic T8WP tuned enclosures.

PHI has embarked on the design and manufacture of a brand new range of tuned pipe loudspeakers. Our focus has now broadened to include two wall-mounted loudspeaker models. The Serpula Stereo system comprise a high-end widerange driver, augmented in the lowest octave by a very accomplished, up-firing mid-bass driver. The Serpula SESSS* system utilises the same two drivers, but here a single enclosure acts as a stereo loudspeaker pair by using wall reflections of two side-firing drivers to create an immersive stereo sound field. The result is as spatially convincing as it is tonally accurate. Both systems come in attractive tapered transmission-line enclosures, constructed from a thoroughly researched and vetted combination of solid hard tonewoods with two types of engineered materials.

We have maintained our minimal Dieter Ramsian design aesthetic by employing the simplest construction possible, using every resource as honestly and economically as possible. The result is a surprisingly affordable entry into the world of high-end loudspeakers, with aesthetics as at home in a showroom or gallery as they are in a living space.

* Single-Ended Single-Soundfield Stereo


Entry Level: The Cyclopsrevisited

More than a Taste of the High-End – but on a Budget

A sketch of the baby Cyclops.

In the spirit of the original Cyclops comes this very basic widerange-driver bipolar loudspeaker. Its entry-level form employs a front and back of solid hardwood and painted OSB laminate sides. It has no base, but uses the floor to complete the enclosure. Driver choices are made to reflect the budget intention, but forfeit very little if anything when it comes to performance. One might expect slightly lower efficiency than more expensive driver choices would provide, but an upgrade path ensures that higher-efficiency drivers can be fitted without at all having to modify either the enclosure or the crossover.

Features include full-range operation from 160Hz to 20kHz, with bass extending to under 45Hz at ± 3dB, sensitivities ranging from 82dB/2.83V to 90dB/2.83V at 1m, 20W to 50W noise power handling, an easily driven load impedance, and a minimal first-order filter network.

The RRP is aimed at just over R10,000.00 per loudspeaker pair for the no-frills option.



On the work bench: the Serpula and Tylodinatwo tapered transmission-line loudspeaker ranges

Boundary-mounted Loudspeaker System

The beautiful sessile marine tubeworm that lends this loudspeaker range its name.

A sketch of the enclosure of this new design.

The name Serpula derives from a genus of calcareous marine tubeworms. It was chosen to indicate the fact that this entire range of loudspeakers has been optimised for mounting against a boundary or wall. The first example was an event loudspeaker, aimed at professional sound reinforcement. It has been followed by a range of similarly styled designs for high-end home audio use. Construction materials for the top, face and back comprise a laminate of solid 25mm Padauk with MDF, and the sides are made of similarly reinforced OSB. The downward-tapering geometry is purely functional and a set of two carefully selected drivers, one a widerange unit and one a supplementary low-frequency driver, will complete the picture. Features include full-range operation from 100Hz to 20kHz, with bass extending to under 40Hz at ± 3dB, sensitivities ranging from 91dB/2.83V to 97dB/2.83V at 1m, 40W to 350W noise power handling, an easily driven load impedance, and a minimal first-order filter network.

The Tylodina, named after a sea mollusc, is identical to the Serpula models except for the fact that they employ a tuned port in lieu of the tapered, resistive terminus of the Serpula range. All care is taken that the use of a tuned port does not produce the excessive group delay that this type of alignment has sadly become known for. The Tylodina makes it possible to use drivers that would be too problematic to optimise in the generally larger Serpula enclosure.

RRP = R33,886.00 (for the standard model – RRP is calculated according to size, driver choices and build details, and may vary)





PHI has taken a step into the relative unknown by developing and manufacturing a range of single-soundfield-stereo loudspeakers. Already in the nineteen seventies, the late Ted Jordan of Goodmans fame had suggested an unorthodox placement of a loudspeaker pair. This amounted to placing two loudspeaker boxes back-to-back in front of the listener, with the main drivers of these boxes firing sideways, away from the speaker pair and perpendicular to the listening axis. The resulting expanding wavefronts are intercepted by two reflectors placed some distance from the back-to-back speaker pair, reflecting them at the listener.

When correctly approached, a considerable widening and deepening of the stereo field is the result, and the typical hole-in-the-middle effect of traditionally placed stereo pairs is avoided.

Our latest range takes this concept a little further by combining the stereo pair in a single enclosure, while adopting a number of strategies to ensure that whatever channel “crosstalk” there is is limited to the frequency ranges where this is inevitable, i.e. below the Schroeder frequency, especially when employing a traditional stereo pair in a typical listening environment.

We by no means intend to replace traditional stereo loudspeaker arrangements, but SSS has a number of very attractive qualities that simply have to be experienced to be appreciated. In fact, SSS often provides a more convincing and accurate representation of the sound as it would be experienced in the particular performance venue where it was recorded. Add to this the fact that the cost of a stereo set is reduced considerably, and that it is often easier to optimally set up a single speaker in a room than a pair, especially in smaller spaces, and this type of setup soon becomes an attractive proposition.




Freshly off the design bench: The Serpula SSS (single-soundfield stereo) - a wall-mounted transmission-line/aperiodic enclosure hybrid.

Wall-Mounted Stereo Audiophile Loudspeaker System.

The prototype of the new Serpula Single-Soundfield-Stereo loudspeaker, installed in a client’s lounge.

As second offering from our new per[form] stable, the new Serpula design is a hybrid of a short-taper tuned pipe and an aperiodic enclosure such as the Dynaco A10 employed.

The German-designed high-end widerange driver uses the tuned pipe character of the enclosure to firm up its lower frequency response and excursion characteristics, while the American- or Italian-designed audiophile low frequency driver, which only operates at full efficiency between around 40Hz to 150Hz, uses the aperiodic reflex characteristics of the enclosure to firm up its low-frequency response. A high-quality, low-slope, first-order serial crossover filter assures immaculate integration of the two drivers.

Rather unusually, the fullrange drivers fire sideways rather than forward, depending on reflections from equidistant walls or special reflectors to create a stereo field. This arrangement, pioneered by no-one else than Ted Jordan of Goodmans fame, produces a huge and surprisingly detailed and convincing sound stage.

The loudspeaker is designed to be mounted anywhere from ear height to relatively high up against a wall – this is as much a concession to space considerations as to inevitable boundary fall-off in modern, smaller home spaces. Simulations have indicated that this configuration not only has a positive effect on the sound character of the widerange driver, but is substantially advantaged by the low frequency boost that accompanies the placement of a loudspeaker against a boundary. The upward-firing low-frequency driver (in the case of the two-loudspeaker stereo set) augments this boost effect by acoustically coupling with the ceiling.

The design employs solid hardwood for the face, back and top of the loudspeaker, and an OSB/MDF sandwich for the sides. 25mm of solid Padauk wood, reinforced with a 9mm layer of MDF, was employed in the example above.

The loudspeaker has been tested with a range of drivers in various cost brackets and performs exceptionally with all of the drivers we have selected. This not only allows customisation, but makes possible an entry-level model of this hugely enjoyable and musical loudspeaker.

RRP = R19,210.00 (for the standard model – RRP is calculated according to size, driver choices and build details, and may vary)




Our flagship Voigt Pipe, the Cyclops’s larger cousin, Yggdrasil, is back – simpler, more powerful, markedly better than before.

Floor-standing Stereo Audiophile Loudspeaker System.

A concept sketch of the shell of the new Yggdrasil.

As minimal as we can dare to be, the Yggdrasil now accepts a range of drivers, not just the little 3-inch Kevlar driver that one has become accustomed to. The aesthetics reflects our recent approach, as evident in the Serpula range: every aesthetic decision is based on a technical reason. Not a single aspect has not been rethought a few times, and every change was tested to exhaustion. If you have the space for 2m tall Voigt Pipes, this is the best that PHI offers.

RRP = will be strongly dependent on driver choices and will start at around R13,000.00 a pair for the basic 3-inch bipole to more than R250,000.00 for no-expenses-spared boutique driver loudspeakers.


Above: The quite magnificent Cube Audio F8 Magus driver partners exceptionally well with the new Yggdrasil.




Reimagining the Past – PHI’s Loudspeaker Upcycling Project

Expanding the augmented widerange-driver idea to damaged or abandoned speakers

To follow: an image of the re-imagined JPW P1.

When a client’s old but trusty set of JPW P1 loudspeakers landed in our workshop, it was hard not to start fiddling around with drivers. Soon it had a 3-inch Tang Band driver instead of the tweeter it came with, and a modified crossover to suit the new alignment. Not long after, the tweeter was back, now as an upward-firing supertweeter, crossed in at 25kHz. It sounds so good that we have decided to add loudspeaker upcycling to our work portfolio.

Please enquire at if you have a set of speakers you want new life blown into.




be[spoke] GALLERY



Below is a display of bespoke loudspeakers we have designed and manufactured for specific customers.

Ranging from super-detailed 3 inch driver systems to heftier 2.1 meter tall 6.5 and 8  inch driver high-sensitivity loudspeakers, this abbreviated list gives an indication of our styles and capabilities.



Cyclops MLTQWT -  2007

High-detail bipolar audiophile loudspeaker system.

The Cyclops was our inaugural be[spoke]  loudspeaker. Medium sensitivity (90dB/2.83V) serial filter network plus line level response filter with a modest power handling of 40W RMS per loudspeaker unit.

This loudspeaker was very well received by the media and still acts as a  benchmark for our larger loudspeakers.

Our be[spoke] range will have a similar loudspeaker soon.



downPHI® MLTQWT -  2008

High-detail bipolar audiophile loudspeaker system.

The downPHI® was a simple evolution of our Cyclops loudspeaker - mainly to simplify construction and to incorporate the filter network into the loudspeaker enclosure. The loudspeaker uses a unique down-firing terminus to effect omni-directional loudspeaker port output.

The performance, both objectively and subjectively, was very similar to that of the Cyclops and the small differences between the two types have at times appealed to some listeners and at other times made almost no difference to their impressions.



Naledi DTTP -  2009

Ultra low bass audiophile loudspeaker system.

The Naledi was our first foray into Double Taper Tuned Pipe (DTTP) territory, a system devised by PHI to obtain a larger tuned length than a typical ceiling would allow, in order to exact very low bass performance from modestly sized 5.5 inch drivers.

Bass response extended into the high teens of Hz at around 90dB/2.83V sensitivity and 35 Watt power handling.

This speaker formed the base of our current Siderium be[spoke] loudspeaker.



Yggdrasil MLTQWT -  2009

High-sensitivity dual-cone audiophile loudspeaker system.

The Yggdrasil is our second largest loudspeaker to date, standing 2.1m tall. It employs the same port system as the downPHI® but employs an Audio Nirvana driver to attain a sensitivity of close to 95dB/2.83V – making it an ideal partner to 5 to 40 Watt valve amplifiers.

Power handling is a still modest 30W RMS per speaker, belied by its authoritative and liquid delivery, even when powered by flea-power 5 Watt valve amplifiers.

It will be superseded by our new Cyclops loudspeaker. 



phISH ISHTQWT -  2010

Affordable audiophile loudspeaker system.

The phISH use what we refer to as an intensated short horn TQWT - a pipe with a relatively short tuned length using a traditional port to effect the last bit of bass extension.

What this enables one to do is to make a much shorter loudspeaker without influencing low-frequency performance too much. This speaker employs three identical 4 inch widerange drivers, two on the front baffle and one on the rear, with a neodymium silk-dome supertweeter. Sensitivity is around 91dB/Watt at a power handling of 100W RMS.

A very listenable and versatile loudspeaker on which one of our per[form] models, the e.phISH, is based.



e.phISH ISHTQWT -  2011

Extended affordable audiophile loudspeaker system.

The e.phISH is a slightly taller version of the phISH. Performance is almost identical with perhaps a slightly more extended low end (-5dB at around 47Hz instead of 50Hz).

Very listenable and matches almost any front end. Follow-ups to this affordable and flexible design will be built in the new Cyclops style.




Siderium DTTP

Ultra-Low Bass Stereo Audiophile Loudspeaker System.

The Siderium is our be[spoke] loudspeaker for the purist. Constructed from solid American walnut, it excels in any kind of music and has bass extension and clarity far beyond what would be possible with traditional designs. The unique DTTP (Double Taper Tuned Pipe) design is a world first and provides a level of realism, involvement and immediacy that compares with that of any loudspeaker, at any price point.

Concept sketch of the Siderium DTTP

This loudspeaker will in future only be manufactured on demand.


The impressive Lii FAST-8 driver works exceptionally well in this enclosure, without breaking the bank.






The Cyclops was PHI's first commercial loudspeaker. It came about after a lengthy search for drivers for a tapered quarterwave pipe, itself intended to display the virtues of the Sonic Impact T-Amp. We found that this little amplifier simply couldn't drive the ported boxes we had at hand and the intention was to build a pair of high-efficiency loudspeakers with small widerange drivers. An almost impossible feat, we realised.

The Sonic Impact T-Amp

The original Cyclops was a spare-no-expense solution to building a loudspeaker around these 75mm Kevlar drivers, able to outperform commercial loudspeakers priced up to ten times higher than our intended sale price. It was a tall order, but we pulled it off. Measuring 91dB/Watt at 1m, the efficiency couldn't exactly be called high. But it was high enough to do the T-Amp justice and it was just about as much as one could coax out of a three-inch driver without using an impractically large horn.

The initial Cyclops edition employed a wood-clad, poured-concrete base with cavities, filled with lead shot. The enclosure was entirely hand-made from a sandwich of MDF and solid Sapele Mahogany; the filter box from Beech, Panga-panga and glass. This elaborate filter and crossover box sported a custom-designed, adjustable MOSFET pre-amplifier as well as high-quality passive crossover components. Interconnects were custom designed; NOS vintage components were used. At one point we counted four rare earth metals in the design. It was, in short, a lot of hard, expensive work.

Reviews were flattering to the extent that the Cyclops is still in production.

The downPHI®

The Cyclops was a tough act to follow. We created the downPHI® from the original Cyclops – a bit taller and sleeker and in some ways better. Aside from a different port design, it was in many ways a simple copy of the original. We amended the filter unit, housing many of the filter components inside the enclosures, as one has come to expect of modern loudspeakers. We also adapted the aesthetic to reflect our current two-tone design feel.

The present incarnation of this loudspeaker is much less elaborate than the original and, predictably, sounds a bit better. But it was by no means an easy task.




Dick Olsher's Black Dahlia Website, June 2010

"I thought to slip in the Cyclops II here, a bi-pole tapered pipe, by PHI Hi-Fi Innovation as it happens to be one of the best full-range designs I have ever heard."

Jonathan Noble


"...the PHI 58.40b Cyclops is a remarkable speaker in many respects. Its application is limited, and it requires careful matching of ancillary equipment. But in the right electronic company, with music suited to its particular talents, these speakers deliver a world-class performance."

Deon Schoeman





PHI offers a number of hardwoods for the construction of loudspeaker enclosures.

Below is a list of timbers we have used, with some notes as to the tonal and mechanical character of these woods. Using solid tonewoods for loudspeakers, and in particular referring to the tonal characteristics of woods, may sound alarming to those committed to neutrality in sound. With this in mind, we invariably employ a layer of constrained viscoelastic material, bounded by some kind of engineered surface, under our solid wood exteriors.

The truth is that any material one may use for the construction of a loudspeaker has some kind of sonic signature. This does not mean that reproduction would be more coloured – in fact, quite the opposite. We, at PHI, are as committed to tonal neutrality as any audiophile, and our loudspeakers are constructed with this as our foremost requirement. But, all things being equal, one might as well know the character of the material that one chooses.

Typically we would use a hardwood for the centre parts of our loudspeakers, and engineered materials (MDF, Finnish Birch Ply, OSB) for our sides. This not only leaves a visually interesting contrast in the designs, but also provides more varied damping characteristics and consequently a slightly broader sonic signature of the sounds emitted by the enclosure itself.


An excellent value Southern African wood known for its durability, look and stability. Sonically it falls in the walnut and maple fold, with a clean and transparent sound, slightly favouring high frequencies.

African Rosewood, Bubinga

One of the best value woods that one can obtain locally. Shares some excellent tonal characteristics with "real" rosewoods such as a slightly dark and woody sound, mildly accentuating lower and middle frequencies.


Wonderfully dark wood in a medium to high price range. Similar in sound to Merbau - rich and resinous, though perhaps slightly more favouring of the upper mids than the latter ...


Beautiful strong light coloured wood that finishes perfectly. Tonally "powdery" and "midsy".


An old favourite in loudspeaker building, particularly in the form of plywood. Relatively lively sound.


Even-grained wood with similar tonal and mechanical characteristics to mahogany, favouring mids and upper mids.


Even-grained wood with similar tonal and mechanical characteristics to mahogany. Beautiful yellow colour that turns to a rich brown as it ages.


A very soft and light wood. Inexpensive, but has some surprisingly attractive patterns and a good, neutral sound.

Maple, Birdseye Maple

Probably one of the best looking and sounding lighter woods. Difficult-to-find wood with as many "eyes" as this piece, but well worth the search. Somewhat expensive. Sound described as transparent and "silvery".


Very attractive dark, resinous wood. Medium-priced but becoming rare now. Rich sounding.


Soft, light coloured wood with similar characteristics to birch. Even-grained and silky, and often used in marine-grade plywood. Relatively inexpensive. Lively sound.


Stunning reddish wood - similar to rosewoods in tone, though perhaps less rich sounding. Medium to high price.

Presently this is our cabinet material of choice.

Panga-panga, Partridge wood

Stunning, dark and very underrated wood, similar to Wenge. Tonally neutral to slightly bright, but hard and difficult to work with. Not unduly expensive, but should be.

Pau Marfim

Very nice light coloured wood with very little figuration or texture that's not particularly expensive. Dense and hard with a punchy and brilliant sound.


Inexpensive soft light wood more suitable for the inside of loudspeaker enclosures. Clean and lively sound in such an application.

Purple Heart

Even textured dense wood with an exceptional purple colour. Excellent tone wood - smooth sounding with a slight favouring of middle and higher frequencies.

Sapele Mahogany

Forward mahogany-like sound, slightly favouring middle frequencies. Excellent workability, even grain. Beautiful dark colour but with little or no figuration. Medium-high price.

American Walnut

Wonderfully figured, chocolaty brown wood with a sound similar to Maple: clean and transparent, perhaps slightly favouring mids, upper mids and highs. Somewhat expensive.


This rather expensive, exotic-looking wood is said by luthiers to have a tone similar to hard maple – balanced, but slightly favouring highs. It makes for a lively, neutral-sounding loudspeaker, but would be worth its price, even purely for aesthetic reasons.






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WhatsApp : +27 79 405 8867

Please note that this phone number is unmonitored. We do however reply to all email and WhatsApp messages.

18 Industria Road, Mansfield
Gordon’s Bay
Western Cape, South Africa


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Our operation is spread over three locations at the moment, all in the Cape peninsula. Workshop visits are therefore not practical at the present time, but will be possible to arrange by appointment in the not-too-distant future.

Business hours are from 10h00 to 20h00

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