PHI Audio | Bespoke High End










This might very well be one of the best-sounding loudspeakers you'll ever hear.

For eight years now we've impressed just about every person who has auditioned
our products. Many claim that our loudspeakers set the standard with which they compare
other loudspeakers. Our objective is to improve on that standard.




FOLDED TQWT, DTTP and  EXOLINEA® aperiodic tuned pipes.

PHI has embarked on the design and manufacture of a brand new range of tuned pipe loudspeakers. The price range of our line-up has been broadened, ranging from affordable 'desktop' and 'bookshelf' loudspeakers to our customary high-end units, in both our customer and materials driven be[spoke] series and our per[form] range, where the fidelity is largely determined by the exact form of the loudspeakers.

We have maintained our minimal Dieter Ramsian design aesthetic by using solid wood in conjunction with engineered materials. This latter will be the highest quality Birch Plywood, chosen for its appearance as much as its proven sonic qualities.

Our focus, as always, is on full and wide range loudspeakers, assisted with appropriate high and low frequency transducers where deemed necessary.



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 per[form] range will have a very 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. It incorporates a unique down firing port 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 has a much higher sensitivity of close to 95dB/2.83V.

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. 


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 performance too much. This speaker employs three identical 4 inch fullrange 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 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. Also a keeper.


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




On the work bench: The Steropes - a folded TQWT
Floor-Standing Stereo Audiophile Loudspeaker System.

Above: a concept sketch of the case of this new design.

As first offering from our new per[form] stable, this loudspeaker employs a principle which cuts down on the size of tuned pipe speakers by folding the upper part of the speaker taper behind the lower part. The upward tapering geometry of the unit not only makes for attractive looks, but ekes the last drop of performance out of the already beautifully-constructed, German-designed driver set. The loudspeaker accepts a range of drivers without needing structural modification, allowing an easy upgrade path to more exotic components.

Features include sensitivity in excess of 95dB/2.83V at 1m, an easily driven load impedance, a minimal first order filtering network and solid 30mm hardwood and birch ply construction.



Freshly off the design bench: The whEDG - a wall-mounted TQWT/reflex enclosure hybrid.
Wall-Mounted Stereo Audiophile Loudspeaker System.

Above: a concept sketch of the case of this new design.

As second offering from our new per[form] stable, the new whEDG design is a hybrid of a short-taper tuned pipe and a standard reflex enclosure. The German-designed high-end fullrange driver uses the tuned pipe character of the enclosure to firm up its lower frequency response and excursion characteristics, while the Italian-designed audiophile low frequency driver, which only operates at full efficiency between around 40Hz to 150Hz, uses the 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.

The loudspeaker is made to be mounted relatively high against a wall – this is a concession to space considerations in modern, smaller home spaces, but simulations have shown that this configuration not only has minimal effect on the sound character of the fullrange driver, but is substantially advantaged by the low frequency boost that accompanies the placement of a loudspeaker against a boundary. An upward-firing slot port 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 either birch plywood, OSB, granite or glass for the sides. Padauk and glass is depicted in the concept drawing 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.



The Future: A New Cyclops

The Future: A New Cyclops
Minimal Floor-Standing Stereo Audiophile Loudspeaker System.

Above: a concept sketch of the case of the new Cyclops.



The Future: The New phISH

The Future: The New phISH
Minimal Floor-Standing Stereo Audiophile Loudspeaker System.

Above: a concept sketch of the case of the new phISH.



Keep watching this space.





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 fullrange drivers. An almost impossible feat, we realised.

The Sonic Impact T-Amp

The initial 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 3 inch driver without using a impractically large horn.

The initial Cyclops had a 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 original was a tough act to follow. We created the downPHI® from the original Cyclops – a bit taller and sleeker and in some ways better. We went back to the original but amended the filter unit, housing many of the components inside the boxes as one has come to expect. We adapted the aesthetic to 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 easy.





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 woods for the construction of loudspeaker enclosures.

Below is a list of woods we have used, with some notes as to the tonal and mechanical character of these woods. Using tone woods for loudspeakers and in particular referring to the tonal characteristics of woods may sound alarming to those committed to neutrality in sound. 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 coloured - we, at PHI, are probably 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 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. 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.

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 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.




e-mail: information
Telephone: +27 73
848 6707
Workshop: +27 79 405 8867
Fax: +27 86 518 3482

12 Kloof Road
Gordon’s Bay
Western Cape, South Africa

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

Business hours are from 10h00 to 20h00

Bespoke High End | PHI Audio | 2018 | Contact

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