New December 2007

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		Download Silicon Chip Article
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		Retail :- Please Contact  Wagner Electronic Services

Build the Signature Series Kit Speakers

• Sensational sound from the JP3.0 Ribbon Tweeter & Peerless Drivers
• These new speakers kits are among the very best available
• They will be a very good match to many amplifiers, from 20 to 120 Watts.
• Design by RUSSELL STOREY of Stones Sound Studio
• The following is an excerpt from the Silicon Chip article by Leo Simpson

"These new speakers are among the very best kit speakers that money can buy. They use the very high performance Fountek ribbon tweeters and Peerless woofers". Leo Simpson. SC.

They will be a very good match to our Fountek A3500-SS Valve Amplifier.

At far right is the HD260 tower system and its dimensions. The HD360, left, uses a 6.5-inch woofer. The pick of the two systems is the HD260 because of its considerably higher efficiency: 92.5dB/1m/1W. Both systems produce commendably low harmonic distortion – measured at around 0.3% THD at 1kHz and 1 watt.

The Signature Series have been in development for over a year now and we are very pleased to present a complete set of speakers which can be used in stereo or home theatre systems.

They provide excellent stereo spread and definition, very wide and smooth frequency response with very low harmonic distortion. And while they are eminently suitable for our 20W Class-A amplifier (Silicon Chip), they can be matched up to any amplifier with a power output up to 120 watts per channel, when running normal program material.

The heart of these speakers are the very high performance Fountek JP3.0 ribbon tweeters. For those who are not familiar with ribbon tweeters, consider them as an extremely light filament of aluminium foil suspended between the poles of an extremely strong magnet. The audio signal from the amplifier is passed directly through the ribbon and the interaction of the current with the strong magnetic field deflects the ribbon back and forth to produce sound.

Incredibly, such an apparently flimsy system can produce deafening sound levels and with unsurpassed fidelity, transient response and so on.

Ribbon tweeters have been around for a long time but until recently they have been largely confined to very expensive esoteric loudspeakers systems and their reliability and ruggedness was always a litt0le suspect.

In the particular Fountek JP3.0 ribbon speakers featured here, the aluminium ribbon weighs a mere 11 milligrams and is just 9 microns thick – much thinner than the proverbial human hair!

The aluminium ribbon is 66mm long and 8mm wide and suspended between the poles of a Neodymium magnet with a gap flux of 0.6 Tesla.

As you might expect, such a short piece of aluminium represents a very low resistance and it cannot be driven directly by any normal audio amplifier. Hence, the tweeter has an integral matching transformer with a frequency response to 120kHz. This results in a very flat tweeter impedance of 7W from 1kHz to 40kHz. The basic tweeter is also extremely efficient and in fact, is used with resistive
attenuation to match the Peerless woofers used here.

Two separate stereo pairs of loudspeakers are presented, the Signature Series HD260 and HD360 systems. In addition, a centre channel variant of the HD260, the 260C was designed to complement the 260 and 360 for high-end Home Theatre A/V systems.

Shown painted version of Bare MDF Models [MDF] Paint not included.

Depending on your budget, you may decide to build either the HD260s or HD360s for a high performance stereo system. Alternatively, for high-end Home Theatre
A/V system, you may decide on a mix of the HD260 (front) and HD360 (rear) together with the HD260C for the centre-front channel.

The overall frequency response of the Signature Series HD260 and HD360 speakers is commendably flat to below 50Hz. This is the response of the HD260. Whichever approach you take, you can be sure that you will be getting a sensational speaker system. Make no mistake, these ribbon units are the finest tweeters we ever heard. They are so clean in their definition and the pin-point localisation of instruments in a stereo spread has to be heard to be believed.

On top of that, these speakers have very low distortion – measured at around 0.3% THD at 1kHz and 1 watt.

HD260 & HD360

The HD260 is a small tower speaker using the Fountek ribbon tweeter and two Peerless HDS 832873 5-inch mid/range woofers. This uses a Nomex paper cone, a very large ferrite magnet and neoprene rubber roll surround. The HD260 system has exceptional efficiency of 92.5dB/1m/1W and will provide very good volume levels from the SILICON CHIP 20W class-A amplifier, even in large rooms.

Visit Tymphany website for details: www.d-s-t.com.au

The HD260 is a MTM (midrange-tweeter-midrange) arrangement (also known as D’Appolito) with a rear bass reflex port. The HD260C centre speaker is identical in
every respect except that the tweeter is rotated through 90°, so that it will be vertical when the cabinet is laid on its side.

The smaller HD360 bass reflex system uses the Fountek ribbon tweeter and Peerless 830883 6.5-inch midrange woofer, also with a rear port. Its efficiency is somewhat lower but still quite respectable at 87.5dB/1m/1W.

Both speaker enclosures were developed using LEAP

Both crossover networks are built onto the same PC board and are presented as shown here. There is no assembly work to be done. You just install them in the cabinets and connect ’em’ up.

5 wave diffraction analyser and FFT vibration analysis software. The resulting enclosures have a Butterworth low pass filter response to ensure optimum bass and transient response.

While the enclosures are relatively small, they are very strong and rigid to ensure very low panel resonances. They are made from 18mm MDF (medium density fibreboard) while the baffle is made from two thicknesses (36mm), to allow the ribbon tweeter to be flush-mounted and still provide maximum rigidity.

In addition, the inside edge of the woofer holes are chamfered to prevent diffraction effects at midrange frequencies and the HD-260 has internal bracing of the large
side panels.

More Graphs See Developers Website

Rear bass port

Both enclosures employ a rear port to ensure a reduction of overall driver distortion and cross-modulation which can be generated by front ports. According to the designer, with a front port a form of speaker (low frequency) distortion and cross modulation is generated by the compressed air exiting the port out of phase with the woofer creating (modulation) interference of the woofer cone. This interference of the woofer cone occurs at medium to high playback levels (port velocity) and is one of the factors reducing overall dynamic range or head-room of the transducers
and speaker system.

The port itself is 63mm in diameter with small flared ends. All this is done to keep distortion at a minimum.

Crossover networks

Using the best drivers and a carefully designed cabinet  would be a waste of time without an equal standard in the crossover networks. In the Signature Series the crossover networks are quite complex (Linkwitz Riley with Bessel / Butterworth response). They were developed to enable good linear phase and minimum distortion through the passband and overlap regions of both the woofer and ribbon
tweeter.

They have been developed with bi-wiring in mind so the tweeter and woofer filter networks are essentially quite separate, as shown in the diagrams of Fig.1

The tweeter is fed with a third-order high pass (18dB/octave) filter and the woofer is fed with a second-order (12dB/octave) low pass filter. In the case of the HD-260, the crossover frequency is 3.8kHz and 3.2kHz in the HD-360.

Both crossover networks are based on the same PC board but there are differences. Each crossover network employs air-cored inductors, non-inductive wirewound resistors and 400V metallised polyester capacitors. High quality
components are used throughout.

Building them

The designer of these Signature Series loudspeakers has been very particular in specifying how everything must go together, from the initial specification of the drivers, down to the very last detail of the cabinets, crossover  components and even oxygen-free copper wiring.

This very fine attention to detail on the part of the designer has made the task difficult for the kit supplier but it means that you, the ultimate kit-builder, will have an easy time putting them together.

The loudspeaker cabinets are supplied fully assembled in two forms, unfinished MDF or black vinyl. In the case of the unfinished MDF cabinets, it is up to you as to how you finish them.

The prototype cabinets featured in this article were spray-painted to a very high standard. If you have access to a high-pressure spray gun and spray booth, so much the better.

Alternatively, if you intend painting them, we recommend using a roller, to avoid leaving brush marks – it is amazing how brush marks can catch the light and become noticeable, especially if gloss paint is used.

Not only are the cabinets fully assembled but they also come fully lined with a grey felt, to damp internal reflections and they are also supplied with the fully finished grille cloth frames.

For further details, see the downloadable article and/or instruction manual.

Bi-wiring option

Just back-tracking for a moment – if you intend running these speakers are bi-wired, with separate stereo amplifiers driving the tweeters and woofers, then the installation procedure is slightly different. You need to cut links LK1 and LK2 on the crossover PC boards and then remove the gold plated links from the 4-terminal panels.

Making your own enclosures

If you want to save some money by building your own enclosures, all the necessary dimensions and other information is accessible on the designer’s website at www.stonessoundstudio.com.au

If it was our choice, we would pick the complete kits rather than going to all the trouble to make the cabinets. Sure, you will save some money but there is a great deal of work involved. Consider that the front baffle needs to be laminated from two 18mm sections and you need to make the bass port with its carefully flared ends.

There are really no short cuts to making the cabinets and if you don’t follow the diagrams very closely, you will prejudice the sound quality. The above site has all the information on these speakers so if you want to check any aspect of the design, you can readily do so. SC

KIT AVAILABILITY

Fountek ribbon speakers, Peerless speakers and all of the kits for the Signature Series are exclusive to:

Wagner Electronics,
138 Liverpool Road,
Ashfield, NSW 2131.
Phone 02 9798 9233
Fax 02 9798 0017.

Website: www.wagner.net.au

COSTS [RRP]

Include speakers, cross overs, all hardware and cabinets with speaker grill, etc.
(Prices are Recommended Retail and per pair [except 260c] including GST).

KIT 260

• Plain MDF ........... KIT260-MDF............................... $1299.00
• Black vinyl ........... KIT260-BV ................................. $1399.00

KIT 260C (C=Centre Chanel : One unit only)

• Plain MDF ........... KIT260C-MDF .............................. $649.00
• Black vinyl ........... KIT260C-BV ................................. $719.00

KIT 360

• Plain MDF ........... KIT360-MDF .............................. $1159.00
• Black vinyl ........... KIT360-BV ................................. $1299.00

SPEAKER KITS (without cabinets)

Include speakers and crossovers but no cabinets, cloth grills and hardware.
(RRP per pair [except 260C] including GST).

• 260 Kit ................. SPK260........................................ $799.00
• 260C kit................ SPK260C (one driver only)....... $399.00
• 360 kit.................. SPK360......................................... $699.00

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