VIAWAVE GRT-145W-4
VIAWAVE GRT-145W-4 — Ribbon Tweeter with Waveguide · Ribbon / Planar Magnetic
98 dB - 4 Ohm - 1,800 – 30,000 Hz - 17 W RMS
Part no.: 42A-CHS-BT-VIA-0005
Documents
VIAWAVE GRT-145W-4 — Ribbon tweeter with waveguide
Waveguide version with 4-ohm winding — 98 dB at 2,83 V and controlled dispersion.
98 dB sensitivity · 4 Ω · Frequency range 1.800 – 30.000 Hz
What the SRT technology does
In a classic ribbon tweeter the air gap between ribbon foil and magnet poles is open. Viawave seals it with a U-shaped, heat-resistant polymer film — the patented SRT technology (Sealed Ribbon Tweeter). Two things follow: distortion at the lower end of the range drops markedly, and sensitivity rises by 2 to 3 dB. For a ribbon with only 7 cm² of diaphragm area, 98 dB is an unusual figure.
Technical data
| Nominal impedance | 4 Ω |
|---|---|
| Recommended frequency range | 1.800 – 30.000 Hz |
| Sensitivity (2,83 V / 1 m, 2 – 10 kHz) | 98 dB |
| Power handling, RMS | 17 W |
| Power handling, peak | 40 W |
| Programme power (high-pass 3.000 Hz, 12 dB/oct.) | 150 W |
| Rear chamber resonance | 900 Hz |
| Ribbon dimensions | 14 × 50 × 0.009 mm |
| Ribbon area | 7 cm² |
| Ribbon mass | 0,018 g |
| DC resistance Re | 0,06 Ω |
| Inductance (low frequency) | 3,5 mH |
| Inductance (high frequency) | 0,017 mH |
| Flux density in the gap | 0,65 T |
| Net weight | 1,43 kg |
Materials
| Ribbon | Aluminium |
|---|---|
| Waveguide | Aluminium |
| Magnets | NdFeB |
| Magnetic circuit | Low-carbon steel |
| Rear chamber | Natural wool |
Use
Der Hersteller gibt einen Hochpass ab 3.000 Hz mit 12 dB/Oktave an. Tiefer trennen geht mit der Waveguide-Version leichter, weil der Wirkungsgrad im unteren Bereich höher liegt. Die Belastbarkeitsangabe von 150 W gilt ausdrücklich nur mit dieser Weiche — ohne Hochpass ist ein Bändchen sofort zerstört.
The manufacturer's datasheet with frequency response, impedance and distortion measurements is available for download above. Part no.: 42A-CHS-BT-VIA-0005
Viawave GRT-145W-4: ribbon tweeter with waveguide, 98 dB at 4 Ω and controlled dispersion
On the Viawave GRT-145W-4 an aluminium waveguide sits in front of the sealed ribbon. That changes two things compared with the flat-faceplate version: dispersion becomes controlled, and efficiency at the lower end of the range rises – which is why Viawave quotes the 98 dB (2.83 V/1 m) for this version over 2 to 10 kHz rather than the upper band. The 4 Ω winding delivers 3 dB more at the same voltage than the higher-impedance variant; that is a voltage advantage, and the amplifier has to supply the current for it.
Underneath the waveguide is the familiar SRT technique: the air gap between aluminium ribbon and magnet poles is sealed with a U-shaped, heat-resistant polymer film, which lowers distortion at the bottom end and adds 2 to 3 dB of sensitivity. Ribbon 14 × 50 × 0.009 mm, 0.018 g, 7 cm² area, NdFeB magnets with 0.65 T in the gap, operating range 1,800 to 30,000 Hz. With the waveguide the driver weighs 1.43 kg.
Use and enclosure
A waveguide in front of a ribbon is above all an answer to the crossover frequency. Because efficiency is higher at the lower end, the GRT-145W-4 is easier to cross lower than the version without a waveguide – the manufacturer's spec remains a high-pass from 3,000 Hz at 12 dB/octave, and only with it does the 150 W program rating apply. Heading towards 1,800 Hz means a steeper slope; RMS rating 17 W, peak 40 W, chamber resonance 900 Hz. Without a high-pass the ribbon is gone instantly.
The second benefit: the dispersion fits a midrange that is already beaming at its upper end, so the transition does not show up in the room as a step in the power response. Passive crossovers are calculated from the impedance curve – 0.06 Ω ribbon, 3.5 mH low-frequency and 0.017 mH high-frequency inductance at the transformer, 4 Ω nominal. The amplifier must drive 4 Ω loads stably, especially if the midrange is low-impedance as well.
What to look out for
- 4 Ω – amplifier rated for 4 Ω; check total impedance in parallel crossover branches
- Aluminium waveguide: controlled dispersion, more efficiency at the lower end
- High-pass 3,000 Hz / 12 dB/oct as spec – 150 W program only with it
- 1.43 kg – allow for depth and weight when mounting in the baffle
- 98 dB measured 2–10 kHz – do not confuse with the measurement band of the flat version
Frequently asked questions
What does the waveguide on the GRT-145W-4 actually do?
More level at the lower end of the range and a defined dispersion. Both make integration with a midrange easier: you can cross lower and get a more even transition in the room.
Which amplifier for the 4 Ω version?
One that drives 4 Ω continuously. The 98 dB at 2.83 V results from double the power draw compared with the higher-impedance winding; a valve amplifier with a 4 Ω tap works, as does a solid-state amplifier rated for 4 Ω.
GRT-145W-4 or the higher-impedance waveguide version?
Same ribbon, same waveguide, same operating range. The 4 Ω version delivers 3 dB more at the same voltage; the higher-impedance version is the less critical load for passive crossovers and most amplifiers.
Viawave GRT-145W-4: manufacturer, spellings and classification
Viawave (Viawave Audio) is the maker of the patented SRT ribbon tweeters with sealed air gap. The GRT-145W-4 is a ribbon tweeter, available from 42.audio, Viawave dealer in Germany, with datasheet and full specifications in the driver database.
At 42.audio you get the VIAWAVE GRT-145W-4 with all key data in the driver database. More drivers from this manufacturer: Atlas Viawave.
Specifications
| Allgemein | |
|---|---|
| Manufacturer | VIAWAVE |
| Category | Ribbon Tweeter |
| Series | GRT-145 |
| Impedance (Ω) | 4 |
| Power handling (W) | 17 |
| Sensitivity (dB) | 98 |
| Frequency from (Hz) | 1800 |
| Frequency to (Hz) | 30000 |
| Abmessungen & Korb | |
|---|---|
| Weight (kg) | 1.43 |