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Jamo's Classic range features rounded styling which makes them appear less boxy. At left is the 2-way Classic-4, at the centre the Classic-6, and at right is the top of the range Classic-8 Jamo Classic series loudspeakers There are any number of compact hifi loudspeakers on the Australian market, but most are presented in boring black & the styling is also uninspiring. That is why it is a pleasant change to review loudspeakers which have good styling as well as excellent sound. By LEO SIMPSON 8  Silicon Chip Jamo is a longtime Danish manufacturer of loudspeakers and in the past they have produced some fairly notable avant-garde designs, some of which have been regarded as classics. Now they have a range of three compact speakers which they have named "Classic". In some ways, the name "classy" would be more apt because they really do look good while still having a conventional box shape. The new styling has been achieved by a subtle rounding of the front of the cabinets so that they look less July 1995  9 ture of these woofers is the central concave voice coil cap which in most speakers is convex. Whether this is a cosmetic feature or is there to improve the per­formance, we don't know and the literature from Jamo is silent on this point. At the rear of the cabinet which is made of 22mm custom wood (MDF – medium density fibre board), the edges are rounded while the rear panel it­self is slightly recessed. The vent for the bass port is flared but this is not a styling feature; it is there to reduce turbulence which would be mani­ fested as audible "chuffing" The cabi­ net measures 210mm wide, 460mm high and 252mm deep. Twin connector panels Fig.1: impedance curve of the Classic-4 loudspeaker system. Fig.1: impedance curve of the Classic-8 loudspeaker system. bulky than they otherwise would. As well, the top of the cabinet features a spe­cial ribbed moulding which is round­ed at the front to again reduce the apparent overall size. Combine the cabinet design with a mahogany ve­ neer finish and you have a most attractive package. We reviewed two speakers in the new Jamo series, the Classic-4 and the Classic-8. The Classic-4 is a two-way 10  Silicon Chip bass reflex system with two woofers and a central 25mm soft dome tweeter with a ferro-fluid cooled voice coil. The Classic-8 employs the same tweeter, a midrange driver and two woofers. Listed as 133mm by the manufac­ turers, the woofers in the Classic-4 have a neoprene rubber roll surround and an effective cone diameter of about 100mm. A most unusual fea- One feature that we have mixed feelings about is the use of twin con­ nector panels which are connected in parallel with gold-plated metal straps. These are incorporated to allow "bi­ wiring" Now whatever interpretation we put on this, we cannot see the point of bi-wiring. After all, if you do use separate amplifiers to drive the bass and mid­range drivers you cannot use an elec­tronic crossover because the existing passive crossover components in the speaker are still in circuit. And if you can't use an electronic crossover, there is no point in using separate amplifiers because there is unlikely to be a reduction in intermodulation which, after all, is the main reason for using electronic crossovers and multiple amplifiers. To add further illogic to this discussion, the larger three-way Classic-8 speakers can only be bi­wired not tri-wired. So while we approve of the large gold plated binding post terminals which will take very thick cables, we don't go along with the bi-wiring fea­ture. The crossover frequency for the Classic-4 is 2.2kHz and its sensitivity is 90dB/W/m. The system is nominally 4W impedance although as the impedance curve of Fig.1 shows, the natural impedance is closer to 6W. The curve shows the conventional double peak of a bass reflex system plus the rise and fall in impedance at around the crossover frequency. Classic-8s While the Classic-4s are intended to be mounted on stands for best per formance, the larger Classic-8s are floor mounting. They have the same rounded styling and measure 225mm wide, 900mm high and 290mm deep. Both systems have overload protection, presumably by means of positive temperature coefficient (PTC) thermistors. The crossover frequencies for the Classic-8s are at 700Hz and 2.5kHz and its sensitivity is the same as the smaller model. Its impedance curve is shown in Fig.2 and again, it could be regarded as a 60 system. not have the reedy quality, probably a beneficial result of the 3-way crosso­ver network. As you would expect, the Classic-8s also have a consider­ ably more extended bass response, down to below 40Hz and this gives a lot of extra weight to orchestral, piano and organ music although it does not make all that much difference to most rock music. Overall though, we were most impressed with the Classic-4s. They give a very well-balanced sound with plenty of punch in the bass and good power handling. The much dearer Classic-8s have more extended bass and a less coloured midrange and more power handling capacity. Both speak­ers will serve very well and with their styling a plus, they are sure to be popular. Both are available in black or mahogany. The Classic-4s are $999 a pair and the Classic-Bs are $1899 a pair. Listening tests Our listening tests embraced a wide range of CDs, involving classical, jazz and rock music. Both gave a very satisfying performance. In more detail, the Classic-4 has quite a smooth re­sponse overall with bass well main­ tained down to below 60Hz. The tweeter tends to be a little prominent in the region of 5kHz to 6kHz and also had a tendency to be slightly "reedy" when sinewaves were being repro­duced. The Classic-8s use the same tweeter as the Classic-4s and it was similarly prominent in the midrange but did Where to buy them All the Classic range have dual recessed terminal panels with gold plated metal straps. Note the flarred bass reflex port to reduce "chaffing". Jamo Classic speakers are on sale at selected hifi retailers. For further in­formation, contact Scan Audio Pty Ltd, 52 Crown Street, Richmond, Vic 3121. Phone (03) 9429 2199. SC SC ANOTHER GREAT DEAL FROM MACSERVICE 100MHz Tektronix 465M Oscilloscope 2-Channel, Delayed Timebase VERTICAL SYSTEM Bandwidth & Rise Time: DC to 100MHz (-3dB) and 3.5ns or less for DC coupling and -15°C to +55°C. Bandwidth Limit Mode: Bandwidth limited to 20MHz. Deflection Factor: 5mV/div to 5V/div in 10 steps (1-2-5 sequence). DC accuracy: ±2% 0-40°C; ±3% -15-0°C, 40-55°C. Uncalibrated, continuously variable between settings, and to at least 12.5V/div. Common-Mode Rejection Ratio: 25:1 to 10MHz; 10:1 from 10-50MHz, 6cm sinewave. (ADD Mode with Ch 2 inverted.) Display Modes: Ch 1, Ch 2 (normal or inverted), alternate, chopped (250kHz rate), added, X-Y. Input R and C: 1MΩ ±2%; approx 20pF. Max Input Voltage: DC or AC coupled ±250VDC + peak AC at 50kHz, derated above 50KHz. HORIZONTAL DEFLECTION Timebase A: 0.5s/div to 0.05µs/div in 22 steps (1-2-5 sequence). X10 mag extends fastest sweep rate to 5ns/div. Timebase B: 50ms/div to 0.05µs/div in 19 steps (1-2-5 sequence). X10 mag extends maximum sweep rate to 5ns/div. Horizontal Display Modes: A, A Intensified by B, B delayed by A, and mixed. CALIBRATED SWEEP DELAY Calibrated Delay Time: Continuous from 0.1µs to at least 5s after the start of the delaying A sweep. Differential Time Measurement Accuracy: for measurements $900 of two or more major dial divisions: +15°C to +35°C 1% + 0.1% of full scale; 0°C to +55°C additional 1% allowed. TRIGGERING A & B A Trigger Modes: Normal Sweep is triggered by an internal vertical amplifier signal, external signal, or internal power line signal. A bright baseline is provided only in presence of trigger signal. Automatic: a bright baseline is displayed in the absence of input signals. Triggering is the same as normal-mode above 40Hz. Single (main time base only). The sweep occurs once with the same triggering as normal. The capability to re-arm the sweep and illuminate the reset lamp is provided. The sweep activates when the next trigger is applied for rearming. A Trigger Holdoff: Increases A sweep holdoff time to at least 10X the TIME/DIV settings, except at 0.2s and 0.5s. Trigger View: View external and internal trigger signals; Ext X1, 100mV/div, Ext -: 10, 1V/div. Level and Slope: Internal, permits triggering at any point on the positive or negative slopes of the displayed waveform. External, permits continuously variable triggering on any level between +1.0V and -1.0V on either slope of the trigger signal. A Sources: Ch 1, Ch 2, NORM (all display modes triggered by the combined waveforms from Ch 1 and 2), LINE, EXT, EXT :-10. B Sources: B starts after delay time; Ch 1, Ch 2, NORM, EXT, EXT :-10. Optional cover for CRT screen – $35 through the vertical system. Continuously variable between steps and to at least 12.5V/div. X Axis Bandwidth: DC to at least 4MHz; Y Axis Bandwidth: DC to 100MHz; X-Y Phase: Less than 3° from DC to 50kHz. DISPLAY CRT: 5-inch, rectangular tube; 8 x 10cm display; P31 phosphor. Graticule: Internal, non-parallax; illuminated. 8 x 10cm markings with horizontal and vertical centerlines further marked in 0.2cm increments. 10% and 90% for rise time measurements. Australia’s Largest Remarketer of markings Graticule Illumination: variable. Beam Test & Measurement Equipment Finder: Limits the display to within the graticule area and provides a visible 9500; Fax: (03) 9562 9590 display when pushed. X-Y OPERATION Sensitivity: 5mV/div to 5V/div in 10 steps (1-2-5 sequence) MACSERVICE PTY LTD 20 Fulton Street, Oakleigh Sth, Vic., 3167. Tel: (03) 9562 **Illustrations are representative only. Products listed are refurbished unless otherwise stated. July 1995  11