Scan-Speak 15W/8530K00 + D2905/9700

It was my intention to call this a mini-monitor, but after having set up the system, I realised this was anything but a mini. Small in size, yes, but in sound it's rivalling many 6"+1" floorstanders.

This construction came about due to a guy in Sweden having a pair of Opera Callas cabinets fitted with some OEM drivers. The new Callas use the Scan-Speak 15W/8530-K00 and - presumeambly - the 9500 tweeter. Here the 9700 tweeter is used.

I like the cabinet design and decided to set up the drivers in my test cabs to see what could be done and I will probably make some nice looking mahogany cabs like these some day. Until further the drivers will stay in my test cabs due to other projects. But the crossover design is finished and shown below.

Basics

The ScanSpeak range of coated midbass drivers includes the 15W/8530-K00 and the 15W/8530-K01, the latter with a smaller magnet compared to the -K00. These drivers have - to my knowledge - an unsurpassed bass capability and an unusual upper frequency extension only declining around 8-10 kHz. Almost full-range drivers. However, given the high quality of bass and midrange, I don't think anyone would even consider using them as full-range drivers. Below the FR of the 15W/8530K00 driver and the D2905/9700 tweeter without crossover. (FR = frequency response).

Red = 15W, blue = 9700. As can be seen, these drivers provide a major overlap and placing the drivers on a 19 x 300 mm baffle leaves some baffle step compensation for the W15 drivers to be done and the 9700 having a dip at 3.5 kHz and bump at 2 kHz will take some equalisation to get it right. Placing the drivers in a 2pi environment produces a much better FR profile but this is mini and small it must be.

The Crossover
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Series crossover for the W1500/97 - please note that series filters cannot be bi-wired!

Crossover Kit
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Complete crossover kit excl. drivers available from Jantzen Audio: contact@jantzen-audio.com
Superior Z-caps also available.

The cabs
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Left: Box simulation based on SS data.Right: FR in-room from placing the speaker on a stand with the bass driver 80 cm above floor level, 110 cm from rear wall and 180 cm to side walls.

Cabinet drawing. Cabinets made from 19 mm MDF.

Also make sure the tweeter is placed at the centre line of the front panel.
The crossover is optimised for this position.

Measurements
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Due to the large magnet and small baffle size, the W15 needs some equalisation in the midrange.
Shown here is the effect of the midrange notch filter. Very necessary indeed. I have tried making a double notch filter for the midrange bump due to width of the bump and this did produce a nicer FR profile but the sonic benefits from this were negligible. Thus the single notch filter still producing a nice FR of +/- 1.5 dB in the upper midrange.

FR of individual drivers and summed response. Point of crossover is close to 3 kHz.
The drivers mounted on the centre line of a 190 x 300 mm front panel.