"Sliced Paper" SP95
Copyright 2009 © Troels Gravesen

ScanSpeak 18W/8531G00 + ScanSpeak D2905/9500

Actually this is a 9700 tweeter. The copper plating of the pole piece is seen through the dome.
But it's supposed to be the 9500. Sorry.

The 18W/8531 driver has long been on my wish list. Everything about this driver looks good. The TS data suggest impressive bass performance and the response curves do not appear to have any serious break-ups as seen from so many other drivers. A slightly elevated SPL response from 1 - 8 (!) kHz should be easy to control in the crossover. Has Scan-Speak really been able to make a non-coated paper cone with these properties

Indeed the 18W/8531G00 is a remarkable driver. At this point in time it is being tested in a 33 litre cabinet with a port tuning of 33 Hz, vent = 60 x 140 mm (ID x L) placed 30 cm above floor level including base support, and the bass from this set-up by far supersedes the bass from the 2.5 clone 18W/8535-00 driver in terms of depth and low-end resolution. I have never experienced such a rich and articulate bass from a single 6½" driver. In addition to this, the 8531 has the low-midrange weight and warmth the 8535 is short of.

Series and parallel crossovers have been constructed to gain similar frequency response and to compare the performance of the two speakers. The sonic impact of the two filters on the resulting sound has been very confusing. Despite very close response profiles, the sound is very much different. The series filter has an immediate appealing sound with lots of see-through capability where the parallel filter gave rather confusing results. The sound from the parallel filter appears flat and everything seems to happen in front panel plane.

Cabinet construction

Driver placement

Test cabinets, 33 liter vented, port tuning = 33 Hz.

Chamfering of the bass driver hole to provide proper ventilation.

Cabinet bracing and bitumen pads on internal walls.
Bottom panel lifted 4 cm allowing crossover to be placed here.
Tweeter has it's own chamber.

The Crossover

SP95s, series filter, version 4.

Complete crossover kit available at Jantzen Audio: contact@jantzen-audio.com

Measurements

Initially I have run the crossover without a midrange notch filter. However, it is apparent that the midrange, 500-1500 Hz, is a couple of dBs too loud. So I added a mild midrange notchfilter to smooth the performance.

Left: SP95, SPL response, red = V4 series filter. Blue = parallel filter (crossover not shown). Readings not normalised for 2.8 volts/1 meter.
System sensitivity = 86 dB/2.8 volts/1 meter.
Right: Impact on midbass response from midrange LCR notch filter.

The red graph is without the notch filter. This doesn't look too serious and this driver has a midrange quality that actually makes you consider leaving it there. But the sound is very much right in your face and it's too much in the long run. It's just not natural despite the gain in see-through capability. Without the notch filter you can hear every faint cough from a live audience. The addition of the notch filter can certainly be heard and it adds to the naturalness of voices and instruments. The current set-up targets the BBC-dip and the apparent drop in tweeter level is in no way felt the way it looks.

Having a pair of 2.5 clone identical cabs I reinstalled the 2.95 set-up. Quite interesting and exiting to hear it again. These speakers sound quite different and I have some trouble describing the sound. I have gone through a number of vocal recordings and two things become apparent: The 8531 (still series filter) has some presence effect, where the 2.95 has a more lean and distant sound, actually a tonal balance that I think is quite good. BUT, the 8531 has warmth in the lower midrange and upper bass that makes the 2.95 sound "smaller" and "thinner". The 2.95 sound somewhat "cool" - in the sense of cold. The differences in vocal presentation are tricky. Swapping back and forth it becomes apparent that the harshness to vocals singing loud is clearly reduced from the 8531 driver. It's doesn't have that sometimes ear-shredding type of distortion as heard from the 8535.

Impedance and phase of SP95 from series and parallel filters.
Red/blue = parallel filter. Green/yellow = series filter.

Sonic performance, SP95s-V4.

I'm afraid this is where it's going to end for the time being. "Afraid"? Well, I'm not really sure this 8531 driver was meant to perform in a two-way system up to 2.5 kHz. Rather in a three-way system. A classical set-up would be the 8531 + the new 12M sliced paper driver from SS with a point of crossover at some 800 Hz -or a rather more modern three-way system with the 15M for midrange taking over at 300-400 Hz. The sound from this series-V4 is very transparent and with good tonal balance but I still think the 8531 has a certain "paper-sound". Too much lushness, if you get my meaning. Almost a classical JBL sound despite having a rather flat response contrary to the old JBL speakers (I'm thinking of the L100).

I feel very tempted to coat the 8531 driver, but applying coating material to a 300 US$ driver is a one-way ticket and you may end up ruining the driver. I'll have to consider this carefully. I'm sure some people will say that this is just what they want, and others will notice the "sound" (= colouration) from this 8531 driver giving too much sparkle to a piano note or a vocal performance. Running the SP95s-V4 from a Copland CTA505 valve power amplifier in triode mode and a home-made valve pre-amplifier makes this coloration less pronounced, so be sure not to have some aggressive front-end driving this speaker.

Comments on SP95p and SP95s-v4 from Darryl, Australia:

1. Here are my initial impressions of the SP95 series v4.
I haven't had a great deal of listening time, so I'll be brief: These are A-B mono comparisons:
Where the parallel sounds forward and flat, the series is comparatively laid back and there is more than a hint of layering, even in single-speaker mono. The parallel sounds hard and arid, while the series is more rounded - not overly so, just closer to reality. Vocals are more natural as a result, as are instruments such as violin and piano. I haven't listened to any spoken voice yet, so just how natural vocals are I can't say. (I'd say they're definitely less coloured, but this is still a distinctive speaker in the upper midrange.)
Some excitement is lost with the series, but in absolute terms this is still an exciting speaker. In any case, what use is being hit between the eyes if fatigue sets in after only a short period of time? I found myself listening to the music with the series rather than to the speaker itself. I can't say that for the parallel. Overall, I think the SP95s is quite an improvement. More later.

2. Second series crossover now in place and listening in stereo.
Damn! These are great rock speakers and would suit any head-banger who wasn't too concerned about vocal accuracy. I've just been playing Keith Richards' "Main Offender" - loud, very loud! The SP95s had no problem coping with it at all. The bass was amazing and the illusion of a rock combo playing their hearts out was very believable. Vocals were coloured, but in this case the colouration probably suited Keith's somewhat thin voice. A JBL sound? Yes, but also reminiscent of those early Linn speakers where tonal accuracy took second place to pace and rhythm. These speakers move. At the moment I'm watching TV with the sound playing through the SP95s - British crime drama, one of the "Touch of Frost" movies. Sound from these movies is generally pretty good, and the SP95s seem more than capable of reproducing it. Vocals do have that "shhhh" colouration (reminds me of some movie theatre sound systems actually), but aside from that the SP95 does very well as an AV speaker. The rustle of clothing, the slam of a car door, footsteps . . . all very realistic. The 2.5/2.95 always disappointed here, probably because it lacked energy in the lower midrange.
There's a big difference in depth between the series and the parallel versions, but it wouldn't be difficult to better the parallel here - it didn't have any depth! (Still not the widest of sound stages though.) However, there's no doubt the series version is an improvement over the parallel. Vocals are still far from natural, but they are significantly better and I would no longer complain about "hoarseness" and "croakiness". Just before changing the second speaker, I compared the two with a number of piano recordings and the parallel sounded "clangy" - not so with the series. Violins, acoustic guitar and wind instruments also show significant improvement - rather sterile with the parallel.
In short, this is still a coloured speaker but no longer a fatiguing one - at least in the short term. Best suited to rock though.

Go to SP98-09 version