Vendor guidelines - Scan-Speak:

1. R2904/700000 1" ring radiator tweeter. This is Scan-Speak's latest entry into the rarified supertweeter field, visually impressive with its long, needle-like phase plug. Although nominally 1" (25 mm) in diameter, the radiating area of this unit's ring radiator is more similar to that of a 3/4" (19 mm) unit. Also, as seen clearly in the FR graph, this unit should never be crossed over too low. In this sense, this is the high-end equivalent of the Vifa XT25. All reports so far indicate that in a good design, its performance is superb.  view   response 

   Note:	The R2904/7000, along with the AccutonC223/6, Hiquphon OW I/II/III, Human 002, Morel MDM33, and the Alison Acoustics 4010203 (available only as a replacement part for Allison loudspeakers) are considered by many to be the ultimate electrodynamic tweeters.

2. D2905/9900 "Revelator" 1" soft dome tweeter. This is Scan-Speak's self- described ultimate tweeter. Unusual design features include a slightly concave mounting plate to provide quasi-horn loading, and eschewing the usual use of ferrofluid in order to provide better response. Some of my respondents said that the Revelator is too "bright" or "edgy" for their tastes. These same respondents tended to be those who say the same things about metal dome tweeters, although their comments on the Revelator were significantly less extreme than about the Dynaudio tweeters.  view   response 
3. D2905/9700 1" soft dome tweeter. This is the Revelator without the concave face plate. At least one of my respondents who didn't like the Revelator said he could tolerate this variant.  view   response 
4. D2905/9300 1" soft dome tweeter. This is the last pre-Revelator tweeter. It features a flat face plate and uses ferrofluid. Everyone seems to like this tweeter, even those who prefer the Revelator.  view   response 
5. D2905/9500 1" soft dome tweeter. This uses the improved Revelator motor and back chamber while retaining the ferrofluid and flat face plate. This is the one Scan-Speak tweeter that everyone who's heard it seems to agree rates as excellent, regardless of their opinions on the Revelator.  view   response 
6. D2904/6000 1" soft dome tweeter. Quite simply, the 6000 is for people wanting the characteristics of a Scan-Speak soft dome design with a small diameter face plate. It features a self-shielding neodymium version of Scan-Speak's excellent Symmetric Drive^TM motor.  view   response 
7. D2904/9800 1" metal dome tweeter. Quite simply, the 9800 is for people wanting Scan-Speak quality in a metal dome. It features a flat face plate and has a small phase control device similar to Focal's metal domes. It also has some nasty breakup modes at 30-40 kHz which, although outside the range of human hearing, should be tamed in the crossover to avoid audible artifacts (i.e. "metal sound").  view   response 
8. 13M/8636 shallow cone/dome midrange. Similar to the less expensive paper-coned 8640 (no longer recommended), the 8636 features a Kevlar cone. Although a midrange, Fs is only 59 Hz. The 8636 features usable response from a few hundred Hz out past 13 kHz. with notably low distortion in the passband. One of my respondents noted, "The SS 13M 8636 , although a bit long of tooth, is usable in a 1st order/multislope design; it is quite musical."  view   response 
9. 15W/8530K00 5" mid/bass. This is the first mid/bass driver of this size from Scan-Speak. It uses a unique slitted-paper cone (see Section 1 for details) which provides excellent transient response, low coloration, and minimal resonance effects. It does, however, have a broad FR plateau above 1 kHz which must be compensated in the crossover. What's especially noteworthy about this driver is its extreme Xmax (6.5 mm!) for a 5.25" driver. This driver is optimized for vented enclosures.  view   response 

10. 15W/8530K01 5" mid/bass. This is identical to the 15W/8530K00 in most respects, although a higher-Q driver intended for use in sealed enclosures. All other comments apply.  view   response 

11. 18W/8545K 7" mid/bass. This unusual driver uses a paper cone coated with a rough slurry of carbon fiber reinforcing, giving the appearance of papier mache. Both use their advanced SD-1 motor. The difference between them is that the 8545K has a Kapton former (hence the "K"), while the 8545 uses an aluminum former. Using a Kapton former increases the Qms of a driver. (8545K Qms = 5.2, 8545 Qms = 2.3) Both will require almost identical enclosures. But because of the higher Qms you will notice a slightly sharper roll-off and a slightly more pronounced bass at around 50 Hz. Many who have them both prefer the 8545 for 2-way applications, and the 8545K for woofer applications.  view   response 
12. 18W/8546 mid/bass. This 7" Kevlar-coned unit is a technical tour de force which proves that Kevlar can be controlled. Otherwise similar to the 8545 models, the 8546 features significantly lower Mms and a correspondingly tighter sound.  view   response 
13. 21W/8554-00 woofer. This unit features an 8" Kevlar cone and is optimized as a small woofer, using a special long-throw version of the SD-1 motor. Note that the Kevlar cone begins breaking up over 1 kHz or so, so this driver should ideally be crossed over below that. Operating within that limitation, it easily ranks as one of the best 8" woofers available. Read more detail about how it compares to some other popular drivers at the Linkwitz Lab web site.  view   response 
14. 25W/8565-01 woofer (called a subwoofer in Scan-Speak literature). This unit features a carbon fiber reinforced 10" paper cone and is optimized as a small subwoofer, using a special version of the SD-1 motor. Vance Dickason has reported favorably on this unit in Speaker Builder. One of my respondents notes that it can be used successfully in a 6.5 cu.ft. (184 l.) box with an in-room F3 of 20 Hz.  view   response