Vendor guidelines - Peerless:

Peerless is a sister company to Scan-Speak and Vifa, all owned by Danish Sound Technology [now Tymphany]. Although Peerless makes a competent full line of drivers, it is best known for its woofers, subwoofers, and mid/bass drivers. The standard and CC lines feature PP cones, while the CSC and CSC-X (CSX) lines feature proprietary composite sandwich cones. The CSX line adds an advanced magnet structure with a shorting ring to improve linearity. Peerless has also recently introduced a new HDS line of cast frame, high-displacement drivers using CSX motor and cone technology.

Based on my respondents, all of Peerless' woofers, subwoofers, and mid/bass units - and especially the CSC and CSX lines - can be recommended. All you need to do is to check the curves and numbers to determine which units will work best in your planned project. Some drivers worthy of special consideration include:

1. The 830500 12" XLS woofer. The "XLS" designates a new series of extremely long stroke woofers. Featuring an extremely wide and compliant surround, NomexTM cone, and an excellent motor, these have been recommended by several people. With a quite low Qts value (0.20), it's only suited for use in small vented or PR enclosures. Most who've used it have had success using its matching 830548 12", 425 gram PR (see below for more PR information) in a 40  liter (1.41 cu.ft.) box. This yields an alignment with F3=45 Hz and F10=20 Hz.

2. The 831857 12" subwoofer. Part of the CC line, this unit offers one of the most attractive balances between price and performance in the crowded 12" subwoofer market. It's especially attractive for those who might shy away from the Swan 305 (see below) due to the latter's use of a foam surround. Used in a 6.5 cu.ft. vented enclosure, this driver can put out 15 dB more acoustic energy at 20 Hz than an NHT 1259 (see also) in a 3.3 cu.ft. sealed enclosure.

3. The 830452 10" XLS woofer. With a very low Qts value (0.17), it's only suited for use in small vented or PR enclosures. Most who've used it have had success using its matching 830481 10", 400 gram PR in a 35  liter (1.24 cu.ft.) box. This yields an EBS alignment (see discussion of enclosure types IDSG) with F3=78 Hz, but which is only 7 dB down at 20 Hz.

4. The 850146 10" CSX woofer. Usable in sealed or vented enclosures, this unit combines great FR with some exceptional numbers (Xmax = 9 mm., Fs = 22 Hz) for an affordable 10" woofer.

5. The 850136 8" CSX woofer. Even flatter FR than the 850146. There aren't as many good 8" woofers as there used to be - this is one of them. Obviously, not as much bass, but an even better bargain.

6. The 850490 8" HDS woofer. Even smoother FR than the 850136. With its "aerodynamic" cast frame and advanced sandwich cone, this is the next step up - in both sonic quality and cost - from the 850136.

7. The 850118 7" CSC woofer - actually a mid/bass driver. This unit features flat FR within 1 dB from 70 Hz out to 2 kHz. It's also a best buy in the crowded 7" mid/bass field.

8. The 850439 6.5" HDS mid/bass looks to be a major new star in the crowded 6.5" mid/bass market. One of these has already found its way into one DIY system, mated with a Hiquphon OWI, and described as "a [Scan-Speak] killer".

9. The 850122 6.5" CSX mid/bass. There's a lot of competition in mid/bass drivers from 5.5" to 7" diameter. The 850122 offer exceptional FR curves, good numbers, and an affordable price.

10. The 850108 5.5" CSX woofer - actually a mid/bass driver. This affordable unit is flat within 2 dB from 100 Hz to beyond 3 kHz. Roll offs at either end are smooth and well-behaved. Predecessor to the 850488 driver (see below), the 850108 offers a lower Fs value, albeit with lower Xmax as well.

11. The 850488 5.5" HDS mid/bass follows the considerable success of its pre-HDS predecessor, the 850108 - all at an even lower cost! Roll offs at either end are even smoother and well-behaved than the 850108. This unit competes head-to-head with the equally outstanding and highly regarded Vifa P13WH-00-08 for midrange applications. All 85108 comments apply.

12. The 821615 4.5" midrange features a PP cone and an integral housing, eliminating the need for a separate midrange enclosure. On-axis response is ruler-flat from just above its 530 Hz Fs out to 5 kHz. Off-axis response isn't as good, but still looks usable out to about 3 kHz.

13. The 811815 1" tweeter features a soft fabric dome and a controlled directivity faceplate (i.e. a shallow horn). On-axis response is quite flat from 2 kHz all the out to 20 kHz, albeit with a broad, shallow (~1.5 dB) dip in the 5-10 kHz range. Off-axis response is very good out to about 10 kHz. This is the same tweeter used in the well-reviewed Meadowlark Kestral system.

14. The 811830 1" tweeter is virtually identical to the 811815 in most respects. The difference (other than a $1 higher price) is that the 811830 uses ferrofluid and has a coil/motor assembly specially deisgned for higher power and lower power compression. Most 811815 comments also apply to the 811830, except that the 811830 has a higher value of Fs - apparently the price of the higher power handling.

Passive radiators:

Passive radiators (PR's), are also known as auxiliary bass radiators (ABR's) and "drone cones". Simply stated these are woofer/subwoofer chassis with cones but no motor. The only characteristics of PR's are their excursion limit, compliance, and their resonant frequency (determined mostly by cone mass). PR systems use one or more woofers in a sealed box with a PR. Since the box is sealed and the PR has no magnetic motor, the PR's motion is entirely determined by the air in the enclosure and the back wave of the woofer(s). System design and modeling are exactly as for a ported system, except the port tuning is replaced by adjusting the PR's mass to match the mass of the air in an equivalent vent with the same cross-sectional area as the Sd of the PR. For best results, the PR should therefore have low mass, a compliant suspension capable of wide excursions, and a resonant frequency below both the box and port tuning frequencies.

Any DIY'er can make a PR from an old woofer by simply removing the magnet and voice coil assembly, leaving only the chassis and cone. This is generally not a good idea. The PR's "Xmax" will be equal to Xsus of the driver. Without the constraints of motor design, PR designers can achieve outrageously high vales of Xsus. As might be expected, along with the PR's typically compliant suspension, this raises Vas considerably. Furthermore, good PR's typically use much more massive cones than drivers, resulting in a subsonic Fs and a very high Qms. For more professional (and cosmetically pleasing) results, there are several commercial sources of PR's listed below. The currently preeminent source for general purpose PR's is Stryke Audio. There are several vendors who produce PR's specially designed to work one or more of their own drivers.

For more information on PR's in general, read "Passive Radiator Enclosures: In Theory and In Practice" by Adam Bird.

PR Details: