Vendor guidelines - Seas:

Seas has a typically cryptic, yet meaningful parts numbering system. Atypically, they also have a simplified parts numbering system as well. Although the long are used in the LDSG, it's often easier to order them with the short number. For this reason, the short numbers are stated below in parentheses Based on feedback, here are some units worth considering:

1. The Excel T25CF001 (E006) 1" soft dome tweeter. This unit features a number of advanced design features (silver VC wire, double magnet structure, special rear chambering) along with generally excellent curves and numbers. For a top-of-the-line unit, it's also amazingly inexpensive (compare the price to some of the top Dynaudio or Scan-Speak units!) One typical comment was, "…it [sounds] 'extended'. In other words, I think it's doing things right in the top octave. It's not quite as harmonically rich as the [Scan-Speak series] D2905, nor quite as transparent as the [Dynaudio] D-260 [but] it's worth its price.  view   response   waterfall 


2. The Excel T25C003 (E0036) 1" soft dome tweeter. This is essentially the T25CF001 (see above), but without ferrofluid cooling and with 2 dB higher sensitivity. All other comments apply.  view   response   waterfall 


3. The Excel T25CF002 (E011) 1" soft dome tweeter with "Hexadym" magnet system. Called the "Millennium" tweeter, this unit improves on the already excellent E006 unit. Using a new patented "Hexadym" neodymium magnet system, this unit features even lower Fs than the first Excel tweeter. This improvement comes at a price. Though still not as expensive as many competing high-end tweeters, it's not a clear value leader like the E006. In particular,it actually costs more than the excellent Scan-Speak D2905/9500 and 9900 Revelator, Accuton C2-12, Morel MDT33, and Dynaudio Esotec units. Also, like the E006, the motor features inherently low flux leakage (since the E011 isn't quite as good in this regard as the E006, it's not listed in the comparison tables as a shielded driver).  view   response   waterfall 


4. The Excel W15CY-001 (E0015) 5.5" mid/bass. Recently introduced, this supercedes the W14CY-001. This has been recommended as arguably the best midrange or mid/bass of its size. Like all magnesium cones, you have to deal with breakup in the crossover, but in this unit, the breakup comes at 9 kHz.  response & impedance   distortion 


5. The Excel M15CH001 (E0016) 5" midrange. This unit continues the excellent line of Seas midrange drivers into the Excel line. In many ways similar to the outstanding MP14RCY/P (also, see below), this driver also features a polypropylene cone. Unlike the MP14RCY/P, this driver also features the latest Seas Hexadym motor and a solid copper phase plug. The advanced motor design features dual copper Faraday rings. What's important isn't the technology but the results. According to those who've heard this driver, it sounds great and has the added virtue of being easy to work with.  view   response & impedance   distortion 


6. The Excel W18E-001 (E0018) and W18EX-001 (E0017) 6.5" magnesium cone mid/bass's are recommended for experts only. Recently introduced, these supercede the W17E-002 and W17EX-002. They have great numbers and exceptionally low passband distortion as well as pretty good curves in the passband. They also have a really nasty primary resonance at 5 kHz along with a smaller secondary resonance at 1.8 kHz, both of which must be properly filtered. If you want the desirable qualities of a metal cone without the hassle of the Seas units, try one of E.J. Jordan's 5" or 6" drivers.  response & impedance   distortion   response & impedance   distortion 


7. The Excel W21EX-001 (E004) 8" woofer with phase plug. This is an excellent choice for someone wanting the advanced technology of the Seas Excel motors, yet who doesn't want to deal with the crossover design headaches of on of the magnesium cone drivers. Using a "specially treated hard paper" cone, the upper end of this driver is as well-behaved as the magnesium-coned units are problematic. The cost is, not unexpectedly, higher distrotion figures than the rigid magnesium cones.  view   response 


8. The Excel W26FX0001 (E0026) 10" aluminum/magnesium alloy cone woofer is Seas' first entry into the large high-excursion woofer market. By all accounts, it's excellent! The typical metal cone breakup doesn't start until around 4 kHz, well above its normal operating range.  view   response   distortion 


9. The 19TFF1 (H737) 3/4" soft dome tweeter. This is an excellent supertweeter, but don't cross it over below 3 kHz, minimum.  response   waterfall 


10. The 19TAF/D (H561) 3/4" aluminum dome tweeter. Similar in many respects (except, obviously, for the dome material) to the 19TFF, this unit features a diffuser which enhances dispersion above 10-15 kHz.  view   response   waterfall 


11. The 25TAC/D (H535) aluminum dome tweeter. Well reported, this unit features a chambered back for extended low end response, and a diffuser to provide off-axis response which closely matches the on-axis response. A best buy in the crowded 1" metal dome class.  view   response 


12. The 25TFFC (H519) fabric dome tweeter. The fabric dome equivalent to the 25TAC/D, the 25TFFC lacks the diffuser of the aluminum dome and has a higher FS. On the other hand, its waterfall plot is excellent. This is another Seas best buy.  response 


13. The 27TFFC (H881) fabric dome tweeter. Although fairly new, this economical unit has been recommended by several people. Although Fs is higher than the 25TAC/D, it has been used successfully in 2-way designs crossing over around 2 kHz. Compared to the 25TFFC, the similar 27TFF features greater power handling and flatter response in the passband, at the cost of a somewhat inferior waterfall plot. This is another Seas best buy.  response   waterfall 


14. The 27TDFC (H1189) fabric dome tweeter. Conditionally recommended. This is one of Seas' newest drivers, so I haven't had a lot of feedback on it so far. Early indications are that it's an excellent choice for a low-Fs fabric dome tweeter. According to Seas, it features better power handling than the 27TFFC. Also available shielded as the model 27TDFC/TV (H1210).  view   response   waterfall 


15. The 11F-GX (H149) 4.5" treated paper cone mid/bass. Useful primarily as a woofer in tiny satellite speakers, this driver has excellent linearity and smooth response out to 5 kHz.  view   response 


16. The MCA11FC (H143) 4.5" treated paper cone midrange. A remarkably flat and affordable cone midrange unit.  response 


17. The MP12VC (H453) 4.7" PP cone midrange. The lowest priced member of the triumpherate of Seas' excellent midrange drivers. Featuring the same flat response as the MCA11FC and MP14RCY/P, this low-Q unit is used in the critically praised NHT 3.3 speaker system.  view   response   waterfall 


18. The L12RCY/P (H1207) 4.5" aluminum cone midrange driver. Another in Seas great midrange lineup, this new driver features excellent Xmax for a 4.5" driver, combined with a phase plug and Seas latest standard line motor technology. The aluminum cone breakup occurs around 9 kHz, facilitating taming it in the crossover.  view   response 


19. The MP14RCY/P (H522) 5" PP cone midrange. This unit features exceptionally flat response. It's also notable for a low Fs value (compared to other 5" drivers) of 43 Hz, but the Q is so low that it's really unusable as a mid/bass driver.  response 


20. The L15RLY/P (H1141) 5" aluminum cone midrange driver. Another in Seas great midrange lineup, this new driver features excellent Xmax for a 5" driver, combined with a phase plug and Seas latest standard line motor technology. Response is quite flat except for a slight hump at 200 Hz, which can actually be used to help with baffle step correction. The aluminum cone breakup begins around 5 kHz, with the strongest resonance around 9 kHz, facilitating taming it in the crossover.  view   response 


21. The L17RCY/P (H763) 6.5" aluminum cone mid/bass driver. An affordable driver to experiment with metal cones. Used in a 2-way system, cross it over as low as possible with a minimum 3rd order electrical filter. If you can use this successfully, you may be ready to move on to the Excel magnesium cone drivers (see below).  response 


22. The P17REX (H416) 6.5" PP cone mid/bass driver. This has become one of Seas' most popular drivers, judging by the recommendations I've received. This unit uses an advanced motor to linearize the system. Its cone is also reported to have higher stiffness than other PP cones, though the reason isn't clear.  view   response 


23. The T17RE (H823) 6.5" PP/TPX cone mid/bass driver. Seas makes a number of 6.5" mid/ bass drivers. The variables include: 1) designed for sealed, ported, or both; 2) cone material, paper, metal, PP, or PP/TPX; 3) phase plug or no phase plug; and 4) shielded or unshielded. Most of these have been recommended at some time, but probably best all-around is the recently introduced T17RE, one of Seas' first drivers to use its new PP/TPX cone material. Once the FR anomalies are accounted for, the response is quite decent, with well-controlled roll-offs at each end.  response 


24. The L21RNX/P (H955) 8" aluminum cone woofer. Although this is subject to the typical metal cone breakup and resonance artifacts (around 5 kHz, in the case of this driver), it's use as a woofer can be recommended with a suitably low crossover point.  response 


25. The L21RN4X/P (H956) 8" aluminum cone woofer. Similar to the L21RNX/P above, the L21RN4X/P is a lower Q, larger Xmax, slightly higher compliance version suitable for smaller boxes.  response 


26. The L26RFX/P (H1209) 10" aluminum cone woofer. Continuing Seas' movement into larger cone sizes, this is another new driver featuring all of Seas' latest standard line technology. Featuring decent Xmax, this driver's strength is its extended, flat response up to 1 kHz. The expected aluminum cone breakup is held off until about 5 kHz, making it easy to tame in the crossover.  response