September 8, 2011

B&C 8PS21 pro high sensitivity 8" midwoofer

The B&C 8PS21 is a high sensitivity pro 8" midwoofer. This driver is used by Earl Geddes in his smallest speaker kit, the Harper and it represents very good value. It was measured by John K (Zaph Audio) and compared to some other 8" midwoofers. The distortion performance is comparable to a Scan Speak woofer at 3.5 times the price.

 For a pro midwoofer, it's not bad looking! I like the inverted dust cap and it has a cast frame and a more attractive mounting plate than most pro woofers.

It has a high fs that limits it's bottom end to about 80 Hz in a vented box - this is the price paid for sensitivity. It is around 94 dB 1W1m and has a decent 5mm xmax.

As you can see, the response is quite smooth. Measured nearfield bafflestep compensation but no high or low pass filters. I would say it could work up to about 2k with a fairly steep filter so it does require a tweeter that can handle a low crossover point. Here the value of a compression driver is seen, allowing flexibility in choosing the crossover point. The crossover can be chosen based on getting a polar match, anywhere from 1.5 - 2k.

My initial listening sessions with this in the system is that I like the sound of this driver. It's very clean and neutral and punches well above its price point when compared to hifi drivers. The clarity is immediately apparent.


  • High sensitivity
  • Decent xmax
  • Suited to small boxes
  • Well designed driver
  • Value


  • Fit and finish could be better
  • Requires a vent to get down low enough to mate to a subwoofer
  • Top end limited to 2k
  • Octagonal faceplate is a pest to flush mount
The casting on the frame is a little rough in places. This means that when flush mounting, a few parts stick out and a tight neat fit won't happen. Some of the paint was also damaged in transit and it appears to be one area where corners were cut. I'm tempted to attack it with a metal file. 

1 comment:

  1. I have the 8NDL51 in a 0.4 cu ft box tuned to 72Hz. I like it a lot.


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