Cardinal-TBFC-DCR (the Final Cut)

Cardinal-TBFC-DCR
40L Dual Chamber Reflex

In the previous version, the Cardinal-TBFC, I wasn’t too happy with the bass. The midrange and treble are not an issue but the bass sounds constipated in a 15 liters box.

I went through my box modelling and found that the 830874 simulated well in a 40 liters Dual Chamber Reflex (DCR). I was hoping that the DCR will increase the volume of the bass. I gave it a shot and what do you know, it came out better than I had expected.

Fig 1 – Peerless 830874 RAW response in 40 L DCR

Fig 1 is the RAW response of the 830874 in a DCR with a Baffle Width of 9″. Disregard the deep notch at 150Hz. That’s caused by a floor bounce in my setup.

As usual, the 830874 has a beautiful, flat midrange. The effects of the baffle step is clearly seen as a rising response at 400Hz. What is most important is the midrange is now only about 2dB more than the bass whereas in the 15 liters bass reflex that I used in the Cardinal-TBFC, there was a 7dB difference.

Fig 2 – Peerless 830874 with Low Pass Filter (LPF)

Instead of using the response as is, I decided to lower the midrange to that of the bass. I don’t want the midrange to be too prominent. The Blue plot in Fig 2 is the 830874 with a new Low Pass Network. The midrange is now lowered by about 3dB.

Fig 3 – 830874 Low Pass with 27TBFC High Pass

The Red plot in Fig 3 is the Seas 27TBFC with a High Pass network adjusted for the new response of the woofer. I am still maintaining the same crossover frequency as before.

Fig 4 – Cardinal-TBFC-DCR Passband

The Black plot in Fig 4 is the summation of the 830874 with the 27TBFC. No cancellations are observed in the passband which is an indication of good summing.

Fig 5 – Cardinal-TBFC-DCR Frequency Response

The final frequency response of the Cardinal-TBFC-DCR is in Fig 5. The midrange is now almost level with the bass, maybe 1dB more at 2kHz. This is not an issue for me because I prefer the midrange to have a little bit more emphasis. If it is too much, I can lower it after auditioning.

Fig 6 – Cardinal-TBFC-DCR Null

The Violet plot in Fig 6 is the Null when I flipped the tweeter’s wires around. The center is about 1.7kHz, which is close to my crossover frequency. The notch is fairly deep, indicating the phase alignment of the two drivers is quite close.

Sound of Cardinal-TBFC-DCR

The loudness of the bass has improved tremendously compared to the 15 liters bass reflex version. The bass goes deeper and doesn’t sound constipated.

Initially, I was rather disappointed that the bass sounded quite ordinary. There’s no life in it. Dull. Then, I decided to increase the volume and my gosh, the bass came alive. It’s like a completely different speaker. It’s dynamic, punches and fast. I don’t think I’ve ever come across a woofer like this before. Apparently the 830874 needs some power to show what’s she capable of.

This DCR version is far better than the bass reflex. I am more than satisfied at how this Cardinal-TBFC-DCR turned out. If you like your music on the loud side, you’ll love this DCR. Seriously, I never expected the 830874 to punch like this.

Crossover is available on request. Free for DIY. Not for Commercial use.
Unless otherwise stated, all measurements were made with the mic at 36 ins, tweeter axis. Impulse Window=5ms. No smoothing applied.