about the Cardinal-DCR-TA
The Cardinal-DCR-TA is a time-aligned Dual Chamber Reflex (DCR) that I’ve been working on for many years. My first attempt was with a Silver Flute W17RC. Unfortunately, it was a total disaster. I then followed it up in 2010 with the Merlin. In that version, I replaced the W17RC with a Dayton RS-180s. It did make a marked improvement in the mid-bass. However, I was still left unsatisfied. I didn’t believe the DCR have yet to reached her full potential.
After sitting in a corner for seven years, I tried another woofer. This time round, I used a Peerless 830874. And VOILA……. SUCCESS. It gave me the sound I was looking for. I could easily have stopped there. It was already a very good speaker but since I’m working on time alignment, I thought perhaps this DCR could do with some. And true enough, the drivers time aligned beautifully.
Now, that the drivers are time aligned, the Cardinal-DCR-TA sounds wonderful. Time aligning the woofer and the tweeter means the sibilance in the vocals is spot on. No horrid “sssh” caused by phasing issues. Whatever that’s in the recording will be faithfully reproduced.
The strength of a DCR lies in the mid-bass. The Cardinal-DCR-TA excel in this department. None of my 2-way bass reflex can beat this DCR in the mid-bass.
the Peerless 830874 RAW Frequency Response
Fig 1 – Mic at 1 meter, tweeter axis, 1/12th octave smoothing. Measurements below 500Hz are in Nearfield.
It is clear from the plot in Fig 1 that the mid-range climbed by +5dB due to baffle step. A network must be used to correct this anomaly otherwise the speaker will end up sounding too bright.
Correcting Baffle Step
Fig 2 – Blue plot with Low Pass Filter and Baffle Step corrected.
The Blue plot in Fig 2 is the Peerless 830874 response after adjusting for Baffle Step and suppression of cone breakup. Note the tip at 4kHz is down -20dB now.
Integrating the Seas 27TBFC tweeter
Fig 3 – Red plot is Seas 27TBFC aluminum diaphragm tweeter.
The Red plot in Fig 3 is of the Seas 27TBFC. Though the response is slightly wavy, it is nothing to worry about. It will look a lot better when I flush mount the 27TBFC. Right now, it just a prototype.
Time Aligned Frequency Response of the Cardinal-DCR-TA
Fig 4 – Summed Response of the Peerless 830874 and the Seas 27TBFC tweeter.
Fig 4 is the full response of the Cardinal-DCR-TA. The Seas 27TBFC integrated well with the Peerless 830874. The response is remarkably flat. No smoothing is applied from 500Hz upwards.
Nulled Response with the Seas 27TBFC wired in Reversed Phase
Fig 5 – Summed Response with the Seas 27TBFC wired in Reversed Phase.
Fig 5 shows the response with the Seas 27TBFC wired in Reversed Phase. A deep and sharp -45dB null resulted with the tip at about 2.6kHz. This is proof that the Cardinal-DCR-TA is time aligned. Note that no electronics are used. The Cardinal-DCR-TA is a fully passive speaker.
Cardinal-DCR-TA Harmonic Distortion
Fig 6 – 2nd and 3rd Harmonic Distortion.
The Harmonic Distortion sweep did not reveal anything amiss with the Cardinal-DCR-TA. Distortion is generally low, averaging about -55dB below the fundamental. No unusual spikes recorded.
Fig 7 – Cardinal-DCR-TA Impedance
Power amplifiers will love these speakers. The Cardinal-DCR-TA is an easy load. The lowest is 6 ohms at 7kHz (Fig 7). Electrical phase from 200Hz onwards is within a +/- 20° window.
the Cardinal-DCR-TA in play
This speaker is about bass. It is not how loud but more the quality. Out came my favorite bass tracks.
In Fourplay’s “Max-O-Man”, the bass guitar had the right attack and tightness. In “Bali Run”, the bass kept up with the rest of the band.
Over to Santana “Supernatural”. In the recording, the bass in the opening track “(Da Le) Yaleo” is fast. The Cardinal-DCR-TA had no problem with it. It came out fast and clear. In “Maria Maria”, the Cardinal-DCR-TA delivered the body and punch in the bass. Not only that, the bass texture came out as well.
Since I’m on the topic of texture, believe it or not, Britney Spear’s “…Baby One More Time”. Listen to the bass carefully. The manner in which it pulls and pushes you. And that texture at the end of the bass note. All came out with the Cardinal-DCR-TA.
This DCR has challenged me for seven years. Now that the Cardinal-DCR-TA reveals her true colors, I am finally at peace.
Crossover Values & Box Dimensions
If you’re interested to build this project, kindly send me a mail for the crossover and box dimensions. For non-commercial use only.
November 18, 2017Projects