This is a review, listening tests and detailed measurements of the RAAL requisite CA-1a "true ribbon" headphone. It is on kind loan from a member and costs US $2,500.
While the RAAL SR1a required a massive power amplifier, the revised transformer can be driven from a high-power headphone amplifier which is a major improvement. The CA-1a feels more comfortable in hand but looks primitive and more like a prototype than real production. The pad especially gives that feeling as it looks like cheap open cell foam that would fall apart if left in the sun for a few days! Two sets of pads are provided: one provides full seal and the other has slots above and below.
Headband only has two sets of adjustments. While this mostly fit my head, it may not be enough range for everyone. Comfort was good except the pad was a bit rough against my skin.
RAAL CA-1a Measurements
I set up the headphone a few days ago and compared the two pads:
Both responses look terrible but at least the closed one has more conformant bass response. I think the company positions this for "gamers" and the open slot one for music.
Tonight I made a few more refinements and got ever so slightly response with closed pad which I use for the rest of the tests:
What on earth were they thinking here? That such a large chunk of the response should be taken out from 1 kHz to nearly 5 kHz? What research led them to thinking this is correct? Maybe that is why they thought the open pads sound better as the bass will overwhelm the response in treble region.
Relative response shows the large correction you need with a shape that is not easy to replicate with a parametric EQ by eye:
Distortion in bass and even midrange was extremely high:
But extremely low in higher frequencies:
Feels like a tweeter that is being told to play full range.
Drivers are slanted which may be the reason for the very messy group delay:
Given the transformer box, I did not attempt to measure its impedance. But did test for sensitivity:
Still a hungry headphone but so much more efficient than SR1a. The Topping A90 had no trouble driving it to 94 dBSPL using low gain so this is good.
Raal CA-1a Listening Tests
I used my RME ADI-2 Pro to drive the Topping A90 which in turn drove the Raal. Lack of high frequency response was so bad that it smacked you in the face! It became even more obvious when I compensated for it with EQ and then turned it off:
Without EQ, it sounds like someone stuffed some towels between it and your ear. Fortunately, EQ highly elevates the response even in the simple form I have above. Spatial qualities are excellent and high frequency detail was extremely clean and enjoyable. With the bit of bass boost I added, there was plenty of that region as well. Fidelity was very nice now and I was anxious to experience more of my reference library.
I was worried about distortion and it is indeed there. It comes in the form of ticks and then messiness/grunginess in response. Fortunately you get plenty of volume before that happens and the onset is gradual. You just don't have extra headroom on top of that to blast your ears and shorten their life.
Max usable volume with Topping A90 in high gain was 12:00 o'clock.
Conclusions
The objective measurements show a very faulty response. Given the extra box, one would think that they could put in a passive equalizer in there to compensate but they have not. The sound as such is horrid with somewhat limited dynamic range. Add a bit of EQ though and the CA-1a wakes up to something wonderful. Angled drivers provide very good spatial qualities and lack of distortion in the comfortable range for the driver provides very good fidelity.
As is, I can't recommend the Raal requisite CA-1a. But if you have to have it, use the EQ above and you will transform it to sound excellent. Whether that is the right thing on top of spending so much money is up to you.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
While the RAAL SR1a required a massive power amplifier, the revised transformer can be driven from a high-power headphone amplifier which is a major improvement. The CA-1a feels more comfortable in hand but looks primitive and more like a prototype than real production. The pad especially gives that feeling as it looks like cheap open cell foam that would fall apart if left in the sun for a few days! Two sets of pads are provided: one provides full seal and the other has slots above and below.
Headband only has two sets of adjustments. While this mostly fit my head, it may not be enough range for everyone. Comfort was good except the pad was a bit rough against my skin.
RAAL CA-1a Measurements
I set up the headphone a few days ago and compared the two pads:
Both responses look terrible but at least the closed one has more conformant bass response. I think the company positions this for "gamers" and the open slot one for music.
Tonight I made a few more refinements and got ever so slightly response with closed pad which I use for the rest of the tests:
What on earth were they thinking here? That such a large chunk of the response should be taken out from 1 kHz to nearly 5 kHz? What research led them to thinking this is correct? Maybe that is why they thought the open pads sound better as the bass will overwhelm the response in treble region.
Relative response shows the large correction you need with a shape that is not easy to replicate with a parametric EQ by eye:
Distortion in bass and even midrange was extremely high:
But extremely low in higher frequencies:
Feels like a tweeter that is being told to play full range.
Drivers are slanted which may be the reason for the very messy group delay:
Given the transformer box, I did not attempt to measure its impedance. But did test for sensitivity:
Still a hungry headphone but so much more efficient than SR1a. The Topping A90 had no trouble driving it to 94 dBSPL using low gain so this is good.
Raal CA-1a Listening Tests
I used my RME ADI-2 Pro to drive the Topping A90 which in turn drove the Raal. Lack of high frequency response was so bad that it smacked you in the face! It became even more obvious when I compensated for it with EQ and then turned it off:
Without EQ, it sounds like someone stuffed some towels between it and your ear. Fortunately, EQ highly elevates the response even in the simple form I have above. Spatial qualities are excellent and high frequency detail was extremely clean and enjoyable. With the bit of bass boost I added, there was plenty of that region as well. Fidelity was very nice now and I was anxious to experience more of my reference library.
I was worried about distortion and it is indeed there. It comes in the form of ticks and then messiness/grunginess in response. Fortunately you get plenty of volume before that happens and the onset is gradual. You just don't have extra headroom on top of that to blast your ears and shorten their life.
Max usable volume with Topping A90 in high gain was 12:00 o'clock.Conclusions
The objective measurements show a very faulty response. Given the extra box, one would think that they could put in a passive equalizer in there to compensate but they have not. The sound as such is horrid with somewhat limited dynamic range. Add a bit of EQ though and the CA-1a wakes up to something wonderful. Angled drivers provide very good spatial qualities and lack of distortion in the comfortable range for the driver provides very good fidelity.
As is, I can't recommend the Raal requisite CA-1a. But if you have to have it, use the EQ above and you will transform it to sound excellent. Whether that is the right thing on top of spending so much money is up to you.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
