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RAAL requisite CA-1a Headphone Review

Rate this headphone:

  • 1. Poor (headless panther)

    Votes: 169 82.4%
  • 2. Not terrible (postman panther)

    Votes: 24 11.7%
  • 3. Fine (happy panther)

    Votes: 7 3.4%
  • 4. Great (golfing panther)

    Votes: 5 2.4%

  • Total voters
    205

amirm

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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.
Raal requisite True Ribbon Headphone Review.jpg

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:
Raal requisite True Ribbon Headphone Pad Frequency Response Measurement.png


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:
Raal requisite True Ribbon Headphone Closed Pad Frequency Response Measurement.png


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:
Raal requisite True Ribbon Headphone Closed Pad Relative Frequency Response Measurement.png


Distortion in bass and even midrange was extremely high:
Raal requisite True Ribbon Headphone Closed Pad Relative Distortion Measurement.png


But extremely low in higher frequencies:
Raal requisite True Ribbon Headphone Closed Pad THD Distortion Measurement.png


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:
Raal requisite True Ribbon Headphone Closed Pad Group Delay Measurement.png


Given the transformer box, I did not attempt to measure its impedance. But did test for sensitivity:
most sensitive headphone review.png


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:
Raal requisite True Ribbon Headphone Closed Pad equalization eq parametric.png


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.

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As always, questions, comments, recommendations, etc. are welcome.

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  • Raal requisite True Ribbon Headphone Closed Pad Frequency Response Measurement.zip
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thewas

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Add a bit of EQ though and the CA-1a wakes up to something wonderful.
That shows again that the audibility of hamonic distortion gets usually overestimated, would be interesting to see some multitone distortion comparisons with better HD measuring headphones as my guess is that those might correlate better with audibility.
 

DanielT

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Thank you Amir for the review, listening tests and detailed measurements. :DExpensive money for poor performance. :oops:Good consumer information!

Distortion in bass and even midrange was extremely high.
I remember that I read about those who DIY ribbon speakers that they are advised not to add a transformer in the construction because it can easily lead to quite high distortion. Could that be true and is it perhaps what causes these headphones to have such high distortion?:rolleyes:

But it may not have anything to do with the transformer because: But extremely low in higher frequencies....
What do I know.:)
 
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amirm

amirm

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I remember that I read about those who DIY ribbon speakers that they are advised not to add a transformer in the construction because it can easily lead to quite high distortion. Could that be true and is it perhaps what causes these headphones to have such high distortion?:rolleyes:
Transformers can add low frequency distortion. I could measure the box by itself but alas, I just packed it to send it its owner.
 

solderdude

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@amirm For the sensitivity measurement did you use the 16 ohm or 32 ohm input ?
93.5dB/V is very low and when this is in 16ohm you need quite a lot of power (voltage and current) to drive these to impressive levels.
At 114dB SPL (assuming 32 ohm input was used which is advised by RAAL) it required 10V = 3W
When you were to use the open pads and want Harman bass you need 3x at 30Hz.
Acc. to Raal the transformer saturates with 6W at 30Hz (12W at 60Hz)

Would have been fun to see measurements of the transformer box (under load)

The CA-1A seems to get glowing reviews.

€ 3k in E.U. (due to import taxes)
 
Last edited:
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amirm

amirm

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@amirm For the sensitivity measurement did you use the 16 ohm or 32 ohm input ?
Sorry, forgot to note it before I dismantled it for the picture. But I think it was 32 ohm.
 

Robbo99999

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I voted this headphone "Not Terrible", but that was only saved from "Poor" by Amir's judgement on it's spatial soundstage qualities, and I almost didn't upgrade it for that because soundstage assessment is quite an individualised experienced. Distortion is just terrible in the bass, along with the stock frequency response whose only saving grace is that channel matching seems pretty good and the response was generally free of horrible sharp dips or peaks which means better EQ'ing ability - it's still a rubbish frequency response at stock though. It's one of those headphones that I suppose you have to listen to in order to judge if the soundstage is really that good that it can override all the other negatives & if the bass distortion is really that visible - given the measurements I'd expect the bass distortion to be detectable. Very expensive headphone too. Impossible to mark this headphone higher than "Not Terrible" based on the measurements unless you've listened to it and think the soundstage is superlative.
 

Koeitje

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I think the company positions this for "gamers" and the open slot one for music.
That's so weird, because the bigger brands aim for a pretty neutral sound. In a lot of situations these headsets are also used to listen to music. This is pretty decent for a gaming headset for example (just lacks bass):
 

LunaTempesta

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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.

Hefty price tag if they aim it at gamers.
 
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