• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). There are daily reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

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

PeteL

Major Contributor
Joined
Jun 1, 2020
Messages
2,749
Likes
2,953
I was thinking the same thing, and it would probably be possible to put a network in there, albeit it would make the box bigger and the impedance more complex and potentially too difficult to drive by a headphone amp. But a speaker amp could probably make short work of it, and given the driver topology has more opportunities for interacting with the pinnae and actually giving something unique imaging-wise, it would be worthwhile. At least getting the response inline with actual headphones and giving good imaging could justify a high price. As it is, its really nothing more than a ribbon tweeter shoved into a 3D printed headphone cup with some foam gasket tape on it. Cheap, nasty, and wildly overpriced.
Speaker amps or headphone amps It's a lot of components and they have to take the current. Normally analog parametric EQ are active, even if the parameters can be fixed. there I guess that hole could be helped some but it will be a complex network of high power capable passive, times two channel, with non negligible phase and impedance considerations but maybe for some cross over designers it's easy, I just don't see it.
 

Cars-N-Cans

Addicted to Fun and Learning
Joined
May 19, 2022
Messages
682
Likes
828
Location
Dirty Jerzey
Speaker amps or headphone amps It's a lot of components and they have to take the current. Normally analog parametric EQ are active, even if the parameters can be fixed. there I guess that hole could be helped some but it will be a complex network of high power capable passive, times two channel, with non negligible phase and impedance considerations but maybe for some cross over designers it's easy, I just don't see it.
Problem is most people (a.k.a subjective audiophiles) who buy this wont have any concept of the application of EQ. There are other alternatives as well such as routing the input of the DAC thru a separate box and applying the necessary corrections before it goes out to the amp and transformer box. Yeah its Rube Goldbergian to have wires going to and fro, but at least it would work out of the box. In reality, if you are designing a headphone, you can probably design some passive networks in the output path that can help straighten things out. After all, passive speakers have had such accoutrements in their cross-over networks for years and years. This would be a lot for a DIY'er rolling their own gear, but this is a manufacturer with engineering resources who should fix these problems before it even comes on the market. Most modern speakers, even ones you find in big-box stores, are not that easy to drive, anyway. Its not uncommon to see impedances dipping down into the 3Ω territory and the corrections fall at a fairly modest range of frequencies, so there is some wiggle-room to make it work. Granted its probably not as practical with many headphone amps, but it would be nice if they made it an option or an upgrade so the things actually work the way they should. I think they can probably come up with something that would not subject the amplifier to too much undue strain.
 

IVX

Major Contributor
Forum Donor
Joined
Mar 3, 2019
Messages
1,150
Likes
2,481
Location
South of China, SHZ area
The massive low-freq distortions seem to be happening by the front/rear chambers leakage, the membrane probably has the gap. Hence, this is not really harmonics but a turbulent noise. I see no way to reduce the gap down to zero due to that motor topology, maybe a wider gap may reduce turbulence but the low-frequency response is the sacrifice in this case. IMO, ribbon headphones as an inversion of a ribbon mic topology is a completely dead idea in terms of high-fidelity sound reconstruction.
 
Joined
Mar 28, 2020
Messages
52
Likes
89
Location
Baltimore
Maybe the drivers are made of RGBs



Oof.

Compare with this $140 beauty measured by Sean Olive

20221008_010512.jpg
 

solderdude

Grand Contributor
Joined
Jul 21, 2018
Messages
13,040
Likes
29,371
Location
The Neitherlands
If this transformer box is designed to be driven by a high power headphone amplifier, it's not trivial and it would be quite pricy.

Without the box the CA-1A costs $ 2k with the box = $ 2.5k
The box itself is sold for $ 650 as it can als be used for their other model but this then requires using 'baffle compensation' RCA/XLR cables in front of the amp.
One can also use this box with speaker amps b.t.w.

It can handle 6W @ 30Hz and 12W at 60Hz, 24W at 120Hz.
Above those power levels the transformer saturates (compression/higher order harmonics)
RAAL recommends amps to be used with a minimal rating of [email protected] ohm or [email protected] ohm

The massive low-freq distortions seem to be happening by the front/rear chambers leakage, the membrane probably has the gap. Hence, this is not really harmonics but a turbulent noise. I see no way to reduce the gap down to zero due to that motor topology, maybe a wider gap may reduce turbulence but the low-frequency response is the sacrifice in this case. IMO, ribbon headphones as an inversion of a ribbon mic topology is a completely dead idea in terms of high-fidelity sound reconstruction.

RAAL could (but did not) claim 0.04% THD @ 1kHz @ 94dB SL and would not be lying.
And indeed the gap on the left and right side of the ribbon could well be responsible.
A very flexible 'roll edge' could well prevent this but there would need to be some other intentional leakage that has to be introduced.
For tweeters (this is a spin off) these issues do no exist.

5% @ 100Hz is a bit on the high side.
This is a weak point of these drivers, for ortho's this happens to be a strong point.

I wonder how distortion would be with the open pads.
Alas we might not know unless @amirm can still create those plots from measurements with the open pads.
 
Last edited:

Kremmen

Member
Joined
May 18, 2021
Messages
31
Likes
65
Location
UK
AKG K371 performs very well for a very reasonable price. There are several models of Hifiman that also perform well for reasonable prices.
I couldn't agree more. I have a decent collection of headphones and I have in there the AKG K371 and the Hifiman Edition XS, both of which are splendid headphones for what I consider to be reasonable prices. (I bought the K371 new for £108 and the Edition XS new for the ridiculously good price of £347 on offer).

This is a great time to get a pair of headphones to satisfy most people's taste.
 

milosz

Senior Member
Forum Donor
Joined
Mar 27, 2019
Messages
438
Likes
1,223
Location
Chicago
In my experience measuring drivers for DIY speaker projects, ribbon drivers have MISERABLE THD levels at the bottom of their working range. The RAAL tweeters sound great above about 4 kHz, even though they have pretty flat response down about an octave or two lower (depending on model) - and their THD is lower than ribbons from Fountek, Swan or Aurum Cantus but below about 4 kHz it's still higher than most people would like in a high-end speaker. Excessive harmonics coming from fundamentals around 2 kHz are readily audible.
 

Robbo99999

Master Contributor
Forum Donor
Joined
Jan 23, 2020
Messages
5,005
Likes
4,698
Location
UK
The headphone market has been whacked for quite a while. I believe the ball started to roll around 2004ish. There has literally been no real progress made other than coming up with the next boutique "flagship", steampunk infested headphone. More outlandish styles and exorbitant prices hightens the appeal to audiophile trophy headphone crowd more than measurements.:facepalm:

Other than Sennheiser HD580/600/650, I see no reasonable performing headphone for a reasonable price out there.
HD560s too, other people have also mentioned a few others.....there are some good value good sounding headphones out there.
 

Robbo99999

Master Contributor
Forum Donor
Joined
Jan 23, 2020
Messages
5,005
Likes
4,698
Location
UK
Maybe the drivers are made of RGBs




Oof.

Compare with this $140 beauty measured by Sean Olive

View attachment 235938
Holy shmoly, that K702 measurement looks nothing like Oratory's & Crinacles measurement of a K702, and they both use GRAS rigs! Sean Olive has no bass roll off for the K702 in that measurement, and also it doesn't have the two treble peaks either. Here's the Oratory K702:
K702 v3 Oratory.jpg

Have you got the original link to Sean Olive's measurement, I'd like to check it out wherever he tweeted or posted it?
(I've got 3 units of K702, lol)
 
Joined
Mar 28, 2020
Messages
52
Likes
89
Location
Baltimore
Holy shmoly, that K702 measurement looks nothing like Oratory's & Crinacles measurement of a K702, and they both use GRAS rigs! Sean Olive has no bass roll off for the K702 in that measurement, and also it doesn't have the two treble peaks either. Here's the Oratory K702:
View attachment 236025

Have you got the original link to Sean Olive's measurement, I'd like to check it out wherever he tweeted or posted it?
(I've got 3 units of K702, lol)

That bass roll-off seems to indicate leakage. But the oratory measurement seems to be at least consistent with olive's measurement despite the more pronounced peaks. Still better than the $$2,500 'gaming' jewel imo

1665254081481.png
 
Last edited:

GaryH

Addicted to Fun and Learning
Joined
May 12, 2021
Messages
950
Likes
1,051
Holy shmoly, that K702 measurement looks nothing like Oratory's & Crinacles measurement of a K702, and they both use GRAS rigs! Sean Olive has no bass roll off for the K702 in that measurement, and also it doesn't have the two treble peaks either. Here's the Oratory K702:
View attachment 236025

Have you got the original link to Sean Olive's measurement, I'd like to check it out wherever he tweeted or posted it?
(I've got 3 units of K702, lol)
Looks like Oratory reckons it's mostly down to unit variance:
 

PeteL

Major Contributor
Joined
Jun 1, 2020
Messages
2,749
Likes
2,953
Problem is most people (a.k.a subjective audiophiles) who buy this wont have any concept of the application of EQ. There are other alternatives as well such as routing the input of the DAC thru a separate box and applying the necessary corrections before it goes out to the amp and transformer box. Yeah its Rube Goldbergian to have wires going to and fro, but at least it would work out of the box. In reality, if you are designing a headphone, you can probably design some passive networks in the output path that can help straighten things out. After all, passive speakers have had such accoutrements in their cross-over networks for years and years. This would be a lot for a DIY'er rolling their own gear, but this is a manufacturer with engineering resources who should fix these problems before it even comes on the market. Most modern speakers, even ones you find in big-box stores, are not that easy to drive, anyway. Its not uncommon to see impedances dipping down into the 3Ω territory and the corrections fall at a fairly modest range of frequencies, so there is some wiggle-room to make it work. Granted its probably not as practical with many headphone amps, but it would be nice if they made it an option or an upgrade so the things actually work the way they should. I think they can probably come up with something that would not subject the amplifier to too much undue strain.
Or they could just design better headphones?
 

Cars-N-Cans

Addicted to Fun and Learning
Joined
May 19, 2022
Messages
682
Likes
828
Location
Dirty Jerzey
Or they could just design better headphones?
True. But due to the unusual topology of using a ribbon, I'm not sure how easy that would be to fully correct in the HP itself. I'm sure it could be done, but I presume it would likely require a more advanced ribbon design to cure the shortfalls in the response, not to mention a much better cup and pad design rather than the one that looks like a cheesy 3D graphics model from an old videogame in the 2000's.
 

Robbo99999

Master Contributor
Forum Donor
Joined
Jan 23, 2020
Messages
5,005
Likes
4,698
Location
UK
That bass roll-off seems to indicate leakage. But the oratory measurement seems to be at least consistent with olive's measurement despite the more pronounced peaks. Still better than the $$2,500 'gaming' jewel imo

View attachment 236061
Looks like Oratory reckons it's mostly down to unit variance:
My three units of K702, of which Oratory measured my two older units, look like this on my miniDSP EARS rig once I've replaced the same set of pad on each of them:
K702 Beige Pads all 3 units compared.jpg
So that's somewhere between Oratory's measurement and Sean's measurement in terms of what the general shape look like from 1kHz downwards. miniDSP EARS is a "flat cheek" so optimum bass seal. My 3rd unit, the one that Oratory didn't measure is my newest that I bought this year, it's 212059 serial number, so that's not as new as the 241706 that Sean measured - I have noticed that they've changed the pads slightly through the years from 2015 (my first unit) through 2020 (2nd Unit) through 2022 (3rd unit). It'll be interesting to see Sean measure some more units, he said in that Twitter that he might get some more to verify. (Keep me posted if you see anything!)
 
Last edited:

Rottmannash

Major Contributor
Forum Donor
Joined
Nov 11, 2020
Messages
2,378
Likes
2,002
Location
Nashville
Transformers can add low frequency distortion. I could measure the box by itself but alas, I just packed it to send it its owner.
Is the box a transformer or an amplifier+transformer?
 

Rottmannash

Major Contributor
Forum Donor
Joined
Nov 11, 2020
Messages
2,378
Likes
2,002
Location
Nashville
There are also several cheaper Hifiman models worth the money, like the HE400 or the Sundara, and then you can get a used HD800 (S), which with EQ is a marvel.
...listening to Mark Knopfler on HE400i as I read this thread.
 
Top Bottom