RAAL-requisite SR1a Ribbon Headphone Review

[Chrispy]

I found the peppers the best part. I'm not wanting to wear headphones unless forced to (like maybe during a power outage), but something like this just boggles the mind!

 

[solderdude]

I see that Raal have a dedicated driver amplifier coming. Which makes sense. They list the impedance of the phones as 0.2 ohms. The transformer box presents 6 ohms. That would be turns ratio of 1:30. But I don’t think this is the design.
The need for a 100 watt amplifier is a bit mysterious. Flat out it would cook the transformers or the headphones or both. There is a lot of heat dissipation designed into the resistors in the adaptive box. One suspects that is what the amplifier is driving. May be a lot of passive tweaking of the response going on in there. Overall the contents of the box are just as interesting as the build of the headphones.

It's just series resistors. There are also 2 huge inductors. These have to be this big because they must not saturate with 5 to 10A in low frequencies.
The driver itself is 0.02Ohm, the cable is 0.2 Ohm but because you cannot use it without the cable (which also has to be able to withstand those currents) and yet be supple enough to pass as a headphone cable that determines the load resistance.
To ensure a speaker amp (because of the needed current) can be used series resistors are added. With capacitors they also created the needed EQ above 400Hz (to EQ it down in the treble).

It's just series resistors. There are also 2 huge inductors. These have to be this big because they must not saturate with 5A in low frequencies.
The driver itself is 0.02Ohm, the cable is 0.2 Ohm but because you cannot use it without the cable (which also has to be able to withstand those currents) and yet be supple enough to pass as a headphone cable that determines the load resistance.
To ensure a speaker amp (because of the needed current) can be used series resistors are added. With capacitors they also created the needed EQ above 400Hz (to EQ it down in the treble).

To reach 5A in 7Ohm you need a 150W amp (in 8 Ohm) so that's why a >100W amp is needed/recommended.
To reach the required currents and not stress out most amps using a lower impedance (which could have been created)

The Jotunheim-R drives it directly. It has huge current capabilities but only a low output voltage so much less power dissipation.
The driver itself requires only 0.4W for 110dB peak.

The rest of the power is dissipated in the resistor box (+ some in the cable) when using it with power amps.

 

[AnalogSteph]

It's surprising enough that this even made it to market with unfavorable parameters such as these.

Ribbon headphones are basically screaming for integration of amplifying electronics into the earpieces or the headband. If you've got 20 mOhms of load impedance, you want your cables to be as short as humanly possible. I would also want to be integrating a bipolar DC/DC converter, so that the amp can be fed via 12-19 V via the headphone cable but the power stage can run on +/-1 V or whatever makes sense with correspondingly greater current capabilities. Trying to do this without any transformers may turn out to be an interesting design exercise. I guess Class D would be interesting, at least the computer world should provide lots of MOSFETs suitable for such an application.

 

[solderdude]

Why are they so expensive? Are the parts that costly? Difficult to make?

The drivers themselves are customer replaceable (they just slide in, no tools needed) and cost $350.- the pair. The rest is probably construction (in small Qty ?) and the connection box, research costs etc.
Raal is in this for the money and have no competition in this driver type. They do not aim at the average headphone buyer market.

 

[Soniclife]

My dad was in the room when I was reading this. When I showed him the headphones, his first words were- "Is that forum reviewing headphones made in peoples' garages now?"

I kind of like the mad professor look to them, but I say that as someone who is not going to be buying them or wearing them.

 

[JohnYang1997]

I kind of like the mad professor look to them, but I say that as someone who is not going to be buying them or wearing them.

I really like the look before I look closely. I thought was a metal grill housing with all polished rounded edges. But turned out to be all rough, cheap carbon fiber reinforced resin boards. ugh.

 

[3125b]

I see what they were going for with the design, but the execution is just so poor. Looks like a half finished DIY project.
I don't get the price point, judging by the performance they didn't do that much R&D ...

 

[tomtoo]

I will try that. Thanks.

Maybe try rosting them in the pizza oven? Adding some nice smoke aroma?

 

[Robbo99999]

I see what they were going for with the design, but the execution is just so poor. Looks like a half finished DIY project.
I don't get the price point, judging by the performance they didn't do that much R&D ...

I'm guessing they've got a small market so they have to charge more per unit for a chance of getting an overall profit on the entire project, also combined with the fact that there's a small minority of people/audiophiles that go for the "more expensive is therefore better" feeling/mantra, and combined with the uniqueness of design to align a little with that price & "special" feeling....no question that they are too expensive though and to me just a crazy overall design choice from the ground up (which I mentioned a few posts earlier).

 

[GeorgeWalk]

Maybe try rosting them in the pizza oven? Adding some nice smoke aroma?

The peppers or the headphones?

 

[solderdude]

For smoking the headphones you could use a 1kW amplifier.

 

[tomtoo]

For smoking the headphones you could use a 1kW amplifier.

I just wonder i this would at least for a short time would add some bass??

 

[solderdude]

Bass won't be higher.
The ribbon just cannot make the needed excursions.
It also isn't aimed at bassheads either.
You can see the problems it has in the distortion plots, the lows are very high distortion.
Fortunately our ears aren't really sensitive to such high distortions but can hear bass roll-off.

 

[Biblob]

Also, what's up with these three USB ports on the stand?
Does this headphone act as an wireless charger and the stand the receiver?

 

[tomtoo]

"..It also isn't aimed at bassheads either..."
Yes i know i think thats one of the reasons @amirm didnt.like to much.

 

[solderdude]

earlobes no shaky ...

 

[GeorgeWalk]

I just wonder i this would at least for a short time would add some bass??

Here I added some bass. Oh wait, you said bass.

 

[tomtoo]

Also, what's up with these three USB ports on the stand?
Does this headphone act as an wireless charger and the stand the receiver?

With the estimated 0.009% efficience you could charge a lot of phones with the wasted heat. I mean pumping 260w of power in there is i think about 20 phone chargers.

 

[tomtoo]

Here I added some bass. Oh wait, you said bass.View attachment 85845

 

[solderdude]

but this fish is 0.02% ! ... depending on how you look at it.