[jwbrent]

Tube watts and solid state watts don't feel like they are the same. My 75 Watt tubed monoblocks power my speakers like 150 / 200 Watt solid state monoblocks.

I bet it will be close.

Especially with KT88s...

Can your amp accommodate KT90s or KT120s? If so, that may tip you over the edge.

I plan to run the SR1a with my 75 wpc tube monoblocks as well as my 200 wpc stereo amplifier.

You can always try it and then adjust accordingly...

That’s the right ratio ... tube amps due to producing even order harmonics when clipping still sound great. So halve the solid state wattage to get an equivalent output level provided the impedance of the speaker isn’t atypical.

The first time I checked out the RAAL website, it stated a 150 watt/ch amp was required. When I visited the site earlier today, I noted the wattage figure was down to 100/ch. That’s why I asked @RAAL requisite Alex if they had any experience using a lower powered tube amp.

I love ribbon drivers. I owned Apogees in the 90s and loved its sound. I now have Raidhos which use a proprietary ribbon tweeter, the best high frequency transducer I’ve ever heard. I believe my Luxman can use KT90s with little bother since it’s a manual bias design with a meter.

Your monoblocks should do the job. Please post your findings after you get the SR1a, I’ll be very interested in your thoughts ...

Last thing, I love well designed audio product, and the SR1a has a killer look to it—I love the carbon fiber build.

This hobby is so crazily addictive. I just bought a final D8000, its new top end planar, a month ago and they are fantastic sounding; now a month later I’m already fantasizing about a new TOTL headphone.

 

[jwbrent]

High end audio is a drug ... it puts one in a state of ecstasy.

 

[jwbrent]

I looked at the web site further and the load to one’s stereo amp is listed as ~6 ohms, so not a difficult load at all. The sensitivity is 91dB with 1 watt. By my calculation, I should be able to get a 106dB output, even a bit higher since I’m not factoring in headroom.

Very interesting.

 

[Zhanming057]

Hi Alex,

I’m intrigued by your ribbon headphones. My question is whether a 50 watt/ch, KT88 based tube amp will be sufficient to drive these headphones. My Luxman MQ-88 is conservatively rated, and since we’re only talking about a 3dB difference in output compared to the 100 watt/ch recommendation, I’m wondering what your thoughts are.

I've put the SR1A's on 75wpc KT150 and 80wpc KT88 tube amps and couldn't notice any power delivery issues. In contrast 50-75wpc solid states all have some fairly noticeable problem with bass extension at loud volumes.

I won't say for sure that 50wpc is enough for a KT88 but if you're not listening loudly, it's probably going to work just fine.

Also, my understanding of the official recommendation is at least 150 wpc into 4 ohm or 100 wpc into 8. The latter is a bit closer to the actual performance conditions of the headphones, since the box is designed to max out at 150w of input.

 

[jwbrent]

I've put the SR1A's on 75wpc KT150 and 80wpc KT88 tube amps and couldn't notice any power delivery issues. In contrast 50-75wpc solid states all have some fairly noticeable problem with bass extension at loud volumes.

I won't say for sure that 50wpc is enough for a KT88 but if you're not listening loudly, it's probably going to work just fine.

Also, my understanding of the official recommendation is at least 150 wpc into 4 ohm or 100 wpc into 8. The latter is a bit closer to the actual performance conditions of the headphones, since the box is designed to max out at 150w of input.

Thank you for your thoughts. There is a free trial period offered, and that is the only way to know for sure. I love the aesthetic design and sound of my Luxman amp, so no changes there.

 

[Zhanming057]

@bearwarrior You can check out additional technical details by following @RAAL requisite Alex 's posts here.

 

[HoloSpice]

Anyone tried the SR1A on a Schiit Vidar?

 

[WilliamWykeham]

@RAAL requisite Alex

If one were to remove either the interior white foam or the exterior dark foam on the SR1a, what would happen?

 

[joseph69]

@RAAL requisite Alex

If one were to remove either the interior white foam or the exterior dark foam on the SR1a, what would happen?

There would be no foam.

 

[Aleksandar R.]

@RAAL requisite Alex

If one were to remove either the interior white foam or the exterior dark foam on the SR1a, what would happen?

If you would remove all foam, a 10dB peak at ribbon resonant frequency would appear, same like with any other headphones when you remove the acoustical resistance.

 

[WilliamWykeham]

If you would remove all foam, a 10dB peak at ribbon resonant frequency would appear, same like with any other headphones when you remove the acoustical resistance.

Thanks. Reason for asking was curiousity about whether foam was for protection or sound quality. My Sierra 2 speakers were dramatically improved by removing the protective screen. But sounds like this is different.

 

[Aleksandar R.]

Thanks. Reason for asking was curiousity about whether foam was for protection or sound quality. My Sierra 2 speakers were dramatically improved by removing the protective screen. But sounds like this is different.

It is somewhat different in this context as here, its function is more like the internal speaker-box dampening.
The white foam that we use is melamine, quite stiff and very thin, so very low absorption of highs, meaningful only above 20k. Also, it has certain properties that are very favorable if you want acoustical resistance with the least amount of absorption. The best in that ratio are woven metal meshes, but may show resonance, so stiff foam is the best overall.
We use melaminet inside and outside, plus on the outside there's another layer of polyurethane foam.
I can't get by with use none on the inside (and add the same layer on the outside to keep the total acoustical resistance to be the same) as then the modal resonances on the ribbon are not controlled very well.
However, I used the very least thickness possible on the inside. If you light it with a flashlight from the inside, you will easily see the ribbon underneath it. The rough rule-of-thumb is that if something is visually transparent, it will be acoustically transparent, as well.
In any case, due to low res. frequency of the ribbon and some other tricks, I use very low amount of acoustical resistance and that's why these things excel in dynamics.

 

[Bill13]

We use melaminet inside and outside, plus on the outside there's another layer of polyurethane foam.

Alex, your successful application of acoustic materials is impressive.

However, I wonder if the layer of polyurethane foam can deteriorate in a few years?
In the past, I've seen foam surrounds in loudspeaker cones weather, and turn into sticky black 'goo' with a molasses-like consistency.
Do you use a special kind of polyurethane foam that resists chemical deterioration over time?
If not, can we eventually buy, or get new polyurethane foam layer self-repair materials which we can insert into the SR1a headphones by ourselves? Just wondering.

 

[Bill13]

Comment about the Imaging ability of the SR1a headphones: Great sound staging.
The ability my Raal SR1a ribbon headphones to place the sound source is {IMO} amazing - even can hear sound apparently coming from the rear, that is, seems to be convincingly located behind me -- while using my particular setup, anyway.

My setup uses the Redscape program with its included gyroscopic-head-tracker. When I turn around, facing away from my video display monitor, the head tracker signals the program to move the sound stage to my rear {see virtual-head picture thumbnail below}. Currently also using Redscape to apply a digital EQ that I feel is similar to the "-3R" de-emphasis, or maybe as much as the "-4R" de-emphasis, as previously discussed --
Also, I personally chose to add a few dB of {digital EQ in Redscape} low-bass-boost for my SR1a.

Edit: After many tries, I wasn't successful uploading this image as a small thumbnail -- sorry.

 

[Aleksandar R.]

Alex, your successful application of acoustic materials is impressive.

However, I wonder if the layer of polyurethane foam can deteriorate in a few years?
In the past, I've seen foam surrounds in loudspeaker cones weather, and turn into sticky black 'goo' with a molasses-like consistency.
Do you use a special kind of polyurethane foam that resists chemical deterioration over time?
If not, can we eventually buy, or get new polyurethane foam layer self-repair materials which we can insert into the SR1a headphones by ourselves? Just wondering.

Yes, you can pry out the grille and take out the old foam and insert the new one. Black foam is not glued, just put in place, so taking it in and out is trouble-free.
The greatest enemy of polyurethane is UV radiation so in an effort to prolong its life, we chemically dyed it black. Hopefully, this will block the UV to a certain degree. i don't know for how much, but it'll do at least some blocking. Also, it is stationary, no flexing or carrying weight, so it should live for a long time.
The dye bonds itself to the polyurethane in a very thin layer and the reaction stops when the whole surface of the foam is covered, as the dye doesn't bond to itself, just to the remaining exposed foam. This happens throughout the foam volume, so when you cut it, it's colored in the middle, as well.
We use this method to get that rich Requisite-red color for the cushions, as you can't buy Memory-foam in any colors and we really wanted that Requisite-red. Actually, you can't buy even a regular polyurethane foam this dark black, also. It's always dark-gray rather than truly black, so that was another problem to solve...