Fellow Raalers, I’ve been very much enjoying the SR1a and I’ve also concluded that they’re the most resolving and the best headphones I’ve ever heard to date…the details about how I came to that conclusion will be shared on another post. On this post, I would like to share my experience and lessons learned regarding the power requirements for the SR1a.
As most of you are aware, I’ve been driving the SR1a with a single SPL Performer s800 power amp (rated at 185W into 8 ohm / 285W into 4 ohm) and it did a phenomenal job unleashing the dynamics and low end response from the SR1a effortlessly. My normal listening SPL is around 70-85 dBU and I occasionally crank up to a little over 90 dBu for short periods of time. Last night I was listening to a few sub bass and bass heavy tracks such as Starlight by Jai Wold (Goldroom Remix), Exodus by Shai TTokyo Drift by PedroDJDaddy, No Harm is Done (ft Tunji Ige) by Christine and the Queens, Waiting in Vain (Boddhi Satva Afriki Soul Remix) by Groove Cartell, Maya Roze, Flip by Glass Animals… and on my attempt to crank up the volume, I heard both ribbons rattling severely hard with the volume at around 48% and I immediately lowered it.
I’ve reported the “incident” to RAAL-Requisite and both Danny & Aleksandar (the design and lead engineer) immediately got back to me. Below is Aleksandar’s explanation about the effects of too much power on the ribbon excursion levels that could potentially loosen them, thus reducing its longevity:
“ Well, the amp you’re using has a bit too much power, and the tracks were bass heavy, so when you add those two together, the ribbons will get stretched and start flapping sooner than they used to, that’s all.
Initially, I rated the headphones to 100W/8 Ohm amplifiers, encompassing all kinds of music.
Later on, we extended the rating to up to 150W for listeners of Classical music and acoustical Jazz.
For example, 150W will make the ribbon excursion 22% greater than 100W and 185W will make 36% more excursion than 100W.
With 185W/8 Ohms that you have now, I think it is too optimistic to expect nothing will go wrong with modern production on bass-heavy music.
That kind of music demands a lot of ribbon excursion and overshooting the design goal by 36% is quite a lot for the mechanics of the ribbon.
The trouble is that no matter how briefly it was cranked up, like just a fraction of a second, the ribbons will get overdriven and start loosing the original tension.
Basically, even though the bass on SR1a sounds really nice, they will never be the bass-champs in terms of SPL, so the only thing I can advise is caution with volume knob on such tracks.
I could have designed a built-in safety feature, increasing the acoustical resistance in the vicinity of the ribbon that reduces ribbon excursion when ribbon velocity increases, but in it’s essence, it would be just a dynamic compressor and the sound will become dull and dynamically flat.
So, this sensitivity to excursion, meaning volume and power, is a deliberate choice for the sake of making the dynamics sounds natural as there was no other way to do it.
To me, it’s a no brainer. I’m just cautious with my volume knob and that’s a small price to pay for the sense of unbridled dynamics.
I like my AHB2 a lot, and aside from the sound, I really appreciate it’s clip indicators. They are faster than what I can audibly perceive, but I never let them light up. That’s just an easy way for me to always be on the safe side.
You don’t really need to change the amplifier, but If you could make, or buy, a clip indicator that would be set to trigger at 42Vpeak, you’d always be aware of the power limits that I originally set and the ribbons will last you for a long, long time.
Trust me, I know 200W is a lot of fun, but I couldn’t make the best balance between all the engineering aspects of it, to say that I’m safe over 100W, so if you can live with that, I couldn’t be happier and I hope you will enjoy them for a very long time!”
As you can see, the SPL Performer s800 at full power will overdrive the ribbons causing up to 36% excursion over the design goal (@100W) which is a bit of a stretch and will most likely loosen and potentially damage them regardless of the “exposure time” to such power. My key takeaways to preserve the longevity of the ribbons are to be cautious with the volume knob if you have an amplifier rated above the recommended 100W specially when listening to bass heavy tracks and to add a clip indicator (not sure how to do that as of now) and set it to trigger at 42Vpeak as recommended by Alex so that you’re aware of the power limits that he set to avoid overdriving the SR1a.
That’s all I had…now I’m going back to listen to the SR1a….
