You could certainly implement the compensation curve with a tube amplifier. And you could do it either directly as part of the amplifiers implementation, as an external box, or with software EQ.
However, you would either still need a load-matching box to drive the SR1a (which is where most of the power goes) - as that interface’s PRIMARY purpose is to show the amplifier a ~6 ohm load instead of the 0.2 ohm load the actual headphones would yieldt if connected directly to the amplifier.
And a 0.2 ohm load will put the amplifier either into short-circuit protection, thermal overload, or kill it entirely.
Jotunheim R is specifically designed to drive ultra-low impedance loads, and can drop 13.2 A of current into each channel while doing so.
Tubes are much better at voltage drive than they are at supplying current, so you’d need a topology and tube choice that could handle such current levels to drive the SR1a directly - which is a totally different design approach to existing tube amplifiers and much harder to do there, than it is in solid-state design.
With your Elekit amplifier, because it’s output impedance is essentially the same as that impedance of the SR1a interface, 50% of the power it can deliver is being lost inside the amplifier anyway, so it’s effectively a 5 watt amplifier for that load.
Thanks for looking, well, listening in to this piece. I hope you have a Jot R to compare. I was planning on jumping right in myself but at $3,900 I was taking a deep breath. I need a second direct drive amp for my other set up but…
This is going to be a great shootout, all excellent options to use as a baseline to evaluate the ultimate performance of the HSA-1a. I’m very much looking forward to your impressions and review.
I find the SR1a with Jotunheim “R”, especially driven balanced, to be as transparent a sound as I’ve ever heard in a headphone. But, as a career audiophile there’s always something to look forward to,.LOL!
Tutorial on How to Use Your Standard Headphone Cables with Raal SR1a
The example will be Norne Silvergarde S3 pure silver OCC litz with 3.5 mm TRS connector.
Hifiman chose to pinout tip as positive and ring+sleeve as ground.
Raal chose 3.5 mm TRRS with tip/ring1 positive, ring2/sleeve as ground. This means I needed to desolder the wire from ring on Hifiman TRS connector; otherwise, it (ground) would short Raal’s ring1 (positive). Relatively simple to do as seen below.
Edit Reposted the earlier post with better diagram.
Already having a bunch of expensive headphone cables laying around with 4-pin male plugs, instead of making a dedicated Raal cable, I’ve decided to make 4-pin female to 4-pin female adapter to roll the other cables on Jot R (or HSA-1a).
I cannot find pre-made 4-pin female to 4-pin female adapters (3-pin and 5-pin adapters are easy to find), so if anyone knows somebody who sells such a thing, please let me know.
If not, here’s a diagram of the pinout differences between standard (Hifiman, et al) vs. Raal to assist others in making adapters or cables for Raal, whose pinouts are written in white letters, including headphone-end 3.5 mm TRRS pinouts.
***I would not recommend adapters for the Raal interface box since added resistance will be a much bigger deal there than direct drive amps.
I had emailed Nemal support to ask if their 4-pin female adapter shell was openable, and they actually emailed me back! It is sealed with epoxy, but they were willing to build me a custom adapter with the Raal pinout at the same price! Big kudos to Nemal!
So I ordered one, and I got notified that it will be built and shipped in next 3-4 days.
Those who do not want to build their own adapters may want to order one now so they can build them all together at the same time.
