It should be, it’s a parallel (ladder) stepped attenuator. There are only two resistors in circuit per channel per step. They are precision matched between left and right channels.
Most other stepped attenuators are serial designs. So, for 24 positions, ALL 24 resistors are ALWAYS in circuit. And any error in matching between channels is cumulative.
Is there any advantage to being able to use the lowest gain setting if it meets ones loudness requirements?
It’s not a “gain” setting, it’s an attenuation setting.
Each progressively higher setting adds a couple of resistors inline, so the purest path would be 0 dB (no attenuation). I doubt you could hear or measure the difference.
Regardless, as long as you can reach the volume levels you want with it in its current position there’s no compelling reason to move it.
The attenuation settings are really there to allow use with both studio/pro gear, that has much higher output levels than consumer/audiophile gear, WITHOUT needing a gain stage (which by definition would add noise and distortion).
And to be clear … because it’s an attenuation setting, the 0 dB configuration will give the loudest output for a given input level and volume setting, and the -10 dB configuration the quietest.
So, here’s a curiosity: As I started listening today and doing some casual listening to the HSA-1a and JOT R I decided to reset the attenuation to -10db from the -6db as delivered to me. (turns out I prefer the range I get to use with the volume control at -10db).
After I got the lid off I’m staring at it and something struck me as odd.
MY UNIT
TORQ’s UNIT
Looks like the little PC board with switches is installed backwards or the opposite of Torq’s?
It looks like the resistors and DIP switch block on the vertical board have been moved to the opposite side of it. The actual connections and components/placement are the same. So it is probably a change made for ease of access or assembly and won’t have audible/performance implications.
But yes, that is different to mine.
Part of the SN gives me the thought that it was manufactured 11/20
When the fuse goes, no red light, no click when you turn the power on, no anything. I know from experience; my unit is an early HSA-1b and shipped with the 1.6A fuse (matching the labeling of the fuse socket). It blew within two weeks. Contacting RAAL, they recommended switching to a 3A fuse. Got a small box of them from Amazon and unit has been working fine since.
FWIW, my unit has the dip switch block the same as Torq’s. It also came with the same -10db default. (I’ve changed mine to 0db to better match my other gear.)
3 amp fuse on mine, as well.
Good to know, I’ve got a 2 amp coming in the mail, but so far so good with whatever is in there presently (I figured it was the original spec 1.6A). If I have reason to reposition the HSA-1a I’ll check to see what is in there.
The switch to -10db is just right for me, most CD’s so far bloom, sound wise, between 10 and 12 o"clock with the single ended input. And I love the numbered scale around the volume knob and the accurate, positive feel to the detentes, makes returning to repeat volume level settings a breeze.
After matching sound levels yesterday during the day I spent some time comparing the HSA-1a w/wo Loki to the JOT R w/wo Loki and my PrimaLuna EVO 400 with interface through both balanced and single ended inputs. Serious fun! Then a couple hours last night with just the HSA-1a.
No need to do any extensive review by me, Torq nailed the sound with his.
But of course I will make a few comments along the way in getting to know the HSA-1a.
Because that’s what I do, LOL!
Bonus gift that came with my HSA-1b: 4’ Blue Dragon AC cord. Standard Schiit AC cord in center.
that is a nice extra,I didnt get that
your source must be much louder than mine into the amp because I have to use the sr1a output and listen between 10-18 normally and I adjusted the setting to zero inside the unit…interesting
I set mine to -10db and my source (Yggdrasil 2) delivers around 4 volts in balanced and 2 volts in single ended (and I think most of the consumer gear I’ve ever owned delivered those values. I’ve sampled a number of different CD’s at this point and depending on which input I use I find myself dialing in between 9 and 14.
When I used the factory setting of -6db I got the sense that the sound was being forced/stressed.
Listening to my HD 800 and 800S today, wow, what an amp. The one amp to run them all.
I listen to my chord dave at I guess it would be 3v I believe…and need more volume than you describe listening through roon and my hard drive via a sonictransporter…I do agree it is an outstanding amp…incredibly clean and detailed not just with the sr1a but also with my susvara and abyss which makes it a jack of all trades and interestingly I find the amp imparts a similar sound signature to the susvara and abyss as one hears with the sr1a…expensive but on a relative basis as everything is well worth it
Recently received my HSA-1b amplifier, but it would not work from the XLR inputs. Contacted Danny and David, who apologized and shipped me a replacement right away. Turns out there were faulty relays in the XLR circuits of the original amp.
Happy to report that the replacement HSA-1b works perfectly. Lots of listening ahead.
Many thanks to Danny and David for dealing with this quickly and efficiently.
I think I’ll give it a go with my 1266 Phi tomorrow. Eventually I’ll probably move the HSA-1b to my upstairs rig in “the cone of silence”. There I can have it go head to head with my Formula S/Powerman.
Because of the nature of the open baffle design I’ve had a number of occasions when even distant sounds from somewhere else in the building or outside can be intrusive. The bedroom is the quietest room in the house.
So I meant to leave my office and head home two hours ago.
But the combination of my Roon Nucleus > dCS Bartók > HSA-1b > SR1a “earfield monitors” and Roon Radio have kept me glued to my chair.
One “eargasm” after another; this is what this hobby is all about!
I also have the formula s/powerman which I have used with my susvara and abyss TC…it is fantastic …the hsa-1b holds its own with the formula s/powerman combo…i think the combo has a bit more grunt and deeper bass but the hsa-1b is incredibly clean and dynamic and a hell of a good amp