Super Best Audio Friends

When I started to look at how to effectively integrate my REL R-305 subwoofer with a pair of "mains" speakers using a statistical approach called Design of Experiments to optimize integration of subwoofers for a given room with a set of "mains" speakers.

To start with here is an introduction to Design of Experiments.

Description
Design of Experiments (DOE) is a powerful tool that can be used in a variety of experimental situations. DOE allows for multiple input factors to be manipulated determining their effect on a desired output (response). By manipulating multiple inputs at the same time, DOE can identify important interactions that may be missed when experimenting with one factor at a time. All possible combinations can be investigated (full factorial) or only a portion of the possible combinations (fractional factorial). Fractional factorials will not be discussed here.

...

An example trace as my starting point for reference is shown. The purple trace is where I started with the sub in, the brown trace with the sub out, before optimizing things using the DOE approach. The following is the real-time, IN-ROOM measured response for the right speaker:

I just saw they’ve released a new, higher-end Phono stage: the Skoll… https://www.schiit.com/products/skoll
Figured we’d need a thread (didn’t see one on searching).
Anyone out there tried it? I really like the price (a lot), and am sorely tempted.



MOD EDIT - Impressions start here: https://www.superbestaudiofriends.org/index.php?threads/the-just-announced-schiit-skoll.13874/#post-418411

It's been a while since there has been a Socal meetup and a few of us have decided to organize a casual meetup.


When/Where:
The event will be on Sunday Nov 12th from 10AM - 5PM. The location has been finalized - it is going to be in a ~900-1000 sq ft hotel conference room by the 5 freeway and Disneyland. I will PM the venue and address to those of you who are attending. You can stay for as little or as long as you'd like and can come and go freely.

Cost:
It will be $28/person to attend - this is to cover the cost of the room, taxes, and other associated fees (I have already paid for the venue). There will be no charge for parking and you can exit/enter anytime with no extra parking or other costs. To book your spot, please PM me and I will provide you with a paypal address for payment. For now, no refunds after Wednesday 11:59PM Nov 8th as it's too much to shuffle people around with less than 2 days before the event. If you need an alternate way to pay OR are not comfortable sending money to me individually, we can discuss via PM and work something out through SBAF as well,

Recently, I was jamming out to my Olina SEs on an Apple Dongle and wondering why I had so much expensive equipment on my desk when this sounded fine. Still, I didn’t want to give up my Custom Cans-modded HD6XX, my Atrium, or my Bottlehead Crack. But since I got the Crack, I’d been using my RebelAmp a lot less except as a Preamp for my cheapo speakers (I’m not able to use speakers much because of my living situation). I did have a Schiit Bifrost 2/64, but if the Apple Dongle sounded pretty good to me, did I really need something so expensive? Anyway, the 2/64 seemed to add a little bit too much, I don’t know, texture? Graininess? Something. Anyway, I also have a Schiit Modi+ in my closet and that sounded pretty good, but what if I replaced the Rebel and the Bifrost with a nice, compact little package that wouldn’t take up much space on my desk? What if I replaced them both with the inexpensive, feature-rich, and well-reviewed Fiio K7 Pro? Think of how much money and desk space I could recoup then!

So I bought the K7, plugged it in, wired it up and…

And it was terrible. Just glare-city, glassy, overbearing treble without much depth or detail. Keep in mind I’m listening to this with the HD6XX and the Atrium, and in both cases using the balanced out so getting the (theoretical) optimum experience. Likewise on my cheapo Edifier R1700BT speakers, there was a glare and treble that I’d never experienced with the Bifrost/Rebel setup.

How does this thing have so many good reviews? I’ve even seen people on Discord say this is the default budget recommendation over the Modi/Magni stack. Is there something fundamentally different about my hearing from other peoples? Because this thing sounds unbearable to me, and it clearly doesn’t to a lot of people, I just don’t get it.

But this isn’t the first time I had an experience like this. My first proper DAC/amp was the Zen DAC which I loved and paired with a Sundara. I then added the Zen Can to it and thought it was even better.

Estron provided the DualBaX Zebra cable reviewed here. I normally don’t talk much about cables beyond always desiring thinner IEM cables that are soft, pliable and with little to no memory. Ever since I first handled a Linum cable nearly a decade ago, I have been a fan of their approach to cable design. Their design aesthetic matches my own- simple, minimalist and functional.


Photo from Linum product page

Back in 2014 I first became acquainted with Linum cables, when I reviewed their OG BaX balanced cable for Cymbacavum. That particular model, along with the Music and Vocal models, are the thinnest they make. According to my old review, that model was 0.9mm in diameter and weighed around 2.7 grams (0.095 oz), although the newer generation may weigh slightly more. That’s a seriously thin cable. It had a pull strength of 60n/13lbs, so it was fairly durable considering its minuscule size. The OG BaX was joy to wear, as it was virtually invisible and completely disappeared with regards to feel over the ear, even when wearing glasses. The downsides were that model tangled really easily and was a bit of a bear to untangle. Also, due to the light weight, heavier IEMs couldn’t just be dangled over your ears, if you removed them to talk to someone. Perhaps another downside to such a thin cable, or perhaps a benefit depending on use-case, were the impedance specifications:

Vocal: 3.9Ω (out of production)
Music: 2.0Ω
BaX: 1.5Ω

Moondrop has largely made their fame by creating IEMs that hit certain target responses pretty reliably - be it Harman or Crinacle's. Of course, it's up to you whether you subscribe to that target.



Enter the Moondrop Para. Not their first foray into full-size cans, but I'd say that it's their best.



Both are supposed to be measured on the same rig, so the curves should be comparable.

So let me do a quick summary. A while ago, and this was on the tail end of the AmirNAD fad (SINAD at full scale, 1kHz stimulus, 20kHz bandwidth, 100/200kHz loads for SE/BAL respectively), Jason decided to hop on board because Texas Instruments had a new DAC chip that could do up to 120db AmirNAD. It wasn't an audio chip, but the given the DSP chops of MM, Dave, and Ivana, it wouldn't be much of a problem to get audio data into the chip. The chip in question was this: https://www.ti.com/product/DAC11001A



So I guess the story is that TI calls @schiit and tells him: Hey, we have this new B version that fixes the measured ultrasonic f'ery. Wanna try it out. Of course we know @schiit will not refuse, at least to try it. And thus voila, the MIL-B (or whatever it's going to be called). I asked Jason if I could borrow this because, you know, we like real science here. Actually exploring and learning new things is fun! Sticking to an old dogma is dumb (and yes, the THD+N cult has been around forever, read up on Doug Self)

So fast forward a bit, I pick up a Mjolnir 3 for myself and try out a few DACs to see which ones I preferred best, you know, the synergy thing. Turned out the DAC11001B based MIL-B was the winner. Not only that, but the MIL-B had been baking for a few weeks now. With a more resolving setup in front of me, I didn't realize how much it had changed.

I hadn't intended on covering the Midgard so soon after its release, but there seemed to be quite a bit of interest in this product, particularly the Halo topology. Some deal about error correction by incorporating the transducer in the feedback loop. I haven't read into the papers on this really, so I can't say much. The Halo thing only works through the XLR output for obvious reasons. One noted downside is higher output impedance, 2-ohms in this case. I figure the reason we never saw this much with speaker amps could be this higher output impedance. As with most things, I am guessing that by the time the paper(s) on how to do this came out or become well known, the industry was obsessed with "damping factor". Yeah, the audio industry goes through fads too. There is a reason why some speaker amp designs in the early 80s, even by guys who were really good at discrete designs, used opamps. THD was a selling point at that point in time (thanks to Doug Self). Eventually people stopped caring about THD. Until NWAVGUY. Then NWAGUY disappeared for a few years. Only for Audio Science Review to appear and take the THD zealotry to the next extreme.



That being said, I will offer my subjective impressions. I would have liked to do a blind test with the ABX machine. However it's not possible to hook up an ABX test with a balanced and single ended output because the comparator machine is SE only.

Too hard to do. Personal preferences are different. There's the ortho vs. dynamics thing which cannot be reconciled. Throw in the source or amp first people in this argument too. Then there are people more sensitive to timbre in the low-mid treble, which takes me out of the running from many TOTL planars. But then again, I shouldn't speak because I'm OK with the funky upper-mids of Grados, which many people are not. And then there are people who get annoyed with timbre of metal diaphragm dynamics. About ten or more years ago, some guy on Head-Fi wrote a big comparison on various headphones. What he wrote really hasn't changed much.

Inspiration from Battle of the Flagships by David Solomon
Credit: https://www.head-fi.org/threads/battle-of-the-flagships-58-headphones-compared.634201/

Nice nod to Changstar back in the day!

BACKGROUND - WHERE I AM COMING FROM
I only like the HD800S under certain conditions. The frequency response of the HD800S, despite the Armin Zola resonator (that lessens the 6kHz peak) is still bit too screwy for my tastes. I find that EQ doesn’t work well for the HD800S because its screwy frequency response is caused by super early reflections from how the driver is suspended and angled in front of the ear and by the large ribs and mounting structures of the cups. The treble is hot, the mids are recessed, and the lows are a bit cloudy (the HD800S took a slight step back in the lows), especially compared to the awesome low-distortion planars available today.

This guide should still be applicable to those with the OG HD800 with mods (BTA, Sandevistan, Superdupont, etc.)

As far as amping, tube amps are recommended, but solid-state amps are definitely getting there. What we are looking for is one or more of the following traits:

1. Wetness or bloom (the HD800S can be on the dry side)
2. Smooth highs (to counter the hot and grainy HD800S highs)
3. Commits few sins of omission, capable of rendering microdynamics and microdynamics (the HD800S is super resolving, subpar gear and subpar recordings won't make the HD800S any more special than lesser headphones)
4. Capable of slam (the HD800S can hit like a truck with the right gear)

Also, tube amps which are overly warm, syrupy, slow, or romantic (cathode follower OTL designs, OPT with cheap output transformers, Chi-Fi push-pull cathode bias, etc.) will not be mentioned. They do cure the HD800s dry sound, but at too high of a price in terms of clarity, transient response, microdetail, microdynamics, etc. Personally, I think you are much better off with an HD650 and LCD-2 with a very technically and musically capable amp. If you like the romantic smoothed-over-to-shit kind of sound, best to seek advice somewhere else. Trying to make the HD800S into sounding like an LCD-2 is plain wrong. It's like trying to convert someone who is gay into being straight.

Grados elicit strong reactions from the headphone community. Many readers may be too young to know that during the infancy of headphone audio, before the start of Head-Fi, and even for many years after, there were two big camps in headphones: Sennheiser vs. Grado*. Tyll of Innerfidelity** was known for not saying much about Grados. If we could corner Tyll, we may get him to admit that he didn't care much for Grados.

Most veterans today who wield Sennheisers, Audezes, HFMs, will admit that they had owned a higher-end Grado in the past or at the very least started with a Grado. The entry level Grados were (and still are) cheap, accessible, and didn't need an amp. I myself gave up on Grados in favor of Sennheiser after a period time only to come back. After so many years without Grados, I had realized that I missed Grados' punchy mid-bass, snappy transients, lively reactivity, crunchy mids, and woodie reverb/decay. Today I still have my JAR600, but it's always with a Grado next to it. The RS1X is always in my backpack.

Grado in my backpack

These are the PS500e. @rfernand sent them to me for science. Based on memory from a long time ago, I thought they were bassier. Maybe I was thinking PS1 or maybe the PS500e I heard were from of an amp with higher output impedance. Tonally, the PS500e, with the included L cush pads, measure with the classic Grado frequency response, tilted upwards, some midrange emphasis (although less crunchy), and punchy midbass (with tube amps). Being from the e series, there's a bit of sssss in the mid-treble above the sibilance area that emphasizes definition similar to the RS2e. The high end is quite airy too. Despite the bright tonal balance, I find the PS500e to be quite livable even with the L cush pads without the coarseness compared to the lower end Grados (where I prefer the F pads). Perhaps the wood inner cups (the outer are metal obviously) helps to mollify the edge or coarse of the highs.