InnerFidelity September 2012 Update
Headphone Amp Measurements
Lots of progress this month on the headphone amp measurement program. As you can see from the photo above, I've been collecting a wide variety of amps for the initial test development. It's important for Brian (NA Blur on Head-Fi) and I to have amps that will measure as variably as possible so that we can set the scaling and parameters of the testing sequence to include all possible test results. The O2 should push the lower limits; the tube amps will likely poke at the outer bounds. The SicPhones should give some speedy results with its 1MHz bandwidth. (This is an amp that will show up on Kickstarter soon, and is a single-ended, single stage, constant current source amplifier based around a newly introduced Silicon Carbide depletion mode trench JFET manufactured by SemiSouth. It's currently planned as a sub-$500 amp, and it sounded clean as a whistle and fast, fast, fast without being bright to my ears.) It's super cool to get my hands on the new Cary HH-1 hybrid amp. Haven't had a chance to listen yet, but it's hybrid design should offer an interesting measured result. Other amps to be in the mix but not in the photo are the Asus Xonar Essence One, HiFiMAN EF-6, and likely a few more.
I've been configuring the various tests on the Audio Precision tester that will be called by the main test program, and saving the data in little spread sheets. Meanwhile, Brian has his computer all set up to emulate the tester so he can develop the main program, and has finished the first pass of the Excel spreadsheet template that the data gets stored in. Brian's been a champ in the process, these first steps preparing and familiarizing oneself with computer programs are very time consuming. It's always a struggle to get things started and working well enough to get the kinks out and see a little daylight. He's made great progress---notwithstanding the flat spot on his forehead and the minor sheetrock repair he'll have to do at home. I told him to wait on the repairs, there's surely more head-banging to come. Here's the first pass on the datasheet---ignore all the problems, we're just getting started here.
Not many headphones through the lab this month but I did get my hands on the new Denons. As usual I've updated the AllGraphs.pdf of course, and added the cans to the measurement datasheets page. New additions include:
- Got the I-Mego Throne. "Who!?" you say. I'd never heard of them either, but I said okay to a PR press release just because of their resemblance to the classic Shure Super 55 microphone. Unfortunately they sounded muffled and wooly, and measured as such.
- Spider sent me their new PowerForce on-ear sealed headphone. Despite the redundant name and earpieces that look like little Apollo space capsules, this little headphone sounded pretty darn good. May be one of the better bass-head cans I've heard in fact. I'm going to have to cue up some dub step and re-listen to all my thumpers ... this may be a good little headphone.
- You know what chafes my chaps? Makers who discontinue a perfectly good headphone and replace it with something inferior. Denon did it with the AH-D1001 when they replaced it with the very colored AH-D1100. And now they've done it again ... aarrggghhh! The AH-DX000 line has been discontinued and the replacements have arrived. Despite measurements to the contrary, the AH-D7100 highest treble octave seems to have gone missing, and the mid treble is significantly blurred by some of the most horrific ringing that I've seen in a headphone. The AH-D600 fairs about the same, and the AH-D400 is missing it's top as well. I tried to measure the in-ear AH-C300, but the ergonomics of the earpieces made it impossible to insert in my dummy head. I had the same problem with my ears. I'm going to have to add a :facepalm to the smily list. Big thanks to HeadRoom for loaning me the first batch through the door so quickly.
A Big Surprise!
Since InnerFidelity's day one, I've been lobbying management for a build-a-graph tool like the one at HeadRoom. It took a while---it's a rather unusual request from a publishers point of view, usually measurements aren't that strongly desired in the audiophile world, and it's not an easy thing for non-headphone enthusiasts to "get"---but to the great credit of the team of folks around me, they did keep listening and I've recently been given the go-ahead, budget, and resources to have one built. WOOT!!!
This will be a great boon to InnerFidelity readers as it will allow you to compare graphs and post comparison plots in forum dialog. It will also make it quicker for me to write the measurement section of headphone reviews and articles with lots of graphs comparing cans as currently I have to do a lot of Excel diddling to make the plots. I'm stoked!!!
Out for a Bit
I'll be on vacation from Aug. 28 until Sept. 5. I'm riding my FJR to the Bonneville Salt Flats for the Bub motorcycle speed trials, and then to party with imaginary internet friends on a farm in Oregon. So if I don't answer your comments it's because I'll be grinning from ear to ear under my helmet.
Okay, all you youngsters out there, BACK TO SCHOOL!!!