InnerFidelity October 2012 Update
Been a good month for some unusual stuff. Stuff, unfortunately, that I can't quite tell you about. But there's some cool things I can talk about.
Let's start with this month's headphone measurements. As usual, I've updated the AllGraphs.pdf of course, and added the cans to the measurement datasheets page. New measurements include:
- You've probably seen the recent article about the Logitech UE9000 and UE6000, which measure very well in passive modes, but I also got in the UE900 IEM for measurement. I liked it even though they seem a bit bright to me. They've been sent off to ljokerl for review consideration.
- He (ljokerl) also requested a set of MEElectronics A161P in-ear headphones and had them shipped to me for measurement before listening to them for review. I liked these as well, though again, I thought them a bit bright.
- Also got in two other IEMs: PNY Midtown and RBH EP1. They just showed up on my doorstep. Probably should have just left them there.
- Head-Fi member JupiterKnight was pretty excited about the JVC HA-S500-Z inexpensive on-ear cans. They're not available in the U.S., so I told him I really wasn't too interested. But he pressed on and said I should really have a listen...my, they're pretty good for a cheap phone. I've called JVC and asked for a sample of the HA-S400, which is available in the U.S. If they're as good as the 500 they'll probably get a review from me.
Beyerdynamic Custom One Pro Measurements
I'm not sure I like them well enough for a full review, but they sure do have an interesting feature: an adjustable bass port. This four position switch on the rear of the earcups allows you to select four different levels of bass.
The image to the right shows a graphic on the packaging for the headphones, which has a graph showing what EQ change you can expect for each switch position selected. I figured I'd measure the headphones for each position. You can find the full sheets in the AllGraph.pdf and the download page, but I also made a graph overlaying all the curves, which you'll see below. It doesn't really look like what's on the box, but it is doing stuff to the bass.
Headphone Amplifier Measurements
Ugh. What a process. It's like untangling spaghetti. I've started to take various measurements with a variety of amps to get a sense of what the scaling of the graphs will be. It seems the THD+noise vs. Output Voltage is a bit of a sticky wicket. I been trying to make the test as common as possible for all amps, but it looks like I'm not going to be able to use a common set of loads or maximum voltages for all amps. The OTL tube amps and, I suspect, other high output impedance amps, just aren't going to like the 32 Ohm and 15 Ohm loads. The amps aren't designed to drive low impedances, so it's really not fair to measure the amps with them. And portable amps aren't going to deliver voltages nearly as high as home amps. Unfortunately, that means separate tests, and spreadsheets that aren't directly comparable.
Anyway below you'll find two images from the AP tester showing THD+noise vs. Output Voltage. For the tests below, I set the amps' volume controls so that with 1Vrms in they gave 1Vrms out (unity gain) and then ran the sweep from 0Vrms to 4Vrms input voltage. The following curves show THD+noise vs. Output Voltage with 32 Ohm and 470 Ohm loads.
As you can see, the tube amps (Woo, Cary), are not liking life with the 32 Ohm load. The O2 measure great until you hit the limits of its lower voltage power supply rails. Not sure why the Burson performed poorly with the 32 Ohm load. And it's pretty obvious the solid-state Apex Butte and Lake People amps need to be driven to higher output voltages to see where they start to distort. Bottom line: My idea for a one-size-fits-all amp test is likely going out the window.
Parrot Zik - I've got one in-house, and I think it's pretty cool. I've just received a Bluetooth transmitter that I can hook up to my AP tester so that I can measure wireless performance. The Zik will be the first victim. I'll go back and measure the Logitech UE9000 as well.
Sennheiser HD 650 and HD 600 - My persistent bugging of Sennheiser's PR people finally paid off, and I've just received an HD 600 to go along with the HD 650 I have here. I've been wanting to do this review for quite some time. These are a couple of great, classic cans.
Beyerdynamic DT250-250 - There's been a bit of chatter lately on the boards about these headphones, so I caller Beyer for a review pair. I've loved these cans for a long time. I'm so glad they're still making them.
V-Moda M-100 - Seems that Val has pushed the button on these, and has told me a pair will be showing up shortly. Been waiting quite a while for him to be happy with this new baby. My fingers are crossed.
Rocky Mountian Audio Fest - I'll be taking off next week Thursday for RMAF, and the whole middle of this month will be filled with reports from the show. I'm very excited! It'll be a great chance to catch up with some of the industry folks and get some gear coming in for winter. Hope to see you there!
October is my daughter's favorite month; she loves to dress up for Halloween. I grow three days worth of face fuzz and wear the same costume every year.
Scary, isn't it.