HeadRoom V2 Measurement System: Bug List

As many of you may have noticed, our new measurements are up. You may have also noticed that while they're better in some ways, they aren't as good in others.

Well, we're working on it, but it'll be a bit slow going. In an effort to make it a little faster going, I've started this thread so youz guyz can make comments about things that look erroneous. We've got a really cool guy, Derren, who's a Montana State U. student who's doing his postgrad work in psychoacoustics. He's been doing the measurements. I'm gonna turn hiim on to this thread and he'll monitor it for things that need looking into.

I can only ask that you bear with us, and lend a hand by notating any problems you find.

Measurements page is here.


I'll start: the triggering on square waves is not set properly and the squarewaves don't line up. (Fix is in the works for this, but it will take a while as all headphones need to be remeasured to fix it. We are currently doing that.)


Thanks folks!

I think this got fixed, here's the graph.



Yup...sort of. One of the problems with our isolation measurement is that there is a single speaker that is the sound source in an anechoic chamber. This causes some discrete audio paths to the ear that may resonate. It would be better if we did the isolation measurement in a "live" concrete room with 8 speakers in the corners exciting and reverberating throught the entire space creating a diffuse field of noise.

They're pretty close though.




I tell you what, after we get the straight up measurements working, I'll work on doing some experiments that I post here. I'll do different cables, but I'll also do stuff like measuring headphones on different positions on the head, and the Grados with all the different pads. But for the moment I need to get the basic stuff up. Good idea though!

The old data doesn't work with the new data set (different number of samples), and we have to measure the headphones we carry first.

Yupper, there are two truths here: the objective measureable truths; and what you hear. The two are related---measurements will tell you when there's more bass, or when there frequency response is wiggly and therefore has problems---but measurements won't tell you if you hear somethings as "deeper" or more "airy." I can tell you though that the better the headphones measure, the better they generally sound. That's for sure.

There is test gear specifically designed for testing cables (they test for reflections and group delays and such), but those effects are far to small to be seen buried in the noise and much grosser features of the kinds of test we do on headphones.

I'll still give them a go, but I really doubt you'll see anything definitive.

Could be, but Darren works pretty hard to get a good seal. He knows what to look for. He's going to be cruising this thread for info, I'll ask him about remeasureing the W5000.



They've got other problems though.


BTW the D5000 and D7000 were remeasured and the measurements are up.



So that just shows to go you, there's hardly any measurable difference (at least with this type of measurement) between balanced and unbalanced, yet we all know that it makes a fairly easily audible change to hear.

Funny! Nice catch, mate.

The tricky thing is that the additional overshoot could just be from a different position on the dummy. Generally it means that the high frequencies are getting to the ear a little stronger. It really could be a lot of things besides the calbe or balanced configuration.

These are things we're going to have to figure out over time.