looking for FR graph for w3-871

[kifeinthesink]

Im trying to establish a rough calibration of my ecm8000 mic and the best method I can think of is to measure a driver and compare my measurements to others that are presumabably accurate.

I have a few tangband w3-871 drivers but I haven't been able to find a FR graph on google or here.

Does anyone know where I might find one?

Thanks.

-David

[Cal Weldon]

Just the spec sheet graph, not sure if it's enough. Click on the first link and then PDF link at the bottom of that page. Disregard the attachment link in this post, it doesn't work.

http://www.partsexpress.com/pe/pshow...TOKEN=45024676

[kelticwizard]

Here's an enlargement of that chart, just in case you find it useful.

[critofur]

Originally posted by kifeinthesink
Im trying to establish a rough calibration of my ecm8000 mic and the best method I can think of is to measure a driver and compare my measurements to others that are presumabably accurate.
-David

I think you will get better results simply using a "generic" ECM8000 mic calibration file, because: the difference between one batch of those speakers and another is most likely greater than the difference between two batches of ECM8000 mics, which, are VERY flat from 50hz to 15,000hz (maybe even 18Khz?) as far as I know. I think they are generally off a couple db by 20Kz, and, at the top end is where I've seen more variation between them, IIRC.

edit: one thing we know for sure: Tang Band's graphs are certainly less accurate than using a generic mic cal file :P I think they are made by the marketing dept. and not by engineers!

[kifeinthesink]

thanks for your replies.

At one time I had measurements for this driver and they bore little resemblance to the manufacturers sheet.

I was reading a discussion about this microphone and apparently it varies greatly from batch to batch, even to the point of using different parts. Can't remember where this was but it might have been here. Most of the response measurements I've seen on the web look similar, so it would be likely that mine is similar to these, but I hate to think of investing time into a project only to discover that my measurements were wrong to begin with.

I suppose I'll have to take a leap of faith or send it off to Kim Girardin.

-David

[critofur]

Originally posted by kifeinthesink
thanks for your replies.

At one time I had measurements for this driver and they bore little resemblance to the manufacturers sheet.

I was reading a discussion about this microphone and apparently it varies greatly from batch to batch, even to the point of using different parts. Can't remember where this was but it might have been here. Most of the response measurements I've seen on the web look similar, so it would be likely that mine is similar to these, but I hate to think of investing time into a project only to discover that my measurements were wrong to begin with.

I suppose I'll have to take a leap of faith or send it off to Kim Girardin.

-David

Where is the crossover range? Do you see variation in ECM8000 mics in THAT range? Most ECM8000s seem to have a slight rise above 6 - 10 Khz or so, with more rise in the last few Khz up to 20 Khz. Almost all that I saw calibrations for showed them to be very flat up to at least 5 Khz, and you'll probably be crossing over below that freq. no?

If you use your ECM8000 with a "generic" cal file, I bet the only part that could (but not nesc) end up being off would be the top end, which, is the easiest part to tweek by just adjusting the value of an lpad resistor, or, maybe, a small change in cap value?

[Pano]

Funny - I was just looking at the W3-871 graph yesterday. Sure doesn't look like the one published a few years back. Maybe the driver has changed? IIRC, the old plot showed a big bump at about 10KHz.

Also, don't forget the the HF bump in the plot of the mic is due to using it on axis. It isn't really meant to be.