Fostex F120A measurements !!!!! - diyAudio
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Old 17th July 2006, 12:59 PM   #1
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Post Fostex F120A measurements !!!!!

I have bought a few days ago some F120A drivers at a bargain price (126 each, instead of 250 !).


I mounted them on an Open baffle of approx. 40cm*35cm with 10cm deep walls.

And I could do the measurements I could never find on the Internet.

My setup is actually quite poor :

- Nvidia 24bit/96kHz motherboard-integrated soundcard (high noise, poor THD)
- DIY microphone with preamp (see my website for details)
- no SPL calibration
- measurements made in a 14m room, with no particular treatment. Maybe the weakest point of the setup...

So, let's roll and begin with the frequency response at 1m !
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Old 17th July 2006, 01:03 PM   #2
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Then, distorsion measurements taken at 37cm of the driver (the orange curve)

The SPL was around 85dB at 1 meter (approx.)


Notice the peak at 5kHz fits the dip in the frequency response...
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Old 17th July 2006, 01:05 PM   #3
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And now the CSD : also taken at 37cm to minimize room interference. I think I still couldn't supress every resonance on the OB, especially in the low end...

But overall quite clean !
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Old 17th July 2006, 01:09 PM   #4
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And finally for the driver measurements itself : the 45 off-axis response. It's quite impressive to see a fullranger that is not so much directive (though it is far from perfect !)
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Old 17th July 2006, 01:18 PM   #5
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now, let's talk about sonics :

I installed the dampened open baffles in front of my usual speakers to see what they are worth.

Dampening is made of clothes, polar wool and floor-cleaning stuff (as you can see )


BTW the cheapo tweeter above the F120A is not used : it is just there because I didn't want to build another OB to measure it
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Old 17th July 2006, 01:26 PM   #6
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A bit of equalisation is needed to compensate for the baffle step and little room interference. (shown is the unequalized response)

I must say I have been surprised to see that Open baffles seem to be less prone to peaks & dips in the bass frequency response than normal speakers. I've been pleased to verify this point that I was a bit sceptical about !

Then, let's play music on them !
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Old 17th July 2006, 01:43 PM   #7
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Compared to the FX120, the sound seems clearer, more transparent with a bit more dynamics and a better impulse response.

Piano sounds even more like a percussion instrument, voices are more natural without being overly bright. Metal instruments are much better spaced and sound true.

Overall, this driver sounds like the FX120 (for those who know it) but in better : it remains sweet and fine, but highs, transcients, imaging and directivity are improved. I have been very impressed by the highs performance that the datasheet wouldn't suggest.

Compared to what I remember from the Supravox 165GMF, I would say it is overall more refined, but with a less punchy and "live" sound. It has less strength in the low-midrange, less power, but it beats it in the upper midrange.


If I had to recommend this driver, I would say no.

Why ?

Because at twice the price of the FX120, it doesn't justify the sound improvement in my opinion.

But if like me, you can get it at half its price, want a shielded driver, or want the ultimate 12cm unit, then the F120A may become your choice.


ENJOY !
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