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PRV 5MR450-NDY for FAST/WAW applications
PRV 5MR450-NDY for FAST/WAW applications
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Old 21st July 2014, 05:20 PM   #21
xrk971 is online now xrk971  United States
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PRV 5MR450-NDY for FAST/WAW applications
Click the image to open in full size.

Perhaps the closest driver from Fostex is the FX120 which is almost a 5 incher with 2 mm xmax and similar Qts to the 4-ohm 5MR450 but reaches much lower with fs of 70 Hz and only 89 dB of sensitivity and 30 watts max power (which I think is good for 104 dB max SPL). It has a pretty flat frequency response (but not quite as good as 5MR450 off axis):

Click the image to open in full size.

Specs:
Click the image to open in full size.

Does anyone have listening experience with this unit to compare?

Last edited by xrk971; 21st July 2014 at 05:25 PM.
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Old 22nd July 2014, 09:25 AM   #22
anthonybisset is offline anthonybisset  Japan
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Heya X,
To be fair wouldn't measuring on an open baffle make the polar response a lot more even? I'm doubtful the Fostex was measured OB, probably more likely in a sealed or reflex enclosure (or did I miss something)?
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Old 22nd July 2014, 09:36 AM   #23
xrk971 is online now xrk971  United States
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PRV 5MR450-NDY for FAST/WAW applications
Quote:
Originally Posted by anthonybisset View Post
Heya X,
To be fair wouldn't measuring on an open baffle make the polar response a lot more even? I'm doubtful the Fostex was measured OB, probably more likely in a sealed or reflex enclosure (or did I miss something)?
Most speaker freq response measurement plots are measures using an IEC "open baffle" unless otherwise stated. At least that is the assumption.

Here is the standard baffle for drivers under 8 in dia.

IEC 268-5 Baffle :
1350 mm x 1650 mm (h, v)
150 mm x 225 mm offset (h, v)

Polars on a narrower (12 in wide) OB will be better in lower freq range but variation above 8khz is really function of shape of dust cap and cone ( whizzers if used, surround, bezel, etc).

Next experiment may be to shoehorn the 5MR450 into my existing Nautaloss enclosure designed for the TC9FD. The width is just barely wide enough and some surgical removal of the first internal brace may be required. But this may give me close to an infinite baffle response and much better polars.

Last edited by xrk971; 22nd July 2014 at 09:42 AM.
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Old 22nd July 2014, 09:48 AM   #24
anthonybisset is offline anthonybisset  Japan
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So I was missing a something, thanks for bringing me up to speed.

Interesting that the PRV 5" has a more even off axis response than a 'comparable' 4".
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Old 22nd July 2014, 09:55 AM   #25
xrk971 is online now xrk971  United States
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PRV 5MR450-NDY for FAST/WAW applications
Quote:
Originally Posted by anthonybisset View Post
So I was missing a something, thanks for bringing me up to speed.

Interesting that the PRV 5" has a more even off axis response than a 'comparable' 4".
My theory is that the dome dust cap and cone/surround shape are key. The highly dished - near hemispherical dome shaped dust cap acts as the HF dome tweeter. The cone acts as the waveguide. The "W" shaped cloth surround is low profile and has less diffraction than the U shaped rubber or foam single roll surround. The hyperbolic or exponential curved shaped of the cone as a waveguide is better than a shallower linear expansion cone.

So look at a good dome tweeter with built in waveguide and notice the similarities?

So I think flatter dust caps or sans dome dust caps will not be as good. Not sure about nicely machined bullet phase plugs but my hunch is that they are not a radiator and not as good.

Last edited by xrk971; 22nd July 2014 at 09:58 AM.
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Old 24th July 2014, 05:57 AM   #26
xrk971 is online now xrk971  United States
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PRV 5MR450-NDY for FAST/WAW applications
Default 5MR450-NDY stuffed into a TC9FD's Nautaloss

I wanted to see what a sealed cabinet would look like with this driver so I shoe-horned it into my existing Nautaloss spiral sealed TL enclosure that normally houses a much smaller Vifa TC9FD. I had to add a third layer of foam core on the baffle for extra strength, I removed some bracing with a razor, and added more closed cell foam and stuffing behind the driver. Here is a photo of the oversized driver sitting in a tiny Nautaloss:

PRV 5MR450-NDY for FAST/WAW applications-5mr450ndy-nautaloss-jpg

I think the Vifa's Nautaloss is too small for this driver as you will see that there appears to be coloration in that the response is not flat anymore. Listening to it in the Nautaloss, it sounded a bit bright and that is probably due to the rise between 1-2kHz. Here is the frequency response and HD at 0 deg, 1 meter away, 2.83 volts drive voltage:

PRV 5MR450-NDY for FAST/WAW applications-thd-0deg-nautaloss-5mr450ndy-1m-2-83v-stuffing-png

Note that the HD with the sealed Nautaloss enclosure is very low, lower than it was in the OB configuration. Just to demonstrate how low the HD is and how clean this signal is, here is the RTA with a 2kHz sine wave drive at 2.83V (the HD is more than -60 dB below the fundamental, and the fundamental is a very sharp peak - which explains why this driver sounds so good as it is very clean):

PRV 5MR450-NDY for FAST/WAW applications-rta-2000hz-2-83v-thd-png

Here is the polar response with the Nautaloss at 1 m from 0 deg to 90 deg in 15 deg increments:

PRV 5MR450-NDY for FAST/WAW applications-polar-nautaloss-5mr450ndy-1m-2-83v-png

Here is the comparison of the Nautaloss and a larger OB (22 in wide x 35 in high, driver offset so that it is 9 in from side and 9.5 in from top):

PRV 5MR450-NDY for FAST/WAW applications-nautaloss-ob-fr-1m-2-83v-compare-png

The OB is clearly flatter which means that the Nautaloss is too small to act as an acoustic black hole. I think the Nautaloss can work with this driver, it just needs to be designed from scratch and made bigger.
Attached Images
File Type: jpg 5MR450NDY-Nautaloss.jpg (88.1 KB, 2240 views)
File Type: png thd-0deg-nautaloss-5mr450ndy-1m-2.83v-more-stuffing.png (124.3 KB, 2604 views)
File Type: png rta-2000hz-2.83v-thd.png (90.8 KB, 3123 views)
File Type: png polar-nautaloss-5mr450ndy-1m-2.83v.png (128.8 KB, 1773 views)
File Type: png nautaloss-ob-fr-1m-2.83v-compare.png (95.6 KB, 2242 views)
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Old 26th July 2014, 01:40 AM   #27
xrk971 is online now xrk971  United States
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PRV 5MR450-NDY for FAST/WAW applications
Default 5MR450-NDY stuffed into a TC9FD's Nautaloss - Sound Clips

I am running this new driver in the undersized Nautaloss I cabinet connected to the identical rig used for the Nautaloss II's with a sub both driven by a miniDSP and bi-amped with vertically integrated TPA3116D2 (Ybdz 2.0) amps. I am using the same miniDSP XO and EQ settings (175 Hz 24dB BW and BSC). That is, touching nothing else other than to swap out the speaker and disconnect the right channel, to run in mono on the left channel, it sounds just as loud as the stereo Nautaloss II's (owing to the 5MR450-NDY's 95 dB sensitivity vs 94 dB for the stereo pair).

Spending some time listening to different types of music and the biggest thing that strikes me is that the highs on the 5 inch PRV seem more clear than the 3.5 in Vifa - the distortion is in the -60 dB range and there is more air and sparkle. The complex piano passages seem less congested. Most of all, there is more visceral impact that a larger driver has - nothing beats square inches I guess.

I am very impressed with the dynamics that this driver has - just gobs of headroom available and you can turn it up and up and it doesn't distort. Clear as a bell at full volume (about 17 volts rms). Value wise, the TC9FD is still the king, but this driver has the ability to be pushed and not complain, and more than that, it has some additional sparkle and punch.

Here are some sound clips that demonstrate what I am talking about. The first one is the same passage that was the second clip with the SLOB. The other two are some vocals.
Attached Files
File Type: zip 5MR450NDY-Nautaloss-Clip-01.zip (790.9 KB, 91 views)
File Type: zip 5MR450NDY-Nautaloss-Clip-02.zip (747.0 KB, 70 views)
File Type: zip 5MR450NDY-Nautaloss-Clip-03.zip (754.7 KB, 58 views)
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Old 26th July 2014, 03:29 PM   #28
BYRTT is offline BYRTT  Denmark
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PRV 5MR450-NDY for FAST/WAW applications
Many thanks xrk971 for sharing and posting so much information.

When listening 5MR450NDY-SLOB-Clip-01.mp3 verse 5MR450NDY-Nautaloss-Clip-01.mp3 i can't hear much bass weigtning difference as expected as the Nautalos has bass/sub support (Listening system small cheaper Edirol MA-5A monitor (BR Fullranger) connected desktop via USB sounddevice).

Am i too lazy tonight and need to play files at system with more bass support or headphones or could it be drivers combined phase domain errors at XO region relative to microphone position that i think Nautaloss file lacks bass.

About PRV 5MR450-NDY wonder why no spec for voice coil inductance (Le) is reported at datasheet.
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Old 26th July 2014, 03:56 PM   #29
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Quote:
Am i too lazy tonight and need to play files at system with more bass support or headphones or could it be drivers combined phase domain errors at XO region relative to microphone position that i think Nautaloss file lacks bass.
The bass from the SLOB is more direct as it was measured 1m away from qnty 6 x 6.5 in drivers. The bass on the Nautaloss is provided indirectly with a single corner loaded sub that uses qnty 4 x 5 in drivers. The extension on the SLOB is probably deeper and more direct but the distortion on the Nautaloss sub is lower distortion I think.
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Old 26th July 2014, 04:17 PM   #30
BYRTT is offline BYRTT  Denmark
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PRV 5MR450-NDY for FAST/WAW applications
Thanks direct/indirect probably a good answer (think indirect give position dependant phase domain errors for the FAST system). Have you tried comparing same two tracks replayed at same system to hear difference seen from microphone point.
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