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):
Specs:
Does anyone have listening experience with this unit to compare?
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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.
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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.
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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:
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:
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):
Here is the polar response with the Nautaloss at 1 m from 0 deg to 90 deg in 15 deg increments:
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):
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.
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:
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:
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):
Here is the polar response with the Nautaloss at 1 m from 0 deg to 90 deg in 15 deg increments:
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):
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.
Attachments
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.
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.
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.
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.
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.
You mean listen to the same track recorded from both systems? Yes,that is what I think I did (timing was not exact but approx same location in song for Dave Brubeck's "In your own sweet way"). I use headphones to compare - that is the only objective way unless once has a third "reference" system. Since my Nautaloss with sub was already my reference system, I needed an independent way - so headphones.
As I have said before, I feel that the quality of the bass from the SLOB is very good - direct, articulate, not boomy. If I were to build another speaker and made it out of wood, I would make the SLOB with the 5MR450-NDY on top and probably qnty 6 or 8 x 6.5 inch Peerless Nomex woofers on the bottom (or similar). I think it would be tough to beat it for dynamics and realism of presentation.
Okay recorded files compared via headphones.
Myself haven't real experience for OB except for musical instruments guitar/bass, here remember long ago a bass tubeamp Vox 50 watt coubled to 15" OB cabinet was one of the most natural bass sounds i personal ever heard because that setup sounded like a real contra bass. From this experience and what i've read about OB can imagine your description for "dynamics and realism of presentation".
Thanks again spoiling us with your experience, as your new drivers just recently received and taken to use guess you have future non wood plans/ideas.
Myself haven't real experience for OB except for musical instruments guitar/bass, here remember long ago a bass tubeamp Vox 50 watt coubled to 15" OB cabinet was one of the most natural bass sounds i personal ever heard because that setup sounded like a real contra bass. From this experience and what i've read about OB can imagine your description for "dynamics and realism of presentation".
Thanks again spoiling us with your experience, as your new drivers just recently received and taken to use guess you have future non wood plans/ideas.
6MR500NDY-4: 100dB sensitivity fullrange
Here is the bigger brother to the 5MR450, a 6.5 incher with 100 dB efficiency with a pretty good looking response:
http://www.parts-express.com/pedocs/specs/294-2706s.pdf
A 100dB sensitive driver with 250 watt power handling, Qts of 0.41, has ultra-low distortion, and a 100Hz to 13kHz range is pretty cool.
Here is the bigger brother to the 5MR450, a 6.5 incher with 100 dB efficiency with a pretty good looking response:
http://www.parts-express.com/pedocs/specs/294-2706s.pdf
A 100dB sensitive driver with 250 watt power handling, Qts of 0.41, has ultra-low distortion, and a 100Hz to 13kHz range is pretty cool.
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Just for info my program "WinspeakerZ" don't agree the 6 liters sealed box example in post #1, seems some deviation in box volume and SPL.
In program setting Qtc 0.707 gives 1,374 liters verse 6 liters (to get 6 liters mean Qtc setting around 0.604).
In program setting 200 watt as input gives 118dB SPL verse 113dB (needs highpass around 230hZ to keep Xmax safe at low frequency).
Attach picture with plot and known driver parameters (only driver parameter missing seems "Le" voice coil inductance).
In program setting Qtc 0.707 gives 1,374 liters verse 6 liters (to get 6 liters mean Qtc setting around 0.604).
In program setting 200 watt as input gives 118dB SPL verse 113dB (needs highpass around 230hZ to keep Xmax safe at low frequency).
Attach picture with plot and known driver parameters (only driver parameter missing seems "Le" voice coil inductance).
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I only used 6 liters because that is close to the size of the box I had and one can control Qtc directly in AkAbak by setting it independent of volume. In reality this can be done by adjusting level of stuffing. Having much smaller 1.37 liter volume will of course allow higher SPL but will give a very congested boxy sound as all that back energy radiated can come back out the cone much easier. Let me rerun the sim in AkAbak with 1.64 liter and Q of 0.64 and same HPF and see what I get. I don't think there is disagreement just that we used different volumes and Q.
Probably answer. This program either set box volume or Qtc and the other setting arrange itself, and default setting is 0% for stuffing. Later % of stuffing can be set which then changes box volume.
that does look like a good 6" speaker - wonder how it would do with a rear load K-tube per Silvercore?
PRV AUDIO 6MR500-NDY-4
my whizzerless FE164 rear loaded - no damping in tube
PRV AUDIO 6MR500-NDY-4
my whizzerless FE164 rear loaded - no damping in tube
An externally hosted image should be here but it was not working when we last tested it.
Freddi,
The open back K tube idea is pretty neat - sort of like my Nautaloss in not giving coloration from the box by preventing back reflections and resonances. It will have a back wave and be semi-dipole like an OB though. That PRV 6 inch or 5 in her would probably don pretty well. In your setup, where are you running the XO to the lower bass unit? In the 350 to 400 Hz range?
The open back K tube idea is pretty neat - sort of like my Nautaloss in not giving coloration from the box by preventing back reflections and resonances. It will have a back wave and be semi-dipole like an OB though. That PRV 6 inch or 5 in her would probably don pretty well. In your setup, where are you running the XO to the lower bass unit? In the 350 to 400 Hz range?
Using a tractrix profile calculated using Volvotreter's spreadsheet with 2 curved walls and 2 flat walls (http://volvotreter.de/downloads/Tractrix_v1.4b.zip), then modeled in Akabak as a 16 segment waveguide I get the following response for a 0.67m wide x 0.45 high x 0.54 m long tractrix horn with a 7.1 cm square throat. It provides a speaker with about 109 dB sensitivity at 2.83v and 1m, and a 130 dB SPL at 1m and 37 volts when driven to xmax - which also corresponds to 225 watts rms max thermally limted power rating. This is with a sealed 6 liter heavily stuffed rear chamber.
This speaker is very sensitive so cone motions at 100dB SPL at 1m are in the 50 micron range, and as a result, HD is very very low. I would guess consistently below -60dB THD.
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I didn't play much with that 10" rubber surround Pioneer woofer and the K-tube/FE164 - the woofer was incapable of playing Dan Weiss "Tintal" CD which used a full western drumkit instead of the traditional Indian tabla pair and a Stratocaster instead of a harmonium - that's a fun album and will weed out speakers which can play vs those which can't. Suggestions of "1st order networks" aren't good either as the fullrange must play with low excursions.
this little 6" Faital should be cool on a midhorn - the only one I have somewhere is a cutdown 150Hz made by Bruce Edgar
Faital has an 8" with "phase plug" and 1.5" coil that looks ok - Crunch makes similar in both 4 and 8 ohm versions with a stamped frame which plays pretty smooth and used to sell for between 20 and 30 dollars http://www.amazon.com/Crunch-CRSS8-Full-Range-Screamers/dp/B003INRH1Q
Alpha 6 in front load K-tube and on a 150Hz horn (no back chamber) - the horn was sitting on the ground as pictured IIRC and the
tube leaned forwards for around 30 degrees elevation from horizontal.
this little 6" Faital should be cool on a midhorn - the only one I have somewhere is a cutdown 150Hz made by Bruce Edgar
Faital has an 8" with "phase plug" and 1.5" coil that looks ok - Crunch makes similar in both 4 and 8 ohm versions with a stamped frame which plays pretty smooth and used to sell for between 20 and 30 dollars http://www.amazon.com/Crunch-CRSS8-Full-Range-Screamers/dp/B003INRH1Q
Alpha 6 in front load K-tube and on a 150Hz horn (no back chamber) - the horn was sitting on the ground as pictured IIRC and the
tube leaned forwards for around 30 degrees elevation from horizontal.
An externally hosted image should be here but it was not working when we last tested it.
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