I don't know Basta, but it looks like a nice comprehensive program. Look for something g called impulse response - the step response is sometimes a subset of that. Changing time delay or phase is used to achieve transient perfect but certain xo topologies such as 2nd order cannot achieve it due to the math/physics. A 2nd order crossover must have one of the drivers in reverse polarity otherwise you get a cancellation dip of "hole" at the crossover frequency. Here is where the B&O "Hole-Filler" xo works, it adds a wideband midrange at the xo frequency to "fill-in" the hole. Mathematically, it can be shown that this technique can yield a transient perfect response. This is actually my current speaker project but is going slow because I don't have a woodworking shop.
Thanks for the info, Wolf. Very interesting - do you have autopsy photos?
I had a cracked frame issue with one of mine which required a replacement as well. They had me send it back though while they sent a new one. This driver when used behind a tractrix horn, has an unbelievable sound that is utterly devoid of distortion, even playing at 110dB. It's dangerous because you can't tell how loud it is based on cues of distortion - it just sounds so clean and pure but you end up with ringing ears.
The spec sheets look like the same driver, just with less smoothing on the 2015 version's FR plot. The first post in this thread predates 2015, and X shows a similar ~10dB spike at 7kHz.
Your efficiency number is close to the ~90dB that I get when I chuck the spec sheet values into a calculator.
But, like this venerable midrange:
...I imagine that, when bandpassed (e.g. 400Hz-4kHz) and listening on-axis, the efficiency you get will be somewhere between the calculated and specified values.
I could take some and post them, as this magnet is too pretty, fun, and strong to get rid of. What happened was during assembly, one NeFeB magnet was impacted by something that made it shatter on the outside. This had to have been before the spider was glued down, because the shards were inside the magnetic gap between the voice coil and the gap. I sent a measurement of the good and the bad unit, and they told me I could keep it. I did try and remove the bits, but they are actually too large to be maneuvered back through the gap and removed. I saw they had a recone kit, and that is why I attempted it. I also used the bad unit's cone for an experiment in the case I thought I'd need to attempt it later.
I'll get them posted soon to show,
Wolf
I did think the same thing about it being smoothed, but the measured T/S are definitely different.
That is generally a 200Hz range output estimate, and in applied use- these will likely be higher than that. I agree with you.
Later,
Wolf
The PRV specs state the cone area went from 80cm^2 to 95cm^2 between 2013 and 2015.
If true: it became a different driver, but they kept the same model number.
If not true: their drivers are being measured differently to how they used to be. Maybe the driver is ~the same.
Based on a small sample (you and X getting defective units, and yours being broken before it left the factory), their quality control doesn't seem great; they musn't be doing any tests on the drivers before shipping them. Unit-to-unit variation could explain the differences in Fs etc.
I got a batch of similar 4" drivers (P.Audio 4") where the unit variation / QC seems to be just as bad. 1 of 4 was a 'dud' - it works perfectly, has the same Fs and FR plot as the other drivers, but it has an undercharged magnet: lower Qes and is -2dB relative to the good ones.
Here's the photos...
You can see the magnet particles NW of the center. The wrinkle due East is self inficted as I was trying to see how thick and far in the copper went. I pried with a screw-driver. Yes- I did slit the cone and apply adhesive black silicone for the damping and sealant- just to see if I could!
Later,
Wolf
You can see the magnet particles NW of the center. The wrinkle due East is self inficted as I was trying to see how thick and far in the copper went. I pried with a screw-driver. Yes- I did slit the cone and apply adhesive black silicone for the damping and sealant- just to see if I could!
Later,
Wolf
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So is this a good driver to continue with for my OB ?
On a related topic, will this be a good driver for the center speaker centered per OB for aesthetics ? I can tolerate the reasonable peaks since that is only for HT but the L + R will be offset to be a smooth as possible per my previous screenshots.
On a related topic, will this be a good driver for the center speaker centered per OB for aesthetics ? I can tolerate the reasonable peaks since that is only for HT but the L + R will be offset to be a smooth as possible per my previous screenshots.
Thanks, Wolf. That's a nice tribute to ScanSpeak. You have in your hands, the world's first PReVelator! 
You might like this thread:
The Daytonator - PA130-8X
Done with a budget PA130-8. I should have used black silicone!
You might like this thread:
The Daytonator - PA130-8X
Done with a budget PA130-8. I should have used black silicone!
I know that this is an older thread but I started experimenting with the tractrix horn and the 5mr450.
I have to say it works quite well.
I did some meausurements but the place is flawed with reflections etc.....So I have to redo it outside when I can.
I did observe some things.
The response goes past 10k but from around 3k it shelves down a bit.
Using a DSP this can easely be fixed but I wanted to try something passive.
If you put A passive hishelf filter before the speaker you can get the response quite flat.
I made a passive hishelf using 15ohm parallelled with 3.3µf and then put this in series with the speaker.(i use the 8ohm version)
It is around 5.6k
It looks like it works and you can use it without DSP
Only downside is that the sensitivity has been lowered to around 100db for 2.83v and the resistor must dissipate some heat.
You wil not easely blow the speaker tough... and it goes very loud...
point source from 200Hz to +/- 15k doing 100db sensitivity and having very low distortion coming from 1 speaker.... I like it.
It can still do 127db max spl but you need to put more power on it beceause of the filter....
I have to say it works quite well.
I did some meausurements but the place is flawed with reflections etc.....So I have to redo it outside when I can.
I did observe some things.
The response goes past 10k but from around 3k it shelves down a bit.
Using a DSP this can easely be fixed but I wanted to try something passive.
If you put A passive hishelf filter before the speaker you can get the response quite flat.
I made a passive hishelf using 15ohm parallelled with 3.3µf and then put this in series with the speaker.(i use the 8ohm version)
It is around 5.6k
It looks like it works and you can use it without DSP
Only downside is that the sensitivity has been lowered to around 100db for 2.83v and the resistor must dissipate some heat.
You wil not easely blow the speaker tough... and it goes very loud...
point source from 200Hz to +/- 15k doing 100db sensitivity and having very low distortion coming from 1 speaker.... I like it.
It can still do 127db max spl but you need to put more power on it beceause of the filter....
Nice trick with the highpass filter to flatten response. I think Kees52 also did this type of thing on a tractrix with FR8. It was amazingly flat - but loss of sensitivity.
100dB is nothing to be ashamed of.
As I recall, 115dB without filter made my ears ring when I did sweeps. Need earplugs to test!
100dB is nothing to be ashamed of.
As I recall, 115dB without filter made my ears ring when I did sweeps. Need earplugs to test!
It certainly gets very loud when testing.
I used an old inkel MA610 power amp for testing (150w @8ohm) and the analog meters on the front nearly moved.
I want to use them for small parties (+/-100 persons). bass+lower mid (+/-60hz to 200hz) will be handled using a 15" folded horn. It will hit hard on the kick and in the chest.
For the sub I am still looking around but the 12pi looks interesting and it can be used in singles
Speaker processor will do the cross over and the alignment (delay). I don't want to mess a lot with EQ. You will get things flat but most of the time it sounds weird when heavely EQ is applied.
Did I mention that I am a big fan of horn speakers?
I used an old inkel MA610 power amp for testing (150w @8ohm) and the analog meters on the front nearly moved.
I want to use them for small parties (+/-100 persons). bass+lower mid (+/-60hz to 200hz) will be handled using a 15" folded horn. It will hit hard on the kick and in the chest.
For the sub I am still looking around but the 12pi looks interesting and it can be used in singles
Speaker processor will do the cross over and the alignment (delay). I don't want to mess a lot with EQ. You will get things flat but most of the time it sounds weird when heavely EQ is applied.
Did I mention that I am a big fan of horn speakers?
hi Vintage Audio Projec - are you using the 4 ohm version? Without the eq/shelving filter, what kind of sensitivity on a horn would you expect for the 8 ohm version? What size is your horn and does it have a back chamber? - I'm looking for alternatives to 1" format phenolic compression drivers - just the diaphragm for a K55V costs the same as a 5MR450.
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Hello XRK971,
I printed out your Tractrix panel plans, thanks for sharing, and noticed that the side panels are not symetrical left and right of the vertical centre line when the centre is taken from either centre of mouth or centre of throat. The centre of the throat is shifted slightly left of the centre of the mouth in the PDF image. I haven not read anything about this in the thread, and was just wondering if there is a reason for this, or if it is due to the 3D model flattening software you used, or possibly Tractrix Horn Calculator? Maybe I have just missed something.
Thanks again for sharing your work so generously.
Regards,
Simon
I printed out your Tractrix panel plans, thanks for sharing, and noticed that the side panels are not symetrical left and right of the vertical centre line when the centre is taken from either centre of mouth or centre of throat. The centre of the throat is shifted slightly left of the centre of the mouth in the PDF image. I haven not read anything about this in the thread, and was just wondering if there is a reason for this, or if it is due to the 3D model flattening software you used, or possibly Tractrix Horn Calculator? Maybe I have just missed something.
Thanks again for sharing your work so generously.
Regards,
Simon
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Hello Fellas! I’m new to this forum and joined due to this post concerning “fast” with the PRV5MR450. With such a beautiful motor assembly I had to pick up a pair. My intentions are to put My vented JBL2235H under or similar efficient woofer, I’m kicking around purchasing a pair of Magnum-12 woofers. Processing and Xover will be handled with either a minidsp ICE amplifier or the 2x4processor. This is My first OB build and with all the research and reading, the whole baffle size and shape doesn’t appear cut and dry, many builds I’ve seen use no baffle at all while others are astronomical! I understand the larger the baffle, the better low extention but is it nessisary in a “fast” configuration? I’m also curious about using a curved baffle and it’s response. Thank You for Your time and experience!
Welcome aboard Jeffrey Ames! If doing FAST with the PRV on top, you don't need to be concerned with size as much to acheive bass as that is handled by woofer. If XO is at say, 500Hz, the baffle could be quite small, and now concentrate more on reducing diffraction. So make it an offset rectangle, a trapezoid, a flower petal, a Fibonacci spiral, etc. They are all better than an equidistant square baffle, or the worst, a round baffle.
Absolutely Fabulous! This makes perfect sense, it’s now time to reach deep into the creative side and make something that looks “WOW”. Thank You! I’m looking forward to posting pics of the finished project.
A quick mock up to see what these sound like before the build. Need something to listen to while fabricating! They sound phenomenal! Currently crossed over at 400hz, TangBand 5-1/4 in a ported Amazon shipping box. VERY excited to put something large under the PRVs. I’d post a pic but no idea how yet.
Modeling up the JBL 2235H to go under the PVR I’m looking at; 4-cu.ft tuned 30hz 2-4” dia. Ports @ 16”
I’m only requesting due to checking My current alignment being off in outer space; Isobaric- 3cu.ft 2-4” ports 14” long... Port tuning is supposed to be 28hz but appears to be ridiculously high. I don’t know if My computer is wacked or if I was when I initially built the thing. I’ve never audibly measured it but always thought it sounded flunky. Thank You for Your assistants in this, I’m currently clueless and second guessing everything. Winisd is showing Me some crazy stuff.
A quick mock up to see what these sound like before the build. Need something to listen to while fabricating! They sound phenomenal! Currently crossed over at 400hz, TangBand 5-1/4 in a ported Amazon shipping box. VERY excited to put something large under the PRVs. I’d post a pic but no idea how yet.
Modeling up the JBL 2235H to go under the PVR I’m looking at; 4-cu.ft tuned 30hz 2-4” dia. Ports @ 16”
I’m only requesting due to checking My current alignment being off in outer space; Isobaric- 3cu.ft 2-4” ports 14” long... Port tuning is supposed to be 28hz but appears to be ridiculously high. I don’t know if My computer is wacked or if I was when I initially built the thing. I’ve never audibly measured it but always thought it sounded flunky. Thank You for Your assistants in this, I’m currently clueless and second guessing everything. Winisd is showing Me some crazy stuff.