PRV 5MR450-NDY for FAST/WAW applications

[xrk971]

IIRC, it was 110dB to 115dB in a tractrix with a 30in wide mouth. A simple 1st order high pass set a little higher than the peak hump will probably equalize everything flat to 108dB or so.

 

[freddi]

that would be just about perfect. I may be getting some Audax mids just for sihpping and assume from the description (had foam surround but replaced with cloth) might be PR170 (?) - they just need new dustcaps and may work ok on the right horn

if so then:

don't think it will be loud enough on a horn

An externally hosted image should be here but it was not working when we last tested it.

 

[hollowboy]

IIRC, it was 110dB to 115dB in a tractrix

The numbers you state are higher than for an equivalent compression driver.

e.g. B&C DCM50 2" Neodymium Midrange Compression Driver is almost four times the price and 'only' 108.5dB.

e.g. JBL 2445 is a ridiculous 14kg hunk of metal, and 'only' achieves 111dB


Questions:


(1) I've A:B compared several cone drivers on the same horn as a JBL 2445 (111dB) and none was quite as loud as the JBL.

Have you ever done a similar comparison as a reality check?

(2) If your numbers are right, they should be ubiquitous in PA equipment / professional use.

That is: why would a professional choose the B&C DCM50 (or similar) if a PRV driver would be 5dB more sensitive AND have triple the power handling AND cost much less?

 

[Vintage Audio Projec]

Those numbers are indeed high.

But I have to say. I also made the wide tractrix horn and it seems t work very good.
I used them for a party some time ago with a 150w amplifier and the signal meters where barely moving.
I had around 20db of headroom
I used some 15" folded horn using the 15p80fe from beyma underneath it and it didn't reached the very low notes but sounded very powerfull and punchy.
The folded horn was powered with around 1600w I think and I also had around 20db of headroom so to keep up with this tractrix horn you really need something.
I still need to make some pictures and do some more testing but time.....

Just to say maybe the numbers are a little bit to high but it does work very nice.

 

[xrk971]

I might be off by 5dB, I think 105dB to 110dB. I know that a properly designed tractrix adds 10dB. If you start at 95dB it’s not hard to get 105dB. There is a 5dB (15dB total) overshoot at the low corner. I might have to retake the data again as my data was lost in a HD crash a while back. I do recall my ears ringing from sweeps since I did not wear earplugs.

Why pros don’t use this? Tradition I suppose - people seem to think a CD is louder. The PRV is very stiff in suspension and has a massive Nd magnet assembly. Putting it on a 30in wide tractrix isn’t something other people have really tried on this driver. In a way, you can think of this as a very large compression driver that can take 225w thermal. It could use a phase plug to get rid of those dips.

 

[hollowboy]

to keep up with this tractrix horn you really need something.
[...]Just to say maybe the numbers are a little bit to high but it does work very nice.

My experience is in keeping with that. My living room rig is currently mono, using a horn loaded 2" fullranger with 4x15" in sealed boxes (2 for midbass, 2 used as subs).

The subs need more power than the 2".

...hence I decided to put my JBL drivers up for sale. Their output is overkill for any system I can fit in my house (the LF will always be a weaker link), they weigh literally 100 times as much as the 2" driver I'm using ...and I simply have too much stuff.

If you start at 95dB it’s not hard to get 105dB.

That number seems about right to me - massive by home HiFi standards, but a bit below the loudest of compression drivers.

It could use a phase plug to get rid of those dips.

Sorry if you've already seen me mention this, but it seems that using a non symmetric throat works quite well for removing dips*.

e.g. use a 3:2 rectangle throat (rather than square), and ~randomly place a few big blobs of felt to partially fill the gap between the cone and mounting surface.

* the mention of phase plugs reminds me: I got several Scanspeak 15M/4624G for exactly this reason, but shipping delays were so huge that I'd moved on to another project by the time they arrived! I still haven't tried them on a horn. I should dust them off soon

 

[Bigun]

I think it's worth listening to the 5MR450 driver, naked if needed, first to see if that peak in the treble is acceptable. For me it would be a no go but my ears are fussy that way.

 

[Vintage Audio Projec]

it is maybe a weird and stupid idea but wouldn't it be possible to mount a compression driver on the magnet of the 5mr450 like a coaxial driver is build.

 

[xrk971]

You might get something like this

B&C 5FCX44 5" Professional Coaxial Speaker 70 x 70 8 Ohm

Or this

B&C 6HCX51 6.5" Professional Neodymium Coaxial Speaker 70 x 70 8 Ohm

 

[Jeffry Ames]

I’m having trouble mocking up My passive radiator alignment in ISD.
I’m not sure why it’s not excepting it, it has no issue computing as ported.
Could one of You take a peek?
I’m using the JBL2235h
4 cubic feet net “driver and PR volume already removed”
18” Dayton PR;
Specifications: • Fs: 14.7 Hz • Vas: 15.86 cu. ft. (449.0 liters) • Qms: 5.03 • Cms: 0.23 mm/N • Mms: 500g • Rms: 9.21 kg/s • Sd: 1164 sq. cm. • Xmech: 34 mm • Dimensions: Overall diameter: 18.17", Cutout diameter: 16.69", Depth: 6.18".
I don’t know if the cones initial weight is too heavy or if there is some glitch in ISD
Thank You very much!
I’m new with passive radiators and it could be user error.
This is My intended bottom for My FAST system using the PRV 5MR450s

 

[oohms]

The faital 15PR400 in a 220L ported cabinet is a perfect match for the 5MR450 (without a horn) - same sensitivity, and flat to 30hz in the room

Maybe i should redo those recordings - the bass is much better now

 

[Vintage Audio Projec]

You might get something like this

B&C 5FCX44 5" Professional Coaxial Speaker 70 x 70 8 Ohm

Or this

B&C 6HCX51 6.5" Professional Neodymium Coaxial Speaker 70 x 70 8 Ohm

Would be nice to find something that has the same power handeling as the PRV

I was actually looking at some BMS coaxial drivers that would probably work quite good.
Point Sources

One day I should try one of those triaxial drivers......

 

[hollowboy]

Would be nice to find something that has the same power handeling as the PRV

When comparing drivers with similar tech + materials, you'd expect the power handling to scale roughly with voice coil size.

The PRV driver has a 1.5" VC.
...spec sheet says "Rated Power Handling: 225 Watts".

The B&C 6.5" coaxial has a 2" voice coil diameter.
...spec sheet says "LF nominal power handling: 150 watts"

So why is the PRV number higher?

PRV: 290Hz crossover "for full power handling"

B&C: 89Hz crossover*. A much more robust test.

*2 hours test made with continuous pink noise signal within the range Fs-10Fs. Power calculated on rated nominal impedance. Loudspeaker in free air.

...not that it matters in most applications. That's a free air test. That many continuous watts in a small enclosure = a miniature oven. It would eventually ignite the cabinet, even if the driver was impervious.

 

[Defo]

The official frequency response graph looks quite different to the one posted here, and the unofficial ones. Which are correct?

 

[BYRTT]

In this one they overlaid and X/Y ratios close to that of post 374 but extending Y scale to a lower dB reach in comfort for the other ones, green is xrk971 curve from post 1, red is factory from post 1, and brown is factory from post 374.

 

[Bigun]

You might get something like this

B&C 5FCX44 5" Professional Coaxial Speaker 70 x 70 8 Ohm

Or this

B&C 6HCX51 6.5" Professional Neodymium Coaxial Speaker 70 x 70 8 Ohm

For Canadians I recommend this reseller: B&C Speakers Canada - Largest Inventory in Canada - Same Day Shipping*

 

[freddi]

it took me about a minute for magic smoke to come out of an Eminence 151269 15" woofer and 3" VC in a tight sealed cabinet (limiting cooling excursion) with maybe 120W LF sine A 15 watt soldering pencil can get pretty warm to the touch.

 

[Berd]

Petal JMLC Horn for 5MR450

XrK:

Thanks for another great thread.
I'm putting the 5MR450 on a short list for my next project.

I'm thinking of (4) Peerless SLS 12" drivers per side in a SLOB with the PRV in an open baffle on top.
The sensitivity of the Peerless is a bit low at 89.8 but I am hopeful using 4 of them will be enough.
Any thoughts on this configuration ?
BTW: I already have a Mini-DSP 2x4 HD and a pair of amps so the crossover and level matching should be relatively easy.

Peerless by Tymphany 830669 12" Paper Cone SLS Subwoofer

Also, In one of your posts you mentioned you did not have a wood shop so had do do things with flat stock.
You seem to be the master of foam/card board construction and it is great to see what can be done with these basic materials.

I recalled a thread on JMLC "petal" horns using flat card stock.

Paper Horn constuction

I have not tried it but apparently Hornresp can do up to a 20 petal horn and give you the flat stock template.
I know you kind of gave up on the tractrix but perhaps the round throat of a petal horn might work better.

Thanks again for the great work!

 

[xrk971]

Four 12 SLS woofers in a SLOB would be very good as you would have 96dB of sensitivity and a perfect match for PRV without baffle step. A SLOB is a dipole so I am not sure if that has -5dB baffle step falloff like traditional bass reflex or sealed box.

I haven’t given up on tractrix - just using my FAST most of the time since it doesn’t require an active crossover. Although, I now have 8 channels of state of the art Class A amps and could do a 2x8 miniDSP active Class A system of I wanted to.

The Trynergy is still one of the top 3 speakers I have ever heard. I still very much like tractrix front loaded horns.

 

[gazzamongoworld]

Any known suppliers in uk/europe for this driver? Prv don't bother replying on their fb page :s