Lowther PM5 specs

[lowtherdream]

I am planning to build a non-folded BLH using the Lowther PM5 drivers. The specs are minimal on the Lowther site and I asked for more details. Just got more detailed specs about the Lowther PM5 driver, thanks to their technical department. I will also send the specs to Dominique Petoin and the Thiele-Small database.

Brand Lowther
Model PM5
Description High end full range coaxial HiFi, available in 8 or 15 ohm. Twin Paper cones.
Range / type Full range
Recomended enclosure : The Medallion is very popular amongst audiophiles building their own enclosure
Series A
Nom. diamerer [inch] 9
Vas [Liters] 42.102
Qts 0.267
Qes 0.327
Qms 1.477
Fs [Hz] 36
Sensitivity [dB] 98
Max Power [W] 100
Lower freq [Hz] 30
Upper freq [Hz] 20000
xmax [mm] +- 1
Moving mass [g] 8.75g
Disp area [m2] = See below
Air gap [mm] 1mm
Coil height [mm] 5mm
Coil diameter [mm] 39
Cms [mm/N] 672.322 uM/N
Magnet weight [gr] 5kg
Magnet height [mm] = 86 mm ( inc steelwork)
Magnet diameter [mm] = 115 mm
Magnet material - Alcomax 3
Re [ohm] = 7.4
Z [ohm] = See below
L [mH] = See below
Bl [Tm] 9.04
Flux density [T] 2,3
Outer diam. [mm] 232
Bolt circle [mm] 208
Nr of bolts [Nr] 3
Cutout [mm] 190
Weight [Kg] 6,5
Height [mm] = 110 mm from back of frame
Depth [mm] 124
Driver volume [Liters] = 0.72 Ltrs
Disp Area: Assuming that piston area is required, which is 21.000m M2
Z: Assuming ZMax is required, which is 40.86 Ohms
L is measured in meters not mH as requested. L would be 5.68 meters

Just sharing info

[lowtherdream]

Another source with more detailed Lowther driver specs

http://www.n-audio.com/headlines/headers-lowther.htm

[rjbond3rd]

Hi Lowtherdream, tell us more about this non-folded BLH design!

[lowtherdream]

Something like this ...

This is my first attempt using Fostex FE207E drivers. They sound very good, even compared to what I usually ear at audio shows. Definitely not the best ... but I am working to improve it. No special tweaking of the drivers, nothing fancy in the compression chamber except Deflex on the back wall.
I am not too happy with the craftsmanship. I made a lot of mistakes and the 2 horns are not 100% symmetric (maybe 95%).
It was a great learning experience and a required step before playing with delicate Lowther drivers.

I have used examples on the Dominique Petoin site to design the horns to match with the Fostex FE207E driver.

http://www.petoindominique.fr/php/pavar.php

[MJK]

I don't believe the specs provided for the PM5. I don't believe any of the specs shown on the link. I strongly recommend measuring any Lowther drivers that you buy to get accurate specs before designing an enclosure.

[Scottmoose]

Amen. Those don't match the average specs I have, and given that they're hand-built, sample variability on Lowthers is quite high.

BTW -technically, that's still a folded horn. Unfolded really means no folds, turns or bends, i.e. straight. Not that the results are likely to be significantly different in practice, looking at it. And BLHs don't really have compression chambers, other than the room it happens to be situated in. OK, yes, I'm nit picking... We know what you mean.

[AndrewT]

is the PM5 BL really as low as 9?

[Scottmoose]

Yep. Although that'll doubtless vary driver to driver.

[lowtherdream]

Thanks, MJK ands Scottmoose, for your input. So the 1st step is to really buy the drivers ? How much do they drift from specs and how well matched are they when shipped from the factory ?

I hate the fact that I will have the drivers on a shelf until the cabinets are ready. Last time, it took 8 months to build them

Which one of the parameters will cause the the design not to work properly ?

Normally, I take these values to design the profile of the horn.
Fs, VAS, Qes, Qts, Re, BL and Sd.
Fs is probably OK
VAS should not change
Re can vary and affect Qes
Qes will impact Qts
BL can vary and impact Qes also
Am I missing other possible important variables ?
How many companies design cabs for a specific set of drivers ? How many DIYers go to that extent ? And does it really make an audible difference, or is it just nice on paper ?

Obviously, I am still a newbie and more of a technician then and engineer. I like to try to build things, try to better understand them as I make mistakes

Can you elaborate on your suggestion and possibly help me make sense of all this? Because of the not so bad results with the first speakers, I was expecting to be lucky a second time

[rjbond3rd]

Originally posted by lowtherdream
So the 1st step is to really buy the drivers ? How much do they drift from specs and how well matched are they when shipped from the factory ?

Hi lowtherdream, have you seen this info?

http://www.quarter-wave.com/Project04/Project04.html