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
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
Another source with more detailed Lowther driver specs
http://www.n-audio.com/headlines/headers-lowther.htm
http://www.n-audio.com/headlines/headers-lowther.htm
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
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
Attachments
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.
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.
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
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
lowtherdream said:
Hi lowtherdream, have you seen this info?
http://www.quarter-wave.com/Project04/Project04.html
If you go to the General Speaker Related Articles link on my site you will find the measured T/S parameters for my collection of Lowther drivers. If you assume that the A and DX series use the same frame and cone assembly, then you can get some idea of the potential variability in fs, Mms, Vas, Re, and the Q's values.
A good set of T/S parameters is key to designing an enclosure, using computer simulations, that produces an optimum low frequency response. For me, accurately predicting the response during the design phase and then correlating against the measured results is half the fun. But that is just me. There are a lot of ways to design a system with or without the T/S parameters. Lowther drivers are really special in my opinion and they definitely seem to produce a love 'em or hate 'em reaction among users.
Why have you focused on the PM5A driver? What are your expectations/requirements for low frequency performance? How big and complicated are you considering for an enclosure design? There are a lot of options for a Lowther design ranging from simple OB to slightly more complicated ML TL to very complicated BLH enclosures.
A good set of T/S parameters is key to designing an enclosure, using computer simulations, that produces an optimum low frequency response. For me, accurately predicting the response during the design phase and then correlating against the measured results is half the fun. But that is just me. There are a lot of ways to design a system with or without the T/S parameters. Lowther drivers are really special in my opinion and they definitely seem to produce a love 'em or hate 'em reaction among users.
Why have you focused on the PM5A driver? What are your expectations/requirements for low frequency performance? How big and complicated are you considering for an enclosure design? There are a lot of options for a Lowther design ranging from simple OB to slightly more complicated ML TL to very complicated BLH enclosures.
rjbond3rd said:
I browsed thru the site many times but never took the time to read this section. Thanks for the link. My amp is a 6W SET and can't afford to put correction circuitry or extra passive devices in the signal path. I always wanted to try a Zobel but never found the time to test it.
MJK said:
The measured T/S do vary according to your measures. Does it mean I have to build a different cabinet for each driver ? Are the drivers properly matched in the Lowther factory ?
I was planning to go BLH similar to the ones I created for the Fostex FE207E.
The PM5 has great specs and is a very efficient driver. Drivers in the A series is said to be Lowther's most natural sounding drivers.
The PM4A is much bigger and I know that the magnet size will become a problem in certain designs. Since I will probably only buy 1 set of Lowther drivers in my life, I was aiming for what I think is the best unit. Of course, I only had the chance to listen to DX4 drivers, and I doubt I will be able to ever compare the drivers side-by-side in a real live test.
I guess my best option will be to build a decent cabinet using the manufacturer specs, buy the drivers and install them. Once installed, I will be able to burn them in and measure the real specs. With these new numbers, I will be able to design and build a better cabinet, and hopefully be happy with the results
Is there a better approach without spending too much money ?
I have just finished a detailed subjective comparison between the
PM6A, PM5A, and PM4A, all 16 ohm and all Alnico, in my Big Open
Baffles (BOB).
You may recall that they are very similar except for magnet size,
with the PM4 having the most monstrous magnet (It requires a big
butt brace) and the PM6A having the smallest.
All the drivers have comparable response curves in this system, where
they are crossed to a 15 inch woofer at 150 Hz and 12 dB/oct. All have
a mild notch filter at 4.5 KHz, -3db.
The PM5A edges out the other two for upper midrange naturalness,
but the PM4A had the older whizzer design without the rolled edge,
and I speculate that it would have equaled or perhaps bested the
PM5A.
Nevertheless, the PM5A is the one that sits in the system day-to-day.
PM6A, PM5A, and PM4A, all 16 ohm and all Alnico, in my Big Open
Baffles (BOB).
You may recall that they are very similar except for magnet size,
with the PM4 having the most monstrous magnet (It requires a big
butt brace) and the PM6A having the smallest.
All the drivers have comparable response curves in this system, where
they are crossed to a 15 inch woofer at 150 Hz and 12 dB/oct. All have
a mild notch filter at 4.5 KHz, -3db.
The PM5A edges out the other two for upper midrange naturalness,
but the PM4A had the older whizzer design without the rolled edge,
and I speculate that it would have equaled or perhaps bested the
PM5A.
Nevertheless, the PM5A is the one that sits in the system day-to-day.
Lucky man ! You must have easy access to Lowther drivers or dedicate a whole lot of money to audio
If you indeed bought the drivers and only using the PM5A, what is happening to the other drivers
If they are just collecting dust, I can offer a permanent home for them
Thanks for sharing this information and I am glad to ear that the PM5A is a valid option.
Why are you using a BOB and not a BLH ? You probably answered this question before ... but the 2 are at the opposite of the spectrum:
- huge amount of power for the BOB, many drivers, filtering, small footprint ...
- low what for the BLH, single driver, no filtering, generally huge in size.
What is/was driving your choice ?
If you indeed bought the drivers and only using the PM5A, what is happening to the other drivers
If they are just collecting dust, I can offer a permanent home for them
Thanks for sharing this information and I am glad to ear that the PM5A is a valid option.
Why are you using a BOB and not a BLH ? You probably answered this question before ... but the 2 are at the opposite of the spectrum:
- huge amount of power for the BOB, many drivers, filtering, small footprint ...
- low what for the BLH, single driver, no filtering, generally huge in size.
What is/was driving your choice ?
Er, you do know who you're talking to don't you? Nelson owns & runs Pass Labs, one of the most famous high-end amplifier companies in the world. www.passlabs.com He also, as you can see, has put a huge amount back into DIY with his Zen, First Watt & related projects, plus some speakers too, & is a regular contributer here & on his own dedicated section of the forum. So I reckon you can guess why he has a wide selection of drivers...
www.passlabs.com He also, as you can see, has put a huge amount back into DIY with his Zen, First Watt & related projects, plus some speakers too, & is a regular contributer here & on his own dedicated section of the forum. So I reckon you can guess why he has a wide selection of drivers...
Just teasing
I know who Nelson is, but never got the chance to meet him.I am honored that he took the time to share information about the PM5A.
On the other hand, having a company in the audio world does not always equal succes. I have met many with great products, but having difficulty making ends meet. In these difficult economic times, only the large companies will maybe survive and they others will have to keep tweaking their designs in their basement until the economy picks up. Or am I getting this reversed? The sma will survive and the large companies will all collapse ?
I will give up on the free drivers, but the question is still valid ... BOB vs BLH
I know who Nelson is, but never got the chance to meet him.I am honored that he took the time to share information about the PM5A.
On the other hand, having a company in the audio world does not always equal succes. I have met many with great products, but having difficulty making ends meet. In these difficult economic times, only the large companies will maybe survive and they others will have to keep tweaking their designs in their basement until the economy picks up. Or am I getting this reversed? The sma will survive and the large companies will all collapse ?
I will give up on the free drivers, but the question is still valid ... BOB vs BLH
lowtherdream said:
Typically I don't need more than 25 watts for the low end, and I usually
use about 5 watts for the top end.
Two drivers, FR and woofer.
Filtering, simple 12 dB/oct and a simple notch - anyone can do it.
Small footprint.... You got me there, but the BLH's that I like tend to
be on the large side.
Anyways, I like the lack of internal box reflections and the way a dipole
"illuminates" the room.
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