SAL Full Range Drivers

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Hi there,

I think I need to explain why I have been holding back on my measurements. I have design these unit mostly be ear, a lot of measurement has been taken under the design, to confirm what I was hearing. For me, the sound was the most important thing, not how it measured.
I found that there is no standard for how to measure a speaker, other than most measure from 1 meter at the center of the cone. But how many of us is sitting one meter from our speaker?
During measuring my units, I found that the acoustics of the room has a great impact on the curve, also if you move the speaker even slightly the result will also change. One could argue that the units should be measured in a sound proof room (acoustic dead), this will give the best result, but the truth is that most of us have a normal dampened room where we enjoy our music.
To demonstrate the different between measurements on one type of unit, try to compere Nelson and Dick curves, and you see what I mean, I have also posted some of my curves for comparison. Note that they are all different. Note that some of my curves are as standalone others is with a sub.

Frank
 

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Here some pictures of my SAL implementation :D
I have built the baffles myself, had to buy a router (is this the correct name?) to make holes for the drivers. First time I ever worked with such a device, but it was fun:)
Lots of test pieces of wood used, to get the feeling.
The 15" drivers are Faitalpro 15PR400 woofers, which are not that expensive here in Europe.
Before this, I have listened to the FR's without the woofers, but I quickly decided that I needed more bass.
Now the speakers go low and loud enough, still working on the crossover, trial and error.
But, compared to my conventional 3way loudspeakers I'm still missing something in the higher regions, above 8-10Khz I guess.
Strange nobody has mentioned this before here... or is it that obvious with FR?
I think of adding a Super Tweeter crossed above 8KHz.
There are few threads here on DIYAudio which I'm reading now.
Probably a Fostex FT96H or T90A.
Any experiences with that? Tips and tricks?


Walter

Hi Walter,

The units need a break in time of some 50-100 hours, before they start to perform at their best. One other thing I have noted, is the X-over has a big influence on the top end. I ended up with non-textbook X-over in order to get the best performance. Se picture.

Frank
 

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Hi Frank,

Yeah, I´m breaking in slowly, a few hours a day :)

I used the crossover Nelson posted, with a 100uF and 16 Ohm for the SAL unit.
Will try your suggestion for crossover also.
I can hear the drivers are special, so I will invest more time in them.

Thanks everybody
 
Hi there,

I think I need to explain why I have been holding back on my measurements. I have design these unit mostly be ear, a lot of measurement has been taken under the design, to confirm what I was hearing. For me, the sound was the most important thing, not how it measured.
I found that there is no standard for how to measure a speaker, other than most measure from 1 meter at the center of the cone. But how many of us is sitting one meter from our speaker?
During measuring my units, I found that the acoustics of the room has a great impact on the curve, also if you move the speaker even slightly the result will also change. One could argue that the units should be measured in a sound proof room (acoustic dead), this will give the best result, but the truth is that most of us have a normal dampened room where we enjoy our music.
To demonstrate the different between measurements on one type of unit, try to compere Nelson and Dick curves, and you see what I mean, I have also posted some of my curves for comparison. Note that they are all different. Note that some of my curves are as standalone others is with a sub.

Frank

Thanks for sharing this (and sorry for nagging). I think any competent speaker designer will know that the room may have a great effect on the acoustic measurement results (and the perceived sound of a speaker).

That's exactly why I asked for impulse/step response data. Such time-domain data allow gating out room reflections. The anechoic part of the impulse/step response is then very useful to look at the driver (without the room effects). Time-domain data is therefore very useful to understand how a driver performs, and how to design a loudspeaker system using the driver.

Would you share the time-domain data (impulse/step response data)? To be honest, I am in money saving mode in order to come up with a grand to buy a pair of SAL drivers. But it will be difficult to convince myself to actually bite the bullet without access to acoustic measurement data.
 
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...I think I need to explain why I have been holding back on my measurements...

A quick photoshop overlaying the curves and at the same scale to make it easier to see how one has to be very careful interpreting measured curves.

dave

NOTE: 1st & last from above are the same curve
 

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During measuring my units, I found...

Looking at the figures again, I realised the time-domain data shown below the frequency-domain data seems to be noise only (and sometimes some low-frequency oscillation). I can't see any impulse/step response at all. I am not familiar with OmniMic, but it seems a bit like the "frequency response" (upper panel) is just the spectrum of the noise signal (lower panel). What's up with these measurements? Can you share the raw data files of the impulse/step response?
 
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Papa SAL OB photo....so yours is not the same design.
Thanks to Mr Pass
SAL Full Range Drivers

Hi Soundhappy, that's correct, but I did use Nelsons dimensions as a reference. So the same 20" x 40" baffle. The same 5 degree tilt, the same height for the SAL driver.
Only difference is the implementation of the woofer, but that wouldn't impact the very high notes.
 
Only difference is the implementation of the woofer, but that wouldn't impact the very high notes.

Hi WalterW

Woofer and mids-hi full range have different mechanical coupling in your OB. They have bigger tendency to influent each other. Papa design is better.

Separate woofer not at the same piece of wood ( and not mechanicaly coupled ) give probably to SAL drivers more confortable position to give his best frequency response. Is logic what your thoughts ?

Room acoustic and OB position is very important factor and small details
if you put them on the floor with 8 x vibratory absorbers they sound quality and focus can be better.
Other tip : try experiment with solid single core wire small diameter 0.5 mm for téléphone lines or ptt for SAL and coaxial with teflon insulation for the woofer.
Is cheap good quality wire and some times can bring you interesting results.
Greetings :)
 

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Only one wires pair for one driver :)
Your crossover self are ferrite core version, vintage caps ,
inductive and magnetic wire wound resistor ?
Wood spikes are interesting to try
 

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Hi WalterW

Woofer and mids-hi full range have different mechanical coupling in your OB. They have bigger tendency to influent each other. Papa design is better.

Separate woofer not at the same piece of wood ( and not mechanicaly coupled ) give probably to SAL drivers more confortable position to give his best frequency response. Is logic what your thoughts ?

I've tried that in first design, just plain SAL driver without woofer on a open baffle. No crossover that way.
I'm a non-believer in the sound of cables and connectors, especially for such short pieces of 30cm or so.

Walter
 

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We say full range but this is ideal driver with frequency response = 20 Hz to 22kHz.
In reality we get compromise = wide band driver.

Short in low's bass and never expect get super tweeter like performance :D

Without crossover your OB i see have reducted dimension
i know large ones version and is top desirable wood quality.
See on the photo.

Air core is great for crossover but ferrite core is not.

Components precise values and quality is important
and wire as well this is cheap to try not to believe.
You don't try you don't know.
Change all wire for solid core ptt not 30 cm.

Make your experience and research for sound who give you satisfaction.
Again driver vibrations interaction woofer + SAL
and OB direct contact with hard floor and acoustic reverberations.
That from my modest experience.
Have a nice day :)

Air Core Inductor Designer / Calculator

Cable PTT 298 IVOIRE 4P0,5 SE - 14256041 - Electricite
 

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I've tried that in first design, just plain SAL driver without woofer on a open baffle. No crossover that way.
I'm a non-believer in the sound of cables and connectors, especially for such short pieces of 30cm or so.

Walter

Hi Walter,

If you still have your first baffles, you should really try to use an extra unit.
The units need to be fairly equal in parameters, but it is ok to use one with lower fs.
The SAL unit should still run without x-over, the extra unit should be x-over with a 6bD/oct filter somewhere close to baffle respond. This makes a great difference in the low end, given you a better bass respond.
Using the Sal unit without x-over dose limits the SPL at lower frequency’s, but if you can live with this. You will get an output response down to the high 40 to low 50 Hz. This was actually the best configuration I had for acoustic misic.

Frank
 

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If you like I can make a special pair for you:D If you look at the latest picture I posted, you will see that the unit closest to the floor is without wizzer.

Frank


Hi Frank,

Thanks. Looks neat.. Would like to see a measured response one day, and assuming the only change is no whizzer.

BTW, I just read the specs again, that it uses a foam surround. Would that type of foam endure a very hot/humid climate like where I live?
 
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