SAL Full Range Drivers

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Thank you for the feedback, scottjoplin. I will do things the right way. I will install the drivers to the flat plywood panel and report back what my impression about the drivers.

Regards,
Tom
If the driver is lying flat on the desktop you'd have been getting a lot of very early reflections, you really can't tell what it sounds like in that situation
 
A few updates
- Ideas: inspiration from PureAudioProjects and laverda. I used 2 Eminence 15 Beta and SAL driver for OB model
- Xover: Using Frank's passive model

I finished 1 set of OB and have an audition last night. The sound is not what I was expecting it to be. The sound is very thin, imaging and soundstage is collapsing. There is a little bit bass but not much. The sound is not airy and open, it sounds like there's a big curtain or a wall in front of the drivers.

I even used a U frame model and pull the speaker 1 or 2 meter away from the wall but the sound is not improving.

This is the 1st time that my DIY experience is somewhat discouraging and not what I expected to be after so much effort, time and money spent. However, I will continue to try different thing if there is any to really improve sound much further. I know and I can feel it's almost there just a little bit of push to get there :)

I have a few things that I'm thinking to try
- getting a miniDSP UMIK-1 Omni-directional to measure out the frequency response of the OB driver
- Trying out Nelson's passive Xover to see if it makes any difference
- Remove the 2 wings
- Last: trying out active crossover and bi-amping. I was hoping to get good result with passive Xover first to use it as a reference before going to active Xover

If you have ideas or suggestions, please let me know.
Appreciate the inputs as always.
Best,
Tom

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[/url]My_OB03 [/IMG]

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[/url]My_OB01 [/IMG]

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[/url]My_OB02[/IMG]
 
The 45 bit makes sense for even great relief, especially if there's enough thickness left to securely attach the driver.


I scrolled through the thread and noted that the none (?) of the examples used a backside relief. Some also mounted the driver inset and flush with the baffle, and some simply attached it to the baffle. What are the best practices here? I usually do both.


I'm not building this speaker, at least not yet, just curious...


BK
 
frugal-phile™
Joined 2001
Paid Member
If you are not using MDF securing the driver should not be an issue, and if it concerns you just leave an areas around the scres un-rebated.

Drivers should be relieved and ideally rebated flush with the baffle. Some drivers have shallow bezels and it makes little difference, but even with those a rebate makes things look better.

dave
 
If you are not using MDF securing the driver should not be an issue, and if it concerns you just leave an areas around the scres un-rebated.

Drivers should be relieved and ideally rebated flush with the baffle. Some drivers have shallow bezels and it makes little difference, but even with those a rebate makes things look better.

dave

hi Dave,

Besides SAL back baffle 45 degree cutout relief, is there anything else that you know or think of that can further improve the sound ?

As you can see in the picture, I do not have alot of room to further cut out since the screw to attach the SAL driver to the 3/4 in thick plywood is already too closed to the edge of the cutout circle.

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Thanks,
Tom
 
frugal-phile™
Joined 2001
Paid Member
Looks like a fair bit of room to me, but if you are concerned only ream out the space between the bolts.

Other things to watch for are cranked the bolts/screws down too much, there should only be sufficient torque to stop a real or imaginary washer from turning.

Biamping would also be suggested… i don’t know whether you could get away with a PLLXO.

I have experience with the 15 Alpha, i don’t know how much improvement the beta provides, but the Alpha would not be up to the quality needed to keep up with the SAL. Even with some standard mods.

I would also seal up the leak between your baffles. Some draft exclusion tape (weather seal) should do it.

dave
 
I must first confess that as an old school TL guy the OB thing looks just plain wrong. That baffle has to be wiggling when the woofers, especially the upper one, are doing what they can to make bass even though the configuration is erasing most of the low frequencies. Would you consider moving the SAL to the top and adding a brace from there to the floor? I look at everything through a carpenter's eye, btw.
 
Phivates and Planet10,
Thanks for the feedback, first off, I'm only the beginner in this field, and OB idea seems so appealing to me. After watching so many builders design, I ended up with this design and thought to have good results. You can look back this thread on page 7-11 and a few members are actually using the exact same design with 3 separate pieces with SAL in the middle and 2 sub on top and bottom.
Also pureaudio projects is using this model
Trio15 Product Line, Open Baffle Speakers – PureAudioProject

Anyway, the fact that many people do it does not justify the sound that I heard. My ears cannot lie that the sound is not right. I can try to bring SAL to the top and put 2 sub below if it makes a difference.

Can you clarify more about " adding a brace from there to the floor" ?
 
I want to see a triangulated brace, maybe in the form of a tapered side wing, which lands at the floor at least a foot behind the front of the baffle. Or 16" - I'm a carpenter and that is a basic dimension in what we do. Having the SAL mounted to a baffle that is in motion can't be good for the precise rendition of musical detail in my opinion...which is all I have to offer.
Actually what I really want to see is the woofers in sealed boxes but again, JMO.
 
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Hi tommy, sorry to hear things aren't working out. Are you using any EQ on the woofers? On an open baffle like that they going to need quite a bit. It's not something I like the idea of. They'd be better off in an H or U frame. How deep was the U frame you tried, and did it have a top as well?
 
frugal-phile™
Joined 2001
Paid Member
- Xover: Using Frank's passive model

I see the map in post #82, but it is not clear what woofers the XO is for. If they are not the same as yours, you may be able to get a starting point from the hi-pass but it will need developing from scratch (unless someone in the thread has already successfully built this arrangement.

a note from one of Frank’s post:

I have always had a challenge with x-over’s, there is a lot of factors that must be taking in consideration and it takes a lot of work to get it right. I find that even a small change can have a huge impact, but after many hours of experimenting I got the result that I was looking for.

dave
 
hi scottjoplin and planet 10,

The U frame side wing is 4 inch deep and 48 inch tall. It's about the depth of the sub. I'm not using any EQ for the bass. No top cover

I think I will go with active Xover this time. I will DIY B4 or B5 using all n jfet in stead of wasting money to buy all the L,C,R component for passive Xover and get lost in the jungle.

I'm thinking of starting from scratch by getting a large piece of plywood 4ft x 4ft and mount only SAL driver in the middle with some cutout in the back as per your suggestion. Using no crossover, directly connect the SAL driver to my FW class A amp see how it sounds before adding in the Sub.

Tom
 
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I think for the subs you should consider something like this Dipole protos or a U frame with a similar depth, you need at least 12 inches I would say. Also if they're in a separate cabinet to the SAL driver they could be placed against the side walls, if possible in your room, for another improvement in bass, they probably wouldn't need much if any EQ either.
 
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