barefoot, soffit help

[stone_eufemia]

could you elaborate a little more on the kind of soffit solution you,
wrote up here:

http://www.johnlsayers.com/phpBB2/viewt ... =3342#3342

i'm planning to soffit my alesis monitors (back ported) and your design
sounds like an easy and cheap way to try them.

--how big should the monitor wall be?

--does it have to go all the way from celling to floor?

--how wide?

thanks a lot mate

[barefoot]

s_e,

I don't recommend flush mounting rear ported speakers. This would be a very complicated balance of trying to make the monitor wall large enough to be effective, but not so large such that the path length from the rear to the front adversely affects the low frequency response. I image it's possible, but it would require significant development, probably acoustic simulation software, and good test equipment.

I would suggest trading your monitors in on some front ported types if you really want to flush mount.

Thomas

[John Sayers]

he he - try them soffit mounted first before you swap them :)

just stirring Barefoot

cheers
john

[stone_eufemia]

<I don't recommend flush mounting rear ported speakers. This would be a
<very complicated balance of trying to make the monitor wall large
<enough to be effective, but not so large such that the path length from
<the rear to the front adversely affects the low frequency response. I
<image it's possible, but it would require significant development, probably
<acoustic simulation software, and good test equipment.

i know that, but i tougth it could be a good way to test them and see if
i like what i get.

i think of it as a good DIY project for me 'cause i've never worked with
wood.


<I would suggest trading your monitors in on some front ported types if <you really want to flush mount.

i'll get some other monitors to use as soffited mains and when the time
comes i'll be here asking for advice.

thanks barefoot

i'll try them anyway john, just to hear for myself i may be
surprised with the result

[barefoot]

Well, if you're going to give it a try, then I would build panels about 1.2m wide by 1.5m tall. Put the center tweeter about 3/5 the way from the bottom of the panel and 2/5 from the inner edge (towards the center of the room) of the panel. Mount the panels such that they are angled in 30 degrees and the inside edges are about 15 mm to 30mm from the front wall.

Thomas

[stone_eufemia]

thanks a lot barefoot

i did read in another post about soffit's that the monitor wall should be
3/8" thick plywood, does that still apply to this design?

if not, what thickness shoould i use?

if you look at the plan view below you'll see that's not posible to
space the monitor wall from the front wall by 15mm to 30mm as you
wrote because of the monitor deep, will that make a difference or
should i put another panel spaced from the front wall between the two
angled panels to get it into the 15mm-30mm range?

thanks in advance mate.


*both drawings show the rigth monitor

[barefoot]

Oh, sorry. I meant to write 15 cm to 30 cm (not mm). From your diagram it looks like you should probably lean more towards 15 cm. You want enough space behind the monitors so the panel doesn't act too much like a horn that will load the port - but not too much space so the panel can still act like a continuation of the wall.

I think the panel should be more substantial than a 3/8" sheet of plywood. Thicker, stiffer, denser, and more damped is better. At the very minimum I would use 3/4" plywood backed by a 2"x2" frame.

Thomas

[stone_eufemia]

thank you mate, you've been really helpfull,

i'll have to play a little with the positioning 'cause to close to the side wall
and the sweet spot is outside of the RFZ, which means i'll need to angle the
side walls, i'll try to get a good balance of spread and a big enough RFZ.

i've attached a drawing wich shows speakers placed about 3.5' apart and
still get the sweet spot inside the RFZ.

which should be the minimum distance between speakers to keep a good stereo image?

BTW. have you heard of this? http://www.acousticsciences.com/sil.htm
could it work?, it seems to serve the same prupose as the pannels we've
been discusing here but smaller portable and easier to build.

[barefoot]

Considering your room size this looks like a reasonable design.

I've never heard of those ASC units before, but they definitly don’t look like a good design. They are essentially like adding horns to the front of your monitors. Bad.

Thomas

[knightfly]

Thomas, I just recently discovered that ASC is located only about 50 miles from my house - I've been trying to get caught up enough on other crap to see how friendly they are, and what kind of "tour" I could arrange - if/when that ever happens, I'll be sure to file a sloppy, un-informed (but well-meaning) report ... Steve

[Unfaithful]

Hi guys,

I loved this thread, thank you so much for the designs Thomas!

I was wondering, would this work if I were to flush mount a pair of your Footprint 01s?

Thank you,

Gonçalo

[gullfo]

i doubt you could soffit mount them as they have side mounted bass speakers. which would be even more complex than a simple rear port mounting as Thomas has pointed out (long ago as this thread is many years old) you should invest in front ported speakers for soffit mounting even though rear ported is possible its more complex.

[DanDan]

Which Alesis Monitors? IMO ported designs can benefit from blocking the ports. Either fully with a bung or partially using cotton wool or polyester.