Build studio monitors with Coral Flat10-II's. Help, thoughts and ideas?

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Hi all DIY'ers out there, I'm new to the board and to be fair quite new to speaker design too, so I was hoping this would be the place to get some good advise and help from. Swedish lad, so sorry for the grammar and so... :)

The case is this:
I'm running a small studio that are still in the "build up" phase. (it will always be in that phase, won't it ;) Right now I'm pretty satisfied with my mic collection and console choice so next thing up was finding a monitor setup that I'm happy about. Right now I'm mixing on a set of nearfield Yamaha MSP7 with the additional subwoofer (sounds good and they really do the job actually) and the obligatory Yamaha NS10. But I have long had the feeling of something more, I've never been a huge fan of nearfield monitoring, and have been thinking of something like those big 70's JBL main monitors. A set of accurate speakers to mount way infront of the mixer desk that fill the room with a rich, wide and accurate musical sound... The way you wan't to listen to music.

Ok, sorry, let me get to the point... A few days ago i stumbled across (hang on) 4 x Coral Flat10-II's, all brand new in original never opened boxes. (don't kill me, but to be honest, they where also "almost for free cheap")

I have never really listened to fullrange drivers before, but I mounted them in some old air tight cabs I had, and I know they probably isn't near their full performance, but I was blown away with the sound. Never have i heard so much depths from a set of speakers. I can hear everything that's recorded on the albums, including stuff like someone tapping his foot in the floor, a chair that someone moves on and stuff like that... Downside is that poorly recorded albums sound just that, really poor.. but the good one, Oh my!

Pretty soon I realised that to have a set of these speakers in the studio would really be a good tool for my mixing. You can identify everything, from bad stereo image, rough frequencies and so on... They will probably be a bit hard to listen to for a long period, but since I still have the smooth sounding MSP7's I think they will complete eachother quite well.

Sorry, this will be a (very) long first post, hope someone get's trough it. :)

As I said, I'm a total novice on speaker design. Havn't built anything more than one of those premade kits when I was 15. (15 years ago then...) but U have been reading alot, and I think I got the basics. It's the fine-tuning and a few technical and acustic bits I hope I can find help with from the pro's on this forum.

Now, let's finally get to the plans:
I got these 4 fullrange speakers, and I wan't to get a great set of studio monitors. I've been reading up on the Coral speakers and seen all the different cabinets they have been fitted in. Originals, Coral Beta 5-ports, BLH's and so on.

Since they are going to be in a studio, they are probably going to be hanging from the roof in chains, down to a good hight and maybe tilted a bit down the point at the sweetspot where I sit infront of the mixer table. How is that with horn loaded cabinets? my basic thought was that horn designs might not be the best hanging down? Or am I wrong?

Also, since my lack of skill in designing and woodwork, maybe a basic reflection system is better (easier) to build and could be a good choise.

There is also the fact that I got 4 of those babies. So a big question that I would love to have inputs on: Build four speakers (studio and livingroom at home). Or two MONSTER speakers with double drivers in each. I havn't seen so much fullrange speakers double mounted, is it somehow not a good idea?

The basics I like to get is:

* A good and flat reproduction of the sound.

If i build four speakers I get:

* A extra set of speakers for the livingroom. It's always good to listen alot to the speakers when you not mix on them, to get to know them like your family. And that's a +.

If I build two speakers, I would like them to get:

* A bit better reproduction of the lowest freq's. Two is better than one, isn't it?

* Maybe a bit less "narrow" sweetspot while listening (you are often more then one person at the mixertable) if I mount them vertically.

Also, I was thinking of putting in a extra tweeter to cover the highest part. Tried a pair of cheapo plastic piesos I had in the closed cabs and I liked the results.

In the end, I might also get a proper sub to cover the lowest bits depending on the results I get with this project, but that's a whole different story.

So, anyone willing to point me in some directions here?

Two or four speakers?

Reflex, closed, horn?

Tweeter or not?

Just skip the whole project, buy some old JBL monitors (a totally different thing tough) and live happily ever after?

Best regards! / Anders
Here's what I'd do.

With the cabs you have (assuming they're spare), try stuffing them. Add a port and play with port lengths, find something you like. If you prefer sealed+sub, go with that. I think a sub should be considered necessary anyway, as a dedicated bass driver takes a lot of strain off the FR driver. If you like the sound they make with tweeters, invest a little more (get some reasonable soft domes or something similar), play with the crossover a little. Make it sound as best as you can with these "mess-around" cabinets, then rebuild them, same internal volume, stuffing etc, and add proper bracing etc. This will clear the sound up massively.

I'd make 4 of them, simply because adding another won't help if you have a subwoofer, but you can get problems when they (2 drivers playing the same range in the same cab) interract, cancelling at some frequencies, combining at others. Plus, you get to listen to them more.


PS - I wouldn't recommend connecting them to the TV for general use. I did so with some Fostex drivers, and they rendered most shows unlistenable.
Sounds like a good way to start. I might try to get a better set of "mess-around" cabinet's tough. Something that's a bit more in the right size for the drivers. The one I have right now i just some generic garbage to get a first impression from the drivers. And they are really small. I just might have some old coffee'tables that would do a decent try-out cab. :)

Here's a pic right now, the tweeter in the middle is not connected, just sits there from the old setup. Might be a good start for a reflex port try?

Also, how do i wire the speakers properly if I want to add a tweeter? I would still like the Coral to do full range wouldn't I? And just put a hiqhpass filter on the tweeter? What's the correct setup?


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A larger cabinet would probably help. Still, for now, try the addition of a port in that hole. You might not like it, as the cabinet is likely too small to go ported (they need to be bigger, really...). I'd strongly recommend stuffing, though. It sorts out all sorts of internal reflections (they can come back through the cone), and makes the cabinet seem bigger to the driver, so the bass response will change, too.

Usually just a cap in series will do if it's a super-tweeter. I seem to remember 1uF is a good place to start.

So you'll have the tweeter in series with a capacitor, all in parallel with the Coral. Play around with capacitor values a little to find one you like.
There's a lot of information on the CORAL's.
Pic from here
Singapore NoiSING 2005 DIY Audio Gathering Show Report

You can decide from now, if using it as a mid or not, in your studio. If, in the future you use a woofer or sub you probably can use it in the box you have now, closed enclosure. If building it for under 100Hz, then build one of the new cabinets. Having in mind that the sound will be more detailed if using it above the "moving cone" (LF) frequencies. It seems the PLANAR/RIBBON/AMT is a good choice for tweeter, but as is the soft dome, maybe a pro one because of the 96dB of the driver. Tweeter or not. People say the Beta has a longer extension on the HF, and the Coral Flat-10 not so much. Very nice project ahead...


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