Make me hurt

[bjackson]

I have posted on this project many times in the past, and probably will some more, however.

In one week my speakers will get back from the painter, and I want you to criticize me to the point of tears (as long as it's constructive so I can fix it! :-).

Here is my exact design.

Fountek JP3 Tweeter with a 4 - 5uF Dayton polypropelene caps on it as protection.

Vifa PL13WG-04 midrange in a 6.68 liter sub enclosure heavily damped.

two Dayton RS270-8 10" woofers which take the most part of the enclosure which is around 210l (Calculated 219 liters minus the internal braces) and ported to 23.5hz with a 4 inch flared port, and the port will be 5.25 inches long, which should give an F3 at 31hz according to Bassbox Pro.

This enclosure is stuffed with 5 lbs of stuffing, and has foam on the bottom.

The system will be actively triamped with a Rane AC23 4th order, with xover points of 4khz, and 500hz.

What can I do to make this better?

[thylantyr]

Add an AGC fuse, fast blow to the tweeter. Try 3/4A - 1A...
better to blow a fuse not the tweeter.

Adjust the crossover while playing music and fine tune it to
your liking, assuming the crossover is able to adjust on the fly
without introducing 'switching glitches' that make your tweeters
make a popping noise. /heh

If you are using low powered amps, upgrade to high power.

That's all for now, looks good.

[BobEllis]

How wide is your cabinet? You might want to set your woof mid XO so that you compensate for the baffle step. Maybe that's why you picked 500 Hz, I don't know. Otherwise, add baffle step compensation.

Does the Rane let you do phase compensation? Consider adding that, if not. See Sigfried Linkwitz's site - you can do it on a small breadboard.

You might want to add a touch of eq to flatten the JP3's rising response.

Geez, now you are getting to making as much circuitry as you ar buying. Unless you already have the Rane, why not consider building a MOXLite - see TIROTH's website, he should have extra boards when the latest group buy comes in.

Bass reflex cabinets don't really want to be stuffed - maybe use batts or foam on the walls to help damp higher frequency reflections, but generally keep them open - especially around the ports.

Measure in cabinet response of your drivers and compensate accordingly.

Hope this helps.

[bjackson]

The Rane (and yes, I already own it), does offer a delay which I am guessing is a sort of phase adjustment, but how in the world do I adjust it, by ear?

I really don't have that much access to my cabinet now. It is limited to what I can get to through the driver holes, but if I removed a lot of the stuffing, what kind of foams are recommended, especially foam that is CHEAP.

As far as adding a touch of EQ, when I am finished I will be listening to music through foobar 2000, so I plan on using digital room correction.

As for measuring the drivers response in cabinet, my plan was to use my laptop to watch an RTA output of pinknoise, and adjust my crossover until it looked good (i.e. the xover points, delay and level).

Anything else that I should be thinking about?

[BobEllis]

Another free measurement option is speaker workshop from www.audua.com that will let you do MLS.

to adjust delay, reverse the connection to your mid, and tweak the mid delay for the biggest dip in response at the XO freq. repeat twweaking the the tweeter delay then restore the mid connection.

If getting your stuffing out is to much of a hassle, don't sweat it much. Just ensure that port and woofers breathe freely (no stuffing blocking the port or back of driver. If you can get a staple gun in through the cutouts, you can tack it up to the walls and top.

www.markertek.com sells acoustic foam about as cheaply as I have seen. It seems to work fine acoustically but it's not fire retardant. Just something to keep in mind if you treat your room.

[soongsc]

Originally posted by bjackson
I have posted on this project many times in the past, and probably will some more, however.

In one week my speakers will get back from the painter, and I want you to criticize me to the point of tears (as long as it's constructive so I can fix it! :-).

Is there a prize for doing that?

[DIY_newbie]

Originally posted by thylantyr
[B]Add an AGC fuse, fast blow to the tweeter. Try 3/4A - 1A...
better to blow a fuse not the tweeter.

Ok sure Thylantyr now you start telling everyone with a ribbon to put fuses on there, about 2 weeks too late for me

j/k


Sounds like a great project so far, I've got the Fountek 2.0 mated to a PR170 and it sounds great.. I'm also using active crossovers with delay compensation and EQ... Luckily the delay compensation was automatic on the behringer DCX2496, just plug in a microphone and let it run for about 2 minutes... Presto, all the numbers are set for you The EQ I will do by ear and using speakerworkshop for my measurements... of course you could always get the DEQ2496 from behringer and it will auto-EQ for room response

Good luck with the project, post some pictures when you get the chance

--Chris
[edit: fixed spelling on thylantyr's name]