testing wtmw center....crossover help

[spmachina77]

k, guys, this is my first attempt to build a fullrange speaker. As well as build crossovers from scratch.

Anyways, I'm missing a cap for the mid crossover, so could only test out the tweeter and woofers today (without the box).

Tweeter seems to play fine.

The woofers however, are very very quite (I know they will be louder in a box)....but they just seem way to quite. And when I do turn them up I can hear high pitched noises coming from the large iron core inductor (red one in the pic). Is this normal?

can somebody check out my crossover, and see if it looks ok (don't see how I could have messed up with it being so simple.

Is there anything I can test with a multimeter to check?



i'm following dennis crossover, for the seas version of the wmtw

[bmowis]

Hi...

Just finished building my first pair of speakers last month. When I tested out my crossover on the woofers, there was so little output that it had me quite worried. But after I mounted the woofers into the baffle, it sounded 100% better. I wouldn't worry about that part. Just make sure that what you hear out of the woofers is the bottom end and what you hear out of the tweeter is the top end. Your cabinet will take care of the volume.

...as for the noise coming from your xover, try switching out your iron core inductor for an air core. Most of the guys here will tell you that you should not be using iron core, I think.

Brad

[BigJim_inFLA]

It looks as if you have everything wired and labeled correctly, but...the schematic you linked to shows L1031 to be 0.550 mH and the sticker on the inductor in the picture says it's a 1.20 mH. I bet that would make a difference!!

Jim

[spmachina77]

freak....i'm an idiot, you are correct, I swear I check everything 3 times.....but somehow let that slip through. I did all 3 crossovers, and I switched the inductors on 2 of them. Fixing that now

an air core inductor I heard was like over $100 (for that particular inductor), that is why a steel core (was used, seems that what everybody else is using as well for this design).

Anyways, I understand I cant send a full signal to my tweeter, but a full signal (without crossover), shoudl be fine for the woofer right?? Just want to see how the crossover changes the sound (for my learning), cause I still hear some vocals coming through the 8" speakers even with the crossover....I think its right, but not sure how much it supposed to cut out.

[spmachina77]

k, switched the inductors....i'm building the box this weekend, then will just wait till wednesday, cause I missed a cap on my order.

Then I can do some real testing.....

even with the switched inductors thought, the steel core one, still makes...noise , just a little thought, anybody know if this is normal.

My amp shuts off when I turn it up to around 50-60 (out of 77) its an onkyo, i'm assuming this is just cause my amp is only stable to 6ohms, and this is a 4ohm speaker. Its just I have to turn it up that loud to get (the same volume I get at 20 from my regular towers). So i'm just hoping the box will fix that....

[jonathanb3478]

Iron core and steel laminate are not the same thing, I believe. Another term for iron core is ferrite core, I believe. Either way, iron core and ferrite core inductors are classified as "no nos" by many.

A steel laminate for the big woofer inductor is very common, due to the low DC resistance, vs a similar gauge air core.

You must have been looking at a very large gauge foil air core. That would be a bit of overkill. Try this or this, depending on your price sensitivity.

Good luck!

[jonathanb3478]

You do not want to drive a woofer outside an enclosure with high level signals. 50-60 on your receiver may qualify. They are very easy to over drive when they do not have the air in the box pushing back. You would not want to damage it before you get to listen to it properly. Pre boxing it, you just want to check for basic operation (not DOA, in other words). If you see movement/hear anything, stop. You are good to go until you get it in the enclosure. Obviously, as someone pointed out already, you can also make sure that it is not outputting the fr from the tweeter output due to a miss wire, etc.

As a side note, I have an Onkyo SR602 that drives Dynaudio Audience 42 bookshelves across the front three (4ohm) and Monitor Audio BFX surrounds across the back four (6ohm). I have never had an issue with impedance related problems (heat, shutdowns, etc) in the >1 year I have been running this setup. I do not believe that a 4ohm load alone would cause the receiver issue you mention. This is likely another wiring issue with the speakers. I do not know if running the drivers unloaded (not in a box) would reduce their impedance load to the amp, but it is not outside the realm of possibility, either.

[spmachina77]

yeah, sorry it is a steel laminate inductor that i'm using, I just copied a BOM that was listed, and that is what was on it....probably because it was $15 cheaper than the air core one or something....I don't know.

Well....think we just need to put this on hold, i'll post again when I get these put into a box, (maybe on sunday)