got my modula MT's up and running!

[philip_g]

but something is very, very wrong in the mid range, it's VERY attenuated. The vocals sound like they're singing in a bathroom stall, and very muted.


I rechecked the schematic, and off the top of my head everything seems OK, tomorrow I'll pull the XO's and recheck my handiwork. Both speakers sound exactly the same, the XO's were built a little differently and on two different nights so they're not exactly a clone of each other, but I suck at life and could make the same mistake twice.

If you have any specifics to check it'd be greatly appreciated!


And, no pics :P
my craftsmanship on the baffle is too bad to post.

[Dennis H]

Check the polarity of the woofer and tweeter and make sure they're according to the plans.

[Paul H]

After the polarity check suggested by Dennis, maybe you could post pics of the crossover that we would look over.


Paul

[philip_g]

After the polarity check suggested by Dennis, maybe you could post pics of the crossover that we would look over.


Paul

Do I have to?


I'll try to get a pic, but not sure you'll be able to tell much due to the sloppiness of it. I'm not quite able to lay them out as neatly as Jon can, yet.


The polarity is correct, I was very careful about that and just doublechecked. All the wiring is marked on the ends and in the right position on the XO circuit. Maybe I should try to get thomasw's opinion on them, I'm sure his ear is much better than mine.

[ThomasW]

If they don't sound pretty much like live music then something's messed up. Usually it's the XO wiring. It would be rare to have a diffective component in both XO's and equally rare to have a pair of defective drivers.

[philip_g]

What about the acoustic foam in the cabinet? Could that be muddying things up?
All I did was line the bottom and sides of the cab around the woofer, and one piece of foam against the back, behind the woofer (actually on top of the XO) similar to what is seen here

the XO is stuck to the back wall, between the binding posts and the port, in retrospect I don't know why I did that.


after trying out a few different types of music, some are a little better than others, seems like a female voice is high enough that it's clearer. Back to listening!

[ThomasW]

What about the acoustic foam in the cabinet? Could that be muddying things up?

Nope that wouldn't have any effect like what you're describing

[philip_g]

Ok, what about this,
I'll pull both XO's tomorrow and go over them carefully again with the schematic and Dan's photo, if I can't find anything off I'll hand draw the layout and connections clearly, scan, and post. Perhaps a second pair of eyes will pick out what I miss, and I honestly think from a photo there is no chance you'll be able to tell much of anything.

On the bright side the woofers sound like they're breaking in, sounds nice.

[ThomasW]

That's fine.

Also it maybe that Jon has the tweeter padded down more than you're used to....

[philip_g]

That's fine.

Also it maybe that Jon has the tweeter padded down more than you're used to....

Maybe, not sure.

Some songs are Ok, some songs are muddy, it seems like there's a narrow range that is just really muddy, first CD I put in just happened to be in that range, or I'm hearing things :P

thanks for the help. I'll leave it alone until tomorrow.

[GrahamT]

Did you scrape the coating off the inductor ends before you soldered them? (just checking) Also, double check all the solder joints.

I've built two of Jon's designs, and they're effin amazing.

[philip_g]

Did you scrape the coating off the inductor ends before you soldered them? (just checking) Also, double check all the solder joints.

I've built two of Jon's designs, and they're effin amazing.

On the ones that were coated, yep. The rest came tinned, they all flowed great (on the coated ones you can sort of tell)


The joints are mostly great, I'm using heavy wire and had a hard time getting the wire hot enough to flow, even with a 75w gun, but didn't want to overcook the parts so those joints are pretty cold.

Anyway, something is wrong, there's no way it's Jon's design.

[philip_g]

Ok, I went over the XO's again tonight since it was bothering me.

I had the woofer + at R8 and L4 instead of R7 and L4, wrong side.
Now the mid is a little better, but the midbass is worse :rofl:

I triple checked the polarity and the circuit, I found nothing else out of place.

[philip_g]

Ok, here's a pic of my sloppy work.
I'll also attach a drawing of the layout, I'm not sure if it clears anything up or makes it worse, I tried to label the picture but it really wasn't clear. There's a couple places it looks like things cross but don't.

[TacoD]

I have added my interpretation of the schematic. The crossings without a dot in a schematic diagram are no intersections. If I make/ solder a x-over (made douzens of x-overs) I think in means of big building blocks (LCR notch, woofer, zobel, padding resistor) this helps in building a clean x-over.





Please check the whole x-over, I couldn't check your solderwork, because some components are hiding each other.

[philip_g]

Ooooooh, that would be the problem then, I assumed that if the crossing legs aren't marked with a C (I don't know what else to call it) where it intersects, it's a connection.
I'll pull them apart tomorrow and correct them. It's a miracle it worked at all and or I didn't damage something.

[philip_g]

slightly off topic, anyone know who sells new tips for a weller soldering gun? I think mine is going TU and home cheapo doens't carry the tips.

[TacoD]

In europe Weller is almost everywhere available, don't know a U.S. source though. While you're not making shortcircuits in your x-over everything is fine.

[philip_g]

they're big here too, but I can't find just the tip for some reason.
they even give you a spare in the box but I've lost that one I'm afraid

thanks for the help!

[BobEllis]

TacoD - while I generally agree with your interpretation of schematics, in this case it doesn't seem to make sense. My reasoning for assuming that crossings ARE junctions:

1 - none of the other obvious junctions have dots
2 - there is only one net label (those unattached numbers) inthe area - 3
3 - the section by the woofer would be a series string of C-R-C without a junction. Why not use a single C?
4 - over by the tweeter if there is no junction, there is only a high impedance low frequency path around the tweeter. With a junction, it would offer some shelving.

Jon, can you clear up the confusion in your schematic conventions? Thanks

[TacoD]

Hmm you're right Bob, C-R-C make's no sense to me. And a zobel at the WS180 seems a good idea. If I look at the numbering of the componets by lspCAD it looks that C11 is added later. Then I don't understand the sound is so f*cked up.

[philip_g]

hey Bob,

I was thinking along those lines until I really studied the image posted by thomas above, it's hard to see the wire paths, but that XO appears to be wired along the lines of tacod's thoughts.
To be honest, if I did flub it up that badly I'm amazed it sounds as good as it does, all things considered. At least I'm not the only one thrown off, now I don't feel so bad :T

[JonMarsh]

Hello Guys,

Sorry to see Phillip is having problems with the crossover--

I'm at CES and very short on time, but a quick comment- with LSPCAD, there is no junction dot- how you make the crossover drawing is a little tricky compared to other schematic editors I use, but then it has a "drawing mode", and a "simulation mode" (where you can change the component values and where you print from. In the drawing mode, you're dragging the ends of component "wires" with little connector dots, but once connected and you go to simulation mode, the dots dissappear.

~Jon

ANYWHERE you see leads cross or touch, this is an implicit electrical connection! C11 is directly in parallel with L4, for example. The numbers are the electrical node for common electrical connection, which is standard practice in a simulator, which above all else, is what LspCAD is.

[TacoD]

Then I see no errors in the connection diagram of Philip

[philip_g]

OK, so the XO's are at least... somewhat correct then. Crap. I've FUBAR'd something else

thanks for the clarification Jon! Enjoy CES, I owe you a beer if you swing through Denver.

[Paul H]

FWIW I just printed the schematic and compared it to the pic - I couldn't find any errors either, unless there's an extra connection around R8 - it's hard to make out that area in a 2D photo.

Paul

[JonMarsh]

My first guess at what you're describing sonically would be that the tweeter is reverse phased- and you're getting a null (it has a fairly steep one) in the crossover region.

Just to eliminate that as a possibility, TRY reversing the connection from what you have, and give it a listen.

[philip_g]

thanks guys, will do.

R8 runs close to C9, but they don't connect, the lead to R8 is hot glued to C9 to prevent it from shifting, I realize it's sloppy!

I think L3 should look familiar Jon.


The way the terminals are on the dayton tweeter, any chance that pressing the connector against the metal frame could be causing a problem? I can hog out the notches in the baffle and bend the terminals out while I'm there, in case it's putting pressure on the spade.

[ThomasW]

I think L3 should look familiar Jon.

Jon won't remember that years ago he made some inductors that ended up not being used. Those were are what we recycled for your XO

Make sure the tweeter inputs aren't bent inward so they're touching the magnet. Sometimes I put a wrap of electrical tape around the magnet to avoid that problem, particularily of the terminals are real close to it.

[philip_g]

Will do, Danke.

[noah katz]

"it seems like there's a narrow range that is just really muddy,"

Try feeling if there's a cabinet resonance when it's doing this.

[philip_g]

"it seems like there's a narrow range that is just really muddy,"

Try feeling if there's a cabinet resonance when it's doing this.

Nothing unusual, no.

I reinstalled the XOs, quadruple checked the polarity, and insulated the connectors to the tweeter. The midrange is better. Deeper tones are good, something like a kick drum sounds pretty puny. I give up for now :P

mind you they've only got about 10 hours of listening on them at this point. I'm in a cranky mood so I'll toss on some nine inch nails and turn it up.

[ThomasW]

Deeper tones are good, something like a kick drum sounds pretty puny.

Bring them by next week and we can run some tests.

[joecarrow]

Does anybody ever run frequency sweeps to figure out where the problem is?

There are free software tools out there that can output a sine wave at whatever frequency you like (or sweep freely), so if you can connect your PC to your amp you can very easily find out "What does X hz sound like on my system?"

[Jonasz]

Hi Philip,
what's the current situation with your speakers? Would be interesting to know what you think of them with the problem solved.

Jonas

[ThomasW]

He's bringing them to my place later today for testing.

[---k---]

Can I just say I'm jealous! I wish I could bring my subs over to your place.

[philip_g]

sometime after the other 47 errands I have to run today

[ThomasW]

Reversed the phase of the tweeters, all's well with the world...:wink:

[philip_g]

You left out the part where we listened to them for 30 minutes before reversing them

It was subtle, but they're much better now!