MBOW1 3-Way Repair

[Alex2507]

Maybe that broken resistor lead wasn't the only connection in the XO that broke. Those boards are crowded and if you move one thing, something else down the line might also get nudged.

Send a photo of it to Dennis? He'll know the wiring layout and might see something you don't.

I suck at regular email and pic's but I know how to do it here. Firstly I went through the broke board with pliers and an Ohm meter. It's well put together. There's a little weirdness going on here and there from somebody going in a second time to add the additional binding post cup but I think it's sound as far as continuity is concerned.

Here's the broke one.





I'm going to have to trace that from the schematic but I already noticed some different values on the resistors from what's on the spec's for the revised 3-way. This speaker started as a 2-way and it got modified. That explains the different xo layout. I'm going to swap out the tweeters and give it a test run. It's the only way to know but look at this. This is the other xo.



The layout is completely different. I haven't 'inspected ' it but I know this one works. I've got my soldering stuff out in the truck. I'm glad I brought it home. The last thing to I added to that tool collection was a de-soldering tool. This is the working tweeter.



The broke tweeter doesn't have that resistor right at the tweeter. I'm glad I took that electronics class in HS. Time to put the computer and camera away. I need a work bench. No reason to be on the floor with this. I'm thinking that by now I could have driven it to Dennis, had a coffee while he fixed it and been back home for breakfast.

 

[sawzalot]

I totally agree with the coffee part ! Wheww what cluster fuq of wiring and soldering going on there . I think to get it going again is key here but totally new crossover boards designed by you and fabricated by one of our fabled experts just may be the ultimate answer. I only say this because we have bigger fingers lol.

 

[sawzalot]

Edit ^^ No offense meant either , maybe they are supposed to look like that since its all tucked away out of sight.
Now I want to open up my center and see how that modified crossover looks !

 

[Adam]

Is that second one mounted on cardboard? That's some home cookin' right there - looks like something that I'd rig up with parts around the house. Well, if I had any idea how to do a crossover, that is. As you said, though, they sounded great - and that's what matters.

I forget...did Dennis design/build those? If so, maybe he's got the schematics around for you to use. Well, or as you said, maybe just go visit him and take him out to lunch.

Also - nice pen holder.

 

[Rickster71]

I don't see the lead coming out of the resistor (top left second picture) is that just the way the pic is lit?
Just a note if I may: Lay your inductors flat, with the red cap right next to it. There is a reduction in inductance when a cap is placed directly in the electromagnetic field of the coil. (for example, cap laid on top, not good)

 

[Alex2507]

I don't see the lead coming out of the resistor (top left second picture) is that just the way the pic is lit?
Just a note if I may: Lay your inductors flat, with the red cap right next to it. There is a reduction in inductance when a cap is placed directly in the electromagnetic field of the coil. (for example, cap laid on top, not good)

I think the 1.1 Ohm resistor right at the tweet is to compensate for the effects of the board layout. Just a guess though. I'm almost done testing and then maybe I'll try to pretty up something for the xo fashionistas.

 

[Swerd]

Thanks for the photos. Dennis Murphy's input is what's needed next.

I don't see the lead coming out of the resistor (top left second picture) is that just the way the pic is lit?

I also don't see that lead.

Just a note if I may: Lay your inductors flat, with the red cap right next to it. There is a reduction in inductance when a cap is placed directly in the electromagnetic field of the coil. (for example, cap laid on top, not good)

I'm self-taught in electronics, so I won't argue with your knowledge, but I'm not aware of any DIY crossover building advice about avoiding electromagnetic influences between caps and coils. It might occur, but might be too small to matter with the current levels, capacitance and inductance values involved in audio crossovers. In contrast, there is plenty info about arranging coils to avoid electromagnetic interference with other coils, or speaker magnets.

 

[Alex2507]

I remember that tutorial on coil placement ... well, I remember that there is a tutorial on coil placement. Anyway it's the tweeter. I know it's not firing because I swapped them out from speaker to speaker. Now the test is whether or not it works in the first cabinet I repaired that resistor lead in.


The bad one is on the left.



The bad one.



Dang, $219 for a matched pair?

 

[fuzz092888]

Yea, those Hiq tweeters ain't cheap. Just be glad you're not replacing a RAAL.

 

[TLS Guy]

I suck at regular email and pic's but I know how to do it here. Firstly I went through the broke board with pliers and an Ohm meter. It's well put together. There's a little weirdness going on here and there from somebody going in a second time to add the additional binding post cup but I think it's sound as far as continuity is concerned.

Here's the broke one.





I'm going to have to trace that from the schematic but I already noticed some different values on the resistors from what's on the spec's for the revised 3-way. This speaker started as a 2-way and it got modified. That explains the different xo layout. I'm going to swap out the tweeters and give it a test run. It's the only way to know but look at this. This is the other xo.



The layout is completely different. I haven't 'inspected ' it but I know this one works. I've got my soldering stuff out in the truck. I'm glad I brought it home. The last thing to I added to that tool collection was a de-soldering tool. This is the working tweeter.



The broke tweeter doesn't have that resistor right at the tweeter. I'm glad I took that electronics class in HS. Time to put the computer and camera away. I need a work bench. No reason to be on the floor with this. I'm thinking that by now I could have driven it to Dennis, had a coffee while he fixed it and been back home for breakfast.

Good Heavens!

After a few days away from here being busy with Christmas cooking, those pictures have really ruined my appetite. Who concocted that dogs dinner?

If you string components together like that you will have a lot of trouble and blow gear.

Please just send me the circuit and I will build them properly. That can be your Christmas present for both of us so I can erase that horror show from memory!

 

[Alex2507]

Please just send me the circuit and I will build them properly.

No. ... sorry to have put you through that.

BTW, the 2nd photo shows a broken lead. I managed to drop a blob of solder on the 3mm nib. Then I pushed the resistor up until it hit the blob of solder on the wire above it. I got the whole thing to flow and it passed continuity and tug tests. Now that's the working speaker.

The really ugly resistor right at the tweeter got moved to the circuit board. My connections have orange wire nuts on them for test purposes but they'll get soldered eventually.



The bottom line on the crossovers is that they work. The problem is a blown tweet. That's what I want to fix. I'm hoping a single OW1 shows up somewhere for under $219.

 

[TLS Guy]

No. ... sorry to have put you through that.

BTW, the 2nd photo shows a broken lead. I managed to drop a blob of solder on the 3mm nib. Then I pushed the resistor up until it hit the blob of solder on the wire above it. I got the whole thing to flow and it passed continuity and tug tests. Now that's the working speaker.

The really ugly resistor right at the tweeter got moved to the circuit board. My connections have orange wire nuts on them for test purposes but they'll get soldered eventually.



The bottom line on the crossovers is that they work. The problem is a blown tweet. That's what I want to fix. I'm hoping a single OW1 shows up somewhere for under $219.

No trouble! Just send me the circuit and I will have you a pair of crossovers built, tested and shipped ASAP. Then those can go in the bin. Even the rats will avoid that dinner. I don't want you blowing any more nice drivers!

 

[Alex2507]

No trouble! Just send me the circuit and I will have you a pair of crossovers built, tested and shipped ASAP. Then those can go in the bin. Even the rats will avoid that dinner. I don't want you blowing any more nice drivers!

Dennis might have a schematic for these. I'm not sure if it's the revised version or not. I'm hoping he knows where I can get my hands on a lone driver though.

 

[BoredSysAdmin]

Alex, you should really listen to your wise elders. Tls is speaking the truth. This monstrosity should be painted in blue and thrown into the ocean so no one could ever find it. Starting from scratch or take tls o his offer to rebuild it.

 

[KEW]

I'm still waiting to see how Alex makes this repair into a 3-way!

 

[Alex2507]

Alex, you should really listen to your wise elders. Tls is speaking the truth. This monstrosity should be painted in blue and thrown into the ocean so no one could ever find it. Starting from scratch or take tls o his offer to rebuild it.

I must have something wrong with me. I don't understand the rush to fix the part that ain't broke. It's like being told to fix my hair after I crapped my pants.

I'm still waiting to see how Alex makes this repair into a 3-way!

S'up Kurt! This speaker started life as a 2-way and later got the 3-way revision. There's a 2'^3 bass cabinet with a 10" woofer, a predecessor to the Phils if you will.

Here's the Audiogon link with pic's and the original sale thread as it were.

 

[fuzz092888]

I must have something wrong with me. I don't understand the rush to fix the part that ain't broke. It's like being told to fix my hair after I crapped my pants.

Speaker building OCD OTOH, if a tweeter is shot and you can't use them anyways, why not ship out the crossovers for a free rebuild while you wait for one to surface? If you're going to sit on your thumb and spin for awhile, might as well get something out of it. IMHO, FWIW, YMMV, IDGARAWYD

 

[Rickster71]

....Told to fix my hair.............................I crapped my pants.

Not again?
Maybe you should go talk to someone about it...
Oh... Doug says your hair looks fine

 

[Rickster71]

...I'm self-taught in electronics, so I won't argue with your knowledge, but I'm not aware of any DIY crossover building advice about avoiding electromagnetic influences between caps and coils. It might occur, but might be too small to matter with the current levels, capacitance and inductance values involved in audio crossovers. In contrast, there is plenty info about arranging coils to avoid electromagnetic interference with other coils, or speaker magnets.

I'm going to look through my Favorites. I have a nice link that shows how the value of a coil changes with regards to its orientation (I realize you already know that) and the proximity to other surfaces. (mostly metal)
Since those crossovers were such a mess, I was concerned a cap with a metal package would/could end up on top of a coil. That would have an affect on the coil's value. That's the only orientation/package that would interact.
Now, some of the values changes are subtle. So I don't know at what point it becomes audible. Let me know if you want it in a PM or I'll just post it here when I find it.
For Alex: (The layouts should be/look identical)

 

[Rickster71]

I think the 1.1 Ohm resistor right at the tweet is to compensate for the effects of the board layout. Just a guess though. I'm almost done testing and then maybe I'll try to pretty up something for the xo fashionistas.

The layouts should be/look identical.