• Please note that Audiokarma will be offline briefly for updates early on Monday morning, September 28th.

Minimus 7 Loudspeakers - Measurements

Zonker92, Thanks for the tip. I checked out Mouser and failed to find one. But, I may not be sophisticated enough to search properly.
 
Looks like it's a form of iron core:

http://www.parts-express.com/mfg/jantzen/jantzen.cfm

Jantzen P-Core Series Inductors feature a Permite (ferrous powder) material within the core, which creates significantly lower hysteresis before saturation occurs when compared to ferrite cores. The P-Core Series also features extremely low DCR values and a high power handling capability of 400 watts RMS.
Click to expand...

Here's the same part at PE, except the wire's a heavier gauge:

http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=255-100
 
I just talked to PE, and they recommended that. I wonder if the heavier gauge wire makes a difference.

I was thinking about ordering from Speakerbug, but they are in Australia, and the shihipping was way more than the part.
 
Excellent. My vague impression of inductors in general is that the heavier-gauge wire versions are upgraded, used for higher power handling perhaps, but electrically they should have the same function.
 
Thanks, Michiganpat. Would lower DCR be bad?

The part I have on back order does not have the DCR listed, so hard to compare.
 
The inductor from PE seems to be in stock again. The others will work, as long as the resistance is close to the same and they fit in the cabinet. If read some of Zilch's posts, the inductor was selected mostly for size reasons.:yes:

Post #384
Zilch said:
We selected this one for its compact form factor. You can see how neatly it fits in the cabs.

There's available direct from Erse, as well, but they have a $25 minimum.

I usually just place the PE order, they send what they have, and the B/O'd item(s) come later, as soon as they have them, which is sometimes sooner than stated. Get in the queue.... :yes:
Click to expand...
 
Thanks for that input. I won't worry about matching the DC resistance exactly.

And yes, you are right, PE changed the status of backorder on the inductor today. I should be getting a shipment notification right away. Excellent!
 
:thmbsp:
Amazing how good these little old suckers can sound.

I was looking back at mine and apparently I bought the Erse as specified in the original BOG. What's weird is that the same PE parts number is now a Dayton. I bet it's exactly equivalent, though I could not find the DCR. Conveniently, the Erse had mounting tabs; but that's a minor issue.

Will be watching the builds.:banana:
 
michiganpat said:
will have slightly lower DCR....

how about this?

http://meniscusaudio.com/100mh-sl-p-703.html

Grand Rapids, MI is closer than down under....
Click to expand...

That looks fine, in fact a bit more DCR will not hurt if you can get an even smaller inductor. I do not normally like iron core but the power level is low so it should not be an issue. Laminated cores are usually better as far as distortion is concerned. The inductor DCR is in series with the hook up wire and the driver DCR. Do you use huge heavy gauge hookup wire with these low power speakers? Probably not, so it does not make sense to use a heavy gauge inductor.
 
Problem shoot

This is my first time to try to build a crossover. I get a faint sound ot of the woofer and nothing out of the tweeter. I am sure I made a mistake of some kind. Can anyone look at the photos and tell me what I did wrong?

I was unsure of where to hook up the woofer and tweeter wires after looking at the diagrams from the main page of this thread, so I went with the T+ and T- and W+ and W- in the drawing. The rest of it seemed self explanatory.

Do any of the parts have polarity? That may be something else I did wrong.

Thanks for your input. Here is the drawing and mod summary: http://www.audiokarma.org/forums/showthread.php?p=3671070#post3671070.
 

Attachments

  • crossoverfail1.jpg
    crossoverfail1.jpg
    53.8 KB · Views: 282
  • crossoverfail2.jpg
    crossoverfail2.jpg
    46.5 KB · Views: 244
  • crossoverfail3.jpg
    crossoverfail3.jpg
    50 KB · Views: 250
Double check the wiring of the resistors at the bottom. Also, is the tweeter wire connected to a junction of a resistor lead, and both of the inductors?
 
looks to me as if you have the positive to iron core inductor then on to air core inductor and back to negative, I think that is a short! will check schematic.
 
Looks to me like the woofer and tweeter returns (black wires) are connected to the input red post, not the black post.

Move both of the speaker return wires (black) to the black post.
 
Last edited:
Black wires are indeed on the red post. I will move those and try it. That is pretty elementary. Nobody laugh! It's my first time at this!

68custom, this isn't it. I think I got that part right.

Sirbyrd, I think I am ok on that score as well. I will move the black wires to the other post and give it a try.

I hope I didn't ruin any parts.
 
Moving black wires worked. Time to glue everything down and put it together.

However I discovered that the tweeters don't work. I tested both and then tested one from a working minimus 7 and figured it out. I would appreciate any suggestions about troubleshooting the tweeters to see what is wrong.

Corrected picture of crossover is attached.The next one will be easier, and I know I can make the hardboard a little shorter.
 

Attachments

  • Negative wire correction 001.jpg
    Negative wire correction 001.jpg
    65.7 KB · Views: 197
You must log in or register to reply here.
Back
Top Bottom