Notch filter for Tangband W3-871

[cj.9]

I'm going to be building John's TangBands. http://home.new.rr.com/zaph/audio/audio-speaker11.html
I would like to order the notch filter parts from Part's Express along with some other items.

Will the parts listed below be close enough?

Part's Express
.70mH 18 GA PERFECT LAYER INDUCTOR (dcr=.39ohms)
Part Number 266-820

DAYTON 6.5 OHM 10W NON-INDUCTIVE RESISTOR
Part Number 004-6.5

DAYTON 8.2uF-250V POLYPROPYLENE CAPACITOR
Part Number 027-426



Thanks

 

[cj.9]

Would this inductor be ok? it's about half the price as the first one i listed.

JANTZEN .70mH 20 GA AIR CORE INDUCTOR
DC Resistance: .57 Ω
Part Number 255-042

TIA

 

[Timn8ter]

The resistor and cap should be fine. The issue when subbing inductors is the DCR value. It's best to stay as close as possible to the designers values. Unless there is a particular reason you want to purchase from Parts Express you could get the exact parts John used from Madisound.

 

[cj.9]

Thanks, I intended to order from Madisound but I have an order ready at PE. I was hoping that I could avoid another set of shipping charges. We get hit pretty hard in Alaska.

I'll take your advice and go with Madisound.

 

[Timn8ter]

Don't get me wrong. That's exactly what I was wondering. It's hard to justify another set of shipping charges for a couple of $3 inductors. John's inductor was .41 DCR and the first one you listed is .39 DCR. That should work fine.

 

[Zaph]

Don't get me wrong. That's exactly what I was wondering. It's hard to justify another set of shipping charges for a couple of $3 inductors. John's inductor was .41 DCR and the first one you listed is .39 DCR. That should work fine.

Right, that's so close that it doesn't even matter. Should be fine. Crossover components aren't nearly as critical as some people think.

About the only time time it's critical is when building a filter for a high Q breakup, when the notch has to be a precision strike on a sharp peak. In those cases, the L and C are much more important than the R. The TB 871 in-box response peak in the midrange is a very low Q peak.

The other time it's mildly important is on the low pass section of a woofer crossover. For example, in a crossover designed to use a heavy gage steel laminate, going to a cheap air core will probably suck some efficiency out of the system and change the crossover rolloff a bit.

 

[cj.9]

Thanks guys.
Also I would like to thank you both for the websites and designs.
I'm planning to build 4 of John's sealed, .129cu.ft. boxes and Tim's center (w/3 of the W3-871's}.
I'm considering the TUBA 18 for the sub.

Any thoughts on the TUBA?

 

[Timn8ter]

Any thoughts on the TUBA?

I've not built it but it's very popular and highly regarded. Based on Bill's recent article in AudioXpress I'd say it's easily worth the money (very affordable) and effort to build. The only problem now is MCM is backordered on the driver (Bill may have had something to do with that).

 

[cj.9]

MCM is backordered on the driver

I know, I may have to go with the TB W8-740 that's listed as the substitute.

 

[cj.9]

I completed the Tuba18.
I posted some photos at Photobucket

Questions and comments can be found at:
http://audioroundtable.com/BillFitzmaurice/ar200502060400.html
About halfway down, Tuba 18 progress.

http://img.photobucket.com/albums/v284/tuba18/Picture019.jpg