Inductor DCR Insanity For SDA's

machone

I measured 106.7 ma output on my "low resistance measurement circuit".

I measured the inductors in my 1A's and used ohms law to calculate the following:

Tweeter = 0.68 ohms
SDA Tweeter = N/A (Removed)
Stereo Mid = 3.31 ohms
SDA Mid = 3.31 ohms
Stock Bass Woofer = 1.45 ohms

Replacement Solen for Bass circuit = 0.91 ohms (rated by Solen @ 0.91 ohms)

I have already replaced the bass inductors with the Solens with great results.
I deliberately revoiced the woofer circuit for more deep bass. I tried three different inductors to get it right.

I looked at Solen and Jantzen and cannot find inductors that match the tweeter and mid circuits and I don't want to mess with the voicing.

Experts: Any suggestions?

gimpod

Comcast dumped all personal web pages for some reason. Here's the chart again





COULD THE POWERS THAT BE PLEASE MOVE THIS IMAGE LINK TO THE FIRST POST IN THIS THREAD REPLACING THE ORIGINAL LINK "http://home.comcast.net/~gimpod/Polk/Inductor-DCR.jpg" WITH THIS ONE. also it might be a good idea to make this a sticky. Just a thought.

westmassguy

Agreed

[Deleted User]

I'm not sure what you're asking for.

txcoastal1

KennethSwauger wrote: »

I'm not sure what you're asking for.

In the opening of the thread, there was an inductor jpg link that is no longer working.

I think Tony would like the image in his last post moved to the opening post of this thread....I think this is what he wants?????

Nightfall

He wants the stock inductor value chart edited into the original post of this thread.

gimpod

KennethSwauger wrote: »

I'm not sure what you're asking for.

Ken about 5 paragraphs into the first post in this thread there is a line that says "Inductor-DCR.jpg" that use to be a link to the chart above "http://home.comcast.net/~gimpod/Polk/Inductor-DCR.jpg" this link is dead now that comcast has dumped all the private web pages. So I need some one to change the old link "http://home.comcast.net/~gimpod/Polk/Inductor-DCR.jpg" to http://www.gimpod.com/Polk/Inductor-DCR.jpg

Thanks.

[Deleted User]

Is that the way you want it?

gimpod

No, It was an inline image above the paragraph you have the link in now.

Nightfall

Just put the [IM G] [/IM G] tags around the link in the first post, without the spaces between the M's and G's.

[Deleted User]

How's that?

gimpod

Yo da MAN! Ken Perfect.

You want fix / rebuild my Teac X-10R? ($$$$$ ouch )

Thank You.

[Deleted User]

No problem...

Schurkey

I've been researching inductors for my SDA SRS 2 pin/blade speakers. Took me a long time to find the inductor chart above. It's not linked-to on Gimpod's circuit-board site (that I can find.) I'd seen it years ago, so I knew that it existed.

I have questions about inductor DC resistance: All the Jantzen inductors that I'd need for my speakers are lower in resistance than the Polk inductors listed in the chart. All "my" inductors seem to be 22 gauge except the monster SDA inductors, and I already have iron-core ERSE inductors for that.

Jantzen P/N 000-0973 = 0.130mH +/-3% 0.31Ω wire 0.63mm=22AWG OD-25 / 8mm
Not a perfect match for the OEM Polk due to slightly less DC resistance. (0.31 ohms vs. 0.37 ohms. Is 0.06 ohms critical?)

You list the (000-)1489 Jantzen as a replacement for the 0.40mH Polk inductor, but the Jantzen is similarly lower in DC resistance: 0.640 ohms vs. 0.687, or 0.047 ohms less.

Jantzen P/N 000-0974 = 1.25mH +/-3% 1,21Ω wire 0,63mm=22AWG OD-32 / 15mm
Continuing the trend of the Jantzen being slightly less DC resistance than the OEM Polk, 1.210ohm vs. 1.329 = 0.119 ohms less.

Jantzen P/N 000-1119 = 2.5mH +/-3% 1,840Ω wire 0,63mm=22AWG OD-38 / 15mm
As expected, lower DC resistance 1.840 ohms vs. 1.953 = 0.113 ohms less.

1. Can I expect that the Jantzen inductors achieve lower DCR for the same wire gauge based on less wire used (and more-precise winding)? Are they using finer-grade wire?

2. Can I expect that the Jantzen inductors' lower DCR is not a problem? The slight difference from OEM won't affect speaker voicing, or cause other concern? I'm thinking that the resistance of the drivers will so completely overwhelm the ~0.1 ohm resistance of the inductors that the inductor difference is immaterial--but I've been wrong before. My drivers have more difference in resistance among them than a tenth of an ohm--some driver sets are more like 1-ohm from highest to lowest.

westmassguy

@Schurkey , + or - 5% is fine for the inductors. When I replace inductors, I try to keep the Inductance value < 1%, and DCR < 5%. When moving existing Inductors from the old boards to Tony's boards, I measure them, and also adjust them to be <1% between the left and right channels. I've seen some pretty wide variances from what the schematic says is supposed to be there, and what is actually there. Some Inductors exceed 10% tolerance.

machone

Not good to hear about the unbalance

Schurkey

westmassguy wrote: »

+ or - 5% is fine for the inductors. When I replace inductors, I try to keep the Inductance value < 1%, and DCR < 5%.

All four of the Jantzens I listed are more than 5% lower DCR than the OEM inductors, comparing the specs in Jantzen's .pdf catalog, and the DC resistance chart provided in this thread and on Gimpod's site.

I have an LCR meter, but I'm guessing it's not sensitive enough to truly match the inductors with. I'll give it a shot and see what happens, though.

I am going to order the Jantzens anyway, unless I hear (fairly soon) that this is an outright mistake. I'm in no mood to transfer inductors from the old boards to the new Gimpod boards. If I knew of a better match...I'd consider it.

wwwparts-express.com e-mail:


Thank you for contacting Parts Express. We notified the manufacturer of your specific needs and received the following information from them. We can special order the items you requested. The cost would be as noted below, plus shipping and handling based on the weight of the item. There is a $25.00 minimum order requirement for special orders. It would take 7-9 weeks to receive. When submitting a special order to the manufacturer, the order would be non-cancelable/non-refundable. In the event you would like for us to order for you, please notify me and I will submit an order for you. If I can be of further service please let me know. All of these with the quantities you requested would meet the minimum.

Jantzen Audio model number 000-0973 0.13mH, 22 gauge $2.73 each
Jantzen Audio model number 000-0974 1.25mH, 22 gauge $4.52 each
Jantzen Audio model number 000-1119 2.50mH, 22 gauge $5.75 each
Jantzen Audio model number 000-1489 0.40mH, 22 gauge $3.30 each
Mills resistors in the 2.7-ohm value, 12 watts, cannot special order as they have a 100 piece minimum


I anticipate placing the order in a couple of days...unless someone talks me out of it.

westmassguy

Schurkey, I wouldn't obsess on it too much. All the old Inductors were hand wound. Inductance and resistance varied widely. Some were wound very uniformly, while others looked like a three year old did them. Did Polk buy oxygen free copper back thn? Was the coating the same? Did they buy from the same vendor or manufacturer for all their coils? Who knows. All that information is long gone. If it were me, I'd place the order, measure them when you get them, try and get the inductance within 1% between the left and right crossovers, and be done with it.

Just for shites and giggles, measure the old inductors once the new crossovers are finished. I think you'll be amused by what you find.