olbonco Posted February 15, 2021 Share Posted February 15, 2021 Does anybody know the DCR or the wire gauge of the forte II, 0.16 Millihenry iron core. I would like to upgrade my crossovers. Quote Link to comment Share on other sites More sharing options...
Alexander Posted February 16, 2021 Share Posted February 16, 2021 Welcome to the board, The .16mH is an air core inductor for the HF and is such a small value (read not a lot of wire) that the DCR would be minimal . The 2.75mH inductor is an iron core and the OEM schematic specifies that the DCR to be less than .4 ohms. Quote Link to comment Share on other sites More sharing options...
Alexander Posted February 16, 2021 Share Posted February 16, 2021 Some typical DCR values would be air core .16 mH 18ga ~.15 ohm 16ga ~.1 ohm iron core 2.75mH 18ga ~.34 ohm 16ga ~.2 Naturally the resistance goes down as the wire size goes up. On my first budget forte II crossovers I used 16ga for both coils and was happy with the results. I went with 14ga on the 2.75mH coil with the next pair built. But unless you push gobs of power through your forte IIs, or you are pk with the extra cost, the 16ga will be fine. Quote Link to comment Share on other sites More sharing options...
olbonco Posted February 16, 2021 Author Share Posted February 16, 2021 Thanks Alexander, Can the 2.75mH be a air core? Does the mH have to be exact? Can it be 2.7 mH or .15 mH. Seems hard to find exact measurements when looking for components. Quote Link to comment Share on other sites More sharing options...
Alexander Posted February 16, 2021 Share Posted February 16, 2021 Sure you could use an air core coil for the 2.75mH. But because it would need so much more wire the max of .4 ohm DCR will force you to go way up in wire size (read more $$). Also, air core coils are a lot more sensitive to proximity of other coils. As for .15 or 2.7mH, I am sure many people have done it that way. In my case I guess I'm just too anal when it comes to spec's. So I would buy the next higher value IE: .18 or 2.8mH - measure them and then unwrap the coil(s) to reach the .16mH or 2.75mH final remeasured value. 1 Quote Link to comment Share on other sites More sharing options...
DavidF Posted February 17, 2021 Share Posted February 17, 2021 9 hours ago, olbonco said: Thanks Alexander, Can the 2.75mH be a air core? Does the mH have to be exact? Can it be 2.7 mH or .15 mH. Seems hard to find exact measurements when looking for components. Personally, I would have no issue deviating from spec as you mention. There is always a a fair amount of variation in component specs. Sometimes they average out if you replace with a lower value, but not always. Capacitance meters are not that expensive if you want to go that route. Remember, you will need to scrape off the wire varnish if you reduce coiled wire in a higher value piece. Quote Link to comment Share on other sites More sharing options...
MechEngVic Posted February 17, 2021 Share Posted February 17, 2021 On 2/15/2021 at 9:58 AM, olbonco said: Does anybody know the DCR or the wire gauge of the forte II, 0.16 Millihenry iron core. I would like to upgrade my crossovers. Truth is, DCR is less important than the impedance of the coil in its position in the crossover. When a crossover is designed, coils are measured in place and the measurement includes any mutual-induction of other coils/components nearby. Variations in DCR or impedance, and even mH and capacitance for that matter, will be impossible to differentiate audibly if values are within about 10% of original. If a coil is close to another coil in the original design, consider that in your 10% range. Crosstalk is the real issue and coils have to practically be on top of one another for it to be an issue. There is an article (the second link I posted) where the guy measures various coil positions, it can give you a fair idea of how coil proximity will raise or lower the overall value. In other words, if you are building a copy of an existing crossover or stuffing new parts on an existing crossover, you'll get real close with just a couple of careful considerations. Here are a couple of links: https://www.youtube.com/watch?v=FrVobPkP6fk http://www.troelsgravesen.dk/coils.htm Quote Link to comment Share on other sites More sharing options...
Deang Posted February 17, 2021 Share Posted February 17, 2021 You should measure a coil while it’s on the board, both inductance and DCR, and match it. 1 Quote Link to comment Share on other sites More sharing options...
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