Introducing: The Pit Vipers (Ooh Yeah!!!)

[Paul Carmody]

Paul Carmody

I see now that the 5.0mH Iron-Core inductor specified as L4 in the crossover network is back-ordered and delayed through PE until the end of August. 🤬

Is there a suitable substitute for this component without more complex modifications to the crossover ?

Thanks again.
Todd

Honestly, you could get away with any sort of 5.0 mH inductor. Air core, P-Core, Umlaut-core... whatever core. The 5.0 mH value is what counts here. The added series resistance of this vs. that core material is probably gonna be a wash in the final product. The only one I'd avoid is the 20 AWG one, because its Series Resistance is over 2 Ohms! But the ones with ESR of 1 Ohm or less I'd feel comfortable using.

I just don't understand how no one has iron-core inductors right now. I say that because I know some places wind their own inductors in-house. Have they just not been bothering making their own cored inductors, and waiting on the ones to come off the boats? In other words, you may want to call around to the other stores whom I won't name directly here, to see if they'll wind you a pair.

[Serenitynow]

Honestly, you could get away with any sort of 5.0 mH inductor. Air core, P-Core, Umlaut-core... whatever core. The 5.0 mH value is what counts here. The added series resistance of this vs. that core material is probably gonna be a wash in the final product. The only one I'd avoid is the 20 AWG one, because its Series Resistance is over 2 Ohms! But the ones with ESR of 1 Ohm or less I'd feel comfortable using.

I just don't understand how no one has iron-core inductors right now. I say that because I know some places wind their own inductors in-house. Have they just not been bothering making their own cored inductors, and waiting on the ones to come off the boats? In other words, you may want to call around to the other stores whom I won't name directly here, to see if they'll wind you a pair.

Thanks Paul.
Unfortunately , the only 5.0 mH inductors I find have a DCR of 1.3 or above. I don't know what this high resistance compared to your specd inductor will do to the performance of the speaker.
So, I'm hesitant about this decision.

I have everything else ready to order ( except a cap that is also backordered thru PE ) but would like to get everything ready to go.

I've also been working on the enclosure design. I think I need to make it about .75" deeper to account for the bracing I have in mind. This shouldn't be a problem correct ? As long as I keep the internal volume at 2.5 cu ft and the front baffle the same, I should be good.

[djg]

While you wait for one or two items to be restocked, other items may go out of stock. Again, I'd buy what is available now and the rest as it is restocked. Are you going to be done with the cabinets next week? I definitely don't recommend cutting driver holes and rebates without the drivers in hand. There's a whole lotta work that goes into a DIY speaker. Your coils may be available before you have finished cabs to put them in.

[PWR RYD]

You can buy larger wire gauge air core inductors from Madisound or Meniscusaudio. They have lower dcr but unfortunately cost many times more.

[Serenitynow]

You can buy larger wire gauge air core inductors from Madisound or Meniscusaudio. They have lower dcr but unfortunately cost many times more.

I saw them. But, I'm not sure what DCR is safe to go with here.
I'm new to passive crossovers.

PE also has the correct mH Air-Core inductors, but they all have higher DCR.

[Geoff Millar]

Due to the low value of the $A compared to the US, it might (might) be worth looking at ordering from Oz, but if I were you I'd take Paul's advice on what to use.

Geoff

[Wolf]

It is currently hard to get the steel-lam cores for those kinds of coils. This is why they are few and far between.

Wolf

[Serenitynow]

I understand that and thanks for your reply. But, what is the fulcrum regarding DCR in this application? I' ve seen anywhere from .3 to 3.0 DCR in Iron-cores and Air-Cores.
I don't know where the cutoff line vs. performance in this situation falls.

I would think trying to get to the same DCR as suggested in the BOM would be best. But Air-Cores don't seem to go as low as Iron-Cores.

Hence my delima.

[Wolf]

I look at it this way;

14AWG air-core = 18AWG steel laminate; usually these are pretty close. You could likely get by with a 16AWG air on the better side of results. I don't prefer to use smaller than 18AWG SL or 16AWG air on woofers if at all possible to keep the DCR low. Outside of that, Paul's recommendation is sound.

[djg]

It's not like you're going to build a pair with substitute coils and then build another pair with the "correct" coils and do a double blind listening test.

[djg]

Or are you?

[rpb]

This is available.
Jantzen Audio 4.7mH 15 AWG P-Core Inductor Crossover Coil

[djg]

Available. 5.0MH, 14AWG, .59 ohms DCR, $64.

[9sheng]

Serenitynow Are you guys sharing more photos and photos of the crossovers and the originals as you make them? I am also planning to build this great speaker. But I can't start right away, I will have some job changes in the near future, so I will wait 2-3 months before I can start it. So here I am, hoping to see more details on the build process, and learn more.

@Paul Carmody can you share more detailed photos of your crossovers and builds?

[9sheng]

The crossover accessories I used in the last pair of speakers "Classix II", the capacitors used are "BENNIC", I don't know if this brand of capacitors meet the requirements. The PCB circuit board is made by myself (actually I copied someone else's circuit diagram). From this, I learned the PCB design process, and I think I will take another big step forward when I design the PCB next time.

[Paul Carmody]

I'm very brand agnostic. Use whatever brand you can get. What matters most is the value, and that its tolerance is within +- 10% (5% is even better)

Also, that's really cool that you did your own PCB.

[Paul Carmody]

I look at it this way;

14AWG air-core = 18AWG steel laminate; usually these are pretty close. You could likely get by with a 16AWG air on the better side of results. I don't prefer to use smaller than 18AWG SL or 16AWG air on woofers if at all possible to keep the DCR low. Outside of that, Paul's recommendation is sound.

Thanks, Wolf.

After thinking about this, I think the 16 AWG air cores will be fine. Those are available various places. The DCR is slightly above 1 Ohm, but in the grand scheme of things, I think it'll work out just fine. In reality, if these were boutique speakers, they'd probably ship them with 16 AWG air cores and gush about how this offers "superior sound quality over shameful iron-core."

[fpitas]

Everyone knows, iron cores make your music sound ironic.

[9sheng]

I saw the discussion about the L4 coil. I'm still a little confused. I hope to get more answers here. I found 3 options from suppliers and they all have different prices.

​

I know number 3 is definitely ok. But what's the downside of using No. 2? Can No. 2 meet the design requirements? Because I want to achieve the best results while keeping costs in check. As you all see, I still have a lot to buy.
I've also seen iron core inductors like size 1 used on some projects by others, as Paul.C said, you can choose any type of inductor! The question is, is number 1 ok? If it is used, what is the disadvantage compared to the No. 2 hollow coil?
Although the copper wire of No. 1 in the picture is only 1.2mm, I can also find 1.6mm 5mH iron core inductors, and their internal resistance should also be less than 1Ω.

[Paul K.]

FWIW, I wouldn't hesitate to use No. 1. There's nothing wrong IMO with using a steel laminate inductor regarding sound quality, especially in a woofer crossover, and it's sure less expensive. In my Post #101 in this thread, the response for the modeling I did of the Pit Vipers had 0.5 ohms added in series with the woofer to represent the resistance of a series crossover inductor, which is almost identical to the d.c. resistance for your No. 1 inductor candidate. Nevertheless, the Pit Vipers is Paul C's design, not mine.
Paul

[Paul Carmody]

Any one of those 3 is totally fine.

As I said earlier, I'm gonna go ahead and say it's OK to use an air core 5 mH coil, even if its DCR is slightly above 1. It'll work out, and you'll like it :-)