ZD3C Crossover oops

[jheizer]

I am working on a ZD3C and made a tiny opps when buying the crossover parts.



I accidentally bought a 20 gauge 1.5mH inductor vs a 15 gauge as called for. Got caught up in the hurrying to make the order while the RS180s were on sale and messed up.

So as a crossover noob. This is a 2 part question.

1. Am I screwed and should I make an order for the 15 gauge or you think I will be fine? I hate paying shipping for one tiny thing.

2. Since I am trying to understand as much as possible along the way here is what I think would happen. The inductor is part of a 2nd order low pass and the resistance is not changing that crossover point. The added resistance from the low gauge wire will slightly reduce the output of the woofers but not very much. The PE page says the 20 gauge inductor is ok with 200 watts RMS and I am powering this from a mid level Denon with 110 watts so I won't be getting close that that number.

Am I close? What do the pros think?

[HareBrained]

Your analysis is correct. The DCR is 1ohm vs. 0R38. That will only impact the midwoofer SPL but it depends on your listening environment. Personally, I prefer to have a solid midbass and would exchange them. PE has a liberal return policy.

You could try them but then you'll be out both shipping and the cost of the 15ga. inductors (unless PE is still willing to take them back, which they might.)

[lhwidget]

Actually, there will be one other subtle change. The added resistance will affect the overall Q of the system, raising it slightly. The bass response will increase slightly in the F3 reigon (less electrical damping).

I'd try it both ways just to see if I could tell the difference, it's part of the fun!

[jheizer]

Thanks for the feedback. Good to know I was almost there. I was building the crossovers last night and realized I ordered a 7ohm resistor vs 6 ohm for the notch for the mid so going to be making an order. Was most likely going to get the correct inductor anyway but now will for sure I guess. At least I got the rest all together with out any more wrong parts. What you get for rushing a cart together.

Great the mid has been out of stock and expected to come in today. Now says out of stock till 12/15. Ugh!

[peepaj]

I had the same thing from PE, although their site says 12/15 there's a good chance yours is on the way. I was told that they only got enough to fill back orders. I hope that is the case for you.

[jheizer]

What I was hoping happened but I didn't want to ask and find out otherwise. haha Waiting 2 months would suck.

[fbov]

... You could try them but then you'll be out both shipping and the cost of the 15ga. inductors (unless PE is still willing to take them back, which they might.)

... I'd try it both ways just to see if I could tell the difference, it's part of the fun!

Get the feeling we like to see how things sound?

One more way to have fun with this would be to model it. Zaph has FRD (frequency response data) and ZMA (impendence) files for all his drivers, and you have the XO schematic. All you need are the crossover simulation tools...

http://audio.claub.net/software/jbabgy/jbagby.html

and/or

http://www.pvconsultants.com/audio/frdgroup.htm

My guess is that the predicted difference will lead you to stick with the 20 gauge... and that's exactly the right time to listen to both to hear how big a perceptual difference the prediction yields.

HAve fun,
Frank

[jheizer]

Thanks. I think I will model it up tonight. I had played with modelling stuff before when I was trying to adapter 2 other center channels to possibly fit in the spot that this one is now going. I found myself clicking and guessing too much so have been trying to take a step back and be able to look at the circuit first and have an idea what it is doing without aid. Figured before when I posted this if I saw a change I wanted to make sure I knew why. Thanks for the help everyone.

[Ray_D]

Here's a plot



I built the ZD3C and I measured the drivers and modeled them in SoundEasy. I have attached a plot to show the effect. As you can see it is a couple dB on the low end. Whether you could tell that with real program material is questionable; but I would recommend you get the lower resistance part. John designed it with less than full BSC assuming it would be fairly integrated in a HT; so there is no real right answer depending on you setup. This is a terrific center channel.

Regards

Ray

[jheizer]

Thanks for the comparison graph. It didn't have as much of an effect as I expected. Going to order the correct one though. As much as everyone seems to love this center I am damn excited to get it built.

[jheizer]

I must have been on their shit list. My mid just finally shipped today. Already got the other crossover parts last week and have them finished. Looks like I am building another box this weekend. Spent Saturday building some cheapo RS100s-8 into full range speakers to replace my desktop satellites. 6L tuned to 60hz with the logitech 10" ported sub. Actually a decent "sub" for computer use. Not bad for a $45 build using the cheap vinyl veneer.

Edit: Might as well throw up a few pics of the minis. Not the greatest full range speakers but the computer EQ helps smooth them out. Used the Cherry Vinyl Laminate as I didn't feel like finishing them nice just to sit on my desk.