ZMV5 is GO!

[dmalphur]

I just noticed that Zaph's new design is up! I started adding everything to my cart and am really struck by how much crossover component cost has really shot up in the last few years.

Here's a little way to save some costs on the parts.

1. Buy the capacitors from MCM when you buy the woofers. They carry the same Bennics that Madisound does, but have fewer capacitance values to choose from. MCM has the capacitors needed for this project.

2. Use a discount code at MCM for a savings on the capacitors and the woofers. You can use my latest catalog code if you don't have your own: 8HTC15 . This code will make the woofers $14.25 each and the capacitors will be about half what Madisound charges.

The total savings with these tips is about $15. If you get the wire wound resistors at Madisound instead of the metal oxide resistors (the 2 ohm metal oxide is out of stock right now anyways) you can save a couple more bucks.

The total before shipping comes out to $116.24 with these tips.

I'll be winding my own inductors from a 16GA bulk spool I bought a few years ago to save even more cash.

Thanks Zaph for the design. I'll be sure to post pics of my build.

-David

[Rolex]

Thanks for the info. I bought the drivers ahead of time, and now wish that I would have waited so I could combine shipping.. I'm a little nervous of this system to deliver some bottom end, though I'm sure it's a great design since it comes from Zaph. I'm not much for subwoofers, so I don't really want to add one. I was hoping it could replace my 5 1/2" silver flute/Seas H1212 design, but I'm not so sure. These may end up becoming front ported desk speakers for me.

Are you starting the build now?

[HareBrained]

Thanks for the info. I bought the drivers ahead of time, and now wish that I would have waited so I could combine shipping.. I'm a little nervous of this system to deliver some bottom end, though I'm sure it's a great design since it comes from Zaph. I'm not much for subwoofers, so I don't really want to add one. I was hoping it could replace my 5 1/2" silver flute/Seas H1212 design, but I'm not so sure. These may end up becoming front ported desk speakers for me.

Are you starting the build now?

Remodel the enclosure making it deeper. The BSC is dependent on the baffle size but doesn't impact the lower response. The 55-3870 is very scalable regarding cabinet size and you'd be rewarded with a 15L@50Hz or 17.5L@45Hz. FR shape is the about the same but with greater extension: F3(10.6L)=45Hz, F3(15L)=42Hz, F3(17.5L)=38Hz. Play around, look for alignments that will be similar to the original or better. Just an idea.

[dmalphur]

I haven't ordered the tweeters yet (will do today), but I ordered the woofers about a month ago when MCM was offering free shipping. I should have enough crossover parts laying around to piece together the values in the schematic but if MCM does free shipping again soon I'll probably order the capacitors from them with my next order.

I have a design of my own which is very similar to the ZMV5; it uses a 25TAF/DTV tweeter (clearance from Solen) and the shielded version of the 5" MCM woofer. It will be interesting to compare the two when I finish them both.

-David

[Fronn]

Looks like these are a good candidate for replacing my lady's piece of garbage 50 dollar CD changer/tape player/sound system thing. Cheap enough that she'll be okay with it and good enough that I won't want to turn them off (like her current setup - she doesn't like them either).

Looks like a solid design, especially for the price.

[Rolex]

Remodel the enclosure making it deeper. The BSC is dependent on the baffle size but doesn't impact the lower response. The 55-3870 is very scalable regarding cabinet size and you'd be rewarded with a 15L@50Hz or 17.5L@45Hz. FR shape is the about the same but with greater extension: F3(10.6L)=45Hz, F3(15L)=42Hz, F3(17.5L)=38Hz. Play around, look for alignments that will be similar to the original or better. Just an idea.

Thanks for the info. That is definitely something to consider. I like the idea of a 15 liter cabinet.

[Rolex]

On Zaph's site describing this system, he talks about making it a floor standing speaker with a side mounted woofer and an active bottom end. I'm interested in exploring this option, but have not played around with subwoofers before, and don't use an HT receiver. My question is, would I be able to pick up somethink like a BASH plate amp from parts express and use one for each speaker? I'm concerned about how the connection would work. Assuming I didn't have a sub out or pre-out on the receiver or integrated amplifier, I think I would have to use the speaker level inputs on the plate amp and then run the high level output to the ZMV5. Seems a little complicated. Am I missing something? Maybe the solution is to pick up a reciever that has pre outs on it?

Is there a "preferred" plate amp for a system like the one I am describing?

[HareBrained]

Rolex: You could use the 2 plate amps, or one for both sides if you keep the xo low (<~150Hz depending on the slope). I plan on using just one with two TB W6 Neo (one for each side) that PE has on sale this month.

I also modeled the woofer in 8L@60 Hz and it doesn't go as low but does offer more volume with ~2db ripple centered around 125Hz. I'm leaning this direction since my receiver has an 80Hz HP active xover.

[Rolex]

Rolex: You could use the 2 plate amps, or one for both sides if you keep the xo low (<~150Hz depending on the slope). I plan on using just one with two TB W6 Neo (one for each side) that PE has on sale this month.

I like the idea of two plate amps. One for each tower. I'm just wondering though if there is a way I can pull a line level signal from my reciever to run to the plate amps. I would prefer this method over running speaker level cables to the plate amp, then another set of speaker cables from the plate amp to the ZMV5.

Are these the woofers you were talking about:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-832

I'm quite intrigued by these myself.

[fjhuerta]

I love those little Vifas. I bought a pair, dented a dome, and proceeded to buy 3 more

I'm going to build Zaph's Dayton tower, but with the Vifas as tweeters (since that's what I have in hand).

[jkrutke]

2. Use a discount code at MCM for a savings on the capacitors and the woofers. You can use my latest catalog code if you don't have your own: 8HTC15 . This code will make the woofers $14.25 each and the capacitors will be about half what Madisound charges.

Thanks for the money saving tips. Now all we can do is wait to see how long it takes for the woofers to go out of stock. I'm pretty sure Mad has enough of the tweeters.

Madisound emailed me today, after checking my website to see why Vifa tweeters and various components are flying out the door. Apparently the 2 ohm Eagles aren't available anymore. Madisound looked over the various orders and showed that several people got 2.2's, a bunch got 2.0 wirewounds, some got a pair of 4's and some just left it off the order. I have the measured inductance of the wirewound, I'll show that in my blog, along with the 2.2 modeled. Both are acceptable with minor variances.

I'm going to build Zaph's Dayton tower, but with the Vifas as tweeters (since that's what I have in hand).

You might be able to pull out a 2nd order mid-tweeter crossover with that combo.

[fjhuerta]

Thanks Zaph! I was thinking about leaving the crossover frequencies and order as-is, and just modifying a bit the components in the tweeter's circuit in order to reach the same curves as you did with the Dayton tweeter. Do you think a 3.5 KHz x-over frequency with a 2nd order L-R filter would be feasible, then?

[dmalphur]

MCM only has 46 of the woofers available as of end of day today (10/07/08 ). Just in case anyone was wondering; I measured the shielded version of the woofer (55-3855) and the impedance curve is not at all compatible with the ZMV5 crossover, though the parameters do allow a much smaller box. I'll post the impedance graphs tomorrow when I have access to them if anyone is interested.

-David

[Bill Schneider]

I have the measured inductance of the wirewound, I'll show that in my blog, along with the 2.2 modeled. Both are acceptable with minor variances.

John

I measured the inductance of the 2-ohm wirewound resistor which I ordered from Madisound and found it to be very small - smaller than the figure mentioned in your blog. I read .004 mH from which I subtract 0.002 mH for the meter "leads-shorted" reading. That gives 0.002mH for the 2-ohm wirewound resistor. I checked both of the resistors I ordered with similar results both times.



You mentioned that Madisound provided the measurement. Is it possible they measured something other than the 2-ohm resistor to get the 0.017 mH figure? At any rate, with inductance this low, it shouldn't change the filter performance much at all.

[Hdale85]

Did you have it on the 200 ohm setting? Or 2000?

[Bill Schneider]

I was reading inductance (not ohms), and it was set to the lowest range - 0 to 2 mH.

I wish I did have an autoranging inductance meter though.

[Hdale85]

Ohhh hmm. Now I get it. I thought you were saying they weren't the right ohm's or something. My bad....

[Bill Schneider]

Tis' OK, Dougie. Trust me, I know how it happens. :W

The measured resistance was spot on. I measured exactly 2-ohms for both of them.

It's the inductance of these wirewound resistors that is different from what John posted in his blog recently - by a factor of 8-ish. It COULD be a measurement error, but this meter has been fairly good.

Still, I'm at the bottom of the meter's range working with microscopic inductances, so who knows?

[benchtester]

noisy wirewound resistor

I've never trusted the sand cast wirewound resistors since I came across a noisy one.

Not electrical, but acoustic! I was using one for testing an amp, I could hear the song coming out the resistor! :E I am not sure of the mechanism (magneto-restrictive perhaps?) but I doubt it could be ideally resistive.

[tktran]

Could be possible.

I can hear teeny tiny music coming off turntables. Stylus, tonearm?
Who knows.

Hi-fi for sure... :roll:

[dmalphur]

I measured some of the Madisound 2.0 ohm 15W wire-wounds last February and here are the numbers I got. The results are discussed in this thread.

2.0 Ohm Madisound Wire-Wound 15W
0.10 kHz 1.968 Ohm 0.0001 mH
1.00 kHz 1.502 Ohm 0.0004 mH
10.0 kHz 1.503 Ohm 0.33 uH

Something doesn't look right about the resistances at 1.00kHz and 10.0kHz, maybe a typo? I should be getting some more of the 2.0 ohm wire-wounds from Madisound in the mail today. I have access to an impedance analyzer, I will run those sweeps again to see what I get.

-David

[Bill Schneider]

Thanks Dave

I can't change the test frequency with my LCR meter, so your results will be enlightening.

[dmalphur]

There was definitely a mistake in my above measurements. Either I had the analyzer set up incorrectly or I made a typo.

I measured the 2 Ohm 15W resistors I received today from Madisound. Here are the results

R1
0.10 kHz 1.978 Ohm 0.001 mH +/- 0.001
1.00 kHz 1.979 Ohm 0.0013 mH +/- 0.0001
10.0 kHz 1.980 Ohm 0.00119 mH +/- 0.00001

R2
0.10 kHz 1.972 Ohm 0.001 mH +/- 0.001
1.00 kHz 1.973 Ohm 0.0013 mH +/- 0.0001
10.0 kHz 1.974 Ohm 0.00118 mH +/- 0.00001

That clears things up for me, these measurements make a lot more sense. I used a fixture for the measurements this time rather than clip leads. Measurements were made on a HP4192A impedance analyzer with 16047A test fixture.

I'm not worried about this minuscule inductance affecting the performance.

-David

[Bill Schneider]

R2
0.10 kHz 1.972 Ohm 0.001 mH +/- 0.001
1.00 kHz 1.973 Ohm 0.0013 mH +/- 0.0001
10.0 kHz 1.974 Ohm 0.00118 mH +/- 0.00001
...
I'm not worried about this minuscule inductance affecting the performance.

-David

Me either. Thanks for doing this bit of work.

John had mentioned that the (largish) Madisound inductance measurement would still be suitable in his design, but it should be even better than he calculated.