Measuring Leroy R's Minions III

[patrickm]

[1 reserved for final version]

[patrickm]

Re: Measuring Leroy R's Minions III

[2 reserved for final version]

[patrickm]

Re: Measuring Leroy R's Minions III

I started replying with this info in Leroy's Minions II and III thread, and then realized it was in the gallery and this was better suited here.

There are now some preliminary measurements available, and more to follow. due to constraints on time and volume levels, these measurements still leave something to be desired. only the FR on-axis and distortion were taken at 90db levels, much was done around 70db, and some 80ish db in between. i also need to better characterize the room before i call anything final. all of the ones shown in this post are done with omnimic's blended method. i'm interested to try jeff's method, but excel doesn't live on this PC, so that's going to take some more time.

all testing was done with the minions III (w3-1053sc) in a 4.5" external cube made of 1/4" baltic birch, with a 1/4" roundover on the baffle and heavily stuffed (4" internal cube). for this first round, the only BSC filter tested was one i ballparked prior to building them, L=0.5 R=4ohm. the sub mentioned in some of them is this one under development for this project.


comparison of the raw minions with the BSC & sub. yes, this is an unfair comparison, but i wrote over the image with BSC and no sub and realized it later. (this will get re-done). but ignoring what's below 200hz, i think it shows the BSC circuit is an overall improvement, although without more testing, i don't know if it's the best BSC filter. i'm assuming at this point the dips around 100 and 200 are artifacts of the sub's phase and/or the room.


distortion measurements at 90db and 80db, with and without sub. notice that as you get louder, the distortion peaks become more significant, especially around 550hz and below 200hz. at 90db, some of these are around 3%. at 80, they're closer to 1.5%. as expected from a small full-range without any high-pass applied, there's a good bit of distortion under 100hz.

[patrickm]

Re: Measuring Leroy R's Minions III

and since i was limited to 5 images per post, here are the two sets of 70db off axis-measurements together.

off-axis of original, w/sub, no BSC, ~70db. brightest line is on-axis, darkest is furthest off. ignore the blue.


off-axis of original, w/sub, with BSC, ~70db. brightest line is on-axis, darkest is furthest off. ignore the blue.

[donradick]

Re: Measuring Leroy R's Minions III

Thanks - I've been thinking about these.

[fixthedoor]

Re: Measuring Leroy R's Minions III

Another thanks. I just started eyeballing the TB for use in a computer system, along with the Voxel.

[Navy Guy]

Re: Measuring Leroy R's Minions III

Interesting info. Based on the graphs, it actually looks the flattest with no BSC and listening 15 degrees off axis. So basically no toe-in sitting next to your computer monitor should be good. When you guys did your comparison, did you toe them in or point them straight forward?

[fwiler]

Re: Measuring Leroy R's Minions III

Thanks for the info.

I built these out of 1/2" maple. They aren't bad if you can place them close to solid wall.
At work they sounded horrible because we have those noise cancelling partitions. So reflections off the back by the computer screens get absorbed.

I'd be curious how a couple of these in the same box sound together. I think most amps could handle the load.

[Leroy R]

Re: Measuring Leroy R's Minions III

When we were listening at my house, we just had them pointing straight forward with no toe in.

[patrickm]

Re: Measuring Leroy R's Minions III

Interesting info. Based on the graphs, it actually looks the flattest with no BSC and listening 15 degrees off axis. So basically no toe-in sitting next to your computer monitor should be good.

well, yes and no. skipping the BSC and being a few degrees off-axis should sound good, especially keeping the 9khz peak in check. but given that your ear is much more sensitive to level variations in the midrange, the one with BSC keeps this critical part of the FR more stable for small movements off-axis, or so it seems. it also does extend the perceived bass level.

[ejh2854]

Re: Measuring Leroy R's Minions III

Patrick,

I'm putting a couple of sets of IIIs together now, and was curious to try your addition... looking through PE's crossover parts listing, I see this 0.5mH inductor:

http://www.parts-express.com/jantzen...uctor--255-036

...and something akin to this resistor:

http://www.parts-express.com/dayton-...esistor--004-4

...for the 4 Ohm value you called out... correct choices? At least one pair will be doing surround duty, flown in room/ceiling corners.

If you had to do it again- would you use the same values? Thanks for any suggestions!

Ed

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[patrickm]

Re: Measuring Leroy R's Minions III

ed - those should work fine. the coil is probably the same one i had on, and you could even use the cheaper 016-4 resistor instead.

i lost my OS hard drive that had all my measurements on it to a mechanical failure so i need to recreate it, but i did find the 5" external dimension cabinet offered no real advantage over the 4.5". i was still going port that one, though, and see how much difference it makes.

for a corner/ceiling duty, i think the 0.5mh/4ohm should be more than enough BSC, it's possible you might want less. you might want to even add the 2.2ohm or 2.7ohm resistor to the cart. if it sounds like too much, use one of the lower resistors and unwind the coil to taste, probably in the 0.3-0.4mh range.

[ejh2854]

Re: Measuring Leroy R's Minions III

Thank you! I'm knocking out a pair of five-inchers to start, although using 1/2" for the baffle and rear panel instead of 1/4" stock everywhere... have two pair of the W3-1053SC, and since you can build a bushel of 'em from $6 worth of MDF I figured a few variations would be fun to play around with.

.

[Leroy R]

Re: Measuring Leroy R's Minions III

I didn't have a .5mH coil, but did have a .6mH and tried that with a 4 Ohm resistor and didn't like the result so I'm guessing that was too much BSC. Waiting to see what Patrick settles on so I can see if I have those components in my inventory. I don't want to unwind the .6s because I think I actually bought those for another project that isn't finished yet.

[ejh2854]

Re: Measuring Leroy R's Minions III

A pretty good-sized bag o' crossover parts is only a few bucks, so I figured I'd grab a few of this-and-that in the range you guys have discussed... figures I've already got a box headed this way from PE, which I could have pushed over the free-shipping threshold with a little more scrounging.

.