or Connect
AVS › AVS Forum › Audio › DIY Speakers and Subs › SEOS-12 + DNA 360 + Deltalite-II 2512 Build
New Posts  All Forums:Forum Nav:

SEOS-12 + DNA 360 + Deltalite-II 2512 Build - Page 3

post #61 of 143
That orange peel texture will have to be buffed out after each coat. I usually use 320 grit between coats but if that isnt enough to get the texture off, then you with something like 220 or 160
post #62 of 143
Thread Starter 
Well the cabinets have been finished (except for the lining in one), and I started up again working on the crossover. I built up a quick test, and tried it out, and had some interesting issues. The place I'm measuring is far from ideal, since it's indoors and not a very large space, but I've had some trouble that I don't think has to do with the room.



These are two measurements taken of just the woofer in the box (the SEOS was installed with the 360, but not hooked up). The green one was with the crossover network, and the pink one was without the network at a later time. I thought it was weird that the low end would change like that, so I measured the woofer again with the crossover and it still looked like the pink trace. I also changed out the woofer for a different one (also 2512) and got the same result.

Any idea what could be causing this issue?
post #63 of 143
Thread Starter 
Well the bass rolloff turned out to just be a freak incident, and it isn't an issue anymore thankfully.

I'll be posting more about the trials and tribulations of my crossover design process a little later, but in the meantime, here are some pictures of the finished cabinets:


post #64 of 143
Awesome looking.
post #65 of 143
Quote:
Originally Posted by Scott C. View Post

Well the bass rolloff turned out to just be a freak incident, and it isn't an issue anymore thankfully.

I'll be posting more about the trials and tribulations of my crossover design process a little later, but in the meantime, here are some pictures of the finished cabinets:



Scott C.
Your delta-light / 360 build is looking fantastic! I assume this is the Bwaslo design, in the 2 cu' sealed box?
If so; I am building the same ones; from Erich's flat-packs ,and am trailing you by about 1~2 weeks.
Looking forward to your listening impressions!
post #66 of 143
Quote:
Originally Posted by Scott C. View Post
 Since it's kinda cold over here (but not too bad) I'm hoping the extra drying time will help the paint settle out.

Yeah, here in North Dakota I'm really sympathizing! tongue.gif

I've had to hold off on painting until the Spring.

 

I too was wondering about minimizing texture, so I'll reread this later when I get to paint.

 

I'm also interested in how your crossovers went, since I have some concern about if I did everything correctly, and how the room makes me look askance at many of the measurements.

post #67 of 143
Thread Starter 
Quote:
Originally Posted by cuzed2 View Post

Scott C.
Your delta-light / 360 build is looking fantastic! I assume this is the Bwaslo design, in the 2 cu' sealed box?
If so; I am building the same ones; from Erich's flat-packs ,and am trailing you by about 1~2 weeks.
Looking forward to your listening impressions!

Thanks! I'm actually designing my own crossover. It's a first time thing for me, so I built the speaker so I could use Bwaslo's as a comparison (or just build his crossover if I can't get it right, haha)
post #68 of 143
Either way: It's looking great. If I ever get REW setup and behaving (and a quiet house), maybe we can compare FR plots....
post #69 of 143
Thread Starter 
I've got a quick question for everyone. I recently noticed that one of my 2512s is making a slight scuffing sound when I move the diaphragm. It's not noticeable at the frequencies it plays when in the cabinet, but it's got me worried. Tuxedocivic suggested it might be voice coil rub, and that sounds like a likely explanation, but does anyone else have any idea what could be causing this?
Quote:
Originally Posted by cuzed2 View Post

Either way: It's looking great. If I ever get REW setup and behaving (and a quiet house), maybe we can compare FR plots....

Sounds like a plan! I'd be interested to see the differences.
post #70 of 143
Yeah, that would be my guess too based on the description
post #71 of 143
Thread Starter 
Well, I sent in the driver with the voice coil rub, and I should hear back about that sometime next week.

In the meantime, I continued working on the crossover, and I finally think I hit a good stopping point. I'll make up a nice looking digital version of the circuit, and post that, but for now here are the plots for the current crossover.

Horizontal axis


Vertical axis


Compared to PCD design (gray is measurement, unsmoothed gated at 4ms right side)


I probably should have been posting progress as I worked, but it's been a long road with lots of trial and error to get to this. I've got most of it documented on my blog below.
post #72 of 143
Hey Scott. I can't remember if I asked this in our emails...

Is the lack of baffle step compensation a result of the measurement gating, or is it audible or not? Seems to lack output around 200hz. Although the transfer function shows some compensation.

The impedance drop and spike in the transfer function are a sign of probably a 3rd order electrical xo on the woofer? Maybe 4th order? It's not something that needs fixing, but I generally try and avoid this effect. Sometimes a series resistor with the capacitor can help. The big kick at 950hz can sometimes call attention to itself. It's hard to explain and it might even be in my head. It can also make your xo circuit more sensitive to component variation. If it were on the tweeter I'd suggest changing it, but you're probably ok. Just mentioning it to hopefully help.
post #73 of 143
Thread Starter 
Quote:
Originally Posted by tuxedocivic View Post

Hey Scott. I can't remember if I asked this in our emails...

Is the lack of baffle step compensation a result of the measurement gating, or is it audible or not? Seems to lack output around 200hz. Although the transfer function shows some compensation.

The impedance drop and spike in the transfer function are a sign of probably a 3rd order electrical xo on the woofer? Maybe 4th order? It's not something that needs fixing, but I generally try and avoid this effect. Sometimes a series resistor with the capacitor can help. The big kick at 950hz can sometimes call attention to itself. It's hard to explain and it might even be in my head. It can also make your xo circuit more sensitive to component variation. If it were on the tweeter I'd suggest changing it, but you're probably ok. Just mentioning it to hopefully help.

The baffle step is there for sure, but I've been measuring pretty far from walls, so I was hoping it would go away with better placement since I didn't see any baffle step compensation in Bwaslo's design. I'll measure against the wall to see what happens.

Here's what it looks like (smoothed 1/24 octave to make it a little easier to see)
post #74 of 143
Thread Starter 
Ryan, you're right about the 3rd order LP on the woofer. I put a .5ohm resistor in series with the cap, and it definitely helped smooth that bump you mentioned. I also added a bit of an RC contour to help the high frequency extension.



As a side note I've been pretty much ignoring everything below about 600 Hz due to a combination of gating, and some measurement weirdness mentioned earlier in the thread. Basically the low end will randomly appear to roll off way too quickly in the measurements without any actual change to the speaker or measurement setup. (At least while I'm just trying to get things working in the crossover region)

Here's the circuit I'm currently using.

Edited by Scott C. - 3/13/13 at 9:51am
post #75 of 143
in the horizontal axis response in #71, the woofer response seems to shift slightly higher in frequency as the mic is moved off axis. any idea what that is?

and, why does the speaker sitting on the chair in #63 look so darn cool? :-)
post #76 of 143
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

in the horizontal axis response in #71, the woofer response seems to shift slightly higher in frequency as the mic is moved off axis. any idea what that is?

and, why does the speaker sitting on the chair in #63 look so darn cool? :-)

I noticed that as well. I think it's likely due to the small size of the room causing reflections. As I move the microphone off axis, it unavoidably gets closer to the wall. Someone more knowledgeable than me probably has a better answer, though.

And thanks! It's that low camera angle. Makes everything look cooler
post #77 of 143
Thread Starter 
So after messing around some more, and testing outside, I've decided that I don't trust my measurement setup for low frequencies. Whether or not I should trust it up higher is up for debate. In case you're wondering what I'm using, I have a Tascam US-122 mkII USB soundcard/microphone preamp powering a Dayton EMM-6 microphone.

The reason I no longer trust it is first because I don't think the sound of the speaker matches the frequency response I'm getting from the measurements (at least on the low end). It sounds like there's much more bass than the measurements show. Also, despite the fact that I don't have a ton of faith in a Radioshack SPL meter, it showed 80Hz was down 2dB from 1000Hz indoors which is nowhere near the 10dB difference in the REW measurements.

Here's the measurement I took outside (ungated/unsmoothed)



Most recent indoor measurement (gated 4ms)



Does it make sense that the measurement setup might be affecting this? I'm considering getting a different microphone preamp to work with.
post #78 of 143
That does seem odd. Is it ported because the only way I could see this response is with a sealed woofer.
post #79 of 143
Thread Starter 
It's sealed, so I would expect the rolloff to look like that, but not starting at 400-500Hz. Would a leak cause that? I'm using the stock gasket on the woofer because I didn't want to raise it anymore from the baffle, but I can put some more on in case that's the problem.

The box is about 2cuft (maybe slightly more), so this is where I expect it to be:

post #80 of 143
Something seems to be happening in your measurement "system". As you have shown, sometimes you'll have a crazy loss of bass from 800hz and down, and then it'll come back, yet nothing has changed. I don't know what could be the cause, but that seems like a measurement system issue.

Just to give you an idea of how finicky measurements can be. I've had my system calibrated for over a year with both REW and Holm. Taken hundreds of measurements without issue. ECM8000 into a Blue Icicle into USB on computer. Set my AVR to -24.5 and that's 2.83V (or very close) every time. One day, I took a few measurements no problem. Absolutely nothing changed and I took another measurement and got total rubbish. I thought, huh! Checked mic cables, speaker cables. Everything you can imagine. Went into the mic setting on my computer and changed the level by one click out of a 100. No change. Change it 5 clicks and boom. The whole thing works perfect again. Put it back down 6 clicks. Won't work. Ever since I've had to have my mic level changed 6 clicks. Why? Who knows. Oddist thing. And of course my SPL isn't calibrated anymore. mad.gif Even though it ran like a clock for over a year!!!

So, who knows what is up with your system, but something is.
post #81 of 143
Thread Starter 
Yeah, the frustrating part is that I don't really know if any of it is right. If the measurement issues aren't limited to just the low frequencies, then I've been adjusting my XO to account for whatever's going wrong with that.
post #82 of 143
I can overlay my measurement with your measurement of the tweeter.

How do your measurements look compared to manufacturers measurements? Zaph or other measurements?
post #83 of 143
Thread Starter 
Quote:
Originally Posted by tuxedocivic View Post

I can overlay my measurement with your measurement of the tweeter.

How do your measurements look compared to manufacturers measurements? Zaph or other measurements?

That'd be great. Looking at the manufacturer response for the 2512 , it looks reasonably close until about 400-500Hz when it starts dropping more quickly.
post #84 of 143
Thread Starter 
I compared the tweeter to some measurements BWaslo posted (the woofer used was the Delta 12 LFA) and it looked pretty close to me. Here's the overlay:

(link here: http://www.diysoundgroup.com/forum/index.php?topic=9.msg488#msg488)

Purple is my measurement (smoothed to try to match a little better)


Edited by Scott C. - 3/18/13 at 4:10pm
post #85 of 143
Bill has also measured this woofer, maybe he can offer his impulse response measurement and you can compare those as well.
post #86 of 143
Thread Starter 
Just PMed. Hopefully this can shed some light on the problem.
post #87 of 143
Thread Starter 
Well, I'm thoroughly confused now, and no closer to figuring out what's causing the poor bass response with these speakers.

I did manage to find a spot where they looked alright in the bass department. It's a shame that it's on the floor, though.



Here it is in the same room, but off the floor about 2 feet



Finally, I tested a speaker lying around to see if the bass problem was part of the measurement, and this was the result. This is a relatively small ported Infinity bookshelf (maybe 6" woofer)



(above measurements ungated, but smoothed 1/24 octave)

So it looks like the measurements are alright, and it actually is a problem with the speaker. It's got to be something with the box, and not the crossover, since I tested the woofer itself with no crossover, and it gave a similar result. Anyone have some insight into what might be going on?
post #88 of 143
Sent you an email. I think there's two issues. Your measurement gear has played tricks on you in the past, so you doubt some things. And the cross over design leaves out to much upper bass. My email will explain better. I know some designs don't use baffle step compensation. But deciding that is really a judgement call I wouldn't make here based on your initial measurements. Your initial measurements are outdoor and good down to at least 200hz. The woofer obviously has a rising response that needs whipping into shape. Common for a quality low inductance woofer like this. So you need to give it some inductance... smile.gif
post #89 of 143
Is your purple measurement more than 2ft from any boundary (back wall, side wall, ceiling or floor)? It looks like you are experiencing baffle step combined with the drooping response of the 2512. Where will these ultimately be placed?
post #90 of 143
Thread Starter 
Quote:
Originally Posted by coctostan View Post

Is your purple measurement more than 2ft from any boundary (back wall, side wall, ceiling or floor)? It looks like you are experiencing baffle step combined with the drooping response of the 2512. Where will these ultimately be placed?

It's practically on the wall, with maybe 3-4 feet from a wall on the left side (small room, few options for measuring. It won't be placed in this room). They will finally be placed near a wall (1-2 feet away) and probably 4-5 feet from walls on the sides.
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: DIY Speakers and Subs
AVS › AVS Forum › Audio › DIY Speakers and Subs › SEOS-12 + DNA 360 + Deltalite-II 2512 Build