TD12M, DE250, SEOS 12...Active Design

Bill might be able to provide the SEOS-12/DE250 On axis measurement for you. FR/Phase should be a great start and since its active there is no real concern about impedance and maybe impedance data isnt needed.

here is the TD12M FR data I used to build my active XOs.

http://www.penngray.com/htroom/measu.../TD12M_FRD.txt

If we can get the SEOS/DE250 on axis FR data, we can start some XO design. We will have to figure out the real dB difference between the two to better match the plots up together.

Im confused, wouldnt the best way be to just take FR response measurements at listening position then match up the levels that way?

You will want to import them into a simulation program, or take a close look and make some guesses. Then you program the mini to apply the required slopes, eq, shelving, offset, delay, etc.

PCD has an active section. It's free. But kind of limited. I don't have much active experience, so others may have better suggestions for a program.

I really think it would be awesome to use PCD. We have so few XO design threads on this forum, it would be nice to see how the PCD works.

I would use speaker workshop myself. I found it far easier to build something over PCD (Im not a fan of spread sheet software packages either).

Normally, yes someone would measure both drivers and find the relative differences but the SEOS-12/DE250 + TD12M isnt in anyone's hands so we have to start somewhere.

Its not going to make a difference if the measurements (that exist) can be matched up with a very small difference.

Plus its a great to get a jump and have some fun learning to build an XO!! Practice is important.

Of course If someone wants to send me the SEOS-12/DE250 I will do the measurements. I have a box that should fit the SEOS-12 well enough and it has the TD12M already.

If you can get the measurements rallied up I could get you going on PCD.

Without measuring both drivers from the same design axis how do you guys plan to solve any time alignment differences?

With that said, I'm all for some crossover design threads once people can take actual measurements from a single design axis. PCD seems kludgy at first, but once you get used to it, it is extremely easy. I've never done any active designs using it though so I don't know how well that part works.

You can get that later if you use minimum phase, no?

I've only done it with PCD for fun. Never applied the results. It seems fine, but limited.

Have the SEOS-12/DE250 measurement done an inch or two below the horn which is probably close enough to the center of any speaker box build for this combo.

Other then that time alignment can be calculated/estimated well enough and with active we can simply change values to get it more accurate AFTER the speaker is built.

This is not the first or last time measurements have been used without a box to mock up an XO...lets not let fussiness get in the way of experimentation.

Again, If one of the designers has the TD12M then maybe they can post measurements. If not then Bill/EricH can ship me the SEOS-12/DE250 and I will measure the box and post the measurements.

I do want to try PCD and I want to see a full build done on here. Its could be a cool open project.

I guess it matters less with an active setup where you can use delay. For a passive setup, I would prefer having the design axis measurements.

Here's the SEOS/DE250 file, measured at 1m. Sorry, but I didn't recored the test level, so sensitivity will have to be determined from driver specs.

DE250+SEOS15FR.frd

Edit: Oops, this is for the SEOS15. I don't think I've ever touched a SEOS12. Did a SEOS10 a while back, no SEOS12.
(I'd use a SEOS15, myself, anyway, but that's just me....)

Of course you and 99.9% of all other designers would

When that does happen I hope the design is posted. It would be interesting to see what is truely different wrt end results.

Either will work for your design. This is assuming you purchased the TD12Ms correct?


or a bunch of hacks getting it all wrong ......Im one of those HUGE R&D type guys that will tell his employees get their hands dirty screw it up, learn from the mistakes and create a solution. I tend to not hire the ones that fear failure.


I think this is fun though, I wanted to play with PCD more then what I tried originally.

The SEOS-15 is the choice I would have too but its up to Smokarz, will the SEOS-15 look too big over the TD12M? The QSC was 14" over top of the TD12M and it looked okay this is even bigger though.

TD12M is 94.1dB
DE250 is 108.5dB

The SEOS-15 might not look bigger than the QSC due to its larger roundover. We haven't seen it mounted in a speaker.

I definitely agree to using the SEOS-15 over the SEOS-12 if you can afford the extra width. It allows for a wider range of crossover options to try and it is generally preferred to control directivity as far below the crossover as you can get away with.


The M gives up some extension but aside from that, IMO it is a superior option for your purposes. I ordered a pair for an office system. It will be used with a TPL-150H, but I plan to mount them to a baffle with a SEOS-15/DE250 for modeling purposes.

I plan to design crossovers for the SEOS-15/DE250 and 2226J/TD12M/TD15M. I might work with the SEOS-12 too and I'd be open to trying other woofers if people want to send them. I'll probably buy some 4550's too.

visually too big??

Give some more details like room dims and setup. Maybe we can make something work. I highly recommend using a toe-in where the axes cross in front of the primary listeners. This can be made to less box width at the expense of more depth.

smokarz,

I'm working on a basic .csp file for you to get started in PCD, along with some screen shots and a bit of a guide. I doubt many people use PCD for active work, so I'm hoping it'll be useful for lots of people.

The frds links in this thread use spaces rather than tabs so they don't wanna run through response modeller to get minimum phase. Any chance, to those that posted the measurements, they can post the HolmImpulse file and I can extract it, or post the text like that before but with tabs? Otherwise I'll try and do it in excel or something. Not sure how though.

In the meantime though, download Jeff Bagby's PCD and fire it up. It'll probably look like garbely gook, but hopefully my screen shots will make sense of it for you.

penn,

where did you place the mic for your measurement of the td12m?

is your enclosure sealed or ported? the rolloff seems kind of abrupt (-8db at 100hz).

Probably his start frequency and gating. My measurements typically look like that too.

Smokarz, I'll get those screen shots posted tonight.

re tabs vs double spaces

you can open a .frd in ms word and then use replace ALL to replace all the double spaces with tabs....
works for me when importing into xls when overlaying comparing multiple response files

Oh, that is good to know. Thanks!