DIY 2225J, 2445J, 2405 Build Help

[Lee in Montreal]

If your DSP has a time align function (using a microphone), that will make a lot of difference too. And quicker than doing it by ear... ;-)

[danvprod]

Here are some measurements (8 IR average around the listening position 1/6 octave smoothing) of just the HF, LF and combined response.

Currently using a 80 Hz 6 dB/octave for the LP, and 800 24 dB/octave for HP. The CD is about -12 dB trimmed from the woofer now.

Certainly needs more tweaking.

I do have the option to time-align my individual outs on the MiniDSP. I can put in up to 7.4 ms of delay on each channel. It is not automatic, though. What's the best way to do this?

[danvprod]

2226:
100Hz 6 dB/oct LP
40Hz 12 dB/octave HP
0.3ms delay on woofer (matched IR peaks 1m from center of woofer/CD).

Woofer peak was 3.58 ms, tweeter 3.808 ms, delay set 0.3 on woofer to align. This is with the x-overs engaged when measuring.

2445:
650Hz 24 dB/oct HP

EQ:
2226:
60 Hz +4 dB Q2 Peak
160 Hz -6 dB Q1 Peak

2445:
6000 Hz +8 dB High-Shelf.

In-room response from 8 position measurement per trace around listening position.

[danvprod]

Some progress:


Following the guidance of a great thread on DIYAudio, I began experimenting with "Quasi-Optimal" crossovers, to better time-align the drivers given their physical offset.


Currently trying a La Cleach arrangement, which is:


3rd order Butterworth Low Pass, -3dB @ Fx*0.87 (+)
3rd order Butterworth High Pass, -3dB @ Fx*1.15 (-)
Offset = 0.22*c/Fx


I did end up having to add an additional 0.2ms delay to the woofer to get them into alignment, but as the measurements show, I am measuring good combination of the drivers in the crossover region:


Yesterday, I put together a simple bracket system to elevate the 2405 above the horns, and also to better align the voice coils of the CDs and the supertweeters, since they are being crossed over passively. I also flipped the polarity on the 2405 because of the 12 dB/octave phase shift. I'll have to confirm this with measurement.


I don't love the bracket, but it should work for now until I build something nicer.


My 300b amps are currently in for service, so I am running the CDs and STs with a ClassD amp, so I can't give an accurate impression of the improvements that the crossover and super tweeter bracket have brought to the final system, but I should have my amps back this week, so I will be able to judge then.


Open to ideas about improving the bracket.

[Champster]

I just joined the forum and am thrilled to become a part of this great community of Lansing Fans!

I am building a system very similar to yours with the same challenge you ask about crossover frequency between, in my case, the 2235 and 2446 so I added a 2206 and plan to cross the 2235/2206 at ~100. 5cf vented for the 2235 and 1cf sealed for the 2206. That allows me to raise the xover to the 2" substantially. I'm hoping to around 1k. I will be using the miniDSP 4x10hd so the final points are still to be locked down. I was thinking of having the 2446/2405 xover between 8-10k.

I am still assembling parts and yet to build cabinets and would love feedback.

Thanks,
Paul

[danvprod]

Cool, Paul!

Sounds like you have the components to make a great system. For me the cabinet was designed around the parts that I had on-hand. Namely, the big horns for the 2446 dictated a lot about the design (15" sub cabinet with the midrange horn on top). I am pretty happy with my cabinets, but if I had to do it again I'd:

1) Make the full 5 cu ft cabs, not the ~ 4 cu ft that mine came out as.
2) Make the cabs out of plywood and not MDF.
3) Think about a better way to mount the horns.

I still do want to either upgrade my MiniDSP to an 4x10 HD, or perhaps an analog crossover. For the time being, I've not really felt the need to tweak anything because I've just been enjoying the music. This spring, I am going to finish the cabinets with dura-tex. I still need to sand and finish up the backs of the cabs, and I have been contemplating adding handles to make them a bit easier to move around (they live on the third floor of my house, which makes moving them up and down a challenge).

I do still need to make a better horn mount. I am waiting for a chance to pick up the JBL 2509A adjustable driver mounting bracket to mount the 2446 on. Then I would be able to bolt that into the cabinet and have a bit more permanent solution than what I am using now. These are details at this point. I've not had any issues with crossing over my 2446s at 400 Hz. I don't play them anywhere near their max SPL, and am only driving them with a 7 watt 300b amp.

I'm interested in where you will take your build!
-Dan

[danvprod]

Finally getting back to these after a few months. I sanded the bass cabs down, routed the edges, filled gaps with vinyl spackle and coated with duratex. The duratex is awesome. Goes on easily, creates a nice finish and no priming required. Very highly recommended.

[danvprod]

Here is how they look back up in my listening room. I still need to build a better mount for the 2" CDs and super tweeter. I want the midrange horn to be 10" or so higher and have the super tweeter mounted between the woofer and midrange. Next project...

Any ideas?