[guest60106]

I posted this over on DIY as well.

This not my first loudspeaker build but it is my first OB build. I am ready to set them up and play with them a bit. Unfortunately I have no measurement equipment yet. Maybe for Christmas. I used drivers I had laying around. The Mid/High arrangement is Seas H653 Coax (not the best for OB). I axially mounted the matching tweeter (Seas 25TFFN) to the back of the coax magnet with 4mm allthread and a threaded standoff because the tweeter magnet is pre threaded. Not sure if axially mounting the tweeter makes any difference one way or the other but it seemed as good a place to start as any. I have done quite a bit of reading on OB design. There is so much information and opinion that I felt I would be better off just jumping in and working out the issues myself through testing. The Bass section is 4 Exodus DPL-10s that I bought on sale. I didn’t like the big rubber gaskets they came with so I ditched them (may be a mistake as far as vibration) and cut aluminum rings to flush mount them. The Baffle is 27” wide by 32” tall. My plan at this point is the run them 4 way for the first test. Separate amps/channels for front tweet, rear tweet, midrange, and bass. I have the active crossovers and amps on my current system so it is just a matter of plugging them in. running the tweeters separate will allow me to play with the front and rear phase and gain. I will probably find some major issues with this design but I am up for it and I have to start somewhere. I probably should have built test baffles first, but doing it this way also served to try out a new router I bought and also allowed me to polish my wood finishing techniques a bit. I made the baffles out of ¾” red oak plywood (which upon assembly feels a bit thin). This concerns me but we will see. I may be able to minimize the resonance/buffeting by wiring 2 of the woofers out of phase. I dado cut 2” wide ¾” thick solid red oak for the framing.  The legs and all the hardware I water jet cut out of aluminum. At any rate, take a look at the pics. Let me know what you think. I will keep you posted on the tests.
Matthew

[studiotech]

Looks really nice! God job.

 MiniDSP has a new USB mic that you can use with REW for $75.  I have not tried it to know for sure, but it seems like an excellent value.

http://www.minidsp.com/products/acoustic-measurement/umik-1

Whatever you do, DO NOT wire 2 of the 4 woofers out of phase.  You will get next to no bass at all.  If the baffle vibrates too much, you are going to have to physically reinforce it.

Greg

[guest60106]

Thanks Greg-

I have been considering options to up my game for about the last year. I like the looks of Soundeasy but haven’t committed yet for one reason or another. I like the fact that it has everything in one package but I still have more investigating to do. I am also considering mini DSP’s 2x8 processor as I am using 4 active channels now but with more components and less versatility.

Matthew

[JohnR]

Cool 

The Mid/High arrangement is Seas H653 Coax (not the best for OB). I axially mounted the matching tweeter (Seas 25TFFN) to the back of the coax magnet with 4mm allthread and a threaded standoff because the tweeter magnet is pre threaded.

Interesting idea. Why do you say the H653 is not the best for OB?

There is so much information and opinion that I felt I would be better off just jumping in and working out the issues myself through testing.

 

[jtwrace]

I like the use of DR-25.  You must be involved in aerospace or motorsports.  Yes?

Oh yeah, nice build too.   

[guest60106]

Hi John,
I don’t think it will be too bad but only testing will tell. I am skeptical of using it for a few reasons. For one it is a 6 ½” driver and most designers lean towards larger drivers for the mid in OB applications. It has a lower Qt (.31) and less x-max than what I would consider ideal. It does however have a fairly high BL of 7.4 so it should tolerate a bit of power as a mid-driver without over extending. Again, this is my first swing at OB and I felt more comfortable starting with parts I have on hand and going from there. I have been building speakers for a long time and there is always plenty of time to spend more money. Just ask my wife.
Matthew

[guest60106]

I like the use of DR-25.  You must be involved in aerospace or motorsports.  Yes?

Yep. Mechanical engineer for a NASCAR Cup team. Good Guess.

[jtwrace]

Yep. Mechanical engineer for a NASCAR Cup team. Good Guess.

We have something in common...

[MJK]

Very nice, I like the driver layout and look of the finished speakers.

[2wo]

I have some serious garage envy going here...John 

[guest60106]

First impression,
I removed my existing mains, connected the OBs and did a sound check to make sure all the drivers were working correctly. I set the bass/mid crossover point @ 250 and the mid/high @2500. I set the gains equal on all channels and popped in some mild vocals (America) at low volume. The after walking back and forth and doing a second sound check by ear all was well. I hit pause and backed up the CD to the start, added some volume and sat down in the listening chair and hit play. Good but thin. I hit pause again, added about 6 db of gain to the bass drivers. Hit play again. Nice. Full and robust….certainly no lack of bass here. A bit too much into the midrange so I turned the crossover point down to 200hrz. That helped. The vocals are clear and well placed in the staging. The imaging is wider and deeper than my existing mains and the highs are not as harsh. This is interesting because I am using the same midrange and tweeter drivers in the OBs that I used for my exiting mains. I popped in Steely Dan Aja and pulled out the stops on the volume. WOW! Great stage and depth. These OBs do not sound thin at all, which was my main fear when I decided to build them. It may be the fairly small room but there is no need for a sub what so ever. They are a bit fatiguing at very high volume levels but I have no way to measure them yet. I will do this sometime in the next few months when I decide on a software package for measurement and design.

I am sure I have enough in the design at this point to work with once I can get a measurement curve. I am actually very surprised that the OBs are as plug and play as they are. They need work but at this point there is nothing overly objectionable. With my existing mains I had to spend weeks working on the sound and re-adjusting to get it right. It only took me about 45 minutes to get the OBs to sound better than them. I walked into the kitchen and the sound is much more balanced from the other room than it was before. I don’t know why. With my existing mains I have a much greater loss of bass when listening in another part of the house. With the OBs the sound is much more balanced when going from one room to another. Also, my next step is to build traps for my listening room. My suspicions for a long time have been that the room is too live which is why loudspeakers tend to be fatiguing at high volume. I could very well be wrong about that but taking measurements will tell the truth.


Until the next update.

Mathew.

[matevana]

Hey Matthew,

Nice build!  Since you have quad amp capabilities and a miniDSP you may want to try something to address the fatigue you are experiencing at higher SPL's.  By looking at your design and seeing your x/o points,  I would bet you are lacking in the lower mid register. This can cause fatigue due to an imbalance.   

Try splitting the 4 Exodus drivers as follows: Lower pair 100 Hz down. Upper Pair 100 Hz to 500Hz. Coax driver 500 Hz to 4k. Tweets 4k and up.  Now spend some time getting the levels just right. This can be a bit tricky but one good way is to play pink noise from a test CD and take dB readings for each of the 4 ranges with a simple radio shack SPL meter. Ideally they should match when the levels are right.

I have also found that in set-ups similar to yours, the highpass on the bass drivers can be most critical. Pay particular attention to things like the lower registers on the piano. They should not only sound realistic but convey the proper weight of the keys in the lowest 3 octaves. You may also have some luck by inverting the polarity on the coaxial driver.

If you should try this, it would be great to know your listening impressions.

[guest60106]

Hey Matthew,

Nice build!  Since you have quad amp capabilities and a miniDSP you may want to try something to address the fatigue you are experiencing at higher SPL's.  By looking at your design and seeing your x/o points,  I would bet you are lacking in the lower mid register. This can cause fatigue due to an imbalance.   

Try splitting the 4 Exodus drivers as follows: Lower pair 100 Hz down. Upper Pair 100 Hz to 500Hz. Coax driver 500 Hz to 4k. Tweets 4k and up.  Now spend some time getting the levels just right. This can be a bit tricky but one good way is to play pink noise from a test CD and take dB readings for each of the 4 ranges with a simple radio shack SPL meter. Ideally they should match when the levels are right.

I have also found that in set-ups similar to yours, the highpass on the bass drivers can be most critical. Pay particular attention to things like the lower registers on the piano. They should not only sound realistic but convey the proper weight of the keys in the lowest 3 octaves. You may also have some luck by inverting the polarity on the coaxial driver.

If you should try this, it would be great to know your listening impressions.

matevana,

All good input that I have not thought of. Thank you.

I am not running a Mini DSP although I am running 4 active analog channels so I do have the capability to try the things you suggest this weekend. I also have a bunch of OC 703 that I am going to stack around the room in different places to see if deadening the room helps.

Once again thank you for your insights.
Matthew

[studiotech]

Well, without some basic measurements this is all a big guessing game, BUT if you want to try something like mentioned above, run all 4 woofers all the way down, cross the lower pair somewhere btw 100-150hz and let the uppers run all the way up to the mid xover point.  This way you maximize your low end surface area.

Greg

[guest60106]

I added some bass traps and played with speaker positioning. The traps allowed me to raise the bass crossover point up to about 300 Hz and bring the bass level up about 3db. This resulted in much tighter and defined bass, much more mid bass punch and greatly reduced the fatigue at higher volume levels.

After quite a few listening tests moving the speakers around, I settled for a position further out from the wall (total about 3 feet) and less toe-in(almost parallel to the wall) than they were originally set. This resulted in a much wider and deeper sound stage.

Next I will be adding traps to the ceiling and the back wall (opposite the speaker wall) and playing with the laid back angle of the speakers.

Matthew

[matevana]

I added some bass traps and played with speaker positioning. The traps allowed me to raise the bass crossover point up to about 300 Hz and bring the bass level up about 3db. This resulted in much tighter and defined bass, much more mid bass punch and greatly reduced the fatigue at higher volume levels.

After quite a few listening tests moving the speakers around, I settled for a position further out from the wall (total about 3 feet) and less toe-in(almost parallel to the wall) than they were originally set. This resulted in a much wider and deeper sound stage.

Next I will be adding traps to the ceiling and the back wall (opposite the speaker wall) and playing with the laid back angle of the speakers.

Matthew

Matthew,

You mentioned that things improved when the speakers were placed parallel (less toe-in).  I'm wondering if your tweeter levels are set too high? Not the crossover point but the amplitude. Since you prefer the off-axis sound this could be the case. Try lowering them by 3-6dB. At first it may sound lacking, but keep listening. When you come back to it, the sound may be more proportional. 

[guest60106]

Nice!

Wife gave me Soundeasy V18 for Christmas. As soon as I can I will get the hardware I need and learn to take some measurements.

[matevana]

Nice!

Wife gave me Soundeasy V18 for Christmas. As soon as I can I will get the hardware I need and learn to take some measurements.

Damn. I got ties.