A little progress on my latest project. The coax sub-enclosure braces the sides pretty well, that and a 'few extra' layers of glue, and corner bracing. I'll be setting up the back to screw in - to adjust /tune the PR (into what sorta looks like a window frame in the one pic).
I've been working on speaker stands for this build.
The speakers are 20h x11w x 13 ¾ (with ¾ grill, which will snug-fit around baffle which protrudes forward ½ in). The stands are ~10in (at the front) and are angled up ~6%, to target listening area.
The boxes are baltic birch, so to try to get a bit more grain in the final finish, round one stained with a dark 'aged barrel', then sanded, and I'll come back with a walnut. Fingers crossed.
A little more progress.
Felted the baffle (still have the fitting of the drivers and trimming) and lined internal walls with self-adhesive ¼ in felt. The stands are designed around the down directed PRs. The plan is to get the drivers all in and start measuring: set the PR tuning, the active Xover set btwn coax and woofer...
Saying good-bye to my open-backs, but hopefully I get some brownie points at home...
I finished the left channel speaker so I could start working on the active dsp Xover between the 8in woofer and the 5in coax, check the PR tuning, and add a little overall EQ (I’m a fan of the BBC dip so took 3.5K with Q2 down 1.5 dB).
Just out of the box I set the HP and LP LR4 @360Hz which seems to work. I set this new speaker up on the left side and my Open Back speaker (two beyma 12s per side) on the right to do a little comparison. IMG 1296 (sorry for the poor quality- I just took a pic of the screen) the bottom line is the OB speaker and the top line is the new speaker. Interestingly while the OB’s roll off under 50 the smaller speaker (with its 10in PR) holds into the mid 30’s.
The attached image: pic.jpg shows the frequency response @18 inches (light green line) with the darker green taken at the passive radiator (downward firing). The PR modeling came out somewhere in between using 0 to 1 plate weights, and I set it up with one. Looks like the PR's max output ~28Hz, the woofer fs is 30Hz. So probably won’t be changing it.
From listening to music I’m thinking about gently rolling off the base as PR’s have a fairly steep roll off, which can tend to accentuate the peak. This speaker has ample low bass output, so I going to try managing in a slightly gentler roll and see if it doesn’t improve the low-end sound quality.
IMGs 1301 and 1300 are with and w/o the grill in place.
I tried the Neutrik speakon for the first time, and used NLR4 4 pole connectors vs two sets of rca's (bi-amp) and actually like this connection (IMG 1304).
Nice, flat response. Looks like these will really dig deep. I like the look of that 90 degree speak-on connector.
If you are using a DSLR, you can eliminate the interference patterns on images such as your IMG 1296-3 photo, by putting your camera on a tripod and then lowering the shutter speed below the screens refresh rate. The image will still be somewhat soft due to the screens low resolution, but you can compensate for this by boosting the contrast and sharpening just a tad.
I went back and tested the PR w/o weight plate (vs 1 in previous test) and the peak moved up to ~33.5Hz. A bit too high, so I decided to trim back a plate (guessing I removed about 20 to 25%, maybe). Trimming the plate moved its peak up a couple of Hzs as vs. the pic.jpg image in my previous post.
Now its time for an adult bev or two, and listen and play around with the positioning (toe in, etc) and some final tweaks to the EQ.
First pic: shows LP woofer crossed (active) with HP coax @ ~20 inches, 360Hz (combined thin purple line). The thicker blue line is net eq'd @ seating position.
Second picture: top thin purple line, as in prev pic, combined @ ~20 inches. Thicker purple/pinkish line (the ugly one) is at seating position with room affects (w/o room eq). While active eq can be over done (as with passive contour networks) there are clear sound advantages. Also, highlights that when we are adjusting our passives by ear we are incorporating the room affects > hence different room somewhat different sound.
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A little progress on my latest project. The coax sub-enclosure braces the sides pretty well, that and a 'few extra' layers of glue, and corner bracing. I'll be setting up the back to screw in - to adjust /tune the PR (into what sorta looks like a window frame in the one pic).
flush routed the top & bottom, with slight trim on edges
routing is best done as an outdoor sport
I've been working on speaker stands for this build.
The speakers are 20h x11w x 13 ¾ (with ¾ grill, which will snug-fit around baffle which protrudes forward ½ in). The stands are ~10in (at the front) and are angled up ~6%, to target listening area.
The boxes are baltic birch, so to try to get a bit more grain in the final finish, round one stained with a dark 'aged barrel', then sanded, and I'll come back with a walnut. Fingers crossed.
I did a similar stain on a BB build a few years ago, and still like that look very much.
A little more progress.
Felted the baffle (still have the fitting of the drivers and trimming) and lined internal walls with self-adhesive ¼ in felt. The stands are designed around the down directed PRs. The plan is to get the drivers all in and start measuring: set the PR tuning, the active Xover set btwn coax and woofer...
Saying good-bye to my open-backs, but hopefully I get some brownie points at home...
I finished the left channel speaker so I could start working on the active dsp Xover between the 8in woofer and the 5in coax, check the PR tuning, and add a little overall EQ (I’m a fan of the BBC dip so took 3.5K with Q2 down 1.5 dB).
Just out of the box I set the HP and LP LR4 @360Hz which seems to work. I set this new speaker up on the left side and my Open Back speaker (two beyma 12s per side) on the right to do a little comparison. IMG 1296 (sorry for the poor quality- I just took a pic of the screen) the bottom line is the OB speaker and the top line is the new speaker. Interestingly while the OB’s roll off under 50 the smaller speaker (with its 10in PR) holds into the mid 30’s.
The attached image: pic.jpg shows the frequency response @18 inches (light green line) with the darker green taken at the passive radiator (downward firing). The PR modeling came out somewhere in between using 0 to 1 plate weights, and I set it up with one. Looks like the PR's max output ~28Hz, the woofer fs is 30Hz. So probably won’t be changing it.
From listening to music I’m thinking about gently rolling off the base as PR’s have a fairly steep roll off, which can tend to accentuate the peak. This speaker has ample low bass output, so I going to try managing in a slightly gentler roll and see if it doesn’t improve the low-end sound quality.
IMGs 1301 and 1300 are with and w/o the grill in place.
I tried the Neutrik speakon for the first time, and used NLR4 4 pole connectors vs two sets of rca's (bi-amp) and actually like this connection (IMG 1304).
Nice, flat response. Looks like these will really dig deep. I like the look of that 90 degree speak-on connector.
If you are using a DSLR, you can eliminate the interference patterns on images such as your IMG 1296-3 photo, by putting your camera on a tripod and then lowering the shutter speed below the screens refresh rate. The image will still be somewhat soft due to the screens low resolution, but you can compensate for this by boosting the contrast and sharpening just a tad.
I went back and tested the PR w/o weight plate (vs 1 in previous test) and the peak moved up to ~33.5Hz. A bit too high, so I decided to trim back a plate (guessing I removed about 20 to 25%, maybe). Trimming the plate moved its peak up a couple of Hzs as vs. the pic.jpg image in my previous post.
Now its time for an adult bev or two, and listen and play around with the positioning (toe in, etc) and some final tweaks to the EQ.
Nice build! I like the vintage feel of the boxes on the tilt back stands. Coax with a woofer/PR is a great design.
+1 for the BBC dip👍🏼
thx guys !
All your time and suggestions, and modeling help > MUCH appreciated
Addressing the room affect with a bit of eq.
First pic: shows LP woofer crossed (active) with HP coax @ ~20 inches, 360Hz (combined thin purple line). The thicker blue line is net eq'd @ seating position.
Second picture: top thin purple line, as in prev pic, combined @ ~20 inches. Thicker purple/pinkish line (the ugly one) is at seating position with room affects (w/o room eq). While active eq can be over done (as with passive contour networks) there are clear sound advantages. Also, highlights that when we are adjusting our passives by ear we are incorporating the room affects > hence different room somewhat different sound.