Another small update, I installed the damping for the subwoofer and got the first testing done. Getting first noise out of a build is always a milestone 🙂
I stiffened the back using Silicium Carbide foam which is very stiff but still very open with 10ppi. I use it also behind the mid drivers to work as a diffractor. It is glued with a flexible polymer glue to the walls to dampen structural resonances.
I first measured with just the driver installed and the whole for the passive radiator plugged to see the behavior as a closed box and check for resonances. There is a small ripple just above 100hz, but it seems pretty well damped. Overall things look good to me.
I then added the passive radiator to see the effect of that. As can be seen tuning comes out at 17,5 Hz which is a bit lower than the 20Hz I was aiming at. I could try to reduce internal volume a bit, but I think I leave it like this as I rather have a bit lower tuning as I still have room later to play with the DSP to compensate.
I also did a nearfield measurement for both configurations where you also can see the tuning. The passive measurement is without the output of the passive radiator itself which should still be summed up.
I also did a nearfield distortion sweep in REW. Result looks pretty good and distortion is overall reasonable low. The third harmonic picks up a little just above a 100Hz which is probably related to the small wiggle in the impedance graph. I might add some polyester foam to dampen this later or just leave it as the level is quite low anyway.
Anything obvious I'm missing? Next up is making the amplifier housing.
I stiffened the back using Silicium Carbide foam which is very stiff but still very open with 10ppi. I use it also behind the mid drivers to work as a diffractor. It is glued with a flexible polymer glue to the walls to dampen structural resonances.
I first measured with just the driver installed and the whole for the passive radiator plugged to see the behavior as a closed box and check for resonances. There is a small ripple just above 100hz, but it seems pretty well damped. Overall things look good to me.
I then added the passive radiator to see the effect of that. As can be seen tuning comes out at 17,5 Hz which is a bit lower than the 20Hz I was aiming at. I could try to reduce internal volume a bit, but I think I leave it like this as I rather have a bit lower tuning as I still have room later to play with the DSP to compensate.
I also did a nearfield measurement for both configurations where you also can see the tuning. The passive measurement is without the output of the passive radiator itself which should still be summed up.
I also did a nearfield distortion sweep in REW. Result looks pretty good and distortion is overall reasonable low. The third harmonic picks up a little just above a 100Hz which is probably related to the small wiggle in the impedance graph. I might add some polyester foam to dampen this later or just leave it as the level is quite low anyway.
Anything obvious I'm missing? Next up is making the amplifier housing.
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I got them on Alibaba. Finding them in Europe for a decent price seemed difficult as you can only buy it in large quantities and if you are a registred company. I payed just below 3 dollars for a 20x20cm piece.
During the Chirstmas holiday I made some progress and this weekend I managed to do the final assembly of all the parts. Overall I'm pleased with how they came out. The 10 off 12mm Nd magnets seem to hold the oak baffle on pretty well. Now unfortunatly I need to wait for a bit better weather to measure outside before I can really dial in the DSP. So measurements to follow.
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Inspiring work...
Using magnets to hold the oak baffle (fascia baffle?) in place is creative. Are you using any damping material between the oak baffle and the sub baffle... to prevent rattles and such?
Using magnets to hold the oak baffle (fascia baffle?) in place is creative. Are you using any damping material between the oak baffle and the sub baffle... to prevent rattles and such?
Nice build and craftsmanship but after all I think the weakest link of the chain is Hypex UcD400OEM. it sounds lifeless and clinical. not real music. I would choice Hypex UcD1800OEM LP (low profile) as it sounds much more musical or the new MP Ncore series. I wouldn't use UcD400OEM for anything above 200-300hz.
Yes between the real mdf baffle where the drivers are mounted and the oak front there is a layer of 3mm sound insultating self adhesive foam. The same foam is between all the double wall panels. It is normally used to decouple drywall studs.
I agree the Ncore series is an improvement over the UCD modules but the cost was not comparable. The UCD series still has a very low distortion level and I can tune with the input buffer and DSP anyway the sound to my taste. I maybe will build a center channel in the same style with a Fusion module. So I can compare whether I can hear any difference.
Still not able to do real measurements as I need a combination of good weather outside and somebody who can come over to help me lift the heavy things on a platform with the current covid restrictions. I was able to do an approximate tuning indoors so I can start listening. Inside I can only manage a 3ms window so I can get good results on the tweeter to mid crossover but am already struggling at the mid to woofer crossover frequency. So, I did a good try with LR4 filters for now and am pretty pleased with the preliminary results. You can hear the bass is still not right, but the mid/high is verry transparent and they have no issue going loud without any sign of stress. Here is the indoor measurement valid above 700hz.
I will follow up with some proper spin measurement. I already constructed a rotating base sturdy enough to turn them. As I own a pair of Proac Response 2.5 speakers as my mains now I put them to the test. These I can lift on my own 🙂 (I also did a pair of clones which I use as rears in my HT setup now). Here are the measurement results measured outside for the original.
I will follow up with some proper spin measurement. I already constructed a rotating base sturdy enough to turn them. As I own a pair of Proac Response 2.5 speakers as my mains now I put them to the test. These I can lift on my own 🙂 (I also did a pair of clones which I use as rears in my HT setup now). Here are the measurement results measured outside for the original.
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In the meantime, I kept myself busy and quickly designed a center speaker to go with my mains. This time a 3-way using the same Scan-Speak tweeter but smaller Wavecor mid WF120CU and assisted by two WF182BD10 woofers. All drivers have their own chambers and baffle dimension is 60 x24cm again angled 7 degrees. Amplification will be kept simpler and done this time with a Hypex Fusion FA123. I played around a bit in Akabak trying to find an elliptical waveguide shape that matches this speaker. Results in attachments.
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I hate to resurrect an old thread and all that, but Jesus, this is beautiful work! You have to update us on how this turned out for you!
I can’t believe more people weren’t following this. I’ve taken a multi year break from building speakers and have recently started getting the itch myself. I was searching around to find info on the mid you used and that’s actually how I found your build thread. Did you get it from a European source? I can’t seem to find it in the US.
I can’t believe more people weren’t following this. I’ve taken a multi year break from building speakers and have recently started getting the itch myself. I was searching around to find info on the mid you used and that’s actually how I found your build thread. Did you get it from a European source? I can’t seem to find it in the US.
Thanks satx,
Very little progress unfortunatly. I got distracted by building a new house and a lot of international travel for work, now that is again possible.
I do enjoy the main speakers a lot. Still plan to do some more measurements one day but I'm happy with the sound as it is. I did build the center speaker although it also took ages to get the Ncore dsp plate amp. I'm not using it at the moment as I had no time yet to set up the filters. Indeed the mid driver is from lautsprechershop in Germany. The phase plug driver is a bespoke model for them I think.