The thought process is surround and height speakers in a small room. Internal volume of 4.5ltr gives me a sealed box size of 174mm x 290mm x 155mm (made from an 18mm MDF baffle and 12mm MDF for the rest of the box). Not planning to modify the baffle whatsoever. Essentially trying to figure out how small I can make surrounds and heights and potentially follow with a normal size LCR down the road if I decide to replace my Adam A7V's (currently have A4V's for surround left and right but as too deep).
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Small 2-way speakers with linear on-axis and power response characteristics (Scan Speak and SB Acoustics drivers). H&V off-axis measurements included
- Thread starter XMechanik
- Start date
Third day of testing, using music, not sine waves from a generator. Without further ado, the verdict is 10/10. The price-to-quality ratio is also 10/10, and the joy of building is 10/10. The kit is incredibly versatile and will work perfectly anywhere from a camper trailer to a 15m² room. A great project, a must-have for beginners.
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Hi Everyone, I am a new member of this forum. Long time lurker. I am in the process of building this speaker set. It's my first DIY speaker project. Done plenty of electronics (EE degree) so crossovers and circuitry in general is not a problem. Wood working on the other end ... Will be fun exercise nevertheless. I have the crossover and drivers ordered. The plywood is also on the way and I am in contact with a local makerspace for help with cutting/routing it. I am considering ordering the PCB's for clean look and am currently ordering some felt for dampening. Still need to get some binding posts and connectors for the wiring.
I will try my best to document and share here, as well as hope to ask many questions and learn from this vibrant community!
I will try my best to document and share here, as well as hope to ask many questions and learn from this vibrant community!
I've moved my mechano23 out of my studio and into the living room. I really wanted to replace the Amiga kit speakers from PE I have had for years and years now.
They certainly sound good out here on their own but need a shelf filter to bring back the lower mids and low end. I'm running stereo out of my UMC1820 and into a Motu M4 (UMC1820 will return to my studio and be replaced by something smaller) with xover filtering handled by EKIO, room correction done with REW filters and EQ APO. Kind of cool that you can run two seperate audio streams that don't really see each other on one OS. So far very stable and sounds amazing.
This does kind of defeat the purpose of my passive radiators, I have some rear panels I made that can screw on in place of the PR's, just have to test them out. I have noticed with PR, the entire cabinet just turns into a speaker and vibrates and I wonder if this has anything to do with the lower mids sound blurry and unfocused, just something I noticed.
Measures good, sounds real good, gets loud, not really much else to ask for. Might adjust the low shelf gain but this response tends to sound pretty neutral to me. Low mids are really important to me, seems to be where all the envelopment is so I tend to elevate that a bit, gives the sound a nice body.
They certainly sound good out here on their own but need a shelf filter to bring back the lower mids and low end. I'm running stereo out of my UMC1820 and into a Motu M4 (UMC1820 will return to my studio and be replaced by something smaller) with xover filtering handled by EKIO, room correction done with REW filters and EQ APO. Kind of cool that you can run two seperate audio streams that don't really see each other on one OS. So far very stable and sounds amazing.
This does kind of defeat the purpose of my passive radiators, I have some rear panels I made that can screw on in place of the PR's, just have to test them out. I have noticed with PR, the entire cabinet just turns into a speaker and vibrates and I wonder if this has anything to do with the lower mids sound blurry and unfocused, just something I noticed.
Measures good, sounds real good, gets loud, not really much else to ask for. Might adjust the low shelf gain but this response tends to sound pretty neutral to me. Low mids are really important to me, seems to be where all the envelopment is so I tend to elevate that a bit, gives the sound a nice body.
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Were you able to locate the DXF files? I am thinking of making some but wanted to see if someone had already done this.
Not as yet. I was going to try doing it through Sketchup but seems a bit longwinded
wineds
Active Member
If you search this thread one member made a 3d printed version which would give you .stl files you could possibly convert to dxf. What are you looking to do? CNC the baffle?
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wineds
Active Member
Low distortion filter upgrade.
After a few days of listening I’m really happy with this upgrade. Any reduction of distortion in the midrange is a must have for me.
I’ve put all the relevant files here in case someone else wants to try it :
github.com
Manufacturing file Low_THD_Filter_Gerbers.rar needs to be uploaded to the PCB vendors site as per the crossover PCB.
The filter needs to be placed in series with the woofer (either positive or negative terminal).
PCB lugs are the same as crossover PCB. There is a minimal BOM low_THD_BOM.xls that provides a number of options for the inductor. The Solen and Jantzen inductors were not ex stock in my region so I bought the 0.13mH Dayton ones and did this ugly hack :
If you use the Dayton 0.13mH inductor remove the cable tie furthest from the termination point and carefully start removing outer windings until only 4 remain. This will result in a 0.11mH inductor. Complete by adding a few new cable ties to aid mechanical stability. I also applied some "liquid nails" to help keep the windings in place. viz:
The 47ohm 5W resistor I used is overkill. A 0.25 or 0.5W metal film resistor can be used instead or omitted if you wish.
After a few days of listening I’m really happy with this upgrade. Any reduction of distortion in the midrange is a must have for me.
I’ve put all the relevant files here in case someone else wants to try it :
Mechano23-xover/Low_THD_Filter at main · wineds/Mechano23-xover
Mechano23 xover. Contribute to wineds/Mechano23-xover development by creating an account on GitHub.
github.com
Manufacturing file Low_THD_Filter_Gerbers.rar needs to be uploaded to the PCB vendors site as per the crossover PCB.
The filter needs to be placed in series with the woofer (either positive or negative terminal).
PCB lugs are the same as crossover PCB. There is a minimal BOM low_THD_BOM.xls that provides a number of options for the inductor. The Solen and Jantzen inductors were not ex stock in my region so I bought the 0.13mH Dayton ones and did this ugly hack :
If you use the Dayton 0.13mH inductor remove the cable tie furthest from the termination point and carefully start removing outer windings until only 4 remain. This will result in a 0.11mH inductor. Complete by adding a few new cable ties to aid mechanical stability. I also applied some "liquid nails" to help keep the windings in place. viz:
The 47ohm 5W resistor I used is overkill. A 0.25 or 0.5W metal film resistor can be used instead or omitted if you wish.
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It was actually purely for aesthetic reasons. I wanted them to look relatively slim in the ceiling. Calculated QTC via Winisd is little under 0.6, which is ok and doesn´t peak. Wharfedales were ok in the midrange (vocals sound good etc.) but there is not nearly enough bass. Cabinet volume is the same as original (2L), so i guess this is the way they are meant to sound.
Hey it's me again with another post for the thread. I just can't stop 
I fashioned some rear panels for my speakers that can take the place of the PR. I figure if I'm going to be running them with "subs" underneath (I cross them at 300hz since the bass woofer is so close to the mechano woofer), why have the PR? I theorized that I was losing some definition in the lower mids due to the rear wall being a membrane. I immediately noticed a difference between the two.
I made sure to do a bunch of repeated measurements to make sure the distortion differences weren't just the room or outside noises. In all of them it looks like the sealed has reduced distortion in the 200-250hz range. The rear panel is quite thin, just 9mm BB which I can and will likely increase it's mass by just gluing some off cuts to it. Subjectively I think the PR sounds better, even hipassed. The closed version sounds choked out if that makes sense.
SPL level not accurate, not sure how loud it was but it was "cover your ears loud". I think I'll be adding that additional distortion notch filter soon.
Passive radiator.
Sealed.
I fashioned some rear panels for my speakers that can take the place of the PR. I figure if I'm going to be running them with "subs" underneath (I cross them at 300hz since the bass woofer is so close to the mechano woofer), why have the PR? I theorized that I was losing some definition in the lower mids due to the rear wall being a membrane. I immediately noticed a difference between the two.
I made sure to do a bunch of repeated measurements to make sure the distortion differences weren't just the room or outside noises. In all of them it looks like the sealed has reduced distortion in the 200-250hz range. The rear panel is quite thin, just 9mm BB which I can and will likely increase it's mass by just gluing some off cuts to it. Subjectively I think the PR sounds better, even hipassed. The closed version sounds choked out if that makes sense.
SPL level not accurate, not sure how loud it was but it was "cover your ears loud". I think I'll be adding that additional distortion notch filter soon.
Passive radiator.
Sealed.
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Yeah, I see a lot of the cutouts here with counter sunk driver holes. Is that necessary? Or do the drivers just sit flush anyways and dont need a recess?
Newman
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- Thread Starter
- #754
Interesting observation. I guess it's the enclosure vibrations that makes the diffrence in the distorsions. According to simulations, the cone excursion in this frequency range is the same for both enclosure types.
Thank you! So 4mm for tweeter and 4.5mm for the midwoofer.
I don't currently have the option of milling the holes and recesses into the front of the chassis.
I was thinking of making the case out of plywood and only 3D printing the front. (18 mm thick - maybe thicker with either 60% infill or 10% + filled with sand)
This way, I can use my printer to design the front in multiple colours (similar to the Sonus Faber speakers). And may try out suggested angled edges..
Would you say that would work without any drawbacks? Which would be better, 60% infill or sand filling?
... Or would one 3D printed part already have all the disadvantages of 3D printing enclosure?
I was thinking of making the case out of plywood and only 3D printing the front. (18 mm thick - maybe thicker with either 60% infill or 10% + filled with sand)
This way, I can use my printer to design the front in multiple colours (similar to the Sonus Faber speakers). And may try out suggested angled edges..
Would you say that would work without any drawbacks? Which would be better, 60% infill or sand filling?
... Or would one 3D printed part already have all the disadvantages of 3D printing enclosure?
- Thread Starter
- #757
Before the audio show, I experimented a bit more with the THD trap. This time I used a 0.1mH inductor and a 5.1uF capacitor, without a resistor. I measured the impedance characteristics of the resonant circuit, disconnected the midwoofer from the crossover, and measured the near-field SPL, where the driver's breakup frequency was clearly visible. I noticed that the two frequencies didn't match very precisely. The impedance peak was at a slightly lower frequency than the breakup (around 7kHz vs. 7.15kHz). I unwinded the coil until the two frequencies matched. Below is a comparison with the measurement of the previous THD trap implementation.
It seems the thd level of the 2.4kHz peak (the breakup frequency is at the third harmonic of this frequency) has been reduced additional few dBs.
It should be noted that this is a comparison with the measurements taken months earlier and I'm not really sure how well the measurement conditions were replicated (background noise, signal levels, driver copies used, etc).
With 96dB level max thd is still around -40dB (i.e.1%), at least not much more.
It seems the thd level of the 2.4kHz peak (the breakup frequency is at the third harmonic of this frequency) has been reduced additional few dBs.
It should be noted that this is a comparison with the measurements taken months earlier and I'm not really sure how well the measurement conditions were replicated (background noise, signal levels, driver copies used, etc).
With 96dB level max thd is still around -40dB (i.e.1%), at least not much more.
See if this series helps. I believe this gentleman is also a member here. Really helpful series of videos on building a 3D printed version.
Watched his videos many many times. They helped me A LOT and were the reason i came up with the 3D printed baffle idea. But i read mixed opinions about 3d printing for speaker housing.
somebodyelse
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Sand on its own, or combined with resin? Plaster of paris mixed with PVA is another fill option I've seen used, as well as some concrete mixes. I haven't seen direct comparison of them all though - just different infill ratios compared, and comparing plaster of paris with and without the PVA. The mineral filled resin and concrete infills come from using 3D printed parts (among others) to make CNC tool frames where vibration resistance is also needed. They found using a sander as a vibration source during filling speeded up flow and reduced voids and settling time. Is the 3D printer you have access to big enough to print the baffle in one piece? Joining parts accurately is one of the disadvantages that may or may not apply.