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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

Finished my build a while back. I opted for the PR option. If I could do it all again I would probably go for a port to reduce cost and make the build easier.
Made the cabinet from scrap pieces outdoor grade ply wood I used for my outdoor kitchen. I didn't have much experience in woodworking and used the old tools in my dads barn. God that stuff was inaccurate. Really hard to get true corners and straight edges. I'm a bit of a perfectionist my self so re-did the whole cabinet and bought some tools for it.
Later decided to add bracing, round-over the front edges, mount the crossover to the top, and added some padding on all walls. Also added the recommended amount of polyfill (no pictures).
All in all a really fun experience and definetly learned alot! Here are some pictures I took during the process.

Terrific build well done!
 
Initially I didn't compare them and tought they sounded really 'muddy'. When I visited my parent I tried the speakers there and still had the same impression. Did an unscientific test comparing it to their speakers (cheap 2-way sony 4-5 inch bookshelf) and that sounded better in the mid/high frequencies but didnt have the extension or body the mechano23's have. I suspected some resonance so I set them up next to the salon and crossed them over at 50hz to a sub using a minidsp SHD. Did some in room MMM measurement and indeed found a strong peak around 300hz. I want to find out if that is a room mode or a cabinet resonance of some sort since it's also in amirs THD measurement. But I've not had the time to check

View attachment 406420

I then knocked the highest peaks down using some EQ (in the graph below also the top end of the mechano23 is eq'ed to tilt a little less downward to try to match the 'openness' of the salon, unfortunatly I don't have a measurement saved with only the peaks knocked down) resulting in the following:
View attachment 406421
The sound of the mechano23 was MUCH cleaner now! Sound was really well balanced tonality wise. Yet the salon2 sounded way more open/detailed. I then tried to tilt the high frequency a bit up on the Mechano23 to try if I could match that open/detailed character of the salon. It semi worked. There was more detail now but ofcourse the tonal balance was now completly off and it didnt sound natural anymore. So my initial conclusion is that when the peak/resonance is taken care of the sound is good and balanced. yet it lacks open/detailed sound compared to the salon2. I'm not sure if this is due to the wider dispersion of the salon. I noticed that a lot of highly regarded speakers have an estimated in room response that gradially declines to about 2kh and then turns to flat. I added some examples below:

F226BE:
View attachment 406429

Salon2:
View attachment 406430

Blade2 meta:
View attachment 406431
This looks really great, hard to believe the enclosure is made of scrapped outdoor facilities.
Those high frequency roll-offs seem a bit suspicious to me, but maybe I'm just not very familiar with MMM measurements. Have you measured both units? Are the results identical? Are you able to do a simple impedance measurements and a gated SPL on axis measurements?
 
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This looks really great, hard to believe the enclosure is made of scrapped outdoor facilities.
Those high frequency roll-offs seem a bit suspicious to me, but maybe I'm just not very familiar with MMM measurements. Have you measured both units? Are the results identical? Are you able to do a simple impedance measurements and a gated SPL on axis measurements?
I would like to dig a little deeper. Next week I have some time. I've measured the individual drivers with the crossover installed when I didn't have the back on the speakers yet and those results looked pretty good. I'll post them tomorrow.
How do I make an impedance measurement with a sealed (PR) enclosure (I do have a Dayton DATS)?
I think gated is gonna be hard since I only have a umik1 USB mic at the moment?
Regarding the moving mic method: it's just an in room far field measurement where you move the mic with a constant noise sound playing and the results are averaged. My room is quite reflective.
 
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I would like to dig a little deeper. Next week I have some time. I've measured the individual drivers with the crossover installed when I didn't have the back on the speakers yet and those results looked pretty good. I'll post them tomorrow.
How do I make an impedance measurement with a sealed (PR) enclosure (I do have a Dayton DATS)?
I think gated is gonna be hard since I only have a umik1 USB mic at the moment?
Regarding the moving mic method: it's just an in room far field measurement where you move the mic with a constant noise sound playing and the results are averaged. My room is quite reflective.
Let us know! One question - what does PR enclosure mean? Does it mean that it doesnt have the port on the back?
 
Also, I'm making my pair out of MDF - do y'all think the bracing is needed (connecting the side cabinet walls)? Could it affect the sound in any way?
 
do y'all think the bracing is needed (connecting the side cabinet walls)

I would opt that this type of enclosure reinforcement does not have a big effect. I had this resonance present in the prototype pair in which this enclosure bracing was installed and the problem looks similar in my second pair with no bracing. But the topic of whether some other (and what) reinforcement should be installed remains open. I perceived the resonance in listening as sometimes noticeable but not very problematic. In measurements it comes out clearly on the impedance characteristic. On the spl (gated) characteristic it is practically invisible. I expected it to appear on the Klippel spl measurement from the review by @amirm, but even there you can't see anything that would be very different from the small ripples of the characteristic present in the entire band. Nevertheless, if the resonance can be removed by simple modification of the housing, why not? Returning to the impedance characteristic, I have just taken a few additional measurements.
imp_a.jpg

They differ in the tightening force of the woofer screws. The more tightly it is screwed, the higher the resonance frequency, so it clearly has something to do with the woofer installation. Is that the large (compared to the small enclosure) woofer opening weakened its stiffness? and it is restored to some extent by the woofer's plastic basket? Since the bracing used in the prototype has no good effect, is there any other simple remedy for that?
 
I think gated is gonna be hard since I only have a umik1 USB mic at the moment?
As far as I know, it is doable link. With USB mic you will have some latency variations but it's not very important when you measure whole system (and it's a bigger problem when measuring drivers separately for simulation purposes). But I've never tried tbh.
How do I make an impedance measurement with a sealed (PR) enclosure (I do have a Dayton DATS)?
Impedance measurements are also be possible with REW link
 
.....
How do I make an impedance measurement with a sealed (PR) enclosure (I do have a Dayton DATS)?
I think gated is gonna be hard since I only have a umik1 USB mic at the moment?
...

Unless I am missing something...
1) Hook the alligator clips to the speaker terminals and run DATS for the in-box impedance of the complete system - sealed, ported or PR
2) Gating just "windows" the farfield measurement to eliminate reflections, which limits your ability to measure low frequencies. Gating is done in your measurement program, for example REW. Doesn't matter if you have USB or non-USB mic. If you want the low frequencies then do a nearfield measurement of the woofer and merge the nearfield and farfield. This requires some extra work, but if you want to do it you should be able to find a few guides using Google.
 
Unless I am missing something...
1) Hook the alligator clips to the speaker terminals and run DATS for the in-box impedance of the complete system - sealed, ported or PR
2) Gating just "windows" the farfield measurement to eliminate reflections, which limits your ability to measure low frequencies. Gating is done in your measurement program, for example REW. Doesn't matter if you have USB or non-USB mic. If you want the low frequencies then do a nearfield measurement of the woofer and merge the nearfield and farfield. This requires some extra work, but if you want to do it you should be able to find a few guides using Google.
I only have the dats for a couple of weeks now and used them to measure free air parameters. Have to check the docs for speaker impedance.
I understood that USB mics have synchronization/timing issues that can mess up the gating but as @XMechanik said it might be unimportant for this measurement. I see what I can do next week.
 
and will this speaker do , return of the jedi , rancor real professional cinema THX levels with pressing bass so hard against the body
 
This looks really great, hard to believe the enclosure is made of scrapped outdoor facilities.
Those high frequency roll-offs seem a bit suspicious to me, but maybe I'm just not very familiar with MMM measurements. Have you measured both units? Are the results identical? Are you able to do a simple impedance measurements and a gated SPL on axis measurements?
Here are the impedance measurements, looks fine to me....
Also added some FR measurements when only a single driver was connected to the crossover. Plotted all drivers on one chart.
Those were taken at really close range, like 2cm. Don't mind the spl difference between the woofers because i didn't actually measure the measurement distance.
 

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These measurements look really good. The impedance characteristic is almost identical to the prototype, strangely you can't even see the resonance in the 300Hz region. The nearfield (2cm) measurement matches the Klippel NFS, so there is no reason to suspect problems with on-axis or any other characteristic. Honestly, when I read your post no. 320 I thought there might be a problem with the implementation. The measurements you attached don't seem to confirm this, and the difference compared to my perception seems to be just a matter of individual preferences. However it's still worth to perform 1m on-axis gated spl measurement just to confirm the balance between woofer and tweeter.
 
They differ in the tightening force of the woofer screws. The more tightly it is screwed, the higher the resonance frequency, so it clearly has something to do with the woofer installation. Is that the large (compared to the small enclosure) woofer opening weakened its stiffness? and it is restored to some extent by the woofer's plastic basket? Since the bracing used in the prototype has no good effect, is there any other simple remedy for that?
You might try placing some appropriately sized rubber o-rings or rubber washers between the underside of the screw head and the woofer basket.

In another forum, an experienced builder did some methodical studies of various cabinet and damping materials, bracing and related construction details impact on resonance, and observed that this "screw damping" had surprisingly significant effect.

Anyway, its an easy change to try.
 
These measurements look really good. The impedance characteristic is almost identical to the prototype, strangely you can't even see the resonance in the 300Hz region. The nearfield (2cm) measurement matches the Klippel NFS, so there is no reason to suspect problems with on-axis or any other characteristic. Honestly, when I read your post no. 320 I thought there might be a problem with the implementation. The measurements you attached don't seem to confirm this, and the difference compared to my perception seems to be just a matter of individual preferences. However it's still worth to perform 1m on-axis gated spl measurement just to confirm the balance between woofer and tweeter.
Maybe the 300hz is just a room mode. I'll try to do a gated measurement somewhere this week. I have a 2.7 meter ceiling height in my room. Would 1.3m distance from the first surface be enough for a proper measurement or do I need a larger space?
I guess the difference in HF spl measured is also an effect of the room don't you think? It matches how I perceived the speaker in room (less 'detail/air' compared to the salon). Near field experience might be different but I have not tried it yet.
 
I would opt that this type of enclosure reinforcement [cross bracing] does not have a big effect.
Since the bracing used in the prototype has no good effect, is there any other simple remedy for that?
@XMechanik take a look at this thread. I had great success using 12x30mm hardwood strips glued to the panels of a pair of JBL LSR305p speakers, with 10-20dB reductions in vibration as measured with an accelerometer. The audioholics finite element analysis linked in the thread shows why it works.

As far as I can tell, the problem with cross-bracing is that it is prone to flex in the brace. Window bracing is much better, but simple glued strips get close to window bracing with much less accuracy required in dimensions.

Here's the LSR305p result - compare green to green and orange to orange.

1731904708633.png
 
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Can someone help out with finding the parts on the europe market? Ideally Germany? I have none experience building speakers but would like to get started

Looks like awesome price/value!
 
This looks really great, hard to believe the enclosure is made of scrapped outdoor facilities.
Those high frequency roll-offs seem a bit suspicious to me, but maybe I'm just not very familiar with MMM measurements. Have you measured both units? Are the results identical? Are you able to do a simple impedance measurements and a gated SPL on axis measurements?
Many speakers from China have casings made from old gaming machines, furniture, business equipment, etc. Sometimes you can tell when you look inside. Of course, you can't see anything from the outside.
 
Can someone help out with finding the parts on the europe market? Ideally Germany? I have none experience building speakers but would like to get started

Looks like awesome price/value!
I ordered my parts on soundimports.eu. They had everything needed and I got the shipping for free to Czechia. Here is the cart:
There is one pair of coil missing (0,33mH) - they didn't have them in stock so I bought them elsewhere.
Screenshot 2024-11-21 at 11.23.49.png

btw, in hindsight, I would probably buy a thinner speaker wire, I think I bought a way too thick one
 
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