My first DIY

[eddantes]

Hello all.

Just wanted to share the completion of my first (non-kit) DIY. This forum and DIYAudio is the place where I learned the things that allowed me to do it. I just wanted to make a post to say - Thank You! I really enjoyed the process and I am greatful for the resources that ASR and DIYA made available.

I would like to specially thank Amir for this site and the patient, educational videos about all things audio. @napilopez for your awesome post about making quasi unechoic measurements. @kimmosto - for the amazing VituixCad. @Rick Sykora (and others) for all the build threads I followed over the years. This is a wonderful and supportive community and I apreciate being a part of it.

Measurements

Model

I have a very long way to go (directivity yikes), but I am proud of my first steps.

 

[VMAT4]

Wow, I'm impressed and jealous! Seriously! I'll give you a job well done on those!

 

[ChrisG]

Yeah, the directivity could use some work, but it's not the end of the world.

FWIW, I've ended up with similar before now:
I was converting a pair of Fostex PM04 to passive, because someone had removed the amplifiers previously.
I initially went for 2.2kHz 2nd-order HPF on the tweeter, which is a 16mm unit with basically-zero power handling.

On- and off-axis response was good, and it sounded decent.

.... Until I turned it up a bit. The sound became spitty and harsh at moderate levels. Culprit: harmonic distortion towards the bottom end (and just below) the tweeter's bandwidth. Remember, kids: a 12dB/octave acoustic slope is still constant-excursion as frequency decreases.

Next-best crossover involved a 3rd order HPF at 2.7kHz. On-axis was still fine (the woofer is pretty well-behaved), but the off-axis wasn't quite as nice.
This time, though, the tweeter stayed comfortable and composed at pretty impressive levels. The woofer became the limiting factor in output, particularly if there was much LF content.
Either way, though, the overload characteristics became much more tolerable. It didn't get harsh/spitty any more.


Do a bit of harmonic distortion testing before seeing if you can run that tweeter any lower. If you can get away with it, though, that's what I'd be looking to do.



Chris

PS - the cabinets look great. Well done.

 

[Timcognito]

Add a Sub, a center, place on ether side of big TV, toe them in a little, and then feel real proud. A very good first DIY.

 

[eddantes]

Those cabs are nice from far but far from nice, if y'all know what ima sayin... But, thank you.
I din't really go out to match drivers, they were just on sale and this was my first go so I was trying to be reasonable.

 

[Rick Sykora]

Those cabs are nice from far but far from nice, if y'all know what ima sayin... But, thank you.
I din't really go out to match drivers, they were just on sale and this was my first go so I was trying to be reasonable.

I think the cabinets look nice too! Without knowing more about the crossover and drivers, hard to offer much help though.

Did you baseline your measurements using a known speaker?

 

[eddantes]

Here's the crossover. Tymphany DX20BF00-4 and Tymphany 830656. Solen had them on sale... so.. I figured why not.

And yeah... When I was measuring I started with my M22 and compared against Spinorama.org. It looked reasonable----ish.

ish... Enough to suggest that, on balance, what I was measuring was reflecting reality.

 

[Rick Sykora]

Ok, on-axis is a start, but did you do a full spin of your M22? Are you using loopback/timing reference?

If so, the driver data should be solid. If you want, post the project and will see how directivity might be improved.

 

[eddantes]

Ok, on-axis is a start, but did you do a full spin of your M22? Are you using loopback/timing reference?

If so, the driver data should be solid. If you want, post the project and will see how directivity might be improved.

Hey, Rick. I did some off axis measurements +-15ish degrees horizontal and vertical. Non scientific, as I didn't take the time nor bother with a turntable (this will come for the next project). Infact, the above, is my second crossover, as the first was rather poor above the tweeter. And no - no loopback timing.

But, in general, I'm going put a fork in this one.

I started my second project - a small standmount speaker. Here, I'll be focusing on directivity. However... once again... the drivers I found on Kijiji (it's like craigslist) :-D ... So once again it's more an exercise of "making lemonade" rather than making the best speaker I can. I figure, I need to get a couple under my belt, before I spend any real money on this. Besides, I feel I need to learn how to match what I see in Vcad to what I will hear in real life. So, it doesn't matter too much if the result is less than ideal so long as it is measurable (objective). I'll start a thread on this project soon. In there I will start with a full spin of the M22 and will try to produce a CEA2034 chart.

P.S. Thanks so much for your kind offer of help!