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Parts Express DIY C-Note Speaker Review

Rick Sykora

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#63
Thanks @Juhazi for the advice. Might have saved me some work had I seen it sooner. In any case, I needed to bring my impedance measuring computer back online as it could be used for broader based testing. It took a bit longer than I hoped, but is working now. In any case, both the impedance measurement and the port measurement confirm the 700 Hz port resonance from the Bassbox sim. The sim does makes it seems less severe than the port measurement.

The next question was how to fix? Plugging the port, brings the f3 above 100 Hz. So much for that nice bass. The supplied port is a 2 piece one. I had an extra, so tried with the shorter (4") portion. I got mixed results. It lowered f3 a nice bit, but the port resonance had moved to around 1.6kHz with a narrower Q. Have not really given a listen, but gives you another option if you don't like or cannot do the eq approach.

I did try some other techniques for the other issues I noted earlier. If you are interested, watch for post in the build thread later today. I have to get some lunch and fresh air. :)
 
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ChrisP

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#64
I've been looking forward to a detailed review of the C-note for quite a while now. Thanks Amirm! (dang, you test alot of speakers!)

This is pretty much what I was expecting.

The 700 Hz peak is most likely a resonance, or combination of resonances. I'm not sure if Winkleswisard added any damping inside the enclosure, but I'm guessing not (no problem, I agree with testing the kit as it comes). Internally the cabinet is 10" high, which is just about 1/2 the wavelength of 700 Hz. I assume that is the majority of the issue, a standing wave can add a couple dB peak to vented enclosures. I recommend significant damping in any enclosure to keep that under control (It is not included in the kit just to keep cost down, $100 was a hard target to hit, lol). Also, the side panels have a resonance in that area, so that is adding to it a bit (just a little), adding a brace tying the sides together would help a little. Port resonance might add to it a little, but 700 Hz just seems higher than I would expect for a significant port resonance. You could stuff a sock in it, but you'll kill the bass... Nobody wants that.

I doubt the peak has much to do with a leak around the tweeter. It would be easy to check for that, just play a tone around the tuning frequency. About 40 Hz. You'll hear significant chuffing around the tweeter/woofer overlap if there is a leak. Pressure in the enclosure is highest at tuning, air will get out anywhere is can.

Speaking about the bass response, I'm glad that you are happy with it. The C-note is designed to be used near a wall, so that will add quite a bit of boost if you are looking for flatter low end response. But in my experience, extended low end is better than flatter low end, if you have to choose between the two (small speakers). Your brain is good at filling in dips in low frequenies, but there has to be something there to begin with. So, the C-note enclosure is not exactly optimum, more of an extended bass shelf alignment (EBS). Plus, that keeps excursion under control for better power handling (like amirm said, "I could barely see it moving"). I'm not a fan of speakers tuned to 50 Hz or higher unless it is specifically designed to be used in a system with a subwoofer. That is just a recipe for over-excursion disaster... Just go sealed at that point.

About the higher distortion at the crossover. Yeah, the 3,000 crossover is really pushing the limits of that little tweeter. It was a compromise to get better vertical dispersion. There were many crossover designs, some had crazy flat response, but had many more parts ($$$) and in side by side listening tests the difference was negligible.

The C-note was fun to design... An abosute exercise in simplified and getting that most bang for your buck.

Oh, about the gorilla glue crossover thing. We send a lot of speaker to trade shows and crossover parts alway break loose in shipping (inductors mostly). No matter how well we mounted them (zip ties, screws, even epoxy), the shipping companies alway found a way. Completely embedding the crossovers in Gorilla glue seems to have fixed the issue. I even dropped a Blast Box down a flight of stairs with no issue (well, with the crossover at least, lol). Plus, it...uh... helps with microphonics? Yeah, that's it, microphonics!

Thanks again for the review Amirm! I'm glad you were satisfied with it.
 

edechamps

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#65
How do you use the Loudspeaker Explorer? I don’t get it.
The first thing you need to do is click "Runtime" → "Run All" to run the notebook. Then you can change settings (e.g. select different speakers), and every time you do that, you need to click "Run All" again to apply the changes.

This is explained in the introduction at the beginning of the notebook. Let me know if something isn't clear to you and I'll try to improve it.
 
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#66
Spray paint the mdf black and double the price
I have painted speakerkits with a roller, two layers of primer, two layers of alkyd paint. The bathroom was a low dust environment
(don't dry laundry there) and it had a fan so no paint fumes in the rest of the apartment.
Nowadays I prefer water-based paints.
 

Billy Budapest

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#68
The first thing you need to do is click "Runtime" → "Run All" to run the notebook. Then you can change settings (e.g. select different speakers), and every time you do that, you need to click "Run All" again to apply the changes.

This is explained in the introduction at the beginning of the notebook. Let me know if something isn't clear to you and I'll try to improve it.
Yeah, I just didn’t understand the explanation and didn’t see Runtime or Run All. I will try again!
 

Trouble Maker

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#69
How good/bad of an idea would it be to try to cutout the area in the wave-guide where the mid-woofer is to also flush mount the mid-woofer?
Could it have much of an effect, or is this outside of the critical area of the wave-guide? I would hope the later is true or having the mid-woofer basket there is a problem.
I would think someone with half-way decent skills in this area (woodworking, etc) could do it with a router/jig saw/scroll saw/dremmel and either a steady hand or making a guide.
Everyone is talking about putting a nice finish on these and I can't help but think spending the time and cost of a nice finish would be worthless without the mid-woofer also being flush-mount. Without either of these this speaker is not good, for me or I imagine many people, beyond the garage.
 

xarkkon

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#71
I've been looking forward to a detailed review of the C-note for quite a while now. Thanks Amirm! (dang, you test alot of speakers!)

This is pretty much what I was expecting.

The 700 Hz peak is most likely a resonance, or combination of resonances. I'm not sure if Winkleswisard added any damping inside the enclosure, but I'm guessing not (no problem, I agree with testing the kit as it comes). Internally the cabinet is 10" high, which is just about 1/2 the wavelength of 700 Hz. I assume that is the majority of the issue, a standing wave can add a couple dB peak to vented enclosures. I recommend significant damping in any enclosure to keep that under control (It is not included in the kit just to keep cost down, $100 was a hard target to hit, lol). Also, the side panels have a resonance in that area, so that is adding to it a bit (just a little), adding a brace tying the sides together would help a little. Port resonance might add to it a little, but 700 Hz just seems higher than I would expect for a significant port resonance. You could stuff a sock in it, but you'll kill the bass... Nobody wants that.

I doubt the peak has much to do with a leak around the tweeter. It would be easy to check for that, just play a tone around the tuning frequency. About 40 Hz. You'll hear significant chuffing around the tweeter/woofer overlap if there is a leak. Pressure in the enclosure is highest at tuning, air will get out anywhere is can.

Speaking about the bass response, I'm glad that you are happy with it. The C-note is designed to be used near a wall, so that will add quite a bit of boost if you are looking for flatter low end response. But in my experience, extended low end is better than flatter low end, if you have to choose between the two (small speakers). Your brain is good at filling in dips in low frequenies, but there has to be something there to begin with. So, the C-note enclosure is not exactly optimum, more of an extended bass shelf alignment (EBS). Plus, that keeps excursion under control for better power handling (like amirm said, "I could barely see it moving"). I'm not a fan of speakers tuned to 50 Hz or higher unless it is specifically designed to be used in a system with a subwoofer. That is just a recipe for over-excursion disaster... Just go sealed at that point.

About the higher distortion at the crossover. Yeah, the 3,000 crossover is really pushing the limits of that little tweeter. It was a compromise to get better vertical dispersion. There were many crossover designs, some had crazy flat response, but had many more parts ($$$) and in side by side listening tests the difference was negligible.

The C-note was fun to design... An abosute exercise in simplified and getting that most bang for your buck.

Oh, about the gorilla glue crossover thing. We send a lot of speaker to trade shows and crossover parts alway break loose in shipping (inductors mostly). No matter how well we mounted them (zip ties, screws, even epoxy), the shipping companies alway found a way. Completely embedding the crossovers in Gorilla glue seems to have fixed the issue. I even dropped a Blast Box down a flight of stairs with no issue (well, with the crossover at least, lol). Plus, it...uh... helps with microphonics? Yeah, that's it, microphonics!

Thanks again for the review Amirm! I'm glad you were satisfied with it.
Just to confirm, are you Chris Perez the designer of the speakers? Awesome to have you come by to add in your views and also to address the 700hz issue!

What are you using to dampen your speakers? I got the 1/2 inch sonic barrier acoustic foam off Parts Express and am not sure if that would suffice.
 

sychan

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#72
I've been waiting to see this review too! Thanks, Amir and Winkleswizard for making this happen.

I've been looking forward to a detailed review of the C-note for quite a while now. Thanks Amirm! (dang, you test alot of speakers!)
[snip]
The 700 Hz peak is most likely a resonance, or combination of resonances. I'm not sure if Winkleswisard added any damping inside the enclosure, but I'm guessing not (no problem, I agree with testing the kit as it comes). Internally the cabinet is 10" high, which is just about 1/2 the wavelength of 700 Hz. I assume that is the majority of the issue, a standing wave can add a couple dB peak to vented enclosures. I recommend significant damping in any enclosure to keep that under control (It is not included in the kit just to keep cost down, $100 was a hard target to hit, lol). Also, the side panels have a resonance in that area, so that is adding to it a bit (just a little), adding a brace tying the sides together would help a little.

I think its amazing that someone involved in the design comments on a review, and admits that they did the best they could for the target cost - as well as providing useful advice on improvements. So it sounds like significant damping on the bottom and back panel up to where ever your binding posts are, as well as a dowel cross brace?

The C-Note MTM chart shows ~5db bumps at 700 and 900, they look milder than the ones on the C-Note, but wouldn't the 20" length of the C-Note MTM would just move the resonances to 1400? What other suspects are there for resonances that a DIYer could do in the build?
 

ChrisP

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#73
Just to confirm, are you Chris Perez the designer of the speakers? Awesome to have you come by to add in your views and also to address the 700hz issue!

What are you using to dampen your speakers? I got the 1/2 inch sonic barrier acoustic foam off Parts Express and am not sure if that would suffice.
Yep, the C-note is one of mine. I am the speaker building product line manager at Parts Express, I have a hand in a lot of our kits.

The 1/2" sonic barrier will work great. Line all walls. A lot of people think that 1/2" material won't do much, but keep in mind that the sound waves are bouncing around a lot and at all angles. So after a few reclections at odd angles sound waves will have passed through a buch of material and will attenuate quickly. Everyone worries about the first reflection, but you can never add enough material to really make any significant difference to the first reflection at the frequencies that the most noticable enclosure resonances will occur. You just want to make them decay faster, dont bother trying to eliminate them (well, maybe in a really good transmission line design).

Heck, I usually just add some lightly teased Acousta-Stuf, fill the enclosure about 1/2 way. But really, the 1/2" Sonic Barrier will be much more effective and won't affect tuning enough to worry about. Plus, the adhesive is so aggressive on that stuff it will couple to the walls enough to even lower the panel resonances a little (not that it is a huge issue, but better is always better). After the adhesive cures (I recently learned that the adhesive actually cures in about 12 hours, who knew?) it will actually pull off layers of the MDF if you try to remove it! Seriously sticky stuff!

-Chris P
 

ChrisP

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#74
How good/bad of an idea would it be to try to cutout the area in the wave-guide where the mid-woofer is to also flush mount the mid-woofer?
Could it have much of an effect, or is this outside of the critical area of the wave-guide? I would hope the later is true or having the mid-woofer basket there is a problem.
I would think someone with half-way decent skills in this area (woodworking, etc) could do it with a router/jig saw/scroll saw/dremmel and either a steady hand or making a guide.
Everyone is talking about putting a nice finish on these and I can't help but think spending the time and cost of a nice finish would be worthless without the mid-woofer also being flush-mount. Without either of these this speaker is not good, for me or I imagine many people, beyond the garage.
It would be fairly easy to recess the woofer into the tweeter with just a router and a jig. Just mount the tweeter, mask it off, and run the router right through it along with the wood (it's just plastic). It wouldn't hurt anything, just tilt the vertical response down a tiny little bit (the drivers have incredibly good time alignment as it, but that really dosen't mean very much in the whole scheme of things). It might actually smooth out the response through the cross over region a little since there will be no diffraction from the frame. So I say go for it!
 
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#75
One easy upgrade soundwise is to paint all the mdf panels on the inside of the box with wood-glue. Mdf leaks air if its not painted .
You can also use 50% glue and 50% water, mix it together and paint the outside of the box. In that way you have sealed the cabinet ( no need to paint the inside ) and you have a good prime on the panels that you can paint with your favorite colour. In that way you only need one sort of colour.
 
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ChrisP

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#76
I've been waiting to see this review too! Thanks, Amir and Winkleswizard for making this happen.




I think its amazing that someone involved in the design comments on a review, and admits that they did the best they could for the target cost - as well as providing useful advice on improvements. So it sounds like significant damping on the bottom and back panel up to where ever your binding posts are, as well as a dowel cross brace?

The C-Note MTM chart shows ~5db bumps at 700 and 900, they look milder than the ones on the C-Note, but wouldn't the 20" length of the C-Note MTM would just move the resonances to 1400? What other suspects are there for resonances that a DIYer could do in the build?
Well, 20" is pretty much a full wavelength of 700 Hz (even worse), and the height and depth is a half wavelength of 900 Hz (even worse)... Gee, now I'm secong guessing the dimensions of the C-note center, :facepalm: lol. Just kidding ;). Originally I had something that had more "optimal" dimensions, but it just looked too bulky for a center channel (there is something to "golden ratio" designed enclosures, but they just don't look good to me unless they are turned on thier side and it was just so deep)...plus the current cabinet results in less waste from the wood shop, so it's a little cheaper to make (seriously pinching pennies on these speakers). Just line all the walls with any decent damping material and those peaks will drop quite a bit. Less significant resonances at 1,400 Hz are getting out, a port is a low pass filter with a shallow slope and it has more attenuation up that high... Every octave helps... Ok, so I just looked at the response again... and that might explain the bump in the 1,500 Hz area...

We measure all out kits designed in house with only the parts supplied, just to be fair.

So, I suggest decent damping material in all enclosures. Even if you just add a couple handfulls of wool or Acousta-Stuff to the cabinets (standard pillow stuffing polyfill and dayton batting is not very effective, just for the record). Lining the walls with something like fiberglass (itchy), Ultra Touch denim (not itchy), or the self adhesive Sonic Barrier (recommended, but keep in mind, I am biased:cool:) is always the best option. Even cheap open cell foam is pretty darn effective, not great but it works.

-Chris P
 

JohnBooty

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#77
I'm a big proponent of DIY kits. Great gateway into the hobby. Arguably the best way to get high quality sound for cheap if you're a beginner.

I have read a LOT of testimonials for whom C-Notes and Overnight Sensations were an excellent gateway drug. :cool:

(Scouring Craigslist and estate sales for deals is obviously a great way too, but you need to know what you're looking for... and is often more time-consuming than a weekend DIY build IMO. Plus depending on where you live, it might not be a great idea.)

Kind of a messy assembly video. A PCB for the crossover would be nice. Or use terminal strips for electrical connections for a neat job.
The C-Notes kit and assembly video are aimed at absolute beginners.

Remember, there are a lot of people who are potentially interested in the DIY hobby but are too intimidated to give it a shot.

Accordingly the video shows the fastest way to achieve a working build for absolute beginners.

That's why I think it's great.

The assembly video is not going to dissuade anybody from doing a more professional build, if that's what they want. People who are interested in more professional builds will seek out that information on their own. That video is for people who are wondering if they should dip their toes into the pool or not.
 

Trouble Maker

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#78
It would be fairly easy to recess the woofer into the tweeter with just a router and a jig. Just mount the tweeter, mask it off, and run the router right through it along with the wood (it's just plastic). It wouldn't hurt anything, just tilt the vertical response down a tiny little bit (the drivers have incredibly good time alignment as it, but that really dosen't mean very much in the whole scheme of things). It might actually smooth out the response through the cross over region a little since there will be no diffraction from the frame. So I say go for it!
That's great to hear!

I will say after looking at some pictures of finish product on PE website I might have prejudged a little harshly. The black finish on the fronts of many seems to hide the non-flush mount woofer pretty well. I would still personally want to flush mount it, but for a beginner it the stock kit should work great!

It seems like there were a few things you would have wanted to do, but couldn't due to cost constraints. Where there any conversations about making a C-Note+ kit or add-on for those extra parts e.g. damping materiel? Everyone just got their stimulus checks and need somewhere to spend them!
 

xarkkon

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#79
Yep, the C-note is one of mine. I am the speaker building product line manager at Parts Express, I have a hand in a lot of our kits.

The 1/2" sonic barrier will work great. Line all walls. A lot of people think that 1/2" material won't do much, but keep in mind that the sound waves are bouncing around a lot and at all angles. So after a few reclections at odd angles sound waves will have passed through a buch of material and will attenuate quickly. Everyone worries about the first reflection, but you can never add enough material to really make any significant difference to the first reflection at the frequencies that the most noticable enclosure resonances will occur. You just want to make them decay faster, dont bother trying to eliminate them (well, maybe in a really good transmission line design).

Heck, I usually just add some lightly teased Acousta-Stuf, fill the enclosure about 1/2 way. But really, the 1/2" Sonic Barrier will be much more effective and won't affect tuning enough to worry about. Plus, the adhesive is so aggressive on that stuff it will couple to the walls enough to even lower the panel resonances a little (not that it is a huge issue, but better is always better). After the adhesive cures (I recently learned that the adhesive actually cures in about 12 hours, who knew?) it will actually pull off layers of the MDF if you try to remove it! Seriously sticky stuff!

-Chris P
Thanks again for dropping by and sharing. If only more manufacturers did the same!
 

Rick Sykora

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#80
Well, 20" is pretty much a full wavelength of 700 Hz (even worse), and the height and depth is a half wavelength of 900 Hz (even worse)... Gee, now I'm secong guessing the dimensions of the C-note center, :facepalm: lol. Just kidding ;). Originally I had something that had more "optimal" dimensions, but it just looked too bulky for a center channel (there is something to "golden ratio" designed enclosures, but they just don't look good to me unless they are turned on thier side and it was just so deep)...plus the current cabinet results in less waste from the wood shop, so it's a little cheaper to make (seriously pinching pennies on these speakers). Just line all the walls with any decent damping material and those peaks will drop quite a bit. Less significant resonances at 1,400 Hz are getting out, a port is a low pass filter with a shallow slope and it has more attenuation up that high... Every octave helps... Ok, so I just looked at the response again... and that might explain the bump in the 1,500 Hz area...

We measure all out kits designed in house with only the parts supplied, just to be fair.

So, I suggest decent damping material in all enclosures. Even if you just add a couple handfulls of wool or Acousta-Stuff to the cabinets (standard pillow stuffing polyfill and dayton batting is not very effective, just for the record). Lining the walls with something like fiberglass (itchy), Ultra Touch denim (not itchy), or the self adhesive Sonic Barrier (recommended, but keep in mind, I am biased:cool:) is always the best option. Even cheap open cell foam is pretty darn effective, not great but it works.

-Chris P
Hi Chris!

Welcome to ASR and thanks for sharing your thoughts and time! Hope all is well down in Dayton. I really do appreciate what it takes to meet the price/performance you have in the C-Note.

While agree some internal damping is good practice, get that it would add to the cost. My Bassbox sim of the C-Note suggests you would get rid of the 700 Hz port resonance by shortening the port to 4". You would also get a much lower f3 of 68 Hz. Along with reducing a step in the build (no need to glue the port), you gain more bass extension. Sounds like a win-win.

Any reason you would not recommend tuning to the lower f3?
 
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