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Parts Express DIY C-Note Speaker Review

maxxevv

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#81
Any hardware store will sell runs of foam gasket tape in various density and thickness. Also you can use rope caulk which is very common and often used for this sort of thing. Do not use to thick of foam or to much rope caulk, you will bend the woofer frame trying to compress the material.
You can also use a think bead line of quality silicone caulk. Let that dry for awhile (half dry ) and then mount the woofer.
By the way the paper gasket is not that bad and really is prolly not the problem, paper is a great material in certain gasket applications.
Has anyone tried using o-rings as a gasket for those drivers instead ?
 
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#82
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?
But you would sacrifice the lower bass regions. Just aiming for a low f3 is [imho] very shortsighted in speaker construction. Especially if you consider boundary gain, it could be benificial to go for the earlier, but flatter drop in bass extension. And a lower tuning frequency limits the woofers excursion where you need it.
 
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ROOSKIE

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#83
Has anyone tried using o-rings as a gasket for those drivers instead ?
There is no reason not to. Anything that is normally used as a thin gasket that compresses a bit will work.
However note the driver has a paper o ring already built into the frame which is likely already enough but folks might want to experiment.
 

Rick Sykora

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#84
But you would sacrifice the lower bass regions. Just aiming for a low f3 is [imho] very shortsighted in speaker construction. Especially if you consider boundary gain, it could be benificial to go for the earlier, but flatter drop in bass extension. And a lower tuning frequency limits the woofers excursion where you need it.
Maybe but the designer made his call and is not just about the lower f3. The tuning change also eliminates the ugly 700 Hz port resonance too.

Let's see what he says.
 
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Francis Vaughan

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#85
There are probably great number of tweaks. One that I have played with, but have forgotten a lot of the quantitative results for, is to fill the port with straws. This doesn't change the port's main parameters much, adds some resistance, but can act to remove a lot of port noise. I remember the venerable Mission 770 used something similar.

I do like to get a reasonable amount of damping into any cabinet. It is useful to remember that for most of the frequencies involved the wavelength is much larger than the cabinet dimensions. There is no bouncing around of waves. There is just flow of air. Until you have wavelengths small wrt to the cabinet dimensions the cabinet is just being pressurised and evacuated. In this regime stuffing on the walls has less effect. There is of course energy right into quite high frequencies present - harmonic distortion can mean significant energy at quite small wavelengths. Good for hitting modes that one might have imagined were not going to be energised.
 

Rick Sykora

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#86
There are probably great number of tweaks. One that I have played with, but have forgotten a lot of the quantitative results for, is to fill the port with straws. This doesn't change the port's main parameters much, adds some resistance, but can act to remove a lot of port noise. I remember the venerable Mission 770 used something similar.

I do like to get a reasonable amount of damping into any cabinet. It is useful to remember that for most of the frequencies involved the wavelength is much larger than the cabinet dimensions. There is no bouncing around of waves. There is just flow of air. Until you have wavelengths small wrt to the cabinet dimensions the cabinet is just being pressurised and evacuated. In this regime stuffing on the walls has less effect. There is of course energy right into quite high frequencies present - harmonic distortion can mean significant energy at quite small wavelengths. Good for hitting modes that one might have imagined were not going to be energised.
Thanks for sharing! Brought back memories as I owned a pair of those Missions.

Forgot about the straw thing. Not sure I have enough around to try though. Not to mention the potential environmental catastrophe! :facepalm:
 
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#87
I have to admit, that I was pleasantly surprised by the performance of such a cheap DIY kit. I am into DIY for 1.5 years now, the loudspeaker in my avatar is the built for my living room. When I heard these loudspeakers I never turned back, sold happily my old B&W (CDM 7SE) for only 200€ without any regrets and currently are in the course of building the next kit (this time a Jeff Bagby design) for my apartment at work (where they will replace KEFs). So it is good to see, that even cheap kits may perform well (within reason), objectively. Curious to see more of those measurements, but my own speakers are a little on the large side to ship them to Amir, unfortunately.
 

ta240

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#88
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.
That sounds like a fun job. I'm a big fan of parts-express and the diy speaker kit listings are my grown up version of the Sears Christmas catalog :)
 

sychan

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#89
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 ;).
Shows how much I know about speaker design that I missed the obvious fact about it being a full wavelength! Thanks for the suggestions.

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.
@Winkleswizard posted results of testing with the damping and shortened port this morning, and it seems that with both tweaks, the resonances disappeared. Sounds like just lining the bottom half of the the interior with dampening might get rid of the resonances without effecting the base response, addressing the only criticism that Amir had in the listening tests.
 

Rick Sykora

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#90
Shows how much I know about speaker design that I missed the obvious fact about it being a full wavelength! Thanks for the suggestions.



@Winkleswizard posted results of testing with the damping and shortened port this morning, and it seems that with both tweaks, the resonances disappeared. Sounds like just lining the bottom half of the the interior with dampening might get rid of the resonances without effecting the base response, addressing the only criticism that Amir had in the listening tests.
Yes, as the designer stated, the damping material was not included due to the cost target. The lower f3 tuning may just have been missed or discounted for some other reason. He did mention the C-Notes were designed for near-wall use but would prefer the lower f3 myself. The Italian testing of the woofer shows a rise in distortion around 3 kHz, so seems more likely than the tweeter, but will check it out when I have time.
 
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Rick Sykora

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#91
Can confirm the rise in distortion around 3kHz is the woofer and my results are very comparable to Amir's originally posted measurement.

This is as I would expect as the woofer is at the higher end of its range and the tweeter is early on in its usable range. Make your own judgement on audibility. ;)

Still a very likable speaker for the price!
 
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sychan

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#92
Can confirm the rise in distortion around 3kHz is the woofer and my results are very comparable to Amir's originally posted measurement.

This is as I would expect as the woofer is at the higher end of its range and the tweeter is early on in its usable range.
There was some debate on the tech-talk forum about whether the crossover needed to filter out the breakup around 7k-8k, and ChrisP tested a crossover that snuffed out the residual breakup. He had a graph that overlaid the woofer response (yellow), the system response (blue) and the response of the woofer with the stock low pass filter (black).
c-note woofer response.jpg


It doesn't look like the woofer is near losing it at 3k, and in this graph of distortion from a customer review on Feb 2 2018, there isn't that bump in distortion that Amir found (even with the smoothing, you can those bumps at 700 and 900):
c-notegraph.jpeg


Here's the reviewer's comment: "I am impressed by these, they really have a decent low end and at least at the levels I use them low distortion. I have several pairs of good larger speakers but these hold there own and are very satisfying to listen too. I will include an REW measurement made at 1 meter 10 degrees. I did add a small amount of damping and pinched some old towel material between top of port tube and cabinet to reduce some port noise at the cabinet resonance about 280 Hz"

I wonder if something has changed since 2/2018?

[edit]

I found some measurements of the woofer's distortion and there is a big peak at around 3k:
cnote-woofer.png
 
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amirm

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Thread Starter #93
It doesn't look like the woofer is near losing it at 3k, and in this graph of distortion from a customer review on Feb 2 2018, there isn't that bump in distortion that Amir found (even with the smoothing, you can those bumps at 700 and 900):
We need to know his playback level. Here is my distortion measurement at low (2.83 volt input) level:
1587621885075.png


As you see, it looks like his. Part of the reason is the vertical scale being so compressed as was his.
 

Rick Sykora

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#94
[QUOTE="sychan, post: 380488,
..I found some measurements of the woofer's distortion and there is a big peak at around 3k...
[/QUOTE]

This would make 4 independent sources that clearly show the woofer distortion around 3kHz. Plenty for me! It is not the first or last driver that will have distortion - it is all a matter of the imperfections and tradeoffs in the driver design. Unlike the port resonance issue, this one is not likely to have a quick fix. If you cannot tolerate, then there are other designs. Even in speakers that cost 100 times more, you may find drivers that have comparable issues.

For a better understanding of why the test conditions matter and distortion profile matters, see this thread and notably this article:

https://www.audiosciencereview.com/...ely-is-a-sinad-of-96db-poor.12519/post-374581
 
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#95
I built a set of these about a month ago. I built them with additions without any previous experience with them, so i can't compare to vanilla C-notes.

Changes:
- Wooden dowl glued across the two side panels.
- .22uF cap mod.
- Denim added to three sides.
- Used a terminal plate.
- Shortened the port by 1/2 inch. Plan is to use as desktop speakers with a small sub.
- About 10g of polyfill.

1587668733452.png


Here they are minutes after finishing them. Threw them up on top of the DIY swan kit for a size comparison and a quick functional test.

1587668972825.png
 

maxxevv

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#96
I built a set of these about a month ago. I built them with additions without any previous experience with them, so i can't compare to vanilla C-notes.

Changes:
- Wooden dowl glued across the two side panels.
- .22uF cap mod.
- Denim added to three sides.
- Used a terminal plate.
- Shortened the port by 1/2 inch. Plan is to use as desktop speakers with a small sub.
- About 10g of polyfill.

View attachment 60061

Here they are minutes after finishing them. Threw them up on top of the DIY swan kit for a size comparison and a quick functional test.

View attachment 60063
I'm curious about the Swan/Hivi 3-way kit there. How do they compare with everything else you have ? (its subjective no doubt but its really about impressions at this point, whatever information is useful)
And what sort of amplification you used on them ?
 

sychan

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#97
It is not the first or last driver that will have distortion - it is all a matter of the imperfections and tradeoffs in the driver design. Unlike the port resonance issue, this one is not likely to have a quick fix. If you cannot tolerate, then there are other designs. Even in speakers that cost 100 times more, you may find drivers that have comparable issues.
The graph of the distortion at ~3khz was in thread on the tech-talk forum discussing replacing the stock Dayton DSA135-8 with a Fountek FW146, which would get rid of a lot of the woofer distortion, but also drive price from $100 to $175!
 
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#98
I'm curious about the Swan/Hivi 3-way kit there. How do they compare with everything else you have ? (its subjective no doubt but its really about impressions at this point, whatever information is useful)
And what sort of amplification you used on them ?
So far I haven't heard much from the C-notes and the Hivis are in a corner, so don't have a great listening space for either right now. Was getting ready to move before coronavirus hit. However, from where they're sitting the hivis sound better, mostly from the detailed mids coming from that big mid tweeter. I feel like the hivis are a bit choked in the low end when not paired with a sub, which I believe is from using the included foam for internal dampening. Looks like that foam takes up too much volume.

Using a Yamaha a-s701 since my other Yamaha died (blew it's internal fuse, power supply and rectifier checks out as well as the low power components, so I believe it's one of the final stage transistors) and none of the other amps I have power 4ohm speakers. Working on piecing together a tpa3255 amp in the mean time.
 

stevenswall

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#99
Makes me wonder if the HiVi DIY 3.1 has a better score or not. I nitpick it to death, and relegated them to a second living room, though they impressed me a ton when I first built them. (Going from Vizio TV speakers to it was incredible.) Based on the subjective review, these C notes sound like they may be better and cheaper.
 

stevenswall

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So far I haven't heard much from the C-notes and the Hivis are in a corner, so don't have a great listening space for either right now. Was getting ready to move before coronavirus hit. However, from where they're sitting the hivis sound better, mostly from the detailed mids coming from that big mid tweeter. I feel like the hivis are a bit choked in the low end when not paired with a sub, which I believe is from using the included foam for internal dampening. Looks like that foam takes up too much volume.

Using a Yamaha a-s701 since my other Yamaha died (blew it's internal fuse, power supply and rectifier checks out as well as the low power components, so I believe it's one of the final stage transistors) and none of the other amps I have power 4ohm speakers. Working on piecing together a tpa3255 amp in the mean time.
Did you use the provided packaging open cell foam? Mackie completely stuffs their HR824 with that stuff.

I used recycled denim on mine to try and get rid of some internal reflections, and used the "Perfectionist Crossover" that ScottS designed.

I always thought the midrange driver was the worst driver of the three, but come to think of it, most of my complaints are about treble issues (triangles are still too bright, even with the modified crossover taking the highs) and wanting more bass.
 
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