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Parts Express DIY C-Note Speaker Review

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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.
I used the perfectionist crossover and the included foam. The denim that i used in the C-notes (pic above) was originally meant to go in the Hivis but decided that i was changing too much and i didn't have any way of backing up one over the other. The crossover mod has simulations behind it where i couldn't come up with any reason why the denim would be better than the foam. Also, apart from the included vinyl the kit didn't seem to be taking any shortcuts, so it seemed logical to trust the designer more than a whim.
 

stevenswall

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I used the perfectionist crossover and the included foam. The denim that i used in the C-notes (pic above) was originally meant to go in the Hivis but decided that i was changing too much and i didn't have any way of backing up one over the other. The crossover mod has simulations behind it where i couldn't come up with any reason why the denim would be better than the foam. Also, apart from the included vinyl the kit didn't seem to be taking any shortcuts, so it seemed logical to trust the designer more than a whim.
I think the designer intended for polyfill to be used... The fluffy stuff. When I looked up that vs recycled denim the denim seemed more effective at dampening sounds, which at the time I thought was the point. It also seemed closer to some JBL disassembly video that showed dampening material lining the sides, though now I've listened to JBL LSR speakers and probably wouldn't look at anything besides the waveguide as a good thing. I'm not sure that packing foam was intended to do in there but I may be wrong.

In any case, now I think the purpose is to make the box seem larger by stuffing it, and I'm not sure what works best for that. Wouldn't want poly fluff coming out in the air gap between the phase plug and woofer diaphragm, and the packing foam would be closer to stuffing while avoiding stuff coming out.
 
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Hmmm, these look like the Murphy Blasters from about 15 years ago that I built for my son. It was an SS 8513(?) tweeter with a Parts Express woofer, used a slight overlap as in the picture, but in a pre-built cabinet they used to sell. He still uses them, with a T-amp built into a smoked salmon box from the Pacific NW. I don't remember all the details but likely I have them somewhere.
 

xarkkon

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Finally put together my first diy speakers, the C Notes! Yay! Really enjoyed the build process, but made a whole truck load of mistakes.

What's everyone using to run them with? I'm thinking of getting a desktop amp to hook them up to my PC setup, replacing my Edifier 1280s.

1587867801773.png
 

Head_Unit

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Finally put together my first diy speakers, the C Notes! Yay! Really enjoyed the build process, but made a whole truck load of mistakes.
Building speakers is like golf, amazing that an activity so full of mistakes is so addictive! :D
Now, tell us about the finish on the front and the sides, cuz they look really nice.
 
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Head_Unit

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Any reason you would not recommend tuning to the lower f3?
Just aiming for a low f3 is [imho] very shortsighted in speaker construction. Especially if you consider boundary gain
Yup. I met Dick Small once in Indiana and we talked about that; he just chose -3 dB because it was mathematically convenient for his thesis and "half" seemed significant. Understand also this was before Allison had published work on boundary reinforcement http://www.aes.org/e-lib/browse.cfm?elib=2760. We didn't get into the discussion much but vaguely agreed the -6 or -10 dB points were probably more significant.
 

xarkkon

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Building speakers is like golf, amazing that an activity so full of mistakes is so addictive! :D
Now, tell us about the finish on the front and the sides, cuz they look really nice.
Thanks! Great thing about photos are that they help to hide the imperfections... Heh heh

Vivid vinyl for the sides and back, Rustoleum hammered black spray paint for the front.
 

Rick Sykora

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Will be interested to see if Parts Express makes any improvements to the C-Notes or just replaces them off hand...

I have one of their earlier kits and it seemed to get a comparable reception in the DIY community. Eventually it was just discontinued and not really replaced. Similar experiences with their finished cabinets. They were pretty good while they lasted (Dennis Murphy and others used them), but they suddenly dried up without a clear replacement (or explanation) either. Now the CBT24 kit is gone without any word either.

As I mentioned to someone else that is getting into DIY, you are your own warranty repair, so I buy some replacement drivers for any speaker I intend to keep. While PE has some great deals and service, strategic planning does not appear to be a core competence. Get the deals while the getting is good, but they may not be around tomorrow! :oops:
 
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I think the designer intended for polyfill to be used... The fluffy stuff. When I looked up that vs recycled denim the denim seemed more effective at dampening sounds, which at the time I thought was the point. It also seemed closer to some JBL disassembly video that showed dampening material lining the sides, though now I've listened to JBL LSR speakers and probably wouldn't look at anything besides the waveguide as a good thing. I'm not sure that packing foam was intended to do in there but I may be wrong.

In any case, now I think the purpose is to make the box seem larger by stuffing it, and I'm not sure what works best for that. Wouldn't want poly fluff coming out in the air gap between the phase plug and woofer diaphragm, and the packing foam would be closer to stuffing while avoiding stuff coming out.
I am the designer of the HiVi DIY 3.1 crossover mods. I don't want to derail this C Note thread with too much about that design, but would be happy to discuss any aspects in a separate thread.
 

xarkkon

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@Winkleswizard Oh dear, I hadn't realised that they removed the CBT24! It wasn't a design I was going to get into (it costs a whole lot of ship THAT many drivers over to Asia...) but liked the idea that they had a couple of "This is serious business" kind of kits to aspire towards.

Aye, can't expect much support with DIY gear, but I suppose most DIYers know what we're getting ourselves in to :) Can't think of many DIY kits that have had long term vendor support. Maybe Bottlehead?
 
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For kits with longevity, the Parts Express BR-1 just seems to stay around forever. It's been available for at least 15 years now. I don't understand why it is nearly double the cost of the C-Note...

I look at the C-Note as an interesting benchmark for DIY projects. It is a complete kit for 100 USD as the name implies. For that price, you get a pair of flat pack cabinets very similar to blank ones Parts Express sells for $50/pair. A pair of the woofers is another $50. The woofers make decent bass in that 7 liter (approximately) enclosure. The tweeters are $40 and have small waveguides that should at least help some with directivity. Add in the crossover components (about $60 retail I am guessing), port tubes, binding posts and the kit is an obvious value and challenging for the DIY'er to compete with. The speaker preference score vs. price chart illustrates that fact.

If I were just picking out equivalently priced drivers, I think one could do better, but one would need to do considerably better given the level of discount for the C-Notes. I would be confident putting my Mercury project up against it (7L cabinet, HiVi M5n woofer, Vifa BC25SC06-04 tweeter). Drivers are actually $25 cheaper, but crossover cost probably gives that advantage back. Reviewing my bill of materials, I would be at about $205 with flat pack cabinets. There are a few other woofers that could produce similar bass extension in the same enclosure that might allow a simpler crossover, but it's difficult to envision getting below $150/pair including the cabinets without major concessions in sound quality.
 
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hey all, just finished two pairs of cnotes and having an issue

seem to be getting a hf rise around 7k+, really weird

i've double and tripled checked my crossovers (did the .22 cap mod), but they look like they fit the design to a T

i can reproduce these measurements on 3 of the 4 i have built (haven't assembled the 4th entirely to check)

for the life of me cant figure out what is going on, not getting much help on the PE forum as well

thoughts?

individual drivers jpg: that has a full assembled speaker measurement, just the woofer w crossover, just the tweeter with crossover, and a random just tweeter w no crossover (at a -24dbFS to normalize the result, whereas the rest were done at -12dbFS)

raw drivers jpg: a full speaker, and then a raw woofer and tweeter, no crossover

clearly the xover is either adding this 'push', or perhaps not doing enough to 'pull' it down

thoughts?
 

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sychan

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hey all, just finished two pairs of cnotes and having an issue
...
I saw that you had asked about this on AVSForum and also on the Parts Express Tech-Talk. I think Tech-Talk is really your best bet, as would be contacting Parts Express directly.
 

BYRTT

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.....thoughts?.....
Overlaid to ASR spinorama below failure could look be two things 1) in REW microphone calibration file is loaded for raw tweeter but not loaded for filtered tweeter and summed system 2) some used component in filter or tweeter itself is not up to spec or by acident wired a wrong way.

datrumole_2.PNG
 

Rick Sykora

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hey all, just finished two pairs of cnotes and having an issue

seem to be getting a hf rise around 7k+, really weird

i've double and tripled checked my crossovers (did the .22 cap mod), but they look like they fit the design to a T

i can reproduce these measurements on 3 of the 4 i have built (haven't assembled the 4th entirely to check)

for the life of me cant figure out what is going on, not getting much help on the PE forum as well

thoughts?

individual drivers jpg: that has a full assembled speaker measurement, just the woofer w crossover, just the tweeter with crossover, and a random just tweeter w no crossover (at a -24dbFS to normalize the result, whereas the rest were done at -12dbFS)

raw drivers jpg: a full speaker, and then a raw woofer and tweeter, no crossover

clearly the xover is either adding this 'push', or perhaps not doing enough to 'pull' it down

thoughts?
Please post pics of your crossovers.

Also, do you have the ability to measure components values?
 
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Please post pics of your crossovers.

Also, do you have the ability to measure components values?
i have a multimeter, however all crossovers are completed, glued to bread boards, and soldered. clearly should have tested one before i went all in, but i was very confident i connected them 100% correctly. i double and tripled checked the diagram when laying it out

so it will be difficult to get precise measurements of individual components

pics of boards below

Overlaid to ASR spinorama below failure could look be two things 1) in REW microphone calibration file is loaded for raw tweeter but not loaded for filtered tweeter and summed system 2) some used component in filter or tweeter itself is not up to spec or by acident wired a wrong way.
thanks, i believe the calibration file is properly being used. i've verified the configuration is set in REW, and am not closing the application between measurements, so it's not being 'undone'. as for the second one, yes, i'm posting in hopes to figure out what that could be. the people who have done the simulations of the crossover haven't been able to tell me that if someone was miswired, id be seeing this response out of teh speaker. so i'm hopeful it is something i messed up, just dont know what that would be, nor could someone point me in teh right direction

I saw that you had asked about this on AVSForum and also on the Parts Express Tech-Talk. I think Tech-Talk is really your best bet, as would be contacting Parts Express directly.
thanks, yeah, been on a few different forums to get some answers for sure
 

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well, so here is my final post before i leave it in the capable hands of PE to determine the outcome

my only drawn conclusion is in fact that the tweeter design has changed

i think the smoking gun for my conclusion is the posted response of the c-note center channel, which upon further inspection, has the exact rise i'm seeing in my MT versions as well, HF rise starting at 7khz

below are the latest measurements, taken at 1m, with my denon 2310ci (not my tp22 which was exaggerating the lift) measured with a umik1

thanks for everyone who lent a helping hand. not sure if my findings may trigger a small update to the design or not to pull the response down, but i think PE should update the posted curves so people can be sure to compare it to the proper ones before they assume something is wrong
 

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DreenSap

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When did you purchase? I bought a pair in the past month, late april, and I'm not seeing anything with my silly little iMM-6. I did have to send the woofer back because one of the lead wires was twice as long as the other.
Any visible differences physically?
 
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When did you purchase? I bought a pair in the past month, late april, and I'm not seeing anything with my silly little iMM-6. I did have to send the woofer back because one of the lead wires was twice as long as the other.
Any visible differences physically?
oh nice, i hadnt ever really seen this mic, looks pretty slick for 20bucks

the MTs were purchased 2/4/19 (edited), the MTM (center) was 4/30/20

i had to send two woofers back with warped basksets as well, QC on these parts aren't exactly great
 
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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.
Ah, that explains it. I'm working on a DIY build right now using the DSA145 as the bass driver, and the measured response in the enclosure (which is around the same size as the C-Note) suggests that a 2mH series inductor and 7.5 uF shunt cap would be required to flatten the response from 100 Hz to 1.5 kHz (where is starts handing off to the tweeter. Then I remembered that you used this woofer in your C-Note design so I checked on the x-over you came up with and it was like... hmm. This would explain why the reviewer observed the "recessed" bass response, but of course if the speaker is designed to be used close to a wall, boundary gain will boost that up quite nicely, and the extra 2 or so dB of overall sensitivity should make it a little easier to drive with smaller amps. My build however is likely to be used quite a bit away from the wall, so I've got to cut out a bit more of that baffle step.

The distortion rise around 3 kHz is definitely a "feature" of the DSA135. It shows up in all my measurements, though crossing over at 3 kHz or below reduces its appearance in the graphs significantly. As for audibility, it seems to primarily odd-order, which means the first harmonic shows up around 9 kHz. I've tried listening for it with music playing, and I can't hear it. The big peak in the woofer's output near that frequency is much more audible, and that can be killed by an appropriately-sized shunt cap across the woofer's inductor.

As for the vent's 700 Hz resonance? I dodged that issue by using a passive radiator in my design, as Dayton sells a PR that's basically identical to the DSA135, sans magnet and coil of course. It does tune the box a bit lower than I'd like it to though. However, if I was going to go with a vented alignment, I'd model the enclosure in Hornresp (which can now do offset-driver, offset-vent sims) and see if there's a way to locate the vent so that the first (and usually most problematic) resonance is cancelled out. I wouldn't be surprised if that ends up being dead center of the rear baffle...
 
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