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The short answer is: EQ can fix it. (Wideband 0.4Q -7db @ 16khz etc)
Or maybe try inverting the tweeter polarity, see if that makes it better/worse.

The longer solution would start by importing your REW sweeps for each raw-driver into XSim and plugging in the T/S parameters for each driver, and modeling the crossover.
See if that sims reality.

If not, then it is probably a complex interaction between the woofer and tweeter and crossover, a resonant feedback loop of induction/capacitance of the driver coils, magnetic field flux backEMF and crossover attributes of the same.
To model this properly you'd need a WT2 and import those charts into XSim, then you'd probably have to play with the crossover component values to get it right.
They probably didn't do that when they designed it. That would be my guess.
 

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I'm not sure why you're spamming this on 3-4 different forums. Just call them. It could be a known issue already.

As I said, clearly it's not normal because folks would have been talking about it. The only other thing you could do is buy the Cnote crossover PCB's on ebay as those are pretty simple and hard to screw up. Then if you still have an issue it'd clearly be related to something in the chain.
 

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Discussion Starter #23
The short answer is: EQ can fix it. (Wideband 0.4Q -7db @ 16khz etc)
Or maybe try inverting the tweeter polarity, see if that makes it better/worse.

The longer solution would start by importing your REW sweeps for each raw-driver into XSim and plugging in the T/S parameters for each driver, and modeling the crossover.
See if that sims reality.

If not, then it is probably a complex interaction between the woofer and tweeter and crossover, a resonant feedback loop of induction/capacitance of the driver coils, magnetic field flux backEMF and crossover attributes of the same.
To model this properly you'd need a WT2 and import those charts into XSim, then you'd probably have to play with the crossover component values to get it right.
They probably didn't do that when they designed it. That would be my guess.

yeah, i can eq it out of existence, however what if someone is wrong? what if they did change something in the tweeter? what if they are shipping the wrong caps/resistors/inductors....this then seems like a problem worth fixing no? what if it's 100% my fault, certainly would like to know that to, but ignoring it across 3 completely independent speakers built wouldn't be giving back if there was an issue


I'm not sure why you're spamming this on 3-4 different forums. Just call them. It could be a known issue already.

As I said, clearly it's not normal because folks would have been talking about it. The only other thing you could do is buy the Cnote crossover PCB's on ebay as those are pretty simple and hard to screw up. Then if you still have an issue it'd clearly be related to something in the chain.

casting a wide net, what does it matter to you how many forums and folks i look to for an answer? thanks for furthering the discussion



and yes, i called them today to get the process of investigation started on their end as well



i think its the website. your graphs dont show either. i added a link above to the results.

https://imgur.com/a/Bdh8pYq

thanks i was able to see them on imgur, doesnt look like you have what i have, but can you change your graph limits to adjust the DB scaling to something like 45db low end to 110db top end?
 

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Here is a measurement of my older ND25FW-4 tweeters in a mock C-note baffle. With and without the C-note crossover on the tweeter. There is some lift to the top end with the crossover but obviously not nearly as much as you see in your measurements.

These tweeters are from I believe around 3-4 years ago, I have 4 of them and they all measure the same with that dip at the top end. So obviously there have been changes made the tweeters over the years. I had purchased those tweeters intending to use them in a design but haven't started that yet, looks like I may need to pick up a newer pair so I am not working with an out of date response.

When I last updated the crossovers on my Nexus designs I did so partially because some of the newer tweeters ND28 I purchased measured different then the older ones I had initially designed the speaker with. Unfortunately this seems to be a common occurrence with drivers from China.
 

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[/QUOTE]
thanks i was able to see them on imgur, doesnt look like you have what i have, but can you change your graph limits to adjust the DB scaling to something like 45db low end to 110db top end?[/QUOTE]

Can you give me a list of how that is done?
 

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In REW that is controlled by the Limits option at the top right. Also go into preferences and under the view tab uncheck "Use thick traces" which will result in the smaller more detailed trace lines.
 

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Here is a measurement of my older ND25FW-4 tweeters in a mock C-note baffle. With and without the C-note crossover on the tweeter. There is some lift to the top end with the crossover but obviously not nearly as much as you see in your measurements.

These tweeters are from I believe around 3-4 years ago, I have 4 of them and they all measure the same with that dip at the top end. So obviously there have been changes made the tweeters over the years. I had purchased those tweeters intending to use them in a design but haven't started that yet, looks like I may need to pick up a newer pair so I am not working with an out of date response.

When I last updated the crossovers on my Nexus designs I did so partially because some of the newer tweeters ND28 I purchased measured different then the older ones I had initially designed the speaker with. Unfortunately this seems to be a common occurrence with drivers from China.



https://imgur.com/a/7NJQ3en

I think this is what you were looking for.
Edit:eek:ops quoted wrong post/person but it wont let me change it now
 

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casting a wide net, what does it matter to you how many forums and folks i look to for an answer? thanks for furthering the discussion



and yes, i called them today to get the process of investigation started on their end as well
Just seems like a lot of effort for a pair of $100 speakers that one of two things are wrong: 1) either your crossover or 2) the components themselves. And one of those is out of anyone's control here.

Basically, until you find out what PE says or until they ship you some new components, everything else is just spinning your wheels.

The only one who can "further" anything at this point is PE. Not trying to be rude, but ultimately with their history of shipping components that weren't QC'd very well, that's where I'd hang my hat.
 

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Discussion Starter #29



https://imgur.com/a/7NJQ3en

I think this is what you were looking for.
Edit:eek:ops quoted wrong post/person but it wont let me change it now

awesome, thanks, looks like something changed for sure in the tweeter is my only conclusion


Just seems like a lot of effort for a pair of $100 speakers that one of two things are wrong: 1) either your crossover or 2) the components themselves. And one of those is out of anyone's control here.

Basically, until you find out what PE says or until they ship you some new components, everything else is just spinning your wheels.

The only one who can "further" anything at this point is PE. Not trying to be rude, but ultimately with their history of shipping components that weren't QC'd very well, that's where I'd hang my hat.

thanks, while yes, it's only 100 bucks, i'm actually in for 300+additional equipment as i have a two pairs + a center being built. so it's more than just 100. and honestly, it could be $20, i wouldnt care. you have to remember, i simply came looking to see if i did something wrong in my build. validation would be that, no, they are working as intended. however there isnt a single response curve posted (yet) that shows mine are working 'as expected', so before i give them off to someone to enjoy, i'd like to make sure they are done correctly. so this isnt a big investment of time taking some measurements, and asking some questions. and if maybe something changed in the design, they should post that so people can appropriately temper and set their expectations.


Here is a measurement of my older ND25FW-4 tweeters in a mock C-note baffle. With and without the C-note crossover on the tweeter. There is some lift to the top end with the crossover but obviously not nearly as much as you see in your measurements.

These tweeters are from I believe around 3-4 years ago, I have 4 of them and they all measure the same with that dip at the top end. So obviously there have been changes made the tweeters over the years. I had purchased those tweeters intending to use them in a design but haven't started that yet, looks like I may need to pick up a newer pair so I am not working with an out of date response.

When I last updated the crossovers on my Nexus designs I did so partially because some of the newer tweeters ND28 I purchased measured different then the older ones I had initially designed the speaker with. Unfortunately this seems to be a common occurrence with drivers from China.

based on my latest round of measurements, i'm going to have to conclude the tweeter did in fact change, so yes, i'd ensure to update your design and xover choices to account for it
 

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Discussion Starter #30
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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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
how long ago did you buy and build yours? Mine were purchased in January, assembled right away, and i didnt get around to installing the speakers until march or so. Then i finally finished them a couple of weeks ago.

I also do not have the capacitor mod. i would look to find someone who has the mod test theirs.
 

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Discussion Starter #34
Paul Carmody is on Twitter. Have you tried to ask him since he designed the speakers?

oh no, i hadn't, i keep getting the impression i've annoyed people with this topic. once i hear from PE that this is or isn't a change, and 100% not something i did in the build wrong, i'll reach out and see what he thinks


I have a set of C-Notes I bought pre-built (used), happy to take some measurements if you think it'd help.

i'm always open to more data on the topic, if you ahve the time it should would be helpful


how long ago did you buy and build yours? Mine were purchased in January, assembled right away, and i didnt get around to installing the speakers until march or so. Then i finally finished them a couple of weeks ago.

I also do not have the capacitor mod. i would look to find someone who has the mod test theirs.

the kits were purchased 2/4/19 (2x MTs) and 4/30/20 (1x MTM-center), and just recently put together (last week or so)


as for the cap mod, unfortunately it is on the woofer side of the circuit, but who knows. i have very limited xover experience. others have noted it shouldnt have had anything to do with that frequency range that is experiencing a bump
 
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