maybe it does sound better at louder SPL
and all is as we know relative
his real problem is that it sounds muffled at low SPL
a very clear indication of a phase issue
the focus on distortion is wrong
distortion does not appear to be his problem, since he is asking for more 😀
noone knows much about his speaker crosssover
btw, I hope Lynn Olson is ok with having his post being dragged over here from another thread 😕
and all is as we know relative
his real problem is that it sounds muffled at low SPL
a very clear indication of a phase issue
the focus on distortion is wrong
distortion does not appear to be his problem, since he is asking for more 😀
noone knows much about his speaker crosssover
btw, I hope Lynn Olson is ok with having his post being dragged over here from another thread 😕
Why should he mind me quoting his wise words? I credited him. 🙂
I love these threads where the OP finally reveals his circuit on page 4 and day 2. How long, O Lord, How Long? 🙄
So we actually have an MTM crossing over around 2kHz, it seems.
Visaton publish a Boxsim projekte file for something similar called the couplet/. They go for 2.5kHz with the poorer G20SC tweeter. It needs quite a lot of work for the KE25SC.
MTMs have unexpected problems in balancing the sound:
Antti Louhivaara said:
But that's another topic. I've got work to do. 🙂
For reference, Klang + Ton measured the KE25SC back in '07. Fs, sans the built-in LCR zobel, came out at ~1.45KHz.
Give me a minute, I'll try to post some of their measurements (fully cited, so should fall into the definition of 'fair use'. I tried earlier, but my system kept locking up...
So to sum up what you're all saying:
- It is a problem to cross this driver this low due to the LCR circuit in the driver itself (don't actually understands why) and the fact that it can increase distortion caused by breakups by forcing it to "go low"
- You more or less all agree on a steeper slope - 3rd or even 4th order for the tweeter.
- It is a problem to cross this driver this low due to the LCR circuit in the driver itself (don't actually understands why) and the fact that it can increase distortion caused by breakups by forcing it to "go low"
- You more or less all agree on a steeper slope - 3rd or even 4th order for the tweeter.
well, if your speaker really is a MTM, you have to place xo point low
and further, your woofers appear to be alu cone driver, which are mostly also crossed low, due to early and hard spiked cone breakup
as usual, things are pulling at each others legs
ever considered active ?
I would not dare to attempt doing steep crossover passively
not that I have ever tried it
and further, your woofers appear to be alu cone driver, which are mostly also crossed low, due to early and hard spiked cone breakup
as usual, things are pulling at each others legs
ever considered active ?
I would not dare to attempt doing steep crossover passively
not that I have ever tried it
oh, btw, have you ever tried to reverse the phase on tweeter ?
anyway, if you attempt to redesign the crossover, I would suggest to try it as 2.5way instead of MTM
anyway, if you attempt to redesign the crossover, I would suggest to try it as 2.5way instead of MTM
This seems like very flawed logic to me...
Distortion certainly seems like the root cause of this phenomenon to me.
Any "phase issue" will be the same independent of volume. I don't see how that can possibly explain this.
Perhaps what the builder should do is redesign the speaker to have an elevated treble or a peak around 3-5kHz. This should increase the forwardness and sparkle at all power levels.
I give up on the attachment. Probably be working again in the morning. Sorry about that.
Not exactly. The LCR zobel built into the tweeter flattens the impedance, but that doesn't mean it's a good idea to cross too close to its natural resonant frequency. Especially not with a low-order filter. Visaton have not done people many favours with that, since they haven't bothered stating what said resonant frequency actually is / was (about 1.45KHz according to K+T), nor its HD behaviour which is what you would otherwise use to guide you. According to the aforementioned magazine test, it's also more of a 3/4in model in terms of Sd than a 1in -something else that might have provided some guidance had Visaton mentioned it.
I'd look at 3rd order electrical & 2KHz as the minimum. YMMV as always.
Not exactly. The LCR zobel built into the tweeter flattens the impedance, but that doesn't mean it's a good idea to cross too close to its natural resonant frequency. Especially not with a low-order filter. Visaton have not done people many favours with that, since they haven't bothered stating what said resonant frequency actually is / was (about 1.45KHz according to K+T), nor its HD behaviour which is what you would otherwise use to guide you. According to the aforementioned magazine test, it's also more of a 3/4in model in terms of Sd than a 1in -something else that might have provided some guidance had Visaton mentioned it.
I'd look at 3rd order electrical & 2KHz as the minimum. YMMV as always.
No and Yes. The built in LCR circuit is only helping to solve any potential issues, it in and of itself will not harm anything. All it will do is make the high pass filters work more effectively at and around the tweeter resonance (in this case apparently at around 1.5kHz.)
What happens at resonance is that you get a spike in the impedance. When this occurs it reduces the effect that the high pass filter has on cutting out the lower frequencies to the tweeter. In effect the impedance spike makes the crossover let through more bass and this will increase distortion in the tweeter. With the LCR in place it flattens this spike out so that this no longer happens and the high pass works as intended. This reduces tweeter distortion. The LCR is a very good thing.
There is never really a situation where having an LCR is going to affect the loudspeakers performance in a bad way, that is providing it is designed for in the first place. There are plenty of situations where one doesn't need an LCR, but this is most certainly NOT one of them. (Crossing a tweeter at or close to its resonance is one situation where you may need one, unless it's resonance is heavily damped with viscous ferrofluid.)
Distortion is theoretically being increased because the tweeter is not capable of operating as low as you want it to. From the distortion measurements earlier however it seems quite capable for a device with such a high natural fs. The third and higher order harmonics are impressively low all things considered, down quite low in frequency. Only the second harmonic goes up, which is usually quite innocuous.
Metal coned mid/bass and MTM configurations both have their issues, both of which require a low and steep xover to minimise. What we are recommending is a 4th order ACOUSTIC crossover on the tweeter. This will probably only require a suitably configured 2nd order electrical crossover, but possibly 3rd if you need additional response shaping around the transition band of the xover, or to bring the drivers into proper phase. The tweeter will probably be able to manage with this at 2kHz, but you will be operating it at its very limits. Certainly raising this to 2.2-2.5khz might be an idea if it cannot cope, but really you'd have to try it to find out.
This will need to be met with a suitable 4th order acoustic on the mid/bass drivers at a similar frequency and you will also need to make sure that you've accounted for baffle step or the speakers will surely sound quite anaemic, unless placed in a corner or next to a wall.
BIJOU
Hi,
This is the real Bijou crossed around 2000ish and what looks like a third acoustical order on tweeter. These sound excellent according to me. However it has no waveguide as your has. If the wave guide is properly filtered, there should be less distortion than without….
I don't understand all the jibe in this thread about Bijou, mtm und so weiter. It's clearly written there is a wave guide involved here…..
Further on, high volume. What loud means to you is not necessarily loud for me or vice versa. This is a small speaker, so don't expect it to go really loud. Maybe you are pressing the poor little bastard too much and it results in second order distortion, or maybe not;o) It's just a bunch of guess work,huh?
Peter
Hi,
This is the real Bijou crossed around 2000ish and what looks like a third acoustical order on tweeter. These sound excellent according to me. However it has no waveguide as your has. If the wave guide is properly filtered, there should be less distortion than without….
I don't understand all the jibe in this thread about Bijou, mtm und so weiter. It's clearly written there is a wave guide involved here…..
Further on, high volume. What loud means to you is not necessarily loud for me or vice versa. This is a small speaker, so don't expect it to go really loud. Maybe you are pressing the poor little bastard too much and it results in second order distortion, or maybe not;o) It's just a bunch of guess work,huh?
Peter
Last edited:
Thanks for all the input guys. It is much appreciated!
The speaker is a TMM configuration and it is wall mounted.
It does not play anything below 80hz. A sub takes over from here.
I tried to google what you call the natural fs. Never heard of it and Google didn't help me out.
The T/S states that the Fs of this driver is 532Hz.
If I interpret the klirr graph correctly I should raise the XO a little bit, but not by much.
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The speaker is a TMM configuration and it is wall mounted.
It does not play anything below 80hz. A sub takes over from here.
I tried to google what you call the natural fs. Never heard of it and Google didn't help me out.
The T/S states that the Fs of this driver is 532Hz.
If I interpret the klirr graph correctly I should raise the XO a little bit, but not by much.
Sent from my iPhone using Tapatalk
again, you present problem is not distortion
phase issues is your problem
ofcourse I'm not saying tweeter distortion is of no concern
but since you like it better when playing loud, distortion is not what you struggle with right now
phase is more likely the main problem(as always)
did you try to reverse tweeter phase, like I suggested ?
TMM is good
means that it could better be redesigned as 2.5way, with higher xo point
phase issues is your problem
ofcourse I'm not saying tweeter distortion is of no concern
but since you like it better when playing loud, distortion is not what you struggle with right now
phase is more likely the main problem(as always)
did you try to reverse tweeter phase, like I suggested ?
TMM is good
means that it could better be redesigned as 2.5way, with higher xo point
As a general suggestion for future reference: if you give these sort of details from the outset, it will help considerably.
No such thing as an unnatural Fs as far as I am aware. 😉 Its just Fs -you can't see the impedance peak because it's got a built-in LCR (mostly) flattening it, so you don't have to do that yourself in the XO.
Which T/S data? There's none on Visaton's site for this tweeter -is it something you've found, or measured yourself? K+T measured Fs as 1.45KHz; I believe Hobby Hifi obtained the following data for the pair they had in:
Fs = 1.13KHz
Re = 5.9ohm
Qm = 1.6
Qe = 1.3
SPL = 89dB 1m/2.83v
Qt = 0.71
Got the Fs from boxsim...
Why would it make more sense to do a 2,5 way instead of just increasing the xo point?
I'm not expecting much bass from these and want to be able to have an overall high efficiency.
I did design the filter with phase in mind.
They are in fact in phase at xo. At least in boxsim.
Need to measure this to confirm.
Sent from my iPhone using Tapatalk
Why would it make more sense to do a 2,5 way instead of just increasing the xo point?
I'm not expecting much bass from these and want to be able to have an overall high efficiency.
I did design the filter with phase in mind.
They are in fact in phase at xo. At least in boxsim.
Need to measure this to confirm.
Sent from my iPhone using Tapatalk
Just found this:
http://www.hifisound.de/out/media/p...vM7+FMw7u4Elses7YnAW/Djo6utfxVp7W4Sdv5Q==.pdf
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http://www.hifisound.de/out/media/p...vM7+FMw7u4Elses7YnAW/Djo6utfxVp7W4Sdv5Q==.pdf
Sent from my iPhone using Tapatalk
clearly shows the early rolloff, and why you probably have a phase problem with crossing it low
phase problems are always worse at low SPL
sounds closed and muffled, and kind of 'noisy' and annoying
at high SPL it 'only' leads to 'normal' distortion
which is making up for the muffled phased sound
and what your hear as 'more crispy'
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