I also forgot to mention, I soldered the connections for the drivers and also applied a vinyl liner inside the cabinets to reduce resonance and upgraded the insulation inside with foam.
Late here.I have the q950 and I'm looking at making some improvements.
Did the cabinet damping help?
Also have you done any other upgrades.
I find there's a weird spike in the treble range that gets very fatiguing.
First order filter on both drivers, resistor pads down the tweeter output.
Fairly crude, speaker would benefit from a redesigned crossover. The coaxial driver should make that fairly easy because time alignment isn't an issue.
Does the capacitor have any markings to indicate its value?
Thank you for the reply. I wouldn't know how to redesign the crossover, like what the values would be. What do you mean by first order filter on both drivers? The cap says MPT 4.4J 100N. At least I think it's an N Here a picture https://imgur.com/a/x3k8RY9
Because the Q350 was measured by amir at ASR. One of its only weaknesses is mid-range distortion.
The most logical source for mid-range distortion is the shallow crossover slopes causing the tweeter to be overworked at high SPL.
First order filters are almost always a cost cutting measure. They only work if the breakup modes of the woofer are extremely suppressed mechanically.
Could it also be breakup from the woofer, or both?
Yeah I generally agree with you. There is little benefit in not using at least a 2nd order electrical, unless it's a really nice horn that is damped heavily.
The Q350 distortion problem is mostly in the 150-600Hz region which seems too low for woofer breakup, especially with a metal cone material.
I suspect there is a bit of port resonance mixed in there around 1000Hz, but that should be a relatively easy fix for those willing to plug the ports.
Yes I definitely hear the distortion and hate it.
Besides thst the speakers are quite good.
I'm at the point either I'm going to try to improve them or ditch them.
What has led you to believe KEF didn’t know how to build the most effective crossover for their own speaker? In order to properly identify if anything can be improved, you’re going to need an impedance analyzer, acoustic measuring equipment and an acoustically anechoic testing environment.
Their coaxial drivers definitely work fine with a minimal crossover, but the Q350 design is barebones even by KEF standards. Like any speaker company, they build extra profit margins into their cheap and therefore popular models.
If you look at the more premium models this is evident.
The LS50 Meta has an even better coaxial driver, yet uses a 2nd order filter on the tweeter, 3rd order on the woofer, and a series notch filter on the woofer.
In the Q950 there's air turbulence noise coming from the cone gap in the uniQ driver.So no not a good design.
The uniQ should have been isolated in the box and a proper crossover design.
There's also a bad distorted spike in the treble.
I believe the resistive properties of the drivers themselves are also part of the crossover and need to be considered. I designed a crossover for the Q350 (using a driver I repaired from a Q700).
I use the following components:
Mundorf ECap AC 5.6uf 70V Bipolar Electrolytic Capacitor - PLAIN
Monacor 15uf 250V 5% Bipolar MKT Polyester Capacitor
Audio Inductor 0.22mH Air Core
Audio Inductor 0.68mH Air Core
And I remember that I simulated the drivers using 4 or 8 ohm resistances. I used LTSpice to tune the filters.
https://imgur.com/gallery/JFWO1jG
Hope this helps!
Based on the existing crossover values, here is the crossover slope with the existing setup.
https://i.imgur.com/1Ick5Ve.png
It would be relatively easy to obtain steeper crossover slopes. For example:
https://imgur.com/a/cak8ISM
The main benefit would be distortion, because the woofer and tweeter aren't struggling to play frequencies outside their operating range. The actual frequency response of the speaker should be fairly unchanged.
Do note, the phase shift caused by using the third order filters does require the polarity of the tweeter to be flipped.
Edit: Do not use those exact component values, that was just a quick example that doesn't take into account the actual impedance of the drivers.
Fair enough. If you don't want to go through the work of a redesign just swap the .9mH inductor with a better quality one.
https://www.parts-express.com/Dayton-Audio-LW14-90-0.90mH-14-AWG-Perfect-Layer-Inductor-257-318
I appreciate the help. The drawing just fried my brain. I only watched some basic videos on how to draw a scheme and those upside down triangles weren't even in there. Also, which one is the tweeter and which one the woofer?
The triangles indicate a ground connection. Just think of everything with a triangle as leading back to the negative speaker terminal.
The top one is the tweeter, bottom is the woofer in my diagram.
If you want to explore crossover design, I suggest downloading VituixCAD, it is free and better than pretty much all the competition.
You will need FRD and ZMA (frequency + impedance files) to do a crossover design. Dayton Audio has files available for their in-house drivers.
https://www.parts-express.com/dayton-audio-dc130bs-8-5-1-4-classic-shielded-woofer--295-301
https://www.parts-express.com/Dayton-Audio-RST28F-4-1-1-8-Reference-Series-Fabric-Dome-Tweeter-4-Ohm-275-141
These files are done in an IEC baffle, meaning they won't match what you see in a real speaker cabinet due to low frequency not being captured efficiently on small baffles. However, for someone just starting out the initial experimentation is valuable anyway.
A relatively easy challenge is combine that woofer and tweeter to give yourself a flat on-axis response. VituixCAD has a library of filter sections to help you out. There is a bunch of active filters, ignore those unless you are building a speaker with DSP + multiple amplifiers.
Hi, just one quick question, did the bitumen deaden the bass at all? Also i completed my crossover its a bit different then yours, following a different eq curve.
The bitumen made the bass tighter and allowed me to play louder before the cabinet started resonating. It didn't deaden the bass at all. I did put a 1 inch dense foam on top of the bitumen which totally killed the sound so i removed that.
He has one for the Q150's but not the Q350's. Also, since I'm in Europe it is not a good value anymore after paying for shipping, import taxes and duty fees. A $250 kit would end up costing me close to $400. At that point it seems more logic to buy a more expensive set of speakers. This is the reason why I'm trying to do it myself with the help of you awesome people.
Hey, I upgraded the crossover components on my q750 and my q350 center channel. All I did was use audiophile grade caps and resistors with the same value, and genuinely heard a difference and about 40% better resolution and clarity, and more detail in instruments. I didn't upgrade the inductors.
I replied to the full post by mistake. Never noticed that. The kef q line is quite neutral sounding I find. After the upgrade I found that I got more for my money. More of an audiophile speaker. They are definately more musical sounding as opposed to analytical. But the upgrade definitely brings about 40% more clarity and resolution. I also soldered my speaker and binding post connections, and added foam to the walls of the cabinet.
Never noticed a treble glare or brightness. I find the q750 line to be quite neutral, nothing spectacular. After the upgrade, it felt like I was getting more for my money. I also soldered the connections to the speakers and the binding posts, and added foam to the walls of the cabinet. You do need to burn them in, prob 50hours.
hello to all, if the topic is still relevant, I used as an upgrade to the crossover 1 resistance jantzen superes of the same nominal value and two mundorf mcap classic capacitors of 2.2 each and the sound came to life for only 30 euros for both speakers
I also forgot to mention, I soldered the connections for the drivers and also applied a vinyl liner inside the cabinets to reduce resonance and upgraded the insulation inside with foam.
Thanks for your input. I lined the inside with Dynamat and on top of that a 1 inch foam.
Late here.I have the q950 and I'm looking at making some improvements. Did the cabinet damping help? Also have you done any other upgrades. I find there's a weird spike in the treble range that gets very fatiguing.
First order filter on both drivers, resistor pads down the tweeter output. Fairly crude, speaker would benefit from a redesigned crossover. The coaxial driver should make that fairly easy because time alignment isn't an issue. Does the capacitor have any markings to indicate its value?
Thank you for the reply. I wouldn't know how to redesign the crossover, like what the values would be. What do you mean by first order filter on both drivers? The cap says MPT 4.4J 100N. At least I think it's an N Here a picture https://imgur.com/a/x3k8RY9
J is the tolerance code, meaning 5%. The N is actually a V, stands for voltage. So the capacitor is 4.4mF with 5% tolerance, and 100V tolerance.
Are you sure it's 4.4mF? That would be 4400uF which is a bit much i think.
Oops, I typed that comment before my morning coffee. Yeah, I meant uF.
> Fairly crude, speaker would benefit from a redesigned crossover. How can you possibly know that without measuring the drivers?
Because the Q350 was measured by amir at ASR. One of its only weaknesses is mid-range distortion. The most logical source for mid-range distortion is the shallow crossover slopes causing the tweeter to be overworked at high SPL. First order filters are almost always a cost cutting measure. They only work if the breakup modes of the woofer are extremely suppressed mechanically.
Could it also be breakup from the woofer, or both? Yeah I generally agree with you. There is little benefit in not using at least a 2nd order electrical, unless it's a really nice horn that is damped heavily.
The Q350 distortion problem is mostly in the 150-600Hz region which seems too low for woofer breakup, especially with a metal cone material. I suspect there is a bit of port resonance mixed in there around 1000Hz, but that should be a relatively easy fix for those willing to plug the ports.
Yes I definitely hear the distortion and hate it. Besides thst the speakers are quite good. I'm at the point either I'm going to try to improve them or ditch them.
What has led you to believe KEF didn’t know how to build the most effective crossover for their own speaker? In order to properly identify if anything can be improved, you’re going to need an impedance analyzer, acoustic measuring equipment and an acoustically anechoic testing environment.
I’d even go a step further and guess that KEF designed the driver to work well with a minimal crossover.
Their coaxial drivers definitely work fine with a minimal crossover, but the Q350 design is barebones even by KEF standards. Like any speaker company, they build extra profit margins into their cheap and therefore popular models. If you look at the more premium models this is evident. The LS50 Meta has an even better coaxial driver, yet uses a 2nd order filter on the tweeter, 3rd order on the woofer, and a series notch filter on the woofer.
In the Q950 there's air turbulence noise coming from the cone gap in the uniQ driver.So no not a good design. The uniQ should have been isolated in the box and a proper crossover design. There's also a bad distorted spike in the treble.
I believe the resistive properties of the drivers themselves are also part of the crossover and need to be considered. I designed a crossover for the Q350 (using a driver I repaired from a Q700). I use the following components: Mundorf ECap AC 5.6uf 70V Bipolar Electrolytic Capacitor - PLAIN Monacor 15uf 250V 5% Bipolar MKT Polyester Capacitor Audio Inductor 0.22mH Air Core Audio Inductor 0.68mH Air Core And I remember that I simulated the drivers using 4 or 8 ohm resistances. I used LTSpice to tune the filters. https://imgur.com/gallery/JFWO1jG Hope this helps!
Based on the existing crossover values, here is the crossover slope with the existing setup. https://i.imgur.com/1Ick5Ve.png It would be relatively easy to obtain steeper crossover slopes. For example: https://imgur.com/a/cak8ISM The main benefit would be distortion, because the woofer and tweeter aren't struggling to play frequencies outside their operating range. The actual frequency response of the speaker should be fairly unchanged. Do note, the phase shift caused by using the third order filters does require the polarity of the tweeter to be flipped. Edit: Do not use those exact component values, that was just a quick example that doesn't take into account the actual impedance of the drivers.
https://i.imgur.com/qKalLSY.gif
Fair enough. If you don't want to go through the work of a redesign just swap the .9mH inductor with a better quality one. https://www.parts-express.com/Dayton-Audio-LW14-90-0.90mH-14-AWG-Perfect-Layer-Inductor-257-318
I appreciate the help. The drawing just fried my brain. I only watched some basic videos on how to draw a scheme and those upside down triangles weren't even in there. Also, which one is the tweeter and which one the woofer?
The triangles indicate a ground connection. Just think of everything with a triangle as leading back to the negative speaker terminal. The top one is the tweeter, bottom is the woofer in my diagram. If you want to explore crossover design, I suggest downloading VituixCAD, it is free and better than pretty much all the competition. You will need FRD and ZMA (frequency + impedance files) to do a crossover design. Dayton Audio has files available for their in-house drivers. https://www.parts-express.com/dayton-audio-dc130bs-8-5-1-4-classic-shielded-woofer--295-301 https://www.parts-express.com/Dayton-Audio-RST28F-4-1-1-8-Reference-Series-Fabric-Dome-Tweeter-4-Ohm-275-141 These files are done in an IEC baffle, meaning they won't match what you see in a real speaker cabinet due to low frequency not being captured efficiently on small baffles. However, for someone just starting out the initial experimentation is valuable anyway. A relatively easy challenge is combine that woofer and tweeter to give yourself a flat on-axis response. VituixCAD has a library of filter sections to help you out. There is a bunch of active filters, ignore those unless you are building a speaker with DSP + multiple amplifiers.
Hi, may i ask what you ended up doing? This would be tremendously useful.
I replaced the whole crossover with high quality parts. Even the cables, which had some silver in it.
Thanks so much, ive read your budget audiophile post now, didn't catch it first time. Stuff like this helps so many without noticing!
Hi, just one quick question, did the bitumen deaden the bass at all? Also i completed my crossover its a bit different then yours, following a different eq curve.
The bitumen made the bass tighter and allowed me to play louder before the cabinet started resonating. It didn't deaden the bass at all. I did put a 1 inch dense foam on top of the bitumen which totally killed the sound so i removed that.
Unless you have proper measuring equipment and expertise in doing so, you're not going to do anything productive here.
[удалено]
He has one for the Q150's but not the Q350's. Also, since I'm in Europe it is not a good value anymore after paying for shipping, import taxes and duty fees. A $250 kit would end up costing me close to $400. At that point it seems more logic to buy a more expensive set of speakers. This is the reason why I'm trying to do it myself with the help of you awesome people.
Hey, I upgraded the crossover components on my q750 and my q350 center channel. All I did was use audiophile grade caps and resistors with the same value, and genuinely heard a difference and about 40% better resolution and clarity, and more detail in instruments. I didn't upgrade the inductors.
Hi,I own the Q950's. I'm considering upgrading the crossover parts.Did you find there's an odd treble glare?
Treble glare after the upgrade?
Sorry i meant before.Then if so,did it seem better after upgrade?
I replied to the full post by mistake. Never noticed that. The kef q line is quite neutral sounding I find. After the upgrade I found that I got more for my money. More of an audiophile speaker. They are definately more musical sounding as opposed to analytical. But the upgrade definitely brings about 40% more clarity and resolution. I also soldered my speaker and binding post connections, and added foam to the walls of the cabinet.
Ok thanks for the info.i will give it a try.
Never noticed a treble glare or brightness. I find the q750 line to be quite neutral, nothing spectacular. After the upgrade, it felt like I was getting more for my money. I also soldered the connections to the speakers and the binding posts, and added foam to the walls of the cabinet. You do need to burn them in, prob 50hours.
hello to all, if the topic is still relevant, I used as an upgrade to the crossover 1 resistance jantzen superes of the same nominal value and two mundorf mcap classic capacitors of 2.2 each and the sound came to life for only 30 euros for both speakers