Hi Shin,
Awesome speakers! I've been following this thread for quite a while now. As has been said here so many times already, your work is very inspiring. I noticed that your using the Emu 1820M as your audio interface now. I'm using Emu's 1212M right now and I've been thinking about picking up an Audiodock or a whole 1820M off of e-bay to get the 8 channels out. Your positive experience with using it for a crossover duties is pushing me in that direction.
I'd also use it for measurement and there's something I'm wondering about. Emu only give specs on their soundcards for 20-20kHz on the analog outs even though that dac and the card can operate at 192kHz. I'd seen some tests with the Soundblaster X-fi which I believe uses the same dacs and is also a Creative Labs family product. Even though that card could also run at higher sampling rates, it looked like it had a brick wall lowpass filter slightly above 20kHz, at least on the line in. For testing, it would be nice to get some of those higher frequencies to preserve tweeter phase information lower down. From you loudspeader testing, does it look like the 1820M is taking in anything above 20k?
thanks!
Dan
Awesome speakers! I've been following this thread for quite a while now. As has been said here so many times already, your work is very inspiring. I noticed that your using the Emu 1820M as your audio interface now. I'm using Emu's 1212M right now and I've been thinking about picking up an Audiodock or a whole 1820M off of e-bay to get the 8 channels out. Your positive experience with using it for a crossover duties is pushing me in that direction.
I'd also use it for measurement and there's something I'm wondering about. Emu only give specs on their soundcards for 20-20kHz on the analog outs even though that dac and the card can operate at 192kHz. I'd seen some tests with the Soundblaster X-fi which I believe uses the same dacs and is also a Creative Labs family product. Even though that card could also run at higher sampling rates, it looked like it had a brick wall lowpass filter slightly above 20kHz, at least on the line in. For testing, it would be nice to get some of those higher frequencies to preserve tweeter phase information lower down. From you loudspeader testing, does it look like the 1820M is taking in anything above 20k?
thanks!
Dan
Here's a silly idea - why not record the speakers playing some music and post the recording online for people to listen to on headphones? I am completely aware of why this is silly but I think some SORT of idea of how a speaker sounded could be realised from this. I think more people should do this! IE "Help me cure my midrange honk! Listen to this recording"
This isn't specifically aimed at the OP but speaker builders in general..
This isn't specifically aimed at the OP but speaker builders in general..
Hi Motion,
Programs like SoundEasy need to know the high and low end rolloffs of your drivers to accurate determine the minimum phase response. You need this to perform an accurate crossover simulation, at least the way SoundEasy does things. Check out Dave's speaker pages for a better description of this: Dave's Speaker Pages
Click on Driver Model Accuracy and its Impact on Phase for a full description of this. John Kreskovsky also has an excellent explanation of this somewhere on his site.
I would also imagine it would be important when performing the driver corrections as Ant has done with his Acourate generated filters. For most tweeters I believe the high end rolloff will occur above 20kHz. At least with SoundEasy, if you only have data up to 20k or so, you'll have to guess at what frequency the tweeter will start dropping off and you'll also have to guess what slope it will roll off at. If you get it wrong, the calculated minimum phase will not be quite right, even all the way down at a crossover frequency of 2.5 kHz. How much it could be off in the case of my speakers I'm not sure. I'm still measuring with an old Soundblaster Live which cuts out at 22kHz. This doesn't let me see any of my tweeter's rolloff, it's a straight line to 22 kHz on-axis. I'd assume this would be much easier to get right if you have a mic and soundcard that can measure high enough to show some of the tweeter's upper end rolloff.
Anyway, since Emu only give specs up to 20kHz it makes me wonder if they're letting anything through above that even when the card is set to higher sample rates.
Dan
Programs like SoundEasy need to know the high and low end rolloffs of your drivers to accurate determine the minimum phase response. You need this to perform an accurate crossover simulation, at least the way SoundEasy does things. Check out Dave's speaker pages for a better description of this: Dave's Speaker Pages
Click on Driver Model Accuracy and its Impact on Phase for a full description of this. John Kreskovsky also has an excellent explanation of this somewhere on his site.
I would also imagine it would be important when performing the driver corrections as Ant has done with his Acourate generated filters. For most tweeters I believe the high end rolloff will occur above 20kHz. At least with SoundEasy, if you only have data up to 20k or so, you'll have to guess at what frequency the tweeter will start dropping off and you'll also have to guess what slope it will roll off at. If you get it wrong, the calculated minimum phase will not be quite right, even all the way down at a crossover frequency of 2.5 kHz. How much it could be off in the case of my speakers I'm not sure. I'm still measuring with an old Soundblaster Live which cuts out at 22kHz. This doesn't let me see any of my tweeter's rolloff, it's a straight line to 22 kHz on-axis. I'd assume this would be much easier to get right if you have a mic and soundcard that can measure high enough to show some of the tweeter's upper end rolloff.
Anyway, since Emu only give specs up to 20kHz it makes me wonder if they're letting anything through above that even when the card is set to higher sample rates.
Dan
Dan, EMU isn't an X-FI or Audigy. Different designs intended for different markets.
Read some reviews and look at the Rightmark results.
Reason why older creative products brickwall at 22Khz is because of the 48Khz internal sampling conversion that was imposed on anything and everything regardless of what sampling frequency you choose.
Not a problem with EMU cards, however you will need a mic that measures past 20Khz. Behringer ECM 8000 is only reliable to about 18Khz. I do not correct frequencies above 16Khz for this reason and rely on the natural behaviour on the driver.
Read some reviews and look at the Rightmark results.
Reason why older creative products brickwall at 22Khz is because of the 48Khz internal sampling conversion that was imposed on anything and everything regardless of what sampling frequency you choose.
Not a problem with EMU cards, however you will need a mic that measures past 20Khz. Behringer ECM 8000 is only reliable to about 18Khz. I do not correct frequencies above 16Khz for this reason and rely on the natural behaviour on the driver.
ackcheng said:
That's good news then.
Try playing with the stuffing on the mid driver. Doing so makes subtle differences to the subjective speed of the sound although looking at the CSD's it hardly makes much difference. I have manage to tweak out some minor dips in the driver response when measured near field so maybe thats it.
Here's how I have it now:
An externally hosted image should be here but it was not working when we last tested it.
Wool up front directly behind the driver on all walls, then a gap with just 10mm foam on the walls and right to the rear there a dense fill of wool with a large chunk of foam behind it.
Also bought a few huge bass traps to try and do something with the bass issues I'm having. Just finished putting those up so will have a measure and see what sort of difference its made.
Huge difference with the 6 bass traps and side wall panels:
Before:
After:
I took the measurement at 7dB higher than the 'before' measurement time so as to clear all the background noise from measurement.
I needed something busy in the bass to test the effectivness of these out on so I'm listening to some Goa trance which is beat heavy. The difference is readily apparent and not subtle at all. Digital room correction gets you so far but there's no substitute for bass traps. The combination of the two has resulted in clean and clear bass that fully integrated with the music. The pitch definition is more like headphones now but with much greater scale.
The bass traps are these:
http://cgi.ebay.co.uk/Acoustic-Trea...oryZ3278QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
In case I hadn't mentioned it before, they're huge! The size is around 2ft x 2ft x 3ft in a wedge shape. They're placed in the wall to ceiling corners and I have two and half at the front across the whole width of the room, 2 at the rear and the remaining one and half on the left wall. They're ugly as hell in grey but I plan to cover these in a similar colour fabric to that on the walls.
As well as this I've put up two large 8ft x 2ft panels built out of 15cm thick acoustic foam I had left over from my previous room treatments efforts, these panels have been stuck on a 6mm ply sheet and then finished off with a covering of material to make it look less ugly. Each panel has been placed at the first reflection point on the sidewalls next to the speakers. Doing this has calmed the slightly busy nature of the treble and upper mids. Imaging and soundstage have become larger and more well defined although they were good to start with.
Before:
An externally hosted image should be here but it was not working when we last tested it.
After:
An externally hosted image should be here but it was not working when we last tested it.
I took the measurement at 7dB higher than the 'before' measurement time so as to clear all the background noise from measurement.
I needed something busy in the bass to test the effectivness of these out on so I'm listening to some Goa trance which is beat heavy. The difference is readily apparent and not subtle at all. Digital room correction gets you so far but there's no substitute for bass traps. The combination of the two has resulted in clean and clear bass that fully integrated with the music. The pitch definition is more like headphones now but with much greater scale.
The bass traps are these:
http://cgi.ebay.co.uk/Acoustic-Trea...oryZ3278QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
In case I hadn't mentioned it before, they're huge! The size is around 2ft x 2ft x 3ft in a wedge shape. They're placed in the wall to ceiling corners and I have two and half at the front across the whole width of the room, 2 at the rear and the remaining one and half on the left wall. They're ugly as hell in grey but I plan to cover these in a similar colour fabric to that on the walls.
As well as this I've put up two large 8ft x 2ft panels built out of 15cm thick acoustic foam I had left over from my previous room treatments efforts, these panels have been stuck on a 6mm ply sheet and then finished off with a covering of material to make it look less ugly. Each panel has been placed at the first reflection point on the sidewalls next to the speakers. Doing this has calmed the slightly busy nature of the treble and upper mids. Imaging and soundstage have become larger and more well defined although they were good to start with.
Fantastic measurements, finally real life graphical representation of bass traps at work. I will now have to buy some for me.
Your project is doing great. I'm also using Creative's card for testing crossover points and slopes, although much cheaper and older SB Live! 5.1. With Kx drivers it does pretty much the same work as emu, but i'm considering buying some of emu models so i can use them as primary music source. (or some external dac)
Will you use Emu card for digital crossover,eq,delay... or will it all be inside your digitaly controlled preamp? (some dsp?)
Mx
Your project is doing great. I'm also using Creative's card for testing crossover points and slopes, although much cheaper and older SB Live! 5.1. With Kx drivers it does pretty much the same work as emu, but i'm considering buying some of emu models so i can use them as primary music source. (or some external dac)
Will you use Emu card for digital crossover,eq,delay... or will it all be inside your digitaly controlled preamp? (some dsp?)
Mx
Gee Shin, the CSD graphs really show the effectiveness of the traps.
Most try and use waterfalls to see a before and after difference, which you of course can to a degree, but to my eyes the difference is much more easily seen with the csd presented in that format.
Pity I don't know how to do it, plenty of time to learn yet as my homemade bass traps are still a while away.
Will wait for your tutorial ha ha ha.
Most try and use waterfalls to see a before and after difference, which you of course can to a degree, but to my eyes the difference is much more easily seen with the csd presented in that format.
Pity I don't know how to do it, plenty of time to learn yet as my homemade bass traps are still a while away.
Will wait for your tutorial ha ha ha.
Just want to report back my experience of using various crossover setting for my speaker
The first is my original setting with 150/350/2000 96dB: This gives a very thin sound for the mid range with loss in dynamics but the sound is "faster" with a more clear mid high. the high notes for a female soprano seems more clear
The second is 60/200/3000 24dB: In many ways the mid range is better with better dynamics and thicker sound. There are more substance in the mid region. However, this setting is "slower" and the high note is not as clear. May be my AT 18cm has not fully breakin in this region?
The third is 60/200/3000 18dB: This is even slower
Next I will try 60/200/2500 for the best comprimise. I will also try to use different slope for the high and low pass filter to see if there is any difference.
The first is my original setting with 150/350/2000 96dB: This gives a very thin sound for the mid range with loss in dynamics but the sound is "faster" with a more clear mid high. the high notes for a female soprano seems more clear
The second is 60/200/3000 24dB: In many ways the mid range is better with better dynamics and thicker sound. There are more substance in the mid region. However, this setting is "slower" and the high note is not as clear. May be my AT 18cm has not fully breakin in this region?
The third is 60/200/3000 18dB: This is even slower
Next I will try 60/200/2500 for the best comprimise. I will also try to use different slope for the high and low pass filter to see if there is any difference.
ackcheng said:
Hi Arthur
Its like deja vu when I read back your posts. Obviously our systems are similar in traits given the parallels between our drivers selections.
My last post on the previous page was talking about the midrange speed and clarity. I have really got the last ounce of mid clarity and speed out of the design using lots of experimentation with stuffing densities and types.
You'll find this makes a most apparent difference to the overall clarity and hence perceived speed from the mids. With minimal treatment it sounds dynamic and forward but edgey and less focused. It has more a raw untamed quality that works well with some music but complex passages sound slightly congested and busy.
With a middle ground setting you get a calmer sound but more restrained sound. I initially liked this setup but its missing something, as if the speaker is restrained at the top end but still loose and a little out of control down lower. I guess you could say unbalanced.
And a heavy treatment is what I use now. The clarity is great and the whole range is smooth, calm but still lucid and alive. I have a nice balance of dynamic, speed and definition.
Its a shame I don't have a shot of the stuffing setup but here are some old shots:
2mm lead lining on walls for controlling box related resonances:
On top of the lead goes 2mm bitumen sheet and stuck onto that is 10mm thick acoustic foam:
Also placed in the mid chamber are these irregular shaped acoustic foam treatments. But not shown in any of these shots is the addition of wool placed directly behing the mid driver covering the walls and finally right to the rear of the chamber is a dense fill of wool which sits in front of the thick wedge of acoustic foam.
Things like this can easily be added or taken away through the driver opening for experimentation. Try treating one speaker and leaving the other as is so you can directly compare the differences.
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