Patrick Sun
Senior HTF Member
- Joined
- Jun 30, 1999
- Messages
- 39,666
Now that I've gotten my SunOnes and SunTwos squared away (in my mind, at least) this past Friday and Saturday (until I get another opinion on their sound later), I figured I'd take another stab at my Center channel speaker beast I created about 4-6 months ago.
I asked one of my friends what he thought of the sound quality of it about 3 months ago, and he thought it sounded a little funny, but once you got used to it, it started to sound okay. Well, that just wasn't music to my ears, so I ordered some capacitors a few weeks ago so that I could be flexible in my CC tweaking/tune-up.
I had nothing to do Sunday, so I decided to give it a shot using the lessons I've learned since, plus the perspective I've gained by tweaking the other 2 sets of speakers. I was sort of amazed at the speed of my tweaking this time around. Then again, I didn't "document" every tweak/change in an orderly fashion, but I knew where I was, and where I wanted to be. I did make notes of each change, but didn't produce graphs upon graphs with each change
this time around.
I was bummed that my plans to replace the tweeter with the Morel MDT30s that I used in my other speakers were thwarted by the existing tweeter hole being too big! Doh! So I decided to press on with the original tweeter (from my old DIY speaker project). (after tweaking, I can't really find any reason to feel too bummed about not being able to use the Morel tweeter - I'm using an old Phillips AD11600/T8 fabric tweeter).
I used a more systematic approach this time (the previous efforts had me changing something and then taking measurements of the whole frequency response and then deciding if the change was beneficial - I
had no idea if the individual filter slope were actually working as designed). I broke the tuning down into 3 phases:
measuring the current individual drivers with their current filters in place, graphing their response, and then making
changes to get the filter slopes to cross at the desired frequencies.
So once I was happy with the woofer low pass filter, I moved on to the midrange high pass filter, got the integration of it with the woofer filter where I wanted, and then moved onto the integration of the midrange low pass filter and the tweeter high pass filter. Sounds simple, eh?
I can't believe I didn't do this the 1st time around, and I was tweaking pretty darn blindly.
I can't show the "before" situation yet (left it at home - will post it later tonight), but I can show the "after" frequency response down below. I started with the woofer response. I knew I wanted to slope off the parallelled
woofers' response around 500-700Hz (to try and get that baffle step loss minimized), and then use my midrange from around 500-3000Hz, and then let the tweeter take care of the rest.
Let just be nice and say that my initial attempt at the crossover was pretty marginal.
Once I plotted the individual response of the driver/filters, I knew why my friend said the CC sounded weird: the tweeter was padded too much, and the midrange was carrying too much of the load on the high end, and IIRC, the woofers were playing too high up the road (around 1200Hz).
After about 5 hours of tinkering with the filters, seeing if the textbook filters were doing their things (or if I noticed that the filters were "delayed" in when the slope started to kick in, I would calculate a new filter with the break frequency that was lower by 1/3 or 2/3 of an octave to get the filter to cross over as desired), I got something that started to sound "normal" to me, with slightly more tweeter output, and was able to shape the midrange output to covered the region I wanted it to cover.
I think it took 2 changes to the woofer filter, 5 changes for the midrange (for the high pass and low pass filtering), and another 3 for the tweeter filter.
What also helped was when I got my other speakers measured on the LAud setup, I was able to produce a table of RS SPL meter measurement correction values for my particular meter that gets me in the ballpark. I put these corrections values (what I needed to add or subtract from any given frequency's SPL reading - since I use 1/3 octave test tones, it's a simple matter to standardize on the corrections) in an Excel spreadsheet, and it gave me a
"better" idea of the frequency response, especially in the high frequencies after 3KHz. Believe me, it's a lot closer
than the correction values I was using before (which led me to pad my tweeters too much - usually 3dB too much).
Just keep in mind that for the low end (60-150Hz) I have this weird room mode that always accentuates the bass response, it's not as bad as it sounds/looks once the speaker is put in its place above the TV. The extended ridge in the 1KHz range is actually beneficial once the speaker is in place as well, so that's why I did not take steps to pad down the midrange. It's not all that "flat-line" pretty, but without serious measuring gear and filter design software, it gets most of the job done. So without further ado...
SunCC frequency response plot
------------------
PatCave; HT Pix; Gear; DIY Mains; DIY CC; Sunosub I + II + III; DVDs; Link Removed
I asked one of my friends what he thought of the sound quality of it about 3 months ago, and he thought it sounded a little funny, but once you got used to it, it started to sound okay. Well, that just wasn't music to my ears, so I ordered some capacitors a few weeks ago so that I could be flexible in my CC tweaking/tune-up.
I had nothing to do Sunday, so I decided to give it a shot using the lessons I've learned since, plus the perspective I've gained by tweaking the other 2 sets of speakers. I was sort of amazed at the speed of my tweaking this time around. Then again, I didn't "document" every tweak/change in an orderly fashion, but I knew where I was, and where I wanted to be. I did make notes of each change, but didn't produce graphs upon graphs with each change
this time around.
I was bummed that my plans to replace the tweeter with the Morel MDT30s that I used in my other speakers were thwarted by the existing tweeter hole being too big! Doh! So I decided to press on with the original tweeter (from my old DIY speaker project). (after tweaking, I can't really find any reason to feel too bummed about not being able to use the Morel tweeter - I'm using an old Phillips AD11600/T8 fabric tweeter).
I used a more systematic approach this time (the previous efforts had me changing something and then taking measurements of the whole frequency response and then deciding if the change was beneficial - I
had no idea if the individual filter slope were actually working as designed). I broke the tuning down into 3 phases:
measuring the current individual drivers with their current filters in place, graphing their response, and then making
changes to get the filter slopes to cross at the desired frequencies.
So once I was happy with the woofer low pass filter, I moved on to the midrange high pass filter, got the integration of it with the woofer filter where I wanted, and then moved onto the integration of the midrange low pass filter and the tweeter high pass filter. Sounds simple, eh?
I can't believe I didn't do this the 1st time around, and I was tweaking pretty darn blindly.
I can't show the "before" situation yet (left it at home - will post it later tonight), but I can show the "after" frequency response down below. I started with the woofer response. I knew I wanted to slope off the parallelled
woofers' response around 500-700Hz (to try and get that baffle step loss minimized), and then use my midrange from around 500-3000Hz, and then let the tweeter take care of the rest.
Let just be nice and say that my initial attempt at the crossover was pretty marginal.
Once I plotted the individual response of the driver/filters, I knew why my friend said the CC sounded weird: the tweeter was padded too much, and the midrange was carrying too much of the load on the high end, and IIRC, the woofers were playing too high up the road (around 1200Hz).
After about 5 hours of tinkering with the filters, seeing if the textbook filters were doing their things (or if I noticed that the filters were "delayed" in when the slope started to kick in, I would calculate a new filter with the break frequency that was lower by 1/3 or 2/3 of an octave to get the filter to cross over as desired), I got something that started to sound "normal" to me, with slightly more tweeter output, and was able to shape the midrange output to covered the region I wanted it to cover.
I think it took 2 changes to the woofer filter, 5 changes for the midrange (for the high pass and low pass filtering), and another 3 for the tweeter filter.
What also helped was when I got my other speakers measured on the LAud setup, I was able to produce a table of RS SPL meter measurement correction values for my particular meter that gets me in the ballpark. I put these corrections values (what I needed to add or subtract from any given frequency's SPL reading - since I use 1/3 octave test tones, it's a simple matter to standardize on the corrections) in an Excel spreadsheet, and it gave me a
"better" idea of the frequency response, especially in the high frequencies after 3KHz. Believe me, it's a lot closer
than the correction values I was using before (which led me to pad my tweeters too much - usually 3dB too much).
Just keep in mind that for the low end (60-150Hz) I have this weird room mode that always accentuates the bass response, it's not as bad as it sounds/looks once the speaker is put in its place above the TV. The extended ridge in the 1KHz range is actually beneficial once the speaker is in place as well, so that's why I did not take steps to pad down the midrange. It's not all that "flat-line" pretty, but without serious measuring gear and filter design software, it gets most of the job done. So without further ado...
SunCC frequency response plot
------------------
PatCave; HT Pix; Gear; DIY Mains; DIY CC; Sunosub I + II + III; DVDs; Link Removed
