Byrtt,
The 1/4 wave stubs I used previously in sims can reduce a peak but not fill a dip. I will probably have to put de'Qing holes in the vent wall to reduce it's effective length and use foam blocks in the exit vent to reduce its CSA. Not sure if it will work really. The sharpness you hear is probably combo of titanium diaphragm and the short conical internal horn in the CX that has a large discontinuity causing the rather rough response. Not the best horn for HF as I can hear. Freddi is probably right about putting a K-tube down the CX horn throat. It would be smoother than what the have there. Breaking in a Ti diaphragm may help some. I am not using any agreessive PEQ at all. Thanks for the feedback.
If I can get rid of the big dip this can really be a neat speaker. Very sensitive and loud for such a compact package.
The 1/4 wave stubs I used previously in sims can reduce a peak but not fill a dip. I will probably have to put de'Qing holes in the vent wall to reduce it's effective length and use foam blocks in the exit vent to reduce its CSA. Not sure if it will work really. The sharpness you hear is probably combo of titanium diaphragm and the short conical internal horn in the CX that has a large discontinuity causing the rather rough response. Not the best horn for HF as I can hear. Freddi is probably right about putting a K-tube down the CX horn throat. It would be smoother than what the have there. Breaking in a Ti diaphragm may help some. I am not using any agreessive PEQ at all. Thanks for the feedback.
If I can get rid of the big dip this can really be a neat speaker. Very sensitive and loud for such a compact package.
here's one of my all-time favorite cuts with Memphis Slim, T-bone Walker and Willie Dixon https://www.youtube.com/watch?v=dkEdNB0UP4w&x-yt-ts=1422579428&x-yt-cl=85114404
it also makes me think of the great old lp of Slam Stewart, Jo Jones and Milt Buckner - -here's
a tasty I IV V from that album - I had Tympani 1D in the day with this album https://www.youtube.com/watch?x-yt-cl=85114404&v=XCH_FvtBobc&x-yt-ts=1422579428
some of the best drumming uses brushing - allows a lot of subjective headroom - - I think a resonator can help a dip - if its tuned to a sizable peak preceding the dip.
it also makes me think of the great old lp of Slam Stewart, Jo Jones and Milt Buckner - -here's
a tasty I IV V from that album - I had Tympani 1D in the day with this album https://www.youtube.com/watch?x-yt-cl=85114404&v=XCH_FvtBobc&x-yt-ts=1422579428
some of the best drumming uses brushing - allows a lot of subjective headroom - - I think a resonator can help a dip - if its tuned to a sizable peak preceding the dip.
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Thanks letting us into building process.
Bandpass not my best but this reminds me the design trouble the acoustic LP functions for the tapped holes for Synergy, there you seems get LP filter cut higher up in frequency making the cones front chamber smaller and the tapped hole as near to cone center as possible. Wonder if lowering driver placement on baffle to get center more free of aperture helps get LP filter cut higher up.
Was curious seeing driver build in HF roll off and did find two different datasheets responses funny enough they share both have a build in "W".
So musical really swing, sounds as HQ recording that genre.
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You guys are right for pointing out that the driver has a natural 6dB dip, maybe that is then made worse by both the vent resonance freq and the box width frequency which all conspire to eek out a 20dB dip? I may be dealing with a trifecta here and tough to ever get rid of them all. 8cx is just not the flattest driver to start with.
if you could break up part of that mode with a partition/ reflective element - maybe too many similar dimensions
would a little "shelf" right above the driver do anything good? - that didn't seem to matter much
with a BetsyK in a tall K-coupler.
here's the 20.5" tall SK8 vs a similar height Karlsonator 6
here's a high aspect K about 28" high and 10" wide inside IIRC
would a little "shelf" right above the driver do anything good? - that didn't seem to matter much
with a BetsyK in a tall K-coupler.
here's the 20.5" tall SK8 vs a similar height Karlsonator 6
here's a high aspect K about 28" high and 10" wide inside IIRC
An externally hosted image should be here but it was not working when we last tested it.
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Reduced vent CSA and Length - worked
I went inside thru the driver cutout and cut two windows into the back wall vent to shorten it to effectively just the top piece or about 50% of the original length. I added a foam core block into the top vent to reduce the CSA by 50%. I added some foam to the internal side walls to reduce the 10in side-to-side mode. These two things seemed to get the -20dB dip to -12dB now. I then applied a PEQ peak to bring it to about 6 dB. It's interesting how adding the extra foam caused the HD to increase (I noticed this before I cut the vent holes). It just might be that there is not enough room for the driver backside to breathe that is causing this increase.
Here is the XO measurrement (2kHz 24dB BW on both) - it can be optimized some more later:
Here is the harmonic distortion, not the dip at 1.2kHz is now equivalent to the natural dip inherent in the driver:
Here is the Impulse response:
It sounds better listening to a few test tracks. I am glad this could be fixed. I will post sound clips later for you to compare.
I went inside thru the driver cutout and cut two windows into the back wall vent to shorten it to effectively just the top piece or about 50% of the original length. I added a foam core block into the top vent to reduce the CSA by 50%. I added some foam to the internal side walls to reduce the 10in side-to-side mode. These two things seemed to get the -20dB dip to -12dB now. I then applied a PEQ peak to bring it to about 6 dB. It's interesting how adding the extra foam caused the HD to increase (I noticed this before I cut the vent holes). It just might be that there is not enough room for the driver backside to breathe that is causing this increase.
Here is the XO measurrement (2kHz 24dB BW on both) - it can be optimized some more later:
Here is the harmonic distortion, not the dip at 1.2kHz is now equivalent to the natural dip inherent in the driver:
Here is the Impulse response:
It sounds better listening to a few test tracks. I am glad this could be fixed. I will post sound clips later for you to compare.
Attachments
Sound clips in Beta 8cx XKi with modified vent
The first two are recorded with the speaker on a stand and away from a back wall, the remaining are with the speaker on the floor with back a few inches away from wall.
Edit: last one is actually on a stand and not floor - good to check revealing abilities of the CD and crispness of percussion
The first two are recorded with the speaker on a stand and away from a back wall, the remaining are with the speaker on the floor with back a few inches away from wall.
Edit: last one is actually on a stand and not floor - good to check revealing abilities of the CD and crispness of percussion
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Not yet but is on my to do list. I have the perfect track: Dave Brubeck's Sermon on the Mount. Then Karl Ditter Von Dittersdorf's Concerto for Double Bass in E-flat Major.
Yes, I am pleasantly surprised by how good the D280Ti sounds. PRV makes good stuff, I like their 5MR450NDY as a fullrange too.
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here's a performance to try https://www.youtube.com/watch?v=VMoEo9tbNhk
a Karlson K15 with Altec 604 was much better than my Klipschorns on the Gary Karr "Spirit of Koussevitzky" cd
a Karlson K15 with Altec 604 was much better than my Klipschorns on the Gary Karr "Spirit of Koussevitzky" cd
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Akabak script for 6th order series band pass
As promised, here is the Akabak script for simulating the XKi (prior to K aperture swap for second vent). It is 9 lines of code - a testament to how efficient and compact Akabak is.
Here is how to use it:
1. Download Akabak (free), find a pre 64-bit Win machine, an old XP box or laptop is good.
2. Install Akabak
3. Copy the script and paste into a "new script" window in Akabak
4. Click the "SPL" button to get freq response (set vertical axis to 60dB to 110dB, set drive voltage to 2.83v), click "Xm" button to calculate xmax, click "Zin" button to calculate impedance.
5. To modify for your design, add new driver TS parameters (line 2 and change reference in line 4), lines 4, 5, 6, 7 set the chamber volumes, and vent dimensions. You can use English or Metric (12.0in or 3.67cm for example), set high pass 24dB/oct filter freq on line 3.
6. Rerun by clicking SPL button. If you made mistake, it will tell you where. If you want to turn something off, precede the line with OFF. A vertical bar | signifies everything after is a comment.
You can have variables that you set at the begining with the following construct:
Def_Const
{
x=100;
y=35.0;
}
To use variables later put braces around them like
Len={x}
dD={y}
Good luck!
As promised, here is the Akabak script for simulating the XKi (prior to K aperture swap for second vent). It is 9 lines of code - a testament to how efficient and compact Akabak is.
Here is how to use it:
1. Download Akabak (free), find a pre 64-bit Win machine, an old XP box or laptop is good.
2. Install Akabak
3. Copy the script and paste into a "new script" window in Akabak
4. Click the "SPL" button to get freq response (set vertical axis to 60dB to 110dB, set drive voltage to 2.83v), click "Xm" button to calculate xmax, click "Zin" button to calculate impedance.
5. To modify for your design, add new driver TS parameters (line 2 and change reference in line 4), lines 4, 5, 6, 7 set the chamber volumes, and vent dimensions. You can use English or Metric (12.0in or 3.67cm for example), set high pass 24dB/oct filter freq on line 3.
6. Rerun by clicking SPL button. If you made mistake, it will tell you where. If you want to turn something off, precede the line with OFF. A vertical bar | signifies everything after is a comment.
You can have variables that you set at the begining with the following construct:
Def_Const
{
x=100;
y=35.0;
}
To use variables later put braces around them like
Len={x}
dD={y}
Good luck!
xrk et al,
Great work on the Xki project. I am thinking of a design for a K type project and was wondering if any of the recommended drivers can be mounted on the rear of the driver baffle and whether the resulting thickness of the driver baffle in front of the speaker would cause any problems.
Thanks for the help,
Myles
Great work on the Xki project. I am thinking of a design for a K type project and was wondering if any of the recommended drivers can be mounted on the rear of the driver baffle and whether the resulting thickness of the driver baffle in front of the speaker would cause any problems.
Thanks for the help,
Myles
That is fine to rear mount drivers. Be aware that HF's from a full range driver may have different frequency response if rear mounted in too deep of a baffle. You will need removable back panel to access the driver.
Thanks,
The baffle will be wood, so I am thinking maybe 1/4" or 3/8" thick. Possible chamfer on the front side, to open up a bit, but not a full wave guide.
I will have to decide whether I want front access or back access. I am leaning toward back access, as it looks better cosmetically.
Will keep track of other posts and see what others think
Myles
The baffle will be wood, so I am thinking maybe 1/4" or 3/8" thick. Possible chamfer on the front side, to open up a bit, but not a full wave guide.
I will have to decide whether I want front access or back access. I am leaning toward back access, as it looks better cosmetically.
Will keep track of other posts and see what others think
Myles
some slap upright bass - the second example with Dubouchet's interpretation of Willie Dixon's "Bassology" has a bit too much sustain or reverb - but its good technique wise - maybe it sounds better on speakers than on headphones - how large of a speaker size does it take to convince there's a real upright *** in the room? I don't remember a Kay upright sounding really "loud"
https://www.youtube.com/watch?v=HxTVZ03q-UA
https://www.youtube.com/watch?v=sdWey_9H17E
https://www.youtube.com/watch?v=eSCgb4SE7uw
https://www.youtube.com/watch?v=Z0B5rEqfC_Q
https://www.youtube.com/watch?v=HxTVZ03q-UA
https://www.youtube.com/watch?v=sdWey_9H17E
https://www.youtube.com/watch?v=eSCgb4SE7uw
https://www.youtube.com/watch?v=Z0B5rEqfC_Q
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I never listened to slap bass before. Kind of cool.
http://youtu.be/g_LSbxKEYkQ
I will let you know how the XKi Beta 8cx does with this.
http://youtu.be/g_LSbxKEYkQ
I will let you know how the XKi Beta 8cx does with this.
More Sound Clips with XKi Beta 8cx
Ok Freddi, here are some more sound clips that you have requested so that you get a better idea of what this little box can do. First up is some slap stand-up double bass (the Fick track, I think). My opinion is that the XKi does a super job of making me think that Fick was playing there in the room with me. The dynamics is great and I could feel the slap pulses on my body and floor. Then we have some good old stuff from Porter Wagoner that sounds like it was just made for a Karlson or an XKi (I have never heard of him before, and his music, although not something I normally listen to, is very compelling and visceral - something about it...), and then some cello from Brubeck. For the Brubeck, I have also included a clip from my reference speaker system (response is +/-3dB from 30Hz to 20kHz, clean impulse, 100dB sensitivity at 2.83v and 1m with less than 0.5% THD from 50Hz to 20kHz at 100dB, phase +/- 23 deg from 100Hz to 20kHz) so you can compare how the XKi stands up against the "best" that I have. Finally, I have included what I could of a flac lossless file of the slap bass (very short duration) so you can see if there is any difference compared to the 192kbit mp3 file.
Enjoy...
Ok Freddi, here are some more sound clips that you have requested so that you get a better idea of what this little box can do. First up is some slap stand-up double bass (the Fick track, I think). My opinion is that the XKi does a super job of making me think that Fick was playing there in the room with me. The dynamics is great and I could feel the slap pulses on my body and floor. Then we have some good old stuff from Porter Wagoner that sounds like it was just made for a Karlson or an XKi (I have never heard of him before, and his music, although not something I normally listen to, is very compelling and visceral - something about it...), and then some cello from Brubeck. For the Brubeck, I have also included a clip from my reference speaker system (response is +/-3dB from 30Hz to 20kHz, clean impulse, 100dB sensitivity at 2.83v and 1m with less than 0.5% THD from 50Hz to 20kHz at 100dB, phase +/- 23 deg from 100Hz to 20kHz) so you can compare how the XKi stands up against the "best" that I have. Finally, I have included what I could of a flac lossless file of the slap bass (very short duration) so you can see if there is any difference compared to the 192kbit mp3 file.
Enjoy...