That amp can handle 1ohm but 2ohm should work well and give way more power capability than running 8ohm. Thanks for clarifying that the Vas Qts and fs stay the same. What about Bl though?
Download and install REW. Connect mic and run program. Go into setup to configure mic to make sure it works. If you have cal file install file. Click measure button. Need to connect amp to headphone out of pc or laptop soundcard. Set the gain on soubd card and set amp level so mic doesn't clip.
This is what I get. I don't know if it is correct. I measure it at 2.83v with the mic close to the box
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Nice work!
Your measurement is tracking the prediction as it is down -5dB from 50Hz at 35Hz. You may have some room modes going on around 80-100hz that is causing those dips. The sensitivity I can't tell unless you measure how far away the mic is and wire it 2ohms (series within ea driver and parallel between drivers). 100dB with. 2.83v at 8ohm isn't bad though. Can you post the harmonic distortion tab? Pick all harmonics up to 5th.
Here is prediction without extension duct:
Your measurement is tracking the prediction as it is down -5dB from 50Hz at 35Hz. You may have some room modes going on around 80-100hz that is causing those dips. The sensitivity I can't tell unless you measure how far away the mic is and wire it 2ohms (series within ea driver and parallel between drivers). 100dB with. 2.83v at 8ohm isn't bad though. Can you post the harmonic distortion tab? Pick all harmonics up to 5th.
Here is prediction without extension duct:
Nice work!
Your measurement is tracking the prediction as it is down -5dB from 50Hz at 35Hz. You may have some room modes going on around 80-100hz that is causing those dips. The sensitivity I can't tell unless you measure how far away the mic is and wire it 2ohms (series within ea driver and parallel between drivers). 100dB with. 2.83v at 8ohm isn't bad though. Can you post the harmonic distortion tab? Pick all harmonics up to 5th.
Here is prediction without extension duct:
Xrk971,
Much thanks to you, Tb46 and the rest of guys for making this project possible.Working and this project I learn a few thanks that i will keep in mind for my next project.
Lawbiding,
You are welcome! Thanks for following thru to a build. Often times we help folks with designs that never get realized. Hope you enjoy the fruits of your creation. If you don't mind, please make a measurement with the extension duct in place at 2.83v and 1m with sub flat on ground. Take data from 10Hz to 2kHz without any filters in place so we can see predicted vs measured data.
Thanks
X
If you can't go outside then make a very low amplitude measurement with mic at plane of duct is ok.
You are welcome! Thanks for following thru to a build. Often times we help folks with designs that never get realized. Hope you enjoy the fruits of your creation. If you don't mind, please make a measurement with the extension duct in place at 2.83v and 1m with sub flat on ground. Take data from 10Hz to 2kHz without any filters in place so we can see predicted vs measured data.
Thanks
X
If you can't go outside then make a very low amplitude measurement with mic at plane of duct is ok.
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Like I said before i don't like wasting people time.
I want do two more project with your of cause,one for my computer using two small drivers and one for my girl friend using a 1260w or 1262w driver for her van.
This what i want to build for my computer with a built in plate amp. I will ask Tb46 for the measurements to the drawing.
For the 1260w or 1262w i want a design that put out a lot for spl. 38hz to 80-150hz.
The 1260w is the Infinity driver right? I have designed a PP slot loaded box for that too - nice driver and very inexpensive.
I am not sure how this design is supposed to work - maybe Tb46 can help to explain and I can model it. It looks like a push pull 4th order bandpass with a TL? Interesting though.
For desktop speaker look at 0.4x mini Karlsonator I designed. Sabaspeed just made a set and really likes them (along with a ton of other people).
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds-112.html#post4136648
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It probably could and I can run a sim but then it would be a sub and not a full range speaker. Is that what you want want - a sub?
Hi xrk971,
I'm interested in the MCM 55-2421 in a Karlsonator sub too. Maybe one of the little Vifa TC9FDs could be added to fill in the upper end? It is interesting, that this driver will actually work in your PPSL_Slot_Vented enclosures. I'll attach a few comments/link/Zaph's TS by sreten:
***************************
"http://www.diyaudio.com/forums/subwoofers/251016-cheap-sub-fantastick-results-9.html
17th February 2014, 08:58 PM #18 by sreten
Hi,
FWIW the excellent MCM drivers really will go into tiny sealed well stuffed cabinets and give a well damped slow 2nd order roll-off that if it matches your room gain well gives deep bass.
rgds, sreten.
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
-------------------------------------------------
22nd February 2014, 11:20 PM Post #85 by sreten
Join Date: Nov 2003
Location: Brighton UK Hi,
measured (courtesy of Zaph for the MCM 55-2421) vs claimed parameters :
Fs= 30.95 | 26
Qms= 12.2863 | 14
Qes= 0.2365 | 0.22
Qts= 0.2320 | 0.22
Vas= 23.88 | 30.5
SPL= 86.59 | 87
Re= 3.4 | 3.4
Le= 2.42 | 2.47
BL= 13.15 | 13
Xmax= 16mm P-P | 16
The TB version of the MCM driver does 12mm / 24mm p-p and is a better driver, as it should be as it costs a lot more.
Quick modeling indicates vented / PR's immediately.
However FWIW optimum sealed volume is 3L ! for a Qbox of 0.7, and -3dB at 90Hz, pretty useless. Going to Qbox = 0.5 is 7L with -3dB at 100Hz, but you get more low bass albeit still rolled off.
14L / 0.5cuft per driver gives a Qbox of 0.4.
21L / 0.75cuft per driver doesn't really help.
Given you go for 10L and a Qbox of 0.44 which is as sensible as anything else -3dB is 100Hz.
But ignore that for a a sub. Relative to 100Hz its - 5dB at 50Hz and - 10dB at 32Hz, nice.
The rolloff is very room gain friendly.
If you oversize the boxes its not a disaster at all, but doesn't make much difference. 0.75cuft for 2 drivers is as good as 1.5cuft for 2 drivers.
rgds, sreten.
---------------------------------------------------
23rd February 2014, 10:31 PM Post #91 sreten
Quote: "Using this driver in a sealed enclosure will require tons of eq and its sonics would be very questionable..."
Hi,
Yes Qts of 0.23 immediately recommends vented and not only that, an optimum volume of about 10L per driver with a 10" PR tuned to 30Hz, vented is hopeless.
However some people like very tight sealed boxes and in this thread that is what you have. The boxes are oversized but its not a disaster. In reality half volume, 0.75cuft for two drivers would be very near similar.
The response is poor, your looking at -3dB @ 100Hz.
However as a sub @ say 80Hz just knock off 4dB from the sensitivity. What you are left with is a slowroll off into the deep bass that can work wonders with good room gain and often does so to the users delight.
rgds, sreten."
**********************************
Looking forward to what you can get out of this driver in a Karlsonator. 🙂
Regards,
I'm interested in the MCM 55-2421 in a Karlsonator sub too. Maybe one of the little Vifa TC9FDs could be added to fill in the upper end? It is interesting, that this driver will actually work in your PPSL_Slot_Vented enclosures. I'll attach a few comments/link/Zaph's TS by sreten:
***************************
"http://www.diyaudio.com/forums/subwoofers/251016-cheap-sub-fantastick-results-9.html
17th February 2014, 08:58 PM #18 by sreten
Hi,
FWIW the excellent MCM drivers really will go into tiny sealed well stuffed cabinets and give a well damped slow 2nd order roll-off that if it matches your room gain well gives deep bass.
rgds, sreten.
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
-------------------------------------------------
22nd February 2014, 11:20 PM Post #85 by sreten
Join Date: Nov 2003
Location: Brighton UK Hi,
measured (courtesy of Zaph for the MCM 55-2421) vs claimed parameters :
Fs= 30.95 | 26
Qms= 12.2863 | 14
Qes= 0.2365 | 0.22
Qts= 0.2320 | 0.22
Vas= 23.88 | 30.5
SPL= 86.59 | 87
Re= 3.4 | 3.4
Le= 2.42 | 2.47
BL= 13.15 | 13
Xmax= 16mm P-P | 16
The TB version of the MCM driver does 12mm / 24mm p-p and is a better driver, as it should be as it costs a lot more.
Quick modeling indicates vented / PR's immediately.
However FWIW optimum sealed volume is 3L ! for a Qbox of 0.7, and -3dB at 90Hz, pretty useless. Going to Qbox = 0.5 is 7L with -3dB at 100Hz, but you get more low bass albeit still rolled off.
14L / 0.5cuft per driver gives a Qbox of 0.4.
21L / 0.75cuft per driver doesn't really help.
Given you go for 10L and a Qbox of 0.44 which is as sensible as anything else -3dB is 100Hz.
But ignore that for a a sub. Relative to 100Hz its - 5dB at 50Hz and - 10dB at 32Hz, nice.
The rolloff is very room gain friendly.
If you oversize the boxes its not a disaster at all, but doesn't make much difference. 0.75cuft for 2 drivers is as good as 1.5cuft for 2 drivers.
rgds, sreten.
---------------------------------------------------
23rd February 2014, 10:31 PM Post #91 sreten
Quote: "Using this driver in a sealed enclosure will require tons of eq and its sonics would be very questionable..."
Hi,
Yes Qts of 0.23 immediately recommends vented and not only that, an optimum volume of about 10L per driver with a 10" PR tuned to 30Hz, vented is hopeless.
However some people like very tight sealed boxes and in this thread that is what you have. The boxes are oversized but its not a disaster. In reality half volume, 0.75cuft for two drivers would be very near similar.
The response is poor, your looking at -3dB @ 100Hz.
However as a sub @ say 80Hz just knock off 4dB from the sensitivity. What you are left with is a slowroll off into the deep bass that can work wonders with good room gain and often does so to the users delight.
rgds, sreten."
**********************************
Looking forward to what you can get out of this driver in a Karlsonator. 🙂
Regards,
Tb46,
Not sure what Sreten was trying to say but I have sim'd this with Zaph's measured values and it looks great. You even drew plans for it remember?
http://www.diyaudio.com/forums/subwoofers/258433-light-air-slot-loaded-band-pass-sub-7.html#post3994894
A low Qts driver with low fs works very well in a slot loaded bandpass with sufficiently long vents. Not practical as a bass reflex but lends itself to a PPSL bandpass cabinet very well.
Predicted perf (corner placement):
Looks very nice to me for most home audio applications.
Not sure what Sreten was trying to say but I have sim'd this with Zaph's measured values and it looks great. You even drew plans for it remember?
http://www.diyaudio.com/forums/subwoofers/258433-light-air-slot-loaded-band-pass-sub-7.html#post3994894
A low Qts driver with low fs works very well in a slot loaded bandpass with sufficiently long vents. Not practical as a bass reflex but lends itself to a PPSL bandpass cabinet very well.
Predicted perf (corner placement):
Looks very nice to me for most home audio applications.
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Tb46,
Not sure what Sreten was trying to say but I have sim'd this with Zaph's measured values and it looks great. You even drew plans for it remember?
http://www.diyaudio.com/forums/subwoofers/258433-light-air-slot-loaded-band-pass-sub-7.html#post3994894
A low Qts driver with low fs works very well in a slot loaded bandpass with sufficiently long vents. Not practical as a bass reflex but lends itself to a PPSL bandpass cabinet very well.
Predicted perf (corner placement):
Looks very nice to me for most home audio applications.
I like it. Nice
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Hi xrk971,
Yes, I remember the "Light as Air..." thread. I never finished the drawing(s) w/ dimensions.
I understand sreten to say that the 55-2421 will indeed work in a sealed box w/ the proper low pass filter, and considering room gain. An interesting viewpoint, and as far as I'm concerned quite correct.
Would the 55-2421 Karlsonator be similar to the size for the Fostex FE206e?
Regards,
Yes, I remember the "Light as Air..." thread. I never finished the drawing(s) w/ dimensions.
I understand sreten to say that the 55-2421 will indeed work in a sealed box w/ the proper low pass filter, and considering room gain. An interesting viewpoint, and as far as I'm concerned quite correct.
Would the 55-2421 Karlsonator be similar to the size for the Fostex FE206e?
Regards,
Amazon is also selling for $59 - might be from same vendor. Is this a good driver? I also like the Infinity 1260w.
It is similar to the 1260w with 50 more watt then the 1260w.
Xrk971
Can you tell me know which driver works better in a tapped horn at f3 38hz
Thanks.