Glad to answer, I'm sure many will find this painful.
When the speaker is out of the box, there is only one peak.
In the box - that same peak gets pushed (like a air balloon) into the M.
It does make sense that the top of the M should be level and the bottom of the M is where the peak was.
ALWASY connect volt meter to speaker leads! Easy to remember.
When the speaker is out of the box, there is only one peak.
In the box - that same peak gets pushed (like a air balloon) into the M.
It does make sense that the top of the M should be level and the bottom of the M is where the peak was.
ALWASY connect volt meter to speaker leads! Easy to remember.
This forum appears to get energy for folded horns, TL's T-TQWTs; this box may be too humdrum for such an advanced group.
That said, it is compact, fun and easy to build (8ohm also).
Randy, visited your site, I assume this is for the turntable/stereo?
I saw some very strange comments/feedback.....
That said, it is compact, fun and easy to build (8ohm also).
Randy, visited your site, I assume this is for the turntable/stereo?
I saw some very strange comments/feedback.....
55-2421 is probably one of my favorite sub drivers of all time.
I agree with you, it's hardly appropriate for isobaric
There are a couple things you might try, to make it more appropriate for isobaric duty:
#1 - raise the qes with a resistor
#2 - raise the qms with mass loading of the cone
I did both with a project using the 55-2421. The final response came out pretty good, and the sub itself is pretty handsome.
On the downside, the efficiency ends up very very very low, so you better bring up a big amp.
IMHO, the 55-2421 is best suited for front-loaded horns, bandpass boxes and tapped horns. In the car, it works nice in a sealed box thanks to cabin gain, but it needs some EQ to bring up the bottom end.
It's completely unsuitable in a sealed box in the home, because the F3 ends up in the triple digits due to the very low QTS
If anyone has built this isobaric box, finds the bass lacking, and owns a big amplifier, I'd consider trying the resistor trick. I have it documented on these forums somewhere, this project was back in 2008 or 2009 iirc. Brian Steele has a calculator on his site for figuring out RE, and Dan Wiggins had some papers on how to do this at adireaudio.com
Thank you Patrick for your input.
I never encounter any lack of bass issues; quite the little monster. I've use 60 watt stereo amps (bridged) and inexpensive plate amps. They all had plenty of output.
The one my buddy has, we used the $119 Dayton with the "B" it sounded great and he's thanking me every time I see him. The B is 40Hz bass boost.
If someone does build one, it will need to be a solid box, with attention to a well cut tunnel,,,,,if if it leaks all over, I don't think it would work.
I never encounter any lack of bass issues; quite the little monster. I've use 60 watt stereo amps (bridged) and inexpensive plate amps. They all had plenty of output.
The one my buddy has, we used the $119 Dayton with the "B" it sounded great and he's thanking me every time I see him. The B is 40Hz bass boost.
If someone does build one, it will need to be a solid box, with attention to a well cut tunnel,,,,,if if it leaks all over, I don't think it would work.
This forum appears to get energy for folded horns, TL's T-TQWTs; this box may be too humdrum for such an advanced group.
That said, it is compact, fun and easy to build (8ohm also).
Randy, visited your site, I assume this is for the turntable/stereo?
I saw some very strange comments/feedback.....
Yeah, when I linked to it originally I only had stereo info, the coffee projects were added later.
Turntable was a while ago, and it is now collecting dust because I'm too lazy to spin vinyl.
I did delete the spam comments from the blog, there was one where I had NO idea what his point was
You probably noticed that I have not updated in a while, but its a nice way to document projects.As for this project, I am still torn between your sub and an H Frame with a alpha 15a.
This sub is intended for music only, and I don't listen at high volumes, so I don't need high output. I would be happy if it reached into the low 30's, with a moderate output.
I think your sub may have more output, while the h frame may be faster, but I obviously really don't know if this is true or not.
Cost is basically the same, h frame would be a little easier build.
Randy
Patrick,
I saw a pic on another thread.... looks like you may have 55-2421's, how many do you have?
The thought here was one sounded great in a simple BR, but would bottom out the 1st "explosion". Yikes!
By adding 2nd in the 5" air tight tunnel, the power handling goes way up, suitable for HT.
I remember a lot of people saying they have these laying around, I suggest they give it a try.
The box here was double layer 1/2" MDF ($25 bucks).
I saw a pic on another thread.... looks like you may have 55-2421's, how many do you have?
The thought here was one sounded great in a simple BR, but would bottom out the 1st "explosion". Yikes!
By adding 2nd in the 5" air tight tunnel, the power handling goes way up, suitable for HT.
I remember a lot of people saying they have these laying around, I suggest they give it a try.
The box here was double layer 1/2" MDF ($25 bucks).
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5.1
Hooked this up yesterday; very happy, the box sounded great, a very defined, deep base.
[huge, huge, HT/Pool Table room, the HT is on the "wrong" side]
By just popping the outside cone with knuckle, there is a deep bass sound; not a "Boom" a deep "Biff". Easy to hear the bass coming from the port.
I liked the improvements, a small sheet on damping material (which is pretty light/see thru) and the cork liner. btw, this box did not have bracing, but is 1" MDF.
I would say the drawbacks are:
* Not going to handle a Gobs-of-Power, and/or would need to use low pass filter or limiter. I.e. huge motor with a floppy cone suspension.
[although the plate amp is 200 watt]
* The weight, it just looks small, it's heavy - the slot is handy for lifting.
* Would need pretty good carpenter/router skills, the tunnel should be air tight.
The 5 channel amp is a RMB 1085
Hooked this up yesterday; very happy, the box sounded great, a very defined, deep base.
[huge, huge, HT/Pool Table room, the HT is on the "wrong" side]
By just popping the outside cone with knuckle, there is a deep bass sound; not a "Boom" a deep "Biff". Easy to hear the bass coming from the port.
I liked the improvements, a small sheet on damping material (which is pretty light/see thru) and the cork liner. btw, this box did not have bracing, but is 1" MDF.
I would say the drawbacks are:
* Not going to handle a Gobs-of-Power, and/or would need to use low pass filter or limiter. I.e. huge motor with a floppy cone suspension.
[although the plate amp is 200 watt]
* The weight, it just looks small, it's heavy - the slot is handy for lifting.
* Would need pretty good carpenter/router skills, the tunnel should be air tight.
The 5 channel amp is a RMB 1085
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55-2421 - ISO Box with tunnel
Well finally....here's the in-room response: factory rebooted the processor, and there's no boost or equalization. The only filter is @ 100hz, 12 db (or18db) per octave.
As we can see, the usable range is short but sweet!
One major plus is that it does not require a lot of power, but will handle quite a bit with a subsonic filter.
2nd plus - the MCM 55-2421 is $29.
3rd the ISO box is compact.
Well finally....here's the in-room response: factory rebooted the processor, and there's no boost or equalization. The only filter is @ 100hz, 12 db (or18db) per octave.
As we can see, the usable range is short but sweet!
One major plus is that it does not require a lot of power, but will handle quite a bit with a subsonic filter.
2nd plus - the MCM 55-2421 is $29.
3rd the ISO box is compact.
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ALSO - this single box plan over at PE works nicely also:
[not easy to find]
Super small sub box - Techtalk Speaker Building, Audio, Video Discussion Forum
[not easy to find]
Super small sub box - Techtalk Speaker Building, Audio, Video Discussion Forum
Hi Oliver,
Post # 174, that's it, well there's three and I gave one to a buddy, but they are the same. It is hard to believe the 15db roll at 45hz, but removed all the filters and didn't hear any difference to the bass. Which could be perfect for someone starting off and wanted a sub and all they had to work with was RCA, Y connectors and and extra 60watt receiver.
That said I picked up a Dayon SA1000, it has some eq features built in, but as mention above, didn't see/hear much difference when adjusting them.
So yes sending 500 watts to two MCM 55-2421 (switched on the sub-sonic filter), the cone movement is not bad at all, less than 1/2", at a nice HT level.
The setting for the front L-C-R -- 40hz (or pass-thru) and the MCM Iso box fills in the rest of the lower end.
One more thought, there are several boxes here, so far this is working the best, better than the 10" Alpine and an Anarchy tower, they both have similar narrow peaks at 35hz.
I know the answer here, but going to ask anyway, can I check the MCM box, with a db meter and generator, outside away from the house? Simply plot the readings one by one 20hz to 80hz?
***Rated power output: 497 watts into 8 ohms, 950 watts into 4 ohms • Signal to noise ratio: 98 dB A-weighted • Efficiency: 86% • Input impedance: 12K ohms • Subsonic filter: -3 dB @ 18 Hz, Q=0.8 • Bass boost: +3 dB @ 25 Hz, Q=1.4 • High pass output: -3 dB @ 80 Hz, 12 dB/octave • Low pass adjustment: 30-200 Hz • Phase adjustment: 0°–180° • Parametric EQ frequency: 18–80 Hz • Bandwidth: 0.1–1.0 Q • Level: -14.5 dB to +6 dB •
Post # 174, that's it, well there's three and I gave one to a buddy, but they are the same. It is hard to believe the 15db roll at 45hz, but removed all the filters and didn't hear any difference to the bass. Which could be perfect for someone starting off and wanted a sub and all they had to work with was RCA, Y connectors and and extra 60watt receiver.
That said I picked up a Dayon SA1000, it has some eq features built in, but as mention above, didn't see/hear much difference when adjusting them.
So yes sending 500 watts to two MCM 55-2421 (switched on the sub-sonic filter), the cone movement is not bad at all, less than 1/2", at a nice HT level.
The setting for the front L-C-R -- 40hz (or pass-thru) and the MCM Iso box fills in the rest of the lower end.
One more thought, there are several boxes here, so far this is working the best, better than the 10" Alpine and an Anarchy tower, they both have similar narrow peaks at 35hz.
I know the answer here, but going to ask anyway, can I check the MCM box, with a db meter and generator, outside away from the house? Simply plot the readings one by one 20hz to 80hz?
***Rated power output: 497 watts into 8 ohms, 950 watts into 4 ohms • Signal to noise ratio: 98 dB A-weighted • Efficiency: 86% • Input impedance: 12K ohms • Subsonic filter: -3 dB @ 18 Hz, Q=0.8 • Bass boost: +3 dB @ 25 Hz, Q=1.4 • High pass output: -3 dB @ 80 Hz, 12 dB/octave • Low pass adjustment: 30-200 Hz • Phase adjustment: 0°–180° • Parametric EQ frequency: 18–80 Hz • Bandwidth: 0.1–1.0 Q • Level: -14.5 dB to +6 dB •
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Another question, the box does not have any fill, what if it was stuffed it up?
Would it be enough to lower the peak?
Thanks!!
Would it be enough to lower the peak?
Thanks!!
not likely. the peak is a function of the design. stuffing it, or even heavily lining it, will only serve to lower upper band response/peaks. could also muffle some nasties that may be making their way out of the port (ie motor noise, etc) heavy lining or stuffing could also reduce system sensitivity across the band.
Hi ODougbo,
For measurements: maybe using REW would be easier? But, the method you describe would work, you have to be aware of reflective surfaces, sometimes you can get better measurement using a wall, or even a solid external corner.
Post #195: "...the box does not have any fill, what if it was stuffed it up?"
I made an example simulation in Hornresp, you can import it, and play around w/ the volumes, dimensions and filling. I did not try to calculate your box, or duct, etc. Usually you don't need filling in subwoofers, but in this case: filling will work if done correctly.
Regards,
For measurements: maybe using REW would be easier? But, the method you describe would work, you have to be aware of reflective surfaces, sometimes you can get better measurement using a wall, or even a solid external corner.
Post #195: "...the box does not have any fill, what if it was stuffed it up?"
I made an example simulation in Hornresp, you can import it, and play around w/ the volumes, dimensions and filling. I did not try to calculate your box, or duct, etc. Usually you don't need filling in subwoofers, but in this case: filling will work if done correctly.
Regards,
Attachments
Thanks for posting that Oliver, 44liters is a very reasonable size.
Found the 2nd Iso box and now it's in the shop with the back off, gluing cork board pieces to the inside with construction glue. This ploy has been working well for me, by stiffening the walls a bit and any removing ringing sounds. Also have a few bags of light fill.
Here's another concept design, I believe this may work better than simply putting two of the woofer in a BR box, but if not, it's still very compact:
Found the 2nd Iso box and now it's in the shop with the back off, gluing cork board pieces to the inside with construction glue. This ploy has been working well for me, by stiffening the walls a bit and any removing ringing sounds. Also have a few bags of light fill.
Here's another concept design, I believe this may work better than simply putting two of the woofer in a BR box, but if not, it's still very compact:
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Hi ODougbo,
You probably are aware of this, but for a symmetrical layout as in Post #198 you don't need a center divider board in the port.
Cork board works, but it will reduce the internal volume (about by the volume taken up by the cork). Some felt would be better, even thin carpet underlayment felt will work.
If you are interested in another concept take a look @ xrk971's nice ideas here:
http://www.diyaudio.com/forums/subwoofers/264737-pp-slot-loaded-sub-alpine-swr-12d2.htm
I added a number of sketches, e.g.: Posts #177/187/192/195/223. xrk971 added a bunch of AkAbak simulations, e.g.: Post #185. lawbiding build this there are build pictures throughout the thread, e.g.: Post #254. That should give you an idea, either way it's an interesting thread with all kinds of enclosure ideas.
Regards,
You probably are aware of this, but for a symmetrical layout as in Post #198 you don't need a center divider board in the port.
Cork board works, but it will reduce the internal volume (about by the volume taken up by the cork). Some felt would be better, even thin carpet underlayment felt will work.
If you are interested in another concept take a look @ xrk971's nice ideas here:
http://www.diyaudio.com/forums/subwoofers/264737-pp-slot-loaded-sub-alpine-swr-12d2.htm
I added a number of sketches, e.g.: Posts #177/187/192/195/223. xrk971 added a bunch of AkAbak simulations, e.g.: Post #185. lawbiding build this there are build pictures throughout the thread, e.g.: Post #254. That should give you an idea, either way it's an interesting thread with all kinds of enclosure ideas.
Regards,
Thanks Oliver,
Well I certainly wouldn't want anyone to build the MCM ISO box unless they know what they're getting into. I guess it would be considered a small speaker in a big box ploy with a huge peak from 29 to 40hz. The part that IS strange... is the wonderful, rich tone, deep bass that pours out of it effortlessly. There are no sour notes, ringging, etc. And of course they're fun to build.
The box from the PE site, right I've run BR sims in WinIsd with this woofer many times, but that little single cube really works well (I have one installed at another location).
The strategy is straightforward enough, simply double it -- it will end up 2 inches taller and use a couple extra slabs of wood.
* Having problems with the subwoofer link.
Well I certainly wouldn't want anyone to build the MCM ISO box unless they know what they're getting into. I guess it would be considered a small speaker in a big box ploy with a huge peak from 29 to 40hz. The part that IS strange... is the wonderful, rich tone, deep bass that pours out of it effortlessly. There are no sour notes, ringging, etc. And of course they're fun to build.
The box from the PE site, right I've run BR sims in WinIsd with this woofer many times, but that little single cube really works well (I have one installed at another location).
The strategy is straightforward enough, simply double it -- it will end up 2 inches taller and use a couple extra slabs of wood.
* Having problems with the subwoofer link.
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