Hi,
Pay your money and take your choice. FWIW the MCM's
will work in tiny cabinets and 1.5 cuft for 2 is too big for
sealed. Sealed for 2 I'd suggest 0.5 to 0.75 cuft with
1 cuft as as point beyond which there is no point at all.
http://www.diyaudio.com/forums/subwoofers/80138-sillys-1st-sub-8-mcm-55-2421-a.html
rgds, sreten.
Pay your money and take your choice. FWIW the MCM's
will work in tiny cabinets and 1.5 cuft for 2 is too big for
sealed. Sealed for 2 I'd suggest 0.5 to 0.75 cuft with
1 cuft as as point beyond which there is no point at all.
http://www.diyaudio.com/forums/subwoofers/80138-sillys-1st-sub-8-mcm-55-2421-a.html
rgds, sreten.
Excellent sreten !!
Originally, I had projected a ported design for Byrons sub and that is why the box is rather large at 1.75 to 2.0 cubic feet for the two drivers.
But as it turned out for the size of room that they are used in the bass extension from the port would have been overkill, and, as a sealed system it would have a better transient characteristics anyhow.
So, The ports were never employed but could be added if he chooses to do so.
Here are the screen shots of the ported design simulations that I had done for the process of this build.
The first photo of Winlsd is the very First one that I came up with and I don't know if I still have the rest of them.
Then I used the Spreadsheet version to get the finer details.
I know I did some closed box sim's too but I don't know where I put them as this was basically the final design.
Enjoy !!
jer 🙂
Originally, I had projected a ported design for Byrons sub and that is why the box is rather large at 1.75 to 2.0 cubic feet for the two drivers.
But as it turned out for the size of room that they are used in the bass extension from the port would have been overkill, and, as a sealed system it would have a better transient characteristics anyhow.
So, The ports were never employed but could be added if he chooses to do so.
Here are the screen shots of the ported design simulations that I had done for the process of this build.
The first photo of Winlsd is the very First one that I came up with and I don't know if I still have the rest of them.
Then I used the Spreadsheet version to get the finer details.
I know I did some closed box sim's too but I don't know where I put them as this was basically the final design.
Enjoy !!
jer 🙂
Attachments
Hi,
measured (courtesy of Zaph) vs claimed parameters :
Fs=30.95 | 26
Qms=12.2863 | 14
Qes=0.2365 | 0.22
Qts=0.2320 | 0.22
Vas=23.88 l 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.
measured (courtesy of Zaph) vs claimed parameters :
Fs=30.95 | 26
Qms=12.2863 | 14
Qes=0.2365 | 0.22
Qts=0.2320 | 0.22
Vas=23.88 l 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.
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Thank you very much sir for all your contribution here , I can can appreciate someone who contributes there ideas instead of those who only say your wrong in your approach and give no data to support there claim. And to be perfectly honest I built these subs with the intent of porting them but wanted to listen to them first sealed because Im into exact reproduction of music sound rather than exaggerator bass and liked them so much I elected to leave them sealed.
Its low QTS and FS , makes its a perfect choice for a vented enclosure and still have excellent speed in a small enclosure, remember the lower the qts the faster the cone can respond. Best drivers for sealed enclosures have a Qts in the .4-.6 range, you will have to go with a Larger enclosures for sure to get a flat response , best , as larger enclosures are better than small due also to less dynamic compression.
Using this driver in a sealed enclosure will require tons of eq and its sonics would be very questionable...
Using this driver in a sealed enclosure will require tons of eq and its sonics would be very questionable...
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Oh Okay, Yes I understand this.
Thank you for reminding me of that.
As I had stated earlier this design was meant to be a ported design.
But, it was not employed as it was plenty for the smaller room that it was used in.
Cheers!!
jer 🙂
Thank you for reminding me of that.
As I had stated earlier this design was meant to be a ported design.
But, it was not employed as it was plenty for the smaller room that it was used in.
Cheers!!
jer 🙂
Last edited:
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.
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Exactly Right and that was the result of leaving it on ported, now granted putting them in a much larger room you defiantly port them. Many people are missing this . Room size plays a significant roll in woofer reaction that's why I stated the room size I built them for in the first #1 post . There is no such thing as a sub-woofer that good for any room size .
Hi all,
You can always increase the Re of the driver with a serial resistor or multiple drivers in series to lower the -3dB point in larger closed enclosures.
You can always increase the Re of the driver with a serial resistor or multiple drivers in series to lower the -3dB point in larger closed enclosures.
Yes, This is what I had expected.
I am not able to hear this system yet or able to do any measurements at this time as I am in Michigan.
But when I do mange to get down to Tennessee I will take my measuring tools with me and post the results here.
Byron wanted a nice and tight high transient bass system and it does deliver that by his descriptions.
If it were to be in his living space that is much bigger then I would opt to install the port's.
In the ported system I did the best I could do to keep the box small with a low tuning in order to keep the group delay low, down to about 30Hz or so, as everything is a compromise.
In a few tests I have done using my RS sub I have found that there is a rise in THD as the box's gets smaller and with an open air driver setup having the lowest THD.
Therefore I didn't want to use an excessively smaller box as suggested, and the fact that it turned out they way it did as already stated is because it was supposed to be ported in the first place.
I have also read about the traits of smaller boxes elsewhere in this forum and I plan to do a full study on this sometime when I can get a few different sized test boxes made.
Ultimately I personally was going to build a Dipole system but I could get my hands on the 16 drivers that I needed for my system.
I once had a 6 X 6.5" dipole and that worked great but I wanted something a little bigger for my ESL's but that is another story and thread.
The tops were meant to be ported as well and we just got done discussing this on the phone.
He says that he feels that ports should be added, as he is running those fullrange, and that they could do with a heavier bottom end.
That is what the ports will provide for him when he is not using the sub's.
All he has to do is added them.
The aluminium MCM cones have a very low THD just like the Dayton DA 175's but only a little smaller in diameter (1/2") as well as a lower cost.
I have found the THD curves to those and for the money they are Great performers and are very clean.
Most of the info I found is at the Zaph website and one other site that had a whole bunch of drivers that were tested with THD curves.
And also one other design that I dug up on the web that is nearly the same.
Just your typical WTW setup is all.
From what I could hear even on the phone the system as a whole is very clean and powerful!!!
Byron is new to DIYAudio.
But, He does know music very well and has a much larger system if he really wanted to rock out and make some noise for the neighbors!!! 😉
We got to talking one day and he told me that he wanted a system that was compact but could still rock out, But, still do it cleanly.
So, This is the system that I helped him to come up with without breaking the bank!
As I was still/am trying to talk him into building some ESL's. He,he,he,he 🙂
His First impression to me was that "These are the best and cleanest sounding system I have ever heard for the money I have into them!".
Even though it is comprised on some budget components it does show what could be done with the right selection of components while maintaining a low budget.
This particular system was a design that I had in the back of my mind for quite sometime to build for myself.
I couldn't be any more proud of the way it turned out for Byron without even getting to hear it for myself........Yet!!!
A lot of thought went in to this design.
With the only exception of not actually being able to measure it and tweek the crossover the way they should be in order to get the absolute most out of the drivers.
He has about 850watts of amplifier driving these things.
Two 300 watt plate amps, one in each sub, and, an amp that can produce at least 125 to 150 watts of clean power driving the top cabinets.
jer 🙂
I am not able to hear this system yet or able to do any measurements at this time as I am in Michigan.
But when I do mange to get down to Tennessee I will take my measuring tools with me and post the results here.
Byron wanted a nice and tight high transient bass system and it does deliver that by his descriptions.
If it were to be in his living space that is much bigger then I would opt to install the port's.
In the ported system I did the best I could do to keep the box small with a low tuning in order to keep the group delay low, down to about 30Hz or so, as everything is a compromise.
In a few tests I have done using my RS sub I have found that there is a rise in THD as the box's gets smaller and with an open air driver setup having the lowest THD.
Therefore I didn't want to use an excessively smaller box as suggested, and the fact that it turned out they way it did as already stated is because it was supposed to be ported in the first place.
I have also read about the traits of smaller boxes elsewhere in this forum and I plan to do a full study on this sometime when I can get a few different sized test boxes made.
Ultimately I personally was going to build a Dipole system but I could get my hands on the 16 drivers that I needed for my system.
I once had a 6 X 6.5" dipole and that worked great but I wanted something a little bigger for my ESL's but that is another story and thread.
The tops were meant to be ported as well and we just got done discussing this on the phone.
He says that he feels that ports should be added, as he is running those fullrange, and that they could do with a heavier bottom end.
That is what the ports will provide for him when he is not using the sub's.
All he has to do is added them.
The aluminium MCM cones have a very low THD just like the Dayton DA 175's but only a little smaller in diameter (1/2") as well as a lower cost.
I have found the THD curves to those and for the money they are Great performers and are very clean.
Most of the info I found is at the Zaph website and one other site that had a whole bunch of drivers that were tested with THD curves.
And also one other design that I dug up on the web that is nearly the same.
Just your typical WTW setup is all.
From what I could hear even on the phone the system as a whole is very clean and powerful!!!
Byron is new to DIYAudio.
But, He does know music very well and has a much larger system if he really wanted to rock out and make some noise for the neighbors!!! 😉
We got to talking one day and he told me that he wanted a system that was compact but could still rock out, But, still do it cleanly.
So, This is the system that I helped him to come up with without breaking the bank!
As I was still/am trying to talk him into building some ESL's. He,he,he,he 🙂
His First impression to me was that "These are the best and cleanest sounding system I have ever heard for the money I have into them!".
Even though it is comprised on some budget components it does show what could be done with the right selection of components while maintaining a low budget.
This particular system was a design that I had in the back of my mind for quite sometime to build for myself.
I couldn't be any more proud of the way it turned out for Byron without even getting to hear it for myself........Yet!!!
A lot of thought went in to this design.
With the only exception of not actually being able to measure it and tweek the crossover the way they should be in order to get the absolute most out of the drivers.
He has about 850watts of amplifier driving these things.
Two 300 watt plate amps, one in each sub, and, an amp that can produce at least 125 to 150 watts of clean power driving the top cabinets.
jer 🙂
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The 850 amp runs the sub's with preamp db and the main power is put into the 2 minitowers and center channel the rest goes to 2 rear speakers for a 7.0 surround system 🙂
Running some number on this MCM driver, .5 cu ft per driver is a bit tight for good Sub bass, output IMO, did you guys actually measure the subs built with these drivers and it's 84db/1watt/m could be a problem unless running at least 8 for subs ..
You need a -3db of 28hz to even consider them subs...
You need a -3db of 28hz to even consider them subs...
No wayne no numbers have been run on them, I don't run numbers I have ears, and that is why I built them for my listening pleasure. Too many people get caught up in the number game, the program's are only as good as the writer's own test results who wrote the program and as my friend Gerald has pointed out these programs are not always accurate. You can manipulate the speakers in many ways to better the sound quality, we have done this successfully now if you don't want to follow this plan along your free to do so but please don't fault my speakers I have the speakers and you do not , I have built the cabinets @ 1.53 qft. and can personally tell you they thrill the hell out of me as I have had many subs and these surpass them all. I got big power to throw at them and @ 28 hz db is not a problem and I have no reason to lie. My only objective was to share my result's to anyone wanted a good sub for little money 🙂
Is that 1.53 per driver ...? Good audio is a delicate balance between subjective and objective observation, since we cant hear what you have, measurements gives us a window into what you are listening to, it's not meant as a put down...
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