Looking for Opinions on Setup using 4 Sealed Mach 5 FTW 21" Sub Woofers

[lovinthehd]

With all due respect, I dont think you have read all my posts.

I am not putting all 4 subs in 1 spot. All 4 boxes will be in different spots. 2 across the front of the room and the other 2 behind the listending area(Couch). I may move them around a bit once setup, but will see how it sounds first

The modeling has nothing to do with where I am placing the subs. I modeled one to see the SPL graph and then the way winisd works I had to muliply the cubic foot for the box by 4 to 25 cubic feet to get a proper SPL graph for 4 subs so I could see the output of 4 subs vs 1.

To answer your other questionabout the CVR amp, I had seen a youtube video of a couple guys putting that amp on an amp dyno and it was bang on to what it was rated for. I wll try and find a link to share to that as it was a while ago I seen it. If you read up on CVR amps, they do not dissapoint and are the best bang for your buck right now.

I am also not plugging it in to my wall socket, as Im sure, I would be tripping the 15 amp breaker. The amp will be located in another room right beside my hydro panel so I dont have to hear the noisy fans during quiet parts of the movie.

Im going to wire it directly into the hydro panel and feed it 220 volts and use a double 30 amp breaker so it will have plenty of juice.

Yes, I have read all the posts. That's why I said don't model the sub as if it is in one box in one location, that will yield different results than four single boxes, especially as placed throughout a room. I get what you're trying for, just saying that's just not going to get you there.

CVR amp of that output tested was at one or four channels driven at same time or what?

 

[Allen Vos]

Yes, I have read all the posts. That's why I said don't model the sub as if it is in one box in one location, that will yield different results than four single boxes, especially as placed throughout a room. I get what you're trying for, just saying that's just not going to get you there.

CVR amp of that output tested was at one or four channels driven at same time or what?

Of course. I know the software is not meant for that, but I only wanted to see the SPL charts for 1 vs 4 is all.

I was only moddelling 1 because of what TLS had said , so I wanted to make sure and try modelling just 1 to make sure that sub was suitable in a sealed box.

I do remember the amp test and it was with all 4 channels being driven

I had looked into some other amps, the berringer NX6000 and a Sinbosen.

The berringer failed miserbly trying to drive a sealed sub at low frequencies and the sinbosen was only putting out about 75% of what it was advertised.

Everyone seems to love and rave about the CVR amps in the DIY sub builds.

I could go with a quality north american made rack amp, but they are pricey.

 

[lovinthehd]

Of course. I know the software is not meant for that, but I only wanted to see the SPL charts for 1 vs 4 is all.

I was only moddelling 1 because of what TLS had said , so I wanted to make sure and try modelling just 1 to make sure that sub was suitable in a sealed box.

I do remember the amp test and it was with all 4 channels being driven

I had looked into some other amps, the berringer NX6000 and a Sinbosen.

The berringer failed miserbly trying to drive a sealed sub at low frequencies and the sinbosen was only putting out about 75% of what it was advertised.

Everyone seems to love and rave about the CVR amps in the DIY sub builds.

I could go with a quality north american made rack amp, but they are pricey.

Interesting, just haven't heard about CVR and if you can, would appreciate some links. Haven't dwelled on the avsforum diy board for a long while, built most of my subs 10 years ago now. In any case, I'd still rather run multiple amps Never heard of Sinbosen. Behringer sure, and have not used one of those due sloppy specs as a primary reason, but they bench test reasonably well (but not to marketing spec).

75% of an amp's output in what way? How is the percentage determined? Just not a good way to compare amps (i.e. via "percentage").

 

[Allen Vos]

Interesting, just haven't heard about CVR and if you can, would appreciate some links. Haven't dwelled on the avsforum diy board for a long while, built most of my subs 10 years ago now. In any case, I'd still rather run multiple amps Never heard of Sinbosen. Behringer sure, and have not used one of those due sloppy specs as a primary reason, but they bench test reasonably well (but not to marketing spec).

75% of an amp's output in what way? How is the percentage determined? Just not a good way to compare amps (i.e. via "percentage").

I will do my best to find some links for you. I can definetly post some links to CVR, sinbosen so you can have some more info on these.

I remeber with the berrringer amp, it was rated at 1200 watts RMS at a 4 ohm load and when pushed to 1200 watts at 25 HZ in a sealed application it fell hard and could only put about 600 watts of output .

the 75% output was just that. The amp could only produce 75 % of its rated output when loaded to low frequencies. For example, if the amp was rated at 1000 watts it would only push 750

I have a busy weekend but let me see if I book marked those CVR amp dyno videos and I will post them if I can find them

 

[lovinthehd]

the 75% output was just that. The amp could only produce 75 % of its rated output when loaded to low frequencies. For example, if the amp was rated at 1000 watts it would only push 750

Thanks, get back to me with the links you can find, I'd like that. No rush.

OTOH this is a good example of why a percentage isn't the best expression here. To gain a mere 3db SPL (a small increase) you'd need to go from 750w to 1500w. 750w to 1000w is a mere 1 dB (almost indistinguishable). Many amps come with "enthusiastic" specs from marketing....why we adore sites like Audioholics, ASR and Erin's for actual measurements. Even eq will eat up your amp's power advantages with boosting....

 

[Allen Vos]

I know it was mentioned about the sub over extending at low frequencies and that I had to be careful where I set my low pass frequency cut off at.

I have been playing with WINISD and have a much better understanding of it.

I have entered in all the MACH 5 FTW-21" driver specs.

The box is sealed at 6.2 cubic feet and I set it at 1200 watts as that is the max I will be putting to eash sub.

I have included the "Cone Excursion" graph and this is the conclusion I have come up with.

I have 23mm of cone travel at 5HZ
I have just over 25mm of cone travel at 4HZ
I have just over 29mm of cone travel at 3HZ

So, I feel it's a pretty safe bet to set my cutoff in my Mini DSP at 5HZ for these subs.

I am also planing on adding poly fill inside the box as well.

I know the poly fill makes the box act like a larger one, but I was wondering if adding poly fill would affect the cone travel(XMAX)?

Im guessing no, but it does not hurt to ask

Anyone care to Chyme in on this?

 

[TLS Guy]

View attachment 80021

I know it was mentioned about the sub over extending at low frequencies and that I had to be careful where I set my low pass frequency cut off at.

I have been playing with WINISD and have a much better understanding of it.

I have entered in all the MACH 5 FTW-21" driver specs.

The box is sealed at 6.2 cubic feet and I set it at 1200 watts as that is the max I will be putting to eash sub.

I have included the "Cone Excursion" graph and this is the conclusion I have come up with.

I have 23mm of cone travel at 5HZ
I have just over 25mm of cone travel at 4HZ
I have just over 29mm of cone travel at 3HZ

So, I feel it's a pretty safe bet to set my cutoff in my Mini DSP at 5HZ for these subs.

I am also planing on adding poly fill inside the box as well.

I know the poly fill makes the box act like a larger one, but I was wondering if adding poly fill would affect the cone travel(XMAX)?

Im guessing no, but it does not hurt to ask

Anyone care to Chyme in on this?

No, it won't but sealed subs need filling with poly fill, but don't compress it.

 

[TLS Guy]

View attachment 80021

I know it was mentioned about the sub over extending at low frequencies and that I had to be careful where I set my low pass frequency cut off at.

I have been playing with WINISD and have a much better understanding of it.

I have entered in all the MACH 5 FTW-21" driver specs.

The box is sealed at 6.2 cubic feet and I set it at 1200 watts as that is the max I will be putting to eash sub.

I have included the "Cone Excursion" graph and this is the conclusion I have come up with.

I have 23mm of cone travel at 5HZ
I have just over 25mm of cone travel at 4HZ
I have just over 29mm of cone travel at 3HZ

So, I feel it's a pretty safe bet to set my cutoff in my Mini DSP at 5HZ for these subs.

I am also planing on adding poly fill inside the box as well.

I know the poly fill makes the box act like a larger one, but I was wondering if adding poly fill would affect the cone travel(XMAX)?

Im guessing no, but it does not hurt to ask

Anyone care to Chyme in on this?

Here is the model I promised you for your drivers. Sorry it took a while, but my wife has had a difficult recovery, but doing better now.

Here is the model of the driver under discussion.

I have done this very carefully. The program used was Bass Box Pro. This is a highly regarded program and used by many professional designers.

It basically shows what I had surmised from my now 72 years of speaker designing and building spekers.

First of all, it seems to be a very capable driver, but it can not perform miracles and has to abide by natures physical laws.

So the highlights.

Bass Box pro, as expected indicates this driver is suitable for sealed application only.

The optimal sealed volume is 8.28 cu.ft. with heavy fill.

The native F3 is as expected about an octave above Fs. which is 39.54 Hz, which rounding it off is 40 Hz, exactly what I estimated. So the driver rolls of at 12 db. per octave as all sealed designs do. Therefore it is -12 db. at 20 Hz as expected. So a boost of 12 db. per octave needs to be applies below 40 Hz.

Now this driver has good excursion limits, but it starts to head towards xmax below 20 Hz as you would expect. At 20 Hz the driver will tolerate 200 watts of power, below that it starts to exceed X-max, by 15 Hz the driver is running out of cone displacement and output is falling off and the driver risking damage. So as I suspected the driver needs high passing at 20 Hz, which is its effective lower frequency limit, as I suspected.

So, in essence this is a very capable sub driver, but it does not perform the miracle of defying the laws of physics. However with capable amplification and proper high and low pass filter settings, it appears to be a very capable LF driver, which for its cost and size it should be.

 

[lovinthehd]

Here is the model I promised you for your drivers. Sorry it took a while, but my wife has had a difficult recovery, but doing better now.

Here is the model of the driver under discussion.

I have done this very carefully. The program used was Bass Box Pro. This is a highly regarded program and used by many professional designers.

It basically shows what I had surmised from my now 72 years of speaker designing and building spekers.

First of all, it seems to be a very capable driver, but it can not perform miracles and has to abide by natures physical laws.

So the highlights.

Bass Box pro, as expected indicates this driver is suitable for sealed application only.

The optimal sealed volume is 8.28 cu.ft. with heavy fill.

The native F3 is as expected about an octave above Fs. which is 39.54 Hz, which rounding it off is 40 Hz, exactly what I estimated. So the driver rolls of at 12 db. per octave as all sealed designs do. Therefore it is -12 db. at 20 Hz as expected. So a boost of 12 db. per octave needs to be applies below 40 Hz.

Now this driver has good excursion limits, but it starts to head towards xmax below 20 Hz as you would expect. At 20 Hz the driver will tolerate 200 watts of power, below that it starts to exceed X-max, by 15 Hz the driver is running out of cone displacement and output is falling off and the driver risking damage. So as I suspected the driver needs high passing at 20 Hz, which is its effective lower frequency limit, as I suspected.

So, in essence this is a very capable sub driver, but it does not perform the miracle of defying the laws of physics. However with capable amplification and proper high and low pass filter settings, it appears to be a very capable LF driver, which for its cost and size it should be.

Curious, how did you adjust for OP's desire vs your "optimal" solution for one box?

ps Glad to hear your wife's surgery went well so far...

 

[TLS Guy]

Curious, how did you adjust for OP's desire vs your "optimal" solution for one box?

ps Glad to hear your wife's surgery went well so far...

I don't quite understand your question. I modelled one diver in one box. However, you just double the box volume for two drivers, triple it for three and Quadruple it for four. However, with a driver that large, I think you would not use more than one driver per box, and certainly not more than two.

The optimal solution is actually essentially the only solution that is optimal, although for sealed you could make the box marginally smaller changing the outcome slightly, but not a lot. Making the box a smaller you affect the low end output, raising F3. Making the box bigger risks making cone excursions greater and risking over extension. It would therefore reduce output. In speaker designs getting the box volume optimal is key.

TL designs are much tougher and there are more issues to juggle.

For vented designs, getting the box volume correct is vital or the design will not work.


I appreciate your concern for my wife, she has an underlying issue the complicates the situation. I think she is turning the corner now she is three weeks out.

 

[lovinthehd]

I don't quite understand your question. I modelled one diver in one box. However, you just double the box volume for two drivers, triple it for three and Quadruple it for four. However, with a driver that large, I think you would not use more than one driver per box, and certainly not more than two.

The optimal solution is actually essentially the only solution that is optimal, although for sealed you could make the box marginally smaller changing the outcome slightly, but not a lot. Making the box a smaller you affect the low end output, raising F3. Making the box bigger risks making cone excursions greater and risking over extension. It would therefore reduce output. In speaker designs getting the box volume optimal is key.

TL designs are much tougher and there are more issues to juggle.

For vented designs, getting the box volume correct is vital or the design will not work.


I appreciate your concern for my wife, she has an underlying issue the complicates the situation. I think she is turning the corner now she is three weeks out.

How do you model the implementation of the multiple boxes involved here particularly?

 

[TLS Guy]

How do you model the implementation of the multiple boxes involved here particularly?

You don't need to. If you use 2 boxes the the max output will go up by 3db, if you use four it will be 6db. It won't change the FR or bass extension.