Monolith 13" vs 15" V2 (Measurement Discrepancies?)

[mj30250]

Greetings,

I currently use dual Hsu VTF-3 MK5 subs in my primary setup. I've recently adjusted their positioning using REW and have them fairly well optimized for reasonably good frequency response and output given a variety of placement limitations. I'm very pleased with how they sound, however, during low frequency playback at loud volumes (sub-25Hz or so) I find that port chuffing can intrude. I currently run them in EQ1 mode w/ 1 port plugged for maximum extension. I've been toying with the idea of moving to subs with large enclosures and more port area to help with ULF performance and have narrowed my options down to the Monolith 13" and 15" subs.

Per James' review, the 13" Monolith seems to out-perform the 15" at virtually all frequencies (at least with the ports open). However, in looking at Erin's reviews of each of these subs, his results are quite different. Now, I understand that there are some differences in how each reviewer measures and captures the data, so it's understandable that the numbers between both may not align precisely. However, while Erin's measurements agree with James' in that they show the 15" Monolith gives up ULF output to the newer, more powerful 13", once it reaches into the midbass, the 15" handily bests the 13". This is in stark contrast to James' findings.

This is taken from Erin's review of the 13" Monolith:

Per this table, we can see better ULF output from the 13", but once each sub rounds 30Hz, the 15" is getting twice as loud (or better).

Compare this to James' data:

Based on Erin's data I'm likely going with the 15" to maintain the better midbass output. Based on James' data the 13" is an easy winner virtually everywhere. Why such a discrepancy?

To throw another wrench into the equation, I can currently purchase the 15" on sale for a dramatically lower cost than the 13". The difference in price in purchasing two is over $1400 in favor of the 15". I'm also open to the possibility that I am missing something simple.

Thanks in advance!

 

[shadyJ]

Greetings,

I currently use dual Hsu VTF-3 MK5 subs in my primary setup. I've recently adjusted their positioning using REW and have them fairly well optimized for reasonably good frequency response and output given a variety of placement limitations. I'm very pleased with how they sound, however, during low frequency playback at loud volumes (sub-25Hz or so) I find that port chuffing can intrude. I currently run them in EQ1 mode w/ 1 port plugged for maximum extension. I've been toying with the idea of moving to subs with large enclosures and more port area to help with ULF performance and have narrowed my options down to the Monolith 13" and 15" subs.

Per James' review, the 13" Monolith seems to out-perform the 15" at virtually all frequencies (at least with the ports open). However, in looking at Erin's reviews of each of these subs, his results are quite different. Now, I understand that there are some differences in how each reviewer measures and captures the data, so it's understandable that the numbers between both may not align precisely. However, while Erin's measurements agree with James' in that they show the 15" Monolith gives up ULF output to the newer, more powerful 13", once it reaches into the midbass, the 15" handily bests the 13". This is in stark contrast to James' findings.

This is taken from Erin's review of the 13" Monolith:

View attachment 66311

Per this table, we can see better ULF output from the 13", but once each sub rounds 30Hz, the 15" is getting twice as loud (or better).

Compare this to James' data:

View attachment 66312

View attachment 66313

Based on Erin's data I'm likely going with the 15" to maintain the better midbass output. Based on James' data the 13" is an easy winner virtually everywhere. Why such a discrepancy?

To throw another wrench into the equation, I can currently purchase the 15" on sale for a dramatically lower cost than the 13". The difference in price in purchasing two is over $1400 in favor of the 15". I'm also open to the possibility that I am missing something simple.

Thanks in advance!

I can't explain the discrepancy between Erin and my own measurements. I don't think that the 15" has more mid-bass than the 13" though. The 13" has double the wattage. Also note that my own measurements for the 15" and monoprice's measurements are fairly close. You can't go wrong with either one, but I would say the 13" is the better value at non-sale prices, especially if you are interested in big mid-bass.

 

[mj30250]

Fair enough, thanks. It's definitely strange.

I would agree that based on your data, the 13" is the better sub overall, but the current sale pricing makes it prohibitive. For the price of two 13"s, three 15"s could be purchased. It doesn't look like Monoprice has had any significant sales on the 13" since it's been released. I'm sure they'll come around eventually.

 

[snakeeyes]

Think there was a monolith 15 v1 then a 15 v2 came out recently Not sure the difference.

They weigh a lot so not sure I would want more than 2. LOL

 

[TLS Guy]

Greetings,

I currently use dual Hsu VTF-3 MK5 subs in my primary setup. I've recently adjusted their positioning using REW and have them fairly well optimized for reasonably good frequency response and output given a variety of placement limitations. I'm very pleased with how they sound, however, during low frequency playback at loud volumes (sub-25Hz or so) I find that port chuffing can intrude. I currently run them in EQ1 mode w/ 1 port plugged for maximum extension. I've been toying with the idea of moving to subs with large enclosures and more port area to help with ULF performance and have narrowed my options down to the Monolith 13" and 15" subs.

Per James' review, the 13" Monolith seems to out-perform the 15" at virtually all frequencies (at least with the ports open). However, in looking at Erin's reviews of each of these subs, his results are quite different. Now, I understand that there are some differences in how each reviewer measures and captures the data, so it's understandable that the numbers between both may not align precisely. However, while Erin's measurements agree with James' in that they show the 15" Monolith gives up ULF output to the newer, more powerful 13", once it reaches into the midbass, the 15" handily bests the 13". This is in stark contrast to James' findings.

This is taken from Erin's review of the 13" Monolith:

View attachment 66311

Per this table, we can see better ULF output from the 13", but once each sub rounds 30Hz, the 15" is getting twice as loud (or better).

Compare this to James' data:

View attachment 66312

View attachment 66313

Based on Erin's data I'm likely going with the 15" to maintain the better midbass output. Based on James' data the 13" is an easy winner virtually everywhere. Why such a discrepancy?

To throw another wrench into the equation, I can currently purchase the 15" on sale for a dramatically lower cost than the 13". The difference in price in purchasing two is over $1400 in favor of the 15". I'm also open to the possibility that I am missing something simple.

Thanks in advance!

Your mistake is closing one port. When you do this the woofer is misaligned. There is only one optimal alignment in every speaker design.

If you close the ports the box is too big and misaligned. If you close one port then you push it towards those dreadful extended bass alignments.
You also pay the penalty that the vent air velocity is too high.

I know the subs you have. I used a pair of them in an installation I did and had my measuring equipment with me. I thought they were really good subs, but you need both ports open for them to work properly.

All this business of closing ports is nonsense and commercial outfits having to play the my F3 is lower than your F3 nonsense.

When I design speakers for myself or members here I do not get involved with that sort of idiocy. I design the best sounding sub I can, and don't allow them to be interfered with.

Just open both ports, and enjoy your subs.

 

[Verdinut]

Blocking one port lowers the tuning frequency of the box. That is often used to counteract some of the low frequency boominess which is caused by the room gain, when a subwoofer is placed in or close to a room corner.

Some manufacturers do provide port plug(s) and these can be used to help improve overall LF response somehow. In some situations if it works, why not?

 

[TLS Guy]

Blocking one port lowers the tuning frequency of the box. That is often used to counteract some of the low frequency boominess which is caused by the room gain, when a subwoofer is placed in or close to a room corner.

Some manufacturers do provide port plug(s) and these can be used to help improve overall LF response somehow.

They don't have any magic I don't. There is one optimal alignment for every driver in any given box, not two or three. So either one of those options is correct or all three wrong. For those subs both ports open is the optimal alignment. The laws of physics are the same for them and me. We all operate under the same rules.

 

[shadyJ]

Fair enough, thanks. It's definitely strange.

I would agree that based on your data, the 13" is the better sub overall, but the current sale pricing makes it prohibitive. For the price of two 13"s, three 15"s could be purchased. It doesn't look like Monoprice has had any significant sales on the 13" since it's been released. I'm sure they'll come around eventually.

The 13" was $1250 over the holiday season. And the 15" was on sale for $1100 recently. If you are patient, you can get good deals on these subs.

 

[shadyJ]

Think there was a monolith 15 v1 then a 15 v2 came out recently Not sure the difference.

They weigh a lot so not sure I would want more than 2. LOL

The differences between v1 and v2 are largely cosmetic. There were a few small changes elsewhere, but not enough to meaningfully impact performance.

 

[shadyJ]

They don't have any magic I don't. There is one optimal alignment for every driver in any given box, not two or three. So either one of those options is correct or all three wrong. For those subs both ports open is the optimal alignment. The laws of physics are the same for them and me. We all operate under the same rules.

I would say variable tuning is viable once you have all the dynamic range you want. But yes, you can run into port turbulence early by plugging a port, and in that case, run the sub with all ports open.

 

[TLS Guy]

I would say variable tuning is viable once you have all the dynamic range you want. But yes, you can run into port turbulence early by plugging a port, and in that case, run the sub with all ports open.

Shady, it is not that simple. This whole process makes no engineering or design sense. The fact is that an optimal box with optimal sound quality, a so called extended bass alignment and sealed boxes,, all have different box volumes, and not just by a small amount. So this whole concept is totally bogus and nonsense. It is just bad engineering. Again, I am jst so glad I don't have to shop for speakers. I do know how to do better than market the market has on offer.

 

[mj30250]

The 13" was $1250 over the holiday season. And the 15" was on sale for $1100 recently. If you are patient, you can get good deals on these subs.

Monoprice had the 15"s up on eBay this morning at a price of $2147 shipped to my door for two of them (including tax). That's pretty hard to pass up! A few hundred more for the 13"s wouldn't be unreasonable considering you get twice the amplifier power.

Anyway, in looking at the measurements on Monoprice's website, again with all ports open for each, the 15" seems to follow the 13" fairly closely and is stronger over most of the midbass frequencies, though the gap isn't as wide as Erin's data shows. Of course, for the 13" they are using your data, but I don't know what the source of their 15" data is. I dropped both into Excel to make it easier to compare:

Is it possible that the 15" you tested was output-limited/faulty in some way? In any case, both are clearly extremely robust subs that would likely serve my needs well.

They don't have any magic I don't. There is one optimal alignment for every driver in any given box, not two or three. So either one of those options is correct or all three wrong. For those subs both ports open is the optimal alignment. The laws of physics are the same for them and me. We all operate under the same rules.

I don't necessarily disagree, but the reality is that in opening both ports I'm giving up a significant amount of extension in the case of these subs - per their measurements. I'm not sure I'd be happy kicking the occasional chuffing to the curb if it takes the bulk of the infrasonics along with it. Of course, it won't hurt to try. Once the house is empty...

 

[TLS Guy]

Monoprice had the 15"s up on eBay this morning at a price of $2147 shipped to my door for two of them (including tax). That's pretty hard to pass up! A few hundred more for the 13"s wouldn't be unreasonable considering you get twice the amplifier power.

Anyway, in looking at the measurements on Monoprice's website, again with all ports open for each, the 15" seems to follow the 13" fairly closely and is stronger over most of the midbass frequencies, though the gap isn't as wide as Erin's data shows. Of course, for the 13" they are using your data, but I don't know what the source of their 15" data is. I dropped both into Excel to make it easier to compare:

View attachment 66328

Is it possible that the 15" you tested was output-limited/faulty in some way? In any case, both are clearly extremely robust subs that would likely serve my needs well.



I don't necessarily disagree, but the reality is that in opening both ports I'm giving up a significant amount of extension in the case of these subs - per their measurements. I'm not sure I'd be happy kicking the occasional chuffing to the curb if it takes the bulk of the infrasonics along with it. Of course, it won't hurt to try. Once the house is empty...

Everyone gets totally hung up on bass extension, to the exclusion of bass quality. It is NEVER the right trade off to sacrifice a bass quality for a few Hz of bass extension. People have their priorities reversed. Bass quality is priority ONE.

When visitors visit here the first thing they usually comment on is the bass quality. It is truly very, very close to live. Just while having this discussion I was committing to my DAW the last Minnesota Orchestra concert, which unusually included not one, but two concertos for double bass. The rig reproduced it in a completely believable and life like fashion. I hate to think what a lot, and probably most commercially available subs would have done to it.

In my designs I never trade bass quality for extension. Those members I have designed subs for have been very pleased with them.

 

[shadyJ]

Monoprice had the 15"s up on eBay this morning at a price of $2147 shipped to my door for two of them (including tax). That's pretty hard to pass up! A few hundred more for the 13"s wouldn't be unreasonable considering you get twice the amplifier power.

Anyway, in looking at the measurements on Monoprice's website, again with all ports open for each, the 15" seems to follow the 13" fairly closely and is stronger over most of the midbass frequencies, though the gap isn't as wide as Erin's data shows. Of course, for the 13" they are using your data, but I don't know what the source of their 15" data is. I dropped both into Excel to make it easier to compare:

View attachment 66328

Is it possible that the 15" you tested was output-limited/faulty in some way? In any case, both are clearly extremely robust subs that would likely serve my needs well.

You are using the wrong data set for the 15". Use the RMS column which is to the right of the column that you used (although they still labeled it "peak", a mistake). It is the same data, but just 3dB subtracted. You will see their measurements are close to mine.

Anyway, two good 15"s for $2150 is a hell of a deal.

 

[shadyJ]

Shady, it is not that simple. This whole process makes no engineering or design sense. The fact is that an optimal box with optimal sound quality, a so called extended bass alignment and sealed boxes,, all have different box volumes, and not just by a small amount. So this whole concept is totally bogus and nonsense. It is just bad engineering. Again, I am jst so glad I don't have to shop for speakers. I do know how to do better than market the market has on offer.

Agreed that it's not optimal, but just because it's not optimal doesn't mean there aren't worthwhile advantages in some situations. If you want the extension more than the headroom, then it is a worthwhile trade. As long as you aren't pushing the ports into turbulence, there is no harm.

 

[mj30250]

You are using the wrong data set for the 15". Use the RMS column which is to the right of the column that you used (although they still labeled it "peak", a mistake). It is the same data, but just 3dB subtracted. You will see their measurements are close to mine.

That makes more sense. I seem to recall Gene mentioning several years ago that all CEA-2010 numbers would be provided at peak output levels in reviews, not RMS, but I see now that your review mentions RMS. Monoprice looks like they've mislabeled several other subs as well (the 13" and 16" correctly show your RMS measurements). I've updated the chart to show Monoprice's published RMS numbers for the 15" V2.

Everyone gets totally hung up on bass extension, to the exclusion of bass quality. It is NEVER the right trade off to sacrifice a bass quality for a few Hz of bass extension. People have their priorities reversed. Bass quality is priority ONE.

With one port plugged, I do not feel as though I'm sacrificing any quality once the subs are a few Hz above the port tune. Sure, opening both ports provides some more midbass headroom, but with dual subs in a room that runs on the smaller side, I'm not pushing them anywhere close to capacity in that region, even at very loud volumes. It's more about what trade-offs you are willing to live with (as is the case in many aspects of audio). To get clean ULF extension without chuffing and loads of headroom at the same time, you either require massive drivers/cabinets, or a pile of sealed subs located and integrated well (the latter is not at all easy or cheap). Sure, if you have the room and the skills, DIYing massive boxes can get you there, but it's tough to find that combination in subs from commercial/ID manufacturers, especially at sane price points.

 

[Golfx]

I can not remember where I read this but perhaps it was Ricci’s who said all CEA/CTA 2010 numbers would have to be done by the same reviewer/method/equipment in order to have equivalent numbers. At this date, Shadyj’s are the gold standard for sub measurements.

 

[TLS Guy]

That makes more sense. I seem to recall Gene mentioning several years ago that all CEA-2010 numbers would be provided at peak output levels in reviews, not RMS, but I see now that your review mentions RMS. Monoprice looks like they've mislabeled several other subs as well (the 13" and 16" correctly show your RMS measurements). I've updated the chart to show Monoprice's published RMS numbers for the 15" V2.

View attachment 66329



With one port plugged, I do not feel as though I'm sacrificing any quality once the subs are a few Hz above the port tune. Sure, opening both ports provides some more midbass headroom, but with dual subs in a room that runs on the smaller side, I'm not pushing them anywhere close to capacity in that region, even at very loud volumes. It's more about what trade-offs you are willing to live with (as is the case in many aspects of audio). To get clean ULF extension without chuffing and loads of headroom at the same time, you either require massive drivers/cabinets, or a pile of sealed subs located and integrated well (the latter is not at all easy or cheap). Sure, if you have the room and the skills, DIYing massive boxes can get you there, but it's tough to find that combination in subs from commercial/ID manufacturers, especially at sane price points.

Actually the optimal box is always smaller than the extended bass box.

 

[mj30250]

Actually the optimal box is always smaller than the extended bass box.

Depending on how you are defining "optimum", that can be true. I suppose the best case sub scenario (at least in a typical domestic space that's configured for good audio reproduction) would be a large number of sealed subs properly positioned and equalized. This could provide deep extension and loads of headroom with zero port-chuffing. This also wouldn't necessarily require exceedingly large boxes, just a bunch of them.

In keeping with the subs under discussion, within the limits of its size and amplification, the Monolith 15" with 1 port plugged in extended mode looks pretty well optimized to me. See James' frequency response measurements:

That's almost as ruler-flat as a sub can get (especially at its price-point), and it also offers respectable extension to under 20Hz while keeping distortion largely below audible levels (per the measurements in an earlier post). The 13" is similarly flat in its 3-port THX mode. Of course, any ported sub can be made to chuff around and below its port-tune with enough volume pumped into it.

FWIW, I did some listening over lunch to the Hsu subs (I didn't have time to set up REW and take measurements; I plan to at some point), but I did play some pipe organ material that includes 16Hz notes with 1 port plugged and again with both ports open. With both ports open, chuffing was lessened of course, but the infrasonic rumbling of the organ's lowest notes was dramatically reduced as well.

In any case, I went ahead and ordered dual 15" Monoliths. The price was too good to pass up, and even though the 13" gets even louder down low, it looks like even with the 15"s I'd be picking up about 6dB at 16Hz and 4dB at 20Hz per sub compared to the Hsu with one port plugged. That's a pretty sizable improvement with the additional benefit of more open port area to help mitigate the audible turbulence. Thanks to everyone for their input.

 

[TLS Guy]

Depending on how you are defining "optimum", that can be true. I suppose the best case sub scenario (at least in a typical domestic space that's configured for good audio reproduction) would be a large number of sealed subs properly positioned and equalized. This could provide deep extension and loads of headroom with zero port-chuffing. This also wouldn't necessarily require exceedingly large boxes, just a bunch of them.

In keeping with the subs under discussion, within the limits of its size and amplification, the Monolith 15" with 1 port plugged in extended mode looks pretty well optimized to me. See James' frequency response measurements:

View attachment 66350

That's almost as ruler-flat as a sub can get (especially at its price-point), and it also offers respectable extension to under 20Hz while keeping distortion largely below audible levels (per the measurements in an earlier post). The 13" is similarly flat in its 3-port THX mode. Of course, any ported sub can be made to chuff around and below its port-tune with enough volume pumped into it.

FWIW, I did some listening over lunch to the Hsu subs (I didn't have time to set up REW and take measurements; I plan to at some point), but I did play some pipe organ material that includes 16Hz notes with 1 port plugged and again with both ports open. With both ports open, chuffing was lessened of course, but the infrasonic rumbling of the organ's lowest notes was dramatically lessened.

In any case, I went ahead and ordered dual 15" Monoliths. The price was too good to pass up, and even though the 13" gets even louder down low, it looks like I'd be picking up about 6dB at 16Hz and 4dB at 20Hz per sub compared to the Hsu with one port plugged. That's a pretty sizable improvement with the additional benefit of more open port area to help mitigate the audible turbulence. Thanks to everyone for their input.

The optimum box is they one that gives the flattest frequency response and optimises Q.

Sealed subs are not optimal designs. They save box volume, but have high f3 without a lot of Eq, and are highly inefficient. So they consume a lot of amp power and therefore are prone to higher distortion than other designs. I personally use aperiodically damped transmission lines which give deep effortless bass that is extremely natural and very high quality. I use an integrated approach, so that in effect you get a full range speaker. Tri-amped dual TL speaker with infinitely variable BSC for integration to room.

Axis FR and impulse response.

Axis and off axis responses out to 60 degrees black line.

Roll off at 15K is due to the measuring omnimic limitation.