PSA S1500 vs. Rythmik F15HP

[shadyJ]

You are a smart guy, and your speculations have reasonable thought behind them; however, at the end of the day they are still speculations.
Somewhere I read a review where the reviewer discussed the servo system with Brian Ding and made the comment that the servo allowed a lesser driver to compete with better drivers. Unfortunately, I cannot find it to be able to better appraise the source.
The fact that they are very competitive in the ID sub market means they are somehow getting performance to offset the cost of adding the servo.

I would also point out that you chose the FV15HP to make the case against PSA, which is an amazing value and pretty well beats anything Hsu, SVS, or PSA have to offer.

First of all, we only have conjecture that a servo system can offer improvements over a conventional bass speaker system to begin with. I have seen no evidence that it does, but some of the theory doesn't sound unreasonable, so I am not inclined to rule out that it could, although I do not believe it is as much as these manufacturers claim. Rythmik in particular does make good subwoofers, but how much do we attribute that to the servo system and how much is it due to just good design otherwise? Just look at this beefy DS1510 driver, it looks like it would hardly need the assistance of a servo system to offer good performance:

As for the FV15HP beating anything that SVS, Hsu, or PSA has to offer, I disagree on all counts. For SVS, it is not on the level of the PB16-Ultra, although there are some aspects in which I think it would outperform the PB16-Ultra. For the most part however, the PB16-Ultra will have a major advantage, but then again, it is a lot more expensive. For Hsu, I think it will have some advantages over the VTF15h mk2, but the VTF15h mk2 may have some advantages of its own. I would guess that the FV15HP has a tad more performance overall, but it would not comprehensively outperform the VTF15h mk2. Hsu's 15" driver is a great performer itself. I don't know how Hsu can afford to put that driver in such low cost subs. For PSA, I am pretty sure that PSA's new sub with four 18"s and a 4 kW amp will be able to outperform the FV15HP by any metric. This is not to offer PSA any praise, since their sub costs 3x as much and weighs 3x as much. It should be able to outperform the FV15HP by sheer brute force.

And as for choosing the FV15HP as an example, I am forced to, because there are no other third-party measurements of any other Rythmik products, except for an old DIY rig at home theater shack. Rythmik has been coasting on the impressive measurements of the FV15HP for a long time now. It's not easy for me to get enthusiastic about products whose performance will never be proven. I am sure their newer stuff isn't bad, but it is not on my radar as much, because I don't think I will ever see any real data on them.

 

[Roen]

First of all, we only have conjecture that a servo system can offer improvements over a conventional bass speaker system to begin with. I have seen no evidence that it does, but some of the theory doesn't sound unreasonable, so I am not inclined to rule out that it could, although I do not believe it is as much as these manufacturers claim. Rythmik in particular does make good subwoofers, but how much do we attribute that to the servo system and how much is it due to just good design otherwise? Just look at this beefy DS1510 driver, it looks like it would hardly need the assistance of a servo system to offer good performance:

As for the FV15HP beating anything that SVS, Hsu, or PSA has to offer, I disagree on all counts. For SVS, it is not on the level of the PB16-Ultra, although there are some aspects in which I think it would outperform the PB16-Ultra. For the most part however, the PB16-Ultra will have a major advantage, but then again, it is a lot more expensive. For Hsu, I think it will have some advantages over the VTF15h mk2, but the VTF15h mk2 may have some advantages of its own. I would guess that the FV15HP has a tad more performance overall, but it would not comprehensively outperform the VTF15h mk2. Hsu's 15" driver is a great performer itself. I don't know how Hsu can afford to put that driver in such low cost subs. For PSA, I am pretty sure that PSA's new sub with four 18"s and a 4 kW amp will be able to outperform the FV15HP by any metric. This is not to offer PSA any praise, since their sub costs 3x as much and weighs 3x as much. It should be able to outperform the FV15HP by sheer brute force.

And as for choosing the FV15HP as an example, I am forced to, because there are no other third-party measurements of any other Rythmik products, except for an old DIY rig at home theater shack. Rythmik has been coasting on the impressive measurements of the FV15HP for a long time now. It's not easy for me to get enthusiastic about products whose performance will never be proven. I am sure their newer stuff isn't bad, but it is not on my radar as much, because I don't think I will ever see any real data on them.

How long has the FV15HP been out? Same time as the F15HP?

 

[speakerman39]

Roen, the Hsu ULS 15 MK2 sub is also very good. Especially, given its price. The 15" driver is also very good. However, if you want to spend more and move up to the S1500 that is good too. Honestly I also wanted the Rythmiks, but just could not afford them. But you would be hard pressed going wrong with any of the three mentioned inmho. Duals would be splendid either way! Best wishes in making your decision!


Cheers,

Phil

 

[Roen]

I have the S1500 already, but I'm very much considering returning it for an F15HP-SE for the Direct Servo and to match my other Piano Black speakers.

For 1500 ft^3, one is already overkill, let alone two!

 

[speakerman39]

I have the S1500 already, but I'm very much considering returning it for an F15HP-SE for the Direct Servo and to match my other Piano Black speakers.

For 1500 ft^3, one is already overkill, let alone two!

I see. Did not know that you had the S1500 already. My room is only 1,440 ft.^3 and I had dual S1500's. They sounded fantastic! Never really got to rock out too much b/c I reside in an apartment. To make matters worse, the apartment manger lives directly below me.....LOL!!! But, I understand wanting the Rythmik. I did as well, but too rich for my blood. Best wishes!


Cheers,

Phil

 

[Roen]

I see. Did not know that you had the S1500 already. My room is only 1,440 ft.^3 and I had dual S1500's. They sounded fantastic! Never really got to rock out too much b/c I reside in an apartment. To make matters worse, the apartment manger lives directly below me.....LOL!!! But, I understand wanting the Rythmik. I did as well, but too rich for my blood. Best wishes!


Cheers,

Phil

Wow....dual in a room smaller than mine.

You must have a schedule when your apartment manager vacates the premises........when you can really turn out the sub.

Actually, today, I waited until 10 am before I did a sub killer test: Edge of Tomorrow opening scene before credits.

My sub gain was set to 2 o'clock and -3 db on the AVR. For reference, YPAO has me at -9 when the sub gain is at 10:30 - 11.

 

[speakerman39]

Wow....dual in a room smaller than mine.

You must have a schedule when your apartment manager vacates the premises........when you can really turn out the sub.

Actually, today, I waited until 10 am before I did a sub killer test: Edge of Tomorrow opening scene before credits.

My sub gain was set to 2 o'clock and -3 db on the AVR. For reference, YPAO has me at -9 when the sub gain is at 10:30 - 11.

Yeah, I had duals. But, never got to really open them up much. The apartment manager is a homebody. As such, she seldom goes anywhere. On the weekends, she leaves every once in a while and I can rock out some. I am a music guy not HT. But, both the ULS 15 MK2 and/or the S1500 were good at both. Lots of power!


Cheers,

Phil

 

[KEW]

As for the FV15HP beating anything that SVS, Hsu, or PSA has to offer, I disagree on all counts. For SVS, it is not on the level of the PB16-Ultra, although there are some aspects in which I think it would outperform the PB16-Ultra. For the most part however, the PB16-Ultra will have a major advantage, but then again, it is a lot more expensive. For Hsu, I think it will have some advantages over the VTF15h mk2, but the VTF15h mk2 may have some advantages of its own. I would guess that the FV15HP has a tad more performance overall, but it would not comprehensively outperform the VTF15h mk2. Hsu's 15" driver is a great performer itself. I don't know how Hsu can afford to put that driver in such low cost subs. For PSA, I am pretty sure that PSA's new sub with four 18"s and a 4 kW amp will be able to outperform the FV15HP by any metric. This is not to offer PSA any praise, since their sub costs 3x as much and weighs 3x as much. It should be able to outperform the FV15HP by sheer brute force.

And as for choosing the FV15HP as an example, I am forced to, because there are no other third-party measurements of any other Rythmik products, except for an old DIY rig at home theater shack. Rythmik has been coasting on the impressive measurements of the FV15HP for a long time now. It's not easy for me to get enthusiastic about products whose performance will never be proven. I am sure their newer stuff isn't bad, but it is not on my radar as much, because I don't think I will ever see any real data on them.

Seriously, I said value!
I said:

I would also point out that you chose the FV15HP to make the case against PSA, which is an amazing value and pretty well beats anything Hsu, SVS, or PSA have to offer.

So you are sure the Rythmik has a better driver, and this is based on the servo not doing much of anything, and Rythmik's claims being false, but you have no evidence of that.
This is my point! You are being rather loose with your use of sure.

 

[shadyJ]

Seriously, I said value!
I said:

Value is subjective, unless you give it some quantifiable metric. In terms of performance, you might be able to say something like (clean SPL)/$ and also factoring in bass extension in both high frequency extension and low frequency extension. We should also factor in linearity, both baseline linearity and linearity in headroom. And all of these factors are application dependent, so there are situations where situations where deep bass extension is more important than mid bass output, and vice-versa. The Rythmik is a very good value, no doubt, but I wouldn't say it is the absolute best. It depends on what aspect of performance you are looking for. And most people don't equate value to raw performance anyway, as well they shouldn't.

So you are sure the Rythmik has a better driver, and this is based on the servo not doing much of anything, and Rythmik's claims being false, but you have no evidence of that.
This is my point! You are being rather loose with your use of sure.

I am not certain how much of Rythmik's performance is due to its conventional design choices or how much can be attributed to the servo technology. I would say until Rythmik demonstrates the difference in a comparative test, we should assume it does nothing. Now I don't really believe it is doing nothing, but the proper objective position to take is to assume it does nothing until proven otherwise. It is Rythmik's obligation to prove their own claims, and they have never done that, as far as I know. They have proven that they produce a high-performing subwoofer for the money. Personally I would say that is all that matters. I don't care whether that performance was achieved through conventional design or servo control; the results are more important than the methods.

 

[Irvrobinson]

I am not certain how much of Rythmik's performance is due to its conventional design choices or how much can be attributed to the servo technology. I would say until Rythmik demonstrates the difference in a comparative test, we should assume it does nothing. Now I don't really believe it is doing nothing, but the proper objective position to take is to assume it does nothing until proven otherwise. It is Rythmik's obligation to prove their own claims, and they have never done that, as far as I know. They have proven that they produce a high-performing subwoofer for the money. Personally I would say that is all that matters. I don't care whether that performance was achieved through conventional design or servo control; the results are more important than the methods.

When Josh Ricci reviewed the Velodyne DD18 Plus he measured the difference in output between the min and max of the servo feedback setting (which happens to be adjustable in the Velodyne). There was a non-trivial measurable difference, but the Funk Audio 18.0 subwoofer, a similarly sealed non-servo design, achieved equal or better performance than the Velodyne at 20Hz and above. I think there's evidence that servo technology can improve any given sealed sub design, but I think there's also evidence that other factors make servo technology mostly irrelevant. It's not dumb like, say, McIntosh autoformers on solid state amps, but servo technology would not be a purchase factor for me in the future.

 

[shadyJ]

When Josh Ricci reviewed the Velodyne DD18 Plus he measured the difference in output between the min and max of the servo feedback setting (which happens to be adjustable in the Velodyne). There was a non-trivial measurable difference, but the Funk Audio 18.0 subwoofer, a similarly sealed non-servo design, achieved equal or better performance than the Velodyne at 20Hz and above. I think there's evidence that servo technology can improve any given sealed sub design, but I think there's also evidence that other factors make servo technology mostly irrelevant. It's not dumb like, say, McIntosh autoformers on solid state amps, but servo technology would not be a purchase factor for me in the future.

That is a really good catch Irv, it has been so long since that review I had forgotten all about it. The best evidence for the difference of the servo system is in the THD measurements of the compression sweeps. Looking at that closely right now, there is a lot of interesting little differences. The key thing to look at is the reduction in the third harmonic below the resonant frequency of the driver. Strangely it didn't seem to make a difference in 2nd order harmonics, which is where I though it would have the greatest effect.

The only other area that servo makes a big difference is it extends the high frequency response- although not in burst testing. Burst testing shows you the mechanical limits of the driver, and here is the best argument against the effects of servo. One might point to the difference at 10 Hz and 12.5 Hz, except those are such long test tones that they hardly qualify as 'burst' testing. A CEA-2010 test burst at 10 Hz and 12.5 Hz lasts for over half a second. This is why very often when you compare the long term sweeps against the CEA-2010 tests, the deep frequencies of the long term output can match or even exceed the burst output, but burst output is always more at upper frequencies. Of course, upper frequency stuff will be more amplifier limited than low frequency stuff.

I think the difference in reduction in the third harmonic below 30 Hz can not be ignored, since the driver is producing the same amount of output, but the similarities in burst testing is hard to ignore as well. The extra high frequency extension is not so easy to explain. Servo can not physically make a driver more electromechanically sensitive than it already is. I can only guess that the way the servo system applies the amplification current is more efficient at the top end. But there may be other factors at play that don't make this a good comparison, like filters of other types of processing.

 

[KEW]

I am not certain how much of Rythmik's performance is due to its conventional design choices or how much can be attributed to the servo technology.

Exactly my point! You cannot say you are sure without having certainty (and you state you do not)!
If you said you believe, that would be fine, but as a reviewer here with a great deal of experience, many of the readers would look to you as an expert, likely to have definitive knowledge. Not someone who is stating his opinion as being fact!
I would expect you to choose your words a little more carefully and only reach absolute conclusions when you have the info to properly reach them!

Now I don't really believe it is doing nothing, but the proper objective position to take is to assume it does nothing until proven otherwise.

No! The proper objective position is to not assume anything unless you make clear exactly what assumptions were made for the analysis! And then you do not conclude by saying that you are sure of the result without qualification referring to the assumptions made!

As part of the AH community, I like to believe when the staff is providing decisive statements they are based on fact rather than speculation. You have a great deal of knowledge/experience and being a reviewer here puts you in a position of authority. Please don't be sloppy!

 

[Pogre]

I see. Did not know that you had the S1500 already. My room is only 1,440 ft.^3 and I had dual S1500's. They sounded fantastic! Never really got to rock out too much b/c I reside in an apartment. To make matters worse, the apartment manger lives directly below me.....LOL!!! But, I understand wanting the Rythmik. I did as well, but too rich for my blood. Best wishes!


Cheers,

Phil

You bought two 15" subs for a 1440'^3 apartment? Wow Phil. I'll bet that didn't last too long! lol

 

[Irvrobinson]

That is a really good catch Irv, it has been so long since that review I had forgotten all about it. The best evidence for the difference of the servo system is in the THD measurements of the compression sweeps. Looking at that closely right now, there is a lot of interesting little differences. The key thing to look at is the reduction in the third harmonic below the resonant frequency of the driver. Strangely it didn't seem to make a difference in 2nd order harmonics, which is where I though it would have the greatest effect.

The only other area that servo makes a big difference is it extends the high frequency response- although not in burst testing. Burst testing shows you the mechanical limits of the driver, and here is the best argument against the effects of servo. One might point to the difference at 10 Hz and 12.5 Hz, except those are such long test tones that they hardly qualify as 'burst' testing. A CEA-2010 test burst at 10 Hz and 12.5 Hz lasts for over half a second. This is why very often when you compare the long term sweeps against the CEA-2010 tests, the deep frequencies of the long term output can match or even exceed the burst output, but burst output is always more at upper frequencies. Of course, upper frequency stuff will be more amplifier limited than low frequency stuff.

I think the difference in reduction in the third harmonic below 30 Hz can not be ignored, since the driver is producing the same amount of output, but the similarities in burst testing is hard to ignore as well. The extra high frequency extension is not so easy to explain. Servo can not physically make a driver more electromechanically sensitive than it already is. I can only guess that the way the servo system applies the amplification current is more efficient at the top end. But there may be other factors at play that don't make this a good comparison, like filters of other types of processing.

It was easier for me to remember, since I'm a DD18 Plus owner. That was also perhaps the best subwoofer review I've ever read, as judged by the completeness of the measurements and the expert interpretation of what they mean, making it even more memorable. (The associated forum thread is also fascinating. In that thread Gene called me a keyboard commando with a post count lower than my IQ. It still gives me a chuckle when I think about it.)

Since purchasing the Velodyne and subsequently measuring several peoples' systems, and learning much more about subwoofer integration over time, I've come to the conclusion that most people over-estimate their subwoofer power and capability needs. Yes, if you have a huge home theater room and you like to listen to action movies at unrealistic levels as if they were surrealistic cartoons (thank you for that analogy), you'll need several big subs to meet your objectives. But if you just want bass that gives you "no sense of loss" on any music and even action movies, and not bloated, outsized over-emphasized bass, most peoples' subwoofer needs are less than they think they are. Low distortion is more important than peak output capability, IMO. The last person's system I measured had two SVS SB13-Ultras in a room I'd estimate at 23x28x10 or larger, and when I adjusted the system for approximately +3db @ 30Hz and -6db @ 10KHz, which I think often produces a natural balance for acoustic music, he exclaimed, "That sounds good, but I can hardly hear the subs!" I'm confident that after I left he put the settings back to his original ones.

 

[Roen]

It was easier for me to remember, since I'm a DD18 Plus owner. That was also perhaps the best subwoofer review I've ever read, as judged by the completeness of the measurements and the expert interpretation of what they mean, making it even more memorable. (The associated forum thread is also fascinating. In that thread Gene called me a keyboard commando with a post count lower than my IQ. It still gives me a chuckle when I think about it.)

Since purchasing the Velodyne and subsequently measuring several peoples' systems, and learning much more about subwoofer integration over time, I've come to the conclusion that most people over-estimate their subwoofer power and capability needs. Yes, if you have a huge home theater room and you like to listen to action movies at unrealistic levels as if they were surrealistic cartoons (thank you for that analogy), you'll need several big subs to meet your objectives. But if you just want bass that gives you "no sense of loss" on any music and even action movies, and not bloated, outsized over-emphasized bass, most peoples' subwoofer needs are less than they think they are. Low distortion is more important than peak output capability, IMO. The last person's system I measured had two SVS SB13-Ultras in a room I'd estimate at 23x28x10 or larger, and when I adjusted the system for approximately +3db @ 30Hz and -6db @ 10KHz, which I think often produces a natural balance for acoustic music, he exclaimed, "That sounds good, but I can hardly hear the subs!" I'm confident that after I left he put the settings back to his original ones.

To each their own, I don't think acoustic settings match modern pop / rap / r&b bass requirements.

But to each their own.


Sent from my iPad using Tapatalk

 

[speakerman39]

You bought two 15" subs for a 1440'^3 apartment? Wow Phil. I'll bet that didn't last too long! lol

At first I originally wanted dual 15" Rythmik subs. At about the same time, I was came across a deal on a B-stock Hsu ULS 15 MK2 sub and ordered it. It was not long after that I decided to order a PSA S1500 as well. My goal was to have more even bass and not so much for slam. Of the two, I preferred the S1500 so I ordered another and sold the ULS 15 MK2.

Looking back, I do think that I would have been just as happy w/dual ULS 15 MK2's. The Rythmiks were just more than I could afford. Music is my concern so I crave tight, punchy, well articulated bass that offers distinction in the transients. The old "hit on a dime" AND "stop on a dime" was very important to me. Hence, both the ULS 15 MK2 and /or the S1500 gave me just that in my room.

Being in such a small room w/dual 15" sealed subs created some issues with room gain. But, I was able to get things dialed in (tamed) very well to minimize such issues. They both were great with music and gave me plenty of slam for HT. But, never really got to push them to their limits. At times though, I did get to rock out some. No need to get evicted.


Cheers,

Phil

 

[shadyJ]

Exactly my point! You cannot say you are sure without having certainty (and you state you do not)!
If you said you believe, that would be fine, but as a reviewer here with a great deal of experience, many of the readers would look to you as an expert, likely to have definitive knowledge. Not someone who is stating his opinion as being fact!
I would expect you to choose your words a little more carefully and only reach absolute conclusions when you have the info to properly reach them!


No! The proper objective position is to not assume anything unless you make clear exactly what assumptions were made for the analysis! And then you do not conclude by saying that you are sure of the result without qualification referring to the assumptions made!

As part of the AH community, I like to believe when the staff is providing decisive statements they are based on fact rather than speculation. You have a great deal of knowledge/experience and being a reviewer here puts you in a position of authority. Please don't be sloppy!

What statements of mine do you have trouble with? I am not even sure what you are disputing. As for Rythmik, the burden of proof lies with them to demonstrate the difference their technology makes. The audio business is so rife with unproven claims of the superiority of technology X or Z that I would advise doubt on any and all claims until evidence is provided. Rythmik is no exception- they have only had one product tested and that was 6 years ago.

 

[Roen]

What statements of mine do you have trouble with? I am not even sure what you are disputing. As for Rythmik, the burden of proof lies with them to demonstrate the difference their technology makes. The audio business is so rife with unproven claims of the superiority of technology X or Z that I would advise doubt on any and all claims until evidence is provided. Rythmik is no exception- they have only had one product tested and that was 6 years ago.

Regardless of proof/absence of proof, the proper objective position is no position and no speculation.


Sent from my iPad using Tapatalk

 

[KEW]

What statements of mine do you have trouble with?

This:

Between these subs, I would go for the Rythmik, notwithstanding the servo technology (which I think might only make an audible difference at the extremes of excursion), I am sure they are using a higher-quality driver.

My reply was:

One feature of the servo design is it does not need as good of a driver nor as powerful of an amp to get equivalent performance.
What makes you sure that the Rythmik driver is higher-quality?
Given your acrimonious history with PSA, you should back that statement up with specifics.

From there, you have made a case based on assumptions, but you never provided factual info to explain how you could be sure!

PS In every subsequent response of mine, I re-emphasized that your saying you were "sure" was my concern. How did you lose track of what statement I was referring to? Look back and see for yourself!

 

[shadyJ]

This:

My reply was:


From there, you have made a case based on assumptions, but you never provided factual info to explain how you could be sure!

Lol, OK that one. OK, I am not absolutely 100 percent sure that Rythmik is using a higher performing driver, but I will seriously bet anyone a large sum of money that is the case. I am not certain that Rythmik is using a higher-performing driver in the same way I am not certain that there are no unicorns and elves living on Neptune. At data-bass.com, look at the THD sweeps of the FV15HP vs the XV30se, specifically the third harmonic. These sweeps tell you when the driver is getting stressed. Rythmik's single DS1510 can keep up pretty well with both of PSA's LAB15 variants. I have a hard time believing that these drivers are somehow equal, and that the servo technology can make up that difference. It's just not plausible. But hey, I could be wrong- about the unicorns and elves on Neptune!