CEA-2010 Rating LV12r?

[RythmikAudio]

Here are anwsers to other commonly asked questions:

1) Why is our sub more expensive?
A: As I explain above the our subs have higher resolution. We can hear the impact of components on sound quality. Our amplifiers are solidly built. Big toroid transformer and big power caps and therefore more expensive.

2) Other manufacturers have DSP and therefore is more accurate.
A: DSP is no substitute for servo. Servo is a feedback done by taking motional signal at where the action is originated. Where can DSP correct that with the same amount of accuracy? Using a microphone at your listening position? That will have too low signal to noise ratio. The highest signal noise ratio is correcting it at where the action takes place, not some 8ft 15 ft away. An analogy is Hubble telescope that required correction to the lens. How was that problem resolved? By implementing a DSP on the sensor signal? That will be proven to be ineffective because each pixel on the sensor receives optical information from everywhere on the lens summed together. Instead it is done by another correction lens in front of original lens. There is no way DSP can achieve what servo can achieve because they are designed for different objectives.

[RythmikAudio]

Brian, thank you for taking the time to give me such a detailed and informative response. It's nice to know that you truly care about sound quality and not just sales. This goes a LONG way in my book.

I think for most of us that have never engineered a subwoofer before, looking at plots and graphs is an easy way for us to decide on which subwoofer we want to buy (especially if we had never heard it before). It's good to know that plots and graphs may not always be as black and white as they seem, as one like myself that will not be buying a subwoofer again for a very, very long time will want to make the right decision for their situation.

As for my case, I wouldn't be able to afford dual VTF-15Hs or Dual FV15HPs. So, it really comes down to the PB-2000, F12, or LV12r. Taking price out of the equation between your 2 models, which would be the best for my situation: going with duals, 13x18x8ft room, tight transient response, want to be able have clean dynamic range up to 103 db at 20hz, and play linear down to 20hz. I know that I may not be able to get all that I ask for at that price point, but I really value dynamic range and linearity. If it can be tight and transient as well, that is a major plus. Knowing the things I value, what you would go for in that price point?

Again, thanks for your detailed and very informative response.

Thanks for the feedback. That is our objective in the future too -- providing more models at different price points so that customers will not have excuse not to buy from us. But it takes a bit of time and I have eaten too many words in the past for future models. So I don't want to say anything other than we are actively working on it. But for now, LV12R is our recommendation for those with tight budget. We have been selling a lot of LV12R. The feedback on sound quality of these subs is very consistent. If you come to our website, you will read a lot of feedback. Some of them do keep the feedback simple and short while others are detailed and elaborated. Check to see if those points they made are your high priority. F12 is sealed (and therefore more compact) and therefore tighter sound. But you will sacrifice a bit on maximum SP, but you get better bass extension. BTW, two LV12R can achieve 103db at 20hz without a problem.

[Johnny_Mac_III]

Thanks for the feedback. That is our objective in the future too -- providing more models at different price points so that customers will not have excuse not to buy from us. But it takes a bit of time and I have eaten too many words in the past. So I don't want to say anything other than we are actively working on it. But for now, LV12R is our recommendation for those with tight budget. We have been selling a lot of LV12R. The feedback on sound quality of these subs is very consistent. If you come to our website, you will read a lot of feedback. Some of them do keep the feedback simple and short while others are detailed and elaborated. Check to see if those points they made are your high priority. F12 is sealed (and therefore more compact) and therefore tighter sound. But you will sacrifice a bit on maximum SP, but you get better bass extension. BTW, two LV12R can achieve 103db at 20hz without a problem.

Thanks again for the quick response, Brian. I have a question about the high Q setting on the LV12r. Will that filter everything out at 24 hz or is that just where the rolloff begins? Could room gain extend the bass even further if everything isn't filtered out? What is the difference between the high q vs low q in sound quality?

[davef]

If I may...

I am extremely familiar with both HSU and SVS subs, and while yes, they offer excellent bang for buck performance, neither compare well with any of the Rythmik subwoofers with regard to accuracy and transient response. For Ascend speakers, especially towers and Sierra-2, I strongly recommend spending the extra $$$ to get an appropriate Rythmik. Sure, we make a few bucks (a lot less than you would guess), but that has nothing to do with my recommendation.

Keep in mind that I started engineering subwoofers more than a decade before there even was an SVS - and the only reason Ascend does not have a line of subwoofers is that after fully evaluating Brian's work -- I realized that these are exactly the same performance goals I have -- and even with my experience and vast industry resources, we could not do better.

[Johnny_Mac_III]

If I may...

I am extremely familiar with both HSU and SVS subs, and while yes, they offer excellent bang for buck performance, neither compare well with any of the Rythmik subwoofers with regard to accuracy and transient response. For Ascend speakers, especially towers and Sierra-2, I strongly recommend spending the extra $$$ to get an appropriate Rythmik. Sure, we make a few bucks (a lot less than you would guess), but that has nothing to do with my recommendation.

Keep in mind that I started engineering subwoofers more than a decade before there even was an SVS - and the only reason Ascend does not have a line of subwoofers is that after fully evaluating Brian's work -- I realized that these are exactly the same performance goals I have -- and even with my experience and vast industry resources, we could not do better.

Thanks Dave. Which subwoofer do you feel would be appropriate for the CBM-170s?

[N Boros]

Now when it comes to servo, most people will think it is to reduce distortion simply because that concept is simple to understand. But it goes beyond that. One of the area that servo improves is the linear scalability. Databass site publishes curves from 90db all the way to 110db, it serves a purpose. It wants to see how a sub scales with different input level. So if we have a particular 90db FR curve, we want to see in ideal case that when input increases by 5db, the output will simply have 5db added to 90db FR curve. Same thing if the input increases by 10db, 15db, ..etc. Now the best way to check this linear scalability is we can just use 90db as reference, deduct (5db + 90db curve) from the 95db curve, and deduct (10db + 90db curve) from the 100db curve,...etc and all these plots form a so-called "output compression magnitude plot". If a system is perfectly linearly scalable, all these normalized curves will be on top of one another and be 0db. But in reality, the measurement will inevitably pick up noise in one or two measurements. That can cause it to have deviation on one or two curves. It is important to check the tend. Our FV15HP shows the best output compression curve that any sub can see (even better than Velodyne DD-18). The plot of 1 port mode shows the curves are in an extreme tight range above 30hz. The entire band of curves do move up and down because the noise in the 90db measurement curve has moves every other curves up and down at the same time.

So why is this important? Music is dynamic and constanly changing its signal strength. The ability to maintain linearity throughout the entire signal strength range is the first key to high fidelity. In non-servo, the problem is so serious that engineers just cross their fingers and hope for the best. On the other hand, servo completely solves this problem. Moreover, one reason nonservo subs have these problems is because the voice coil temperature can change after we put in that 100W to 600W power to the voice coil. When the temperature goes up, so is the voice coil resistance and that chokes the amount of current going to the driver even when the amplifier output stays the same. Unortunately voice coil temperature does not cool down instantaneously. That becomes a memory effect. We all see how a pressure on a memory foam will leave an imprint that takes time to recover. Same thing is heating up the voice coil. So why is this important? Same linear scalability needs to apply to time domain as well(vs in the domain of the signal strength as discussed above). If we measure a 90db curve A at time moment 0, we expect the same 90db curve to be repeatable at any other time. This seems to be very easy. But later we will see how much better our servo subs perform. The way to test this is Josh will publish two 90db curves in the "long term output compression" plot. The first 90db curve is what he normally runs. The second 90db curve (labelled as 90db REPEAT) is done as soon as he finishes the highest SPL sweep (after the voice coil heats up). Our sub is the only sub that has those two curves almost identical. It is not because of luck. It is because of servo operation. The problem of memory effect is that if we have notes A, B, C, and D. The sequence of these notes can change the strength of each because the power burnt by each note will affect the output of subsequent notes up to some time. It is a type of distortion. Our subs will sound more realistic because it is linear scalable on both signal and on time. The sequence of notes does not affect the playback strength of each note. You can play ABCD or DCBA and each A will have the same strength. That is the coherance we want.

I read this a month ago and thought it was a very interesting point that is subtle to see from the long term output compression plots. Like Brian said, many of the manufactured subs don't have linear scalability, like the Rythmik subs do. The subs may just be designed to put out as much as possible at any frequency. Some of the more respected companies, do make sure to keep distortion in check when doing this, but still don't have the linear scalability as the Rythmik. Also, going through the list of 10 to 15 subs from companies measured on DataBass, Rythmik is the only sub to have this linear scalability, with its amount of output , flat frequency response, extension, distortion and transient response at its price point. I was convinced before that I could save some money to get a sub with about the same output, extension and flat frequency response as the FV15HP, but I finally see that there are a lot of other factors I would be giving up which will likely negatively effect the sound quality. Even just focusing on the output and flat frequency response, the FV15HP is a good value. But when you factor in all of the other areas that it does very well within (and even outside) it's price class, its value is even better. I'm pretty sure I will be going with a couple of FV15HPs when I save up the money.

[Johnny_Mac_III]

I appreciate all of the responses. After talking with Enrico, I decided to go with 2 F12s. Again thanks for the help.

**Edit** Unfortunately, ordering 2 f12s was a no-go with my wife. haha I ended up ordering a LV12r. I'm sure I will still be happy as it has gotten very good reviews.

[Johnny_Mac_III]

So, after having my LV12r for over a month now, I have to say that I am very satisfied! The first thing that stood out to me was how well it blended with my 340 se fronts. It does what I was looking for my sub to do ...it makes my speakers sound full range. It is also VERY musical and accurate. I just want to thank Brian, Dave, and everyone else that contributed for taking the time to answer my questions in this thread.