Wishing a warm welcome to Rythmik Audio

[Blake1214]

Weird, I always thought it wouldn't make a difference, most bass being omnidirectional and all. You could try getting a subdude to place underneath.

Thought about that too. But keep in mind, my condo is a miniscule 927 sq ft. If you've seen these subs in person, you'll know adding another few inches to their already water tank dimension will truly warf my living area.

Besides, that won't give me an excuse to upgrade my HT.

Dave, besides the F15 in PB finish, any plans on a package discount for returning customers or people who buys more than one sub?

[azanon]

I'm glad to see that this time, a choice was made to go with a sub that focuses primarily on sound quality. I hope this is the focal point of comments about this sub at 3rd party forums like AVS.

[RythmikAudio]

Thanks for the introduction from David. Direct servo subwoofers may be relatively new for most members here. So please feel free to ask questions. I should be able to visit to forum once to twice a day. If you don't get reply in a timely manner, feel free to send me PM to remind me. Secondly, my writing style can be very dry and too technical. If that is the case, please feel free to remind me.

Two questions that I have heard so far:
1) F12 is same as F12SE except finish. Currently we have very limited inventory for F12.
2) F15 piano finish is still under evaluation. So I cannot give definitive answer in terms of which driver/amplifier will be used.

DirectServo subwoofers have been in the market for quite a few years, although in a slightly different form. The design objective has always been musicality first and within that boundary try to get the highest possible SPL. With that being said, for majority of customers I am pretty confident that the SPL output is sufficient for HT usage. Also, we have a very flexible extension filter setting that allow us the trade off SPL with extension. For those who would like to get higher SPL, please set that to 28hz/low damping, or 20hz/low damping. For the most musical sound, 14hz high damping is what most will use.

[clarke68]

Welcome to the forum, Brian!

It'll be great to have you around...I always appreciate a chance to pick the brain of people who know how to get good sound. Question for you about the following quote:

The design objective has always been musicality first and within that boundary try to get the highest possible SPL. For the most musical sound, 14hz high damping is what most will use.

What is "musicality" from an engineering perspective? How do you determine when a subwoofer is "musical" or not?

This term gets used quite a bit in the audio press without a clear definition. I use it often myself to describe sound that is realistic & emotionally engaging. I know it when I hear it, but I don't necessarily know when I don't hear it (hopefully that makes sense). Still, I have no idea how it could be produced (or not) or measured using the tools you have as an engineer, or what would determine the "boundaries" of musicality that you mention.

[davef]

Welcome to the forum, Brian!

It'll be great to have you around...I always appreciate a chance to pick the brain of people who know how to get good sound. Question for you about the following quote:

What is "musicality" from an engineering perspective? How do you determine when a subwoofer is "musical" or not?

This term gets used quite a bit in the audio press without a clear definition. I use it often myself to describe sound that is realistic & emotionally engaging. I know it when I hear it, but I don't necessarily know when I don't hear it (hopefully that makes sense). Still, I have no idea how it could be produced (or not) or measured using the tools you have as an engineer, or what would determine the "boundaries" of musicality that you mention.

Great question Clarke and I too look forward to Brian's response.

For me, I define "musicality" when referring to a subwoofer as the unit's ability to present tonal accuracy and, more importantly, to be able to reproduce and clearly distinguish multiple tones at the same time. For example, reproduction of a bass guitar note at the same time as a pipe organ. This is more complicated than it might seem due to high-excursion demands where the woofer loses motor force and control. Imagine a woofer reproducing a 20Hz tone with massive excursion demands while also having to reproduce a 60Hz tone at the same time. The 20Hz tone can have a tremendous negative impact on that more subtle 60Hz tone, especially at high output levels, where the 60Hz tone will suffer a loss of detail or be “glossed over" completely. Often referred to as "one note bass".

One note bass is often quite adequate for home theater because most people are more concerned with impact and room rumbling deep bass and they don’t care about subtle details (nothing really subtle about a train wreck ) However, this is not acceptable for music listening, IMO, where much of the music detail can be lost. It is in this area where Direct Servo excels, the amplifier is constantly monitoring both the velocity and excursion of the woofer and errors are instantly corrected at the speed of light, which is faster than sound so they are corrected before you hear them.

Imagine shooting a high-power rifle at two distinct targets and you must fire each shot within a millisecond of each other. The very best rifleman might be able to hit that first target, but the kick of the first shot will prevent any chance of that second shot reaching the target. What if that rifleman had to fire 5 or 6 shots within 1 or 2 milliseconds? What a mess. Now imagine if the flight of each of those bullets was controlled by a high speed computer such that they would be directed to the target regardless of any external variables or operator error. That is the difference servo control represents.

The woofer is precisely controlled and every note is reproduced cleanly without a loss of detail. The result is what I define as "musicality"

[RythmikAudio]

What is "musicality" from an engineering perspective? How do you determine when a subwoofer is "musical" or not?

This term gets used quite a bit in the audio press without a clear definition. I use it often myself to describe sound that is realistic & emotionally engaging. I know it when I hear it, but I don't necessarily know when I don't hear it (hopefully that makes sense). Still, I have no idea how it could be produced (or not) or measured using the tools you have as an engineer, or what would determine the "boundaries" of musicality that you mention.

My 5th grade son has been learning piano for about 7 years now. I constantly comparing between how he and his teacher playing the same piece of music and try to communicate with him what he should pay attention to when he practices at home. This analysis mode, plus other experiences listening to stereo systems makes me think more about musicality. For me, musicality is the correct combination of contrast (some call it dynamics), articulation, and pace that give us goosebumps and make us tap our foot. Our company's name should remind you this :-) Musicality is not the same as sound quality where it is more about the texture of the sound even though they can be related in sound systems. It is like my son and his teacher playing on the same piano. Sound quality wise, the two are exactly the same, and yet one is more musical than another. Another example is that a Yamaha piano can be as musical as a Steinway in the right hands and yet their sound texture is very different. I have heard some good sound systems with pretty good sound texture and yet it fails to convey the musicality (for instance my ULD15-II).

To reproduce the correct contrast in a sound system, it needs to have the same monotonicity time over time. Low memory effect is the key here. In my son's playing, he has a weak 4th and 5th fingers. So whenever he uses 3rd finger on the current note, you can expect 50% of the time, the next note to be played not as loud as it should be. That is a form of memory effect. That is, the strength of current note depends on the past history of his fingering position. Even though in sound systems, the memory effect is not as bad as in my son's case, But it can still be quite audible. In audio's history, we have 16ohms LS3/5A as a proof. The 16ohms LS3/5A was a success for BBC. Later they come up with a new revision with 8ohms impedance. However, the sound was audibly less dynamic (when I sold my LS3/5A, some potential buyers told me they were only interested in the 16ohm version and mine is not). For those not knowing the inside story may think 16ohms is less a burden to the amplifier and therefore produces a better sound. Actually it is not the case, the root cause was later traced to the new surround material on the 8ohm version. That surround material has a pretty high "creep" effect which is a form of memory effect. In speakers there are at least two forms of memory effects: one is thermal and one is mechanical, such as spider/surround.


Articulation is more related to the time domain response with minimal ringing and minimal boxy sound. One note can be clearly separated from the next notes. In my son's playing, he needs to lift his fingers higher. In sound system, the sound needs to start and stop very fast. The start related to (BL)^2/Re, and the stop is determined by the Q value. A boxy sound from the enclosure can easily make the sound muddy.

Pace again is largely determined by the memory effects. In my sons playing, his 4th and 5th finger is not only weaker, but also slightly slower.

In conclusion, we have a couple of things here: 1) low memory effect, 2) low Q value for the system, and 3) minimal boxy sound. It is not a coincident that our servo subwoofers address all of them.

[Mag_Neato]

Welcome, Brian! I have been enjoying my DIY'd DS12 for over a year now. I appreciate you taking the time to speak with me on the phone regarding the proper amount of polyfil to use in my enclosure and other questions about the operation of the sub.

I noticed on the new subs here that a 1-band PEQ has been included as well as a defeatable rumble filter. I was curious if the power output of the amp has been increased (370W) over the amp I have from a year ago without the PEQ/rumble filter? Also, has the driver changed since then?

Just curious. I am completely happy with the performance, but if there is an upgrade available............

[merrymaid520]

Welcome Brain!

In the other thread we chatted about not using the downfiring D15 on wood subfloors. The F series would truly be perfect in the piano fininsh for alot of us. If its not feasible or along way out, can the D15 be turned on its side?(with the amp up of course

I have been chating with Dave F about your subs and thought I would run this past you also. My current subs is in a 17x17 living area with virtually no walls opening into a 12x18 kitche, then a 17x17 dining room. Will the 15" be sufficient in terms of HT performance. I dont listen at ref levels nor have I every bottomed my current SVS PC Ultra 12" out yet.

Thanks!
Brandon

[RythmikAudio]

Welcome, Brian! I have been enjoying my DIY'd DS12 for over a year now. I appreciate you taking the time to speak with me on the phone regarding the proper amount of polyfil to use in my enclosure and other questions about the operation of the sub.

I noticed on the new subs here that a 1-band PEQ has been included as well as a defeatable rumble filter. I was curious if the power output of the amp has been increased (370W) over the amp I have from a year ago without the PEQ/rumble filter? Also, has the driver changed since then?

Just curious. I am completely happy with the performance, but if there is an upgrade available............

Ed,

The amplifier output is still the same. Only the preamp stage has been redesigned. PEQ is valuable if your room has a significant room mode. Rumble filter is more for those who likes to play really loud or have LP players. If you feel you would be more comfortable with an upgrade, please send me an email and we will figure out what to do.

-Brian

[RythmikAudio]

Welcome Brain!

In the other thread we chatted about not using the downfiring D15 on wood subfloors. The F series would truly be perfect in the piano fininsh for alot of us. If its not feasible or along way out, can the D15 be turned on its side?(with the amp up of course

I have been chating with Dave F about your subs and thought I would run this past you also. My current subs is in a 17x17 living area with virtually no walls opening into a 12x18 kitche, then a 17x17 dining room. Will the 15" be sufficient in terms of HT performance. I dont listen at ref levels nor have I every bottomed my current SVS PC Ultra 12" out yet.

Thanks!
Brandon

The comparison of sealed vs vented subwoofers is a bit difficult because there are weakness in each. The vented box would have more output between 18hz to 40hz band only (EDIT: I made a mistake earlier), and lose to sealed subwoofer below port tuning frequency (for the rumble effect). But I have a few PC Ultra customers, after they hear the sound of our subwoofers, they are pretty much surprised there is such a huge difference. One customer, Kevin, even said our sound is just cleaner, there is no other way to describe it. If you are into sound quality and not into SPL competition, our sealed 15" have plenty output.

BTW, I won't recommend turn D15SE side way, it just doesn't look good. The reason we are still evaluating what to do with a piano finish F15 is that we can use a different driver. If there is any improvement in SPL we'd want to do, the reward is higher if it is done on 15".

-Brian