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Official Rythmik Audio Subwoofer thread - Page 281

post #8401 of 15160
I may have missed this but, what are the dimensions on the LV12R?

I'm trying to decide between the LV12R, the D15 and the F15. Thoughts on the ported 12 vs the sealed 15's in a medium-sized room?

Also, is the output the same as the discontinued FV12?
post #8402 of 15160
I want to clarify that L12 is basically done. It will be a paper cone driver. The goal is to make it an entry level sealed sub. But the dual-port 12" version is still open to discussion. I think the model can benefit from an aluminum driver because the amount of excursion it can have below tuning frequency. It is not going to be an upgrade option. What I need to decide is if we should stay with paper cone to make it more affordable, or we should make it aluminum cone to make it more bullet proof. The supplier will hate us if we offer too many options.
post #8403 of 15160
Quote:
Originally Posted by nlpearman View Post

I may have missed this but, what are the dimensions on the LV12R?

I'm trying to decide between the LV12R, the D15 and the F15. Thoughts on the ported 12 vs the sealed 15's in a medium-sized room?

Also, is the output the same as the discontinued FV12?

16 (W) "x 22" (H) x19" (D) (20-1/2" D with grille and amplifier knobs)

As for output - this is from the website:

Output comparison

At 20 Hz, our subs vary in their maximum output capability. The output at 20 Hz is shown relative to F12.

F12: 0db (baseline)
F15: +2db D15: +2db
FV12: +3db
E15HP: + 3.5db
F15HP: +4db
FV15: +7db
FV15HP: +9db
F25: +7db

Edit: Brian stated that the specs for the LV12 are the same as the FV12
post #8404 of 15160
So I hooked up the LV12R and have the volume set to 12° clock. Been listening to music, it sounds so good, not going to push it hard for a few days but I love what I have heard so far.

I think I might need a new receiver to get the most out of the sub for movies. My old Sony doesn't have much in the way of bass management. All I can do is set the sub level and set the speakers to small, I have no idea what the crossover is set to on it.
post #8405 of 15160
Thanks, TheLaw - I see it now. Brian - you may want to replace the FV12 with the LV12 on the products -> complete subwoofers page when you get the chance.

I think I'm sticking with the D15, which digs deeper (despite having less output @ 20hz).
post #8406 of 15160
Quote:
Originally Posted by Rythmik View Post


The idea now is we will have a 400WRMS version amp that uses the same footprint as the one used in LV12R. Same function, just replace the power amp module with a higher power Hypex module. With that 400WRMS amp, we can offer sealed version and ported version. The sealed version is planned to retail at $699 (with shipping). The ported version (as being larger than LV12R and with 2 ports), will be $799-849 (with shipping). If we use DS1200 driver in the latter version, the price will increase by $100. This is the rough idea. Of course, I need to negotiate with my suppliers smile.gif

As for power/SPL output, I will do my best to squeeze out the last drop for the performance (and you can trust me for that smile.gif)

I have a 14x18x8 room and I was torn for a long time between dual subs or a more capable single sub. I wasn;t willing to go o ver $2k for the duals. I went with the FV15HP because I wanted to have ultra low bass with plenty of headroom in my high volume capable system. If I had had an option to go with a $1k single sub and add another if needed that would have been a very enticing option, and I suspect more mrket would be available for those set on dual subs - The PSA subs were very tempting in that regard.

That said, I'm extremely happy with the FV15 and it's output and better sound gave more placement options than my previous sub, and the quality of bass is outstanding. The FV was the right choice for me, but for people not willing to go the ful $1550 (after shipping to Maine and paying 15% sales tax to bring to Canada, a $1000 option would be a nice fit. I had a Hsu VTF3mk2 which wasn;t bad and I wasn;t interested in a nominal upgrade such as an FV12.

BTW, to put my opinionin context, I paid the extra $100 for the 600W amp even though I knew I had a very easy room for the sub just because I didn't want to feel like I had less of an amp.
Edited by mikepos - 2/16/13 at 4:53am
post #8407 of 15160
Quote:
If I had had an option to go with a $1k single sub and add another if needed that would have been a very enticing option

curious why you did not go for two F15s as they cost around $1000 with the 10% off with dual subs. I ordered two F12s but then changed my mind to one F15. While I am happey with it I am seriously thinking of checking with Brian and others if adding one F15 /E15 is better or get an FV15 and be done. I can use the F15 for my living room upstairs.
post #8408 of 15160
Quote:
Originally Posted by mikepos View Post

I have a 14x18x8 room and I was torn for a long time between dual subs or a more capable single sub. I wasn;t willing to go o ver $2k for the duals. I went with the FV15HP because I wanted to have ultra low bass with plenty of headroom in my high volume capable system. If I had had an option to go with a $1k single sub and add another if needed that would have been a very enticing option, and I suspect more mrket would be available for those set on dual subs - The PSA subs were very tempting in that regard.

That said, I'm extremely happy with the FV15 and it's output and better sound gave more placement options than my previous sub, and the quality of bass is outstanding. The FV was the right choice for me, but for people not willing to go the ful $1550 (after shipping to Maine and paying 15% sales tax to bring to Canada, a $1000 option would be a nice fit. I had a Hsu VTF3mk2 which wasn;t bad and I wasn;t interested in a nominal upgrade such as an FV12.

BTW, to put my opinionin context, I paid the extra $100 for the 600W amp even though I knew I had a very easy room for the sub just because I didn't want to feel like I had less of an amp.

Well said! My listening area is appox your size except (and thanks CA) I have cathedrial ceilings up to 12' and the area opens up to the rear. But the single FV15 does a great job at it's current location sitting in front of me about 12' away. And I have yet to do the sub crawl. A duel sub setup will not work for me with my house the way it's designed. We don't have basements in AZ, unless your rich of course!

Jeff
post #8409 of 15160
Brian I'm curious, since the F12G is a paper cone sealed 12" sub, in what ways (aside from price) will the L12 differ from the F12G?
post #8410 of 15160
Quote:
Originally Posted by Eldave View Post

Brian I'm curious, since the F12G is a paper cone sealed 12" sub, in what ways (aside from price) will the L12 differ from the F12G?

The driver used in L-series is less expensive. The basket frame is heavy duty stamped frame. This driver was also used in FV12. But I'd like to designate a new series so that we can separate out the entry level subs. We will continue to offer F12. I can expect the sales of F12 impacted by L12, but I think it makes sense to offer L12 and LV12.
post #8411 of 15160
Quote:
Originally Posted by Rythmik View Post

The driver used in L-series is less expensive. The basket frame is heavy duty stamped frame. This driver was also used in FV12. But I'd like to designate a new series so that we can separate out the entry level subs. We will continue to offer F12. I can expect the sales of F12 impacted by L12, but I think it makes sense to offer L12 and LV12.

F12G with paper cone uses a cast frame? whereas the paper cone driver in the LV12R (and L12/LV12 upcoming subs) use the less expensive stamped frame. Cast versus stamped frame is one of the things which I always considered as an indication of price level/ quality (though I'm very happy with the LV12R thus far). Aluminum versus paper cone in itself does not seem to matter as much (both have pro's and con's from what I have read on your site).
post #8412 of 15160
Thanks for the response Brian! Does the less expensive driver result in different specs, like less output or less low end extension? I'm just wondering what difference the end user will experience, audio-wise, when comparing the F12G (or F12) to the L12. I agree the L12 sounds like a good idea.
post #8413 of 15160
The F12G does NOT have a stamped frame driver, it's a GR Research high quality paper-cone/cast-frame driver, same as the driver in the Rythmik F12 except with a paper cone instead of an aluminum one. The driver in the LV12 is a different driver.
post #8414 of 15160
Quote:
Originally Posted by rsmt2000 View Post

curious why you did not go for two F15s as they cost around $1000 with the 10% off with dual subs. I ordered two F12s but then changed my mind to one F15. While I am happey with it I am seriously thinking of checking with Brian and others if adding one F15 /E15 is better or get an FV15 and be done. I can use the F15 for my living room upstairs.

The cost for 2 F15s would also require double shipping and 15% sales tax to get them into Canada (I live near the border and ship to a US border town), with ran several hundred more than the FV15. I was torn between the two options for a few days but finally went with the single sub, mostly because I wanted to be sure to have strong low bass because I figured the sub would work well near the middle of the rear wall, based on experimenting with the Hsu VTF3mk2. The Hsu was more flat there but lacked the output, the FV15 is doing fantastic except it annoys people upstairs, but that's not a big concer:pn.
post #8415 of 15160
Quote:
Originally Posted by Flatliner View Post

F12G with paper cone uses a cast frame? whereas the paper cone driver in the LV12R (and L12/LV12 upcoming subs) use the less expensive stamped frame. Cast versus stamped frame is one of the things which I always considered as an indication of price level/ quality (though I'm very happy with the LV12R thus far). Aluminum versus paper cone in itself does not seem to matter as much (both have pro's and con's from what I have read on your site).

The cast frame adds to the cost. I was a bit concerned that the stamp frame gasket may add too much coloration. However, this particular gasket that the supplier selects is heavier duty (thicker gauge steel). After i tested it against F12, it is close in terms of sound quality. I think the customers can hear the improvement too. The forumula that we have to make servo subs sound good are all in these entry level subwoofers. And from LV12/L12 to F12 you can get incremental improvement. In the ideal world, I would like to have everyone move to the D-, E- and F- series subs. But there are customers with limited budget. We need to do our best within that budget. It is a different challenge to us.

-
Edited by Rythmik - 2/16/13 at 3:29pm
post #8416 of 15160
Wondering about DirectServo for vented boxes... With a sealed box, cone movement translates directly into audio output, so it is easy to see how controlling cone movement will linearize response and improve distortion.

With a vented box, cone movement at tuning resonance is greatly reduced. Virtually all the output comes from the port. In this case, it seems DirectServo may not have a big effect on linearity. I can see that servo can still affect T/S parameters, but how well does it reduce THD at resonance? Or maybe distortion from the driver at resonance is not so important, and the linearity of the cabinet/port dominates?

It appears that the 15" CI models can support both sealed and vented. What is the difference in servo control between these versions? Based on the above paragraph, is there a difference in level of servo control at or above cutoff frequency for sealed vs. vented? I realize there is not much you can do with vented below cutoff.Does the vented version have a limiter to avoid driver damage below cutoff?

Zaph Audio (www.zaphaudio.com) has lot of measurements of hobbyist drivers (but not much for subwoofers). I agree that distortion characteristics explain a lot about how a driver sounds.
http://www.zaphaudio.com/nonlinear.html

I am wondering about the effectiveness of DirectServo on higher order distortion components that are more objectionable. I can imagine servo helps 2/3rd order a lot, but higher order problems may be due to mechanical cone/suspension/motor issues that are not as easily corrected. As an aside, I saw a note that the LV12R has a lower quality driver than the F12G. Perfectly reasonable, of course. Are the audible differences due to these kind of higher order issues that are harder to correct?

Or maybe DirectServo helps across the board (e.g. lowers distortion of all orders by X db), but if the driver starts off with lower numbers it remains lower after correction. What level of improvement is typical (what is "X")?

I guess the question is whether competitive products with a high quality driver without servo (but perhaps with limited EQ) can be equivalent to a driver with servo.
post #8417 of 15160
Brian

From your previous post some time back


Quote:
I would not recommend setting the volume on the plate sub at 9 o'clock unless you have very inefficient front speakers. The more efficient the front speakers are, the higher the volume setting you need on the sub channel which you can achieve either from the AVR or from volume knob on the plate amp. There are basically 3 scenarios: 1) set the AVR sub level to positive db and then turn down the volume on the plate amp, 2) set the AVR sub level to neg db and then turn up the volume on the plate amp, and 3) set the AVR sub level to 0db and adjust the volume on the plate amp to match the level it is supposed to be. The first scenario is the least desirable and you may overload the AVR preamp output too. The best scenario is 3). If you have a roomEQ with AVR, adjust the volume on the plate amp until the roomEQ set the sub level same as the two front channels which is normally 0db.



When I change the volume knob on my F15 to get back 0db for the sub channel output running audessey, the front chanels are coming to -8db -7.5db -8.5db etc. From your post above, you say the two front channels should also be around 0db. Does it mean I have my subwoofer located in a null?
post #8418 of 15160
Quote:
Originally Posted by go94022 View Post

Wondering about DirectServo for vented boxes... With a sealed box, cone movement translates directly into audio output, so it is easy to see how controlling cone movement will linearize response and improve distortion.

With a vented box, cone movement at tuning resonance is greatly reduced. Virtually all the output comes from the port. In this case, it seems DirectServo may not have a big effect on linearity. I can see that servo can still affect T/S parameters, but how well does it reduce THD at resonance? Or maybe distortion from the driver at resonance is not so important, and the linearity of the cabinet/port dominates?

First off, I had a post a few pages back about how I started Directservo as a patent. Before that is certainly years of experiments (just like everyone else before we working on servo, ad hoc or trial and error and only on one type of speakers -- sealed speakers). One day I thought there got to be a way to formulate the problem (after all, that is how we are trained in graduate school), and then I was able to formally formulate the problem of "servo feedback" and best of all, it can all be explained in the context of T/S parameters frame work. I have told some customers that the effect of servo feedback from accelerometer is it creates a large equivalent moving mass. Customers of Velodyne servo subs (I had ULD15 II in 1990s) can push their cone and do the experiment. The problem with creating a large moving mass is once you push it hard enough to start the mass-spring oscillation; it is hard to make it stop unless you have sufficient damping.

Anyway, so I started the process of filing the patent with the whole idea of protecting the intellectual property by the patent book by Pressman. It clearly describes you can file patent to protect your IP, for others that you cannot file patents for, just keep your mouth shut (which is called trade secrets) is the conclusion. So you will see that I don't openly discuss our patents beyond what is disclosed in the patent.

So back to your question, the problem you have described for vented sub is only there when you apply infinite servo loop gain. If we reduce the loop gain just enough (but still significant), it will work for ported subs too. It turns out today’s ported subs, without any boost, all have very weak output at the port tuning frequency point (unless you go with 300L box). And that is the opportunity for the servo to come in play.



Quote:

It appears that the 15" CI models can support both sealed and vented. What is the difference in servo control between these versions? Based on the above paragraph, is there a difference in level of servo control at or above cutoff frequency for sealed vs. vented? I realize there is not much you can do with vented below cutoff.Does the vented version have a limiter to avoid driver damage below cutoff?

The servo boards are different for vented and sealed subs (and for OB/IB). So the cutomers need to specify which mode of operation he wants. There are simple conversion steps you can do to convert from one version to another.
Quote:
Zaph Audio (www.zaphaudio.com) has lot of measurements of hobbyist drivers (but not much for subwoofers). I agree that distortion characteristics explain a lot about how a driver sounds.
http://www.zaphaudio.com/nonlinear.html

I am wondering about the effectiveness of DirectServo on higher order distortion components that are more objectionable. I can imagine servo helps 2/3rd order a lot, but higher order problems may be due to mechanical cone/suspension/motor issues that are not as easily corrected. As an aside, I saw a note that the LV12R has a lower quality driver than the F12G. Perfectly reasonable, of course. Are the audible differences due to these kind of higher order issues that are harder to correct?

Now that is another area that we keep as a trade secret that I will not go in details to explain how servo help reducing higher order distrortion. It is a simple math observation. The method/insight is mentioned in one of AES papers, but it was used in a different area (in distortion component simulation). But let us just say, indeed the distortion reduction is also effective on higher order distortion. If you check the comparison of distortion comparison on our websiste, you can see the more consistent improvement is on higher order harmonics, exactly where we need.
Quote:

Or maybe DirectServo helps across the board (e.g. lowers distortion of all orders by X db), but if the driver starts off with lower numbers it remains lower after correction. What level of improvement is typical (what is "X")?

I guess the question is whether competitive products with a high quality driver without servo (but perhaps with limited EQ) can be equivalent to a driver with servo.

A high quality driver is always a necesary part in my formula. If we started with a less quality driver (like those off the shelf from my suppliers), the poor quality is sufficient to cast a masking effect on the final sound quality. So my view is very different from anyone else who wants to use servo sub as a gimmick. Chad once talked to me that he wants to license our patent. During the conversion, all he talked about is the "lowest distortion" number technology (completely ignore the part of "how to make good sound" discussion, which to me is more exciting). His intent is very obvious. A lot of people wants superficially low distortion number. Is the low distortion the key to good sound? Absolutely not. That is just one layer of onion. After that we come to the next layer which is time coherence. So what servo improves goes beyond the simple distortion numbers. What we improve furthers is in spider/surround memory effect, and thermal memory effect, and how to maintain very good cone control in the presense of standing waves and reflections.

Engineers are in general very poor statisticians. They view the world as black and white. If they can just for a moment believe that the characteristics they observe at time t can be slightly different from time t' and start thinking how to improve that, or .. if they ever view each individual sub having a slightly different characteristic and try to come up with a way to narrow that difference (to create a consistently good product too), or start to recognize it is difficult to tell the difference between correlation (like hearing the result of good quality sound) and causation (engineers want to find the exact reason leading to good quality sound) in statistical observation. It is just like the great Albert can never embrace quantum physics because he does not believe god will throw a dice on us. But inject a bit of statistical view help engineers.

Bill has posted a video link a few pages back. The presenter talked about the experiments that he has when he has a control to flip a switch and how people are fooled. But if some one look at the scatter plots with x axis be the real physical difference and y axis be the observed sound quality difference, this presenter only talks about the spread of y axis at a single x point. In the real life, A-B comparison is like look from the y axis, when we observe a difference (which mapped to a y value) ,then what is the chance of having a real world difference (the spread on the x-axis)? They are two totally different questions.

Now, everytime members bring up the issue of sound difference compnents, interconnects, and blah blah, it always leads to heated discussion. In the back, I would hav said "cool down guys, the observation you guys have is statistical insignificant to reach any meaningule statistical conclusion".

In the end, all the above is why these days I spent more time on customer service than to do any technical debates.


-
Edited by Rythmik - 2/17/13 at 1:17pm
post #8419 of 15160
Brian
After 40 days of waiting (yes, I'm living in the Old Word), I'm finally get the 1505CI driver for sealed enclosure, and have some questions.
Can I use for that woofer the plan from next link? I'm in doubt, because in this .pdf the volume of enclosure is 4 cu.ft., but on your website description requires- 3 cu.ft.confused.gif
Thanks.
post #8420 of 15160
^^^

3 cu ft to 4 cu ft is what we recommend. Please don't be concerned about it. I don't know what happened to Russian post service. It does not usually take that long to get there.
post #8421 of 15160
The Russian Post absolutely not guilty, because I'm from Ukraine (it's near the Russia) and I used an intermediary for the shipment.biggrin.gif I knew the timing of delivery, so, don't worry.wink.gif
I'm almost done the transfering drawings to metric (using SW2011), so, can provide it to you, if you want, in desirable format.
post #8422 of 15160
Quote:
Originally Posted by rsmt2000 View Post

Brian

From your previous post some time back




When I change the volume knob on my F15 to get back 0db for the sub channel output running audessey, the front chanels are coming to -8db -7.5db -8.5db etc. From your post above, you say the two front channels should also be around 0db. Does it mean I have my subwoofer located in a null?

The sub can be in a null or your front speakers have high efficiency. Turning down the volume control on the plate amp should help. You don't need to get to exact 0db point, anything between +/- 6db is reasonable.
post #8423 of 15160
Quote:
I'm almost done the transfering drawings to metric (using SW2011), so, can provide it to you, if you want, in desirable format.

Please send me the pdf version after you are done. It will help other customers.
post #8424 of 15160
Bit of a delayed update from Friday. Tried the LV12R out with a few different movies - Serenity, Master & Commander, some BSG, Open Range, and Lord of the Rings. It's as adept at movies as it is with music, going deep without any strain and moving enough air to set the front door knocker vibrating. Definitely very happy with this sub.
post #8425 of 15160
^^Awesome. Have not seen an unhappy Rythmik owner yet.
post #8426 of 15160
I played the famous Black Hawk Down Irene scene with my FV15HP and did not hear or feel bass at all. Anyone here plays that scene? I have all of those five star bass movies and this is the only movie that my sub did not do much. I guest it takes more than a FV15hp to feel that single digit sound from BHD.
post #8427 of 15160
Although I don't own a Rythmik sub I believe Brian makes some awesome products. I have to say that its great to see stuff like Brian posting in what is basically his thread seeing that he's the man behind Rythmik and stuff like Tom posting in the PSA thread. I think he's great for the customers and the ID industry to see stuff like this happen. Helps cover up the black eyes some ID companies or company have put on the ID portion of the industry. As consumers these are great and exciting times for the audio market!
post #8428 of 15160
Quote:
Originally Posted by Cowboys View Post

I played the famous Black Hawk Down Irene scene with my FV15HP and did not hear or feel bass at all. Anyone here plays that scene? I have all of those five star bass movies and this is the only movie that my sub did not do much. I guest it takes more than a FV15hp to feel that single digit sound from BHD.

Glad Im not the only one...What gives??Id assume its because that is suppose to be around 7 hz and the FV15HP doesnt go that low?? confused.gif
I did do that when I first got my FV15HP a few days ago with one port open.I have since gone to 2 ports open and had an ear to ear smile during the "train Wreck underground" scene in Skyfall..Will revisit BHD also.
post #8429 of 15160
Quote:
Originally Posted by GIXX1300 View Post

Glad Im not the only one...What gives??Id assume its because that is suppose to be around 7 hz and the FV15HP doesnt go that low?? confused.gif
I did do that when I first got my FV15HP a few days ago with one port open.I have since gone to 2 ports open and had an ear to ear smile during the "train Wreck underground" scene in Skyfall..Will revisit BHD also.

the nature of every ported sub is that if it receives significant input below the port tuning, the woofer itself is unloaded so no air spring to control it, and it will destroy itself if exposed to those frequencies. So there is a sharp high pass filter to protect the thing from self destruction below the tuning frequency.
post #8430 of 15160
The 7hz in BHD is extremely difficult to produce at the required SPL for it to be perceived even with multiple powerful sealed subs. For vented subs with a tuning frequency above 7hz, it simply cannot be re-produced.
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