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audio amateur
03-04-2006, 06:07 AM
I just ordered the sony Xplod XS-L121P5S car subwoofer rated at 350W RMS (4 ohm single VC) to use in my "DIY" project. I'm planing on building a home sub, with this driver. I was searching a sub "plate amp" and I finally came up with the Rythmik audio 350 :

http://www.rythmikaudio.com/nonservo_product.htm#350basic

Do you think this is a good match for the sub? Is this a good amp? Also, the inner volume I am planing to make it about 1.6 cubic feet, with a 4 inch diameter port which would be 10 inches long, in order to give a box frequency of about 40 hz. Does this sound good? The only problem is that I dont know what sony recomends as far as inner volume for this sub in a ported enclosure... I think 1.6 is fairly big for this sub. but if I want a box tuning frequency of 40 or less I need to keep it this way, considering the fact that I cannot have a longer port because of box dimension restrictions..
My primary concern is the amp.Thanks for posting for any comments.

N. Abstentia
03-04-2006, 09:07 AM
I don't think you'll be happy with that sub. Is it too late to cancel the order? Why would you order a car sub (and such poor car sub to boot) to use in a house?

audio amateur
03-04-2006, 09:34 AM
hmmm well good question. To be honest I doubt it's as bad as you think it is, I have read reviews on it and it seems to hit fairly well, and the sound quality can't be that bad. I do have money restrictions as a I am in high school, and I have found few french web-sites (as I am living in france) that sell subs this cheap (at lest ones that are in its league). Anyhow, I have done a bunch of research and I don't think I'm going to cancel order, because I doubt i'll find any better for the price. I guess i am quite attracted to the design of it, and it's specs seem to match what I am looking for, even though it is quite cheap. Do you have any alternatives in mind? comming back to the amplifier, please tell me what you think (you or any others of course), because I am not familiar with the brand.

N. Abstentia
03-04-2006, 01:22 PM
Well the problem is, it's designed to work in a car..not in the house. Not saying it won't work at all, but it's just designed to work in a tiny enclosure in a space that is very small (your car) and enclosed. Car subs depend on your cars natural boost of low frequencies, which is why they don't have much output below 50hz. Your room is completely opposite...it needs a sub that can move tons of air, and car subs don't.

audio amateur
03-04-2006, 02:36 PM
Perhaps your right... I'll give you feed back once it's done.. however im still concerned about the amp. Anyone have any experience with Rythmik audio amps?

kexodusc
03-05-2006, 03:50 AM
Perhaps your right... I'll give you feed back once it's done.. however im still concerned about the amp. Anyone have any experience with Rythmik audio amps?
Nothing wrong with the amp at all. I worry it might be too much amp for the woofer you're using. Does the sony woofer have t/s parameters? That's really the only way to guess any kind of performance or required box size.
N. Abstentia is right. Car subs are designed to work in small enclosures and get loud. Sound quality in a house probably isn't something it was designed for, but that doesn't mean it won't be okay.
But if you have any other options, I think you'd be doing yourself a favour. Decent woofers aren't very expensive, especially in Europe where some of the best driver manufacturers are.

audio amateur
03-05-2006, 05:55 AM
In-Car Measured SPL (peak @ 50 Hz): 1 watt: 105.1 dB; 350 watts: 127.6 dB; 1200 watts: 130.3 dB
Published Specs: XS-L121P5
Max Power (W): 1200
Max Power (RMS, W): 350
Sensitivity (dB/W/m): 89
Freq. Resp.: (Hz) 18 - 2k
Impedance (Ohms): 4
D (mm): 250
D (inch): 9.8
Rdc (Ohms): 3.2
Fs (Hz): 26.4
Qts: 0.42
Qes: 0.44
Qms: 5.86
Vas (Lit.) : 55.5
Vas (ft_): 1.96
Mms (g) : 219.0
Lvc (mH) : 1.2
Xmax (mm) : 7.5
Xmax (inch) : 0.3
BL (Tm) : 16.1
General Info: 12-inch Polypropylene Cone
Weight: 12 pounds 10oz
Mounting Diameter: 11.0 inches
Mounting Depth: 6.375 inches

Here are the thiele/small parameters you were asking for Kexoducs. If ever you think you have any ideas about the box construction, in accordance with the T/S specs, please let me know, I would be grateful. I have downloaded a software for box constructing (called win-ISD (the beta and alpha pro versions)), but they seems to be faulty, and in my point of view are crappy... i think it's too old, but I do admit I haven't really taken the time to really play around with it. Could you suggest a web site from the which I could download such a program (preferably free..)? To be honest I do not know of many brands who sell seperate sub drivers for DIY projects. Thats my problem. If you know of sites that do sell them, please tell me (I do know of parts express etc.. but these are american).

kexodusc
03-05-2006, 06:45 AM
Here are the thiele/small parameters you were asking for Kexoducs. If ever you think you have any ideas about the box construction, in accordance with the T/S specs, please let me know, I would be grateful. I have downloaded a software for box constructing (called win-ISD (the beta and alpha pro versions)), but they seems to be faulty, and in my point of view are crappy... i think it's too old, but I do admit I haven't really taken the time to really play around with it. Could you suggest a web site from the which I could download such a program (preferably free..)? To be honest I do not know of many brands who sell seperate sub drivers for DIY projects. Thats my problem. If you know of sites that do sell them, please tell me (I do know of parts express etc.. but these are american).

I'm not a big fan of WinISD...try finding Unibox...I find it easier and bit better. A google search should show you were to get it.
In Europe, I'm not sure where you'd order drivers from, but diyaudio.com might be a good forum to ask that question in.

I came up with a volume of 90 litres (about 3 cubic ft, tuned to about 22 Hz very quickly...I'm pretty sure your 1.6 cubic feet is a bit too small...but you can check that yourself once you get unibox...I think you could go as low as 60 litres though (2.1 cubic ft)...from the numbers you gave me, this thing likes big boxes...it isn't unusual for a woofer this size.

audio amateur
03-05-2006, 08:25 AM
I'm not a big fan of WinISD...try finding Unibox...I find it easier and bit better. A google search should show you were to get it.
In Europe, I'm not sure where you'd order drivers from, but diyaudio.com might be a good forum to ask that question in.

I came up with a volume of 90 litres (about 3 cubic ft, tuned to about 22 Hz very
quickly...I'm pretty sure your 1.6 cubic feet is a bit too small...but you can check that yourself once you get unibox...I think you could go as low as 60 litres though (2.1 cubic
ft)...from the numbers you gave me, this thing likes big boxes...it isn't unusual for a woofer this size.

WOW! 3 cubic feet is huge! are you sure your right about this? on the car domain site they recommend 1.5CF.But I'll know anyway once I get the sub, hopefully in the manual they will say. My only problem is port length, it can't be superior to 10 inches 'cause the inner width of the box will be about 12 inches as well as 12 for the height (im planing on putting a 4 inch diameter port). The only the thing I can make longer is the depth. But true, I might make it a little bit deeper, and a bigger box means more output so it can't be bad. But if I come to realise the box is actually too small, I can always put some polyfill to "make it bigger". thanks for your help. I've tried to download a bunch of excel spreadsheets from the unibox website but all it is is excel read-only documents... I can't put in the sony's specs in...
By the way, lower tuning frequency means deeper bass output right? The is my first DIY project so I want to be sure I make it right.
I'll ask you one last favor if you may... I have other T/S parameters, which I actually think are the correct ones for this sub:

frequency response (Hz) 18-2000
sensitivity (db/w/m) 89
nominal power(Watts RMS) 350
Impedance (ohm) 4
d (mm) 250.0
d (inches) 9.8
Rdc (ohms) 3.3
Fs (Hz) 22.6
Qts 0.51
Qes 0.55
Qms 5.59
Vas (liters) 102.1
Vas (cubic meters) 3.25
Mms (g) 183.3
Lvc (mH) 1.4
Xmax (mm) 11.5
Xmax (inches) 0.5
BL (Tm) 12.5

Could you see what inner volume would be best ? thanks a bunch.

kexodusc
03-05-2006, 09:07 AM
Changing the T/S parameters changes everything...I should have caught this before - the spec D at 250 mm, what is that? Piston area?
If so, it's aweful small for a 12".
Does Sony recommend this in a ported enclosure? I'm sorry, I just downloaded unibox on my laptop here, so maybe I have a bug, but I can't see this fitting in a 1.5 cf box. maybe in a car if Sony takes cabin gain into consideration...maybe.

I'm wondering if the t/s specs they give are accurate? Sony specs can be suspect at times.

This might just come down to the fact it's made for cars and won't work well in your home. In which case you're best off finding another woofer.

kexodusc
03-05-2006, 12:16 PM
No, sealed enclosures are generally a fair bit smaller than ported enclosures for the same woofer...I was just wondering if maybe they recommended 1.5 cubic ft in a sealed enclusure...a lot of car subs are sealed, to take advantage of cabin gain.

audio amateur
03-05-2006, 12:19 PM
D actually stands for "Effective diameter of driver, in meters"...

True, I guess It is possible to have a small enclosure if it's for car use.. This being I guess I am better off using a bigger box than 1.6cf if I want any good results. My only worry is "boomy" sound if the box is too big and all the other negative aspects of boxes that are too big.

The reason I gave you the other t/s specs I found is because the XS-L121P5S i ordered is the the silver colored version of the basic XS-L121P5, thus the "S" at the end of the model number. On a french web site , I found different T/S specs for the S version, which is the same model as the normal XS-L121P5 which is red. bizar... However I'm pretty sure the first t/s specs I gave you are the right ones.

Were you thinking of a sealed enclosure when you were mentioning the 3cubic feet?

N. Abstentia
03-05-2006, 01:23 PM
The piston area may look strange because this is actually one of those octagon shaped woofers. It's not round.