You can do it without active components as well (opamps, transistors, diodes, etc). This approach will probably not sound as good because of lower impedances on both input and output, which will (might) strain your cd-player and power amp. But since it is soo easy to try and virtually free, go ahead and do it. Just remeber to turn the potentiometer (or rotary switch if you prefer) to its lowest position (least resistance). This will make sure the subwoofer amp and/or sub isn't blown to bits. Gain will always be lower than one with the passive solution. And yes, the triangular thing is an op-amp (just about any will do).
/Niclas
/Niclas
Attachments
stappvargen, What if I say I have 3 OPA2132 laying around. Can I use it one the Sum block, and how will I gonna do that? Am I just connect power to the opamp and the rest follow the schemet(spelling) but the OPA2132 is a dual opamp. What will be a way to use both in and out?
SO the finally connection graph will look like this, right? Pre-amp sub two channel out-> Summing block-> Y-adapter-> stereo amp input which were inputing mono signals-> each sub drive.
Or
Pre-amp sub two channels out (may be even throu mode which has no Low Pass) -> Active Summing block+ high cut to 40hz-500hz) which is exactly the same as spec-> Y-Adapter -> Stereo amp input-> stereo output (thou mode too) -> sub in seperate channel.
DO I need the crossover after I have an active one. If I have an active one, the crossover on the HU, and amp can left out, right?
SO the finally connection graph will look like this, right? Pre-amp sub two channel out-> Summing block-> Y-adapter-> stereo amp input which were inputing mono signals-> each sub drive.
Or
Pre-amp sub two channels out (may be even throu mode which has no Low Pass) -> Active Summing block+ high cut to 40hz-500hz) which is exactly the same as spec-> Y-Adapter -> Stereo amp input-> stereo output (thou mode too) -> sub in seperate channel.
DO I need the crossover after I have an active one. If I have an active one, the crossover on the HU, and amp can left out, right?
Sorry, I don't quite understand what you are saying. Do you have a pre-amp with sub-out or don't you? If you don't you will need to extract the low frequency information from both left and right channels. A way to accomplish this would be like the picture I attached in post #18 (there are several other ways, just do a search on google.com). And in that case your OPA2132s are PERFECT for the job. You will only need to use 2 of your OPA2123s since they are, as you stated, a dual opamp. The part after the Active Eq (in the picture), goes to your stereo amp (for the sub), just make two connections from the Active Eq to the left and right input of the stereo amp driving your subs. Now each JBL will have a separate amplifier to drive it. I can't make it any clearer than this. Maybe someone else can?
/Niclas
/Niclas
Ok, Let me discrible my system.
Kenwood KDC-MPV5205: 4 Pre Out, Fron and Rear. Rear pre out can switch to be a sub out, but I still need to connect it with stereo RCA. I think it is 2.5V output.
Blaupunkt PA2150: Stereo input, I can use mono input to the right channel while the amp is bridged but that's not what I want because the 4-ohms to 2 ohms problem that the amp will be unstable on 2 ohms.
I want to make the sub drive relativly to each other but not one on right channel and the other on left channel.(Maybe now I making them equal to each other but not relative to each other?) So I need something to combine the stereo sub pre out to mono, and split it to two input to my amp and out to my sub seperately with same output. Will that achieve the "Out of Phase" like connection? If it can't achieve this "Out of Phase" like connection, what will this sub become?
Kenwood KDC-MPV5205: 4 Pre Out, Fron and Rear. Rear pre out can switch to be a sub out, but I still need to connect it with stereo RCA. I think it is 2.5V output.
Blaupunkt PA2150: Stereo input, I can use mono input to the right channel while the amp is bridged but that's not what I want because the 4-ohms to 2 ohms problem that the amp will be unstable on 2 ohms.
I want to make the sub drive relativly to each other but not one on right channel and the other on left channel.(Maybe now I making them equal to each other but not relative to each other?) So I need something to combine the stereo sub pre out to mono, and split it to two input to my amp and out to my sub seperately with same output. Will that achieve the "Out of Phase" like connection? If it can't achieve this "Out of Phase" like connection, what will this sub become?
OK. Now I see.
So if you use the rear out as a sub out just use the Summing block (Stereo -> mono) as can be seen in the picture in post#18. This means that you only need to use one op-amp of a OPA2132 to accomplish this. Hope you know how to hook up a op-amp (you need +-rail voltage, + decoupling at the op-amp, see datasheet for 2132: http://focus.ti.com/lit/ds/symlink/opa2132.pdf). Make sure you get the gain you want. Look in the picture in post#18 and you will see how this is acheived for an opamp with positive feedback.
So just feed the output from the Summing block to the left and right channel in to Blaupunkt PA2150 and use a channel for each JBL. The out of phase connection is acheived as Ferdi in post #2 says, by reversing the polarity from the output of the Blaupunkt PA2150 to the JBL (connect the red output of one channel to the black input of the JBL and visa versa and you have it). Do this on the one you want phase shifted! That should do it.
/Niclas
So if you use the rear out as a sub out just use the Summing block (Stereo -> mono) as can be seen in the picture in post#18. This means that you only need to use one op-amp of a OPA2132 to accomplish this. Hope you know how to hook up a op-amp (you need +-rail voltage, + decoupling at the op-amp, see datasheet for 2132: http://focus.ti.com/lit/ds/symlink/opa2132.pdf). Make sure you get the gain you want. Look in the picture in post#18 and you will see how this is acheived for an opamp with positive feedback.
So just feed the output from the Summing block to the left and right channel in to Blaupunkt PA2150 and use a channel for each JBL. The out of phase connection is acheived as Ferdi in post #2 says, by reversing the polarity from the output of the Blaupunkt PA2150 to the JBL (connect the red output of one channel to the black input of the JBL and visa versa and you have it). Do this on the one you want phase shifted! That should do it.
/Niclas
See if I understand this, I will need to connect one of the sub in polarity like left channel + to Sub +, - to Sub -. After that I connect the other sub in different polarity like right channel + to Sub -, and - to Sub +. Am I right? Now at least I can keep everything together without spending more time and money to return stuff and buy some more.
However, I'm confuse with all the crossover now. My headunit over HP LP filter, and I need to build the active high cut(LP filter) to achieve a better load form source, then there is one more LP filter on the amp.
Later, I finished this confusion, I will have the head unit volume control, Active Eq volume control, and the amp gain control.
Which do I really need and which one don''t?
However, I'm confuse with all the crossover now. My headunit over HP LP filter, and I need to build the active high cut(LP filter) to achieve a better load form source, then there is one more LP filter on the amp.
Later, I finished this confusion, I will have the head unit volume control, Active Eq volume control, and the amp gain control.
Which do I really need and which one don''t?
Reguarding summing the inputs, all of the amps I've used will sum the left and right input when you bridge the outputs, so double check the manual before you go thru all that trouble to combine them before they reach the amp.
As for the xover, why not just use the one in the amp? If your headunit has an adjustible low pass xover you can raise the xover point on the amp a bit and make fine adjustments with the headunit xover as you listen to different music if you want.
As for the xover, why not just use the one in the amp? If your headunit has an adjustible low pass xover you can raise the xover point on the amp a bit and make fine adjustments with the headunit xover as you listen to different music if you want.
DC Dave said:
Hm.... Good pt, I can actrually split the bridged mode setting, and connecting the speaker seperately as describled. This will not cause "the 4 ohms to 2 ohms" problem, right? Since the driver is not parallel connected.
So I will be either use pre-amp->active summing block(no EQ)-> Amp-> sub
or Pre-amp-> Amp-> a way to spilt the bridged mode output to one drive in polarity, and the other in reverse polarity, right?
Sorry for the double posting. After I think about it, I still need to sum it before amp because the problem with this amp is it can't drive 2Ohms stablly. As you said, DC Dave, the amp will bridge the stereo to mono, but it won't be able to drive the sub parallel that decreasing both 4 ohms drivers to 2 ohms. However, summing block will be able to brdige(summing) the stereo to mono first, and feeding the amp with the same mono signals to both left and right, and then the amp will act like a mono block for each drive with similar sources. I think this is the final answer to my problem. Btw, I found some place have the same amp with cheaper price, and I reported it to get my 11.xx back 🙂 (Best Price Gruantee) I like that!
I understand what you are doing now. I was thinking that you were going to bridge the amp outputs to one channel and connect the speakers in series resulting in an 8 ohm load. You could try it both ways to see what gives you the best results.
Ppl can come to this new thread to help me out on the summing block design. Car audio froum
Nice to know that I get it right. Then I need to work on the summing block now. I think I will use IC 1b as a voltage follower. Anyway let's make the off topic subject to other forum.😉
Nice to know that I get it right. Then I need to work on the summing block now. I think I will use IC 1b as a voltage follower. Anyway let's make the off topic subject to other forum.😉
Ok I have a problem. I branch tested the amp with bridge out series ohms connection and set the LP filter to 50-250Hz
(no bass boost). I heard some unwanted vibration between components. I can reduce some of it by facing the magnet on the ground and sitting on it, but there are some more. When I reduce the LP to 50-100/120 Hz, there were less vibration, but still noticeable if I don't sit on it. I only stuffed a little bit poly fill into it. What is the cost of vibration? Is it the outside driver cone vibrate? Is it the gasket ring vibrate (I already tightern up a lot more, and it reduce some vibrate noise)? Is it the Endcap? Is it just the sonotube? Or Is it the speaker wire inside?
What is a good way to test which vibrate, and which is not? Will it be a good idea to test the cone out by assembling obly the gaskit and the drivers, and left out the enclouse to see if the drivers vibrate or not? Or I should add more stuffing?
(no bass boost). I heard some unwanted vibration between components. I can reduce some of it by facing the magnet on the ground and sitting on it, but there are some more. When I reduce the LP to 50-100/120 Hz, there were less vibration, but still noticeable if I don't sit on it. I only stuffed a little bit poly fill into it. What is the cost of vibration? Is it the outside driver cone vibrate? Is it the gasket ring vibrate (I already tightern up a lot more, and it reduce some vibrate noise)? Is it the Endcap? Is it just the sonotube? Or Is it the speaker wire inside?
What is a good way to test which vibrate, and which is not? Will it be a good idea to test the cone out by assembling obly the gaskit and the drivers, and left out the enclouse to see if the drivers vibrate or not? Or I should add more stuffing?
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