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Old 11th June 2004, 09:59 PM   #11
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So all your doing is putting an iso-barik sub in your car? Powering it off your deck, and then an amp?
And your deck has a sub-output?

So easy..

No need to line sum, the deck will do that for you, or if your worried, just use one channel of the deck out, and then split that to the right and left of the amp. (You should be able to test by just turning balance all to one side, if both sub outs still have power, then well it's summing in the deck.)
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Old 11th June 2004, 10:13 PM   #12
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or to make damn sure it's summing
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Old 12th June 2004, 11:43 AM   #13
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Quote:
Originally posted by officeboy
So all your doing is putting an iso-barik sub in your car? Powering it off your deck, and then an amp?
And your deck has a sub-output?

So easy..

No need to line sum, the deck will do that for you, or if your worried, just use one channel of the deck out, and then split that to the right and left of the amp. (You should be able to test by just turning balance all to one side, if both sub outs still have power, then well it's summing in the deck.)
First, this is my first time working with a car, and I am not sure what will the deck's sub out will like.

Sub out mode: Left out to left channel sub, right out to right channel sub.

Or Sub out mode: Left and Right in the same signal. And your "balance" trick is quite clever that I only need one channel, but will it sound good? And the summing part is not sure yet. Anyway I will decide rather or not continue this little add-on after I tested the HU.

Second, I think the "active" setting is better because the hu voltage out is pretty low, and the summing will gonna degade the sound too. I also have some OPA2132 laying around, so I want to use them for something. And I finally understand what is buffer. Hehe, I'm too dumb.

Third, I have a little bit of timeto spend on exploring the way of buffer, and circuit design.

Forth, this is all I can think of untill your "balance" trick

Tonight, I watched The day after tomorrow, and the chronico of ridick. It is always why I am posting this at 4:37 West coast time. I got all my wires and connectors, but the fuse and holder. I need to go to homedepot to buy the 6 ga cable for the power supply, and some connectors, but I cna't find 50A fuse and no holder with 6 ga wire wide. I went to radio shack, pet boys, autozone, and homedepot. No luck, none of them carry 50A fuse and holder with 6 ga.
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Old 13th June 2004, 01:50 AM   #14
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if I want to branch testing the amp, do I need to follow the wire spec in the manuel, or I just test it like how I use champ style wire to test my gainclone?
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Old 13th June 2004, 05:48 PM   #15
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Looks like I'm behind on following up... I'm an old man with kids, so sometimes this kind of thing has to take a back seat.
Anyway, S.C, you have some good suggestions from officeboy and sss.

sss wrote:
Quote:
dont u think the next config willgive u better resolts
(zener supply schematic)

I'm surprised no one else has posted alternatives, or even flames. That's why I said:

Quote:
I hate to even post this... But it really does work.
Just be sure current draw isn't too high for the zeners to pass safely. I seriously doubt you'd hear any difference between the two in such a simple application.

S.C asked about decoupling cap highpass results:

Quote:
Are you talking about my design too?
and:

Quote:
So C1 will not do the job. CAn I take it out, and only run one cap on the end of IC B
Yep, and yep. I still haven't really reviewed your original schematic, because of your posted alternative...

Officeboy's suggestions are right-on, I didn't realize your head unit would have a sub output. That was just beggining to happen when I exited car audio years ago! The ones I used were so-so performers, and I almost always opted to add an external crossover for proper frequency selection.

But given your concerns and the spirit of DIY and learning, let's trudge on. I humbly suggest:

-install the amp in normal fashion, use the deck's sub outputs.
-wire the woofers in series, bridging the amp mono into 8 ohms.
-build your circuit, insert it into the system and evaluate the difference.

The second schematic you posted is mixes R+L into the inverting (-) input of the op amp. The inverting input has a very low impedance, hence impedances external to your circuit have less effect on its function. It does invert phase.

All you need to do is change a couple of R values, add the capacitor on the output, and this circuit should work perfectly.

The first IC does the mixing. Resistor tolerance on the R&L lines in need to be as small as practical so their signals mix in equal proportions. The feedback R (3k on your drawing) will set the gain for that section. Gain (ratio of output to input voltage) is simply equal to the ratio of feedback to input resistances.

You can add gain right there, and skip the second IC if you'd like. You have a 2V input and want a 5V output. That's an increase, or gain of 2.5x. For gain of 2.5, use:
feedback R = 2.5x input R's.

If you want to keep the second IC in place and re-invert phase to 0º. You can add gain there instead the same way, with the ratio of feedback/input resistors.

The 100 ohm resistors are there to insure stability in driving cables. If you mount this circuit near the amp and use short RCA cables, they shouldn't be necessary, but it would hurt nothing to keep them in place.

Hope that gives you something to chew on.

I wouldn't run this circuit directly off the remote output. They are low-current outputs for switching only. I'd use a relay or transistor to switch battery power.

Tim
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Old 14th June 2004, 09:54 PM   #16
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Ok, I found out the output of my headunit is both mono even though it is connected with two RCA. So I don't need the summing anymore, but I need buffer! I tested the sub with my amp and headunit, and I notice the lacking of power. I turned the sub volume in my hu all the way to 15, but I can only notice the bass from the trunk in a high moderate level which is disturbing because the tweester is way too loud. Although I had already set the gain all the way down to 0.3Vrms, it is hard to identify the bass from where. Maybe this good cuz it means the system act as a whole. Anyway, I think building a buffer to go with this system will be a good idea cuz I can have a better chance to play around setting.

P.S: I have a question about the sub. The sub enclouse vibrate when I put too less stuffing in it, and play accratly and clear. However, the sub sound unclear, blury, and kinda slow when I put a whole bag of stuffing 20 oz polyester fiberfil in it. It is like you talking in the water, and I am hearind it across a glass.How can I achieve an tight, accrate bass sound with how much stuffing?
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Old 14th June 2004, 10:31 PM   #17
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IF your gain is all the way up, and you still don't have enough volume. Either something is broken, or something isn’t hooked up right.

Considering your sub/amp combo should be good for 113db you should be able to hear that, esp after adding in cabin/room gain.

You sure you have the phase of your drivers right? Maybe pull the top speaker and see if it gets louder with just one hooked up.
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Old 14th June 2004, 10:40 PM   #18
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Yes everything is right. I even tried the difference of different driver being out of phase, nd I like the driver inside out of phase more. I hear the bass that but I just want a bit more, cuz the volume is kinda low when it is in low volume. I start noticeing it clearly when I turned up the volume to 25 which I had never done it when I was driving. or Maybe all this is because of too much stuffing inside which make the bass wide spread(spelling maybe) and unaccurate nor tight. How can do I know when is enough stuffing? Am I just keep adding it just after the enclouse won't vibrate anymore? an How can I mount this round sub on the trunk?
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Old 14th June 2004, 10:48 PM   #19
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Stuffing isn't there to keep the enclosure from vibrating; it's there to kill resonant frequencies bouncing around in the box. I would say that a very small amount of stuffing would do ya just fine.
As to the box vibrating a lot, well IMO a single sonotube without bracing is not adequate for a sub box.
To hold the sub down you could use some type of strapping screwed to the wall of your trunk. Either nylon webbing type straps, or metal “plumbers tape” kinda strapping should work fine.
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Old 14th June 2004, 10:56 PM   #20
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Yead, that true, but what is the most vibratable component on this sub is the outside cone and the outside frame. I don't know why. I can reduce the vibrateion noise by sitting on the endcup and the outside subwoofer drive face down, but some thing still vibrate between the cone and the frame. However, i will add 8 wood stick bracing inside the sonotube to re-enforce the tube like a drum, but the brancing will decreace its volume a bit below the factory spec (.75 sq ft.) Maybe I will build a bit longer on next year haha.
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