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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > AUDIO/VIDEO + BLUETOOTH + Electronics/Alarm/Software > VP Electricity finally gets audio in his own car!



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      03-09-2010, 02:32 PM   #89
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VP_Electricity, with all of those amps and components, how do you ensure that you are not pulling the battery output down in a way that it would underpower (or cause power anomalies) for the other devices in the car?

I am just wondering what can be done to lower the chances of the presence of an amp being used as an excuse to void a warranty.
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      03-09-2010, 02:42 PM   #90
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Well, nothing dims, and I calculated the draw and it seems to be OK.

All the amp channels are being loaded at 4 ohms, and so the amps all pull far less than their max current draw.

In a 1-series, I would worry a bit more, as the battery is smaller and I suspect the alternator isn't as beefy.

But with a system this extensive, you are running a risk on that score, since we are all at the mercy of the service department looking at the car. Most of what I do for customers comprises a single 4 or 6-channel amp and I think the risk is minimal. But I really wanted to try something different this time.

If you were really concerned about current draw, you could use an external processor such as a bitone or a DSP-6, and then use Class D amps instead of Class AB amps, which are much more efficient and thus draw much less current per watt of ouput. IMO, some sound better than others. I'm testing some out now...
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      03-09-2010, 07:41 PM   #91
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Quote:
Originally Posted by VP Electricity View Post
Well, nothing dims, and I calculated the draw and it seems to be OK.

All the amp channels are being loaded at 4 ohms, and so the amps all pull far less than their max current draw.

In a 1-series, I would worry a bit more, as the battery is smaller and I suspect the alternator isn't as beefy.

But with a system this extensive, you are running a risk on that score, since we are all at the mercy of the service department looking at the car. Most of what I do for customers comprises a single 4 or 6-channel amp and I think the risk is minimal. But I really wanted to try something different this time.

If you were really concerned about current draw, you could use an external processor such as a bitone or a DSP-6, and then use Class D amps instead of Class AB amps, which are much more efficient and thus draw much less current per watt of ouput. IMO, some sound better than others. I'm testing some out now...
In the hypothetical situation that you were putting this system or an even beefier one into a 1-Series - and the lights did dim, would you consider installing a capacitor to compensate for the stress on the battery? The reason I ask is that I've heard mixed opinions on using capacitors in car systems.

Also, when connecting these amplifiers directly to the battery, isn't the alternator bypassed to the extent that the only stress on it would be the duty to re-charge the battery?

Just as a side note: In my first system (a 1996 Saab 900) where I used a Memphis Belle amp driving a single sub a 1 Ohm (1.1KW), I did have dimming issues at the high volumes when I used a sealed sub-box. When I ported it, there was much less stress on the electrical system and the dimming went away.
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      03-09-2010, 08:21 PM   #92
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very nice ill def subscribe to this when i do this in the future
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      03-09-2010, 09:14 PM   #93
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Quote:
Originally Posted by DeFKnoL View Post
In the hypothetical situation that you were putting this system or an even beefier one into a 1-Series - and the lights did dim, would you consider installing a capacitor to compensate for the stress on the battery? The reason I ask is that I've heard mixed opinions on using capacitors in car systems.

Also, when connecting these amplifiers directly to the battery, isn't the alternator bypassed to the extent that the only stress on it would be the duty to re-charge the battery?

Just as a side note: In my first system (a 1996 Saab 900) where I used a Memphis Belle amp driving a single sub a 1 Ohm (1.1KW), I did have dimming issues at the high volumes when I used a sealed sub-box. When I ported it, there was much less stress on the electrical system and the dimming went away.
I actually see it the other way round: When the car is running, everything in the car runs off the alternator output. It needs to charge the battery and power everything else. If we had Hondas, this would be hard. We don't - our alternators are pretty strong. Just because the amplifiers are connected to the battery physically doesn't mean the alternator isn't powering them.

If I did have that kind of problem, I would probably look at upgrading the alternator feed cable under the car before I looked at a capacitor. I'm not a big fan of caps. But again, if I were designing a system which I thought might have such a problem, I'd take that into account from step one.

A sealed box requires more power the lower notes it plays, in a pretty linear fashion. A vented box actually draws progressively less power as you approach the vent tuning frequency, the impedance is climbing and the amp can't drive more power into a higher impedance. So at the tuning frequency, the amp puts out very little power.
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      03-11-2010, 09:34 AM   #94
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Quote:
Originally Posted by VP Electricity View Post
I actually see it the other way round: When the car is running, everything in the car runs off the alternator output. It needs to charge the battery and power everything else. If we had Hondas, this would be hard. We don't - our alternators are pretty strong. Just because the amplifiers are connected to the battery physically doesn't mean the alternator isn't powering them.
To clarify my view of it, we connect amps to the battery because it can handle the direct load better - otherwise we would connect directly to the alternator to power the amp. With the amp draining the battery, the stress is removed from the alternator and then the alternator re-charges the battery at its own pace. If the battery were totally drained from the amp, then the amp would attempt to current pull current from the alternator - which would put a bigger stress on it than just to re-charge the battery. This is not to say that the alternator has no stress, just that it is less than the load that is put on the battery.

I lnow we are getting down to details that probably don't matter very much, but is there anything wrong with my reasoning?

Thanks.
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      03-11-2010, 09:55 AM   #95
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Quote:
Originally Posted by DeFKnoL View Post
...but is there anything wrong with my reasoning?
I was being too polite and indirect before. You're actually completely incorrect, I just softpedaled it too much

The battery is just another load on the alternator.

Read this:

http://www.bcae1.com/charging.htm
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      03-11-2010, 10:30 AM   #96
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Quote:
Originally Posted by VP Electricity View Post
I was being too polite and indirect before. You're actually completely incorrect, I just softpedaled it too much

The battery is just another load on the alternator.

Read this:

http://www.bcae1.com/charging.htm
Thanks, I like direct better - especially with the accompanying explanation .


On another subtopic, I didn't notice if you screwed down the amps. How are you fastening them down so keep them in place? Is there a special approach to that - or is it just to drill the holes into the plastic and screw them down?
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      03-11-2010, 10:33 AM   #97
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The two in the well are gravity-loaded,but the 650 sandwiches them down tightly. The 650 is bolted to a panel which is held down with brackets which tie to factory bolts on each side of the tub.

You can see them in this pic:

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      03-11-2010, 10:51 AM   #98
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Quote:
Originally Posted by DeFKnoL View Post
To clarify my view of it, we connect amps to the battery because it can handle the direct load better - otherwise we would connect directly to the alternator to power the amp. With the amp draining the battery, the stress is removed from the alternator and then the alternator re-charges the battery at its own pace. If the battery were totally drained from the amp, then the amp would attempt to current pull current from the alternator - which would put a bigger stress on it than just to re-charge the battery. This is not to say that the alternator has no stress, just that it is less than the load that is put on the battery.

I lnow we are getting down to details that probably don't matter very much, but is there anything wrong with my reasoning?

Thanks.
We connect to the battery because it's convenient and it smooths the current delivery. Also, you can't connect directly to the alternator because the alternator outputs AC so the earliest in the chain you'd be able to connect would be after the regulator on an externally regulated alternator. And then we're back to the issue of convenience. Have you tried getting to your alternator to make a connection? We're not talking about a late 80s S-10. Anything made after the mid 90s is typically a PITA to get to the alternator let alone finnagle a new connection to.
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      03-11-2010, 10:52 AM   #99
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Can you imagine a Big 3 in our cars?
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      03-11-2010, 11:10 AM   #100
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Quote:
Originally Posted by VP Electricity View Post
Can you imagine a Big 3 in our cars?
I tried looking into doing it when I had my Audi. It took me 30 seconds of looking in the engine bay for me to decide it so wasn't worth the effort I never really looked for the alternator in this car yet but I can't imgine it would be any better.
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      03-18-2010, 02:42 PM   #101
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Hey Ken,

Random question of the week, have you had that tub out of an E90 335i or e90 M3? I don't have them in my drubby mitts yet but I'm going to do a 650.6 and 1000.4 and having dual mufflers I don't have that well that you do. Bing and I were spitballin' and we're thinking we can get them both in there if we go back to back on them. If not, I was thinking that with that tub out and those "extrusions" that the nuts screw down on and the angled corners at the front out of the way they should fit fine once I come up with a mounting scheme.

Thoughts?

Thanks Ken,

Paul
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      03-18-2010, 03:57 PM   #102
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Originally Posted by quality_sound View Post
Hey Ken,

Random question of the week, have you had that tub out of an E90 335i or e90 M3? I don't have them in my drubby mitts yet but I'm going to do a 650.6 and 1000.4 and having dual mufflers I don't have that well that you do. Bing and I were spitballin' and we're thinking we can get them both in there if we go back to back on them. If not, I was thinking that with that tub out and those "extrusions" that the nuts screw down on and the angled corners at the front out of the way they should fit fine once I come up with a mounting scheme.

Thoughts?

Thanks Ken,

Paul
I'm running into the same issue. I can fit 2 long amps in there with a little bit of shaving in places, but there won't be room for anything else. I was going to take the tub out until I found that I would have to drop the muffler to get to the bottom screws. Also, the bottom screws are holding on the heat shield under the car. Anyway, it is either do some cutting on the tub or one of the amps and well, the tub costs way less than the either amp. As long as I don't compromise the heat shield, I should be fine.
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      03-19-2010, 06:59 AM   #103
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Damn, I was hoping it was easier than that. I'm really just curious if there's enough space wih the tub out to justify doing it. If not I'll break out the dremel and trim the tub and be done with it.
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      03-22-2010, 09:23 AM   #104
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Would like to know if there is a problem with connecting the power cable with a ring terminal to the battery's postive treminal, instead of doing what VP did with the distributor block?
I have a 1 series, with focal 100krs, sws8, and a 12" dd sub, powered by clarion 4x90 and 1x1500 w amps. It is probably not producing sq as you would call it as the bass is overpowering.
Sometimes, when I crank it up, the whole thing would stop playing for a split second, and then it is fine again. Is that because the current draw is too much? It doesn't always do that at high volume, just intermittently.
Thanks for helping.
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      03-22-2010, 09:33 AM   #105
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Quote:
Originally Posted by bmw135fan View Post
Would like to know if there is a problem with connecting the power cable with a ring terminal to the battery's postive treminal, instead of doing what VP did with the distributor block?
I have a 1 series, with focal 100krs, sws8, and a 12" dd sub, powered by clarion 4x90 and 1x1500 w amps. It is probably not producing sq as you would call it as the bass is overpowering.
Sometimes, when I crank it up, the whole thing would stop playing for a split second, and then it is fine again. Is that because the current draw is too much? It doesn't always do that at high volume, just intermittently.
Thanks for helping.
Are you using the OEM HU? If so, any LOC's?
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      03-22-2010, 09:47 AM   #106
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Yes, oem hu. No LOC as the amps take speaker level inputs.
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      03-22-2010, 09:54 AM   #107
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Oh, whenever it cuts out it seems to coincide with when I am playing songs from a USB drive. Doesn't seem to do it with radio, and only at loud volume, but not all the time. I did the install myself, so the quality of work might be a bit suspect.
Sorry to hijack the thread, I thought I might ask here as the topics of power cable and current draw were brought up.

Last edited by Brissie; 03-22-2010 at 09:59 AM..
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      05-08-2010, 08:14 AM   #108
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to user mathematics with dynaudio setup

Perhaps a little unrelated, but directed to user 'mathematics', I am currently running a dynaudio 222 setup with an aliante neo sub with huge power from genny DMX amps, but still find the midbass lacking. I see that in addition to this driver, you also have the 8 inch mw172 dynaudio woofers in your actice setup - my question is, is the midbass strong/punchy with the mw172, and do you think the combination of mw152/md102/mw172 would work well if I were to go for a focal branded sub in the future?

Cheers,
Dave.
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      05-08-2010, 09:48 AM   #109
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Quote:
Originally Posted by dc7777777 View Post
Perhaps a little unrelated, but directed to user 'mathematics', I am currently running a dynaudio 222 setup with an aliante neo sub with huge power from genny DMX amps, but still find the midbass lacking. I see that in addition to this driver, you also have the 8 inch mw172 dynaudio woofers in your actice setup - my question is, is the midbass strong/punchy with the mw172, and do you think the combination of mw152/md102/mw172 would work well if I were to go for a focal branded sub in the future?

Cheers,
Dave.
Yeah, that's pretty off-topic, but since it's my thread...

How low are you playing the MW152? It's a great driver, but you're gonna run low on midbass, and you would indeed do better with *something* under the seats. But use a crossover point on the 150 of no higher than 150, and a low pass to the woofer ditto.
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      05-08-2010, 02:55 PM   #110
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And to piggyback, what midbasses and midranges yuo run has absolutely nothing to do with what sub you run later.
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