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BMW 3-Series (E90 E92) Forum
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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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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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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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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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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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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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03-11-2010, 11:10 AM | #100 |
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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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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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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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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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