Car audio questions

[JHZR2]

Hello,

I have a few questions regarding car audio...

First, I will be upgrading the speakers in my 1981 MB 240D. The PO took GREAT care of it, and the car is lik new, except that he took out the original headunit for a CD player. No big deal, I have a nice refurbished Becker headunit (original look) that even has a hidden MP3 playr input. OK, great, so I might as well put in some better speakers and whatnot then. Some of the speaker harnesses are a bit chopped though, so Ill have to do some soldering and adjustment.

I figure I might as well install a 4-channel amp while at it. Long story short, some amps have line output converters installed, others don't. This is a job that I want to "do right", but I dont care to spend $1000 on it either. So... Is there really a big difference in quality between using speaker level inputs into an amp (on a correct, speaker level input) vs. buying a LOC and wiring that in so that I then have line level inputs to the amp? The only differences I can see are perhaps a bit better circuitry and an additional ground. Can it make a very large difference?

Obviously speaker level in is easier. No wire runs are very long. However, I do not want to regret my installation chouce because of a hum, whine, clipping or any other sound quality consideration. Id imagine things would be about the same with either layout, but Id appreciate advice.

Second, if Im not playing loud, not pushing lots of power, and only driving four speakers, either at 4 ohm or 8 ohm, do I need to put a capacitor inline? Is it best practice, even if Im only looking at, say, 40W RMS per channel? Does it help protect the alternator or other electronic circuitry? Does it help the amp to start up faster, I can understand helping with transient loads, but I dont feel that the way I use the radio/amp, that I have anything very severe. Any other good reason to have one?

Thanks in advance,

JMH

 

[Gary Allan]

I'm sure they've managed to neutralize it, but I would think that speaker level inputs would have more noise to them. I considered it a "practical adaptation for ease of installation" and not the preferred modality of conducting the input signal.

 

[Barkleymut]

Using RCA patch cables are the best way to transfer the audio from a headunit to an amp. Speaker level isn't bad and you likely will not notice too much of a difference. A 4 channel amp 4x40watts RMS will give you pretty good sound with some nice aftermarket speakers. I suggest going to a local C.City or BBuy for speakers and listening to what sounds good to you and make sure they can handle the watts you are pushing to them. Go with an amp that you recognize the name on (sony, pioneer, jensen, mtx, alpine, kenwood). If you can run new speaker wire from the amp to the speakers it can only help as old speaker wires may have some of the insulation worn off etc.

The most likely problem you will run into is not grounding the head unit or amp well enough which will produce a very noticeable hum.

Of course you can always go with a 2 channel 65watt amp and push 2 6x9's in the rear and it will sound really good also. I don't know what size speaker is standard in your rear deck.

PM me if you have any specific ?'s - I used to really be into car audio but have been out of the loop for a while, but things have only changed so much.

 

[Barkleymut]

and no you do not need a capacitor.

If you want some great advice call Crutchfield, you can check them out at crutchfield.com they always have the best customer service department.

 

[BuickGN]

I know it's apples to oranges but with my TL I'm not running a cap and I have 2 12W6s running off of an old Infinity digital Beta 300 1,000 watts rms and a 6-channel JL amp for the mids and highs. I don't push it anywhere near it's potential because I'm more into SQ than the entire neighborhood hearing me.

Pretty much anything from Circuit City and most local chain stores are not going to cut it for you if very high sound quality is what you're after. I didn't do my research and have upgraded twice on the mids and highs. Luckily I got it right the first time on the subs. If you want very good quality with a good punch, you can't beat a JL audio W6 or IDMax. For mids and highs, Focals, Beymas, MB Quart, etc are nice.

For what it's worth, I originally fed my sub amp through a LOC from the stock sub wire. After about 6 months I tried running the stock sub wires straight into the high input of the amp and the sound quality was much better. Unfortunately I have to use LOCs for the other amp but haven't run into any hissing or alternator whine so far.

 

[bretfraz]

Going low level out from a head unit to an amp is the best way in terms of sound quality and much better than taking an amplified signal, deamplifying it then reamplifying it. But, in your application, will you notice a difference? Maybe not depending on speaker choice and placement. On the highway in an old diesel Benz with some decent but not top of the line speakers, it may be a moot point.

An LOC might make a diff but it depends on installation quality. A decent LOC will run you about $20-30, so it ain't gonna break the bank. An LOC would give you a trigger wire to auto-power on the amp when you power on the stereo. Also, an LOC may help with the power-on "pop" you get from the speakers. This is an area where a conversation with an experienced installer would help. For the price I'd seriously consider one.

I don't think a cap will make much diff in a 4x40W system.

 

[Patman]

Definitely no need for a cap in this situation, the main time you would run a cap would be if you're running a much bigger amp with subwoofers. I've got a small capacitor for the system in my Corvette, but I'm also running a 12" subwoofer driven by a 670 watt Rockford Fosgate amp, and even with the small cap the lights will go slightly dim every time the stereo is cranked up and the bass notes hit hard.

I would recommend using RCA cables for the amps though, because it would be even worse to get the entire system all wired up and then find that you need to take it apart again and rerun some of the wiring. When we built my system it took us at least 20 hours worth of work because we had to take so much of the car apart, but now that it's done I'll never need to do it again even if I decide to change some of the components later on.

 

[cven]

IMO You should always buy a bigger amp than what you need. A small amp will quickly distort and this is what kills speakers. A large amp will provide CLEAN power and this will not only sound better but will help your speakers last. A 30 watt amp cranked up will destroy a speaker rated for 150 watts.

 

[mcrn]

JH I have had a 240 and put in a near sound quality winning system. I just want you to know you will not get a very good sound just by replacing those speakers. TRUST ME! I don't know what kind of quality you want. Feel free to PM me if you are interested. The 4 in speakers in the dash are just not up to doing anything with no room behind them.

 

[mcrn]

I also have suggestions for you if you are not interested in a high quality system. The Germans back then just did not care at all about sound. Its hard enough just to get enough sound to over come that engine noise! Great car though. They are tanks. I still miss mine.

 

[TylerL]

Millionbuy.com sells MB Quart speakers(made in Germany) and amps for fairly cheap. POWER ACOUSTIK amps are a good value, low price with good quality.

I used RCA outputs, but my dad had LOCs in his Civic with no ill effects.

 

[JHZR2]

My car uses an original, early 1980s becker radio - anything else would look ridiculous... therefore no RCAs.

I actually already have MB quart speakers to use in the car. Ive installed some in my BMW, and I like them so Im using the same in the MB. Its merely the amp between the fader (post radio), required to take the 2-channel from the HU to 4 channels, and the speakers.

The thinking is this - an amp with high level input likely has an LOC in it already. If I buy an LOC with 4-channels, or two, 2-channel LOCs, then I have one or two extra grounds to deal with... though I MAY have better electronics. Other than that, Im not sure if there is a benefit...

So thats what I really have to deal with any my curiosity...

Thanks,

JMH