Hey all-

I know this isn't really an Empeg specific question, but I'm pressed for time and this board has the fasted turnaround times I've seen, so here's my goes...

I recently had a completely new sound system installed with my Empeg - Speakers, Amp, etc. The installer was supposed to run 4 gauge wire to the amp (mounted in my trunk) because I was thinking of adding a sub later. Well, he forgot and only ran 8 gauge to the trunk, and I've decided to add a sub, specifically the Infinity Basslink. The amp I have is the Alpine MRV-407, and it's driving four plain Infinity speakers. I'm wondering if I'd be OK wiring the 8 gauge power wire to a distribution block and running both the Sub and Amp off of it since the Sub is fairly power efficient (it has a Class D amp) and the Amp is driving fairly "lightweight" (4" - 5 1/2") speakers.

The reason this is pressing is that I'm driving out to a wedding that's 5 hours away this Thursday, and I'd really like to get the sub installed before then.

Thanks for any help you can give,
Adam

"It's not that I'm lazy, it's that I just don't care..."
-office space

Most "recommended" power wiring, even for high-end amplifiers, is usually overkill. I'm sure the 8ga will be more than enough. As long as you've got proper fuses at the important points, you won't run the risk of equipment damage.

Doug, chime in here and give us your power-wire wisdom.

___________
Tony Fabris

Thanks for the input Tony .

Oh yeah, that reminds me, the recommended gauges are 8 for the amp and 12 for the sub/amp.

-Adam

"It's not that I'm lazy, it's that I just don't care..."
-office space

Oh yeah, that reminds me, the recommended gauges are 8 for the amp and 12 for the sub/amp.

No problem, then.

___________
Tony Fabris

Yea, with recommended gauges of 8 for the Alpine amp and 12 for the Sub amp I didn't think there would be a problem, but since I'm going to be supplying both devices from a single 8 gauge wire from the battery I wanted to be sure that I wasn't going to be sacrificing sound quality (especially since I, like many other empeg owners I'm sure, have a sunk a hefty sum of money into my car stereo now. I swear, owning an empeg has the same effect on your wallet as dating an attractive girl .)

Alright, I think I'm going to go ahead and install the sub, but if anyone thinks that I should run 4 gauge wire back there first please let me know...

-Adam

"It's not that I'm lazy, it's that I just don't care..."
-office space

Doug, chime in here and give us your power-wire wisdom.


You are right on the ragged edge of adequate wire size.

It isn't a question of how many speakers and what size speakers you are driving, but how many watts of power your amplifier can put out, the efficiency of the amplifier, and the length of the wire run to the amplifier.

A worst case scenario might be that you are running your amp at max output -- 640 watts peak (320Wx2 bridged 4-ohm) with a 15 foot wire run, and assuming that your class D amp is running at 80% efficiency. This would put you over the maximum acceptable 1/2 volt drop through the wire run. The most you could run would be about 580 watts under those circumstances (that would give you a .49 volt drop :-)

However, you aren't likely to be running your amp at its max output, but at considerably less than that. But to negate that to some extent, amplifier efficiency drops as the gain levels are reduced.

For a bit of education on this topic, go here. This is beyond question the best website I have ever seen about car (and to an extent, home) audio. It is well worth spending 20--30 hours there. I have done so, and have learned a LOT. (Go to the bottom of the page linked above, and follow the link you find there to the home page of the site.)

Anyway, it is not likely that your car will erupt in a ball of flame and shrapnel because you are using the 8-gage wire. But 6-gage would have been better. 4-gage perhaps a bit of overkill, but always better too much wire than not enough!

tanstaafl..

"There Ain't No Such Thing As A Free Lunch"

Hey,
My 2 cents.
Doug and Tony are right and very informative. I would like to make it perfectly clear that your current wire selection is okay. You shouldn't walk away wishing you had the other wire because it won't make any difference to YOU in YOUR system. If you listen to your system and are happy with the sound, Great! If you are unhappy, changing the wire won't make it better. There are so many factors that go into good sound that you shouldn't stress over that wire. Doug explained the wire calculations well but you must remember that he is at a more professional level. Your amp probably uses a DC to DC converter and at MAX volume you could end up with output clipping if you don't have the proper voltage. It may also affect filter characteristics if this stage is not regulated well. These are problems that you will probably never run in to.

What I'm trying to say is take the money you save on that outrageously priced 4 gauge wire, get a cold soda, some new music and enjoy your awsome new system!

Alex Lear

Tony, Doug, Alex -

Thank guys for the help. Once again, the Empeg board has exceded my expectations. Also, a big thank you Doug for that web site, I'm sure I'll burn a lot of time there while at work...uh, free time, of course...heh heh....

-Adam

"It's not that I'm lazy, it's that I just don't care..."
-office space

Well, he forgot and only ran 8 gauge to the trunk, and I've decided to add a sub, specifically the Infinity Basslink

After reading this I went to the Infinity site and looked at the sub. After rolling my tounge back in my mouth I found a retailer in the UK who sells them and bought one. I installed it last Tuesday and all I can say is

WOW

It is truly awesome being able to feel the beat of the music. I am absolutely amazed at the difference it makes. I was sitting at some traffic lights yesterday and I could see the rev counter dipping in time to "Block Rockin' Beats" by the Chemical Brothers. Fantastic.

Kudo's to Adam for bringing this to my attention.

ChrisTall
That really is my name!

Hmm
If you're pulling that many amps that your revs dip on heavy bass, you should really look into a bigger battery and a stiffening capacitor and probably larger alternator.
My lights dim a little at idle and I thingk I need a cap and tend to go through a battery every 2 years or so.

You might find that your system will kill batteries pretty quickly if you are getting that much drain.

Serious bass is fun though isn't it!!



Murray 06000047
Just increasing my post count

Hey guys-

Just thought I'd give you all an update. I installed the infinity sub in the trunk of my car with just the 8 gauge wire running back there, and it has worked wonderfully. No problems at all.

I'd definitely recommend the Basslink to anyone who doen't have a sub already (I'm glad you like it Chris). It's a cheap (~$230), easy way to improve your stereo. Seriously, if you don't have a sub in your car you don't know what you're missing. Thanks again for you help everyone, your nepenthean (ref. "The Raven" ) advice was much appreciated.

-Adam

"It's not that I'm lazy, it's that I just don't care..."
-office space