Experts: I need your Blessing

Wolfmag

Since I already went over my budget, and since my Live-in Girl Friend just dumped my pathetic **** a few days ago. I've decided to distract myself and actually bought an amp instead of trying to maximize the sound from my polk MMC650s via deck power. This Car Audio stuff is the only thing that's keeping me sane right now.

Come to think of it, I probably should have waited to get you guys's approval first before ordering (brain ****)...

Anyways, I've been lookin' comparing, reading forums, checking prices and everyone keep saying the best bang/buck amps are made by USacoustics, Hifonics, JBL, RF, and a couple others I can't remember with looking up. My budget was around 200 bucks. One of my biggest complaints is that my Sub/amp sounds a little sloppy to me. I want it to be tighter, quicker but still make it beat the **** out of me. I tried things people suggested, like reopening the Sub Box and taking out all the fiberfill since it "slows it down". Still, it just doesn't quite seem as tight as my old MTX sub Thunder 6000.

I soon learned that is probably because of my Amp for two reasons. 1, it being only around 150 watts which is too little to move my Infinity Kappa Perfect 12.1. 2, It's Damping & Slew is only rated at >200. I know it's not the Box being to large because I had made sure I bought one at exactly 1.0 cubic feet which is what Infinity recomended.

And so the search went on for the best, budget amp that had a decent Damping/slew rating. It has to support Tri-Mode as I want to power my two fronts and my rear sub - all with one amp. The problem is, with those Amps I listed above, either their Damping/Slew were horrible (many were worse then my lil MTX Thunder 152 amp!) most of them don't even list it!!! Especially the JBL which seem to be the most popular/recommended. Even when I went to the Manufacture's Website and looked up Manuals, Specs, etc. Nothing. There must be a reason why they don't list it. Kinda shady. The USacoustics definitely looked like the best bargin, but it's Damping was one of the worst at >100!!! Ugh...

I knew that I'd regret not researching farther and spending an extra 100 bucks for an amp I could be proud of. An amp I wouldn't mind transferring to my next car. I tried to limit my selection to only what Etronics had available, since I trust them, and it seemed alot to me anyways...

I finally settled on this:

***SoundStream VGA320.4***
Output (watts): RMS @ 4 Ohms 80 x 4
RMS @ 2 Ohms 160 x 4
RMS Bridged @ 4 Ohms 320 x 2
T.H.D.: <0.02%
Signal to Noise Ratio: >115dB
Damping Factor: >500
Frequency Response: 10Hz - 50kHz
Input Sensitivity (V) : 0.15 - 12.0
Crossover Slope: 12dB
Crossover Frequency 30Hz - 4kHz
Dimensions: 11.2 x 2.6 x 13.8

>RUBI™ (Rapid-Use Branched Impulse) power supply
>STACT™ (Stabilized Apex Current Topology)-- Reduces power supply stress by 50%
>Fully regulated MOSFET power supply
>Trident™ amplifier protection
>Ultra-Low ESR Capacitance Bank-- ensures rapid power delivery for dynamic peaks
>Hawkins Bass Control
>Intelligent Distress Indicator-- gives visual indication of amplifier protection status
>Tri-mode operation
>Harmonic Bass Alignment-- produces tighter, more accurate bass
>Triple Darlington Output Circuitry
>Bias Input Protection
>Rail Stabilization Protection Circuitry
>Bi-linear selectable two-way crossovers for amplifier and line outputs
>Continuously Variable High and Low Pass Crossovers
>Balanced Line Inputs for the Highest level of Noise Rejection
>Vortex Induction Fan
>Platinum RCA Inputs and Outputs
>Platinum 4-gauge Power Connectors

---

Now I don't know what all the stuff does on the Feature List but damn, look at those STATS!! 8)

>500 Damping! Yay!

The amp cost me 314 bucks plus 15 dollars shipping & it's on its way. The retail on that amp is ridiculous!

Did I make a decent choice fellas - is there any thing I should be aware of? Price wise, it seemed to have the best stats for the money. Will it work as I intend? According to it's Wattage output, I should be able to power my two front MMC650s with 80 watts each @ 4 ohms and the rear sub, bridged at 320 watts @ 4 ohms right?

I hope I made the right decision, I suppose I could always return it if you guys throw up some major red flags. I'd have to eat the shipping cost (both ways) but, I do trust you guys enough to do it if needed.

Thanks in Advance.

-K

Jstas

Actually, that looks like a pretty nice amp. As long as it has the power you need and fits in your car nicely, it looks like a good amp.

Soundstream gained fame in the lat 80's, early 90's with some really efficient power supplies. They were one of the first companies to fully exploit the D-class amps when they came out. For a while, they were the power amps, known for insane levels of clean power. In the mid-late 90's, they had started seeing quality control issues and the amps still made power but they were sporadic at best in quality and specification accuracy.

They seem to have turned things around and are putting out nice equipment again. Especially with thier Human Reign series and the power that they make. Soundstream is not a bad choice at all. From the specs you posted, it looks like a good buy. The sub cost 314 bucks? It's an Infinity? Why so much? How much did you pay for the amp?

Wolfmag

Whoops, I meant the Amp cost 314 bucks... (i'll go edit that)

The Sub cost me 137 dollars... all at Etronics.


Thanks Jstas!

I was really worried there since this amp is hardly ever talked about on forums. I guess SoundStream lost popularity since it's quality issues. I'll make sure to register my warranty then.

Jstas

Dude, not everybody knows everything. It's not talked about because Soundstream is weak in the market place. It used to be Circuit City's premiere line but lost sales when quality issues cropped up. Just because it isn't talked about doesn't mean it isn't any good. I don't know about the rest but I don't scour the Internet looking for audio equipment. Just because it isn't talked about doesn't mean it isn't any good just that nobody knows about it. If you see something, ask about it and everyone here will be sure to discuss it.

Wolfmag

I sure will. I just wanted to do some pre-emptive research to try to educate myself so I don't ask the 'annoying' questions. At least I hope not.

Anyways, my only other concern now would be if my old 1990 Nissan 240sx can handle the new Wattage pull from this new amp. My lights don't dim right now, but like i said, I have this cute little mtx amp which only pulls 170 watts at best. If it does become a problem, I probably just raised the cost of this project exponentially. =/

So far I’m at:
- $180 for HU (Sony MP40 – I know, I know – Sony Suxors, it was my first purchase and I didn’t learn that until it was too late. I just wanted to be able to play mp3s)
- $170 for the Front Speakers, Polk MMC650
- $60 for the Rear Speakers, Alpine Sps-170a
- $137 for the Kappa Perfect 12.1
- $60 for the Sub box
- 314 for the SoundStream Amp

Total: $921 :eek:

Jesus!! Car Audio is expensive. That doesn’t even include Tax and shipping for everything. Plus I gotta get the amp installed. You gotta have a definite love for music to spend this kinda money and this would probably be considered pretty weak by a lot of people.

Thanks for the replies.

Jstas

What is teh fuse rating on the amp? Find that out and compare it to the fuse rating on your current amp(s). If they are close, within a 10-15 amp draw difference, you'll be fine. If it is doubled or more you may have an issue. I think you will be OK though.

$921? Is that all?

I have over $3500 invested in car audio. My truck has about $2800 in it alone. I only put down about $1800-2000 to pay for any of it though. My girlfriend's car has about $1600 but I only paid about $1020 for all of the stuff in her car.

MTXMAN

Soundstream's a great company, just not well known. When someone comes to me for advice they're among the first brands I look at to see if there's an amp that performs for the guys price range.

sntnsupermen131

with all the stuff ive broke...$921 is probably pretty weak...i used to keep count of all the purchases i made...when it got over 3k i quit...lol
but now im interested...im going to get all my receipts and add them up...
i added everything up...total is $4,425.32
that is WAY too much for what i have in it right now
in reality...ive probably almost spent $4,700 with odds and ends
if i could go back and do it again...i could do everything for probably less than 3K
a lot of it is is i blew an amp...had to buy more...$540 right there...plus i rewired the whole truck...which i probably wouldntve done if i hadnt blown it...and thats another $400
and before i got the radio i have now...i bought one for $150 used from a friend
man...i didnt think ive spent that much...i dont have much to show for a $4.5K system...
-Cody

Wolfmag

"What is teh fuse rating on the amp? Find that out and compare it to the fuse rating on your current amp(s). If they are close, within a 10-15 amp draw difference, you'll be fine. If it is doubled or more you may have an issue. I think you will be OK though."

Honestly, for the life of me, I can't find where they list the fuse rating on that new SoundStream Amp. The companies website doesn't list it and it hasn't arrived yet. My current MTX amp fuse says 30 on it. I imagine it would probably be double or more then that since this amp, according to it's specs, could potentially run two channels bridged at 320 watts @ 4 ohms. Or does it not work like that?

Also, some what related, can someone recommend an Amp kit that would be appropriate for this amp? I'm kinda confused by the advertisements of amp kits saying they are made for X amount of watts. Should I detirmine the amp kit by the highest possible rate this amp can run (2x320watts)? So should I look for an Amp kit that says 600 watts? I suppose it's also important that it specifies the length of the neccessary wires to be able to reach the back of my trunk since I'm unsure this thing will even fit under my seat.

Any input on this would be much appreciated.

Thanks.

-k

C-Man

A general rule for class AB amps is the fuse rating will come close to matching the output power... like if you have an amp that will put out 300 watts rms bridged, the fuse will be somewhere between 25-35 amps. Of course with a good monoblock class D amp, like the Hifonics Brutus 1500, the fuse rating is only 80 amps while the amp puts out 1500 watts... but they are designed to be much more efficient than the class AB.

So if the RMS on this amp is 320 X 2 @ 4 ohm it's probably gonna have 2 30 amp fuses.

C-Man

I'm sorry, by matching I mean 1 amp per 10 watts.

Wolfmag

I see well hmm... I may be rolling in to an alternator issue then. Oh boy, I hope not. What about Capacitors. Will they help? I'd gladly first get one of those before having have my Alternator replaced... if it will solve the issue.

Also, what about the Amp kit. If it has two 30 amp fuses, should I get one that's rated at 600 watts or higher? If I get one that's rated too high, wouldn't that just mean the fuse it comes with would to large meaning it won't pop when it should?

Would this be ok? I've heard Rockwood suqs but, does it matter for Amp kits?

***Rockwood POWERKIT-9 1800 Watts Amplifier Hookup Kit***

1800 Watts / 4 Gauge
High Power Transfer
Oxygen Free Copper
Battery Clamp
In-Line Fuseholder
17 ft Power Cable 4 Gauge
3 ft Silver Ground Cable 4 Gauge
18 ft Blue Power Cable 8 Gauge
6 ft Silver Ground Cable 8 Gauge
20 ft Speaker Wire 12 Gauge
16 ft Blue Remote Wire
17 ft Twisted Pair RCA Interconnect Audio Cable Right Angle
Battery Terminal Clamp
1 x 4 Gauge in 4 x 8 Gauge Out Distribution Block
1 x 4 Gauge in 2 x 8 Gauge Out Fused Distribution Block
Split Loom Fir Cable Protection
Ring Terminal Installed
Cable Tiles and Accessories

$34.99


Thanks so much for the replies.

-k

C-Man

I don't think you'll run into any alternator problems with a single (let's round up to) 700 watt amp. Most stock alternators are +/- 80 amp and your Soundstream probably won't draw anywhere near the 60 amp fuse ratings suggest, especially running the front channels at 4 ohm.

I wouldn't do the Rockwood stuff. Here's a link for much better quality product (per Cody) and it's about the same price (Actually a little cheaper).

http://www.knukonceptz.com/detail.asp?product_id=KOLAK4

It's got most of what the Rockwood has and I can be positive that it's much better quality. And maybe I live under a rock, but the RCA's have a built in remote lead... that sounds pimp to me. No more wire ties... lol.

Wolfmag

Thanks C-Man! Seriously. I wish I would have consulted you... someone!... before i bought my HU. What a difference it makes.

Thanks again.

-k

sntnsupermen131

knukonceptz is really great for power wire...anything else...i dunno
im very picky about rca cables and if the kit costs $30 and it includes rca's i just dont know
but i think it will fit your application fine...if not...get some streetwire 3.0s and chances are youll never have any type of noise in your lines
just remember to keep any electrical wires for your car separate from any audio wires
keep power wires together
speaker wires together
rcas together....but have everything seperated...know what i mean?
if not, ill try and explain a little better...
-Cody

MTXMAN

you can always look at the streetwires gear at www.mitekfactoryoutlet.com they make some good wirez and patch cables

Wolfmag

So the Amp finally came and I called a local car stereo shop and asked if they could install it RIGHT then. Sure enough, they said yah, no problem.

4 hours later (2 hours of them installing & 2 hours of me tweaking) I'm boomin'!

The immediate change I noticed is that my bass heavy rock music like Static X and KoRn played flawlessly. Previously, that was what my deck powered speakers had the most trouble with. I guess Rap is all highs and super lows so you could "get away with" deck powered speakers and an amped sub.

What amazes me about this new amp is now, not only do my front speakers get loud enough to actually start hurting my ears before distorting, I can have my subwoofer hit harder & cleaner and my internal lights don't dim. Earlier, when I said my lights don't dim, I meant there was no noticeable dimming of my head lights. But when I was playing a bass heavy song, my internal lights would dim with the music. This amp for whatever reason is just more efficient I guess. Cleaner & louder output for less total draw from my alternator. So my worries of needing a bigger alternator is more then just a non-issue, in fact, it *improved* the situation!

Unfortunately, the amp was to big to mount under my seat so I had to have it mounted to my back seat, against the back rest facing the open trunk. Turns out it's better this way anyways since it has tons of controls that I'd never be able to reach without removing my seat (what a pain in the **** that would be). I had the installer use 4 different screw types to mount the amp since I read that some where here I think, that it's another way to discourage/slow down thieves.

The Amp frigin' rocks, what a difference! I was however surprised that I still had to crank up the Bass Boost so high, to make it "hit" hard like I'm used to. I figured since it suposedly is pumping 320 to my Sub, it wouldn't need as much bass boost like my lil MTX did (which pushed only about 170ish). Nevertheless, the end result is pure satisfaction. Unlike the MTX amp, it never seems to distort, even with tons of bass boost.

There is one concern however, is it normal for the amp to get hot? I mean REALLY hot - As in I can't leave my hand on it for longer then a second or two. If not, should I be looking in to some sort of active cooling?

Thanks for reading.

-k

p.s.
Oh, the manual actually states the slew rate. That was something I couldn't find for some reason on the net but figured the damping was a good enough indicator that it should handle a sub cleaner then what I had.

>50 V / uS (it's not really a "u", but a similar looking symbol)

Jstas

Um, about the bass boost thing, have you adjusted your gain properly? On both my Kenwood and my Hifonics, the bass will kick like a mule without any boost at all. Find out what your pre-amp voltage is and then adjust your gain setting to that.

As far as heat goes, yes, it is normal. Especially if you are pushing the amp. Havint high powered amps under seats is a bad idea. They overheat because there isn't enough room to breathe. My Kenwood gets too hot to even try to touch sometimes. That is usually after a dead waking audition of Nickleback or Ozzy or something equally loud and offensive! The Hifonics amp in my girlfriend's car, when she gets done with her rap and dance crap that she ALWAYS plays, the Hifonics will actually have heat ripples coming out of the vents. They aren't really all that bad but I have noticed them a time or two.

Anyway, amps get hot. Any load, if played long enough and at a high enough level, can cause an amp to overheat. Just because your amp is hot doesn't mean it is overheating though. Even my Profile amp gets hot to the touch. On some of my older Kenwood amps, if they were painted and not powder-coated, I'm almost positive they would have melted the paint right off.

Wolfmag

Wow, I see... Ok then, judging by your description, I'll consider its heat behavior normal then, lol. It says it has a thermal shut down protection anyways and it has yet to activate so I assume it's still within normal levels.

"Find out what your pre-amp voltage is and then adjust your gain setting to that. "

Ok, this is the part I don't understand clearly. I have an "idea" of how this works but... here's how I understand it (applied to the project at hand):

I was unable to find out the Pre-amp voltage of my Sony Mp40 outputs on the net (very frustrating), so I eventually called the local shop that installed my amp and asked if they knew. After a short wait, he came back to me and said 2 volts. How he found that out, I have no idea, because not only does the companie's website not list it, my manual doesn't either. =| Either he pulled that number out of his **** and assumed or he had tested it (doubt it).

I have my Sub hooked up to the 3rd & 4th channel in a bridged configuration. My Rear Speakers are still hooked up to the deck. Now this amp says its Input Sensitivity is 0.15-12.0 Volts. It says if I am using a High Volt input, 4 volts RMS or higher, that I need to flip one of the switches on it that says ATT to 'on'. This is, of course, currently off. The strange thing is, if I have it set to Low Pass, and I set the HU to the "middle volume", the point to where my rear speakers are as loud as it can get before distorting, and use that as my point of reference... to get the Sub woofer anywhere *near* the volume I want it to be, I have to *max out* the gain! That... can't be good. However, as soon as I switch it to Full Range, jesus, it's like my amp doubled in power and the subwoofer hits really hard, sorta like what I expected from such an amp. Now I know that's not an option since it can hear voice from it (its amazing how clear it is too, lol) as this will burn out the sub, correct? So the next step was to play around with the dials that become active when in Low Pass mode:

LP dials:
- The LPF: 50hz to 5khz
- Sub Sonic: 10 to 100hz

Hawkins:
- Boost: 0db to 18db
- EQ: 30hz to 100hz

Now I did notice that, similar to setting it to Full Range, the broader the spectrum I set the LPF, the louder it seemingly got (when set to 5hz, it's almost as loud as setting the entire thing to FR). It wasn't until I started messing around with the Boost that it REALLY started to make a difference. With the EQ somewhere around 45hz, I have the boost pretty far up there, around 14db with the Gain set to a bit over 3/4 was I finally able to make my sub meet and exceed my previous subwoofer expectancies.

Is this because my Mp40's prevolt output is trickling out at a miniscule value (less then 2 volts) why I have to do this or am I doing something wrong? There is no seemingly way to set the amp to a "2volt" setting, it simply has an AB switch, one for normal, and one for high volts 4~12. I mean, like I said, overall I am satisfied with the new and improved sound however, I am a bit worried that I'd have to set the gains & Boost so high. Am I correct in my logic that decks that push 4 volts or higher are partially doing the Amps job allowing you to not have to raise the amp gain as much - meaning your making the amp not work as hard? If so, it would seam more important then the Amp's wattage, but for me to find a HU that could push the max amount the Amp allows (12 volts) which would give me *massive* amounts of headroom to WELL exceed my bass requirements without boost if I never needed. At this point, it seems that I *require* a high Bass DB boost to achieve the bass bias as I am used to. Unless of course, I switch it to Full Range, which isn't an option... right?

Thanks so much for your patience.

-k

Jstas

Well, pre-amp voltage, if not a high volatage is usually between 1.2 and 2.5 volts which is low. So I'm guessing your gain is set high enough. I would leave it where it was set.

But judging from the rest of your post, you say performance increases as you ramp the gain up and and push the crossover up teh frequency range. Well, thats bad for two reasons. Number one, you are basically over driving your amplifier. When you push the gain up, you cause the amplifier to react to the signal level on a more sensitive level. That level is set by the gain and the higher the voltage of your pre-amp out, the less sensitive the amp has to be to pick up all the changes in the signal. That is why a 4 volt pre-amp is more desireable than a 1 volt pre-amp out. A 4 volt signal is stronger. It's like hearing the difference between someone standing 10 feet away and whispering or someone standing 10 feet away and shouting. It is easier to understand that shouter than it is that whisperer.

So, think of the wire as a carboard tube. You are on one end and the whisperer is on the other. You hold your ear up to the tube as the whisperer speaks into the other end. You can hear him ok but somethings are hard to hear. Now, put the shouter there. You can hear him just fine, infact, too fine. His signal is overpowering the tube and your ear but you are still processing it. It probably hurts your ear too. While your ear won't necessarily distort, that discomfort you feel and makes you want to pull your ear away is basically the same thing.

Now that you have a general idea, here it is simply. When you turn up the gain, you increase the sensitivity of the amplifier. If your input voltage to the amplifier is at 2 volts and you set your gain level for .5 volts, it's like putting that whisperer at the end of the tube. Sure the stereo sounds more powerful and sometimes it is OK to push it a little harder. It won't hurt things. The higher up that scale you go though, the worse problems can get. You also get signal clipping, not just amplifier clipping and clipping is serious bad news.

Now, please do not push that sub crossover about 200 Hz at the very most. Infact, I would not go beyond 120 Hz and most systems are happy between 80 and 100 Hz. Anything more than that on a sub and you will cause pre-mature failure that is usually catastrophic and needs a complete rebuild of the speaker to fix. In addition to that, passing too much of a frequency range to the speaker can cause the magnet and voice coil to build up an excessive amount of heat. As it heats up, a speaker's impedance changes causing the amplifier to work harder and harder to play music. Heat is bad as I said before. Heat in a speaker will end up blowing the speaker. Bad news. So please keep your crossovers set properly. I know it sounds good but it reall is bad.


As far as your volume levels, your problem is the rear speakers. I saw this coming actually. The deck is woefully low powered compared to the amp and it just cannot keep up. You cannot turn the system up loud enough because the head unit cannot support the volume levels that the amp can. The subs are not going to play loudly at such a low level because stereos are supposed to be balanced and subs shouldn't really over-power the other speakers, they should compliment them. You may want to look into gettinjg a seperate sub amp and wiring the rear speakers into the 4 channel amp. You can pick up a cheap stereo amp and bridge it to a mono-channel. Profile California series amps are dirt cheap and relatively efficient. They make good solid power and are good choices for cheap sub power. Other than that, the only thing I can say to do is pull those speaker wires off of the rear speakers and listen to it that way.

PoweredByDodge

I bless you in the name of the father, the son, and the holy ghost... now go in peace my son, and leave 20 bucks at the door.

C-Man

Another option is to take the front channels of that amp and run all 4 of your interior speakers off of them in a 2 ohm stereo load. You'll double the output power of the front channels making it quite a bit louder with little or no distortion. Of course if you're already having heat problems it may cause the amp to actually overheat running the low load.

Anywho, you might wanna give that a try, that way you'll be able to turn you gain down some and turn the hu volume up more.

Wolfmag

Ah...Thanks for the input sensitivity analogy. That makes it much clearer and I understand the problem now.

So... Potentially, I *should* be able to drive the deck harder before reaching its distortion point bring up the pre-amp voltage. My Amp would then “hear” it clearer BUT my deck driven rear speaker would be horribly distorted by then… I have a small car, and although it would be too detrimental to the overall sound if I lost my rear speakers, I do want some rear fill.

C-man's suggestion sounds damn tempting but those rear speakers are more sensitive and handle half the RMS as the front. So not only would the rear speakers become louder then my front, they would also most likely blow, lol. Also, I've seen people say you *shouldn't* run your highs at 2 ohms. Not sure why... messes up the SQ? Plus, as he stated, I'd probably over heat my amp. Considering the Amp is the nicest component of this system, I don't think I'll try that, lol.

So my only option is to disconnect the rear speakers ... OR... is it possible to somehow increase the ohms of the rear speakers via in-line capacitor or something? My deck says it supports "Speaker Impedance -- 4 - 8 ohms" so what if I could perhaps change the rear speaker to 6 ohms. Am I correct in thinking that I could effectively reduce how hard they are draining power from my deck allowing me to increase overall volume to help my pre-amp out voltage while still staying within non-distorted levels for my deck driven rear speakers. I mean, preferably, I'd like my rear speakers to be 10-20% quieter then my fronts but overall, I'd rather have *some* rear-fill then none. So I wouldn't even mind if I halved their volume even.

What's your thoughts on this guys?

-k

C-Man

Well one other thing you could do... going back to my suggestion... is wire the two rear speakers together, and wire the two fronts together, running each pair in each front channel, again getting the 2 ohm stereo load. Now the only reason I say you could do it this way is because a lot of amps have separate level adjustments for each channel of the amp. If you did it this way, you'd lose your right to left fade ability... but let's say you hook the two rear speakers up to the right channel... you could set the right channel level at half of what you set the left channel level at, which would cut the power seen by the rear speakers in half, so they would be quieter, not distort and you'd be able to turn the volume up much higher without the distortion you hear now. I hope this makes some sense. This is what I did in my dad's car. I had a two channel amp that I wired to all 4 of his speakers and it sounds great. He just has to remember if he wants to fade from front to rear he would adjust his deck from right to left...
Again, this will only work if each individual channel has it's own level adjustment. If the amp just has a front and rear adjustment, it won't work that way.

As far as running the highs at 2 ohms hurting the sq of the system... yes this is true. Well partially true, it really depends on the amp. You have a very nice amp there and I feel like if you were to run them this way you wouldn't notice a huge drop in quality. I've got a Zapco 2 channel amp that I run to 4 speakers and it sounds great still. Anywho you're probably gonna wanna do what I suggest or just disconnect the rears altogether. Another option of course would be what Jstas suggested and pick yourself up another amp to either drive your subs or your rear channels. Totally up to you. If it were me the first thing I'd do is disconnect those speakers and crank it up and see how it sounds, if it didn't sound good maybe try what I said.

Good luck

Wolfmag

Unfortunately, the amp only has a gain for each pair of channels and not each individual channels. I just might have disconnect the rears then...

But still is there a way to increase a speaker's ohm level? That idea still sounds appealing to me, if there is such a way.

-k

Jstas

There is no easy way to just drop the impedance of a speaker. If your rear speakers are factory speakers (I have not seen an 8 ohm aftermarket speaker since like 1989) then shitcan them. They are junk. Grab yourself even a cheap set of speakers and throw them in there. Even the cheapest speaker Crutchfield carries will be better than stock.

As far as the channels goes, if you bridge the front channels and run both speakers off of the one bridged channel, you lose your stereo imaging. Same goes for bridging the rear channels. Stereo is 2 channel. Bridging and wiring in series is just mono with 2 speakers. That is not stereo and it will sound like total crap. I would not even bother thinking about doing that. If you wire both front speakers to the front left channel and both rear speakers to the right front channel, you will still get stereo sound but, the sound stage will be somewhere hovering over the back seat. Also, if your front speakers are not as robust as the rear speakers, you will lose track information from the left channel because the speakers would be physically incapable of producing the same level of extreme frequecies as the right channel. The sound stage would be skewed to the rear. That is totally not what you want. If you are going to wire in a series then wire the left speakers to the front left channel and wire the right speakers to the front right channel. The runs will be long and impedance won't be exactly 2 ohms (if you use a pair of 4 ohm speakers in the rear rather than 8 ohms)because the length of the circuit will add impedance. That impedance would be about 2.6 ohms. It will however, be stereo. If you keep the crap **** 8 ohm speakers in the rear then you total impedance would be something like 1.8 ohms with factoring in the impedance of the circuit too. That's if my math for a parallel circuit is correct. For series, the impedance would 12 ohms for a 4 ohm and an 8 ohm speaker together and 8 ohms for a pair of 4 ohm speakers together.

But I still have to ask what kind of rear speakers do you have? If they can't take any power then 86'em and get some replacements. Seriously. It will eliminate 90% of the headaches you are currently having with the system.

What kind of car is this in anyway?

Wolfmag

It's a small car, Nissan 240sx.

I can live without rear speakers, I know... The speakers aren't that bad - they're aftermarket speakers: Alpine Sps-170a. The thing is, I'd like to keep them on my deck if possible.

If having really long wires added impedance, couldn’t I just add a **** load of wire length to the rear speaker to increase the Ohm load?

Jstas

Um no. Doesn't really work that way. You do not want to add impedance. You want to reduce impedance so a shorther wire length is what you want. I think you have your terminology backwards too. When you add impedance you would go up in number. 8 ohms plus another 8 ohms of impedance would be 16 ohms. Thatis if you wired in series. If you wired in parallel, you would drop impedance. You would have 1/8 + 1/8 = .250 then you divide 1 by .250 and get 4 ohms. You would reduce impedance then.

Wire itself has resistance but it makes a fairly small difference. A typical wire length in a car rarely adds more tha .01 ohms of resistance. To add an entire ohm, you would need lengths in excess of like 300 feet.

MTXMAN

as for how the guy got the voltage figgure on the sony deck... I can vouch for the specs, I called sony while i was still working at CC and up untill this year all the x-plode line (including your mp40) had 2v outputs... crappy decision on sony's part seeing as how this produced a dry deck with 2v outputs... BAD IDEA!!!!!

OldOneEye

Run your front speakers off your new amp, rear of the amp in your head unit, use the fader to set the level and your set.

When was the last time you went to a concert and they had a ton of speakers behind you? Fronts should be WAY louder than the back, so you won't need much power on the rears anyway.

Juan

MTXMAN

Juan,

While the competition defination of a good soundstage would involve having the sound coming from the windshield there are those who prefer a more balanced "surrounded" effect. Personally i like the sound to hover around my head giving a feeling of being enveloped by the music. Personal preferance should always dictate the location of and powering of speakers. After all he's the one who has to like it not you ;D