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New member Username: MekimboPost Number: 1 Registered: Aug-11 | Hey, Sorry if this is wrong section, my first post. Today I installed a 600w amp and sub, my first time. Went well, only problem was my ground was bad, but found another and it worked first time. My problem is that my front speaker(s) (it seems to be the left front) distorts in some songs, not so apparent in others. even at low volume. Increasing volume doesn't seem to make matters much worse. It's like they're overpowered. I've tried using same head unit settings (fade / bass / loudness etc) The amp is ONLY powering the sub, the rear and fronts are still hooked to the head unit. I didn't notice the problem the first, but have tweaked the gain and freq / bass knobs on the amp since install. Any ideas ? Thanks in advance |
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Silver Member Username: Joe1234Post Number: 240 Registered: May-09 | So the problem existed before installing the sub right?? Well the first thing do is to use an original CD that you have heard elsewhere and its good. Zero all tone controls, balance, fader, loudness and enable HPF if your head unit has it. if that fails swap your front speakers, and check that none is loose and the speaker connections are not loose. Also could be a good idea to list all your component models models. |
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Platinum Member Username: GlasswolfColumbia, South Carolina Post Number: 14472 Registered: Dec-03 | the problem is very likely due to the head unit powering the front speakers. 12 watts per channel just isn't enough to keep up with an amplifier-driven subwoofer. put a 2 channel amp on the front speakers, and youor problem should be fixed. If the distortion is a scratchy sound and happens at any volume, then the issue is most likely a blown voice coil in one of the speakers, caused most times by distortion or clipping. head units clip at 2/3 max volume most times, or less. This is another reason it's good to use a dedicated amplifier for all speakers, and not to use head unit power. |
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New member Username: MekimboPost Number: 3 Registered: Aug-11 | Thanks for the reply GlassWolf. 1. Why would my amp via pre-outs affect the fronts via the head ? totally different circuit, unified by only the ground :s 2. They were fine before amp installed, why the need for an amp for fronts ? 3. Not scratchy sound, almost like they're clipping. bass is fine, and happens at all volumes, but only certain songs. 4. Front speaker sounds fine, 120hz cut off, just different songs :S Unless you have any more suggestions guess i need to replace the front speakers ... @ 600 w it can't be a power issue can it ? Ta |
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New member Username: MekimboPost Number: 4 Registered: Aug-11 | joe1234 no, problem existed AFTER installing. |
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Silver Member Username: Joe1234Post Number: 245 Registered: May-09 | If you disconnect the RCAs at the new amp all goes back to normal? |
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New member Username: MekimboPost Number: 6 Registered: Aug-11 | joe1234 no, problem existed AFTER installing. |
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Silver Member Username: Joe1234Post Number: 249 Registered: May-09 | Yes you stated that all was fine until you installed, so just to make sure I would leave out for a moment the amp by disconnecting the RCAs and see if the problem goes away. If the problem goes away after pulling out the RCAs you don't really need to change speakers, maybe the amp just drags too much power and affects a little your HU. Many times a HU can get damaged when the amplifier loses ground since it will ground itsef through the HU. |
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Platinum Member Username: GlasswolfColumbia, South Carolina Post Number: 14481 Registered: Dec-03 | did you rewire the door speakers? It's not uncommon to have one of the terminals on the back of the speaker ground out to something metal when re-inserting the speaker into the door. I've seen it happen a lot. |
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Platinum Member Username: GlasswolfColumbia, South Carolina Post Number: 14482 Registered: Dec-03 | also:" >1. Why would my amp via pre-outs affect the fronts via the head ? totally different circuit, unified by only the ground :s I never said that per se. I said the amp-driven sub will overwhelm the head unit driven door speakers, which temps people to turn up the volume on the radio, causing the amp in the head unit to clip, which in turn damages the door speakers. a 12 watt per channel head unit just can't compete with a sub with hundreds of watts. you drown out the vocals. This is why I suggested using an amp for the doors. Having sufficient clean power to the door speakers will not only avoid clipping damage to the speakers, but it will give you a more balanced, cleaner sounding system. >2. They were fine before amp installed, why the need for an amp for fronts ? see 1. balance, and avoidance of clipping. a head unit's IC driven amplifier lacking a transformer, just isn't able to provide clean power at even moderate volumes. This clipping will damage the coils on your speakers which may be the source of your problem. >3. Not scratchy sound, almost like they're clipping. bass is fine, and happens at all volumes, but only certain songs. >4. Front speaker sounds fine, 120hz cut off, just different songs :S OK, try a high pass filter at 150 or 200Hz. I don't know what the Q is for that crossover, but if it's variable, try 18dB/octave. The slope may be shallow enough that even at 120Hz, you're still getting plenty of output one to two octaves below that point, which is causing the distortion. |
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Silver Member Username: Joe1234Post Number: 252 Registered: May-09 | Since all was fine before the install I would suggest as first test: -Removing the RCAs from the amp. -Remove the inline fuse that powers the amp -see if your system returns to normal. |
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New member Username: MekimboPost Number: 8 Registered: Aug-11 | Thanks for all the replies, I tried your suggestions, but I figured out the problem in the end. I know everyone says grounding is the most common cause, but I was sure I had a good ground, however, I filed another point down, and seems to have gotten rid of the problem. The sound from the dash and rear door speakers seems fine now at the vols I listen to, would you still recommend running them through a separate amp? would a cheap 150w dual channel be ok? I want to keep costs down while getting a fairly decent result. Also, I want to add another 600w amp and sub. So, with a 2 x 600w amps, two 600w subs, would I need to upgrade the 8AWG power and ground cables to 4 AWG ? Or would I be okay just replacing the 30 amp fuse at the battery lead with a 50 or 60 amp ? Thanks in advance... |
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Silver Member Username: Joe1234Post Number: 255 Registered: May-09 | Ok Kim should you have followed the steps of my previous post the system had returned to normal in this case, I am glad that you took the next step which was indeed check the amp's ground, Some HU react to high ground currents in a horrible way, like some Pioneers a few years back. I would still recommend an amp for all your speakers, not a junk amp, maybe a used good quality 4 channel amp for your speakers it will improve sound quality and loudness incredibly. Regarding to the bass amps if those watts you specify are RMS watts you are already thin with 8AWG, if you only replace a fuse most likely you will overheat the wires which can lead to all bad consequences. To avoid making suggestions that would make you overspend it would be best if you listed the components you already have: HU, amp, speakers, sub, etc |
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New member Username: MekimboPost Number: 9 Registered: Aug-11 | Thanks Joe Durkham, It's a cheap Sub Zero 600w amp/sub package including the cables. Cheap I know, but it seems pretty and is my first install. I paid £65 for the kit from ebay, and would like to install another. I believe the rating is peak as most are, so am i right in assuming divide by three to get RMS ? (150w) I get confused, but my understanding is RMS, x 2 = MPO x2 = PMPO (peak) ?? The HU is a Pioneer 2300UB, stock speakers (Saab 900s). I'm looking to upgrade the speakers eventually too. Regarding cable overheating, wouldn't the fuse blow before that ? Thanks |
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Silver Member Username: Joe1234Post Number: 257 Registered: May-09 | Kim, if you would like to install a second amp and don't want to spend in new wiring then just wire the second amp independently with the wires that it comes with. You usually can judge power of an amp by the fuse rating it uses,if it is 30A then: P=VxI = 12x30 = 360W but it will never reach that or the fuse will blow so say is 300W but since some power is lost in heat then: Pd = Pt x Eff = 300x0.75 = 225 W RMS That is a raw estimate of the real power delivered by the amp. PMPO rating is a scam basically, every company will define it with their own method and is totally unreliable can usually be 3 to 5 times the RMS real power of the amp. Since you are running stock speakers I would wait to get better speakers to amp them, there is another thing since the 2300UB has only a single RCA pair out, to add a speakers amp you will need to send a full range signal, that means that all amps will need to have crossover themselves, LPF for both sub amps and HPF for the speakers amp, seems like a lot of work but it can be done. Regarding your last question, the cable you have will not overheat with the 30A original fuse but if you install say a 60A fuse this wont blow at 30 A obviously so the wire will sustain higher currents than intended and overheat. |
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Platinum Member Username: GlasswolfColumbia, South Carolina Post Number: 14485 Registered: Dec-03 | 1. grounds should always be to bare, sanded metal. no paint, and securely bolted or screwed into place. 2. yes you'd want to upgrade from 8awg to 4awg for 1200 watts RMS. that's about a peak of 120A of current with class D amplfiiers, and at that point if you start to note a dimming of lights, distortion, etc.. this could be sagging voltage rails and amplifier clipping which will result in a need for a larger alternator, or lower volume levels. |
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New member Username: MekimboPost Number: 10 Registered: Aug-11 | Thanks Joe and Glasswolf. You've cleared that up for me, I think. Since my amp(s) are rated 600w, that's most like NOT RMS, so what is the likely RMS wattage ? I looked in the manual and only states 600w. The amp retails for about £30 - 40 new. The reason I don't want to lay more power lead unless I have to, is there is little room to pass another lead through the firewall, and getting my glovebox back on was a nightmare. Going by this, do you think I could get away with using the 8AWG for two amps ? I'm more bothered about a second sub at the moment, rather than the front speakers... |
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Silver Member Username: Joe1234Post Number: 259 Registered: May-09 | Your amps come each with an 8AWG putting 2 amps on a single cable wouldn't be wise but if you wish to try, place a 50A fuse and see if it blows at max power, if it does then I would better go for lower gauge. |
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Platinum Member Username: GlasswolfColumbia, South Carolina Post Number: 14490 Registered: Dec-03 | http://www.glasswolf.net/papers/charging.html chart at bottom of the page use that as a starting point for wire size. the12volt.com has a good chart too. |
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Bronze Member Username: MekimboPost Number: 11 Registered: Aug-11 | joe1324 , sorry, just got back from holiday. My amp manual says 600 maximum (which I take as being peak) power. Therefore is it logical to conclude that my RMS is in fact 300 ? or 150 ? That (300w) would leave me well in the range of a 60amp fuse and thus a 8AWG wire would be sufficent ... glasswolf , thanks for the info, been really helpful, lots of useful bits on your site. Input from you both on all of this would be very much appreciated as setting this up soon - just a re-cap, adding a 2nd 600w sub and amp, hopefully using single 8AWG, but if I really have to, running a 2nd 4AWG - will I get away with 8AWG ? Cheers in advance Kim |
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Silver Member Username: Joe1234Post Number: 322 Registered: May-09 | Half of peak rating is a reasonable assumption for amps so 300+300 = 600W is what both amps would be taking up so: 600/12 = 50A, If the 50A fuse never blows then not even 600W are being taken up. Maybe one question would be is if you know the actual length of the cable you are actually using (battery to amp). Of course if you run a second 8 AWG all will be fine, no need to get a 4AWG at all. |
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Platinum Member Username: GlasswolfColumbia, South Carolina Post Number: 14501 Registered: Dec-03 | A few more tidbits to consider: RMS is 0.606 of "peak" in mathematical terms. However, car stereo companies don't always follow this, and can sometimes rate "peak" as what the power supply is rated to deliver, as opposed to the amp's finals, or output stage, and a good amp should have a power supply able to produce at least 3 times the rated output, if that gives you any idea of how much the peak ratings can vary. As for the power wire, I know it's a pain, but 4AWG is really your best bet. wire is rated in AWG (American Wire Gauge) or mm cross-section, both of which measure the diameter of the actual wire without the insulating sleeve. That being said, with direct current (DC) voltage, the wire's capability to carry that current is limited by the gauge (or cross section), and the length of that wire. The longer the wire, (both positive and ground combined, or the "complete circuit") the larger the wire gauge needs to be. If you're looking, just as an example, at a 15 foot length run of wire for a pair of 600 watt RMS amplifiers (based on the load presented by the speakers, and how they're wired to those amps!) and both amps are class D (say 80% efficient) you're looking at 120A of current draw (peak, or at the most) sustained at full output, theoretically. (I say this because there are a number of factors that affect the output of the amp, like the fact that speaker load varies constantly based on box specs, environment, frequency produced, etc. they are a reactive load, as well as volume level, and the reference level of the material being played, since 0dB is ref, and music is usually recorded around -20dBREF) I'm guessing you bought that amp/sub combo on ebay.uk for the Sub Zero Ice SPLA600 2 channel amplifier and subwoofer in box? I see several listings for this product package, but I can't find anything for specs on it, so since the sub is rated for 200 watts RMS, I will go on the safe side and guess the RMS output of the amp is around 200WRMS as well.. but that is a serious WAG so don't bet any money on those numbers. |
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Silver Member Username: Joe1234Post Number: 323 Registered: May-09 | Rather 0.707 or 1/Sqrt(2) and maybe is a good estimate of RMS power rating for FM broadcasting amps. |
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Platinum Member Username: GlasswolfColumbia, South Carolina Post Number: 14503 Registered: Dec-03 | (a / sqrt(2)), where a is the amplitude for AC sine wave, yeah. I was just being vague. sorry. I had someone standing behind me yakking and trying to get me to leave. |
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Bronze Member Username: MekimboPost Number: 12 Registered: Aug-11 | Thanks for the advice, got the 2nd sub installed, all running fine, checked the power cables, they don't seem even warm, so the current is fine. I'm running both 600w amp and subs (1200w total peak), STILL USING THE 30AMP INLINE FUSE from the battery !! I don't know why it hasn't blown. I want to add some 4" coaxial dashboard speakers, just to cover mid and highs. The ones I have distort, and everyone says upgrades are a good move. I will try them on their own expecting to add a 2 channel amp if they turn out to be underpowered by my Pioneer HU (4 x 50w, 22w RMS) Can I pick your brains, what am I ideally looking for. I love lots of (clear) treble, so good tweeters are needed, but clarity in the mids is important too. I'm assuming I can leave the rear 6"s as a fill-in by the HU, would they get more juice since the fronts will be powered by a separate amp ? (4 x 50w would equate to 2 x 100w) As well as the type of 4" coxial (dashboard speakers), what wattage of amp would do the job of powering them ? Do I need crossover units if I'm not using an amp? I guess the amp crossover switch would be enough... Thanks |
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Silver Member Username: Joe1234Post Number: 343 Registered: May-09 | Ok Kim, regarding the cable and the fuse a few things are possible: 1) The amplifiers are seriously overrated or their input gain are limited. 2) your subwoofers act like midbass drivers. 3) your tone controls are low on bass. I would ask you what is the brand and model of the subs. Regarding the speakers, yes try to wire them through an amp first to see if they improve enough, if not the following will play low enough to get you mid to highs: http://www.onlinecarstereo.com/CarAudio/p_25135_Pioneer_TS-G1043R.aspx 4" speakers don't require much power 25-35W RMS at most. Hope I am not going over budget with those (let me know). Anyways I would wire all four speakers to the amp, 50W to each will be plenty, of course you can try powering the front speakers alone, try it both ways Ideally all four speakers should be upgraded to get best results but yes make gradual changes until you are satisfied. |
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Bronze Member Username: MekimboPost Number: 13 Registered: Aug-11 | Thanks Joe1234 But my subs are running fine, was just saying i don't know why the 30amp (rated for the ONE 600w sub) was ok powering both 600ws. But hey, they're ok so far. leads are cold, so no melting Thanks for the speaker suggestion, but i'm in the UK, guess I'll just find an alternative. |
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Silver Member Username: Joe1234Post Number: 345 Registered: May-09 | Kim, the fuse dones't blow simply because not even 30A are going through the line, and that's why the cable do not show signs of overheating. In reality you are getting no more 300-330 watts of the 600W (1200 peak) you are supposed to be getting. That thing should be playing much louder so you may need to look into it. Here is the same speaker from a UK seller free shipping: Of course there are many alternatives out there but these sound clean and lower than average. |
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New member Username: MytonyPost Number: 2 Registered: Sep-11 | No problem. |