amp is shutting down Offset LED lit

sirogenous

I have a sony 2 channel amp XM-1002HX and use it to drive my DX3065s. The sony amp and the DX's along with my sony head unit CDX-8050 compose my entire system. When listening at higher volume levels the amp will sometimes shut itself down. According to the amp owners manual when a DC current is generated the Offset voltage LED appears amber. Telling me the reason why the amp shut itself down. Also, according to the owners manual the Offset voltage LED will appear amber when the voltage going out to the speaker terminal or the pin jack is too high. The manual says to make sure the speaker cord and ground lead are securely connected. I have checked all ground and power connections as well as every speaker wire connection. Every connection is tight and secure. The wire I use for the amps ground lead is 6 guage multi-strand wire and about 6 inches in length. The amps 12v positive lead is 10 feet or so of 8 guage muli-strand wire. Sony recommends using at least 10 guage wire so I'm well within specs. Anyone have any ideas why this is happening. This appears to be happening more often and at increasingly lower volume levels.

C-Man

Most of the guys on the forum will come out and say something smart like... it's a Sony....

Anywho, have you had this system for a while? Is it a new install? PBD or Jstas would probably have a better answer for you, but here's my suggestions. Try a new ground point. Make sure you've sanded down all paint/rust/urine stains.....whatever. I don't know a lot about the Sony amps because I've never owned one, but if it's a new install, maybe check to see that you don't have the amp set to bridged or mixed mode. Some other thoughts would be... Got speakers bridged... low battery voltage...

sirogenous

Thanks for the input. As far as my problem stemming from it being a somy amp, I can only hope the people who use this forum don't have their heads quite that far up their amps. Those that do would be quite shocked to learn what a vast majority of their favorite live albums were recorded with. The particular sony amp I have happens to a very nice amp. Not too many amps that I know are capable of producing 3.6 dB of dynamic headroom and do so without dropout. Anyways, the amp can be run in either Hi Current mode 1- 8 ohms or Hi Voltage mode 2- 8 ohms. I've used the amp only in Hi Voltage mode. The amp is not bridged nor do I have anyother speakers then the single DX3065 component speakers hooked up to it. I did the installation a little more then 2 and a half years ago myself and other then damaging one of the 6500 from using a little too much peak horsepower then they are designed to safely handle when the system was brand new, It's been glitch free. The system still continues to sound quite good. My only complaint is this occasional "shutting down" issue.

CPHILHOWER

I had the same problem with a Sony class "D" mono bass amp. Was running a pair of 15" Blaupunkt OverDrive DVC in 1 ohm mono. One GOOD loud BOOM and the "Overcurrent" Light came on. Was told something about the Sony not being able to deliver the "Current" needed to drive the subs. So I wound up buying a RF Punch 800.2.
Chris

sirogenous

Overcurrent isn't the problem I am experiencing, but thank you for your interest in trying to help. As I mentioned, my system still sounds great. It's just that sometimes it won't play at the volume levels it once did before without the Offset Voltage protection circuitry occasionally tripping and causing it to shut off. This amp is also a Class AB amp.

sntnsupermen131

problem number 1
its sony
possible reason why its shutting off...some amps have automatic cut off switches to where if it gets too hot...or if the amp "feels" likes its doing more than it can handle it stops...much like a person...do too much work...body tells you your tired...you pass out...
maybe you have your gain too high?
the connections on your rca cables are bad?
you can go to best buy...get a $10 pair of patch cables...run them from the amp to the head unit(dont go under the carpet and all that crap)and test your patch cables...sometimes the connectors lose contact with the wire...maybe thats your problem...if not...youre out $10...or you might even try to take them back
also, someone mentioned moving your ground....good advice...try that too
truthfully...its probably the amp
you say sony records albums and such...
true
sony makes tvs, computers, cameras, almost anything with electronics
my computer monitor is sony...i have a sony tv...i think my movie camera is sony...
all great stuff
but as far as car audio goes...sony is crap
sorry to break it to you
im not trying to be mean or anything
really...im not
but there is better stuff out their for the same price and itll actually do its rated power
-Cody

Jstas

I really hate it when people come in with a holier than thou attitude yet have minimal experience to back it up.

If Sony is so great for studio recordings then that is where they should stay. Last I checked though, Sony was only good at mass-production of already recorded master tracks. On top of that, they don't even make the hardware that is in the drives that they use. Also, go and actually look in the studios. The equipment does not say Sony. It's usually Korg or JBL or TEAC or Technics or any number of other companies I could name.

I interviewed at Sony Music right here in Pitman, NJ for a co-op job. Didn't take it 'cause I would have been an operator of one of the machines used for mass recording. That's not the kind of experience I wanted but I did get to see the operation.

As far as your amp problem, since you have managed to shoot down every suggestion so far, what do you think is the problem? It's getting obvious that you already have an idea and are just looking for someone to validate it.

As far as what I think, believe it or not, having a ground wire too big can cause a ground loop. Your protection circuitry does not fire up unless there is either a power surge from a bad ground or a bad battery cell or if there is a power surge from an excessive current draw. You may want to check your subs. A bad voice coil could be grounding out and causing your fault protection circuitry to engage.

Another thing is, where is your amp mounted? It'd better be insulated from metal because a chassis ground out can cause fault protection circuitry to engage. So can wiring a speaker out of polarity with the other channel. You know what else too? Excessive heat.

No matter how you cut it, if the fault protection circuitry lights up and shuts down the amp, there is a chance that something was damaged in the initial problem detection and it has just gotten progressivly worse.

Not knowing your complete install, how things are mounted and where they are mounted makes it difficult to pinpoint. Plus, the fact that it has been happening for a while now makes it all the more difficult. The problem could have caused other problems that have only contributed to the original problem and further muddled any diagnosis of the actual problem. If you want help, listen to what other people are saying and even if you think you checked it, do it again because you may have overlooked something.

As far as Sony quality, it's just not there. It's for the average guy who just wants something better than stock. It can't hang with higher end stuff, no way no how. It's like the saltine of the speaker world. A plain-jane speaker in a fancy wrapper to make you think it's more than it is. While it may work for you and others, the Sony gear is not up to par with some of the stuff that is in it's performance catergory and it outprices everything else it's performance category for less-than stellar performance.

Bottom line, this is experience talking, Sony doesn't hang for it's price. Electronic doodads, gizmos and fancy signal tailoring and power protection circuiry cannot compare to a good, clean power source and signal source. For that you need to look else where, not to Sony. Sony will do the job but there is a difference between doing the job and doing the job well.

This is all not to say that you made a bad choice. You made the choice you made, it's just not what most other people here would have made. Sony can make TV's, VCR's, DVD-players and even some decent home stereos but car audio is a place where they just don't cut it. They probably sell alot of stuff because of thier name but in the dB drag lanes, you are not very likely to see anything from Sony running in the top 10.

sirogenous

Thank you Jstas,

The information you have given me is genuinely appreciated. However, your attitude towards me is not. Perhaps someone could enlighten me as too where such a response from you is warranted. I come here for help and right off the bat I'm being attacked because I happen to own a sony product. Big fu@king deal. I didnt come asking to have my system criticized. I came here asking what might be causing my amplifiers Offset Voltage protection circuitry to trip. So excuse me for being slightly on the defensive. As far as me having the holier then thou attitude... Jstas....hello

Jstas

Looks to me like the first person to respond did not attack you but only warned you about possible bad receptions from some people here concerning Sony products.

All Cody or myself did was explain the reasons behind the bad feelings for Sony. Nobody attacked you or your Sony stuff until you opened your mouth with this statement:

...I can only hope the people who use this forum don't have their heads quite that far up their amps...

and then expected help after slinging the first insult.

I'd also like to know where I or Cody ever slammed you or your stereo? I looked through both posts and yes while some of the wording was harsh, I did not see anything deragatory towards you or your stereo.

Looks like you're the one with your head up your "amp".

Sorry for having an opinion based on experience and standing by it.

PoweredByDodge

Play nice kids...

DC offset is a *searching for right word* 'float' of relevant DC voltage.

if you have three sixteen volt batteries, and you're testing for compliance to that 16V measure, you can set a scope to a 16 volt offset.... then, when you put those batteries on the scope, it wont read 16 or 15.5 or 16.5, it'll read 0 (for perfect 16V) or -0.5 (for 15.5) or 0.5( for 16.5) --- you get the idea.

but that's in DC power applications... DC offset in audio is similar but different...

audio sound, as i'm sure you've figured out now, is a whole mess of sine waves superimposed on top of each other, or you can even look at it as one big sine waveform.

now ideally, that wave has half of itself above zero and half below zero on a graph, assuming the graph is not offset.

but, what if the wave is not half and half... from the little i've been reading on it, even something like 51/49 % isn't any good.

lets exaggerate it -- lets say its 75% / 25% --- so you've got that wave moved up or down -- the ONLY thing that can cause it to do that is DC Offset... now, according to what i said in the beginning, what does that mean??? --- it means that some amount of DC voltage is being put out along with the audio signal.

assuming that the amp is correct, and you do have this problem (you know it could be that theproblem does not exist and the actual problem is not the amp but the stupid protection circuitry -- its not common but it does happen)... but assuming the probem does exist...

if you had a plane jane 100 hertz sine wave going into your amp, and then the output of your amp hooked to an oscilloscope, with DC offset not engaged, you'd see that the wave was not centered, it'd be a little up or down of zero.

if you then played a 0 hz baseline (which isn't really good for your amp or speakers, but on low powr for a brief time for testing isn't gong to kill anything) with a given amplitude (say 2 volts) and you didn't get exactly that given 2 volts, then you're in ****... if its higher or lower then you've got DC offset.

do i recomend doing any of this testing -- no its a bloody pain in the ****... but i'm just explaining what's going on with your amp.

now, this problem can draw too much current and also even set off your over current protection (if u have it). eventually if the offset got bad enough, and you didn't have DC-offset protection, then it would offset the wave so bad that you might get over-voltage protection... and still yet if that didn't do it -- over more time -- thermal might kick in. personally i want an amp with no protection....lol.

anywho... unless the protection circuitry is faulty, you probably have an issue inside the amp. but here are a few other things it might be...

1- bad ground - swap out with same gauge as power (8) and then reground to new spot. -- check condition of under the hood ground wire from battery to block and battery to body.

2- noise in your lines. if you have enough line noise in your RCA's due to interference, i suppose it could cuase this effect however i'd think that you'd hear the absolute dog **** sound and notice it as sounding like crap -- i mean if u cant hear that amount of distortion and noise, then its not that.

3- your headunit may be putting out offset sine waves. it may have some problem and be doing that. there is an equally likely chance that your amp is screwed up inside as your head unit is screwed up inside.

4- you're playing a bunch of poorly recorded burned CD-R's... if u really have a choad of a mp3/wave, you can get DC offset output.


however, more than likely, something inside your amplifier, or inside your headunit is really out of kilter and acting up.

depending on whether its in the head / amp - pre-processing - pre amplifer stage / amp - post processing - pre amp stage / or amplifier - output stage is gonna determine exactly how to test for it -- well i kinda said that backwards -- the manner in which you exactly pin point it is going to tell you exactly where in the equipment it most likely is. as far as how to do that -- i dont know - i could think about it and come up with something, but at the moment i really can't put my finger on it.

either way -- u've got equipment problems... like Jstas said, its probably something that started out small, negligable, and is progressively getting worse and worse and worse.

now, after having said all that... i'll tell you this -- i do not recomend purchasing sony car audio. the reason is not "sony sucks" or "eww sony"... rather it is, "sony has a poor build quality with poor materials, and head to head with everything else remotely in the same price range the sony equip usually comes up short". Sony made a 2,000 watt amp circa 1995 --- all steel case and such... was a hell of a piece of equipment -- try to find one today, they still cost at least a 900 / 1000 bucks - even used. i liked mobile ES gear too.

but ever since the Xplod line came out, its been zip down the drain.

i hope its a cheap fix for u - but i dont think it will be - odd **** like this just doesnt' get fixed for pennies usually.

Jstas

I just thought of something else.

Barring any unusual circumstance leftover from the 80's and very early 90's where cars did not have common grounds, RCA cables are grounded internally to the head unit's internal common ground which then grounds to the car's electrical system common ground. Remember this whilst I 'splain it for a second!

Cars without common grounds have general grounds anchored throughout the car. Why? Because back in the pre-distributorless ignition system days, there was nothing in a car electronics wise that could over-come the resistance of the like-earth grounding situation of tying a ground to the chassis or frame of the car. Hell, even in Fords, which are notorious for being power-hungry, the highest draw was 30 amps for power seats and that was only to make sure the seat motors wouldn't burn out from an over-draw due to an extreme tank **** sitting in the seat.

Nowadays though, ignition, fuel, charging and even starting systems are high current and they have enough power to overcome the like-earth ground of the frame ofthe car, to the point where multiple general grounds could end up interefering with each other.

So what does all that have to do with anything? If these general grounds are affecting each other, they cause ground loops which can actually send a voltage signal back up a ground. Not good. So, when installing stereos, it is common practice to use a common ground for all stereo equipment, thereby minimizing the chances of external intereference and providing and squeaky clean power source. To aid in that, head units were grounded outside of the car's electrical harness. Sometimes actually, not always. So, for RCA cables to be properly grounded, they often came with a seperate grounding strap that got screwed into a grounding point at the back of the head unit, in the vincinity of the RCA jacks. This provided the RCA cables with that common ground acces.

Now that we know how a head unit chassis is grounded, we can understand why something like a pinched wire would cause such a problem. I had a problem with a Kenwood headunit in my Thunderbird. I installed it, the dash lights went out. When I pulled it back out to check, the dash lights came back on. It took a while to figure out what was happening. One of teh pressure clips was pinching the dimmer lead when squeezed by the headunit during installation. I trimmed back the lead and taped teh end with electrical tape and that solved my ground problem.

Bad grounds can cuse a host of problems and they show up many more places than people care to think.


Another thing to check is the fuses. Sometimes, fuses can fail the opposite way and get stuck "open" rather than burn out and "close" the connection. If a fuse has been stuck popen, it could be causing the voltage spike that your amplifier does not like. I'd pull the fuses and replace them anyway, just for good measure. They are like 50 cents a piece and good insurance. The fuse in the amp and/or headunit that is, not necessarily the fuse in the power cable. Although, you'll want to check that for corrosion too. Corrosion can end up grounding out a power or ground wire pre-maturly and it can even end up causing a power source. Water and corrosion inside a power line can end up causing a small battery to form which will change the characteristics of the power soure. It's rare but it can happen, especially if teh water is tap water or contaminated/acid rain. Also, if you battery is corroded, check your power wire to your amp. Corrosion can travel down a wire and cause major problems. I've seen entire automotive electrical systems get eaten up by corrosion driven by a battery trying to push power down a wire with a steadily decreasing cross-sectional area due to corrosion.

sirogenous

Jstas and other forum users,
I stand corrected and given the evidence below:
quote:

---

...I can only hope the people who use this forum don't have their heads quite that far up their amps...

---

I stand guilty as charged and offer my apologies for making the comment. I was out of line.

P.W.D.,
Your explaination into the properties of "Offset voltage" and it's implications in regards to my situation is greatly appreciated. As is everyone elses.

Thank You.

Jstas

Just trying to be helpful. I'm not always nice about it and can be opinionated also but at least its honest help. No hard feelings, no harm done.

sirogenous

As always Jstas,

Your help along with everyone else's is greatly appreciated.

It has been a few weeks since I last posted in this thread. This post is kinda a follow up on my current "Offset" problem. (pun intended) I took your advice Jstas and tried using a different pair of RCA cables. Unfortunately, my amp continues to shut itself down. I even went as far as to make sure the amp itself is not grounded thru it's mount also as you had mentioned. Before hand I opened up the amp to look for anything that didn't look right such as a burned resistor or transistor. Everything "appeared" to be okay. (Yes I reapplied a fresh coating of thermal paste on the heatsinks. Only I used the good stuff (arctic silver) wiping off the crap that sony used.
I did happen to notice a jumper that is labeled "protector off". If I can determine the source of my problem is the amp itself and not my headunit or the battery, I may do a little bit of de-soldering and remove the jumper. The jumper is routed thru the over-current and offset current protection circuitry. Powersupply circuitry has it's own independent protection circuit and the amps thermal protection circuitry appears to be independent of the rest as well. Who knows, perhaps this "Offset" problem is an error that Sony knows about and offers a "fix" by removing the "protector off" jumper. At any rate, what have I got to lose if it's the amp that has the problem and I end up frying it.

Jstas

Um, I don't recall what kind of car this all is in but a couple of things.

Number one, I doubt it is the head unit. If it was, you would get a deterorating signal most likely before it shut of completely or the head unit would just not work. But it apparently plays without a problem until the amp cuts out. Also, amps rarely cut out or trigger protection circutry for a measley 1-4v input signal that runs at less than half an amp in most cases. There isn't enough power to really damage anything aside from noise reduction circuitry but even then, it is possible but unlikely.

Number two, check the head unit the next time this happens. Pull it out of teh dash and check to see if it is scorching hot. If so, you found your problem and it's heat. The head until will be warm and maybe slightly painful to touch. The heat sync in the back will be untouchable in all cases but the case should be relativly tolerable. If it is way too hot to touch then the head unit is not being cooler properly. There isn't enough air flow over the chassis to dissapate heat. This can be a problem in today's overly cramped dashboards. Solving the problem is difficult but if you are creative, it can be helped. Something as simple as a spacer or rerouting wires can be the difference.

Barring that, I really douth the head unit is the problem. Fiddle with the amp if you want, as long as you don't void the warranty. If it has no warranty, play way. You may want to get it tested and even fixed though.

A question, does the amp get excessivly hot? If so, you may have a bad transformer in the amp. It won't show at ll in most cases and it can be hard to tell what went wrong. If you had a schematic, you could check the voltage drop or rise but I don't think you have one. If you have a friend with a spare amp or something, you might want to swap it out and see if the new amp has the same problems. If it doesn't, you know where the problem is.

PoweredByDodge

i dunno --- that "protector off" jumper deal.... here's my take on it.


some amps are being built with two purposes in mind. dual use as "daily driver" amps and "spl" amps. you mentioned that your amp is doubly-dubbed (god that sounded ****) as both a high voltage and high current amp, and can be "swapped" between the two modes.

one would think that if you were running it in high current mode for spl use, you may have to bypass the protection circuitry so as to get the extra peak juice out of it.

... i would venture to guess it is for THAT purpose that the jumper is present.

** on a side note - i use the **** heatsink compound - i can't get the stuff any cheaper than like 3 bucks for a skinny itty bitty tube - i dont even wanna know what the "good stuff" costs... unless you buy it by teh gallon nobody seems to watn to cut me a break **

USamps sells modification kits to do a few little tricks to their amps to pump out something like 50% more peak power.

so i wouldn't put it past sony to have that jumper there for the power output reason, rather than the "fix a bug" reason. -- companies are too much of penny pinchers to want to do something like that.... even the 1 cent it costs for a jumper or whatever is "expendable" to most corporations.

you obviously sound somewhat well rounded in electronics in general... can you get ahold of an oscilloscope ????? even a really **** crappy one... anything.

if you can -- hook it up in parallel to the speaker output of your amp (just tie + input of scope to the + subwoofer speaker wire... and - to -) ... play your system in a manner that normally causes it to go into protection. it'll look like crap.. its gonna be a big mess of fuzz and grossly unintelligable... but just look to see if half of it is above zero and half below.

then do the same thing with like a series of test tones --- either make your own, or buy one for like 10 bucks, or i can send you one that i made (i admit its ****, but its functional for me for now) for free.

make sure hte scope is zero-ed prior to hooking it to the speaker leads... check it for dead zero (no inputs) -- then hook it to a known DC source and nail the DC offset at nothing. (like a really good solid battery that you've confirmed the voltage of.

pop it on the speaker leads, play the test tone, and go for it... if you see the wave (it'll be one clear decent wave -- or if its mine it might be one fuzzy but sorta clear wave...lol) noticeably above or below - then you've got a problem.

also you can try playin your amp until it goes into protect... shutting it down, and then turning it back on as soon as possible with nothing -- like have your head unit set to "cd" with no cd in the player.... so that you've just got nothing going as far as signal.... watch the woofer cone... if it "pops" when it goes on like some amps do -- dont sweat it, but try to see if after a few seconds the cone is pushed in or pushed out more than it was when everything was turned off.

anyof this crap shows up then you're dealing with a "real" problem as opposed to the amp falsely going into protect.

sirogenous

hmmm, if my dad was still alive id be able to get my hands on an occilliscope no problem. However, currently I dont think I'd have much luck in finding one. Jstas mentioned overheating of the headunit. That could be a possibility since the headunits amp cannot be turned off when using just it's preamp as I have been. And the heat that the headunits builtin amp creates can be detected easily just by putting my hand near the face plate. It never made sense to me why it's builtin amp should be on if one chooses to use just the preamp.
The jumper that is labeled "protector off" doesnt appear to be labeled as such for "endusers" as desoldering it means having to remove the amps circuit board completely from the chassis to access the side where the solder joints are located for the jumper. Here's something I could not figure out what it's purpose could be. Located on one corner of the circuit board their is a very small incandesent light bulb. What purpose it serves i have no idea. If it's sony's idea of a cheap resistor, i dont care how good the amp sounds it's gettin tossed in my scrap aluminum bin. lol. But seriously, any ideas? I had been fairly impressed with the layout of the circuit board until I happened across the light bulb.
As far as the amp ever getting hot, it's the coolest running amp I have ever owned. Even on hot days driving with the windows up and playing music at loud volume levels its always remained just slightly warm to the touch.
Also, there are certain songs that when played at loud volume levels will trip the amps "Offset" circuitry at pretty much the same location on the music track each and every time. The moment being where the amp shuts itself off is at a point where the music is placing a huge demand on the amp with a lot of overtones and harmonics being played at once. The music in question is Metallica's Garage days rerevisited 87' Stone cold crazy. It will shut down the amp at the same spot every time.

P.S. The thermal paste comes to me at "you've gottabe kiddin'me" prices too. I think I paid 8 dollars for something like 1 ml. of the stuff. Just enough for removing my P4's CPU HSF twice, replacing the HSF on my video card, and the two aluminum heat sink rails that run along the entire length of the amps chassis on two sides. It made for a 3 to 4 degree difference in temp for my cpu as compared to Radio Shacks thermal paste. Although lapping my CPU's HS made the biggest difference of nearly another 5 degrees F. at idle and a whopping 14 degrees under load.

sirogenous

I just finished doing some reading on offset voltages and mosfet amplifiers. To summerize my findings I found an interesting link. www.analog.com/library/analogDialogue/Anniversary/6.html this link was quite helpful in getting me to understand a little better the causes of Offset voltages in amplifiers. High temps and cheap components and/or damaged diodes seem a very possible cause of my Offset problem. Now...if I could only offset my Offset voltage issue. Hmmmm lol

PoweredByDodge

there are usually two to six op-amps inside an amplifier. most have four. they may or may not all be the same, but if they are different, they will be paired (2 and 2 / 3 and 3).

if the **** end of the amp is fine, then i can see the problem coming from processing somewhere, as you are indicating with the website link you posted.

cody's did that to me on a wicked scale -- put out massive amounts of DC power, pushed a woofer cone straight out of the box and never let it return. flip the leads, sucked it in. the output stage was fine, power supply was fine, replaced the one damaged op amp ... but i could not find the actual problem. fixed about 10 things that the problem had fried, cooked, or killed, but couldn't find what was causing the ridiculous amounts of DC output to the speaker terminals.

i dont know what the hell a LIGHTBULB is doing in an amplifier circuit board ... maybe its for cosmetic purposes? does it have some plastic thing near it that maybe it lights up and shines when the amp is on (much like JBL's power valve sub amps with the orange glow from their bottom) ?? far as being a cheap resistor... i'd imagine carbon film, or even metal film resistors, would be cheaper than a light bulb.

all i can think of is if an op amp does not have proper feedback, it can become a bit "un-bridled" and fk itself up. cheap parts, instead of just BREAKING tend to slowly go to hell, and only at high power or heavy loads do they show signs of going bad... but eventually they'll go bad.

just about every amp on the maket has cheap parts... some are worse than others though.

the amp i was most impressed with the layout of is that radio shack amp i've got. honestly, its the simple-est thing in the world, puts out 75 x 4 / 200 x 2 bridged and is quite good sounding... yet the board is like... child's play. it's the kind of thing that if you had a giant bare universal circuit board, you could build the whole thing yourself with a little ingenuity. but with progress comes complications... as thus we see just about every amp today give a person a headache just looking at it.

on a side note about heat in general -- i rebuilt a blue thunder 754 to use on my fronts, and obviously i used the only paste i had at my access, the radio shack stuff, now i've got it running pretty strong, 200 or so by 2 bridged (its rated can do 280 x 2 but i've got the gain back a bit -- its on a set of components), and i noticed since its been prettty hot here lately (80 - 90 degrees), its getting hot as hell. so much so that you dont want to touch the case when it gets hot, i dont think yo'd get burned, but it's just that sort of temperature that you can't bear to keep your hand there. also - when rebuilding it, i put about 6 or 7 THIN coats of paint (prime / base / clear @ 2 each ) on it - but not before sanding it down pretty good... and that was only on the end caps -- the center portion just has 3 coats of clear as it was not chipped up. any ideas on how to reduce heat ????? its in an x cab truck, bolted to a center mount that has absolutely no obstructions to air flow in any direction and is fully open to the whole back of the cabin.

sntnsupermen131

do those little fans you can buy to help keep your amps cooler work?
-Cody

sirogenous

As far as lowering your amp temperature there are several things you can do that will work. First off, from what I have read, make sure the amps power transistors, FETS, Op amps, whatever your amp has, make sure you crank em down as tight as you can against the heatsink. They're talkin ft.lbs of torque not in.lbs of torque. Maximum surface to surface contact is critical. So look for any nicks, burrs or scratches on the surfaces pressed up against the Op amp transistors and be sure to use (you know this one already) heatsink paste or h.sink tape. Sorry about this next one P.B.D. but you don't want anything between the metal of the heatsink and it's contact with the air. That means no paint or clearcoating of the heatsink fins. Removing such from the heatsink fins should make quite a noticeable difference in temp. Probably by as much as 10 or more degrees. The next idea that you can do is to use brushless computer fans. You can find them at your local electrical surplus store for 3 to 5 dollars each. The bigger the fan the better the ratio of CFM of air vs. fan noise. 120mm or 4 inch fans work well as do the 80mm or 3 inch ones. PanaFlo make great 3" fans that are extremely quiet as does Rotron. ALthough the Radio Shack fans work, they extremely pricey plus tend to be much louder the the Panaflows. Also look for fans that have ball bearings instead of bushings. Bearings not only last longer they are much quietier too. If you want to get tricky you can make a simple thermal fan control unit using a thermasistor and a relay to control when the fans come on. If youre into fancy flashing lights and want to impress with all the showy style you can, they now make these fans with little red or blue LEDs in them. Making a neat blurry neon blue or red glow as they spin. Fry's offers them for about 10 dollars and up along with thermal controller kits to run the fans for fairly cheap too if you'd rather not build one from scratch.
This is knowledge I've gained over the years from overclocking computers. And with the help of being able to access a huge knowledge base lot of information derived from the masses of computer geeks and guru's over at www.Overclockers.com. I dont see why an amp should be any different the a CPU. Drop the impedence to zero and lets see what this baby can realy do. If it starts to get hot will just chill it down to -40C using vapor-phase cooing or liquid fluorocarbon even a cryogenic cooler. Yeah baby! Oh...ooops...sorry I think I got carried away abit.

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well see guys i was hopin to avoid a fan as there really is no spot on the darn amp that i have a clear shot to just cut a hole in the case and put a fan in.

... unless i went right through the top cover... that would be ugly as sin.

raising the amp a few inches off the mount and putting a fan underneath wouldn't do any good probably. it'd have to be somewhere in relation to the heatsink.

the only other thing would be to get a very large blower type fan, mount it to the back of my middle seat, and let it blow over everything... that's even ****-er.

I'll open up the case and tighten everything down -- i had always been of the idea that "hand tight" but not "tight tight" were the way to go as there was a chance of smooshing / cracking the plastic transistor cases... but if u say its safe, i'll crank em down harder.

the paint i cant do anything about -- the amp was powder coated painted when it was sold new -- that's like normal for them... i sanded most of that off when i did the repaint... i figure about 2 - 3 coats of autobody paint is about as bad as one good powder coat... so i kinda did double as much paint as i should have, but at least it looks really nice...lol.

sirogenous

You'll get much better cooling by mounting the box fans (computer fans) so that they blow cool air across the outside surface of the heatsinks then you would by placing them in a manner that they blow or pull air past the components inside the amp. That's because heatsinks are far more efficient at transferring heat away from the transisitors then air is. Air actually makes a better insulator then it does a conductor of heat. Although aluminum conducts heat well it's not quite as efficient as copper or silver which are some of the top conductors of heat. However, aluminum although not quite as good a conductor as copper or silver it is still probably 100 times more efficient at transferring heat then air is. Blower fans are an excellent means of moving large volumes of air at low sound pressure levels. The only drawback to using them is that they are usually not as compact as a 3" or 4" box fan although they do tend to move more CFM of air in ratio to their size vs. box fans. I would think one 4" box fan or two 3" box fans would provide your amp with adequate cooling as long as they're exhaust is able to blow directly over the heatsinks. Designing a bracket to hold the fans should be fairly straight forward. As I mentioned before, avoid mounting the fans in away so they pull air past the heatsinks. Reason being is that unless the air is just about to enter the fan blades the air being drawn in isn't focused acrossed the heatsinks. Also the air tends to travel in a more laminar fashion. The turbulent air of the exhaust can be focused easier plus turbulent air mixes better with the heat saturated air that's been in contact with the heatsinks.

sirogenous

I don't suppose you know of a reputable person or business in the InSANe Diego, CA. area that do repairs on amplifiers. I have an ol' Haffler DH220 that needs some work done to it as well as a real dinosaur, a Concord CA30.4 car audio amp. In it's day it was a nice amp. By today's standards it's a bit underpowered and it's 15 V/microsecond slew rate leaves a little to be desired, but it's perfect for powering a pair of mids or tweeters. I'm guessing one of the main filter capacitors must be going bad due to the high pitched wine that it emits from somewhere inside the amplifier itself. I'm not aware of anything else that one would find inside an amp that is able to emit a loud audible noise. Anyways, I figured it couldn't hurt to ask. Seeing how Polks customer service is located here in San Diego one never knows if you guys are as well. Anyways, Thank You for all your help. Hope I was at least a little helpful to you in your quest for a cooler running amp. Cheers

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hmm - actually you've been quite helpful - i had always though that mounting a fan INSIDE an amp blowing out (like a computer power supply fan blows from inside the case out of it) was the way to go, but what you've said makes sense.. now its simply a matter of constructing something decent looking / discrete / and viable for mounting said fans.

since my capacitor bank is all of a 8 inches away from my first amp, and about a foot away from the hot amp... i believe a blower type of fan mounted in a carpeted "enclosure" or some type of deal that was built as part of my capacitor bank (thus not looking retarded or anything) would do the job.

i really put the frickin pressure on the sink mount bars before i ripped off my air filter assembly yesterday (yes - yesterday was "rip apart your truck and throw factory parts in the garbage" day ). its not been as warm, and i haven' tplayed the radio yet, so i can't tellyou if its made any difference, although i'll say this -- they were "very snug" before... they're "you'd need a ratchet to get them off cuz that's what i put them on with" tight now. i realize why they use hex nuts not instead of like phillips screws... you cant torque on a phillips screw as much as a hex head nut.

as far as amp repair companies... i have no idea whatsoever... there is this place over here called the "Hi-Fi hospital" that everyone swears by, but i think they're a bunch of ravenous thieves with soldering irons -- just my opinion though. forgive my lack of home audio knowledge or even audio history at that, but are either of those two companies still in business?? if so - may they possibly do repair still? usually, unless you're doing it yourself or having somebody who knows their tech doing it for you, you're better off sending stuff back to the MFG, as most local shops tend to not know too much about anything... even if theyr'e remotely well educated. it's just hard to siphon through a board that is not "typical". advanced designs and old designs -- and espeically advanced old designs -- give your average repair guy a heart attack.

as far as the 15v/us slew rate having much to be desired of -- APPARENTLY YOU HAVEN'T BEEN READING MUCH OF THIS FORUM LATELY. lolol

there's a whole mess of car audio amps with that specification or even worse. car audio amps are starting to polarize themselves dude... the midgrade companies are trying to build cheaper and cheaper, but still high power products... so they're fudging numbers, having higher power outputs and lower slew rates and damping factors to save money but still go "boom". on the other end the better companies are saying "well this is outrageous that everybody else is going to pot... we're gonna make sick **** good stuff and make everybody else grovel at our feet"... so you've got amp prices going up on the higher end stuff that i coudln't even afford when it was lower priced and have been thus lusting after with no hope of ever owning. -- USamps -- 150 volts/us .... ya... i know... u want one don't you...lolol.

sirogenous

One thing I overlooked as far as my mentioning about placing a fan inside the case. Although, mounting a small fan inside the case might not do much for cooling down the main transistors that have the benefit of a heatsink to transfer heat energy away from them, it might benefit some of the other components that aren't connected to a heatsink. Such as main power transistor's diodes and some of the many smaller NPN transistors. Just because most of these parts are able to operate within their rated parameters at the temperature anticipated by the engineers who designed the amp, doesn't mean that cooler temps all the way around wouldn't be beneficial. Just how much heat is generated by the board components I know not. How much these components would benefit with the addition of running 1 or 2 degrees cooler is probably marginal at best. Many manufactures of transistors as well as some diodes list the tolerances given for the device in increments of 10 degrees. I forget if that's given in Celcius or F.
As far as Hafler being in business still I'm fairly certain that they are. As far as Concord being in business, last I heard they were not. Also, my sony amp is beginning to worsen at an increasingly faster rate. Still the problem does not occur until I'm at fairly loud listening levels, it's shutting down more and more often. I find it odd though that musically, before it shuts itself down, there is no degredation of sound quality. I turn it off, immediately turn it back on and it keeps on truckin until I push it a bit. I now understand what you have all pointed out to me in regards to sony car audio using shoddy parts. It's really disappointing to me. They desiged a very nice amp on paper. Then went ahead and used non-superior parts or part (it only takes one) and walla, a really great amp just became one of frustration and a loss of future revenues for sony. Same thing happened to Asus... (sigh!!!!)

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*twiddles fingers*

ya know -- if you dont really care if the thing lives or dies, and its out of warranty, and u would intend to get something else if its busted bad -- then u may want to think about the messed up protection circuitry and try to somehow disable the protectioin circuitry ... how to do it -- i dunno... would have to look at the amp, and even then i'd be like "hmm....." -- sniff around in there, u'll prolly be able to figure out where the annoying thing is -- like thermistors for thermal protect are easy -- just pull them up from under the heatsink bolt down bars or even snip one of the wires going to them... boom no more thermal protect. dunno about the voltage deal but u can prolly dig it up.

sirogenous

I'm fairly temped to go that route. As I am sure that one jumper that is printed on the circuit board as: "protector off" is there to disable the that part of it protection circuitry. As I mentioned before the power supply would remain protected. (at least I'm fairly certain. Of coarse it really wouldn't matter would it lol) I think I'll bring it in to sony's customer service and see how much they want to repair it. Right off the bat I'm sure they'll want at least $100 bucks just to look at it. The only thing that really concerns me about turning off the protection circuitry is that the Offset protection circuitry is to protect the speakers when it detects to much DC current going to them. I can just see it now...crankin up my tunes then hearing a muddled thump and then all goes quiet cause the amp just sent 12 volts or more of direct current into my DX3065's. Yikes!. I don't even like to ponder that idea. I do have some old Pioneer 61/2" component speakers. I could always install them temporarily to see if they get damaged. I don't mind sacrificing them since they've been sitting around unused for 4 or 5 years. Like I said, this whole thing is getting me frustrated. This amp has given me about 4 years of solid reliable service. When you look at how it was designed it is a thing of beauty. There is not a single wire anywhere inside the amp. It is clea--eeen. Nice thick 5 or 6 layer IC board. Everthing is securely fixed to the board. Even the diodes for the main transistors are attached to the heatsink for cooling. The light bulb makes me wonder abit as I cannot see what purpose it could serve. Anyways..., I owned my share of high-end amps and sound wise it has always performed beautifully.

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as far as mounting chips to the sink - just about every amp on the market today (of decent quality) has the power supply diodes mounted to the heatsink. doing it any other way screams "fire fire fire" *beavis voice*.

i've never had a sony apart so i can't speak on it - but they've had (in general) nice looking circuit boards (TV's / head units / home audio stuff... yada yada) ... i still wish i knew what the bulb was for - like you're sayin - if only so that i could go tell someone "hey get this - sony amps have a frickin bulb inside them for XYZ reason".

sirogenous

As soon as I can get ahold of a digital camera, I'll post some pics of the light bulb. I too would love to know what the heck is sony doing placiing incandescent light bulbs in their amplfiers. Well, I contacted sony about making repairs. They want a flat rate of 99 dollars for repairs, return shipping included. However, if for some reason they feel it does not meet their flat rate pricing requirements then they want 26 dollars for running a diagnostic on it plus the cost of any parts. However, I would have to ship the amp to Michigan or drive all the way to Irvine ( about 160 miles round trip ) to drop it off. I'd perfer it if they'd send me the schematics but I've heard that sony only does so upon licensing agreements and healthy amounts of cash sent their way.

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100 bucks is about normal...

what's your amp rated at anyway? like 150 x 2 ?

you can prolly snag a new amp that is 150 x 2 stereo or 150 - 200 x 2 bridged for like 200 bucks -- 150 bucks if u go cheap.

sounddomain tends to have **** mega cheap -- hifonics stuff has a ton of instant rebates right now (up to 175 off on some amps) and they're good product.