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Page updated on March 17, 2008

Do you have an Audio question?

With Home Theater, DVD, DAT, DCC, Fiber Optics and all the new audio technology available, it's easy to get lost in the shuffle of protocols and impedances.

An Anecdote

One spring afternoon, I was in a major department store, when I noticed an affluent looking woman speaking to one of the sales people.  She asked, "I have four pairs of speakers hooked to my 60 watt stereo.  When I have it playing at a good listening level, it shuts itself off and a red light that says 'Protection' lights up on the front.  I can shut the power switch off and it will come back on, but it just goes off again.  I know I have all the wires twisted together real good, so it can't be a bad connection.  Do I need more power?"

The salesperson replied, "Yes.  We have a 120 watt unit here that you should be able to run at least 6 pairs of speakers.  Can I write you up for one?"

I ran up to the woman and said, "Excuse me, but I have about 30 years experience in audio engineering and, obviously, this person is only interested in selling you a new stereo.  If you did what he said, there is a good possibility that you would have a fire on your hands.  I suggest that you run, do not walk, to the nearest exit and find an audio specialty store who will sell you a speaker switching box with overload protection."

Fortunately, the woman took my advice.  Unfortunately, the salesperson called security and I was physically thrown out of the store.

One week later, I saw the same salesperson selling shoes in the same mall.   This goes to prove that a sales person in a mass marketer is nothing more than that -- a salesperson.  Yesterday s/he could have been selling shoes, tomorrow s/he could be selling watches or dresses.  If you need advice on an audio problem (or just a question about the technical properties of a piece of equipment) go to an audio specialty shop NOT a mass marketer -- or, ask me.

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How Do I Ask a Question?

Just click the Feedback button below. 

I will answer almost any Audio question.  What I will not answer is questions like "What do you think of  this company or their products?" -or- "What is the best (fill in the blank)?"

One word of warning, though: my area of expertise is in home (including home theater) and professional audio (i.e., pro recording, pro playback, or pro sound reinforcement). I am somewhat deficient in the very specialized area of automotive audio and, in most cases, the problems cannot be diagnosed without being able to actively view the situation and installation. I will try my best to be able to give you some advice, but, the advice may be to see a good professional car audio installer.

Guidelines

Be sure to include the following information:

1. Your name (I hate to call people "Hey you!");
2. Your e-mail address (so I can answer you, of course!). For some reason, there are people recently who have filled out the Feedback form without putting their email address where it is indicated. Then I get a second Feedback form chiding me for not answering. I hereby apologize for all the notes that I can't answer because you do not include your email address...I'm sorry that you are an idiot;
3. The type of equipment you are asking about in the subject line;
4. All the other equipment in question and the technical info about each;
   1. The impedance of all the equipment in question (amps, speakers, etc. - these can be found in your user manuals).
   2. The distance between the speakers and the amplifier (if applicable).
   3. Any other information you feel is necessary.
5. The area in which you live (in case I have to recommend a dealer for you);
6. Any deadline for the needed information.
7. If you will allow me to use your name or e-mail address if I answer you publicly (that is, in the FAQ section below).

I will answer you by e-mail as soon as my schedule allows and those questions that should be in the FAQs below will be added at the next update.

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"Get'cha Audio Answers Here!"

This One Is Just Too Good!

Today (2/25/2006), this exchange took place. I have left off the name and email address of the questioner to protect him from his friends' rebuking him for his actions. I have cut and pasted the questions exactly as he sent them.

The email read:

i was installing a cd player this morning in my 92 camry everything was going fine after i wired everything and turned the radio on then the cd player was working fine but i hadn't put electrical tapes on the wires and they sort of collided and there was a spark and everything went out after that nothing works now not even my security system. please help me with this. thank you

My answer:

This is a big oops.

Just the fact that you even tried anything without protecting bare wires tells me that you should go no further.

Take your car to a qualified repair shop (in fact, go to Mr. Goodwrench) immediately after disconnecting all those wires. Check the fuses, if you want, but there is too much that could have been damaged by the shortcut that you took.

Sorry about that, but, this is a case of "leave it to a professional".

Thanks for writing,

The Audio Expert

He wrote back:

helo thanx for the reply but is there any fuse for the security system or something anyehere. i checked the fuse in the car there was one damaged i replaced it and i put the factory cassette player back and it didn't work. so did i blow the wiring in the car which caused the security system and everything to go out. what could be damaged. thank you

My answer to this:

It is entirely possible that you have done serious damage to the electrical system of your car. As I stated on my website, I am not as well versed in the very specialized field of automotive audio as I am in professional, studio or home theater audio. Therefore, I will not be responsible for giving you any advice other than the following:

Unfortunately, there is no way to be gentle with this.

Do not attempt anything else on your own. Go to a professional to repair whatever damage you have done, before a couple of hundred dollar cost becomes a couple of thousand dollar cost (or a total loss on the car).

"Hi Audio Expert. 

I have just installed a pair of 6x9 200w speakers in my back car shelf. Now, I'm running it of a standard cassette deck which I'm sure under powers them. I do have plans to build the system up. 

The speakers sound great, but when I really turn them up they sound very distorted. I was wondering if it was due to the tape deck or perhaps the wiring. It must be difficult to diagnose, but any comments would be appreciated.

Bart


Hi Bart,

What you are hearing is "headroom" distortion. You are asking the amplifier in the head unit to supply more sound than it is capable of. (How's that for great grammar?)

Let's say it is a 10 watt amp and you have it turned up so that the mids and highs are demanding 5 watts and the bass is trying to squeeze another 8 watts out of it, that leaves 3 watts that can't be achieved. This now "tables off" or "squares" the top of the wave form, causing the speaker cone to jerk back and forth violently.

When I was a demonstrator for a large speaker company, I would freak out store owners by showing them how a speaker rated at 100 watts could be blown by a 30 watt amp (I would just force the effect that you are getting from your car stereo). This would prove, once and for all, that more speakers are destroyed by under-powering than by over-powering.  

As soon as you can add some respectable amplification to your unit, the better. 

Thanks for writing.

---

Audio Expert- My name is Kevin (last name and address omitted), and here's the problem as of now:
    I've acquired a like-new (brand name) 800 watt (200w by 4 channels, 2 ohm stable) amplifier from a friend, who said it was in good working condition. I purchased an amplifier wiring kit from (electronics chain), which included (among other things) 10awg power wire, and small gauge blue amp remote wire. I wired the amp to my speakers (correctly), connected the pre-amp outputs from the source deck to the same on the amp (RCA plug connections, no troubles there) and connected the blue "amp rem .4A" labeled wire to the "rem" terminal on the amp itself (terminal located between the B+ and Grnd labeled terminals).
    OK, so it's all good, with just the power wires left to go... there's the problem, whenever I connect the Grnd to a ground location, and connect the B+ to the positive side of the battery, it (the pos. terminal I am touching to the bat.) throws sparks. It once blew the fuse (30A) in the amp, but has never blown the 30A in-line fuse. suspected problems are the remote wire, or perhaps some internal problems with the amp. If you can point out what's wrong here, or give me a generic guideline of how to do this right, please E-mail me. If so desired, any of this may be posted on your web page, and I ask that you respond with all convenient speed. Thank you."

Hi, Kevin,
    Common procedure with an used auto amp is to have it "bench tested" before installing it (or better yet, before purchasing it), due to the fact that MOST used auto sound products are sold used for one (and only one) reason -- they don't work anymore.
    My first advice to you is to remove the amp from the circuit totally and make sure that all the existing components are still operating correctly. (Use a volt meter to make sure that the remote trigger from the head unit is operating as it is intended.)

Bench Test Procedure

 
    Next, using a portable CD player and a bench top power supply (or an extra car battery), hook up a pair of speakers (or two, in your case) to the amp - then the variable (headphone) output from the player -- finally, twist the trigger and the B+ leads together to the supply (battery) and lastly, the ground to the B- supply (always connect the ground LAST). Make sure the volume on the CD player is all the way down (for obvious reasons) and play a CD. Slowly turn the volume up to make sure the amp operates "as advertised".

    Now that you are sure that all is working as it is supposed to, you can install the used amp. It is SUGGESTED (although not always practical) that the ground wire from the battery be disconnected before any electrical installation is done (you CAN'T do this if there is any volatile memory device in your car -- check the manual!). Then connect all the wires as per the above instructions with the notable exception that the trigger and the B+ must now be separated. The B+ wire is to go DIRECTLY to the battery with an in-line fuse within 12 inches of the battery terminal. The B- (ground) is connected to a good ground on your car AS CLOSE AS POSSIBLE to the amps location (be sure that there is enough BARE METAL, meaning NO PAINT, where you ground it).
    Now for the fun. The ONLY ground your chassis has is a piece of braiding that connects the engine block with the chassis itself (the cable from the battery, in most cases, goes directly to the engine block). The block is insulated from the chassis by the rubber composition engine mounts and IF this strapping is compromised, you have a difference in ground potential between the battery ground and the chassis ground. IN MY EXPERIENCE it is this fault that causes 80% of the problems with auto sound installations (including MOST engine whine). If the braid IS compromised, it HAS to be replaced. The other main cause of engine whine in an audio installation is running the signal (RCA) cables parallel to a power (+12v) cable.

Follow-up

    Unfortunately, Kevin had hooked all of this up to his car system before he wrote me to find out the proper procedure. I quote him:

    "I followed your instructions for hook-up (without having it bench tested), and it made my source deck smoke, so something's very wrong. I’ll have it professionally examined and installed by expert hands. Thanks again for all your help though."

"Mr. Expert,
        I have a really good receiver and decent speakers, but they sound terrible!  I have heard that the shape of the room has a lot to do with the way a stereo sounds.  The highs are real nice and clear, but the bass seems muddy and lacks definition.  I have checked the phasing of the speakers (red is connected to red and black to black on both of them) and that is OK. What is wrong?"
-- name withheld

    After a couple of e-mails back and forth, our correspondent informed me that he is in a very long, thin room (30 feet by 10 feet).  He has the speakers along one of the 10 foot walls.  His major listening area is about 10 feet from the speakers (good placement, an equilateral triangle).  His receiver is on one of the side walls so that one speaker is 12 feet from the near speaker and 22 feet from the far speaker.  Now comes the big question -- how many feet and what kind (gauge) of speaker wire do you have going to each speaker?
    This is where his problem lies.  He had about 15 feet going to the near speaker and 25 to the far.  In a stereo installation, the speaker wires must be the same length to each speaker.  The bass signal is usually mixed equally in each speaker and the difference in length of wire could cause a small phase differential between the woofers!  I advised him to get a new 25 foot long piece of the same wire he was using (a good 16 gauge high quality speaker wire) and to use it to connect the near speaker, coiling up the excess in a place where it was not too unsightly.  He called me on the phone to thank me.  The improvement was so dramatic (in his case) that he went out and bought 10 new CDs!

More to come.

    I will place more answers here as questions get asked.  Remember, if you don't want your name mentioned, let me know in your e-mail and you will remain anonymous.  

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