...mount an amp on the BACK of a subwoofer box?

That's what a guy at Best Buy told me today. Seems unlikely...wouldn't it interfere with the sub's bass?

I'm skeptical because the same guy was telling me what a great deal and "incredible" sound his Rockford Fosgate 501s were, at over double online prices and that I'd have to buy a $100 wiring kit plus a $100 cap.

To his credit, he at least didn't push any Sony amps.

 

That will not be a problem. Most amps have rubber grouments where the screws go through, but if not that should be fine. A lot of people do it that way.
Buy on line.
Don't need a cap!!

 

You won't have any problems with mounting an amp on the back of the sub box (with or without rubber grommets).

 

the only problem with that is if someone steals the box they get an amp too............................

 

If they are taking the box, they will find the amp anyway. This is from experiance!!!

 

OK, in that case can an amp mounted on the back of a sub box be put flat against the cabin wall, or would it need to have some clearance from the wall?

If it needs a little clearance from the wall, sounds like I'd need to be careful about ever having anything fall into that tiny space...

Would the sub need to be bolted down into the floor of the cabin, in this case, in order to keep it from moving? My sub feels very HEAVY already.

 

Definitely bolt the sub box down...you don't want it sliding around, or causing an annoying vibration.

 

DO MANY MANY people mount the amp to the boxes? YES

SHOULD they and is it the best choice? NO

if I came to your house befor you installed your amp and picked it up and began to shake the crap out of it you would probly proceed to try and kick my *** and tell me to be carful right??

well then why would you mount that same device to a box that will do FAR worse. also ANYTHING and everything you mound in or on a box changes the harmonics.

will you come across a problem?? maybe but most dont. but if you can find another place do it

 

Well, I was going to comment on this. I really wanted to. But I will hold my tongue for the moment.

 

When the woofer(s) moves in or out, the box flexes and therefore causes the sides of the box to vibrate. This vibration is transferred to the amplifier mounted to the box. All of the electrical components in the amplifier have mass. Inertia (an object in motion tends to stay in motion, an object at rest tends to stay at rest) tells them to stay at rest, the box vibration is trying to make them move. The energy from the box's vibration is transferred to the components through the electrical leads which are soldered into the circuit board. All of this will cause the components to break loose and therefore cause the amplifier to fail prematurely. Basically, the amplifier will commit suicide! :-) I'm not telling you this because someone told me it was bad. I've been repairing amplifiers since ~1985. Virtually every amplifier that's come into my shop with parts rattling around inside them have been mounted on the speaker box. It causes the legs of the semiconductors to break (which causes amplifier failure). It causes the capacitors to break off of the board (which can cause catastrophic amplifier failure). It causes solder joints to break on the semiconductors mounted to the heat sink. It causes transformer windings to grind into one another (which causes lots of smoke to pour out of your amplifier). People who repeatedly tell others to mount their amps on the speaker box because they've never had a problem remind me of people who drink and drive and say there's nothing wrong with it because they've never crashed their vehicle. Eventually, in both cases, problems will arise.

ref www.bcae1.com


comment all you like . please do!!

 

I am not saying it cant be done I’m saying that its irresponsible to advice someone that they will have no problems. when in fact it CAN cause the problems mentioned above and does.

 

ampresearch,

thanks...what you write makes a lot of sense. I didn't have a great feeling about doing that, didn't sound like a very good idea even though you are the first person from about 3 forums where I've posted this question who has such a strong negative opinion on it.

I was going to mount the amp on the rear cabin wall, but have to admit I liked the idea of being to remove the sub and amp in one easy step if I ever needed to---sometimes my unfortunate friends have to sit in the back! Oh well, now they'll have to lie in the trunk (I have a camper).

Just curious, since you've been repairing amps for so long...which brands have the most repairs, and which the least? How does PPI, Eclipse, Phoenix Gold, and Soundstream Rubicon compare in terms of reliability?

 

Ok, you guys pulled it out of me. First, if the enclosure is properly constructed vibration will be so minimal that you should not experience any trouble whatsoever. Second, I can agree that extreme vibration will in fact cause component seperation and result in ultimate failure of possibly additional components.

Let me briefly touch on a few points that support this information. All, electronic components utilized in any electronic circuit must undergo testing prior to it's use in consumer electronics. These tests include vibration, over voltage, under voltage, current and voltage spikes, and thermal tests to name a few. They are somewhat extensive and far exceed any condition said amp would endure if mounted to a well built enclosure.

Now notice that I have kind of stressed the well built enclosure aspect. The reason for this is that if it is well constructed the vibrations transferred to the amp casing would be minimal and very likely no greater than those experienced through the rigors of every day travel due to vibrations transmitted through the frame and body of a car. However, if you have a poorly built enclosure with inadequate internal bracing you can have flex up to 1/4" or more of the enclosure wall and yes this would cause failure.

Another point I would like to bring up is the shear numbers of home subwoofer cabinets that are built by numerous manufacturer's which contain an amplifier internally in the box or mounted in the enclosure itself. If the results of this mounting method resulted in high failure rates there would be a change in mounting methods instantly. Keep in mind that many of these home sub systems carry warranties 2-5 years in length.

Now, the most common reason for amp failure in car is incorrect installation or abuse of the amplifier past it's operational capabilities. I have personally repaired many of these amps and have seen the resulting damage. When I have seen components physically loose within a casing it has many times been caused from over voltage on a capacitor and the cap itself has exploded causing the casing to rattle inside the amp. In each case that I have seen this as an instance there have been tell tale signs of thermal limits being exceeded.

In short, my conclusion from past experience and education is that most cases of amp failure are caused by abuse or incorrect installation or a combination of both.

 

noticed i refferenced a site at the end of the post.

read this site you you will know more then 90 percent of the people working at your local shops.

that was a quote from a very popular site for techs . particularly newer techs. i myself have only been repairing electronics for about 10 years. .

I dont see just one brand more then the other due so the fact that there is a HUGE influx of people doing there own installs.like cgorris. so i see just about every brand. most highend amps if used to tehre specs and purpose live long lives. If i had to pick a brand though i would say that due to its recent popularity rockford comes in quite often. there stuff used to be the best around back in early 90's but in the recent years they have taken a huge back turn in quility IMO.

btw also like cgorris said IF people brace there boxs and such he is right you will greatly reduce the chances of damage to your equipment but unfortunatly MOST people slap four walls together and call it speaker box. when truth is they just build a box suited better for toys then speakers.

 

btw the original question here was is it safe to mount a amp on the back of a box. my answer still remains no if you have any other choice use it.

once again not saying it will cause problems just that it can. and if i told you its great idea then i would be giving a irresponsible answer.

If you have no choice then go for it but if theres a choice why make the one that MIGHT cause problems when you can chose the ones that wont