Head unit vs. amp for DB650's

The Illadelph

I have an integra with 6.5's all the way around and wanted to replace all 4 speakers so I went with the Polk db650's. I am running a Kenwood 528 head unit which says 50x4 but is most likely like what? 10 rms tops? My question is if I get an amp how much power should I put into each speaker without blowing them? Because I may be imagining things but it seems like the bass from the head unit is pushing the limits of the speakers right now. It seems like if they had an amp to them they would just blow out of the frame. Of course I am a novice and have no clue what I am talking about so this is why I am here. any help would be greatly appreciated.


also: would an amp make that big of a difference in sound?

skydeaner

Ok here's about how it's gonna go...
That kenwood is rated to put out 22 watts to all 4 chanels rms power with less than 1%thd (which is audible distortion). That rating is taken at 14.4v, so it is probably going to be more around 18 watts. In the manual for the head unit it states that there is a signal to noise ratio of 105db measured at 1khz. The measuring at 1khz is going to be the first problem, no music is just a 1khz test tone, so the s/n ratio is going to be lower just because of that. Not to mention they put this statement in the cd player section so it obviously wasn't measured at full rms output so it will probably be closer to 90 than 105.

now lets take alpine's smallest 4 channel the MRP-F240:
Again measurements are taken at 14.4v and that just makes me want to puke. But it redeems itself with accurate measurements at that voltage. The signal to noise ratio is 100db measured with channels fully driven 20hz to 20khz. So no matter what you are listening to you can expect 100db s/n ratio.. The thd is also measured with channels fully driven 20hz to 20khz, at .08% and it total with those numbers it puts out 40x4rms.

Now that makes the deck fall behind really bad and I am sure anyone would notice the difference between the two. It puts out half the power with over 12 times the distortion, s/n ratio isn't really even comparable because the kenwood doesn't state theirs accurately but you can bet the sn ratio on the deck is bad enough to bring vomit to ones mouth.

All in all, will it make a big difference in sound? Absolutely, it will be like night and day. I personally guaruntee you will notice the difference. Also the part about the speakers being pushed to their max. The cones could be reaching their x-max even with the 20 watts with a lot of bass heavy music. The good thing about the amp is that you have the option of turning on the high pass crossover at say about 80hz and cutting all those bass frequencies and then running a sub. Without those frequencies being cut out though I doubt the db650's will ever reach their rated 60wrms, unless you are listening to some kind of music without bass.

MacLeod

Youre right that the head unit is making about 10 RMS per channel in real world power. Also the distortion youre hearing is not from the speaker being overpowered but rather from the head unit running out of clean power and sendign a distorted signal. The head unit is far to weak to ever hurt those DB's.

Now the DB's are rated at 60 watts RMS power handling so thats the amount you should shoot for. As for what amp to go with it depends on how much youre willing to spend. The Alpine mentioned above is an excellent amp and can be had for pretty cheap.

Another good budget choice would be this Profile 60x4 model for $130. It will be a good match for those speakers.

Adding an amp will give you more power which will reproduce lower frequencies better and more realistic and will increase overall SQ substantially.

If youre just wanting some tunes to listen to while you drive to work then you probably could get by without an amp but if youre really into music and want it to sound its best, an amp is practically a necessity.

cam5860

Do me a favor just go ahead and put a amp on those db's. After you hear the difference it makes, you'll be saying to yourself damn i never knew speakers could sound this good.

Greg Peters

I have been running the db650s for a good while, first off head unit power (a purported 60x4 watts max) and amplified as well. The db's do a fine job at moderate volume levels and will even play pretty low for a 6 1/2" speaker, but they do tend to break up a bit trying to reproduce the lower frequencies when run off the head unit at higher volume levels. The tweeters can also get kind of screechy when the head unit's internal amp is driven into clipping (by working so hard trying to play the lower notes). This doesn't do your speakers any favors in the long term.

If you make sure your speakers are sealed up good and tight in their mounting locations, with the mounting surfaces damped with something like Dynamat, and they are crossed over at a reasonable frequency, the dbs will do pretty well until you decide to put 40-80 watts amplification to them. They are rated at 60w continuous power and 180w maximum. The 80 watt figure is not unreasonable for these speakers, as they will not likely see the full rated power at normal listening levels (the db series are very efficient, and at full volume would likely be too much for your ears anyway).

Should you decide to put a quality external amplifier to them, you could try an experiment and run them full range at a very moderate listening level- you would be amazed at how much louder and cleaner they sound, and how much of the lower frequency information the db's can actually reproduce. It will almost seem like someone hid a small sub in your car comparatively, and the transients in your music will have more impact as well- as in pushing enough air to make your pant leg move.

A properly installed amplifier will not clip the signal from your head unit unless pushed way too hard, and will actually do a much better job of keeping the speaker cones under control than your head unit's internal amp has done for you. At modest listening levels, I have had my db650s perform well crossed over at (HPF) 63hz. I currently have mine crossed over at 80hz and they can play quite loud without any distortion at all.

If you plan on running a subwoofer, the dbs can play low enough to allow you to set your sub's LPF in the 60-80hz range and keep your bass image "up front" where it blends in with your front stage, not sounding like it's all coming from the hatch area of your car.

The db650s are very good for the money, and doing them justice with a decent amplifier will not dissapoint. The bottom-line Alpine amplifiers are also pretty good for the money (and I believe 2ohm stable), and the V12 series are worth the extra if you are looking to keep them for your next upgrade.

The Illadelph

Thanks for the help guys and Merry Christmas/Happy Holidays!

MacLeod

Back atcha

The Illadelph

now lets take alpine's smallest 4 channel the MRP-F240:
Again measurements are taken at 14.4v and that just makes me want to puke. But it redeems itself with accurate measurements at that voltage. The signal to noise ratio is 100db measured with channels fully driven 20hz to 20khz. So no matter what you are listening to you can expect 100db s/n ratio.. The thd is also measured with channels fully driven 20hz to 20khz, at .08% and it total with those numbers it puts out 40x4rms.


I just wanted to come back and thank you for this suggestion. I took your advice and got the Alpine MRP-F240 to power the DB650's and wow. Thanks man. What a friggin difference.

1996blackmax

You can never go wrong with properly powering your speakers. Now they are getting a good amount of clean power.

Red230SX

MacLeod wrote:

The head unit is far to weak to ever hurt those DB's.

I don't know if I would go as far as to say it can't hurt them. When an amp
clips it's sending a square wave to the speaker. Speakers don't like square waves.

Actually, Voice Coils do not like square waves. When the cone is "hanging" at
the peak and valley of the square wave the coil is not being cooled and will
burn out (even thought it's receiving less than the RMS it's rated to handle).

Clipping is bad.. More power is far less destructful than too little, as has been
my experiance.

MacLeod

Nope.

There are only 2 things that will kill a speaker:

1- Building up more heat than the voice coil can dissipate (i.e. too much power)
2- Pushing the speaker beyond the limits of its suspension (i.e. too much power)

So basically, short of jabbing a screw driver thru the cone, you can only kill a speaker by overpowering it.

A speaker can handle any shape of wave or any amount of distortion as long as its within its power handling capabilities.

When an amp clips it sends out a signel usually double its normal output as its limited only by input voltage. In the case of a head unit making 12 watts, a fully clipped signal wont be more than 30 watts at the most. And while that 30 watts will be severely distorted its well within the 60 watt handling capability of the DB's.

The reason people associate underpowering with hurting speakers is that most people would consider underpowering those DB's by hooking up a 40 watt amp to them. So with this smaller amp youre more likely to push the amp into clipping by cranking the volume too much and when that happens the amp cranks out about 85+ watts and thats what kills the speaker.

Same with clean power. You take those same DB's and hook up a 150 watt amp to them and crank the volume up. It doesnt matter that the signal will be as clean and pure as the wind driven snow, its still gonna kill it.

Red230SX

MacLeod wrote:

Nope.

There are only 2 things that will kill a speaker:

1- Building up more heat than the voice coil can dissipate (i.e. too much power)
2- Pushing the speaker beyond the limits of its suspension (i.e. too much power)

So basically, short of jabbing a screw driver thru the cone, you can only kill a speaker by overpowering it.

A speaker can handle any shape of wave or any amount of distortion as long as its within its power handling capabilities.

When an amp clips it sends out a signel usually double its normal output as its limited only by input voltage. In the case of a head unit making 12 watts, a fully clipped signal wont be more than 30 watts at the most. And while that 30 watts will be severely distorted its well within the 60 watt handling capability of the DB's.

The reason people associate underpowering with hurting speakers is that most people would consider underpowering those DB's by hooking up a 40 watt amp to them. So with this smaller amp youre more likely to push the amp into clipping by cranking the volume too much and when that happens the amp cranks out about 85+ watts and thats what kills the speaker.

Same with clean power. You take those same DB's and hook up a 150 watt amp to them and crank the volume up. It doesnt matter that the signal will be as clean and pure as the wind driven snow, its still gonna kill it.

I will have to agree to disagree with you. I dabble in full range home speaker
building, I mess around with electronics a bit (certainly no EE but I have lots
of friends who are) I hang around with guys who either manufacture thier
own drivers or use the best top tier components money can buy.

It's been tested and it's been proven that square waves cause the damage.
A full range (or more accurtely wide range, since I know of no single driver
that is truly full range) can not reproduce a square wave. It causes the voice
coil to hang at each end of linear travel long enough for the coil to overheat
(lack of cooling) and as soon as your shelac melts you are done you have a
dead short and it doesn't matter if it ever got within 1/10th of the suspension
or motor systems Xmax or Xsus limits.

Of course too much power can hurt a speaker, if you supply the voice coil
with more power than it can handle without being able to dissipate the heat
again it will melt down the shelac and cause a dead short. Or if you extend
the cone, suspension past it's Xsus you can rupture the surround and the
spider which will seperate the from the basket. But you ears give out first
unless you are nuts! (Yes I realize some people are nuts).

I just want to make it clear I wasn't trying to be ignorant towards you with
my response I was just posting my experiances with audio, I tinkered for a
while...

You should see my 2 channel mains I am working on 8.5' tall and weigh
about 600Lbs a pair :eek:

MacLeod

Take a 500 watt subwoofer and hook it up to a typical head unit. Then stick in some bass heavy rap or techno music and then crank it to max volume. That will be nothing but a pure, clipped, square, 10% distorted signal and it wont hurt the speaker at all.

Another test. Take a typical 9v batter and hook the positive terminal of the battery to the positive terminal of a speaker. This will make the speaker flex out and stay there for as long as you hold it to the 9v. Now this is a totally flat signal which is much worse than a sqaure wave. It wont hurt the speaker at all.

If the power of the clipped signal is below the power handling of the speaker, then it wont be pushed beyond the limits of the speakers suspension and will not damage the speaker at all.

A 50 watt, fully clipped signal will never damage a 100 watt speaker.
A 100 watt, pure and undistorted signal will damage a 50 watt speaker.

Red230SX

MacLeod wrote:

Another test. Take a typical 9v batter and hook the positive terminal of the battery to the positive terminal of a speaker.

A nine volt battery puts out how many amps?

Like I said above I respectfully agree to disagree that's all.. There are lots of
others I am in the loop with (far more knowledgeable than I) who share the
same viewpoint as I do. In fact one friend is an audio engineer for a concert
hall and does work on the side. A local buisness that he dealt with has a full
JBL studio horn setup and underpowered them, clipped them all night long and
eventually destroyed all the drivers. JBL does not warrant products which are
damaged from less that RMS power(Studio equipment).

It's all good though!

1996blackmax

I will go with not sending a 50 watt clipped signal to my 100 watt speaker. I have run more power to many of my subs with no issues, as well as my components. Heck even when Car Audio and Electronics tests subs, they hook them up to amps that are way over the RMS rating of the sub. I do not go way over, but I would rather send a little clean power over the RMS rating than a clipped signal.

MacLeod

Doesnt matter how many amps the 9V puts out. Its below the speakers power handling limits so it will never hurt the speaker no matter how flat the wave is.

This whole misconception comes from people underpowering a 100 watt speaker with a 75 watt amp. When they push this amp too far it will clip and send out about 150 watts and the speaker blows so people assume it was the clipped signal that killed the speaker when in fact it is the 150 watts being fed to a speaker that can only handle 100 watts. And on the other hand you take a 150 watt amp for that 100 watt speaker and set the gains properly and it will not put out enough grunt to hurt the speaker. So the misconception is underpowering hurts speakers, overpowering does not. Thats why JBL wont warraty products underpowered because its more likely to clip the amp and kill it. Same reason why magazines use bigger amps.

Its really easy to prove this. Simply take your subwoofer and hook it up to a single channel of your head unit. Then crank the volume to max and feed it the latest Bass Mechanix CD. I can guarantee you that will be a clipped signal and it wont hurt that sub at all. Or, take one of your midranges and hook them up to your sub amp and play the same Bass Mechanix CD and {poof}.

Overpowering is the only thing that can kill a speaker (excluding manufacturing defects or physical damage) by the 2 ways mentioned eariler. When an amp clips, it sends out around double its power and then overpowers the speaker. A speaker doesnt care what shape the wave is. It can be a perfectly flat wave at 20% distortion (9V batter) but as long as its below the limits of the speaker it will never damage it.

Greg Peters

A couple of links that state JBL's case...


http://www.jblproservice.com/general_faq.htm

http://www.jblpro.com/pub/technote/lowpower.pdf


Regarding speakers we traditionally put into our cars, subs would be less likely to be harmed when driven by a severely clipped signal, as this usually results in greater harmonic distortion in the upper frequency range.

While a clipped signal reproduced by a subwoofer (that cannot realistically play the highest frequencies) does not sound pretty, it is not likely to harm the subwoofer if driven with low power.

Putting a clipped signal through a tweeter or coaxial with no crossover (or only a simple crossover) will have greater potential to do harm, due to the massive amounts of high frequency distortion produced (and corresponding driver overexcursion). Tweeters vibrate at many more cyles per second than subs and midranges, are more fragile by nature, and are the easiest to damage if overdriven. A quality crossover can mitigate damaging effects on the tweeter to a degree.

Powering a midrange speaker with a sub amplifier would send those high powered subwoofer-specific frequencies to a speaker incapable of properly reproducing those notes, also causing overexcursion, overheating, and untimely speaker death for all of the above reasons.


Most car audio enthusiasts would "turn it down" long before damage occurs from clipping, because we wouldn't tolerate the sound of speakers distorting at a high volume for long enough for the speakers to blow- common sense. Some people who crank their music to this point do not know any better, and damage their equipment out of ignorance. The same people go on to give great products bad reviews online- "I powered these with my Pyramid 1000 watt amp and they could not take real power..." etc. without realizing that such an amp clips easily and puts out nowhere near respectable THD at reported "power" output.

In a textbook sort of way, both MacLeod and Red230SX 's arguments are correct. There are points where underpowering or overpowering a given speaker can do damage. Overpowered speakers do not give you as much warning that damage is being done until it's too late. Improperly damped woofers (due to enclosure) may shake themselves apart with clipped signals or too much power. If powered wisely and used wisely, you can deviate from recommended power ratings for speakers (within reason) without causing ill effects. The ratings are generalities, a margin of error where the speaker will perform well and last longest in the hands of the average user.

Since most people on this forum own Polk Audio products, it would be interesting to hear Polk's official take on the subject- from a customer service and product warranty perspective...

Red230SX

Greg Peters wrote:

A couple of links that state JBL's case...


http://www.jblproservice.com/general_faq.htm

http://www.jblpro.com/pub/technote/lowpower.pdf


Regarding speakers we traditionally put into our cars, subs would be less likely to be harmed when driven by a severely clipped signal, as this usually results in greater harmonic distortion in the upper frequency range.

While a clipped signal reproduced by a subwoofer (that cannot realistically play the highest frequencies) does not sound pretty, it is not likely to harm the subwoofer if driven with low power.

Putting a clipped signal through a tweeter or coaxial with no crossover (or only a simple crossover) will have greater potential to do harm, due to the massive amounts of high frequency distortion produced (and corresponding driver overexcursion). Tweeters vibrate at many more cyles per second than subs and midranges, are more fragile by nature, and are the easiest to damage if overdriven. A quality crossover can mitigate damaging effects on the tweeter to a degree.

Powering a midrange speaker with a sub amplifier would send those high powered subwoofer-specific frequencies to a speaker incapable of properly reproducing those notes, also causing overexcursion, overheating, and untimely speaker death for all of the above reasons.


Most car audio enthusiasts would "turn it down" long before damage occurs from clipping, because we wouldn't tolerate the sound of speakers distorting at a high volume for long enough for the speakers to blow- common sense. Some people who crank their music to this point do not know any better, and damage their equipment out of ignorance. The same people go on to give great products bad reviews online- "I powered these with my Pyramid 1000 watt amp and they could not take real power..." etc. without realizing that such an amp clips easily and puts out nowhere near respectable THD at reported "power" output.

In a textbook sort of way, both MacLeod and Red230SX 's arguments are correct. There are points where underpowering or overpowering a given speaker can do damage. Overpowered speakers do not give you as much warning that damage is being done until it's too late. Improperly damped woofers (due to enclosure) may shake themselves apart with clipped signals or too much power. If powered wisely and used wisely, you can deviate from recommended power ratings for speakers (within reason) without causing ill effects. The ratings are generalities, a margin of error where the speaker will perform well and last longest in the hands of the average user.

Since most people on this forum own Polk Audio products, it would be interesting to hear Polk's official take on the subject- from a customer service and product warranty perspective...

Greg,

Awesome reply! You put it into words better than I did!

I was about to respond that the issue is more to do with tweeters and smaller
midrange drivers. Tweeters in particular are easy to fry.

I have had the unfortunate experiance of frying the diamond hardened titanium
domes in my Home Theater Left and Right mains when I was fooling around
with a Behringer Tube-Q and I had the volume down near zero and pulled
one of the cables out to switch it around and caused a massive high frequency
feedback loop. Literally 1 second later the tweeters were toast. That was
all it took.... $300 later (expensive little tweets) I was good to go, and I will
not make that mistake again.


These forums are very good! It's nice when two or three people can exhange
viewpoints without an argument! Absolutely awesome.

MacLeod

JBLpro.com wrote:

When an amplifier is overdriven, the contours are”clipped”off, producing a near square wave, having flat areas at the top and bottom limits, in which the average power approaches the peak power. When this occurs, up to twice the amplifier’s rated output can be delivered to the high frequency driver, which may not be capable of handling the abnormal load.

I was right! I was right! Neener neener!

I think we can all agree that its best to properly power your speakers without under or over powering them.

Red230SX

Mac,

We can certainly agree on that

1996blackmax

Finally