mgiang7

hmm this topic will most likely cause some heated opinions but i need some ideas.

i've got speakers in my car that are rated for 80RMS/160MAX all around (focals up front, phoenix gold in back). i'm feeding them about 50RMS right now and I'm thinking about swapping in a higher rated amp (partly because i'm curious/partly because i want a different amp). question is how much is too much to give them 100RMS? 125RMS?

what should i be careful of so i don't overdrive my speakers?

MacGyver

Yep, you're opening a can of worms on this one...

BUT, I think if you stick with the basic facts, you'll be OK. Your speakers are rated for 80W RMS, so that should tell you not to run them at anything much heavier than that. Yes, they may comfortably accept 90, or even 100W, but why would you chance it? Just buy more powerful speakers if you need to run that much power through them. These are common sense things, so here shouldn't be much argument there...it gives you a suggested rating, so follow it.

Second, if your amp is rated 50W RMS, do you think you're actually using that much power? No likely, unless you have the gain turned all of the way up, and you have the volume all of the way up. So, from that standpoint, I would probably get an amp that runs 100W RMS comfortably, turn the gain down a bit, and feel safe knowing that when I turn up the volume I may be pushing the suggested limits of the speaker without overtaxing it, and I'm not bringing the amp to its clipping limits.

Hope that helps...

mgiang7

thanks mac, that was pretty tame

i should add that i'm running my current amp at about 1/4 gain, and tend to listen at about volume 8-10 on my alpine head (max i think is 25), so i'm not driving it that hard.

but like you said, it'd be nice to get a 100RMS and then turn the gains down to zero. and i know it's doubtful that i'll hear the difference, i just want a new amp i guess too. thanks for the tips, i'll keep em in mind as i shop around.

of course the other gotcha, is i noticed that a lot of the nicer amps that are advertised at 100RMS tend to come out higher on the birthsheet (110-115), so i have to watch out for that too!

SC_Highlander

A 100W amp with the gains set conservatively should be fine. Remember, it's only going to put out the full power when you crank up the volume. Keep it at a reasonable level and turn it down immediately if you hear distortion, and you should be fine.

PJK3

lurker here...

to give some sort of credibility to my comments, i have over 10 years of professional sound experience, as well as many years of audiophile level experience in sound and installation, plus a background in car stereo installs as a hobby...

this could be a hot topic, but my intentions aren't to flame...

as a general rule of thumb, it is far better to slightly overpower speakers than to underpower speakers. generally, speaker damage is not done by over driving speakers, but occurs instead when an amp is pushed close to or into it's clipping zone (ie. it runs out of headroom) and sends distorted power to your speakers.
Like those above me have stated, having some excess power available assures that you do not run into the higher levels of your dynamic headroom, which keeps your sound clean and reduces the chances of distortion. over the years i have driven speakers with amplifiers that were far above the speaker's rated capabilities and have had no problems, but this is done with great care, knowledge, planning, etc. i have never blown a speaker unintentionally by overpowering it. understand however, that i 'm not recommending that you go out and over power your speakers, but i am just trying to make a point.
i have however seen countless speakers destroyed by having poor quality or clipping amplifiers sending distortion to speakers that were rated higher than the amplifiers. the quality of the power supplied is critical to the longevity of your speakers, and more importantly it will greatly improve the quality of the sound you hear at the volume levels you desire.
i am not a SPL kind of guy, but focus instead on sound quality. good clean power (preferrably from a high current amplifier) will provide a pleasant listening experience at just about any level that the average listener might want.

i just googled up this article, but it has a lot of good info on this topic, even if it is part of a sales pitch.
i also googled up this articlewhich goes into much more detail regarding clipping and how it works. once again, tolerate the sales pitch

in summary, if you're not pushing your current amplifier into distortion when listening to your music at its loudest during the loudest peaks, you may not need more power. distortion comes in mostly at the very top of your amp's dynamic headroom, and if you're not going into that zone, you should be safe.
if you are hearing distortion or just want more volume capability, peace of mind, dynamic range, or just a new amp - as a good novice standard, i'd suggest you try to stay with an amp that has a max RMS below 125% window of your speaker's max RMS capabilities, which is roughly 100 watts RMS/ channel.

MacGyver

PJ,

You're points are well taken, but as I'm sure you will find if you do a search for my handle and other words like distortion, maximum power, etc., you'll see I'm a REAL stickler for proper definition. The one point you make that sticks in my craw is "it is far better to slightly overpower speakers than to underpower speakers".

I know what is MEANT by this statement, but most do not, and that's where the misinformation and danger comes in. By overpower you mean to provide an amp that can push the power you need without clipping. However, most uninitiated perceive this to mean they should ACTUALLY push 150W RMS through a 100W RMS rated speaker, and that's just plain bad.

A few of us out there have the proper equipment at home/shop to adjust a 200W RMS amp to output 100W RMS into a 100W RMS-rated speaker when listening at near-max volume. This allows for running an amp within its sweet spot, an admittedly good thing. However, most do not, and therefore blow speakers left and right, all the while claiming "But the guy told me I should overpower the speaker!" Most decent speakers can handle 10-20% (I've seen as high as 50%) more power than what they're rated for without issue...this gives the company breathing room for warranty work...if you blew it, you most likely WAY overpowered it.

I agree with your rule of thumb 125% window....an adequate measure to power your speaker the way it should be powered without going beyond the amp's sweet spot and without dropping cash on extra wattage that won't be used.

I suppose the most amusing point is when so-called audiophiles claim "I'm putting 300W into this 100W speaker and it sounds great!" What they are failing to notice is that the gain is turned down to 50% and they never turn it up to full volume. So, their supposed 300W is actually around 100W, give or take.

PJK3

you are correct in clarifying this... whether the gain is adjusted directly at the amp or controlled by a pre-amp type adjustment (ie, volume, source level control, board, etc.), thus keeping the amp out of it's peak zone, it does need to be controlled. it takes a lot of power at high volumes to really trash a speaker (i said i never UN-intentionally blew one ), but you can damage one much easier than most people realize. i did place limits quantifying how much overpowering is allowable by stating a 'slight overpowering' and by defining a reasonable window of allowable upper tolerance, but restating it is never a bad thing. regretfully, i do not have any specific equipment for properly setting gains outside of my own ears, and my experience, so communicating how to listen and determine the onset of clipping or overdriven distortion is difficult to convey in this medium... (yes, i realize the human ear is imprecise for this, but you always dial the gain down a smidge to cover for that...)

lol, i've been down that road before... sigh. "You put that speaker on WHAT AMP!?!"

still, i've found that the 125% window is typically a nice zone to point people to(especially since the assortment of amps to speakers rarely match in specifications) since it is usually well within the fudge zone manufacturers give and still provides for enough headroom for clean dynamic peaks...

yeah -- i used to love this one myself. years ago during my school years i used to do the retail thing for home audio. we used to get guys in there all the time "NEEEEDDDING" 300 watt per channel amplifiers for their home or cars. i'd love to bring them into our sound room where we had a really nice Onkyo Integra power block amp... it had the especially interesting feature of having an old style VU meter for wattage on the front. i'd love to crank that thing up on some nice medium sensitivity speakers and get these guys to estimate 'how much wattage they were hearing'. of course, that means nothing, but when you'd get it loud and they'd guess 200 or something, it was always fun to show them the little VU's jumping up to 30 or 50 or so, turn it all off, explain to them the basics of power, headroom, dynamic range, and watch them happily leave with an amplifier that really meets their needs.

regarding you're disposition towards accuracy, i don't have to do any searching... i'm well aware of your desire to be precise. i'm a very regular lurker... (who is praying and hoping for an S2k purchase in the next month or so...) i'm also an engineer (Mechanical, but no masters) as well, and know the routine for being accurate. but, as you mention, sometimes bringing things down to laymans terms can mean a loss of accuracy.

Philip

mgiang7

hmm very civil discussion

since i have your ears, can anyone give me insight to why an amp from rockford and an amp from kicker (both class a/b) both rated at about the same RMS wattage can be so different in size? the rockford i found is about 14 inches wide, the kicker is 22! i've never looked inside one so i'm curious to what heck all that extra space is needed for? cooling? extra components?

PJK3, i lurked here for over a year before registering, and even then i ended up not buying an S2K, but i still hang out here, good info to be found!

PJK3

i own a Kicker ZR240 for my sub amp in my current vehicle. i'm shooting from memory here, but while the amp is alledgedly rated for 240 watts RMS into a bridged 4 ohm load, i seem to recall my birth sheet actually listed specs closer to (if not more than) 300 watts RMS. i bought the amp a year or so ago, so i'm not 100% sure, but it did stick in my mind since it was such a large variance from the official specs. i've also installed a few Rockford Fosgate amps for friends over the years, and the birth sheets usually reflected very close to what the amp was rated for. however, you can't just go on this example as my amp is a very limited statistical sample.

for the most part, i can really only speculate on the 'why' for the size and weight differential, but typically the difference is a result of larger (and usually higher quality) power supply capacitors, transformers, and other internal components. i know my Kicker has much better cooling capabilities than the Rockfords my friends have used. I also typically pursue high current amps over high voltage amps, and remember reading a couple reviews of the Kicker amps where they showed it to have notably higher current draws compared to several other amps (including if i recall correctly, the Rockfords). the real interesting amp that i own powers my highs and is an Adcom 4304 (4x30watt) amp. it is actually as large as my ZR240 and only supplies 1/2 the wattage of the Kicker under a 4 ohm load. but ooohh does it sound sweet.

i am very fond of my Kicker amp as it always seems to have oodles of clean power available at any levels i demand of it, plus it offers a lot of flexibility and will handle low impedance loads. but while i do like my ZR amp - i've not been impressed with Kicker's new KX amplifiers. they are not stable down into the low load ranges that the ZR's were capable of and they don't quite have the same sound quality either (but that is a subjective evaluation). they almost seem like more of a replacement for Kicker's IX line than anything else.

and mgiang7 - thanks for the welcome... i've been lurking here for about a year now, saving and waiting for the time to come when i could get a S2000...

mgiang7

i was going to ask about the KX kicker amps, i had my suspicions that the new KX line wasn't as nice as the ZR series. it's getting hard to find a "gem" of an amp. it looks like a few years ago the rockfords, kickers, hifonics were a golden age. i keep reading that they were all better then they are now.

any hints on that kinda of quality today? arc audio? zapco? i'm not looking to spend insane amounts of money for one, but at the same time a few hundred is fine. i just want an amp that i'll pretty much keep forever--something i don't see in the latest rockfords of today (as opposed to a few years ago) for example.