Question on amp wattage

[stevenk2]

I was going to post this in an existing thread about stereo upgrades, but thought it might get into the weeds a bit as far as that goes, plus it seemed like it deserved a thread of its' own. I was on Crutchfield's website in a chat with one of their techs yesterday, and we were discussing speaker upgrades (from my current OEM Polk DB652's). I had been looking at the possibility of upgrading to the JL MX series, but had some concerns about the price versus performance in relation to my DB652's. The subject came up about my amp, and the tech stated that my DB652's were great speakers already, they actually were rated to handle more power than the JL's I was looking at, and I just needed to provide sufficient power to them to realize their full potential. The amp I'm running is rated at 50W x 4; the DB652's are rated at 100W each. The tech said that I'd want an amp that could provide them each the full 100 watts they want/need (i.e. 100W x 4 channels), the theory being that instead of boosting the gain on a lower-powered amp and introducing distortion at higher levels, I'd be providing "clean" power/signal without overboosting using the gain control on the amp. Does that sound correct, or are the JL speakers truly a huge upgrade over the Polk's I currently have?

I know this thread could go a lot of different directions, but the main question would be per channel amp power versus speaker capacity, and how closely you want those to match for optimum sound quality at volume (i.e. higher volumes).

 

[Banditgrrr]

I've recently been going through the same dilemma. I also have 4 DB652's in the cabin and although they sound great powered by my Rockford Fosgate R400-4D (75x4 @ 4 ohms), I'm thinking I could get a little more power out of them by upgrading to a 100x4 amp. Keeping an eye on this thread to see what the experts here recommend.

 

[Mainah]

Speakers are rated in power handling, resistance, and efficiency. Taking just the power handling rating alone does not tell the whole story as to the decible output of the speaker. That does not even account for Polk being a bit agressive with their rating and JL being more reserved. I have zero doubt the the jl mx650 will be a bit louder, fuller, cleaner, and last longer than a polk db652. Is the perceived volume a huge difference once powered properly? A noticeable difference yes but I would not say huge. It sounds like the Crutchfiled rep was attempting to explain headroom or clipping, I am not sure which. A more powerful amp will help to a point. Tune it below clipping and below whatever power will start to melt down the speaker coil. 75x4 true rms, at 4 ohms, without clipping, and with 80hz high pass is plently going db652s. Oh yeah forget the max ratings and pay attention to rms when matching things up unless you are entering audio competitions or only listen to pitchy music.

The things that make the biggest difference are placement, surface area, power, excursion, response frequency, and speaker/amp quality roughly in that order. To increase surface area install bigger or more speakers. To increase power install a more powerful amp. To incrase excursion install better speakers. To improve response frequency install a sub woofer and remove the lows for the full ranges then send more power to the full ranges. To get better quality install higher quality components. To get the beat out of what you have or what you have upgraded, tune properly.

The number one thing to get more out of full ranges is to add an amp AND cut the low frequencies going to them, then send more clean power. The difference is amazing. Placement is very important. To fill in those lost lows add a sub. Good all in one powered subs are fairly cheap and dead simply to install if you dont want to get into installing another amp and cutting holes. After that more speakers and amps are needed to increase volume.

If it were me on a low fixed budget and I already had polk dbs I would start with a good amp with quality crossovers, add a sub and tune it all properly. If not happy go from there. I did eactly this and learned the hard way that while a good value I am not a fan of the Polks particularly with the silver color grills on the swim deck as they fade. The audio quality is quite good for the money though. To each thier own as I am on upgrade 4 and counting (who knows when I will finally stop). The nice part was I started with a robust power run and JL amps with future upgrades in mind. Each year it has felt like a new audio system in the boat.

 

[Banditgrrr]

@Mainah Your one post gave a better explanation than 3 hours of reading!!!! I'm tracking with what you said and doing the following:

1. Changing my DB652's from full range to high pass and continuing to push them with my Rockford Fosgate R400-4D @ 75x4 @ 4 ohms
2. Adding a Kicker CXA6001 amp and Kicker 44TCWC104 10" enclosed sub at 300W. Locating under the rear port side seat.
3. Tuning all 3 of my amps appropriately

@stevenk2 Not trying to hijack your thread but sounds like you and I are literally in the same boat! Let you know how adding an amp/sub and changing the DB652's to high pass work out.

 

[ralphsmithiii]

I had a written out reply but Mainah hit the high points. I can't see it under your name but are you boating in Fresh or Salt water?

Reason I ask, and maybe this does or doesn't help, but, the Polks are not Marine certified for salt water, only "salt-fog". The JL's are. So, if you think you're going to boat or do boat in any type of salt water, then it may be an easier decision than you think. Otherwise, the Polks if powered would only give you a better sound than what you have now, no doubt. Better than JL...probably not if all things being equal. If you just plug and play your JL's they could sound worse as their db per watt is 89 versus the 91 on the Polks. But they are beefy, WAY beefier than the Polks in terms of components, magnet, basket, etc.

 

[stevenk2]

Perfect - thank you, thank you for all of the info Mainah and Ralphsmithiii!!! That's the most detailed info that's specific to my questions than I've gotten anywhere else.

In regards to the question about fresh or salt water, I'm inland fresh water lakes and rivers only, so no worries with my current Polk speakers, but the info regarding the build quality on the JL's is good to know.

As I work on upgrading my system, my main question/concern is if brands like JL and Wet Sounds are worth the extra coin, and it sounds like they are. I don't mind spending the cash on them, but what I don't want to do is throw away money on gear that's not worth it (and with some of the JL's being 4x as expensive as my Polks are, it adds up in a hurry). And it sounds like just running out and getting a 4x100W amp to drive my Polks isn't the right answer either. I think for this season, I'll add a sub on a different channel, then split off the low frequencies to that, and continue to feed my Polks the higher frequencies and see what that sounds like.

Beyond that, I think my fall/winter project at the end of this season will be looking at upgrading my speakers and amp, potentially adding tower speakers as well - armed with the knowledge from this thread, it'll be much easier making intelligent purchase decisions.

 

[stevenk2]

Not trying to hijack your thread but sounds like you and I are literally in the same boat! Let you know how adding an amp/sub and changing the DB652's to high pass work out.

Not at all - I'll let you know how it sounds after I add my sub and adjust the amp settings. I'm hoping for some improved results - as I have it set up right now with no sub and the gain set to recommended levels (i.e. 80% volume on the head unit, then adjust gain just below distortion levels on the speakers), it doesn't sound so great at higher volumes. If I keep it around 80% volume, it's reasonably decent (quality varies based on the music type and such, of course), but I suspect once I strip out the lower frequencies and throw those onto the sub, I may end up being much happier with the quality at the higher volumes.

I'll have to take a look around on the forums and see where folks are mounting their subs. For right now, since this is only a temporary solution, I'm putting my sub in an enclosure and securing it behind the helm. Probably not the best for getting the sound out, but I don't want to go cutting holes in my boat without first being absolutely sure of where I want things (and/or of the exact equipment I'm going to end up with). Worst case, for this season I'll just open up the helm door when I want full effect. Heck, who knows, the cubby under the helm may end up being the perfect size and shape to act as a sub enclosure itself......…..

 

[Mainah]

I have frequently posted my disdain for the polks environmental ratings vs. performance. Keep in mind this in relation to perfection/JL. They are good sounding speakers and a great initial value. I have 4 pairs of polk mm 6.5 and two polk mm subs. After powering and tuning they sound awesome. The ones with silver grilles on swim deck have faded/yellowed way beyond what I think they should have. The low/mid bass is not all that I want (mu wants are unrealistic for an open environment like a boat) but for the money they are realky good. The rest in the cabin, particularly the black grills still look new. When pulling the polks on the swim deck to do other things the baskets and magnets still look good. Keep in kind my boat saw one week in the bahamas with no cover last year and the swim deck gets dipped in fresh water everytime I raise and lower my lift.

I may be a bit overly harsh on the polk speakers but that is somewhat influenced by my experience with the swim deck remote. Comparing a porchse 911 to a mtitizubihi eclipse would not be fair given their price classes so neither is polk db to jl m series. Both cars are fun to drive and both speakers will sound good. The difference once tuned properly comes down to wow vs. breathless. If I had new Porsche money I would have 4 top end Jl amps and all M series. Since I don’t, I use a bit of knowledge/skill and work within my budget to make the most of what my budget allows.

I don’t know where tuning to 80 percent of headunit came from. My method is to isolate the headunit to find where it clips, turn it down one notch and then tune the rest. I have great results in my truck and my boat doing this. My relatively low wattage stock truck door speakers sound like high end aftermarket when removing the low end and sending good power. A perfectly sized under rear seat sub box makes my single 10inch polk db sub sound like two when properly powered and tuned with a cheap over powered rockville amp (the crossovers suck but thankfully my headunit has digital ones built in). For about $500 my truck sounds like it has a $2k system in it. My boat is a similar story but it took a lot more work and money along with higher end components.

Can’t wait to read about the result you guys achieve.

 

[Banditgrrr]

Looks like I'll be delayed a little bit. I just connected my new Kicker mono amp to my head unit and I'm barely getting any sound out to my new sub. I have the Fusion MS-RA70 head unit and I connected the new amp to Zone 1 Sub and no sound. I then connected it to Zone 2 Sub and no sound. I connected it to the regular Zone 1 RCA's and I have a ton of bass. I've checked all the settings on the head unit and everything seems to be working fine. I don't really want to run an RCA splitter off Zone 1 because that defeats the purpose of having a sub volume control on the head unit. I guess I'll be calling Fusion tech support tomorrow to try and figure out why I can't get anything out of Sub Zone 1 and Sub Zone 2

 

[stevenk2]

I'm sure that the JL's and the other higher-end speakers are worth it, especially looking at the longer term. As you say, the Polks I have are a Mitsubishi Eclipse - I set my expectations accordingly. They'll do for now, then I'll work on a better investment for the long term starting next year.

The 80% head unit volume suggestion came from the manual I got with the amp, I'll probably play with the settings more once I get the system setup this weekend and see if I can tweak things using your method to get it just perfect. Again, I set my expectations accordingly based on the equipment I'll have - I fully expect to be way better than stock, but I'm also not expecting to get the performance out of my system like I hear from those high-end systems in the larger $250k ski/wake boats. I think once I get the sub and its' amp installed and start messing with the levels I'm going to be much happier than just pushing everything through the DB652's.

I'll post an update once I get everything installed this weekend.........….

 

[stevenk2]

Okay, I got the amp a couple days earlier than anticipated, and I had some time this evening to install it......…..holy crap, what a HUGE difference from the 4-channel one I pulled out! It amazes me how much better it sounds now with the separate channel for the sub (and with the sub attached and working now). I need to work on the tuning a bit now, but I ran out of time this evening, plus I didn't want to p off the neighbors at 11 PM on a weeknight. Before (with the 4-channel amp), I could crank it all the way up to 40 on my Clarion head unit - it would get loud (still bearable), but the DB652's wouldn't clip at the gain I'd set on the amp. It sounded just pretty alright (i.e. sound quality + volume level), I could live with it. But now with the 5-channel amp and the sub hooked up, I can only get to about 30 on the head unit before the DB652's start clipping, and it gets LOUD. If I keep the volume at around 20-25, it's still really loud, plus the sound quality is still really good. You can hear and feel the 8" sub pretty well too, even though I know a 10" (or larger) would probably move more air. I think this may be a consideration when I work on upgrading everything over the winter, but with where I'm placing it under the helm, 8" is all I can go for now due to space constraints.

I'll probably spend some more time this weekend on the tuning. I think it's probably going to be tricky balancing the low-pass filter built into the head unit versus the one on the amp, since you can't just bypass/disable the one on the head unit. If I'm remembering right, the head unit has three levels, 80, 120 and 160 Hz - I'm wondering if I should match the level of the amp, or should I set it higher or lower? Also, the head unit has a separate rear out channel as well, maybe I could connect the sub input of the amp to that instead, then the amp's LPF would handle it?

In regards to the adjustments on the amp, I have gain and high-pass filter dials for the front and rear channels; for the sub, I have gain, low-pass filter and bass boost. The gain dials for all of the channels don't have any numeric settings on them, but the high-pass filters on the front and rear channels go from 15 to 250 Hz; the sub's low-pass filter dial goes from 35 to 250 Hz. The bass boost dial for the sub goes from 0 to 12 dB. The documentation about tuning in the amp's manual leaves a little to be desired, so I'll either watch for some guidance on here, or start doing some searching online. Where I left things tonight, I was literally just playing it by ear and setting it to what I thought sounded good, but that's probably not the correct or very precise way to do it. Any specific advice here would be appreciated.

 

[Mainah]

A qaulity headunit with a lpf is a great thing. Without getting too deep on db/octave and phase distortion 99% of the time you don’t want to use a low pass of the headunit amd a low pass on the amp. Depeding on a few factors most times setting the amp to full pass (crossover off) is the way to go. This will be dependent on the sub and the octave rate of the headunit crossover but if at least 12 db/octave doing this there is far better becuase attentuating the frequency at a lower power level. 120hz at the headunit is the way I would go.

Bass boost on an amp is a finicky thing that should be used rarely IMO. Again not getting too deep setting this to flat is usually best. This is especially true is the headuint has a gain level for the for the sub or an eq for the sub frequencies.

For the full ranges 80hz highpass is the way to go. If the headunit has this built in as well again set the amp crossover to full pass and do that at the headunit instead. I may have missed it but what headunit to you have?

To get a better curve from the headunit gain ideally find where it clips turn it down a notch and then tune the amp gains below clipping (all after the the crossover settings in headunit and amp have been done). If no Oscope one way to do this is to play a test tone with a good phone app (I have tested f generator pro app against other apps on an oscope and it is by far the best at outputting the max clean signal from the phone) all full volume on the phone and app with speaker/amp loads disconnected from the headunit. Your headunit should v rms/pre out rating for the rca outs. Measure the ac voltage on the rca out as you turn up the head unit and when you are 10 percent under the rating (usually 2 to 4 volts) that is the max you will want to turn up the headunit also want to make sure that is under the rca input rating of the amp. If you do have a oscope or smd tool then that is the way to go.

Have fun and be careful with clipping as it starts before most people can hear it.

 

[stevenk2]

Thanks - I'll give all of that a try and see how good I can get it. Sounds like in a nutshell I'll set the crossover on the HU to 120Hz, turn the bass boost on the amp all the way down (and yes, my HU has a level setting for the sub, so I'll use that setting instead of the one on the amp), and then I'll play with the volume and gain settings on the HU and amp to get things where they should be.

Is there any trick to setting the gain on the amp for the sub, or is it basically the same deal as my 4 DB652's, just find where it clips then dial it back from there? Would it be preferable to adjust the levels for the sub with the HU or with the amp?

I have a 2019 Yamaha AR195, and the current stereo setup is with the Clarion GR10BT HU and XC2510 amp, four 6" Polk DB652's for the full ranges, and a single 8" Polk DB842DVC for the sub in an external enclosure. I originally purchased an XC2410 amp, but I wanted/needed the extra channel for the sub, so I returned that one and got the XC2510. My primary goals for this initial setup/upgrade were to find something that sounded better than stock that wasn't hugely expensive to do, also with the potential of reusing some of the components down the line. I think I've accomplished at least the first two goals with this upgrade, though I'm unsure to what extent I'll be able (or want) to reuse the amp and sub when I do my more extensive upgrade this winter. So far, I think this upgrade is a home run as far as performance versus stock without breaking the bank - it should perform well for us out on the water this season once I get it dialed in.

The only other concern is going to be powering a more extensively upgraded system as I redo things this coming winter - I'll likely need to look at adding a second battery to my boat. But that's a different topic that I think has been pretty well covered in other threads on the forum. From what I've read elsewhere, I should be fine with this current setup, so long as I'm not running the thing all day while the engine's off. We typically only stay at anchor for an hour or two before we're on the move again, and even with that, the stereo isn't running the entire time. That and I always keep my boat battery on a smart charger in the garage.

 

[Mainah]

Start with amp gains at ten o’oclock postion and adjust the hu before adjusting the amp. Looks like no hpf on the headunit so set the amp to 80hz highpass for the polks. Should sound great. Should be an awesome budget upgrade that will sound much better than the budget would indicate.

 

[stevenk2]

I don't see a way to disable the crossover for the sub on the amp, it's only adjustable from 35 to 250Hz. If I set the LPF for the sub on the HU to 120Hz, does that mean that's all that would ever make it to the amp? The theory being that I would just set the sub crossover on the amp to 120Hz or above, then it's just taking whatever sub output the HU throws at it (i.e. 120Hz) - correct me if I'm wrong on that though.

In other words, the crossover for the sub on the amp never comes into play, since the only frequencies ever making it to the sub from the HU would be 120Hz or below, correct?

 

[Mainah]

I don't see a way to disable the crossover for the sub on the amp, it's only adjustable from 35 to 250Hz. If I set the LPF for the sub on the HU to 120Hz, does that mean that's all that would ever make it to the amp? The theory being that I would just set the sub crossover on the amp to 120Hz or above, then it's just taking whatever sub output the HU throws at it (i.e. 120Hz) - correct me if I'm wrong on that though.

In other words, the crossover for the sub on the amp never comes into play, since the only frequencies ever making it to the sub from the HU would be 120Hz or below, correct?

Did not know that amp does not have switches for that like most. Two choices here. Set headunit to 120hx and amp to 250hz. The down side is going to be a bit of phase distortion that you probably won’t even hear, with the upside of being able to control more about the subwoofer from the hu. The second choice is to set the sub out to full which disables all of the the other sub features and set the amp to 120hz.

Oh yeah there is third choice that might work. Set both to 120 hz which will double the slope to 24db but possibly cause more distortion although with a sub likely won’t hear it. Worth a try for comparison against all three just remember to turn the gain down each time changing it and readjust back up accordingly.

 

[stevenk2]

Thanks - I'll try all three options and let everyone know what I come up with and what ends up sounding best.

 

[stevenk2]

Finished tuning the amp this weekend - the best sound came from setting the LPF on the amp to the max setting (250Hz) and setting the head unit to 120Hz; I also set the sub gain on the amp down to the lowest setting and up to 20 on the head unit, and turned down the bass boost to the lowest setting on the amp. So basically letting the head unit manage all of the output settings to the sub. Also set the HPF on the full-range speakers to about midway on the dials for both front and rear channels, guesstimating that sets them to about 80Hz, since there's no graduated markings on the dials on the amp. I ended up setting the gain on the full-range front and rear channels to about halfway (12 o'clock position) - found that gave me sufficient volume without clipping/distortion.

I did try matching the LPF of on the head unit and amp as you suggested (setting both to 120Hz), but I was hearing some weirdness going on at higher volumes when I did that. Not sure if that was just my ears or not, but it sounded better to me the other way, so I set the amp to 250Hz and the head unit to 120Hz and left it.

Thanks for all of the help and detailed explanations on all of this, Mainah! My system sounds really good now, I'm looking forward to getting on the water to test it out live.

 

[BrandonG]

I also have a 2019 AR195, I installed a pair of tower speakers and through doing so I believe I read that the Clarion headunit that comes in these boats only puts out 14w RMS? Seems like it would be a pretty big lack of power for the 4 Polk DB's?

I also realize I think I need a subwoofer as the music is just loud and has no low end bass at all.

So with that being said, is it plausible to get another amp to add power to my DB's as well as a subwoofer?- If so reccomendations for an amp and sub would be appreciated

 

[Mainah]

Finished tuning the amp this weekend - the best sound came from setting the LPF on the amp to the max setting (250Hz) and setting the head unit to 120Hz; I also set the sub gain on the amp down to the lowest setting and up to 20 on the head unit, and turned down the bass boost to the lowest setting on the amp. So basically letting the head unit manage all of the output settings to the sub. Also set the HPF on the full-range speakers to about midway on the dials for both front and rear channels, guesstimating that sets them to about 80Hz, since there's no graduated markings on the dials on the amp. I ended up setting the gain on the full-range front and rear channels to about halfway (12 o'clock position) - found that gave me sufficient volume without clipping/distortion.

I did try matching the LPF of on the head unit and amp as you suggested (setting both to 120Hz), but I was hearing some weirdness going on at higher volumes when I did that. Not sure if that was just my ears or not, but it sounded better to me the other way, so I set the amp to 250Hz and the head unit to 120Hz and left it.

Thanks for all of the help and detailed explanations on all of this, Mainah! My system sounds really good now, I'm looking forward to getting on the water to test it out live.

Great! That weirdness was most likely phase distortion and not just your ears. Plus 20 DB on the head unit out to the amp with the amp gain all the way down may not be good for the amp long term as that may be too much input voltage at high volume. Hard to say without knowing the actual components used inside the amp and testing the output of the headunit. I would try tuning to plus 10 on the headunit and whatever is needed for the amp gain with that just to be on the safe side. Other than that sound like you are getting the most out of it you can safely and I bet you will be darn happy with that until you get the bug to do more. The only cure for that bug is more time and money. Makes me sick to think about how much I have spent to date on audio alone.