Really harsh/bright/piercing audio

[Romans5.8 10+ year member]

Hello friends!

I installed a pair of Polk MM651 Marine speakers into my motorcycle fairing, along with a Rockford Fosgate PBR300X2 amplifier. The audio quality is really harsh at high frequencies. FM audio is really awful, sounding distorted and harsh at all volumes. Audio from my iPhone sounds much better, but it's still really harsh (it makes me cringe) with high pitched and especially loud segments of music (think, guitar solo). Mid and low ranges sound fine. I don't listen to a lot of FM radio, but I honestly cannot now; it's just too harsh.

Being mounted in a fairing and in a motorcycle, I am not expecting stellar audio quality. But this is super harsh. One possibility is just that the OEM radio *****. I'm using high level inputs to the amplifier. I simply diverted the factory speaker connections into the amplifier, and connected the new speakers tor the amplifier using the wires supplied by the aftermarket speakers. Doing it this way prevented cutting into the factory audio harness (just cutting the speaker leads, which has a LOT more room to work with than the main harness and can be more easily returned to stock). It has limited adjust (treble, mid, bass) and they don't seem to make significant changes. Simply turning down the treble for example doesn't change the harshness, it just makes it sound muddy and piercing, instead of bright and piercing (if that makes sense?)

If it's not that; what else could it be? I'm trying to preserve the OEM look as much as possible, so I'd like to avoid an aftermarket head unit. Plus, it's hard to find a marine head unit (or any head unit, really) that doesn't look obnoxious/stupid. (Side rant: dear audio people; maybe make one thing that doesn't look like a transformer and have flashing lights all over it?) Any potential course of action here?

I set the amp using "ohms law". I went pretty conservative, not wanting to drive the speakers too hard; since it would be easy (at 70mph) to drive them super hard for long periods of time. So I played a 1khz test tone at full volume (speakers not connected, ha!) and used my multi-meter to set the amp to just a bit under 100 watts at 2.7 ohms. The speakers are rated for 100 watts at 2.7ohms. That's at a volume level of "30", I generally listen between 15 (55mph) - 20 (70-75mph). This piercing harshness is at anything above about 8 or 10 though; and it still sounds bright at soft volumes; it's just not loud enough to really hear I suppose. I don't know where there is distortion in the factory head unit; but I didn't notice much at max volume before with stock speakers. I routinely ran that thing for hours at maximum volume (which was about as loud as 13-15ish is now with the new amp and speakers). For the record, that's putting the amplifier at about "4" out of "11" (it goes to 11!) on the gain knob. I DID try to set the amplifier at a volume of 15 to be maxed out (thinking I could avoid distortion and that may have been the problem, and of course, just never go past 15). But it wasn't any different, it was just as harsh; and there were huge jumps between each press of the volume switch on the handlebar. I elected this route because I can dial in the volume to what I want, and it doesn't seem any better or worse when the amp is set at max volume vs. when it's set at half volume (of the head unit).

Any thoughts? Suggestions?

Thanks!

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[Jeffdachef 5,000+ posts]

Hello friends!
I installed a pair of Polk MM651 Marine speakers into my motorcycle fairing, along with a Rockford Fosgate PBR300X2 amplifier. The audio quality is really harsh at high frequencies. FM audio is really awful, sounding distorted and harsh at all volumes. Audio from my iPhone sounds much better, but it's still really harsh (it makes me cringe) with high pitched and especially loud segments of music (think, guitar solo). Mid and low ranges sound fine. I don't listen to a lot of FM radio, but I honestly cannot now; it's just too harsh.

Being mounted in a fairing and in a motorcycle, I am not expecting stellar audio quality. But this is super harsh. One possibility is just that the OEM radio *****. I'm using high level inputs to the amplifier. I simply diverted the factory speaker connections into the amplifier, and connected the new speakers tor the amplifier using the wires supplied by the aftermarket speakers. Doing it this way prevented cutting into the factory audio harness (just cutting the speaker leads, which has a LOT more room to work with than the main harness and can be more easily returned to stock). It has limited adjust (treble, mid, bass) and they don't seem to make significant changes. Simply turning down the treble for example doesn't change the harshness, it just makes it sound muddy and piercing, instead of bright and piercing (if that makes sense?)

If it's not that; what else could it be? I'm trying to preserve the OEM look as much as possible, so I'd like to avoid an aftermarket head unit. Plus, it's hard to find a marine head unit (or any head unit, really) that doesn't look obnoxious/stupid. (Side rant: dear audio people; maybe make one thing that doesn't look like a transformer and have flashing lights all over it?) Any potential course of action here?

I set the amp using "ohms law". I went pretty conservative, not wanting to drive the speakers too hard; since it would be easy (at 70mph) to drive them super hard for long periods of time. So I played a 1khz test tone at full volume (speakers not connected, ha!) and used my multi-meter to set the amp to just a bit under 100 watts at 2.7 ohms. The speakers are rated for 100 watts at 2.7ohms. That's at a volume level of "30", I generally listen between 15 (55mph) - 20 (70-75mph). This piercing harshness is at anything above about 8 or 10 though; and it still sounds bright at soft volumes; it's just not loud enough to really hear I suppose. I don't know where there is distortion in the factory head unit; but I didn't notice much at max volume before with stock speakers. I routinely ran that thing for hours at maximum volume (which was about as loud as 13-15ish is now with the new amp and speakers). For the record, that's putting the amplifier at about "4" out of "11" (it goes to 11!) on the gain knob. I DID try to set the amplifier at a volume of 15 to be maxed out (thinking I could avoid distortion and that may have been the problem, and of course, just never go past 15). But it wasn't any different, it was just as harsh; and there were huge jumps between each press of the volume switch on the handlebar. I elected this route because I can dial in the volume to what I want, and it doesn't seem any better or worse when the amp is set at max volume vs. when it's set at half volume (of the head unit).

Any thoughts? Suggestions?

Thanks!

There's no way around it. You need a head unit with a 13 band EQ or more. Or if you can hide a small digital sound processor somewhere. You just need some heavy EQ along with a head unit with better Digital audio convertors. Your stock head unit is 8 to 12 bit at best. you need 24 bit. With the EQ you'll be lowering 5khz to 8khz range a lot to tame the harshness. However I noticed with a good head unit, it already takes away the harshness you get with a crappier radio. The radio does that much. Nothing you do amplifier settings or playing your speakers for a long time will solve your issue. All those are completely useless to the problems you are facing.

If you do get a head unit make sure its 13 band EQ or higher, 24 bit dac. decent pre-out voltage. Hard to keep the stock look if you want quality audio.

 

[hispls 5,000+ posts]

I assume they're on-axis (pointed right at you)?

Try positioning yourself 40 degrees off to the side of the speakers and see if that's any better. Many of these type of speakers are intended to mount in oddball places and will sound rough when they're actually pointed right at you.

If they sound bad off-axis as well I'd suspect the source unit as well, in which case I'm not too savvy on what's out there for weather resistant equipment.

 

[Romans5.8 10+ year member]

There's no way around it. You need a head unit with a 13 band EQ or more. Or if you can hide a small digital sound processor somewhere. You just need some heavy EQ along with a head unit with better Digital audio convertors. Your stock head unit is 8 to 12 bit at best. you need 24 bit. With the EQ you'll be lowering 5khz to 8khz range a lot to tame the harshness. However I noticed with a good head unit, it already takes away the harshness you get with a crappier radio. The radio does that much. Nothing you do amplifier settings or playing your speakers for a long time will solve your issue. All those are completely useless to the problems you are facing.

Thanks. That's what I feared, I thought I'd ask here juuust in case there was something that could be done.

I don't think there's ANY digital to analog converter at all. The audio it receives from my iPhone, for example, is using the 30-pin dock connector and it's analog leads (the Apple 30-pin dock connector outputs analog audio; if you didn't know. The device itself, or in this case, an adapter, contains the DAC). It receives digital information for on-screen data; but even a brand new 2017 model of this bike will still only support a 30 pin dock connector (with requisite adapter and included DAC) and it's analog audio signal. Of course, FM radio has no DAC, since it's analog entirely, right?

I can probably fit a DSP. There's actually a lot of room inside that fairing, AND convenient mounting brackets and power leads! There are two available audio options, a SiriusXM module and a CB radio module; neither of which I have any interest in. Presently, the Amp is mounted where those would go, and there's still room. But, would that really make a difference? I'll confess ignorance when it comes to a lot of this stuff; at least compared to most of you here. I mean, if the source is awful, is a DSP really going to be able to polish the turd?

 

[Romans5.8 10+ year member]

I assume they're on-axis (pointed right at you)?
Try positioning yourself 40 degrees off to the side of the speakers and see if that's any better. Many of these type of speakers are intended to mount in oddball places and will sound rough when they're actually pointed right at you.

If they sound bad off-axis as well I'd suspect the source unit as well, in which case I'm not too savvy on what's out there for weather resistant equipment.

I'll check that out! If they sound good off-axis, what do I do? It's not like I can move them. (And yes, they are pointed right at me).

I don't know much about marine grade stuff either. There seems to be limited availability and they just look awful. Vanity, yes! But they're intended for boats (of course) and it would seem the market wants flashy, usually white, with bright colorful lights and displays. The stock radio is a very plain brushed-steel look (picture below if you're curious). I was thankful to find some decent looking marine grade speakers.

It absolutely can be done. An adapter is available, as is wiring to preserve the handlebar controls. I just don't want to if I absolutely don't have to. It sounded fine stock, just quiet.

 

[Papermaker85 5,000+ posts]

off axis is going to just kill highend. above 12k.

chances are the peak is around 2-5k..

 

[los33]

Have you considered filtering using caps on the speakers?

Wont help much for quality but will kill a bit of the harshness.

Sent from my Moto G4 using Tapatalk

 

[Jeffdachef 5,000+ posts]

Thanks. That's what I feared, I thought I'd ask here juuust in case there was something that could be done.
I don't think there's ANY digital to analog converter at all. The audio it receives from my iPhone, for example, is using the 30-pin dock connector and it's analog leads (the Apple 30-pin dock connector outputs analog audio; if you didn't know. The device itself, or in this case, an adapter, contains the DAC). It receives digital information for on-screen data; but even a brand new 2017 model of this bike will still only support a 30 pin dock connector (with requisite adapter and included DAC) and it's analog audio signal. Of course, FM radio has no DAC, since it's analog entirely, right?

I can probably fit a DSP. There's actually a lot of room inside that fairing, AND convenient mounting brackets and power leads! There are two available audio options, a SiriusXM module and a CB radio module; neither of which I have any interest in. Presently, the Amp is mounted where those would go, and there's still room. But, would that really make a difference? I'll confess ignorance when it comes to a lot of this stuff; at least compared to most of you here. I mean, if the source is awful, is a DSP really going to be able to polish the turd?

I'll check that out! If they sound good off-axis, what do I do? It's not like I can move them. (And yes, they are pointed right at me).
I don't know much about marine grade stuff either. There seems to be limited availability and they just look awful. Vanity, yes! But they're intended for boats (of course) and it would seem the market wants flashy, usually white, with bright colorful lights and displays. The stock radio is a very plain brushed-steel look (picture below if you're curious). I was thankful to find some decent looking marine grade speakers.

It absolutely can be done. An adapter is available, as is wiring to preserve the handlebar controls. I just don't want to if I absolutely don't have to. It sounded fine stock, just quiet.

]

throw your stock speakers back on and put them on the amp. They'll surprise you.

Every radio has a DAC or else it wont be able to play anything. The stock stereo also has its own built in EQ curve which boost things up to try to make up for the low quality stock speakers they used. So in a sense the stock stereo will only work well with stock speakers. When you use aftermarkets, they are subjected to the same EQ cuve which boosts frequencies that should not be boosted which leads you to your issue of harsh highs.

Yes a DSP will make every difference possible. You wont get anywhere without EQ tuning even in a good setup with a good head unit and great speakers, you'll still need massive amounts of EQ tuning due to the listening environment. Those polk MM marine speakers shouldn't sound harsh at all, my old manager's boat used them and he barely needed to lower the 6.3khz range a bit on his kenwood head unit.

Soo how crappy the sound would look like without EQ? with EQ should be more straight and linear which leads to very pleasant, full, smooth and detailed sounding music.

 

[Jeffdachef 5,000+ posts]

Have you considered filtering using caps on the speakers?
Wont help much for quality but will kill a bit of the harshness.

Sent from my Moto G4 using Tapatalk

that will do more harm then good. Basically turn it into mud cutting off everything above aka the sparkling smooth sounding upper frequencies(10khz+) that actually add detail.

 

[Romans5.8 10+ year member]

throw your stock speakers back on and put them on the amp. They'll surprise you.
Every radio has a DAC or else it wont be able to play anything. The stock stereo also has its own built in EQ curve which boost things up to try to make up for the low quality stock speakers they used. So in a sense the stock stereo will only work well with stock speakers. When you use aftermarkets, they are subjected to the same EQ cuve which boosts frequencies that should not be boosted which leads you to your issue of harsh highs.

Yes a DSP will make every difference possible. You wont get anywhere without EQ tuning even in a good setup with a good head unit and great speakers, you'll still need massive amounts of EQ tuning due to the listening environment. Those polk MM marine speakers shouldn't sound harsh at all, my old manager's boat used them and he barely needed to lower the 6.3khz range a bit on his kenwood head unit.

Soo how crappy the sound would look like without EQ? with EQ should be more straight and linear which leads to very pleasant, full, smooth and detailed sounding music.

But there's no digital signal so what does the DAC do? Just trying to learn here. The OEM stereo supports AM, FM, and analog audio inputs from the 30 pin connector. With no digital signal, what does the DAC do?

 

[Jeffdachef 5,000+ posts]

But there's no digital signal so what does the DAC do? Just trying to learn here. The OEM stereo supports AM, FM, and analog audio inputs from the 30 pin connector. With no digital signal, what does the DAC do?

All the signal you mentioned is in digital form its converted into an analogue signal. Every radio has it built in. There is no radio built without a dac. Music itself is in digital form and needs to be converted to analogue for anything to be played its not automatically analog especially am and FM. Thats not the most important part though. Read the part about the stock head unit with the stock EQ curve built in. Thats more relevant than anything here.

 

[hispls 5,000+ posts]

I'll check that out! If they sound good off-axis, what do I do? It's not like I can move them. (And yes, they are pointed right at me).
I don't know much about marine grade stuff either. There seems to be limited availability and they just look awful. Vanity, yes! But they're intended for boats (of course) and it would seem the market wants flashy, usually white, with bright colorful lights and displays. The stock radio is a very plain brushed-steel look (picture below if you're curious). I was thankful to find some decent looking marine grade speakers.

It absolutely can be done. An adapter is available, as is wiring to preserve the handlebar controls. I just don't want to if I absolutely don't have to. It sounded fine stock, just quiet.

Options would be pick some speakers which sound better on-axis or move/angle the ones you have.

Another good theory is some sort of built in EQ in the factory head unit that overcomes some weak spots in the stock speakers. Flashy and chrome sells I'm afraid.
[/QUOTE]

 

[Romans5.8 10+ year member]

All the signal you mentioned is in digital form its converted into an analogue signal. Every radio has it built in. There is no radio built without a dac. Music itself is in digital form and needs to be converted to analogue for anything to be played its not automatically analog especially am and FM. Thats not the most important part though. Read the part about the stock head unit with the stock EQ curve built in. Thats more relevant than anything here.

The conversion happens at the source of transmission. FM and AM are analogue signals. So is an RCA line level audio signal (which is what comes out of the 30 pin connector; hence the DAC in the adapter. It's essentially a mini RCA connection, which is analogue as well). It may have a DAC, but no, none of those signals are digital. They just aren't. I'm not an audio geek per se but I am an electronics geek. In my livingroom is a gorgeous old AM/FM radio (that supports quadriphonic FM! Which is now defunct) that most certainly contains no DAC, I've restored it myself. It's an entirely analog radio. It supports Vinyl, AM, FM/FM Stereo/FM Quadrophonic; all of which are analog. CD, mp3, aac (and other lossless formats), HD Radio, XM/Sirius are all digital. AM/FM, RCA (line level), vinyl, most tape formats (except a select few digital tape formats; but compact cassettes and 8 tracks are both analog), etc are all analog. The audio is stored in an analog format, not in bits which need to be converter to waveforms. The FM transmitter is transmitting waveforms directly to the radio. If it was transmitting bits, (which would need converting), then it would go in and out like sattelite radio; not get 'fuzzy'. Again, not to say it doesn't have a DAC in it somewhere (I'm not sure what for, though). But the signals it's receiving are definitely analog signals. My assumption that it has no DAC comes from the fact that it CAN'T accept any sort of digital connection, like being able to connect with an iPod digitally, but instead relies on the iPod (or iPhones) built in DAC and receives an analog signal from that. You might be thinking of a DSP (Digital Signal Processor). That it might, in fact, have. Something that digitally adjusts the incoming analog signals (including a signal FROM a DAC, it would be connected to it's analog output pins). It very well may use some sort of internal DSP, but as you say, it's limited by a built in EQ curve and not adjustable.

Yeah, the stock EQ curve makes a lot of sense. I may have to break down and finally put in an aftermarket radio. I just really don't want to! But, it may be what has to happen!

I like the idea of an external signal processor. If that would work. And that would be something that would connect to the high level outputs I assume?

EDIT: Did some googling, and it looks like Rockford Fosgate makes one that I MIGHT be able to fit inside the fairing, that would be plug and play with my current amp.

EDIT2: No, that probably won't work; all it advertises is being able to "boost" treble and bass. That's not my issue right? I need something that can go frequency by frequency and drawn down the ones that are too hot, right?

Here's a shot of the amp installed, to give you an idea of how much room I have to work with.

Ignore the sloppy wiring, I was just zip-tying stuff out of the way while working on other things. Notably, the power wires and not running WITH the speaker wires. Power runs directly down the center, speaker wires run on each side.

 

[Boomin_tahoe 5,000+ posts]

^^That doesn't look all that bad, really. I've seen MUCH worse wiring everywhere. I'd rather see zip ties than wiring spread out in a vehicle. In your case, a motorcycle. It looks neat and tidy to me tho. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

I'm commenting because I have 2 of these Polk sets myself. I have read on other forums that people have stated the tweeters are kinda harsh/bright in some areas of music. That's when tuning comes into play. Your factory HU may be the cause of the Polks not sounding good because of no eq/x-over built in to fine tune the sound, and what sounds best to your ears.

 

[Jeffdachef 5,000+ posts]

I like the idea of an external signal processor. If that would work. And that would be something that would connect to the high level outputs I assume?

EDIT: Did some googling, and it looks like Rockford Fosgate makes one that I MIGHT be able to fit inside the fairing, that would be plug and play with my current amp.

EDIT2: No, that probably won't work; all it advertises is being able to "boost" treble and bass. That's not my issue right? I need something that can go frequency by frequency and drawn down the ones that are too hot, right?

the thing about external DSP is, its expensive around 600 dollars in general. If it only boosts bass and treble its the wrong one.

The actual one is tuned by plugging into a laptop and working the software. aka here's an example of the 360.3

For a cheaper option you might want to look at "minidsp"