Polk LSiM703 - harsh treble vs LSi9 or in general? How to fix?

CottageChz · January 2019

Hey guys,

New to the forum here, owned Polk speakers since around 2010, and have a question about my current setup. Thought some people here may have a similar experience, or input/recommendations for me.

I currently own Polk LSiM703s. Before this I had the LSi9s. Really loved the LSi9s, but read so many great things about the LSiM703s, so I took the plunge when I found a good deal.

The most notable improvement I hear is the bass. However, I've been wondering about the treble on these speakers. Don't get me wrong, the speakers sound pretty great, but sometimes I think the treble can be kind of harsh... almost scratchy at times, almost like a tiny bit of distortion. I really don't know, but I didn't notice this with the LSi9s.

I'm wondering if anyone else feels the same way, especially anyone who has listened/owned both LSi9 and LSiM703, or currently owns LSiM703s.

Below is the setup I use. It was the same setup for the LSi9s. Maybe someone can spot a weak link here. I really enjoy home audio and have a decent understanding of it, I think, but I am by no means a pro, so maybe there's something I'm missing.

-Usually playing music (typically 320 kbps mp3 or variable bit rate v0 mp3) from iTunes on my Mac Mini via digital optical
-Onkyo TX-8050 for preamp
-Fosgate Audionics 4125 for amp, speakers bi-amped (specs below)
-Polk LSiM703, bi-amped

Fosgate Audionics amp specs:
4 x 75w @ 8 ohms, <0.15% THD/IMD
4 x 110w @ 4 ohms, <0.25% THD/IMD
2 x 225w @ 8 ohms, <0.25% THD/IMD

In the end, I know that a lot of preferences when it comes to sound are subjective, and other things such as arrangement of the speakers and room can make a difference. Just wondering if anyone's had a similar experience with the LSiM703s, or anyone has recommendations for improvements based on the info I provided.

Thanks in advance!

CottageChz · January 2019

Also, I've owned the speakers since the spring, so they are surely broken in. Noticed the treble right away but wanted to give them some time... the treble thing still nags at me, so here I am.

dhart86 · January 2019

Welcome to Club Polk---I had the same experience. Love the smoothness of the Lsi9's. I couldn't figure out how to reconcile the treble on my 703's. I ended up selling the 703's (hated to b/c they looked real cool, but I buy speakers for the sound) I later bought the 705's and they sound much better. They are balanced from top to bottom. Don't know why but they just sounded right to me. Not the same treble issue as the 703's

WLDock · January 2019

I've had the 703's and a friend had the LSi9's years earlier. The LSi are more laid back and easy to listen to speaker.

LSi9 Measurements
703polk.fig1.jpg

Fig.1: Polk LSi9, pseudo-anechoic horizontal response at 45° (red) and 60° (blue) relative to tweeter axis.

The goals Polk had for the LSiM ring radiator tweeter over the LSi was to improve the top end response, dispersion, and eliminated horn loading. The LSiM line is more revealing and the 703's have a 5dB rise on the top end. The sound and interaction with the room may create a totally different experience...good or bad.

LSiM703 Measurements

Myself, I never found the tweeters harsh or distorted sounding. However, in some rooms maybe room treatments might be needed? or possibly a little 2-3dB padding on the tweeters like the switch that some vintage speakers have. Or maybe even a little EQ on the top end. Your TX-8050 receiver has treble control centered at 20KHz. Have you tried to reduce the level some?

WLDock · January 2019

Also, find the tracks that distort on the top end and see if both speakers are doing it. Switch the speakers around and see if its consistent with both or one speaker. Play one speaker at a time, etc. to rule of a hardware tweeter, crossover issue.

If no hardware issues then try to treat some of the early reflection points. Try to angle the speaker less on axis just to see if the sound changes for the better or worst, etc.

Emlyn · January 2019

It is not that the speaker is flawed. The LSiM line is more resolving than the older LSi line which sounded mildly rolled off to me. My guess is the 703s are showing some of the flaws in the source and components being used. The LSi9s would be a better choice in that type of compressed digital system.

I like both speakers and thought the LSi9 was by far the best in the old lineup. The LSiM 703 are also far better speakers overall, but when I use them with a receiver with a Class D amp they sound a bit thin. Put a good analog amp and tube preamp on them and they really shine. Almost like listening to a different speaker, but what is really going on is the speakers are properly showing what is upstream.

Clipdat · January 2019

Do you notice it when playing uncompressed .wav?

tonyb · January 2019

Emlyn wrote: »

It is not that the speaker is flawed. The LSiM line is more resolving than the older LSi line which sounded mildly rolled off to me. My guess is the 703s are showing some of the flaws in the source and components being used. The LSi9s would be a better choice in that type of compressed digital system.

I like both speakers and thought the LSi9 was by far the best in the old lineup. The LSiM 703 are also far better speakers overall, but when I use them with a receiver with a Class D amp they sound a bit thin. Put a good analog amp and tube preamp on them and they really shine. Almost like listening to a different speaker, but what is really going on is the speakers are properly showing what is upstream.

This ^^^

SIHAB · January 2019

I dunno. There is a bit of ring to the ring radiator IMHO.
Its less noticeable when not going head to head with
something else. Maybe that is what the OP is hearing.

F1nut · January 2019

Not that you will see this until I'm let out of polk prison, which I'm in for a completely unjustified reason.

It's not the speakers, it's everything else. Time to step up the source and gear.

StewartHolmes83 · January 2019

Getting rid of harsness, too bright and or forward sounding sound is not always the speakers issue, they may reveal it in your system yet can easily be dealt with in a number of ways. Changing resistors slightly before the tweeters in the crossovers, cable changes, acoustic improvements. It can go.

erniejade · January 2019

"Usually playing music (typically 320 kbps mp3 or variable bit rate v0 mp3) from iTunes on my Mac Mini via digital optical"

This goes right what has been said about the 703 being more resolving. The source might need to be stepped up.

Btw i am suprised you mention the 703 have more bass. When i had the 9's I thought they had quite a bit of bass. The bass to my ears is different on the 703 vs lsi9. Personal preference and room acoustics can also play a big part.

WLDock · January 2019

It would be great is you could listen to the tracks that distort with the speakers connected to another system. One way to see what different electronics sound like. See if one of the local high end audio stores will allow you to bring them in for a listen with their electronics.

rooftop59 · January 2019

WLDock wrote: »

See if one of the local high end audio stores will allow you to bring them in for a listen with their electronics.

What are these “high end audio stores” of which you speak???

WLDock · January 2019

I guess the audio business has dried up in several areas huh? I guess back when there were 5-6 within a 30 min drive from me only a few would probably let one bring in their own gear to demo. I guess today its tough to find any stores in some areas.

dromunds · January 2019

Emlyn wrote: »

It is not that the speaker is flawed. The LSiM line is more resolving than the older LSi line which sounded mildly rolled off to me. My guess is the 703s are showing some of the flaws in the source and components being used. The LSi9s would be a better choice in that type of compressed digital system.

I like both speakers and thought the LSi9 was by far the best in the old lineup. The LSiM 703 are also far better speakers overall, but when I use them with a receiver with a Class D amp they sound a bit thin. Put a good analog amp and tube preamp on them and they really shine. Almost like listening to a different speaker, but what is really going on is the speakers are properly showing what is upstream.

I also agree with this. I really like the 703’s. I would never call them harsh in my system. I am consistently pleased with their sound. My GF uses my 9’s currently, very good speakers but 703’s are far better overall as mentioned above.

sponger · January 2019

You lost some power output with the LSiM's ohm load. Maybe it's possible that the midrange is not getting enough juice for it to keep up with the tweeter?

That Fosgate has quite a beefy looking layout based on a quick search. Not only is it 2 ohm stable, but it's also bridgeable. You could be squeezing 225W/channel in that case. So, instead of bi-wiring, try bridging it. If anything, it will just sound a whole lot better for sure. Please ask for help with bridging if you're not confident with that.

Also, on the off chance that this is your set-up minus the LSi9 (what are the odds, right?), then I wonder if you are still into vinyl. The set-up matches your description except for the TT and the speakers of course. That includes the mac mini.

CottageChz · January 2019

sponger wrote: »

Also, on the off chance that this is your set-up minus the LSi9 (what are the odds, right?), then I wonder if you are still into vinyl. The set-up matches your description except for the TT and the speakers of course. That includes the mac mini.

@sponger you are quite the sleuth! That is my setup from several years ago, but as you can tell, it's still pretty similar!

@erniejade It's not that I thought the bass on the 9s was bad. It just seems like the LSi has more in general.

I did realize that I lost some power with the LSiM's ohm load, which was part of the reason why I posted the amp specs. Was wondering if that could be part of it.

I had also wondered about the quality of the source, as several have mentioned. Might need to dig out the CD player and play some CDs that I can compare to the MP3 rips on my Mac Mini.

Would love to try out some different equipment, tube amps, etc., but I don't want to throw a ton of money at this to "maybe" fix the problem.

And I never really though the speaker was flawed per se... figured it is more likely something in my system, the way I'm playing the music, etc.

I appreciate all of the feedback here. If anyone has other ideas or has had a similar issue I'd love to hear them. In the meantime I am going to play around with some of the suggestions here and see if I can notice any differences.

CottageChz · January 2019

@sponger Also, yes, still into vinyl, but I find myself listening to digital more these days for the sake of convenience and for the larger selection at hand.

rpf65 · January 2019

What speaker cables are you using?

marvda1 · January 2019

Fosgate Audionics 4125 for amp, speakers bi-amped (specs below)
-Polk LSiM703, bi-amped

Fosgate Audionics amp specs:
4 x 75w @ 8 ohms, <0.15% THD/IMD
4 x 110w @ 4 ohms, <0.25% THD/IMD
2 x 225w @ 8 ohms, <0.25% THD/IMD

forget about trying to bi-amp with a multi channel amp, you are not really a bi-amp setup unless the amp has individual power transformers for each channel. try running the speakers two channel with the 225 watts and see how it sounds.

also if you can borrow a two channel preamp give it a go.
where are you located? there might be someone close to you that will bring some pieces over to how the system sound changes.

i would also try bi-wiring from the 2 channel setting before trying the pseudo bi-amp setup.

CottageChz · January 2019

@rpf65 Nothing fancy for speaker cable. Any recommendations that aren't too expensive? That has always seemed like a crazy thing to spend a lot of money on, to me. But I could be wrong. Always trying to learn more.

@marvda1 I have thought about trying two channel to get more power to each speaker. I will give that a shot at some point this week when I try some of these other ideas. I am located in Pittsburgh.

rpf65 · January 2019

Cables, like everything else audio, is a personal preference/choice. In other words, the cables I like, on the same system in the same room, you may dislike, or hear no difference between the two.

Anyway, that said, I’m using Analysis Plus Oval 9 on my LSI M705, and Analysis Plus Cleat Oval for the LSI M706C. When I switched from the Canare that I was running, to the Oval 9, the overall improvement was astounding. Really changed the overall sound stage so much that the center channel was isolated and actually sounded worse than the RTI A4 that I used to run. I switched them.

Originally switched to the Oval 9 for music.

When I added the Clear Oval to the mix, the center blended in seamlessly. I’m happy with them, even if they cost a little more than I wanted to spend.

The Clear Ovals are pretty reasonably priced, in my opinion. May want to give them a try. The Cable Company’s lending library may be something you want to look into if you’re unsure about cables.

https://www.thecableco.com/clear-oval-speaker-cable-pair.html

sponger · January 2019

CottageChz wrote: »

@marvda1 I have thought about trying two channel to get more power to each speaker. I will give that a shot at some point this week when I try some of these other ideas. I am located in Pittsburgh.

The decision is ultimately yours. But I'm surprised that more power isn't at the top of your list. Underpowering a speaker is perhaps the easiest way to make it sound its worst, and 75wpc as most would agree is hardly adequate for any LSiM speaker. Also, it's 3X the power by bridging the amp channels. I see no reason why those speakers wouldn't sound radically different afterward. 75wpc vs. 225wpc? I'm just not sure why that would even be debatable.

sponger · January 2019

DSkip wrote: »

Power doesn’t solve issues.

That's like saying there's no such thing as underpowering. They're underpowered. This means they need more power. The "I didn't know my cables sucked until I went from the LSi to the LSiM" scenario is an unlikely outcome. Also, the Dueventi is a class A, and of course you're aware that it's apples and oranges when comparing to an A/B.

skrol · January 2019

CottageChz · January 2019

DSkip wrote: »

Power doesn’t solve issues. Quality does. He has enough power for them but he has bad gear and bad files in front of good speakers. I imagine cables aren’t doing any favors either. Sorry to the OP but once you move up the chain it gets easier and easier to hear lower quality gear and their effect on the sound.

As far as power, I’d take the Dueventi at 20 watts over my McIntosh MC2500 at 500 watts on most of my speakers.

No offense taken. I am here for honest opinions and ideas on how to possibly fix the issue I described. I know that I don’t have top end gear. So if that’s really what you think, then what would you suggest as the weakest link(s) in my system, and what would you suggest as a fix without breaking the bank? I don’t have friends who are into this stuff and as a result I try to learn what I can online, and try to get advice from people who are into home audio. So that’s what I’m doing here. I really do appreciate all the input.

Clipdat · January 2019

Aren't these distortion specs a little high and undesirable?

4 x 75w @ 8 ohms, <0.15% THD/IMD
4 x 110w @ 4 ohms, <0.25% THD/IMD
2 x 225w @ 8 ohms, <0.25% THD/IMD

marvda1 · January 2019

i did not suggest going to the 225 watt option because of the power but to get away from the type of bi-amping being used. someone asked you about the treble control on the onkyo, did you try using it?

what is your room like, carpet,tile,wood flooring? is there a lot of windows in the room?

what type of stands are you using for the speakers?

what would be your budget if you decided to get a pre amp? amp only? amp + pre amp?

heiney9 · January 2019

Get rid of the horrid MP3's and using Apple streaming. The source is most likely the issue. These speakers are more revealing than the LSi9's.

H9

DaveHo · January 2019

Are you sure you don't have a bad tweeter? The QC on my first set of 705's was terrible. One of the issues was a scratchy tweeter, most noticeable with piano. This sounds like what you are describing.

Polk LSiM703 - harsh treble vs LSi9 or in general? How to fix?

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