Modding noisy monitors

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Magnetic Services
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Modding noisy monitors

Post by Magnetic Services » Fri Aug 20, 2021 11:36 am

I recently got some JBL LSR306P MkII monitors for a really good price. They sound fantastic and just as good or better than my old M-Audio 8-inch monitors they replaced. Overall amazing speakers for the price.

The only drawback is that they're pretty noisy. There's a constant hiss no matter what the output is set at, no change when using different inputs, HF trim, etc (seems to be just part of the circuit design). It's not so bad if you just have a stereo pair and you're a couple feet away, but I've got a full 5.1 setup and want to expand even more (hence the need for cheap monitors).

So, my question: how easy or hard would it be to make these quieter? Did they just use cheap capacitors or some other component that's easy to replace? Or am I stuck with noisy monitors? I have some soldering and electronics repair experience, but I'm no Jim Williams.

Thanks TapeOppers :)

Edit:

Product page: https://jblpro.com/en/products/306p-mkii
Manual: https://jblpro.com/en/site_elements/3-s ... al-english

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vvv
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Re: Modding noisy monitors

Post by vvv » Fri Aug 20, 2021 12:50 pm

I have no experience with these, but if you checked reviews and forums and such and no one else mentions the issue, I'd contact JBL.
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winky dinglehoffer
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Re: Modding noisy monitors

Post by winky dinglehoffer » Fri Aug 20, 2021 1:55 pm

One thing I have heard (and which experience tends to bear out) is that less expensive Class D amps tend to have hiss. Whether the level of hiss you're hearing is typical for the JBLs (or whether it's louder than the hiss in comparable monitors), I don't know.

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Re: Modding noisy monitors

Post by The Scum » Fri Aug 20, 2021 5:20 pm

That's what the bath tissue over the tweeters is for.
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Scodiddly
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Re: Modding noisy monitors

Post by Scodiddly » Fri Aug 20, 2021 7:57 pm

I've got a pair of the LSR305's, and they're pretty quiet.

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digitaldrummer
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Re: Modding noisy monitors

Post by digitaldrummer » Sat Aug 21, 2021 6:37 am

do they hiss when there is nothing connected (beside the power cable obviously)? in other words, nothing connected to the inputs. If not, then I'd say the issue is either cables (are they balanced/XLR?) or something coming from the interface. If it is still hissing, then as said earlier, I'd recommend contacting JBL as it sounds like something is defective. of course if there is no warranty and they come back with a ridiculous repair cost, then you could try some new caps...

btw, I have some class D monitors too (Fluid FX80) and absolutely no hiss.
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winky dinglehoffer
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Re: Modding noisy monitors

Post by winky dinglehoffer » Sat Aug 21, 2021 8:32 pm

digitaldrummer wrote:
Sat Aug 21, 2021 6:37 am
.

btw, I have some class D monitors too (Fluid FX80) and absolutely no hiss.
My FX80s have a faint hiss--not nearly loud enough to be an issue, but it's there. I looked around the internet a bit & found a lot of reports of Class D amps with hiss, but in some cases one owner of a particular model amp would report hiss while another owner of the same model would report that his amp was dead silent.

What I haven't found is any info on what the cause of the hiss is, and whether there's a reliable way to correct it.

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Nick Sevilla
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Re: Modding noisy monitors

Post by Nick Sevilla » Sun Aug 22, 2021 6:34 pm

Scodiddly wrote:
Fri Aug 20, 2021 7:57 pm
I've got a pair of the LSR305's, and they're pretty quiet.
I second this. They sound great too.

Maybe your are hooked up wrong? Unbalalnced vs balanced in the back? Noisy source?

If it is only one, I might suspect a bad speaker amp, but if it both... I'd suspect user error before something technical.
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Magnetic Services
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Re: Modding noisy monitors

Post by Magnetic Services » Tue Aug 24, 2021 10:33 am

Thanks for the replies everyone. I'm fairly certain it's the class D amps - the noise starts when the speakers are turned on and doesn't change no matter what they're connected to, gain level doesn't change anything, etc. From searching online it sounds like a known issue, and since I have 5 of these, I know it's not just a random problem with one of them. I guess the previous generation MKIs were quieter for some reason, maybe they cut some corners with the MKIIs.

I know all active speakers have some noise--my old ones definitely did if you put your ear right up to them--but this is just a bit too much of a noise floor when you have 5 speakers on. I guess you get what you pay for, and I got these for like 60% off, so I can't really say I'm disappointed, haha. I was just hoping someone knew of one component that causes hiss that might be easy to replace.

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