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Monitor Tonality Differences

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Monitor Tonality Differences

Postby electricblue » Sat Mar 28, 2020 2:52 am

The situation... I have a pair of Mackie HR624mk2 (not matched and don't think they're sold as a matched pair) as my main reference monitors. I thought I had a blown tweeter, as one sounds brighter than the other, which also includes some light distorted clipping on certain instruments, like electric guitar and piano. I can verify this by panning hard L/R and comparing. The high frequency filter is set to neutral on both. Took it to get repaired and it turns out the tweeter is fine. This series of monitor is very neutral in it's sound, so I'm wondering if this could be a manufacturing flaw in the one monitor? Has anyone experienced this to some degree with other brands? As imagined, it's an annoying audio OCD quirk when trying to get an accurate reading on how an instrument/ mix sounds.
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Re: Monitor Tonality Differences

Postby DC-Choppah » Sat Mar 28, 2020 4:32 am

Try switching the wires that feed the monitors. Move the L wire to R speaker and the R wire to L speaker.

See if the glitch follows the wires. If so, then it is coming from your sound source and not the monitors.
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Re: Monitor Tonality Differences

Postby Wonks » Sat Mar 28, 2020 8:06 am

However, if your room is not acoustically treated, it is more likely at least partially caused by frequency dips and humps caused by interactions between reflections and direct sound.

If you can run a dual-mono sine wave sweep, you'll probably find that the centre position moves around a lot instead of staying firmly between the monitors.

One other thing to try is physically swapping the monitors over. If the same position now exhibits the same frequency traits as before, then it's definitely not a monitor sound mismatch.
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Re: Monitor Tonality Differences

Postby Hugh Robjohns » Sat Mar 28, 2020 11:14 am

electricblue wrote:...one sounds brighter than the other...

It's quite possible that the two speakers do have different responses. Every speaker manufacturer aims to get the frequency response of their speakers within a set tolerance window. The less expensive the speaker, the wider that rolerance window tends to be (and vice versa, of course). So with speakers sold individually, it's entirely possible that one might be at the low side of the tolerance window and the other at the high side, and thus the sonic difference between them relatively large, even though both speakers are 'within tolerance' as far as the manufacturer is concerned.

However, the other issue is the one Wonks mentions, which is that the acoustic conditions in your listening room and local reflections can make a huge difference to the perceived sound quality of each speaker.

What I would suggest you do is take both speakers to a large room -- or even outdoors if you can -- and place them, one placed above the other on a tall stand of some kind well away from the floor and anything else that would cause local reflections. Feed the same things to each speaker in turn and listen to see if they sound the same or obviously different.

If they sound pretty much the same then you have a room or local reflections issue in your listening space. In that case, do whatever you can to improve your listening area. Treat the mirror points with broadband absorbers. Move anything acoustically reflective away from the speakers -- especially computer screens. Ideally, there should be nothing between the speakers, but that's usually impractcial, so the compromise is that there should be nothing forward of the line joining the two speaker baffles (and further back is better).

If they obviously don't sound the same you either have a manufacturing tolerance issue or a faulty speaker. If it's a tolerance thing you may be able to get them closer by tweaking the EQ controls on one speaker, although they are often too crude to help very much.

An alternative solution would be to use a room/speaker alignment system like Sonarworks whcih will measure and calculate the appropriate correction curve to bring both speakers into the correct alignment, regardless of their starting position!

... includes some light distorted clipping on certain instruments, like electric guitar and piano.

Assuming you are sending sensible input signal levels, and listening at sensible volumes, this is more suggestive of a fault somewhere, either in one of the drivers, or in the amplifier electronics. Having one speaker slightly brighter or darker than another, say, could be put down to tolerance issues... but one having a significantly different level of distortion artefacts is rather more concerning.

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Re: Monitor Tonality Differences

Postby ef37a » Sat Mar 28, 2020 12:13 pm

I agree about the distortion, should not be evident at any sensible level. Another good reason to buy a 'C' SPL meter and calibrate!

In addition to speaker tolerances there are also tolerances in the Cs&Rs in the crossover circuits. Again cost is a factor. You are not going to get 1%tol capacitors in inexpensive kit and even less likely better, hand picked caps.

There is always the possibility of circuit AND speaker tolerances adding up all in the wrong direction. Should of course never get past QC but, 'it'appen.

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Re: Monitor Tonality Differences

Postby James Perrett » Sat Mar 28, 2020 3:10 pm

electricblue wrote:which also includes some light distorted clipping on certain instruments, like electric guitar and piano.

I had this on one of my monitors recently. Full mixes with plenty of high frequency energy sounded fine but sparse mixes with less high frequency energy had some strange distortion going on. I ended up playing a sinewave sweep through the monitors to track the problem down.

It turned out to be corrosion in the tweeter which was causing the coil to rub against the magnet. Fortunately the monitors I use have replaceable tweeter diaphragms but in this case I was able to cure the problem myself by smoothing off the lumps caused by the corrosion.
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Re: Monitor Tonality Differences

Postby electricblue » Mon Mar 30, 2020 12:31 am

Thank you for all the responses and input! It's definitely either a swing in the tolerance that Hugh mentioned or a larger problem with the driver. I've swapped cables/ inputs, etc, but no difference. The clipping/ distorted sound is audible at sensible levels, as well as quiet. When soloing an instrument, it is more noticeable. For the time being I can work around the issue, but will likely replace the entire monitor soon.
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Re: Monitor Tonality Differences

Postby ef37a » Mon Mar 30, 2020 7:19 am

"replacing entire monitor"? Single?

I would have thought this a good opportunity to save for a pair of monitors of a rather higher grade?
The sole worker left could then be pressed into service as a centre mono 'check' speaker or foldback/talkback if the setup allows it.

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