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nasty low resonace

Postby damartin » Thu Oct 29, 2020 1:13 pm

Hi guys,

I encounter an odd issue: nasty low resonances ONLY when I am fretting C note on my electric guitar both on low E string (8th fret) and A string (3rd fret). This happens when volume is fairly high and the low register is a little bit accentuated (within normal limits, though - just tweaking the amp sim searching for different tones) when I am tweaking my amp sim. so, it seems it's a specific frequence that resonates. In the case of other notes on the fretboard nothing special apart form the usual adjustments to the low register. When I turn down the bass (on my monitors or amp sim) under a value the issue dissapears. FYI - my DI setting is straightforward: electric guitar>audio interface>computer (amp sims) >studio monitors. I am not sure that the issue appears when I am using headphones appart from the usual low resonance when the low register is accentuated and the volume is turned up. what do you think? is the guitar? the monitors, some object that resonates in my room?
Cheeers! Martin
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Re: nasty low resonace

Postby Sam Spoons » Thu Oct 29, 2020 2:29 pm

That's C one octave below middle C with a frequency of 126Hz. That's a very likely room resonance so have you tried moving to another position in the room, maybe the dead centre where your room resonances should be cancelling out? Or it could be a resonance in the guitar itself but I think that's less likely.
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Re: nasty low resonace

Postby damartin » Fri Oct 30, 2020 2:01 pm

thanks for replying. yes, I am thinking too that my room could be the problem. anyway, I just bought my studio monitors and I wanted to ask around to rule out a possible malfunction.
All best, M
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Re: nasty low resonace

Postby Sam Spoons » Fri Oct 30, 2020 2:33 pm

Do you have acoustic treatment in the room (you would need bass traps in addition to the 'normal' 50-100mm 'broad band absorbers' to effectively reduce 126Hz)? How big is your room?
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Re: nasty low resonace

Postby CS70 » Sat Oct 31, 2020 10:35 am

Yeah it's happened to me as well and it usually is either a result of how the particular space interacts with the amp (a kind of frequency-specific feedback if you want), or of something that's rattling in the amp (or outside!) when excited with enough energy by a small frequency band. Especially low strings do that, as they carry more energy and move more air.

I remember once getting a bit crazy because of a bad sound someplace on the low E, only to find out it was a piece of metal on a shelf that was vibrating only when I played that note! It merged so well with the sound (and it was so unexpected) that I was very surprised when I found out!

It could, of course, also be other things - a tube or a pickup that's microphonic or is rattling at a certain band.. bring the amp somewhere else and give it a try there. If the problem disappears, it's the room or something in it!
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Re: nasty low resonace

Postby Martin Walker » Sun Nov 01, 2020 4:14 pm

CS70 wrote:Yeah it's happened to me as well and it usually is either a result of how the particular space interacts with the amp (a kind of frequency-specific feedback if you want), or of something that's rattling in the amp (or outside!) when excited with enough energy by a small frequency band. Especially low strings do that, as they carry more energy and move more air.

I remember once getting a bit crazy because of a bad sound someplace on the low E, only to find out it was a piece of metal on a shelf that was vibrating only when I played that note! It merged so well with the sound (and it was so unexpected) that I was very surprised when I found out!

I've occasionally had problems over the years with radiators rattling in sympathy with particular notes, but you can normally track such things down by repeatedly playing the offending note while walking around the room and feeling for vibration, even if you can't see anything moving ;)


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Re: nasty low resonace

Postby ChrisF-AdamsHill » Mon Nov 02, 2020 4:06 am

I have been working on getting closer to a flat frequency curve for audio playback in my home studio. Built and installed various absorbers and bass traps. But I have a major room resonance or room modes happening around 132Hz. Anyway, the point of my post is that I'm using a handy mp3 audio file that steps thru low frequencies in 1/3 octave intervals so you can easily figure out where your 'trouble' frequencies are. Here's the link to the SOS site webpage:
https://shar.es/abLoXx
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Re: nasty low resonace

Postby damartin » Mon Nov 02, 2020 9:03 pm

thank you all for your replies. very informative. my room (4m/5,5m) is not sonically prepared as a studio but it has two of its walls with polistyrene insulation.
cheers, Martin
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Re: nasty low resonace

Postby Sam Spoons » Mon Nov 02, 2020 9:33 pm

Is your room specifically (or at least substantially) your music room? If so then the very best investment you can make is in acoustic treatment (not 'soundproofing' I hasten to add). The polystyrene insulation will do nothing to help (any more than egg boxes) but a few properly constructed and places broad band absorbers and bass traps* will make a huge difference, imagine a £20 practice amp and a Fender Twin/Marshall stack or whatever and you'll get the idea...

* I spent around £350 in my room for materials to build DIY panels but could have done it for £250 if I'd been prepared to compromise the aesthetics. £500 would buy panels that look like art prints if it's a living room too.
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Re: nasty low resonace

Postby merlyn » Tue Nov 03, 2020 5:58 am

You could use Room EQ Wizard to see what's going on with your room.

https://www.roomeqwizard.com/

It could be the room or it could be something else. I had an annoying noise that only appeared when playing B on the 4th string. Something had come loose in my right monitor and tightening it fixed the noise. Fixing this involved tracking down exactly where the noise was coming from.
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Re: nasty low resonace

Postby blinddrew » Tue Nov 03, 2020 2:33 pm

That low C resonance is almost bang on the room mode for a 4m wide room...
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