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Exploring bass response in a less-than-ideal situation


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I have been experimenting with bass response using my digital phono preamp.  The situation is ...

 

  • small bookshelf speakers, 66Hz to 20kHz response
  • cartridge response, about 30Hz lowest
  • source - 78 records from 40s and 50s (swing, big band, jazz stuff)
  • variable bass turnover eq
  • variable very sharp cutoff "rumble" filter

 

So, I was getting a boomy sound, worse on some records, made worse by the habits of drummers in those days continually pounding the bass drum pedal.  First thing I did was play with the bass turnover, which for most 78s is supposed to be 250 Hz to 500Hz or maybe a bit more.  Sure enough, pushing down to 250Hz makes it worse -  but for those that are recorded using 250Hz turnover, you need that to get any usable bass from them.

 

Played with the rumble filter.   Cutting it off at about 75 Hz eliminates the boom.  Much better listening.  Subjectively, still enough bass to sound OK.  Hmm, suspiciously this is just above speaker bass response.  Could it be the bookshelf speakers achieve that 66Hz with a resonance peak?  Also, speakers and turntable are close enough together that I can spin the gain up and get a resonance feedback happening - that sounds about the same frequency.

 

So,  rumbly 78s, resonant bookshelf bass, and feedback at high volumes -maybe having an effect at lower volumes.    Probably something I just have to deal with.

 

So,  what bass response is needed anyway, to obtain a good sound?   75Hz is probably reasonable for small bookshelf speakers anyway?

 

 

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3 hours ago, aussievintage said:

So,  what bass response is needed anyway, to obtain a good sound?

 

I think this has been splashed on here at least once before.

 

330913d1271424698-frequency-range-chart-

 

 

Edited by Satanica
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2 hours ago, Satanica said:

I think this has been splashed on here at least once before.

 

Yes those are the actual frequencies of real things.  However, the recording medium is often capable of less than the full spectrum, as is the reproducing equipment.

 

Then there is a smaller spectrum we are happy to put up with, say in a car, when bass is and treble may be masked by car noises.  There is also historical recordings, even more limited but still able to sound OK.

 

It is surprising how far I can limit the spectrum, and still enjoy a "good" sound and enjoy the music.  I play some of these 78s with the filters set to 75Hz - 6kHz in order to cut out rumble and surface noise.

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13 minutes ago, aussievintage said:

Yes those are the actual frequencies of real things.  However, the recording medium is often capable of less than the full spectrum, as is the reproducing equipment.

 

Of older recordings yes but no excuse for not so old recordings.

 

13 minutes ago, aussievintage said:

It is surprising how far I can limit the spectrum, and still enjoy a "good" sound and enjoy the music.

 

I have a JBL Boombox ($400) and I enjoy the "good" sound from it and (always) enjoy the music from it just as long as I don't cram it in a tight space and then the bass goes out of balance.

It think Medium Fidelity (Mid-Fi) is all one needs to enjoy music.

High Fidelity is more than just enjoying the music; it's a hobby.

Edited by Satanica
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The MAJOR influencing factor for bass response is the room, you can do lots of DPS tweaking but this will do nothing to tame room modes.

 

Play a 100Hz tone and walk around the room you will hear it get louder and softer depending where you are in the room. The worst place is in the corners of the room there the tone will be loudest.

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3 hours ago, Warren Jones said:

The MAJOR influencing factor for bass response is the room, you can do lots of DPS tweaking but this will do nothing to tame room modes.

 

Play a 100Hz tone and walk around the room you will hear it get louder and softer depending where you are in the room. The worst place is in the corners of the room there the tone will be loudest.

 

True.  I bet there are room resonances influencing the situation.

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14 hours ago, aussievintage said:

 

True.  I bet there are room resonances influencing the situation.

 

Yes and no offence and you probably already know this but at the moment you're just working around the problem rather than trying to fix it.

Have you considered some form of EQ?

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2 hours ago, Satanica said:

 

Yes and no offence and you probably already know this but at the moment you're just working around the problem rather than trying to fix it.

Have you considered some form of EQ?

 

To remove the resonant frequency?  Well that's effectively what I am doing with the rumble (high pass ) filter set 75 Hz.  I suspect the resonance is near the speaker resonance which appears to be about 60 to 70Hz.  As there's nothing reproduced below that (the speaker's minimum freq response, then all I am removing is the 60 to 70 or 75Hz notch.

 

Of course this works well, and it's what led me pondering how much I will miss the bass below that.  It must be something many bookshelf speaker owners have to think about.

 

of course I could add a sub, but is overkill for this system.

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3 minutes ago, aussievintage said:

 

To remove the resonant frequency?  Well that's effectively what I am doing with the rumble (high pass ) filter set 75 Hz.  I suspect the resonance is near the speaker resonance which appears to be about 60 to 70Hz.  As there's nothing reproduced below that (the speaker's minimum freq response, then all I am removing is the 60 to 70 or 75Hz notch.

 

Of course this works well, and it's what led me pondering how much I will miss the bass below that.  It must be something many bookshelf speaker owners have to think about.

 

of course I could add a sub, but is overkill for this system.

 

I suspect you have a 60Hz room mode.

Your speaker won't just stop at 66Hz but rather will roll off .

But all just speculation until you do an in room speaker measurement.

 

There is plenty of bass is music below 75Hz.

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5 minutes ago, Satanica said:

 

I suspect you have a 60Hz room mode.

Your speaker won't just stop at 66Hz but rather will roll off .

 

Normally fairly fast though.

 

6 minutes ago, Satanica said:

But all just speculation until you do an in room speaker measurement.

Don't really have the equipment - and it's an office, not a sound room, so probably not worth it.  My main systems are in other rooms.

 

6 minutes ago, Satanica said:

There is plenty of bass is music below 75Hz.

 

True,  but not so much on the old 78s.  That said, I do play old microgroove monos on this equipment and they certainly deserve a better response.

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