Anyone analysed acoustics.....?

Pbassred · #1 06-08-2006, 09:27 AM

I read the FAQs and searched so don't throw rocks ok?

Has anyone ever carried out a technical investigation into the sonic differences between a double bass and and electric Fretless (lets leave the frets out for now!). Obviously they sound different, but where does that come from?

Does the DB have a faster decay? More low Fequencies? Harmonics from the wood (which?), does it echo? Does the Electric have a more even (and less natual) frequency response?

Ok go!

gomez hacienda · #2 06-08-2006, 09:48 AM

I don't think you need a technical analysis. You could do scientific studies, but one's ear is far better, as far as the real world.

Acoustics do have all those qualities you mentioned. Some are dictated by the strings you use...then there is the construction of the bass, be it carved or laminate or hybrid...then there's age and so on, ad ifinitum.

I have played lots of EBs and also own an EUB as well as my UB. Funny how years ago, I always tried to get my Fenders to sound like UBs. There's no substitute when it come to moving all that air. I think that's what it really comes down to.

gomez

Pbassred · #3 06-08-2006, 11:32 AM

I know I don't NEED a scientific analysis, and I do have ears. Obviously the sound comes from the construction. I was really interested if anyone had quantified what the difference is.

DrBassie · #4 06-08-2006, 11:38 AM

The same reason and electric guitar doesn't sound like an acoustic....

Alex Scott · #5 06-08-2006, 02:45 PM

If you were looking at the two side to side you might say this about the Double Bass:

Strings are longer, and have more audible harmonics
Top moves more, slightly changing string length
Body is hollow
wood is different
method of playing is different
everything else is different too.

jmpiwonka · #6 06-08-2006, 03:12 PM

Quote:

Originally Posted by Alex Scott

everything else is different too.

might be easier to say, is there anything that is actually similar besides the tuning?

Pbassred · #7 06-08-2006, 03:24 PM

No you missunderstand the question. I know where the differences come from. I understand what the differences are in the construction and technique.
what I am asking is about differences in the audio spectrum and envelope.

Alex Scott · #8 06-08-2006, 03:30 PM

No, really, strings vibrate in fractions, so as a whole, as a half, as thirds, as quarters, fifths etc.

A longer string makes a more audible upper frequency. That is the throaty mid range sound you hear, and higher ringing.

As the string vibrates, it stretches and contracts. That part is similar to electric bass, but on the upright the top moves, so the stretching and contracting is more evident. It almost sounds like Vibrato sometimes.

Those are two things I see immediately from scientific observation.

If you have a crt TV or monitor, you can watch the string under the constant strobe light of the screen and see these things for yourself.

Lower input into the string has a more even response, and sounds more even, pulling the string very hard makes the change in impact and decay more apparent.

I have no spectrum analysis, I prefer to think of all this as art meets quantum physics in action.. Good luck figuring out what you want to figure out.

Pbassred · #9 06-08-2006, 03:51 PM

No you missunderstand the question. I know where the differences come from. I understand what the differences are in the construction and technique.
what I am asking is about differences in the audio spectrum and envelope.

jmpiwonka · #10 06-08-2006, 03:59 PM

Quote:

Originally Posted by Pbassred

No you missunderstand the question. I know where the differences come from. I understand what the differences are in the construction and technique.
what I am asking is about differences in the audio spectrum and envelope.

you already said that.
Alex told you the double bass had stronger harmonics and therefore more overtones. that means the double bass will have a larger "audio spectrum"...i don't know what you mean when you talk of the "envelope"...i use my ears to decide what sound i like rather than scientific instruments and studies...perhaps you should do a little googling if you're bored, fella.

Marcus Johnson · #11 06-08-2006, 04:34 PM

Or take Carleen Hutchins out for lunch.

jsbarber · #12 06-08-2006, 07:30 PM

He wants to know how the waveforms differ. Like if he graphed the signal and analyzed it to characterized the difference in the signal. Eg. spectral content, phase relationships, attack, decay... (By enveloped I think he is refering to a plot that connects the tops of the peaks together and the bottoms of the valleys together.)

PBassRed - you might enjoy reading this:

http://iwk.mdw.ac.at/Forschung/pdf_d...ssertation.pdf

It probably also has a bunch of interesting references, if you're into that sort of stuff.

Cheers,

Jim

dguna · #13 06-08-2006, 10:10 PM

I've just plotted a really simple magnitude response plot of the frequencies of the UB and EB in steady state. Obviously the harmonics move over time, but the spectral envelope is relatively constant in steady state and I've just taken a frame of audio from steady state.

The arco UB shows a richer set of mid to higher harmonics with various resonances (peaks in the envelope) and these contribute to the perceptual 'richness' of the UB sound - compared to the EB which generally has a smooth monotonically decreasing envelope (i.e. no resonant peaks besides the first one).

The frequency response of the plucked EB and the pizz EB are quite similar spectrally, but the EB has a bit more higher harmonics. The main perceptual differences will primarily be in the temporal changes - UB pizz has shorter sustain than EB.

Hope this helps...

**Matthew Tucker** · #14 06-09-2006, 01:43 AM

Quote:

Originally Posted by dguna

I've just plotted a really simple magnitude response plot of the frequencies of the UB and EB in steady state.

What does that mean? How do you do that?

dguna · #15 06-09-2006, 01:50 AM

Well frequency analysis is typically done with an FFT (Fast Fourier Transform). You take a signal's time waveform and the FFT allows you to analyse the frequencies that make up the signal (in terms of sine and cosine waves).

I just did it in Matlab (software made by mathworks)...

**Matthew Tucker** · #16 06-09-2006, 02:02 AM

Yeah but what do you actually do? Do you play Blue Monk into a microphone and average the response? Do you poke a speaker in the f hole use a sine wave sweep? White noise generator?

dguna · #17 06-09-2006, 02:06 AM

I just took a recording of a double bass (single note played arco and pizz record with a neumann) and a recording of an EB (direct) and analysed the PCM waveforms. Nothing fancy... just to get a rough idea

alexclaber · #18 06-09-2006, 02:31 AM

Look how much less fundamental the upright bass produces!

Just goes to show that deepness of tone isn't about how much sub-bass you put out...

Alex

Pbassred · #19 06-09-2006, 05:51 AM

What is the FFT calibrated in? volts? DB? What was the note played?

It looks like peaks at 30, 70, 110, 200Hz. 30Hz is Sub where I live! Now I need to do the same for an electric fretless. - unless I'm lazy and let dguna do it on the same rig)

dguna · #20 06-09-2006, 07:49 AM

Its just in linear magnitude (but then on log plot) and I've normalised maximum to 1. It was just a quick plot i ran to observe the spectral envelope.

The note used for all is the low E on the bass at 41.3 Hz.