Macca's Lash Up 2: Lash Harder

[Macca]

Not going to get me down to 20 Hz in the bass though. A subwoofer with some DSP would do it easy. Not massively keen on bringing a sub in though, bit like Roy Hodgson.

[User211]

Had Peter (Petrat) round here this morning, he brought me a geetar (which I might show you tomorrow if you are all good).

Anyway long story short he had a bit of a listen to it, (which is probably slumming it a bit for him given what he uses himself); He reckoned the ported bass is the weak point ( 'a bit soft and fuzzy)', and that the lack of holographic imaging could be down to the lack of bass below 40 HZ (the port being tuned quite high, meaning bass rolls off fast after 40 Hz) and that a proper sub that will do 20 Hz would help retrieve the ambient cues lurking in the deep bass.

He makes a very valid point I think. It doesn't actually matter if there are musical frequencies down there on the recording, it still affects the illusion of reality.

I have all the bits to build such a thing lying about, might think about it.

I've taken a few temporal FFTs of me playing my acoustic guitar. Amazingly it bangs out quite significant LF. Will post it to illustrate later if I can find it.

[User211]

The level of white represents the level of energy the guitar is producing. The y scale is 0 to 20KHz. Just LOOK at the amount of LF the humble acoustic (Gibson SJ200 Custom Cutaway) is producing! I was amazed when I saw it. It is all body resonance from the acoustic's body. A double bass is huge and will produce FAR MORE.

The bottom pic is simply a zoom in to show the bass region. The y scale is 0 to 4K. The s/w wouldn't let you zoom in any more, but for some chords you can quite clearly see energy right down to the bottom of the graph at the point the chord is struck.

When you think about it, the low E string fundamental on an acoustic is about 82Hz. There's going to be plenty of harmonics below and above it. So, if your system can't hit 20 odd Hz you are defo missing information just trying to replay something as crude as an acoustic.

Food for thought given your previous post.

[Macca]

I agree, I'm starting to see it as an area I need to work on. I'm putting all operations on hold for the winter now. What I have right now is pretty good. If it wasn't my hobby to keep trying to improve it, I would be happy as it is. But a man should have a hobby

[User211]

Actually, strumming my guitar now using my phone's guitar tuner s/w shows the E chord as E1 at 41 Hz. E string as E2 at 82Hz. But it also draws a little histogram showing info below the fundamental of the E1 E chord with significant amplitude, which backs the above up.

[Macca]

The fundamental can't be 41 hz though, from a six string. And you have ambient noise to consider. I don't know enough about it, put simply.

[User211]

Put it this way, the guitar tuner looks for the highest amplitude and checks what the frequency it is at using an FFT.

I just imagine the 6 strings as one, and see that as the fundamental of the chord, as it were, by the algorithm expressed by the previous sentence.

The histogram shows nothing on the guitar tuner when no chord is struck. But a few segments below the 41 Hz fundamental when it is struck therefore ambient noise is irrelevant i.e. it is at too low a level to register.

(Sorry - had to correct the last sentence I typed in jibberrrisshhhh).

[Macca]

As I say I don't have the knowledge to comment. Logic, and some experience tell me you do need flat down to, ideally, 20 Hz, is essential if you want to get absolutely everything most recordings have to offer. Reading around this seems to be confirmed by those who have gone there already.

[struth]

Actually, strumming my guitar now using my phone's guitar tuner s/w shows the E chord as E1 at 41 Hz. E string as E2 at 82Hz. But it also draws a little histogram showing info below the fundamental of the E1 E chord with significant amplitude, which backs the above up.

E1 is 41.2hz so your pretty much bang on there. E2 is 82.41hz. Might add that E1 is a second bottom string of a 5 string bass guitar. E2 is bottom of 6 string guitar

[Macca]

Some experimenting with speaker positioning. This is with the speakers as far apart as possible (about 6 feet from inside edge to inside edge). Stereo image is deeper and wider, problem is this creates an imbalance at the listening position, not sure why. Tweaked the balance at the amp which is not satisfactory as it smears the image and vocalists no longer seem rock solid and dead centre. Not sure what is going on here, but close up with balance equal there is not a problem, 20 feet back there is.