Low noise guitar pre-amp / ADC

[whygee]

High-end (used to be custom-only) guitars put the preamp/conversion IN
the guitar.

I use to remove all knobs from my guitars,
I see no point in having TWO volume controls in series
(one in the guitar, the other in the amp).
I don't use amps anyway.
Oh, and the "tone" knobs are also removed,
I love the bare sounds of each guitar.
My idea is that any sound alteration should be left to
post-production, after the sound has been recorded...

As a side effect, the removed knobs leave a few holes
in the guitar's body, where there is a little void,
that then acts as a resonant chamber.
So I have an old SANOX guitar that sounds
good with AND without amplification,
depending on the strings' quality.
With this model, the guitar is more versatile
without knobs than the original version...

yg

 

[Colin Howarth]

High-end (used to be custom-only) guitars put the preamp/conversion IN
the guitar. If you have a pot panel that's removable you're golden.
Else it's like arthroscopic surgery.

Oh. I'm good at that. I'd put switches where the pots are to change
between series and parallel wiring of the humbuckers for example.

All the previously-mentioned detractors like noise from pots,
connectors, cable capacitances etc. are avoided.

Sounds good.

Some my recording-engineer friend talked about had both magnetic
pickups and microphones in the same guitar.

Low Noise would be great for classical guitar. But a LOT of the
guitar noises that make money are "Down in the noise level" anyway

Usually the big problem is the darn cables, hum pickup, ground loops
etc, external to the guitar. My friend has installed 120VAC "Balanced
to ground" power in his professional studio, which greatly reduces
60Hz pickup in lots of places. And a common-point ground/neutral
connection to a 6 inch wide copper strap that runs through the floor
slab and stubs up in the equipment locations. Recently this approach
is even IN the Electrical Code. Previously, he was fortunate in that
he was in remote Vermont, 100 miles from the nearest electrical
inspector...

I don't have a problem until I connect my MacBook Pro to mains...

24 bits might be 'excessive', but "Moderation In the Pursuit Of Clean
Signals is Not a Virtue". (Was that Barry Goldwater??)

 

[Colin Howarth]

"Colin Howarth is a very sick man "



** Why don't you just **** off and die ??



.... Phil

Dear Phil,

have you noticed that your replies are becoming less and less helpful?



Unfortunately, for you, you cannot escape this thread! You are forced to
type more and ruder replies, increasing your blood pressure, wasting
your free time and making you look ever sillier.

I feel a little bit sorry for you, but I'm afraid your stuff is just too
amusing to read, to let you escape.


--colin

 

[Phil Allison]

" Colin Howarth is a Very sick man "

** Why don't you just **** off and die ??


Dear Phil,

** Go drop dead, you vile piece of shit.

Unfortunately, for you, you cannot escape this thread!

** Watch me.

I feel a little bit sorry for you,

** I have not one tiny, little bit of sympathy for trolling psychotic morons
like

YOU - you FUCKING asshole !!!!!!!!!!!!!!!!!!


May the fucking mad whore who bred a piece of scum you and the donkey
brained
retard that fucked her to cause you to to exist burn in hell.

Cancer is too good for scum like you.



..... Phil

 

[Ralph Barone]

Perhaps Paul (and certainly I) are a victim of that

A little learning is a dangerous thing; drink deep, or taste not the
Pierian spring: there shallow draughts intoxicate the brain, and
drinking largely sobers us again.

thing.


I'm surprised no-one has yet said "what's this obsession with low noise?
An E-guitar isn't a Stradivarius!"

The whole issue is (or I'm making it) a bit more complicated than it may
seem.


Pro audio (not that I'm a pro) is mostly digital these days. My digital
audio workstation (aka computer) likes 192 kHz 24bit input. That may
seem like overkill considering that I don't even hear up to 20 kHz
anymore BUT...

Guitar pickups (resistive/inductive) in combination with cable
capacitance have their own resonance, distortion and filtering
characteristics (ie. sound) and, in the old days, these even change
depending on what effects boxes you plug into, due to varying load
impedance.

However, now, ALL the signal modification (including filtering and
distortion) is supposed to be going on in the computer using amp
modelling, equalisation, artificial distortion etc.


If I'm sampling 24 bits, I'd like the input signal to be as clean as
possible. The ADC wants 5.6 Vpp (full scale). That's differential input,
so each signal is supposed to be 2.8 Vpp, ie. around 1 V rms.

The pickups output around 300 mV rms.

1 bit of that is, ummmm, about 18 nV.

-> low noise amps, pre-amp as soon as possible.


--colin

Plug your guitar into a scope and whack the hell out of the strings.
You might be surprised what sort of peak voltages you can get.