Filter to Immitate Gramophone

Tim Wescott <tim@seemywebsite.com> writes:
> [...]
> And nonlinear effects, to, I would imagine.
>
> Altogether it would be an interesting challenge, particularly if you
> wanted to mimic _different_ gramophones and recording equipment.

By the way, here are a couple of recordings kindly made available
by Serge Auckland.

  http://audiopages.googlepages.com/otherstuff

You'll have to scroll down a bit to get to two mp3 links of
his gramophone recordings.
-- 
%  Randy Yates                  % "Maybe one day I'll feel her cold embrace,
%% Fuquay-Varina, NC            %                    and kiss her interface, 
%%% 919-577-9882                %            til then, I'll leave her alone."
%%%% <yates@ieee.org>           %        'Yours Truly, 2095', *Time*, ELO   
http://home.earthlink.net/~yatescr

Do not forget adding some scratches, the click(s) for each turn of the 
record.

And sometime you need to push the arm it you got stuck in same groove. 
(I know there is only one groove on each side ;-)

-- 
Christen Fihl
http://HSPascal.Fihl.net/

In article <1188239338.408481.89130@50g2000hsm.googlegroups.com>, 
ghuang@comcast.net says...
>
>
>I wonder if there exist some spec or transfer function of a filter
>that would immitate the responce of an old gramophone or 78s. I am
>retrfitting an old gramophone with modern mp3 electronics but like it
>to sound more "authentic".
>

I would start here:

http://www.victor-victrola.com/Victrola%20Horns.htm

As other posters have noted, you may want to add noise, nonlinear 
distortion, and clicks if you really want the simulation to be 
believable.

On 2007-08-28, Randy Yates <yates@ieee.org> wrote:
> Tim Wescott <tim@seemywebsite.com> writes:
>> [...]
>> And nonlinear effects, to, I would imagine.
>>
>> Altogether it would be an interesting challenge, particularly if you
>> wanted to mimic _different_ gramophones and recording equipment.
>
> By the way, here are a couple of recordings kindly made available
> by Serge Auckland.
>
>   http://audiopages.googlepages.com/otherstuff
>
> You'll have to scroll down a bit to get to two mp3 links of
> his gramophone recordings.

I have no great insight into solving your problem, but it's obvious that
all sorts of things are going on here which give the gramophne its 
characteristic sound.

1. It's certainly got weak response to low frequencies.
2. There is a fair amount of hiss, which you could probably characterize
   with a bit of work. 
3. There is a fair amount of popping.
4. I'm curious if the noise is correlated to the rotational speed of 
   the gramophone...
5. It's pretty clear that certain frequencies result in a resonant buzz.
   

Neat!

	Mark

Thanks for all the suggestions and comments. I guess I will start with
the "linear" part - frequency or impulse response, then noise and
pops. For non-linearity, I might start with a threshold - above the
threshold, the output follows a polynomial curve. There is also a
partition issue for linear filtering. Some filtering (ie. band-
limiting) will be before the NL operation and some (ie. resonance),
after. The good thing is that the project does not require any special
DSP hardware. I can simply convert CD data to linear PCM wav files, do
whatever I need on a PC, then convert the processed samples to mp3 for
playing.