Re: RIAA phono eq curve

2009-03-21 Thread Phil
On Thu, Mar 19, 2009 at 3:23 PM, Philip Schleihauf
 wrote:
> On Thu, Mar 19, 2009 at 9:21 AM, sue...@empire.net  wrote:
>>
>> >
>> >
>> >
>> >Original Message:
>> >-
>> >From: Sean Corbett seanbutnothe...@gmail.com
>> >Date: Thu, 19 Mar 2009 08:56:36 -0400
>> >To: ubuntu-studio-users@lists.ubuntu.com, p...@magnustudios.com
>> >Subject: Re: RIAA phono eq curve
>> >
>> >
>> >> --
>> >>
>> >> Message: 3
>> >> Date: Wed, 18 Mar 2009 12:31:54 -0400
>> >> From: Phil 
>> >> Subject: RIAA phono eq curve
>> >> To: Ubuntu Studio Users Help and Discussion
>> >>        
>> >> Message-ID:
>> >>        
>> >> Content-Type: text/plain; charset="iso-8859-1"
>> >>
>> >> Hey,
>> >>
>> >> I've got a large collection of vinyl records I need to record onto CD, or
>> >> some other digital format. I've got a stereo with phono inputs, so I
>> could
>> >> use that for the preamp, but I'd rather take the phono player directly
>> into
>> >> my firebox and correct the EQ digitally.
>> >>
>> >> I've done a bit of research on what I need to do. I need a really
>> accurate
>> >> diagram of the RIAA phono curve. The best I've found so far is the one at
>> >> wikipedia, http://en.wikipedia.org/wiki/File:RIAA-EQ-Curve.svg . It's
>> only
>> >> got the markings for 20, 1000, and 2 Hz. I guess it's got to be a
>> >> logarhythmic graph so I should be able to use it to acurately find the
>> other
>> >> frequency levels.
>> >>
>> >> What I'm hoping for is that someone has already done this and has made a
>> >> preset for a ladspa plugin, or for jamin. Does anyone know of this?
>> >>
>> >> If not, I'll make mine publicly available when I do it.
>> >>
>> >> Thanks,
>> >>
>> >> Phil
>> >> p...@magnustudios.com
>> >
>> >Audacity has the RIAA curve built in... Just record your vinyl, select
>> >the whole recording, and go to Effect>Equalization... and select
>> >'RIAA' from the 'Select Curve' dropdown at the bottom.  I've never
>> >done this myself though, so I can't vouch for its accuracy.
>> >
>> >--
>> >Sean Corbett
>> >
>>
>> Also nicely done RIAA kit from Elliot Sound:
>>
>> http://sound.westhost.com/project06.htm
>>
>> 
>> myhosting.com - Premium Microsoft® Windows® and Linux web and application
>> hosting - http://link.myhosting.com/myhosting
>>
>>
>>
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>
>
> Alright thanks for all the responses.
>
> In terms of the noise from the firebox: I'm going to try it out, and
> see how good it is. I'm going to hook up the phono and look at the
> noise I get through jamin - I think it's mostly high-frequency, so it
> shouldn't be to much of a problem after the RIAA curve is applied. If
> it's not working, I'll just run the signal through my stereo, which
> has phono inputs.
>
> All the other info is useful. Although using audacity looks easy, I
> think if the firebox works out I will be using ardour, probably routed
> through JAMin for the hdEQ. That way I can just stick in the CD track
> markers and go right to a CD. If I do this I'll make my .jam file
> publicly available somewhere so other people can use it too.
>
> That RIAA kit looks really neat. Maybe I'll have a go at it when I get
> some time.
>
> Thanks!
>
> Phil
>

...sorry for using different email addresses, I always forget to check
which one I'm sending from.

anyway did some digging:
Turns out that you get an RIAA curve with the jamin source code. That
makes it even.

I also found this though:
http://www.mail-archive.com/linux-audio-...@music.columbia.edu/msg19348.html

"Second, the general 1/F slope of the RIAA curve when combined with
cartridge equalisation should produce a -90 degrees phase shift
over most of the audio band. When you synthesize such a curve with
a multiband EQ, you will not have that phase shift, and any percussive
or transient sounds will be affected. You can easily hear this on
some instruments.

It's quite simple to make an RIAA filter with for example two
first order lowpass LADSPA plugins. Put them in parallel, set
one to 50 Hz and the second to 2120 Hz. Mix the outputs in the
ratio 9 to 1, and the result will be a *perfect* RIAA filter."

I think I'll do some tests with JAMin RIAA vs this guy's RIAA suggestions.

There's quite a bit of info on that thread to sort through, but I
think I'll have enough info to get this going.

Thanks,

Phil
p...@magnustudios.com
http://magnustudios.com

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Re: Jaunty -RT testing

2009-03-21 Thread Joseph Reagle

As an aside, while I wasn't comfortable with with Jaunty RT oddness, I don't 
think NaturallySpeaking in a VirtualBox Machine requires RT, just low-latency. 
So I actually tried Intrepid again and built a kernel [1] with the following 
settings. I'm also using the new vbox 2.2b1 [2] -- with much improved USB 
performance -- and things seem quite good.

CONFIG_MCORE2=y
# CONFIG_NO_HZ is not set
CONFIG_HIGHMEM64G=y
CONFIG_HZ_1000=y
CONFIG_HZ=1000
# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
CONFIG_PREEMPT=y
# CONFIG_PREEMPT_RCU is not set
# CONFIG_PREEMPT_TRACER is not set
# CONFIG_DEBUG_KERNEL is not set


[1]:https://help.ubuntu.com/community/Kernel/Compile#Alternate%20Build%20Method:%20The%20Old-Fashioned%20Debian%20Way
 
[2]:http://forums.virtualbox.org/viewtopic.php?f=15&t=15525&sid=121f0f57ec7b7bf0bf65a0e18cd97bf5

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