Preamp response curve

Oliphant · 09:09 AM

I'm prototyping a preamp using a pair of OPA604's (buffer and gain stage) and I can't quite seem to get the response curve right. I first tried it with a perfectly flat curve and it sounded terrible and then with a shallow roll off that was -3db at 2kHz which sounded much better but still wasn't quite right.

Is there an industry standard frequency response for home audio gear? Or does anyone have any suggestions as to what the frequency response should look like?

jcx · 10th November 2009, 05:14 PM

preamp for what source?

Oliphant · 10th November 2009, 05:23 PM

It will be for a CD player and DVD player

AndrewT · 10th November 2009, 05:39 PM

i usually set the filters on power amps that have f-3dB @ 1.8Hz AND 200kHz.
I try for at least half an octave wider for a pre-amp, i.e <1.3Hz and ~300kHz.

Oliphant · 10th November 2009, 05:47 PM

Thanks for the info Andrew. I originally tried it completely flat between 3HZ and 150kHz and it sounded completely wrong, which lead me to believe that recording studios must manipulate the sound so that high frequencies are louder by comparison.

Maybe I'll use my signal gen and oscilloscope to see how other hifi amps respond

Oliphant · 12th November 2009, 05:48 AM

Update: embarrassing mistake, I had the filter backwards. Now with a filter that's -6db at 150kHz and the preamp sounds just fine

10th November 2009, 09:03 AM	#1
Oliphant diyAudio Member Join Date: Nov 2009 Location: Wellington	Preamp response curve I'm prototyping a preamp using a pair of OPA604's (buffer and gain stage) and I can't quite seem to get the response curve right. I first tried it with a perfectly flat curve and it sounded terrible and then with a shallow roll off that was -3db at 2kHz which sounded much better but still wasn't quite right. Is there an industry standard frequency response for home audio gear? Or does anyone have any suggestions as to what the frequency response should look like? Last edited by Oliphant; 10th November 2009 at 09:09 AM.

10th November 2009, 05:39 PM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	i usually set the filters on power amps that have f-3dB @ 1.8Hz AND 200kHz. I try for at least half an octave wider for a pre-amp, i.e <1.3Hz and ~300kHz. __________________ regards Andrew T.

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10th November 2009, 05:14 PM	#2
jcx diyAudio Member Join Date: Feb 2003 Location: ..	preamp for what source?

10th November 2009, 05:23 PM	#3
Oliphant diyAudio Member Join Date: Nov 2009 Location: Wellington	It will be for a CD player and DVD player

10th November 2009, 05:47 PM	#5
Oliphant diyAudio Member Join Date: Nov 2009 Location: Wellington	Thanks for the info Andrew. I originally tried it completely flat between 3HZ and 150kHz and it sounded completely wrong, which lead me to believe that recording studios must manipulate the sound so that high frequencies are louder by comparison. Maybe I'll use my signal gen and oscilloscope to see how other hifi amps respond

12th November 2009, 05:48 AM	#6
Oliphant diyAudio Member Join Date: Nov 2009 Location: Wellington	Update: embarrassing mistake, I had the filter backwards. Now with a filter that's -6db at 150kHz and the preamp sounds just fine

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