RIAA preamp help

[Daniele - Skrauso]

Hi all,
I found this simple circuit http://sound.westhost.com/p06-fig2.gif to
preamplifly a phono source.
Do you think it's good? I don't need extreme quality.. just a well-working
device

Thanx
Daniele

 

[Jim Thompson]

On Sun, 18 Jul 2004 22:15:39 +0200, "Daniele - Skrauso"
<re_di_picche@infinito.it> wrote:

Hi all,
I found this simple circuit http://sound.westhost.com/p06-fig2.gif to
preamplifly a phono source.
Do you think it's good? I don't need extreme quality.. just a well-working
device

Thanx
Daniele

Check it against....

http://www.tanker.se/lidstrom/riaa.htm

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Daniele - Skrauso]

Check it against....

http://www.tanker.se/lidstrom/riaa.htm

thanx man..
I noticed that riaa curve cuts heavily high frequences.. I tried a quick
simulation (generic opamp) with pspice and I got a flat response on high
frequences!
So I think I'll have to build another circuit..

Thanx
Daniele

 

[Fred Bartoli]

"Daniele - Skrauso" <re_di_picche@infinito.it> a écrit dans le message de
news:2m0670Fhm6d7U1@uni-berlin.de...

Check it against....

http://www.tanker.se/lidstrom/riaa.htm

thanx man..
I noticed that riaa curve cuts heavily high frequences.. I tried a quick
simulation (generic opamp) with pspice and I got a flat response on high
frequences!
So I think I'll have to build another circuit..

Thanx
Daniele

Why ? It shouldn't : there's the 820R/82n time constant at the output.
You must have made a mistake in your sim.

When doing this circuit, just think to change the 10u and 22u caps from the
minus inputs to the ground side (less parasitics).

Thanks,
Fred.

 

[Daniele - Skrauso]

Why ? It shouldn't : there's the 820R/82n time constant at the output.
You must have made a mistake in your sim.

you're right..!

When doing this circuit, just think to change the 10u and 22u caps from
the
minus inputs to the ground side (less parasitics).

what do you mean for change? you mean the value or the capacitor type, ie no
electrolytic?

Thanx
Daniele

 

[Fred Bartoli]

"Daniele - Skrauso" <re_di_picche@infinito.it> a écrit dans le message de
news:2m2fsqFi3ltpU1@uni-berlin.de...

Why ? It shouldn't : there's the 820R/82n time constant at the output.
You must have made a mistake in your sim.

you're right..!

When doing this circuit, just think to change the 10u and 22u caps from
the
minus inputs to the ground side (less parasitics).

what do you mean for change? you mean the value or the capacitor type, ie
no
electrolytic?

Thanx
Daniele

No, just exchange the grounded resistor of the feedback network and the cap.
i.e. :


minus input ------- resistor ----- cap ----GND

instead of

minus input ------- cap ----- resistor ----GND


The minus input of opamps is sensitive to capacitive parasitics to ground
(this adds one pole with the feedback resistors) and it's good practice to
reduce this parasitics as much as possible. Otherwise, from the circuit POV,
there's no difference.


Thanks,
Fred.

 

[Daniele - Skrauso]

No, just exchange the grounded resistor of the feedback network and the
cap.
i.e. :

thanx a lot.
I also found the error in the simulation and now it's all working

Bye
Daniele

 

[Watson A.Name - \"Watt Su]

"Fred Bartoli"
<fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote in
message news:40fb8d0f$0$29370$626a14ce@news.free.fr...

"Daniele - Skrauso" <re_di_picche@infinito.it> a écrit dans le message
de
news:2m0670Fhm6d7U1@uni-berlin.de...
Check it against....

http://www.tanker.se/lidstrom/riaa.htm

thanx man..
I noticed that riaa curve cuts heavily high frequences.. I tried a
quick
simulation (generic opamp) with pspice and I got a flat response on
high
frequences!
So I think I'll have to build another circuit..

Thanx
Daniele


Why ? It shouldn't : there's the 820R/82n time constant at the output.
You must have made a mistake in your sim.

When doing this circuit, just think to change the 10u and 22u caps
from the
minus inputs to the ground side (less parasitics).

What do you mean by 'think'?

The input and output capacitors are missing their plus sign, assuming
they're electrolytics. The positive on both is towards the 5532.

Thanks,
Fred.