RIAA preamp help

Check it against....

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

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

"Daniele - Skrauso" a écrit dans le message de news: snipped-for-privacy@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.

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.

you're right..!

the

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

Thanx Daniele

"Daniele - Skrauso" a écrit dans le message de news: snipped-for-privacy@uni-berlin.de...

no

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.

cap.

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

Bye Daniele

de

quick

high

from the

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.