Reverse RIAA stage

[datape]

My hifi is a little pioneer mini system thing that only has a phono input. No line in. So I need to cobble together a reverse of the RIAA phono stage to take the output of my powerbook into the hifi. Is this possible? Any thoughts appreciated.
Cheers!!!
Dave

 

[datape]

Think i've solved the problem. Using the EQ in iTunes to an approximate reverse match of the RIAA curve and turning the output down on the powerbook gives me a clear signal on amplifiers phono input. I'll try it properly when I get home. Cheers for looking!!

 

[sismofyt]

always do this :green:

first link i got:

http://sound.westhost.com/project80.htm :wink:

 

[datape]

Interesting link thanks. I'll see how the itunes EQ bodge works first...

 

[sismofyt]

i made rod's little gadget for girl friend in the same boat as you. it works very nicely. i jammed the lot into a couple of large rca plugs ..

the itunes thingy would be a not so good solution. first, i'm sure that eq is a pos, second you'll be putting out a -30dB signal from your laptop's onboard converters. i'm sure they suck equally hard

just get those few passive components. much better. you can also tune the freq response to something that suits you better than the riaa standard, if you like

 

[shabtek]

open up the box and pick-off the signal path after the phono stage...dc decouple with a cap.

 

[sismofyt]

there probably isn't even a line stage in there, you can just go straight to the volume pot through a cap ..

that is, if you don't have a tt :wink:

 

[rafafredd]

http://sound.westhost.com/project80.htm

Nice smd layout!

You could also use the itunes EQ, and use an attenuator to bring the signal down without loosing so much signal-noise ratio and making the crap sounds bad. It would be really easy to make an attenuator with just four resistors for two channels.

 

[datape]

I'd thought of using just the resistors. How would I determine the values?

thanks

 

[rafafredd]

how much attenuation do you need? Probably the computer output is -10dBv level... -20dB attenuation would probably work just fine. So let´s say 10k series with a 1k shunt.

If you need -30dB, change 10k to 33k and keep 1k shunt.

 

[datape]

Thanks!!! I'll try those values.

I may also try that diagram.. cheers!!!