RIAA Curve Distortion EQ

[WGTP]

For those of you old enough to remember, vinyl 331/2 rpm records are "mastered" with substantial bass/mid roll off.  It is a standardized curve used on all 45"s as well.  Nothing magic about it, although audiophiles go nuts worrying about the EQ section in their phono pre-amp.

In the FBL it acts in reverse.  It has multiple roll off points of 500 and 2100Hz.  Modding the circuit is strongly encouraged.

I PROBABLY NEED TO LABLE THIS AS A PRELIMINARY DESIGN SINCE IT ISN'T ON THE BREADBOARD AT THIS POINT IN TIME.   

http://www.aronnelson.com/gallery/main.php/v/WGTP/RIAA.GIF.html?g2_imageViewsIndex=1

Cool calculator  http://www.kabusa.com/riaa.htm

[slacker]

Very cool, I'll give it a try.

[Ben N]

Dave Barber says that it is the key to the Direct Drive--using an RIAA-style eq at the end to restore the bass. (Although the DD is not exactly a bass-heavy pedal, it is less bass-starved than a tubescreamer.

Looks like a nice implementation.

[DougH]

I designed a pedal with a bass compensation stage on the output. It works real well.

Thanks for the RIAA circuit!

[WGTP]

It may have been Dave that mentioned that here on the forum.  I couldn't remember who it was.  There are also op amp FBL versions, but with all the gain 2 op amps produce, I figured passive should work.  You can come up with a variety of curves with the calculator.

Doug, are you talking about this? http://www.aronnelson.com/gallery/main.php/v/WGTP/Sweet16.gif.html?g2_imageViewsIndex=1

It is a cool tone control.

[DougH]

Doug, are you talking about this?

No, it's something I did recently that I'm keeping for myself. The bass-comp is an active op amp stage.

[Caferacernoc]

Ever since I learned that most boutique overdrives have an unused half of an opamp chip in them I am quite surprised that having some kind of "bass restoration" isn't more common. It seems so obvious.

[DougH]

I agree it should be obvious. But there are a number of "boutiquers" who just copy stuff without understanding what they are doing.

[WGTP]

I guess you could do the same thing with other types.  For example, the famous Rat Double Leg FBL EQ.  Or, the one in the Blues Breaker, or the Std. Dist +/TS 4.7k/.047uf circuit.   

[puretube]

I agree it should be obvious. But there are a number of "boutiquers" who just copy stuff without understanding what they are doing.

semper idem...