Some interesting Audio IC's (5-band EQ, preamp, compressor)

[davesisk]

Hey Folks:

I'm a newbie, but I ran across a few interesting audio IC's that seem like they'd be awefully useful.  Just wanted to post in case this isn't common knowledge and to see if folks think these might be useful for some other types of circuits, so let me know what you think.

5-band EQ on chip:  Rohm BA3812L

Mic preamp on a chip:  Analog Devices SSM2019

Preamp and compressor on a chip:  Analog Devices SSM2166

BA3812L EQ chip:  I've looked at the data sheet for this one, looks pretty cool.  Again I'm a newbie, but the sample circuit looks pretty straightforward, just wire up capacitors and variable resisters.  I'd assume this might make easy fixed filters, crossovers, etc. as well.  I'm wondering if you could perhaps design an easy 5-input mixer around this as well?

SSM2019 preamp:  Easy preamp, only needs a variable resistor for gain control.  Could you design a distortion circuit around this guy?  I noticed the data sheet said it could also be used as a summing amp...presumably this means you could do an easy mixer circuit or blend circuit for effects...thoughts?

SSM2166 preamp/compressor: Presumably an easy compressor design possible here.  Could you design a compressor + distortion circuit around the preamp/input buffer and compressor section of this circuit, or possibly a compressor + effects loop blender?  (Or is the input buffer really only suitable as an input buffer and nothing functionally more?)

Let me know your experienced thoughts on these!

Dave

[snoof]

i think that the 2166 is only available in SMD format.  check out Q&D compressor over at GEO.  there's a fuzz here that uses the EQ chip.

http://www.beavisaudio.com/

[Ben N]

Correction: the Q&D is at AMZ (www.muzique.com), and there are several threads about it here, including reviews (very positive) and mods. Small Bear may still have some thru-hole SSM2166s.

There are actually a couple of mic-preamp-on-a-chips out there--I doubt that their fidelity is particularly useful to designing a distortion, any more than other opamps and audio amp chips, and (not having looked at the datasheet) I'd guess that their input impedance may be low for guitar use. There has been some discussion around here about building mic preamps from time to time.

That eq looks interesting, though.

Ben

[snoof]

D'oh.  Thanks for the correction

[davesisk]

i think that the 2166 is only available in SMD format.  check out Q&D compressor over at GEO.  there's a fuzz here that uses the EQ chip.

http://www.beavisaudio.com/

Hey...not sure I know what an SMD is?  Surface-mount device?  I assume that means you couldn't use it on a normal PCB or breadboard?

Dave

[CGDARK]

Yes, it is not a thru hole device. It is mounted on the surface of the PCB, not through holes in it.

CG

[Ben N]

Right you are. SMD parts are much smaller than the old-fashioned thru-hole stuff. Ever look at the PCB of a Danelectro mini-pedal? All SMD. They also solder to pads on the comonent side of pcb rather than having leads that go through holes to solder on the other side. As for whether SMD is useful for DIY, reasonable people differ. Personally, my hand is not steady enough (from exerience). Others here do it and swear by (not at) it. There are also not many DIY PCB layouts for SMD, so you'd pretty much have to roll your own.

Ben