First amp project

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
R

RoadToNever

Member
Joined 2011
Thanks, ethanolson. Good to know that it's a good Cmoy design. Regarding DC offset, I plan to use DC wall power exclusively and If it's good(not great) to NwAvGuy's standards it's fine for now. I can't seem to find a PCB or perfboard/stripboard layout for that particular circuit. You wouldn't happen to know?
 
D

Davey

Account Closed
Joined 2001
Well, you can buy "wall-warts" that provide +/- DC power......

Roadtonever,

The modified Cmoy is a nice, simple project but why don't you consider building the O2 amp sans batteries? It's simple too and thanks to RS and terrific group of DIY suppliers the parts/pieces/pcb are easily available.

Cheers,

Dave.
 
D

ddietz

Member
Joined 2011
For the headphone distribution, check out the schematic. It is incredibly simple. Inverting voltage amp with gain of 10 for each channel. Uses a standard virtual ground split by resistors with smoothing capacitors. All channels are identical so you can easily duplicate Channel 1 however many times you need, 2, 6, 12, whatever.

Probably costs about $2 a channel if you use nice opamps. The dual audio log pots for level is the most expensive part. Cheap ones can be a couple bucks each. They also don't have to be 100K either, afaik, 10K-20K is fine.
 
sgrossklass

sgrossklass

Member
Joined 2004
stephan.win31.de
I'd guess the volume pots in the PAiA design are 100k linear types, with the inverting opamp circuit's 10k input resistance being used to make response approximately log... old trick (see ESP project 1). I wouldn't call 100 ohms of output impedance "low" either.

I'd suggest a nice symmetric power supply (maybe O2-style if you can't find a transformer with a center-tapped output), LM317/337 based low-noise regulators (with an electrolytic at the adjust pin), and then clone an Apheared-47 style circuit a few times (using reasonably beefy opamps - 5532s are kinda OK but JRC/NJR 4580s and especially 4556s can provide more current). If super-high input impedance isn't required, a 10k volume pot is just fine and actually preferred.

Assuming the space is there and the higher parts count isn't an issue, amplifiers using a discrete A/AB buffer also are worth considering.
 
R

RoadToNever

Member
Joined 2011
I forgot to mention, low voltage capability would be a bonus for ocassional field use. Why would Paia talk about 8-600 Ohm compatability, they never heard of the 1:8 rule? I'm not skilled enough to follow through without a PCB or perf/stripboard layout. I'll look for Gyraf and SDS projects. sgrossklass, do you know of any projects that use the designs you mention?
 
Last edited:
R

rondr

Member
Joined 2011
RoadToNever said:
Found this: PAiA - 9206KP Headphone Distribution Amp Kit (International version - ships without 110V power supply), Headphone Distribution Amplifier, 9206KP Looks perfect (low output impedance) except that it has twice more outputs then I need right now. Still looking....
Click to expand...
This was published back in 1992 in Electronic Musician Magazine as "Build Your Own EM Headphone Distribution Amplifier." In the article there was the schematic as well as the circuit board layout. It was the first electronic project I decided to tackle and was simple enough to build. Using a wax pen to draw the traces on the board and etching it in the kitchen sink. I drilled all those holes by hand and stuffed it all from parts off the shelf from Radio Shack except the opamps. They had dual opamps but not NE5532s so I got them from Allied or some place like that. The 5532s is what the plan called for and not knowing any different that is what I used. Thing is it worked and it worked good. Placed in the middle of a room with a few mics setup and musicians gathered around, each had their own headphone level controller. MDR V6s were mostly used and the amp had no problem driving them.

Cheers!
 
J

jcx

Member
Joined 2003
Last edited:
R

RoadToNever

Member
Joined 2011
Thanks, guys. It all leads me back to the Jaycar kit due to the low output impedance and ready-made board. BTW the schematic I posted in post #14 was incorrect, this should be the right one:
studio_series_stereo_headphone_amplifier_circuit_diagram.jpg
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom