Building the ArnCMoy

[dogears]

please post parts and building inquiries here

[arnoldc]

What you will need, assuming you will build your own from scratch.

1 x OPA2134 (dual opamp) or equivalent

2 x 100K resistor
3 x 10K resistor
2 x 1K resistor
2 x 4K7 resistor

* all resistors 1/8 or 1/4 watt (pick your poison - metal film, carbon, etc. with the exception of both 4K7 and one 10K, everything is in the signal path)

2 x 220uF 50V electrolytic capacitor
2 x 0.1uF 50V film capacitor (pick your poison here as this is in the signal path)

1 x 10K volume potentiometer (mini type, PCB mount)
2 x 3.5mm stereo jack (female)
1 x low-current mini LED (i prefer blue)
1 x SPST mini toggle switch
1 x 8-pin IC socket
1 x 9V battery holder
1 x 9V battery

You will also need a PCB. Those used for breadboarding is perfect.

[corrsty]

gagawan daw ako ni master arnold.........hwehwehwehwe.....

i'd like to hear the ArnCMoy with your SR80 or Senn cans.

[arnoldc]

sinabi ko ba yun?

o sige swap with Denon DL103R?

[dogears]

Me binubuo din akong headphone amp/line buffer.... isabak natin sa barilan pag natapos ko

[arnoldc]

e gawa ka ng sarili mong thread with all the specs and details

[dogears]

hintayin ko munang mabuo kung worthy
musta yung cmoy as line buffer?

[arnoldc]

will make the adaptors when i'm feeling good. sakit ng ulo ko simula kagabi. alang inspiration gumawa.

[dogears]

Using the battery for the CMOY is a great help on the sound. I've compared a laptop AC adapter versus 2x9V battery with my Headsave Classic and the difference across the frequency range specially on the bass is huge!

So guys, start purchasing/getting your rechargeable 9V batts

[aye]

my 2c

if you could check if your source has no dc offset you could do away with the input coupling capacitor. provided that the opamp you will use is fet input not bipolar input.

based on texas instrument app notes, 0.1uf ceramic cap on both opamp supply pins also helps.

im not sure if anyone have tried biasing a cmoy into class a?

[arnoldc]

jaiyneg, maybe for another project. it can be difficut to pre-determine the different source's charateristics. dapat idiot proof. bipolars mas maarte, might need perfectly balanced dc currents and will require more parts.

i'm an advocate of KISS

[arnoldc]

here's the first one... pero wala pa yung stereo na volume control.



since the power switch is not mini type, you have to hold it on it's body while flicking the switch.

[Gino]

I have a cmoy with OPA2132PA in it. When I plugged in an OPA2604PA on it, I got low volume and basag sound. The 2604PA is dual right? I want to try my dual OPA627Au (two OPA627AU on a Browndog adaptor) but fear same thing will happen. Are these opamps not interchangable in my cmoy?

My parts:

PANASONIC 470uF PS CAPS
YAGEO 1% METAL FILM RESISTORS
OPA 2132 OP AMP
RED LED
PANASONIC EVJ SERIES 10K POTENTIOMETER
SWITCHCRAFT MINI JACKS
NKK MINI TOGGLE SWITCH
9V BATTERY POWER

[bruno]

The 2604's minimum input voltage is +/- 4.5 volts while the 2132 can go as low as +/- 2.5v.

The 2604 might be gasping for power kaya it went into distortion.

The 627 also requires a minimum of +/- 4.5v.

Or it could also be that the 2604 is going into oscillation. The 2604's GBW is 20 MHz as compared to the 2132's GBW of 8 MHz makes it more susceptible to oscillation. Solution for this is bypass caps across the power supplies + and - to the ground placed as closely to the op-amp.