Calling all modded EMU0404 and Aego2 users.

[katopunk 0]

Hie all.

 

I'm not sure if I've posted in the right subforum or not. Seems like I couldn't find any dedicated EMU0404 thread around. I have a question for u guys. Basically it's about the dangerous dc offset value. General question, does most marketed speaker sets amp have output coupling caps for eliminate the dc offset?

 

I'm planning to mod my EMU0404 card. The early stage I'll be removing the coupling caps and the buffer opamps. Then I'll replace the output opamp with OPA2227. Now the thing I'm worried about is the dc offset value that could fry my Aego2. Any forummer with a modded EMU0404 and Aego2? Please advice. Thanks in advance.

 

Merci,

katopunk

[squalle 0]

wat about, just mod it, then measure the DC

 

if let's say it puts out something very high (in terms of volt already, mV range dun need to bother)

then put some film caps to block DC. you dont need high capacitance as your active (i assume) AEgo2 should have rather high input impedance.

 

 

[huangyong 0]

most active speakers should have coupling caps, tt's my experience, could have exception. good luck.

[katopunk 0]

huangyong. thanks for the input. u said most. but i'm still not that convince yet.

Aego2 + modded EMU0404, anyone?

[huangyong 0]

open the speaker and see, or u should just measure the input impedance

[katopunk 0]

wat about, just mod it, then measure the DC

 

if let's say it puts out something very high (in terms of volt already, mV range dun need to bother)

then put some film caps to block DC. you dont need high capacitance as your active (i assume) AEgo2 should have rather high input impedance.

Errmm. actually i'm a electronic noob. Modding my emu0404 is my 1st step.

Does the high input impedance have anything related to the dc offset?

 

huangyong,

you said i should measure the speaker input impedance. i'm kinda

can you further advice?

[siriuz 0]

don't fry your card. good luck

[katopunk 0]

don't fry your card. good luck

i'm not afraid of frying my card resulting from bad soldering or whatsoever. what i'm worrying about is frying my speaker sets.

 

edited:typo

Edited April 18, 2006 by katopunk

[siriuz 0]

if i were you i'd really be more worried about frying the card than frying the speakers

'cause as squalle mentioned, dc offset can be tested for with a multimeter

[squalle 0]

katopunk, you not only need luck, but a proper set of tools

 

correct tooling will help you by a lot

 

have you got any rig to clamp the card

then, magnifying glass if necessary

iron with correct size

ADD: a good multimeter too

ADD: a good pair of tweezers, one size or a few when necessary

and also, how fast and how steady ur hands are?

 

normally, those cards are quite packed. you might be able to desolder the caps properly, but might destroy other parts of the card if you accidentally touch here n there

 

but then, who am I to teach you

just another noob

Edited April 18, 2006 by squalle

[katopunk 0]

ok.. job done.

DC offset measured is 225mV and 320mV. i consulted someone, and he said it's safe for a speaker sets to have less than 1V.

and for headphones, less than 300mV. THanks all.

[huangyong 0]

it's still quite high dude.

[squalle 0]

try measure at the port to speakers

and report back again here

 

btw, congratz to have done it safely

[katopunk 0]

try measure at the port to speakers

and report back again here

 

btw, congratz to have done it safely

the DC offset i reported in my previous post was from the speaker sats RCA port. meaning the card is connected to the speaker.

 

edited:typo

Edited April 20, 2006 by katopunk

[squalle 0]

oh

 

good then

 

200mV is OK

 

the 200mV might be due to the op-amp at EMU side

or might be due to the AEgo active amplification module

 

can you please measure the EMU output? wat's the DC offset there

I expect some amount there as you're using 2227