Heres the results:
Opamp changed = DC dropped from 88ish to 79ish (was used opamp maybe TI)
Resistor measured 6.67M (was used resistor) DC dropped from 79 to 6mv
I didnt do it personally and the parts were used. The opamp was pulled from a working machine and also the resistor.
The sound became much louder in opamp and resistor change. The treble brighter but DC droped to 6.6mv on output.
I was just informed the DC measured -90MV on PIN 2 and 3 of opamp. Although it cured the intial issue it has rasied another! Louder and brighter. Apparently a quarter more in volume when you turn the dial. Any advice appreciated.
Opamp changed = DC dropped from 88ish to 79ish (was used opamp maybe TI)
Resistor measured 6.67M (was used resistor) DC dropped from 79 to 6mv
I didnt do it personally and the parts were used. The opamp was pulled from a working machine and also the resistor.
The sound became much louder in opamp and resistor change. The treble brighter but DC droped to 6.6mv on output.
I was just informed the DC measured -90MV on PIN 2 and 3 of opamp. Although it cured the intial issue it has rasied another! Louder and brighter. Apparently a quarter more in volume when you turn the dial. Any advice appreciated.
Were other resistors changed at the same time? You could measure and report gain of each channel and frequency response. If the changes are real, not subjective, there has to be a reason. And I believe it has nothing to due to with offset voltage.
The volume was significantly louder with resistor. I heard it myself through the phone, maybe the brightness came from it just being louder. Ok the brighness might be questionable but the volume has certainly increased. Like almost doubled at same volume level.
I can't measure as I have my scope here and only a Multimeter with the amp location.
I can't measure as I have my scope here and only a Multimeter with the amp location.
If you disconnected the 6.67M resistor, the amp would be back to original, aside from a different opamp of the same type--- right? Try that simple change and see what happens!
Ok, let's clear some things up. Is the amplifier with you or not ? You can't judge the sound over the phone for Pete's sake man !
/me joking 😉
Ok its late here (2am) after a 25 min chat it turns out its the opamp that caused the massive increase in volume lol
Can't believe it, can another brand opamp change the volume that much? its almost doubled they are both NE5534!
Ive just been told its got a big S on the opamp. Can get confirmation/picture tomorrow perhaps.
I'll check out the quality myself tomorrow but with resistor removed its still loud!
Can't believe it, can another brand opamp change the volume that much? its almost doubled they are both NE5534!
Ive just been told its got a big S on the opamp. Can get confirmation/picture tomorrow perhaps.
I'll check out the quality myself tomorrow but with resistor removed its still loud!
The amplifier is not with me. I'm remote supporting a friend.
Original opamp is JRC5534DD
replacement Signetics NE5534
Old sounds dull in comparison
new sounds louder and brighter in comparion.
Have to confirm but the difference is very very obvious
Original opamp is JRC5534DD
replacement Signetics NE5534
Old sounds dull in comparison
new sounds louder and brighter in comparion.
Have to confirm but the difference is very very obvious
hahahaha your a genius it fixed the issue. I'll have to check and confirm whats going on myself, its seems I'm the elected expert lol
Now I guess the question is which opamp is better technically because sound wise something else is going on here!!
Both channels sounded really really good. I heard it as stock in person. Then opamp change and massive increase in volume and what appears to be brighter or clearer treble
If there's an easily audible difference, one of them must be defective.
But try swapping a couple more times, to be sure it's not something else.
I'm very intrigued so I'll be demanding answers tomorrow! I will report my findings and thanks for all the input! But one simply must sleep now lol
That replacement required PCB removal and disconnection of the source. I bet the amp potentiometer position was not the same and/or the source volume was different. Was the same soundtrack played back?
The bottom line is the two ICs should make 0 difference in volume.
I also think that installing an IC socket would be a good idea, albeit some additional track lengths that are going to have a detrimental effect on that DC offset. I suggest you try a very low input bias current JFET OPAmps as well. I suggested one of those earlier.
Also, make sure the solder flux residue is fully removed.
The bottom line is the two ICs should make 0 difference in volume.
I also think that installing an IC socket would be a good idea, albeit some additional track lengths that are going to have a detrimental effect on that DC offset. I suggest you try a very low input bias current JFET OPAmps as well. I suggested one of those earlier.
Also, make sure the solder flux residue is fully removed.