Replace TL072 on my ES9023 DAC (help)

Blixa

Member
2015-10-07 11:24 am
Hello everybody!
I would like (or better, i've tried with no results) to upgrade the 4 opamps on my es9023, currently there are the cheapest TL072.
I've tried to put in four LME4972 and also the OP275, but in both configurations they generated distortion.
To remedy at this i must take down the volume of dac, about -30db than the TL072..
I've little technical knowledge but the datasheets of all this opamps seems compatible with each other, have you any suggestion about causes?

P.s. i've already tried to solder 0.1uf capacitors from opamps power input to gnd to prevent autoscillations without results.

Many thanks!!
 
Opamp rolling rarely actually improves anything if the original was good to begin with. First of all, you're replacing an opamp having JFET inputs with one having BJT inputs, so without modifying the circuit to accommodate that change, you have caused the first issue; miss-matched input biasing requirements. Next we have the issue of replacing a slower opamp with one that is much faster, and that's a can of worms ready to blow-up in your face (not a pretty sight! :) ) So again, circuit revisions are required to achieve proper operation. Next there's supply bypassing which you tried to address by throwing some random caps at to see if it would help, it didn't as you found.
My advice is that if you don't understand the circuit as well as the original designer, it's better to leave a working unit as is until you do. Trying to "improve" it under those circumstances is equally likely to make things worse as make them better.

Mike
 

Blixa

Member
2015-10-07 11:24 am
Thanks guys for your support, in first..
I've made the typical newbee mistake, i should have find more info about opamp rolling, but i searched on web many info about the compatibility and i found some people that replace TL072 with OP275 with success.
Also input technology seems compatible or hybrid (BFET).
The dac in tis link is exactly what i have and the 4 opamps seems LME4972, furthermore he used without any problem (apparently) hdam modules:

es sabre 9018 - [GE] DAC Breeze Audio Sabre 9018 a 100€+s.s.
 

Eldam

Banned
2012-09-13 12:25 am
France
ES9023 dac chip can be also working without further output stages....

Try to look for Joachim Gerard buffer designed for this chip !

I believe JLSounds lab is selling a populated pcb for it !

Add a nice supply à la Mravica member (TSA7 regulator pcb) and you should get a better result than just swapping by luck the oaps imho !
 

Blixa

Member
2015-10-07 11:24 am
Hello guys, bad news..
past week i tried to check the opamps with dac in function and 2 of these were too hot (TL072, the original stock of opamps in this dac); i thought that could be a problem with opamps failure, so i replace all with TLE2072, indicated by TI like the natural upgrade of TL072.
I turned it on dac and in 20" two of four opamps have destroyed themselves, letterally broken in half.. The broken opamps are in the same sockets of the previous TL072 that warming themselves.
I've seen on bottom of pcb and apparently is all ok, no shorts.. Have you any ideas of the cause of this damage?
It could be in relation with my previuos attempts of upgrade?

Thanks to all...
Marco
 

Blixa

Member
2015-10-07 11:24 am
ES9023 dac chip can be also working without further output stages....

Try to look for Joachim Gerard buffer designed for this chip !

I believe JLSounds lab is selling a populated pcb for it !

Add a nice supply à la Mravica member (TSA7 regulator pcb) and you should get a better result than just swapping by luck the oaps imho !

Thanks Eldam, seems very interesting and run also with 9018.. I'll read the thread one of these days.
 

Mooly

Administrator
Paid Member
2007-09-15 8:14 am
Sounds a bit odd. Take the IC's out and check the supply voltages are correct and of the correct polarity on the socket.

Opamps frying are usually down to one of three things,

1/ Fitted the wrong way around.

2/ A supply rail is being fed into one of the other pins.

3/ The opamps either aren't what you thought they were and/or the replacements are fake parts.

With correct supplies they should stand pretty much any abuse including having the output shorted to a rail.
 

Blixa

Member
2015-10-07 11:24 am
Sounds a bit odd. Take the IC's out and check the supply voltages are correct and of the correct polarity on the socket.

Opamps frying are usually down to one of three things,

1/ Fitted the wrong way around.

2/ A supply rail is being fed into one of the other pins.

3/ The opamps either aren't what you thought they were and/or the replacements are fake parts.

With correct supplies they should stand pretty much any abuse including having the output shorted to a rail.

Thanks Mooly, this evening i'll test the voltages.

As far as the different causes:

1) no, i check 5 times every replacement or modify before switch on;

2) not apparently, but i can't guarantee this because i've checked only "at sight".
The bottom of PCB is clean. I can also check the 8pin socket but they are
damaged and i think it's useless..
Maybe can help: the pin that seems most damaged is the 7, output B.

3) I bought the 49720 through a non offiacial way, maybe this can be fake
but not the OP275 and the TLE2072, these came from RS and TME..

I still have a series of TL072.

The strange thing is that (sorry for my english, i'll try to be more clear possible):
-the DAC was ok, i get off the TL072 and put in OP275;
-the sound was distorted and therefore i've immediatly get off the OP275;
-i put in the TL072 but no sound from DAC, i've touched the opamps and 2 were too hot, i switch off.
-i thought that was an issue with the 2 TL072, so i have tried the TLE2072
and after a few seconds two of them are broken in half.. :confused:
 

Blixa

Member
2015-10-07 11:24 am
Often heard at Guitar Amp repair shops all over the World:

1) unhappy customer brings modded amp.

2) comes one week later, tests, and with a smile in his face says:
- "NOW it sounds good, what Mod did you add?"
- "I set it to Factory original spec"


3) applies to tons other Audio products, most probably also to DACs.

Maybe you're right JM, i think so in many things, but i'm not sure that the sets of opamps that i've found in this DAC was the original..
Believe me, i'm not a man that search/try/change/replace everythings in my audio sets :), i've only read some feedback about the TL072 and they seems very very cheap opamp, very simple to upgrading with satisfaction..
If i could come back i wouldn't touch even the screws :D
 

Blixa

Member
2015-10-07 11:24 am
Good news (maybe):
the producer of my pcb has just written to me, this version of DAC has 2 opamp dual and 2 mono;
I check the circuit and the 2 faulty opamps were in the mono sockets, where the DC+ is in the pin 7, the most damaged, i also checked the first set of op and 2 of these are NE5534, mono..
I didn't know that was possible use two different tipology of opamp, i'm a newbee in this.. :(