Was the default opamp for DC servos once especially in Elektor designs. Elektor choose them for low offset low drift AFAIK.
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👍 Maybe it's UK/Europe/USA thing in that it seemed always to be TL0 chips we saw here rather than LF ones. At least for diy.
Just looked at CPC for curiosity (its the sort of public outlet of Farnell and does all sorts of stuff from components to gardening...) TL071 is £0.76 and LF411 is £2.38 for one off's. Both genuine TI.
That sounds expensive actually although its been a while since I've bought any opamps.
That sounds expensive actually although its been a while since I've bought any opamps.
Guys, it works!
I have another question, if i push EQ defeat, does the signal still through QE01 (IC 4558)? Is that the QE01 the important things that affect overall sonic and signature of the preamp?
If i replaced that QE01 does the signature will change?
While testing and listening to them, unlucky something wrong in Sansui AU-517 , left channel is like missing, then like a noice sometimes comes in, and out, s bit steady around 3 mnts and full steady in around 5-8 mnts. I better make a different thread about it.
I have another question, if i push EQ defeat, does the signal still through QE01 (IC 4558)? Is that the QE01 the important things that affect overall sonic and signature of the preamp?
If i replaced that QE01 does the signature will change?
While testing and listening to them, unlucky something wrong in Sansui AU-517 , left channel is like missing, then like a noice sometimes comes in, and out, s bit steady around 3 mnts and full steady in around 5-8 mnts. I better make a different thread about it.
Noted, will try them when i go shopping. are they just replace? no need to adjust resistor or e-cap around them?
Hi I did not endorse opamp rolling but suggested to replace the plain mediocre NJM4558 for "something decent". In post #11 I even specified
NE5532, JFET OP249 and NJM4580 which are all decent, all practically guaranteed to perform/sound better plus they are all three forgiving with regards to PCB layout and decoupling. So with the goal to have the OP having a stable and well performing device with good results and not an oscillator or RF transmitter. You suggested to replace the DC servo opamp of the non used power amp 😀
It seems quite good information really. I wish I would have had such detailed instructions when I started with this hobby.
NE5532, JFET OP249 and NJM4580 which are all decent, all practically guaranteed to perform/sound better plus they are all three forgiving with regards to PCB layout and decoupling. So with the goal to have the OP having a stable and well performing device with good results and not an oscillator or RF transmitter. You suggested to replace the DC servo opamp of the non used power amp 😀
It seems quite good information really. I wish I would have had such detailed instructions when I started with this hobby.
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Correct. Anyway, there are just three of these subpar devices. We yet had the concluding discussion on the servo amp one. Both the other ones are parts in a compartment that audiophiles don't really need. So, why bother?
Best regards!
Best regards!
Are you guys debating? Please no...
Both of you guys helping me alot. Ill take all your input.
@jean-paul i heave aidea to play around with the ic you mention, and also found in googling. After i get what i like, then i put the IC without socket permanently.
@Kay Pirinha also give me an idea to play around of the amplifier later as an power amplifier like (MAIN IN).
Here is the list of what i plan to buy:
Both of you guys helping me alot. Ill take all your input.
@jean-paul i heave aidea to play around with the ic you mention, and also found in googling. After i get what i like, then i put the IC without socket permanently.
@Kay Pirinha also give me an idea to play around of the amplifier later as an power amplifier like (MAIN IN).
Here is the list of what i plan to buy:
- NJM4580
- NE5532
- TL072
- OPA2134
NJM4580 is OK, NE5532 is one of the best measuring opamps and OK (probably best choice), OPA2134 is also usable and nice. TL072 is simply terrible and maybe even worse than NJM4558. Never use TL072 or TL082 in the signal path in audio! Long ago I worked with a very intelligent and gifted designer that designed and sold audio kits and he chose TL071 for an amplifier. The single largest improvement was to NOT use that TL071 😀 All people make mistakes.
Yes, using a socket for testing is a good idea...when the PCB tracks don't peel off because of age and resoldering one time to much. That is why I recommend to use no sockets. If you ask if the ICs can just be plugged in I advise not to do too much and just choose an opamp and make sure you solder it right in so with pin 1 at the right place 🙂 You can not go wrong with the suggested types and all are better than NJM4558. Direct improvement normally. Contrary to popular belief there is always one NJM4558 opamp (QE01) in the signal path regardless of the "EQ Defeat" position!
No debate but he wants to correct me while no error was made.
Yes, using a socket for testing is a good idea...when the PCB tracks don't peel off because of age and resoldering one time to much. That is why I recommend to use no sockets. If you ask if the ICs can just be plugged in I advise not to do too much and just choose an opamp and make sure you solder it right in so with pin 1 at the right place 🙂 You can not go wrong with the suggested types and all are better than NJM4558. Direct improvement normally. Contrary to popular belief there is always one NJM4558 opamp (QE01) in the signal path regardless of the "EQ Defeat" position!
No debate but he wants to correct me while no error was made.
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Yes! Is there enough space at the device's back plate? Then I'd add two pairs of RCA terminals that I'd call Pre Out and Power Amp In, resp., and connect them according to your idea in your 1st posting. Something like that could be found in very much integrated amplifiers of that era.
And also yes, you can replace the servo dual opamp by a TL072 and the ones in the EQ section by two NE5532's, if you like. But remember that you can disable the EQ completely just by throwing a switch.
Best regards!
And also yes, you can replace the servo dual opamp by a TL072 and the ones in the EQ section by two NE5532's, if you like. But remember that you can disable the EQ completely just by throwing a switch.
Best regards!
Sockets are fine to try out different opamps. If you are not used to using them then be very careful removing the IC's as it is easy to get them fully embedded in your finger 😀
Lever them out a mm at a time from each end until free.
Yes deleted my post though. Bad feeling!
Today is resting day but we are renovating old electrical rolling shutters with broken plastic slats, adding isolation, replacing @&£%# domotica (who wants to depend on Internet for everything in a home?) for reliable switches etc.
I thought it to be a good idea to throw a broken 2.5 meter long slat through an open window. Like a spear, in the garden.
Zip, during its take off it touched my hand and beautyfully cut it like a knife. Old plastic can be quite sharp.
Today is resting day but we are renovating old electrical rolling shutters with broken plastic slats, adding isolation, replacing @&£%# domotica (who wants to depend on Internet for everything in a home?) for reliable switches etc.
I thought it to be a good idea to throw a broken 2.5 meter long slat through an open window. Like a spear, in the garden.
Zip, during its take off it touched my hand and beautyfully cut it like a knife. Old plastic can be quite sharp.
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