op amp continued
I have found that the higher the slew rate of the op amp was high, at more dynamic listening decreases.
Treble quality MC1458 (dual 741 !) are not very good but the dynamics and focus instruments are great! Very close to the sound of tubes, very life and presence.
Treble and harmonics are much more respected with OPA 2604 or LM4562 for example but the dynamics is very flat, the sound is lifeless, it is not very musical, i can't listen as is !.
Someone has an idea about this? I do not understand this phenomenon. I think the decoupling capacitors which certainly have a greater effect on an fast op amp while the MC1458 is too slow to be affected by a poor decoupling. I have not made these changes.
I have found that the higher the slew rate of the op amp was high, at more dynamic listening decreases.
Treble quality MC1458 (dual 741 !) are not very good but the dynamics and focus instruments are great! Very close to the sound of tubes, very life and presence.
Treble and harmonics are much more respected with OPA 2604 or LM4562 for example but the dynamics is very flat, the sound is lifeless, it is not very musical, i can't listen as is !.
Someone has an idea about this? I do not understand this phenomenon. I think the decoupling capacitors which certainly have a greater effect on an fast op amp while the MC1458 is too slow to be affected by a poor decoupling. I have not made these changes.
I think there are many reasons...
Firstly you may just like the sound you hear with the 1458, there's no shame in that. Also we don't (I think... haven't read the whole thread) know what your points of reference are, what your system is, what speakers/amp etc you are using.
Drop a 741 (used correctly and within its limitations) into a £€$10,000 system and it isn't quite the doom and gloom that many assume.
Also, are you sure the faster opamps are totally stable,
http://www.diyaudio.com/forums/anal...u-have-checked-see-its-stable-havent-you.html
Firstly you may just like the sound you hear with the 1458, there's no shame in that. Also we don't (I think... haven't read the whole thread) know what your points of reference are, what your system is, what speakers/amp etc you are using.
Drop a 741 (used correctly and within its limitations) into a £€$10,000 system and it isn't quite the doom and gloom that many assume.
Also, are you sure the faster opamps are totally stable,
http://www.diyaudio.com/forums/anal...u-have-checked-see-its-stable-havent-you.html
Hello Mooly, thanks for your answer.
My system is:
AMP : JLH class A 15 Watts diy amp / DIY 300 B 10W amp with Lundahl Output SE 1623
SPEAKERS : KLIPSH RF82 (98 db/1w)- FOSTEX FE103S TQWT
SOURCES (digital out use only): SQUEEZEBOX TOUCH / MARANTZ CD42 MKii
SOURCES ANALOG : LENCO L75 with Denon DL110 cartridge - DIY TUBE SRPP Riaa preamp like Hiraga.
DAC : TNT CONVERTUS 1543 x4 in // with triple psu and more than 100 000 uF filter caps
AK4396 DAC KIT bought on Ebay as is.
The sound of TNT Convertus is very very dynamic in comparison with AK4396.
The dynamic is in comparison when i use a mc1458 but not the sound.
Regards
My system is:
AMP : JLH class A 15 Watts diy amp / DIY 300 B 10W amp with Lundahl Output SE 1623
SPEAKERS : KLIPSH RF82 (98 db/1w)- FOSTEX FE103S TQWT
SOURCES (digital out use only): SQUEEZEBOX TOUCH / MARANTZ CD42 MKii
SOURCES ANALOG : LENCO L75 with Denon DL110 cartridge - DIY TUBE SRPP Riaa preamp like Hiraga.
DAC : TNT CONVERTUS 1543 x4 in // with triple psu and more than 100 000 uF filter caps
AK4396 DAC KIT bought on Ebay as is.
The sound of TNT Convertus is very very dynamic in comparison with AK4396.
The dynamic is in comparison when i use a mc1458 but not the sound.
Regards
Seems like a very decent set up 
and one thats capable of showing the differences in components.
I would perhaps take the Marantz as a kind of reference... and so maybe the sound you experience with this DAC is "how it is".
I would really expect something like the OPA2604's to be better than the 1458 on extended listening so maybe something is going on stability or "compatability" wise.
Don't know what to suggest... it might just be the way it is for this DAC.
and one thats capable of showing the differences in components.I would perhaps take the Marantz as a kind of reference... and so maybe the sound you experience with this DAC is "how it is".
I would really expect something like the OPA2604's to be better than the 1458 on extended listening so maybe something is going on stability or "compatability" wise.
Don't know what to suggest... it might just be the way it is for this DAC.
I have tested the OPA2604 and i don't like it. Flat dynamics and too much highs. I prefer the 2134, the sound is more "live" and warm but dynamics are too flat too. I have tested the OPA2604 and i don't like it. Flat dynamics and too much highs. I prefer the 2134, the sound is more "live" and warm, good focus too, but dynamics are too flat . Original 5532 is very bad , i prefer a TL072 instead !
I'll test a good decoupling for the opamp, I'll see if that changes anything.!
I'll test a good decoupling for the opamp, I'll see if that changes anything.!
Best advice I can give is to trust what you hear
Listen for an extended time, perhaps a few days or more to each. And go with what you like. At the very least you need to scope the opamp and check stability. You could also try a small (in the 5.6 to 22pf range) cap across each opamp from output to inverting input. So thats two caps per opamp.
Listen for an extended time, perhaps a few days or more to each. And go with what you like. At the very least you need to scope the opamp and check stability. You could also try a small (in the 5.6 to 22pf range) cap across each opamp from output to inverting input. So thats two caps per opamp.
The cap would tame any tendancy to oscillate. You might also be interested in this if you like experimenting,
http://www.diyaudio.com/forums/analog-line-level/196461-different-opamp-compensation-technique.html
http://www.diyaudio.com/forums/analog-line-level/196461-different-opamp-compensation-technique.html
Ok but there's already a 1 nf cap between output and inverting input on the op amp. I don't think there's an oscillation but a design problem . Have a look on the shema: HobbyAudio.Com: CHEAP DAC KIT MINI2496 AK4396
Several mods suggested in my BOM affect dinamic... LPF caps, regulators and opamp.
You may want to try OPA211 or OPA827 but first replace LPF caps.
The difference in the dynamic listening is such that it is not just a matter of taste. I do not understand. I may be trying an output transformer or srpp tube output. I do not like the op amp, there is no one in the signal path in my system except this one for the first time ! But, I'd like to understand. it annoys me.
Last edited:
Hi!Several mods suggested in my BOM affect dinamic... LPF caps, regulators and opamp.
You may want to try OPA211 or OPA827 but first replace LPF caps.
What kind of capacitors do you use for lpf section?
Thank you. Good work !!
You use fkp. I have some styroflex in stock, i think it's better. I use styroflex in lpf section on my riaa preamp and these gave me the best result.
My dac is design for the ak4393 but there's a ak4396 on it! The lpf component values are those of the 4393 lpf section.
You use fkp. I have some styroflex in stock, i think it's better. I use styroflex in lpf section on my riaa preamp and these gave me the best result.
My dac is design for the ak4393 but there's a ak4396 on it! The lpf component values are those of the 4393 lpf section.
Well, after a succesfull MyRef Fremen project i'm coming along to you again with this project wich seems to be very successfull.
As i have no DAC now (my previous one has died and another project failed) I have ordered the bare board and the upgrade BOM from Distrelec.
@Dario: if i remember well you choose to use +/- 15V for opamp even in the upgrade BOM you put the 12 volt version?
I have ordered 15v version as i noticed some opamp working well closer to maximum voltage (LME49820 for example).
Greetings,
Adrian
As i have no DAC now (my previous one has died and another project failed) I have ordered the bare board and the upgrade BOM from Distrelec.
@Dario: if i remember well you choose to use +/- 15V for opamp even in the upgrade BOM you put the 12 volt version?
I have ordered 15v version as i noticed some opamp working well closer to maximum voltage (LME49820 for example).
Greetings,
Adrian
Hi Adrian,
Upgrade BOM?
With a bare board you should order a full BOM...
Yes, I'm using 15V regulators.
Upgrade BOM?
With a bare board you should order a full BOM...
Yes, I'm using 15V regulators.
Hi, I have just built this and am blow away. This is playing from my SB Touch via DAC to Amp. I used mostly the standard kit from China but replaced 5532 to 4152, capacitors to more standard Nichicon/Elma and the regulators as suggested by Dario.
I think originally there was some harshness/edginess which is now replaced by a smooth sound. Merry Christmas..
I think originally there was some harshness/edginess which is now replaced by a smooth sound. Merry Christmas..