Done a lot of opamp mods on split supplies, and I always put a .18uf film cap between V+ and V-, not to ground. This is what was recommended to me years ago by a EE buddy, and works great...no problems.
I'm looking for a good op amp
after having read the whole thread, I've seen that the 8610/8620 are really good
but only available on smd
after having read the whole thread, I've seen that the 8610/8620 are really good
but only available on smd
Bricolo said:I'm looking for a good op amp
after having read the whole thread, I've seen that the 8610/8620 are really good but only available on smd
But 0.05" pitch is not so hard to solder by hand. 0.63 mm or less is much harder.... ask the DAC guys.
I agree that the chips you are thinking of seems very interesting but also good pcb layout seems also be very important. Unfortunately I have never come across these chips.
Helix said:
Normally you decouple each rail down to ground, very close to the opamp. => your first suggestion is "normal".
This seems odd, since most opamps are not referenced to ground. In many of the designs I have worked on or built, there isn't a ground trace anywhere near the opamp, so V+ to gnd and V- to gnd isn't possible.
In the long run, I doubt it matters whether the amp is bypassed to gnd or V+ to V-, and long as there is a path to prevent oscillation. The quality of the capacitors is probably of considerably higher importance here than the bypass method used.
In the long run, I doubt it matters whether the amp is bypassed to gnd or V+ to V-, and long as there is a path to prevent oscillation. The quality of the capacitors is probably of considerably higher importance here than the bypass method used.
OPA134
Sorry for the note if u already know this!!
regards, machinow, Bulgaria
OPA134 series opamp is JFET-input type, and will produce greater distortion for unmatched source resistance greater than 2kohms /see datasheet/ If u use it after 100 kohms Volume pot, this will cause about 0.02..0.06% THD at 20kHz, but do u hear that??TJ said:
Sorry for the note if u already know this!!
regards, machinow, Bulgaria
EchoWars said:
Normally you have a load refered to ground. Of course you can put a capacitor between V- and V+ as a first step but if you have a fast opamp, I don't think this is sufficient.
Bricolo said:
I say OPA134, my new favorite for general purpose in audio, very clean electrical performance, not too fast, easy to get working. Lot's of pros and few cons.
Re: OPA134
Most of the time a 10k potentiometer is quite OK, very few signal sources can't deliver signal in 10k.
machinow said:
Most of the time a 10k potentiometer is quite OK, very few signal sources can't deliver signal in 10k.
EchoWars said:
I strongly recommend reading the following application note
about ground references and decoupling of op amps.
http://www.analog.com/UploadedFiles/Application_Notes/135208865AN-202.pdf
The author argues that opamps are always referenced to
ground, through the load, which they are, of course. According
to the author it is very important to decouple one of the rails
to ground, which of them depends on the opamp. He seems
even to claim that it is often not necessary to decouple both
rails. Decoupling V+ to V- only seems not to be a good idea
based on the reasoning in this article, although it can probably
sometimes be useful in addition to decoupling the rails to ground.
And, of course, one must also be careful and do the decoupling
to ground in the right way etc.
IMHO the AD-8610/20 are the smoothest and one of the more revealing op amps available. THe AD-843 is what i would consider overall, Slightly better by having alot more Punch and Dynamic range throught the Audio range and Slightly more Detailed But this detail can be a curse on bad source components or Recordings. Not that the 8610 lacks detail it is just not as in your face as the 843. the Deep Bass of the 843 being more Dynamic than the 8610 allows the same emotional involvement at lower Listening levels. this quality is the most noticable difference between the AD-8610 & the AD-843.
IMHO the AD-8610 & the AD-843 are sonicaly better than my next favoite Op Amp the OPA-627 & OPA-637 for gains greater than 10 the data sheet says 5 but i like to be on the safe side.
Other interesting Op Amp's But on the warm side are the AD-845. this is an ideal Musical opamp to use unbuffered because of the High output stage Bias. Lots of Punch but real cleen borderline Dark sounding but great for Bright sources. The Intersil HA-5160 is similar sounding to the AD-845 when Lightly Loaded > than 10K, However the Great feature of the 5160 is having a Compensation pin Located on the Same internal node as the AD-744 and AD-829 allowing direct drive of an External output stage like a Buffer.
Often overlooked but great sounding is the Op Amp Buffer Combo is the LT-1122 and the LT-1010 Buffer. Warm but not dark sounding the sonics of the LT-1122 by itself is similar tho the AD-845 but not as Dynamic. BTY the AD-845 is sonicaly good with the LT-1010. the sound of the LT-1010 buffer are way better than the specs would indicate this is a very Dynamic and articulate Buffer. The Buffer should be operatted High Bias by a 22 ohm Bandwidth resistor If Enough heatsink is available real strong Class A Bias is possible but be carfull I overtaxed a TO-220 LT-1010 @ 100 Ma Bias. Did not realise it was that High untill it was too late. but 50-60 Ma is possible with enought heatsinking.
Hope you can make sence out off theis sweeping general overview.
IMHO the AD-8610 & the AD-843 are sonicaly better than my next favoite Op Amp the OPA-627 & OPA-637 for gains greater than 10 the data sheet says 5 but i like to be on the safe side.
Other interesting Op Amp's But on the warm side are the AD-845. this is an ideal Musical opamp to use unbuffered because of the High output stage Bias. Lots of Punch but real cleen borderline Dark sounding but great for Bright sources. The Intersil HA-5160 is similar sounding to the AD-845 when Lightly Loaded > than 10K, However the Great feature of the 5160 is having a Compensation pin Located on the Same internal node as the AD-744 and AD-829 allowing direct drive of an External output stage like a Buffer.
Often overlooked but great sounding is the Op Amp Buffer Combo is the LT-1122 and the LT-1010 Buffer. Warm but not dark sounding the sonics of the LT-1122 by itself is similar tho the AD-845 but not as Dynamic. BTY the AD-845 is sonicaly good with the LT-1010. the sound of the LT-1010 buffer are way better than the specs would indicate this is a very Dynamic and articulate Buffer. The Buffer should be operatted High Bias by a 22 ohm Bandwidth resistor If Enough heatsink is available real strong Class A Bias is possible but be carfull I overtaxed a TO-220 LT-1010 @ 100 Ma Bias. Did not realise it was that High untill it was too late. but 50-60 Ma is possible with enought heatsinking.
Hope you can make sence out off theis sweeping general overview.
If you use the AD845AQ or BQ cerdip (ceramic) packages, you'll note they sound less dark and thick, and take on a much cleaner character. I've found this for most chips that have cerdip packages available.
Even the AD711 benefits from the ceramic package. In fact, I have some steel enclosed versions of the this opamp that are very very good. Unfortunately, they are no longer available.
If there is the availability of different package materials, try them.
Even the AD711 benefits from the ceramic package. In fact, I have some steel enclosed versions of the this opamp that are very very good. Unfortunately, they are no longer available.
If there is the availability of different package materials, try them.
LT1010 - A great TO220 Output - For Small Amplifiers with real Drive-Potential
So is formula - I=1.10/Ohms - ????
22Ohms x 0.050Ampere= 1.10
when we set the bias for the LT1010
-----------------------------------
Better to be clear about it.
We can not take for guaranted everybody is going to download the Datasheet, just to get the more accurate formula.
------------------------------------------------------
But a TO220 Buffer like LT-1010 with enormous specifications
is certainly an overlooked alternative.
A perfect combo for any OP-amplifier
- to give a lot of CURRENT output
-------------------------------------------------------
😉 Thanks, ppl 😉 for a very good advice
/halo LT1010 - A great TO220 Output - For Small Amplifiers with real Drive-Potential
😎 LT1010 - A great TO220 Output - For Small Amplifiers with real Drive-Potential 😎ppl said:
So is formula - I=1.10/Ohms - ????
22Ohms x 0.050Ampere= 1.10
when we set the bias for the LT1010
-----------------------------------
Better to be clear about it.
We can not take for guaranted everybody is going to download the Datasheet, just to get the more accurate formula.
------------------------------------------------------
But a TO220 Buffer like LT-1010 with enormous specifications
is certainly an overlooked alternative.
A perfect combo for any OP-amplifier
- to give a lot of CURRENT output
-------------------------------------------------------
😉 Thanks, ppl 😉 for a very good advice
/halo LT1010 - A great TO220 Output - For Small Amplifiers with real Drive-Potential
electrode10101> I also thought that Op Amps in the Metal can and the Cer Dip Packages sounded slightly Better than the Plastic versions. why this is so i do not Know. Maybe Capacitence of the Different Packages or somthing.
So what is the formulappl said:
for setting the bias current in LT1010
Maybe you just did not see my question?
ppl
/halo - is waiting for answer - so are others, maybe
Decoupling op-amps
There are circumstances where decoupling to ground in audio makes things sound worse.
In my headphone amp, despite true star-earth / star-supply wiring, decoupling the op-amp pins to ground injects noise currents from the PSU, that is clearly audible as a sonic degradation.
Decoupling between -V and +V rails cured this and it sounds much better as a result of the reduced current flow within the audio reference 0V, despite there being almost no shared current path.
Andy.
There are circumstances where decoupling to ground in audio makes things sound worse.
In my headphone amp, despite true star-earth / star-supply wiring, decoupling the op-amp pins to ground injects noise currents from the PSU, that is clearly audible as a sonic degradation.
Decoupling between -V and +V rails cured this and it sounds much better as a result of the reduced current flow within the audio reference 0V, despite there being almost no shared current path.
Andy.
Nice link. It still doesn't help when there is no ground within the vicinity of the opamp.Christer said:
I may modify my own practices according to the article, but when a ground is unavailable I still must decouple V+ to V-. Interesting that in the many circuits I have built and repaired in the past that all have decoupling from V+ to V- no problems have been noted. Still, he makes good arguments.
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