[docentore]

AD8397 might worth a try, why not...just take care of the DYI dual-to-single adapter. I did such DIY adapter myself last year: https://www.head-fi.org/threads/new...mp-rollers-dream.860882/page-17#post-14034674, but only half of the opamp is working, of course.

Thanks. I was thinking of either doing it on 3 different ways:
1. same as you - 2xAD8397 used
2. with "unused" amp terminated - http://www.ti.com/lit/an/sboa204a/sboa204a.pdf - 2xAD8397 used
3. creating DIY adapter dual2single - 1xAD8397 used

 

[Spektykles]

Interesting to know that my "fake" AD797SQ is now behaving like genuine one, atleast in thermal perspective. It heats up very fast like a true AD797 (i guess oscillating), my genuine ANZ also heat up the same, but the SQ has more gain and sounds very similar to 5532. Took a blind test with my AD797ANZ and LME49990 (similar to 797) and i can pick it SQ out with just one ear. Anyone know what ceramic opamp is unstable and oscillating like hell like AD797? I think the Chinese tried to mimic it.

 

[carlmart]

But why don't you try to stabilize it?

Wouldn't a bypass cap between the power pins and two more bypass caps to ground, very close to V+ and V- pins improve that?

There must be recipes to google for with people who solved the AD797 instability issues.

 

[Ivan TT]

I had massive issues with AD797 (B grade, genuine), overheating, sweeping noises, random RFI. Tried every suggestion from the datasheet and all the forums to no avail, solved it eventually by adding RC filter at about 450kHz (or higher sorry don’t remember exact values) to the output. Dead silent, cool and sounds awesome as it should!

 

[Spektykles]

But why don't you try to stabilize it?

Wouldn't a bypass cap between the power pins and two more bypass caps to ground, very close to V+ and V- pins improve that?

There must be recipes to google for with people who solved the AD797 instability issues.

My amp using single dual opamp design and the ground point provided on PCB way too far from the opamp itself so its hard to me for some proper bypass. Anyway i will try to improvise.

 

[scruffy1]

Thanks for suggesion with the SS opamp, I'll try that. Also I'm considering converting the AD8397 dual channel to single channel.

fwiw i have tried the burson v5i and then the v5 in my xonar hdav in the primary slot, and the bursons are both an upgrade on the dual opa627 i had substituted fom the default opamp

and the v5 is transparently better than the v5i - there's also 2 flavours of v6 (classic and vivid); the good news being that due to the new releases the v5 versions have dropped in price, and can be had cheaper than before at burson's site, or on occasion via massdrop, where i picked up the v5 very recently


obviously you have to test them in your own hardware, but both the burson offerings i have bought have been a very worthwhile upgrade

ooee ! not again !
https://www.massdrop.com/buy/burson-audio-v6-classic-op-amps

 

[FritzS]

I had massive issues with AD797 (B grade, genuine), overheating, sweeping noises, random RFI. Tried every suggestion from the datasheet and all the forums to no avail, solved it eventually by adding RC filter at about 450kHz (or higher sorry don’t remember exact values) to the output. Dead silent, cool and sounds awesome as it should!

Have you implement the recommend caps?
CL (in NFB path); Fig. 45, 46; Table 8; the bypass caps V+ (pin 7) V- (pin 4).
https://www.analog.com/media/en/technical-documentation/data-sheets/AD797.pdf

 

[Ivan TT]

Have you implement the recommend caps?
CL (in NFB path); Fig. 45, 46; Table 8; the bypass caps V+ (pin 7) V- (pin 4).
https://www.analog.com/media/en/technical-documentation/data-sheets/AD797.pdf

Tried every suggestion from the datasheet.
Well, only could source 49pF COG caps (not 50pF) and to be honest the circuit had a digital board right above AD797B, and it's not RFI/EMI hardened.
Also it was configured G=1, which did not help with stability.
But the solution above works perfect, listening to music as I type, AD797B is the best opamp ever.
PS: I actually believe Fig. 45, 46; Table 8 suggestions INCREASE susceptibility to oscillation as they effectively decompensate AD797

 

[raoultrifan]

@Ivan TT what was the solution that worked out for you, please? The NFB caps or the bypass caps or increasing the gain?

 

[Ivan TT]

@Ivan TT what was the solution that worked out for you, please? The NFB caps or the bypass caps or increasing the gain?

None of the above.
RC LPF filter on the output, cutoff frequency around 500kHz, ideally using film caps.

 

[docentore]

AD8397 might worth a try, why not...just take care of the DYI dual-to-single adapter. I did such DIY adapter myself last year: https://www.head-fi.org/threads/new...mp-rollers-dream.860882/page-17#post-14034674, but only half of the opamp is working, of course.

Unfortunately the opamp is oscilating (I think), heats up very quickly and stays hot. I've tried adding 0.1uF or 10uF cap (different sources different recs) to power pins but still heats up.

 

[FritzS]

Something else must have gone wrong. In my DIY headphone amplifier the developers had originally used the LM6171. The LM6171 behaves like a "diva" when it comes to oscillation inclination.
Between the output of the OPA and the driver stage there is a ferrite bead. This prevents the LM6171 from oscillating. This is also true for many other OPAs.
I've tried a lot of OPAs, no oscillation has occurred. AD797 was the best till today!

Translated with www.DeepL.com/Translator

 

[FritzS]

Tried every suggestion from the datasheet.
Well, only could source 49pF COG caps (not 50pF) and to be honest the circuit had a digital board right above AD797B, and it's not RFI/EMI hardened.
Also it was configured G=1, which did not help with stability.
But the solution above works perfect, listening to music as I type, AD797B is the best opamp ever.
PS: I actually believe Fig. 45, 46; Table 8 suggestions INCREASE susceptibility to oscillation as they effectively decompensate AD797

If gain 1 or -1 please look at page 13, 14, 15 too.

 

[nesty]

Here is my AD797SQ received a few days ago. Can anybody lookup and find a pic of the real one and compare?
I put them into pure acetone for about 5hrs. No dynasolve or x acto knife for some deep scratch test, although i will get one.

@Spektykles , you have a genuine AD797SQ you see they have a plant in the Philippines. For that reason it's laser printed underneath. That ceramic package is for high temp environment.

 

[Spektykles]

@Spektykles , you have a genuine AD797SQ you see they have a plant in the Philippines. For that reason it's laser printed underneath. That ceramic package is for high temp environment.

But why they are so different for me on SQ? Totally different from the ANZ. Also the fact AD made those AD797 "military-graded" with different name and marking, not "AD797SQ".