[Andrea]

...when there aren't any oscillation problems?

I've just modified my Go-Vibe, that now has an AD8397ARDZ (exposed pad version) for the LR channels and the stock LM6171 for G. It sounds really great @ 24V. The AD8397 warms up like it's supposed to do with a 11 mA per channel quiescent current.

I'm just looking to put my mind at ease, as I've stumbled on a few posts that didn't encourage using the AD8397 with 24V (was it just for the higher risk of oscillation in the PINT's ground channel?).

Thanks for helping...

 

[tigger]

Quote:

Originally Posted by Andrea ...when there aren't any oscillation problems? I've just modified my Go-Vibe, that now has an AD8397ARDZ (exposed pad version) for the LR channels and the stock LM6171 for G. It sounds really great @ 24V. The AD8397 warms up like it's supposed to do with a 11 mA per channel quiescent current. I'm just looking to put my mind at ease, as I've stumbled on a few posts that didn't encourage using the AD8397 with 24V (was it just for the higher risk of oscillation in the PINT's ground channel?). Thanks for helping...

If you read the AD8397 spec sheet, it specifies 3v - 24v

 

[tomb]

24V? Heck - they were having trouble with 18V and less - determined now in the latest design discussions to limit power to only one 9V battery - not two. Why they decided the higher voltages were the cause of the problems is unclear, and your experience contradicts the supposition, too. In following the build discussions, the LM617x in the Ground Channel seemed the solution.

 

[Andrea]

Quote:

Originally Posted by tigger If you read the AD8397 spec sheet, it specifies 3v - 24v

Yup I know, but I'd been scared by such alarming reports as Tomb's recalled...


At any rate, I'm totally convinced by this modification. Though I'll probably switch to a 12V power supply, just for the comfortableness...

 

[MASantos]

I have used a minified pint with my steps outputting 24v and no problem at all!

 

[n_maher]

Running any opamp at 100% of it's design voltage range seems like an invitation for bad things to happen. Factor in that this particular opamp has a history of "fussiness" and I'd back off even more.

 

[Andrea]

Quote:

Originally Posted by n_maher Running any opamp at 100% of it's design voltage range seems like an invitation for bad things to happen. Factor in that this particular opamp has a history of "fussiness" and I'd back off even more.

But when I had previously listened to the AD8397 only with 12V I hadn't thought it good sounding for my standards... Now it is

I'll try and see if going down to 12V really degrades the sound that much...

 

[Andrea]

Quote:

Originally Posted by MASantos I have used a minified pint with my steps outputting 24v and no problem at all!

Nice... Couldn't you possibly give me some indication as to how warm the AD8397 is at idle in the PINT (with 24V) ? Thanks

 

[tangent]

Quote:

Originally Posted by tomb 24V? Heck - they were having trouble with 18V and less

Yes, but that's also in a circuit with two of the IC channels having a gain of only 1. It's both together that cause the problem, not the voltage alone.

This isn't to say that at G=2 the chip is unconditionally stable. But your chances to go up quite a lot.

 

[MASantos]

Quote:

Originally Posted by Andrea Nice... Couldn't you possibly give me some indication as to how warm the AD8397 is at idle in the PINT (with 24V) ? Thanks

I haven't measured it. I don't usually use the steps for the PINT.

I use an unregulated 9v power supply for charging and only listen using battery power. I can try to measure it if you want me to.

My pint has ad8397 in LR plus Lm6172 on the Ground. They never get hot to thouch with 9 volt battery, but I will try to measure it for you.

 

[tomb]

Tangent,

I was referring to the Mini3 design as much or more than yours. Amb seemed dead set against 2-9V batteries at the last exchange regarding the issues with the Mini3. It should be noted that your implementation had many successful builds, including with 2x9V batteries. Paradoxically, some of those were with the "Mini-fied" mods.

Amb and Morsel, on the other hand, never got to the stage of publicly releasing the Mini3. After a promising set of prototypes, they encountered unsolvable issues in certain configurations. As said, Amb seems determined that one solution is to limit power to only one 9V battery. Even so, they seem to be on indefinite design hiatus with the Mini3.

If in that description above, I have said anything even remotely interpreted as critical (to either one of you), please accept my apology. Nothing could be further from the case. You, Amb, and Morsel have provided immeasurable value to the DIY community with your designs and products. Many of us are frustrated deeply when a product is removed from your respective inventories, or a product in development is not released.

Any of my remarks simply echo the issues that each of you have encountered trying to tame the "raging tiger" AD8397 chip.

 

[Andrea]

Quote:

Originally Posted by MASantos I haven't measured it. I don't usually use the steps for the PINT. I use an unregulated 9v power supply for charging and only listen using battery power. I can try to measure it if you want me to. My pint has ad8397 in LR plus Lm6172 on the Ground. They never get hot to thouch with 9 volt battery, but I will try to measure it for you.

Thanks a lot! But please, only if it's of no bother for you!

 

[Andrea]

Quote:

Originally Posted by tangent Yes, but that's also in a circuit with two of the IC channels having a gain of only 1. It's both together that cause the problem, not the voltage alone. This isn't to say that at G=2 the chip is unconditionally stable. But your chances to go up quite a lot.

That's good to know.


Also, the AD8397 has a 26.4V absolute maximum power supply voltage, identical to that of the AD8610/20. So if the latter can be powered with 24V in all safety, I would reckon that it's the same story for the AD8397... (if free of oscillation of course)

 

[quicksilver96]

My Pint w/ triple 8397s runs perfectly well off of 24v as well. If I recall though many people were only using a single 9 volt as the pint would draw less current at that voltage with little/no performance gain for an increase in voltage. The one I have cased up has slots for two 9v batteries and I only hook up one at a time until it ****s out on me. I don't remember the exact amount of time, but this gets me slightly more playtime per charge.

 

[Andrea]

Today I changed both op-amps.

The AD45048 + OPA551 combination (@ 12V) is the one that hits the sweet spot for me. It sounds wonderful