Why i don't trust / like tantalums

[Khron]

The title's a bit of a spoiler : "Big reveal" section starts around 20:12.

https://youtu.be/9inGSp2QnfI?t=1212

 

[abbey road d enfer]

The title's a bit of a spoiler : "Big reveal" section starts around 20:12.

https://youtu.be/9inGSp2QnfI?t=1212

Most of sensible audio designers avoid them. I don't know how Neve deals with them failing...?

 

[Khron]

I guess they just go with the "it's not a bug, it's a feature" attitude? ;D

<cough>tantalums-in-vintage-mics-and-DIY-clones-thereof<cough>

Most of sensible audio designers avoid them. I don't know how Neve deals with them failing...?

 

[RuudNL]

Geoff Tanner (ex Neve) always says that "these tants aren't there without a reason".
He also discourages to replace them with aluminium capacitors, "because it changes the sound".
I seldom had a defective tantalum as a coupling capacitor, most of the time they fail when used over the supply rails.

 

[Khron]

Weren't they just (at least considered) better than the electrolytics of the day? And they just "stuck"?

Geoff Tanner (ex Neve) always says that "these tants aren't there without a reason".
He also discourages to replace them with aluminium capacitors, "because it changes the sound".
I seldom had a defective tantalum as a coupling capacitor, most of the time they fail when used over the supply rails.

 

[Winston OBoogie]

I seldom had a defective tantalum as a coupling capacitor, most of the time they fail when used over the supply rails.

+1

 

[[silent:arts]]

Weren't they just (at least considered) better than the electrolytics of the day?

Yes. And smaller. And the electrolytics will work in the circuit. And I'm sure neither Neve (or Neumann) choose them by ear.
But if you don't want to change the sound, use the same parts (in the audio path).

 

[Khron]

... Although one must wonder how much of the "sound" is due to the aged (and potentially degraded / failing) nature of the cap. Which will likely not necessarily be just as when it was new, sooooo...

Totally agree with the "not chosen by ear" part though ;D Because duh...

Yes. And smaller. And the electrolytics will work in the circuit. And I'm sure neither Neve (or Neumann) choose them by ear.
But if you don't want to change the sound, use the same parts (in the audio path).

 

[[silent:arts]]

... Although one must wonder how much of the "sound" is due to the aged (and potentially degraded / failing) nature of the cap

The benefit of tantalums is their longterm stability, aging is no a problem.

 

[analogguru]

....
I seldom had a defective tantalum as a coupling capacitor, most of the time they fail when used over the supply rails.

Exactly..... especially when they are used near their limits e.g. a 25V rated tantalum at a 24V power rail or a 10V tantalum with a 9V power rail.  Tantalums don't forgive overvoltages - some spikes at the power rails and they are gone.

 

[ruffrecords]

Most of sensible audio designers avoid them. I don't know how Neve deals with them failing...?

Neve used them back in the 70s because they were the most compact high value capacitors available at the time. This was before aluminium electrolytics had been invented and regular types were pretty big.

Neve only used them for coupling caps and gain setting caps. They were usually sized such that their impedance was negligible compared with the load and hence they made no contribution to the Neve sound, despite what my old mate Geoff Tanner may say.

Cheers

Ian

 

[abbey road d enfer]

Geoff Tanner (ex Neve) always says that "these tants aren't there without a reason".
He also discourages to replace them with aluminium capacitors, "because it changes the sound".

I find it hard to believe. IMO it's just perpetuation of a myth.

I seldom had a defective tantalum as a coupling capacitor, most of the time they fail when used over the supply rails.

They do fail dramatically when exposed to overvoltage, but also they sometimes leak in a very sneaky manner, so they "work" but they also tend to displace the operating point, which changes the "sound" in a gradual manner that makes it hard to detect.

 

[PRR]

> Neve used them back in the 70s ... before aluminium electrolytics had been invented...

As I bet you know, Al electros go back before the 1930s and were VERY common in mid-1930s radio sets.

They drifted and leaked and went bad. 1950s Tants in aerospace work were much better caps. By the 1970s Tants were in wide use in audio. But Tants have problems of cost and sourcing and unforgiving overload. The Al electro cap makers saw the target and modern Al electros are very much better. (But also available cheaper than ever; buyer beware.)

 

[ruffrecords]

> Neve used them back in the 70s ... before aluminium electrolytics had been invented...

As I bet you know, Al electros go back before the 1930s and were VERY common in mid-1930s radio sets.

Absolutely right but their development since then has been almost continuous. Early types were wet electrolytics, dry electrolyte types began to appear in the mid 60s but still did not have the volumetric efficiency of tantalums. Then in the 80s and 90s various new solid electrolyte were developed that significantly reduced ESR and  enabled higher temperature operation.

Cheers

Ian

 

[PRR]

Dry electrolytics were commercial at the end of the 1930s.

Yes, Tants were smaller than Al for many years.

 

[ruffrecords]

Dry electrolytics were commercial at the end of the 1930s.

Didn't know that and I cannot find any info on dry elecs at that time. Who made them?
[/quote]

Cheers

Ian

 

[RuudNL]

To be honest: I never heard much difference between capacitor types.
(Maybe I always used "the good ones"...)

 

[gyraf]

Neumann invented Ni-Cad batteries like a type of dry electret for their microphone heater voltages..

 

[emrr]

My RCA BA-71’s rebuilt with tants sound substantially different than those with standard electrolytics.  I’ve 4 of each.  Distortion.  The tants are great on drums, not much else. 

 

[abbey road d enfer]

My RCA BA-71’s rebuilt with tants sound substantially different than those with standard electrolytics.  I’ve 4 of each.  Distortion.  The tants are great on drums, not much else.

Have you positive proof that tantalums achieve better performance than Al in this circuit.
The output stage is really optimized for 600 ohm load. Deviation either way, lower or higher load, results in assymetrical drive.