Breaking in Teflon Caps

[Stefanoo]

Hi John,

thank you for your post.
So do you just connect the cap in parallel to the signal generator feeding a square wave of 700Hz?
No DC offset added to the signal?
No resistor anywhere to limit perhaps current (with a sqaure wave with low falling/rising time, the output of the signal generator will drive a pulse current close to the limit of the output stage capabilities, is it bad?) ?
Why 700Hz? is it just a random value you picked or there is a reason for choosing that frequency?

[analog_sa]

Originally Posted by kevinkr

I would just install them in the amplifier where they will be used, under the exact conditions they will experience in normal operation.

What about the innocent tubes in the amp? Use your Chinese spares?

The only teflons i have experience with were russian FT3 and i probably didn't give them a chance to break in - so horrible was the sound. As a general rule i don't use parts which don't sound decent within 24 hrs - life is too short.

[john curl]

Don't worry too much about the details. An associate made a 555 timer version of a break-in device that worked with a lowish frequency square wave. This seemed to work pretty good for everybody who used it. The generator will current limit, if it is not a power amp, at least. DC is not usually necessary. It seems that the better quality caps, like Teflon take longer and are harder to break-in. Why this is so, I don't know, but it is pretty darn consistent in experience.

[analog_sa]

Several years ago i wrote some simple code and used a micro to sweep 10Hz-20kHz. Used a chip amp to boost the voltage at output. The break-in effect was nowhere close to real music.

[Salas]

Did you try pink noise?

[Salas]

Originally Posted by analog_sa

What about the innocent tubes in the amp? Use your Chinese spares?

The only teflons i have experience with were russian FT3 and i probably didn't give them a chance to break in - so horrible was the sound. As a general rule i don't use parts which don't sound decent within 24 hrs - life is too short.

Very many people have been using the FT-3 or FT-2 as a cost effective interstage Teflon coupling cap when making that simple phono stage I have posted for almost a year now, and they report only good stuff in its thread. But I have heard ''everybody raves about Teflon but I just hate it'' from a guy that makes really good gear that I have experienced and like. He has very good taste and wide experience in music and audio. Go figure...

On the second part... I am like you. If something does not show 80% of its colors in 48h, I just can't give it much more thought. Interestingly, the guy above said ''all good with Teflon during the first 24h, then its a mess''. Which contradicts the popular consensus that they are stiff at start. Go figure no 2...

The ''I have been told this and that'' rears its ugly head once more. It takes to check stuff out in one's own things.

[Stefanoo]

Originally Posted by john curl

Don't worry too much about the details. An associate made a 555 timer version of a break-in device that worked with a lowish frequency square wave. This seemed to work pretty good for everybody who used it. The generator will current limit, if it is not a power amp, at least. DC is not usually necessary. It seems that the better quality caps, like Teflon take longer and are harder to break-in. Why this is so, I don't know, but it is pretty darn consistent in experience.

I have a wavetek signal gen, I haven't measured the maximum output current yet, nevertheless specs say that it is capable of 20Vpk-pk on 50ohm, thus a maximum current of 0.4A pk-pk (140mA RMS) I guess.
Would this be too much for the braking in or can I safely connect all them in parallel?
What about swapping the direction of the caps not to brake them in unidirectionally as somebody suggested on previous posts!?
Is it true?

Sorry if I overstress on these details, but I want to make sure I am not ruining the sound's potential of these expensive caps.


Many thanks

[Conrad Hoffman]

Hi Stefano,

I don't have a clue as to the sonic benefits, but it would be easy to rig up a relay and 555 timer to reverse the caps at any interval you like. We're really talking about the same thing, just at different frequencies. A DC offset with occasional reversal is just a very low frequency square wave. A good rule is "test it the way you'll use it" and that probably applies to break-in as well. If the cap will have a bias voltage, why not break it in with the same bias voltage?

As for the Wavetec, it does 20Vpp and it drives a 50 ohm impedance, but probably not both at the same time, and the specs might not say. I'd use a 50 ohm resistor in series with the cap for any square wave or high frequency tests to protect the generator. If you need more power, rig up a power amp of some sort.

It would be really interesting to split a bunch of caps into two groups. Burn in one group only. Then, swap them in and out of an amp and see if anybody could really tell the difference. The caps would have to be matched in value. My experience with Teflon caps is zero because they aren't available in any useful value to me. IMO, admittedly a WAG, is that some of the sonic characteristics of Teflon caps result from people using too small a value for the application, because it wasn't practical to get the necessary value, and because the results of slight roll-offs on overall sound quality aren't appreciated as much as they should be.

CH

[Stefanoo]

Hi Conrad,

nice to hear from you...it's been awhile. Thanks for your post.
My experience with poliprop caps is that broken in caps usually sound smother, richer and more detailed, while when brand new they are a bit sharp and not as "liquid".
People say Teflon caps are though. The manufacturer suggests a minimum of 200 hrs braking in time.

So I guess a square wave would be a good signal since it reverses the caps at each half cycle and spectrally wise speaking it contains all frequencies.
I will therefore connect all the caps in parallel with the black wire (outer foil) to GND and the red wire to the generator throught he 50ohm.

I do tend to think the same thing: the best would be to brake them in the circuit they will be used on but, since I am still missing parts, the circuit is not completed yet.
Either way the caps need a lot of braking in time and since the actual circuit heats up a lot ...I would rather have the generator on for 24h than my stove....I mean circuit

[john curl]

I doubt that you can hurt the caps by breaking them in, or the test equipment either.