Capacitor burn in...how long?

I had to get a couple of capacitors replaced in my MX110. It sounds bright after putting her back into play. So.....burn in? I’ve read multiple comments on the subject. Some say 10 hours, some say 75. I’ve also read its B.S. Before the dreadful hum that caused the repair, it sounded really great. What are your experiences with this? Any comments would be really cool. I’ve only got about 3 hours on her so far. So, playing rekkids with the bass turned up to mellow things out.

 

What caps did you use and where?

 

I don't have a direct answer to your question, but I have noticed many comments where people mentioned they continued to hear improvement after 100 - 300 hours of run-in on high-end capacitors (in speaker crossovers).
I have a couple of pairs of older speakers that I like and I plan on rebuilding / replacing the crossovers. While researching the components I want to use, I noticed others experience...
I do not know if the break-in time would vary between use in speakers vs amplifier? Perhaps the larger caps in a speaker crossover would require more time.

 

Ok, well the brand and location of the caps in your receiver matter. I'm guessing your power supply caps were replaced, but no idea what brand, but imagine nothing special like Mundorf. So yes, caps need to burn in and depending on the factors mentioned that could be 100 to 300 hours. You also need to consider that your old caps were way out of spec and what you're going to hear now after burn in is closer to what it is supposed to sound like.

The uF value of the power supply caps in your receiver is going to be considerably greater than caps in a crossover. The voltage value could be greater or less than what's in a crossover.

Quality crossover caps matter, avoid Solen, Dayton and Bennic if at all possible.

 

Great advice for OP.
I know next to nothing about caps but I've had techs advise that the heating & cooling cycle can be more important than constant running time. I'd advise asking your tech exactly what caps were used & their advice.

 

It was repaired by a local guy here in NOLA. It was dropped off at an audio shop and sent out. I don’t think these guys are used to the nerdy questions like what kind of caps or the airspeed velocity of a unladen swallow. I’m just gonna play it and wait for the change

 

What type of caps and where could matter. But personally I think You are not used to the better sound; this will change.

 

Power supply caps are typically used on linear DC supplies after the main bridge rectifier to smooth out the full wave (or some cases half-wave) rectification and after things like regulators for the lower current sections (preamp, EQ/Tone, PA drive, etc...) for filtering, hold up, and lower the impedance/output resistance of the regulator ( Calculate Hold-Up Capacitor Size For Switching, Linear Regulators ) .

For SMPS (Switched Mode Power Supplies) electrolytics are used for output filtering and hold up ( see https://www.st.com/resource/en/technical_note/cd00145610.pdf )

If you look at any datasheet - say Nichicon - see this selection from Digikey:


you'll note things like ripple current and rated life at a certain temperature. Again, depending on the type of power supply (Linear or SMPS) these parameters are selected based on the characteristics of the circuit that's to be powered and in the case of the SMPS the switching frequency.

A great paper on cap selection that can give you an idea as to the equations involved in designing in capacitors is from TI:
http://www.ti.com/lit/an/slta055/slta055.pdf

I will say that I see a lot of techs that arbitrarily select replacement electrolytics. This is not the best idea, since there's quite a lot of difference between electrolytic capacitors that have the same general parameters (ie.. capacitance, voltage, etc...)... one should examine the original caps and the circuit topology to try and ascertain the design intent of the original engineer (who hopefully knew what he was doing.

The rating of the caps life is affected by heating - as shown - and selection of the wrong ripple parameter can have deleterious effects on capacitor heating and consequentially on the circuit function - things like the impedance that the power rails present to the amplifier and it's output stage. And on most power amps, the output stage is connected directly to the unreg rail (where these large caps live in most amps).

Typically when I get people that come to my lab with complaints of sound differences after a recap of the Psup it's usually related to a mismatch of the replacement component and the original topology...

One of the guys I do designs with - Gary Stanfill from the old Vega Wireless - always mentions how electrolytic caps are not so easy to select and can be misleading.

Take a look at these two caps:
LKG2A472MESCAK Nichicon | Capacitors | DigiKey
LLS2A472MELB Nichicon | Capacitors | DigiKey

Note the differences in things like ripple and dissipation factor (tan δ)
Dissipation factor - Wikipedia

So it's possible that what you're noticing might change - it also may not.

It's similar to the whole cable thing and other stuff where the factors involved cause random swapping of stuff to change the transfer characteristics of the circuit. For instance, you don't arbitrarily select cable interconnects in high frequency RF circuits - a certain cable with certain characteristics is used to drive an input of a known impedance from a source with a known impedance.

An example from my marketturd site ( Audio Voodoo and Stuff )

Here's 15,000 watt tube:

That is connected to an FM transmission antenna with this coax:

(Note - the "pipes" in the background are actually what we call rigid line coax)

Now if you randomly muck around with the connectors, or the cable itself you can fry the hell out of that cable - I've seen 10's of feet of that stuff just melt and drop molten copper and brass down on old people that were co-located on Pittsburgh's Mount Washington ( the senior's home was located under one of the towers up there).

Although audio is way below that with relatively extremely long wavelengths, there are some people that swear they can hear these slight differences. In some cases tho, it's really apparent and can be measured.

http://www.cde.com/resources/catalogs/AEappGUIDE.pdf
https://www.illinoiscapacitor.com/pdf/Papers/impendance_dissipation_factor_ESR.pdf
(yea, I know the spelled impedance wrong in the link)


My lab:
Wayne Mitzen - Portfolio

 

Electrolytic Foil caps

 

That doesn't tell me much. What brand and series?

 

Well, information from the place has been lackluster to say the least. I called them back trying not to be the psycho audiophile to get more info, and was told the MX110 was not a good piece of equipment from McIntosh and should not expect it to sound good. I just wanted it to sound as good as it was before the hum. So, anyway, I’m a bit pissed.

 

That's rather unprofessional.

 

I wish I knew what I was doing when it came to repair, but I guess I’m effed.

 

I assume you are asking about audio coupling caps. Power supply caps do not really break-in. My ears did not hear a difference when new to many hours use. On the other hand, audio coupling capacitors definitely have a break-in period. The most sensitive ears I ever known stated about 200 hours for K40Y-9 caps to start sounding good and 250 hours was about fully broken in.

 

In my experience you’re going to have to let it run for about 6-7 years continuously in order for the capacitors to truly burn in all the way and sound their best. It’s also better if you use classical music to do so because of how dynamic it is, it will really make a major difference.