Boutique Caps

[oldguide]

I have been slowly rebuilding an old Dynaco preamp which I use as a phono stage. In the process I seem to have stumbled down a rabbit hole in regards to caps. The main topic of discussion on many other boards seems to be about what are called boutique caps--exotic creatures that can run several hundred dollars for ONE cap. Just a short aside--to replace all the caps in my Dynaco with boutique caps would run anywhere from $300 to close to $1,000. So in the interest of perhaps stirring up a thread (some of them go on for 15 pages) I thought I would broach the topic here and see what some of the old hands have to say.

These things are built of all sorts of materials, so many that I half expected to see one built from cow dung. Several sites purport to "rate" the sound of these critters on a one to ten scale the way they do for wine. The write-ups on how these caps sound uncannily resemble wine reviews as the writer searches for new metaphors to describe the differences in sound. Here's one: "X had a bit more richness to voices and even more apparent smoothness in the upper-midrange region, but it conceded some sheer resolution and attack."

I won't bore you with descriptions of all the options other than to note a couple of themes. First, it seems the more you pay, the longer the so-called "burn in period." It is not unusual to see one with a burn in of 400 hours--which is two weeks of 24/7 listening. I figure after two weeks of solid listening and spending several hundred for a couple of these I would think I had arrived in heaven and was hearing angels. Second, the big drivers of this seem to be guitar freaks, DIY types and modders searching for the elusive pure sound. Third, for some reason these folks also have an antique streak so they are willing to pay what seem exorbitant sums for electrolytic and ceramic Spragues, Black Cats, and other old timers. I swear I saw the Spragues I removed from my 4xs on fleabay for double what I paid for their replacements. Fourth, as a systems person it seems to me that caps are only part of an overall system and without knowing the system, the application, etc (in other words a complete wiring diagram) these subjective tests--which rarely detail the application--are akin to voodoo.

The manufacturers are more than happy to keep coming up with more of these exotic creations along with the Russian military which already is doing a booming business in unloading old tubes and now is selling old caps. My instincts scream that what one writer referred to as the Great Cap Wars are in fact the cap equivalent to the long-standing Cable Conundrum.

What I don't get is the subjectiveness. I am no EE, but you should be able to measure some of this. One poster, who is an EE did run a cap test in which he concluded his instruments could find little difference, which of course got all those people who had invested mucho bucks to flame him off the site. Yet no one took up his challenge to show objective testing data.

So what do board members think? Are the Cap Wars equivalent to the Cable Conundrum? Has anyone used these $100 crittters in an AR rebuild? Is there an elusive "best cap" for ARs?

[johnieo]

Fourth, as a systems person it seems to me that caps are only part of an overall system and without knowing the system, the application, etc (in other words a complete wiring diagram) these subjective tests--which rarely detail the application--are akin to voodoo.

Old Guide:

your last comment above hits it on the head. The capacitors used in loudspeaker crossover networks are filter capacitors- separating low, high or passbands; that is what almost all the discussion on this forum is about. (There are two cap applications -- LST and AR-9 -- which are not part of a crossover.) Manufacturers used both non-polar electrolytic (or Mylar in some cases for hgh-frequency filters). Personally I have chosen to replace NPE with polypropylene or Mylar in any crossovers I restore so that my grandchildren will not have to deal with replacing them long after I'm gone! Ditto for finding old cloth surrounded drivers when possible.

Amplifiers use capacitors for many tasks: power supply filtering, tube or transistor bias, feedback, and coupling, etc. One always uses polar electrolytics for the power supply; some folks place a small bypass cap in parallel. Nothing fancy here, although I would purchase a low ESR, longer-hour rated device if possible--some of the electronic items we produce today are designed to be tossed in less than the 2000 hr ratings of the lowest priced electrolytics! Coupling and feedback capacitors should be of good quality, as they pass the entire frequency spectrum: I would use polypro for these, but would not spend big bucks on a fancy brand. DC blocking/bias caps--not so important in general, but could be in a specific circuit. The bottom line is that you need to understand the circuit diagram to see which are feedback and coupling caps, and spend more than twenty cents on those!

The difficulty in interpreting capacitor comments--here and other places--is that the application may not always be stated.

Cheers,

John, who has likely opened another can of worms

[genek]

So what do board members think? Are the Cap Wars equivalent to the Cable Conundrum? Has anyone used these $100 crittters in an AR rebuild? Is there an elusive "best cap" for ARs?

I am of the view that the differences between caps are mainly in how accurately they hit their rated specs and in their longevity. But then again, I'm still using lamp cord from Home Depot for speaker wire and I haven't felt the need to recap any of my ARs yet.

[oldguide]

The bottom line is that you need to understand the circuit diagram to see which are feedback and coupling caps, and spend more than twenty cents on those!

The difficulty in interpreting capacitor comments--here and other places--is that the application may not always be stated.

Cheers,

John, who has likely opened another can of worms

John,

You were one of the ones I had hoped would comment and your comment helps me a great deal with my conundrum about the Dynaco rebuild (not that I can afford a $100 cap)--but I should let that drop in this forum, except to say thanks.

Yet researching this I find folks in the Polk and Klipsch forums as well as suspects who shall go unnamed going on and on about the virtues for speaker crossovers of teflon and boiled in oil and gold and silver and aluminum foil and even beeswax, monster Russian cans that look like your are supposed to pull the pin and run for cover and secret liquid concoctions that had me thinking of Love Potion Number 9. So it is not just an amp thing (although the guitar folks are another breed--and maybe, to give them the benefit of the doubt they should be since they ARE artists and just like pianists they want their instruments tuned just so, I can understand it).

Also, what do you make of the stampede to buy old capacitors on fleabay, many of which, judging by the ads, are pulls so you have no idea what you are getting? I swear someone is gong to claim the old AR wax bricks are the ultimate.

Thanks again for your wisdom.

[Carlspeak]

If you haven't browsed the capacitor debate within CSP, I refer you to 3 threads on the subject created within the last couple of years.

Here's a link:

http://www.classicspeakerpages.net/IP.Boar...c=3859&st=0

In the AR discusion area there are 2 additional threads

1) Capacitor myths

2) Capacitor myths revisited.

So, Oleguide, if you're ever bored and want to become more confused, read more about it......

[rrcrain]

Morning,

Around a year or so ago, I replaced the 10uf NP coupling caps in both of my amps. Not suprisingly, being electrolytics over 20 years old in a solid state amp that has a heat sink temp over 100 F at idle, they were wearing out.

In my humble opinion, it was a waste of money and effort to have replaced te electrolytics with Polypropolene(sp) in this application. Yes, the new caps did restore the amps frequency responce but new electrolytics would have done the same thing.

Use good caps, but don't get carried away.

[Pete B]

http://www.classicspeakerpages.net/IP.Boar...capacitor+myths

http://www.classicspeakerpages.net/IP.Boar...mp;hl=axon+poly

[oldguide]

Thanks for the links. I had honestly forgotten about this thread, but it has been six months since I read it and to this old mind that's a long time. I apologize for obviously bringing up a rather dead horse. Sounds to me like everyone is on the same page here.

Pete, just a note to also thank you for all the links in the original thread. I learned a great deal from that reading.