Questions about caps vintage vs. new

[S4XAmps]

I recently have acquired some vintage caps on ebay some used and some NOS. I also have new caps from Mouser and other suppliers. I have not started use vintage stuff yet but was wanting some opinions if it really makes a difference when using the vintage vs. new stuff. My vintage stuff is Sprague OD's mustards, goodall, TRW, black cats, bumbles, black beauties, and domino micas. My new caps are Sprague OD's, Mallory, and Sozo's. I got most of the vintage stuff on ebay and can always resell them.

[cartoonweirdo]

I first need to make a distinction and say that all NOS electrolytic caps (also known as power supply caps, filter caps, or cathode caps) are TERRIBLE!! this is because the electrolytic goo in them dries out over time (even in use, but especially when sitting around) and by the time they qualify for NOS they are useless.

I have tried many of the vintage caps you have listed and have found that they sound much better than bad modern caps but about as good as good modern caps.

You are of course going to ask what the good and bad ones are, but to me that's subjective. Also, coupling caps of any brand are right for some jobs but suck in others. The thing is that you are looking for your guitar amp to have a certain sound, or tone. Many things contribute to that tone, and filter caps seem to be somewhere between 3rd and 5th in importance.

In my experience, bad filter caps will make a guitar amp sound farther away, less warm, overly bright or bassy, plastic or artificial, and etc etc. Good ones will sound full, rich, more present, and more magical. Since none of these parameters can be measured by anything but your ears you will have to solder caps in and out of your amps to hear the difference for yourself.

I recieved a great afternoon of education listening to an old fender head (chosen for ease of changing caps) through it's stock speaker cab with different caps. You can try changing to all one brand or you can mix and match (especially cool in the tone stacks). I know what my personal favorite for that head was (new mallories) but all the caps sang in different, and useable, ways. This information, of course, is also interactive with the individual irons, tubes, speakers, or circuit. For instance a set of caps will be overly bright and ringy if the "wrong" 12AX7 is in the circuit. A duller tube will make them sound "right".

I know this sounds hard to figure out (it can be) and pretty subjective (it is) but general trends do emerge eventually, and you would be best served as a repairman or a builder to be aware of those trends and use them to your best interests.

Good luck,
Carl

[wyatt]

The problem I have had with many NOS caps is that they are very often highly out of tolerance, but worse yet, they often leak DC, losing signal through the amp.

Now I lean toward premium modern caps, Sozo, Jupiter, etc.

[S4XAmps]

I would test the caps for leakage and spec before use but your right, they can be out of range. Those Jupiter caps are pricey! Are they worth it? I was checking out some of the other caps at Sonic Craft, are some Hi-Fi and some guitar?

[Geek]

Hi,

NOS caps may need to be reformed.

Assuming the electrolytic hasn't dried out, you can rectify **isolated** high voltage (that comes within 10% of the caps maximum rating when filtered) and feed it through a 1 Meg, 2 watt (for voltage rating) resistor to the cap. Let stand like this for 16-24 hours.

Measure the voltage. If it is within 10% of what you fed it for voltage and it holds it after you unpower it, call it a success and discharge the cap safely and you're good to go :)

If it's 25% or less, it's leakage is too much and she's shot Yellow_Light_Colorz_PDT_13

There are faster ways of doing this, but like charging a NiCd, I found it's better the loooooong way around

Cheers!

[wyatt]

I would test the caps for leakage and spec before use but your right, they can be out of range. Those Jupiter caps are pricey! Are they worth it? I was checking out some of the other caps at Sonic Craft, are some Hi-Fi and some guitar?

The Jupiter are worth it if I really want to build or (more likely) repair a vintage amp to vintage spec, particularly guitar amps. The same use and same reason I would use carbon comp resistors.

If I'm building from scratch, I see no reason to go Jupiter, I can use any number of good caps...for guitar amps, Mallory 150, OD, Sozo, etc. Hi-fi? Well, the Jupiters are dirt cheap compared to many hi-fi caps, and I'm no snob, so I 'll lean toward something nice, but affordable.

[S4XAmps]

Is there a good or bad tone if one used hi-fi caps on a guitar amp?

[Geek]

For coupling caps, etc., HiFi caps can ruin an amp.

I did an "un-furbish" on a vintage Fender Vibrasonic (a "pro" upgraded it and ruined the tone) and replaced all the WIMA caps with the origionals (ceramics and all) and it brought that amp back to life.

Some caps can be used for both - Orange Drops and the yellow polyester (not polypropylene) film caps can improve things.

After much testing, I found even the drifty ceramic X2 safety caps can improve tone with their non linearities and I use those in my amps.

Cheers!