Vintage Orange Drop Capacitor Quality

[Gamedojo]

I am not an electronic Engineer, but I observed something strange, and wonder if anyone here may know better.

I'm building a vibroverb from scratch, and took some time to slowly gather NOS components (caps, resistors, pots..etc) if I could find them relatively cheap.

I check for outer foil and inner foil arrangement to help a bit with noise/interferience and this is when I noticed something strange:

With brand new SBE 6ps Orange drops, my osciilliscope bounces all over when I squeeze the cap with my fingers. Rather dramatic, but when I do the same process with my 4ps and 6ps caps from the 60s, some would bounce slightly, but others wouldn't even move the scope no matter how hard I squeezed or set the scope. Keep in mind, these are the same value caps as the new versions.

It wasn't subtle.

Is there a reason for this? Is it simply age that drys something out or is it capacitor quality better back then? I'd assume my squeeze test shows the vintage ones would be less suceptable to interferance or something...

...just a friendly observation. pic of build below for fun:)


[img2672]http://www.tylergrund.com/images/vibroverb_tyler.jpg[/img]

[Jana]

That sounds like what I have experienced with them too. If you take a wooden dowel and "ding" the caps while observing a sine wave on the scope you will probably see some hash or noisy spikes. The caps seem to be quite susceptible to picking up physical vibrations as well. You can mitigate that somewhat with a glob of silicone underneath or between caps if they are close together. Sort of creating a shock absorber for them.

They are also fragile with the way the lead is fastened to the foil innards and can sometimes make intermittent contact. Sometimes the contact is dependent upon any vibrations in the amp chassis and will sound horrible.

I'm not an EE either, nor do I play one on TV.

[selloutrr]

are you testing the caps to make sure they are good before you test foil position?

[Structo]

When you touch the cap between your two fingers, aren't you messing with the capacitance of the cap?

Rather than compressing the cap I would think you are altering the capacitance a little bit.

[David Root]

I've had this same experience with new 6PS caps. I can feel them physically squishing a bit as I squeeze them. They spike/hash whichever way you connect them. I just assume the connection with the lowest spike/hash is right.

Haven't had enough old ones around to compare with but it would not surprise me if they were better built years ago. First Switchcraft jacks, now 6PS caps, what's next?

[Cliff Schecht]

Tube sockets...

[67plexi]

I sure miss the Mallory PVC caps just used the last stock I had.
On the SBE caps one thing that helps is to silicone glue the cap to the board a syringe works well
You can hardly see the silicone. I have observed the old 6ps to be a high quality product.
The ROE Roderstein and Philips are high quality film caps.
Obtaining high quality parts is becoming a witch hunt.
Thanks China…………. Not.