Axial Blue "Molded" Capacitors - Who made them?

[mabinogeon]

Hi all,

This is one of those questions that doesn't really matter, but I'm curious anyway.

I've heard the tubular blue molded caps in '60s Fender amps variously referred to as "Ajax", "Mallory", and "Sprague", but I just stumbled across a couple NOS .1µF 1000V caps that are labeled Packard-Bell.

caps1.jpg

The top two .047µF caps in that picture are the ground switch caps out of two '60s Fender amps I own.

Someone elsewhere suggested these might be two different types of capacitor, but I think they’re the same, they look pretty similar to me: same paper label, same color casing, same bump on the outer foil-side endcap.

caps2.jpg

It looks like some "Molded" caps have square-ish ends and some have the more familiar rounded ends. I assume this is due to capacitance and voltage.

Here's a "Molded" .022µF 200V with square ends: https://www.ebay.com/itm/183750617568

Here’s a "Molded" .022µF 200V with rounded ends: https://www.ebay.com/itm/133536342757

And here's a pair, one with a "Molded" label and one with a Packard-Bell label: https://www.ebay.com/itm/123182357161

Someone else suggested Micamold Tropicaps or Astrons, but I can't find where either of those ever made a 1000V cap or made one in blue, and the construction appears different based on what I'm seeing on eBay. But who knows what was going on 50+ years ago...

Perhaps we've been dealing with two different types of capacitors all along and just didn't know it? Perhaps we'll never know for sure?

Does anyone happen to have a definitive answer on this? Do we know conclusively who made the blue Molded capacitors? Did Packard Bell manufacture their own components for use in their radios and TVs and computers back then? Or were these made by someone else and rebranded Packard Bell (that is my assumption)?

Is there a datasheet for these floating around out there somewhere?

Thanks for your time!

[maxkracht]

I'm curious about this as well. I would assume it is an OEM situation and difference in mold shape might indicate design change over time. Could also be something like "orange drop" or "greenies", or the ubiquitous yellow axial caps; many manufacturers, similar look, usually similar composition, but not always the same thing or same quality.

[mabinogeon]

Some but not all blue Molded caps, whether they have the paper labels, the yellow text labels, square or rounded endcaps, or are branded Packard-Bell, are stamped "MC1" followed by a date code. So I think from that we can surmise they are all the same type of capacitor from the same manufacturer, but we're still no closer to confirming who that manufacturer was.

MC1 Caps.png

Perhaps the MC stands for Molded (or Mylar) Capacitor?

Fender started using them in 1961, as far as I can tell.

There was also an Ajax 705 series ceramic-shell mylar cap from the same time period, which leads me to believe the blue molded aren't Ajax caps: https://reverb.com/item/27981789-ajax-0 ... guitar-amp

[mabinogeon]

I emailed Fender and this was their reply:

"I ran your question by two of our senior amp techs and here was their response:

I can't say that I'm 100% certain, but I believe I'm very close to 100%. It has always been my understanding these were Mallory Capacitors. I have also heard that from some of the guys in R&D. That being said there were never any documents left laying around in old dusty file cabinets that specifically says what they are. I base my understanding from what I saw back in the day. My father was a member of MARS which was the Military Amateur Radio Society. As such he worked on a lot of old military communications equipment. The blue capacitors used in those products looked just like these and they Mallory stamped on them. GK is also correct in that MC designation would stand for Mallory Capacitor."

So there we have it! Mallory, probably most likely

There has to be a datasheet out there somewhere, so I will keep looking.

[martin manning]

Great to get some "official" response. That seems to agree with the consensus on the internet, where they are sometimes referred to as Mallory Ajax.

[Stevem]

The root manufacturer was Astron as shown in a page from my 1958 supply catalog.

Also here's the other main manufacturer of caps as seen in amps here in the US.

Would it not be great to have Mullard tubes available at these 1958 prices?

[mabinogeon]

The root manufacturer was Astron as shown in a page from my 1958 supply catalog

The "Astron Blue-Point" caps are the yellow caps we see in late-model Tweed amps and were so called because there was a little blue dot visible where the lead exited the body of the cap.

bp.jpg

As we know, they leak as they get older. They were paper dielectric until some point in the early ‘60s when they changed to a paper/plastic hybrid dielectric.

Here’s some ad copy on the Blue Points from 1953: https://worldradiohistory.com/hd2/IDX-S ... e-0035.pdf

There were several other capacitors that had molded bodies similar to the blue “molded” caps I started this thread about, including the Sprague Black Beauty series (paper dielectric), Sangamo 33M series (mylar dielectric), Pyramid IMP series (paper dielectric), Pyramid Type III series (plastic dielectric), Mallory GEM series (paper dielectric, then changed to mylar), Aerovox P88 series (paper dielectric), and many others. It seems to have been a common shape back then.

[SoulFetish]

Is there any reason to believe that these weren't made by Ajax Condenser Co.? The "705" was their EIA code.
They were originally based out of Chicago, IL, but expanded to open up a west coast factory in North Hollywood, CA. as well.

[mabinogeon]

Is there any reason to believe that these weren't made by Ajax Condenser Co.?

Just that Fender says they're pretty sure Mallory made them.

[Charlie Wilson]

Is there any reason to believe that these weren't made by Ajax Condenser Co.?

Just that Fender says they're pretty sure Mallory made them.

No, a guy at Fender who's dad was a ham radio guy said they look like Mallory. That to me says his guess is as good as ours. The Packard Bell thing is interesting. I have never seen that labeling before. However, Fender did use Mallory electrolytics during the blackface era and into the seventies. Bob Rissi might know for sure. I guess I can't ask him, I see that he passed away this year.
CW