Help With Potential Tube Amp Purchase

[jhull54]

Ok, I have the opportunity to pick up an old Montgomery Wards Airline 6000 amp. From what I can gather from the internets:

Tube complement is 12AU6, 12AV6, and 50C5, which supposedly produces about 3 watts into an 8" speaker.
Tone control doubles as an on/off rotary switch.

I went by and tested the amp, and it works, but upon turning it on, a low hum is emitted, and as the tone is cranked, it drops to a certain point, but still makes the amp unusable. Amp is not very loud, either. #1 input jack does not allow jack to be inserted--definitely fixable.

My question is, does this sound like a recap job, or more involved work to you tube amp experts? I am toying with the idea of recapping it myself, but if it sounds to you guys like it's maybe more involved, might not be worth the $.

Here's a shot of the amp in question. I love old amps like this, and this one dates from probably mid-60s.

Any advice from you gurus is welcome, and thanks!

[Chocol8]

60 Hz hummmmmm could be bad filter caps, or crap wire layout, or bad ground or…

It may just be the bad input jack. The jacks are switched to ground the input when nothing is plugged it. If it doesn’t ground out (or you plug in a cable that’s unplugged at the other end) you can get some nasty humming.

There is still a good chance it needs new filter caps, and it likely has poor wire dress and AC heaters, so it may always have some hum unless you completely rebuild it. Does it have a 3 prong power cord?

[jhull54]

60 Hz hummmmmm could be bad filter caps, or crap wire layout, or bad ground or…

It may just be the bad input jack. The jacks are switched to ground the input when nothing is plugged it. If it doesn’t ground out (or you plug in a cable that’s unplugged at the other end) you can get some nasty humming.

There is still a good chance it needs new filter caps, and it likely has poor wire dress and AC heaters, so it may always have some hum unless you completely rebuild it. Does it have a 3 prong power cord?

It does not have a 3 prong cord. I didn't think about the input jack. That's a good catch. I tried plugging in to that jack, and the plug would not seat all the way. Something is bent inside, probably. Could it also be just a bad tube?

[mickey]

Does it have a 3 prong power cord?

AMEN! Those things can kill you with a 2 prong power cord!!!

[Rollin Hand]

Does it have a 3 prong power cord?

AMEN! Those things can kill you with a 2 prong power cord!!!

I had an old Ford tube amp with a two-pronged cord. Every once in a while, my playing got electrifying in the literal sense.

Highly advise adding a three prong cord.

[mozz]

There should also be a 35W4 tube in there. Those are widow maker amps. Even if you have a 3 prong cord, there is no power transformer so the filaments are all in series direct to the line voltage. You can get killed easily. To properly use one of those, you need to install a isolation transformer. Then any repairs such s filter caps etc. You can't even get 2 watts out of that tube. Cabinets are some sort of pressed cardboard.

[Tonray's Ghost]

There should also be a 35W4 tube in there. Those are widow maker amps. Even if you have a 3 prong cord, there is no power transformer so the filaments are all in series direct to the line voltage. You can get killed easily. To properly use one of those, you need to install a isolation transformer. Then any repairs such s filter caps etc. You can't even get 2 watts out of that tube. Cabinets are some sort of pressed cardboard.

"He killed that solo" takes on a new meaning

[jhull54]

There should also be a 35W4 tube in there. Those are widow maker amps. Even if you have a 3 prong cord, there is no power transformer so the filaments are all in series direct to the line voltage. You can get killed easily. To properly use one of those, you need to install a isolation transformer. Then any repairs such s filter caps etc. You can't even get 2 watts out of that tube. Cabinets are some sort of pressed cardboard.

Mozz, thanks for this info. It seems then, that other than the nostalgia factor, this one probably isn't worth messing with. I certainly don't want to get lit up by one of these b@stards.

I knew there would be some folks on here with great info.

[mozz]

I have a Harmony, same idea circuit inside. Since I got it cheap chances are I'll gut it and put a champ style amp inside. I don't see the collectability in a amp with a tiny speaker and the guts from a tabletop radio, maybe some like that crappy sound.

[JimyTheAssassin]

I get the general concern of a “widow maker” amp. No fuse, mains connected to the chassis, yah yah. But if these things were so dangerous, why did they keep making them. Where are all the dead guys? Personally, I think the fear is a little overblown. Back when these were made, it was regular practice to plug it in one way. If it made too much noise you unplugged it and flipped the plug. The theory here is lower noise would be the result of plugging it in with the correct polarity. These were practice amps so you wouldn’t expect someone to use it with a mic or PA or something else that might be plugged in opposite the polarity of this amp by accident (causing a shock between you and something else). Today people gig with these tiny amps so it’s a problem now because people don’t understand these animals. Anyways I get it, they aren’t “safe”, but if used like intended, you won’t die. Just like the “death cap”. They had a purpose, but someone theorized that if they shorted and you touched the chassis (now hot with voltage), you’d die. How many times has this happened. . I digress. We need to idiot proof things for good reasons.


Sent from my iPhone using Tapatalk

[Chocol8]

I don’t know how often people died, but there were a ton who got shocked. Plenty of fires as well. Also, the danger goes up with age for a variety of reasons.

[mickey]

I have never witnessed anyone get killed, but I have seen a guy get knocked out cold and hauled to a hospital!
He was playing a guitar connected to a "widow maker" amp and singing into a mic connected to a (P.A.) different amp.
His lips accidentally touched the mic & he hit the floor!

[mozz]

Guy from the Yardbirds was killed. Just cause one way hums less does not mean it was the correct polarity.

[andrewsrea]

^ Keith Relf from the Yardbirds: one hand on the guitar, plugged into a poorly grounded amp + one hand on a cold water pipe = coronary arrhythmia.

I agree with posts here. Display it as a part of history.

Valco (the builder of Airline, Supro and other branded amps) and a few import manufacturers produced transformer-less designs because the transformers were (and still are) the most expensive part of the design (and make shipping and handling expensive). I can tell you first hand that they sound bad, even when working well. Even brand-new, they had a prominent hum and generated unmusical harmonics which made them bland sounding.

Their idea was with good intent: copy the concept of automobile radios, which operated off of 12vDC or 6vDC power and transformer-less output tubes. These were very low watts and were no means, HiFi. But they worked safely.

For this amp, you spend $ hunting down the odd-ball tubes in the hopes you have good ones, need to recap and install the grounded mains cord. Only to find a tone that only eclectic players would find useful (IMHO).

[JimyTheAssassin]

Good points of course, and I can’t disagree. I just imagine death was rare (widow maker) . Death is still permanent though. The poor guy from the yardbirds got the full British voltage too. 230v will sure light you up.

By the by, back in the day when this was more common, would these radios and amps not have been recommended to be tied to a physical earth ground rod (or pipe connected to ground). Wouldn’t that lessen or mitigate the extreme potential of death? Maybe you’d get away with just a tingle or shock

I was imagining connecting to one with a wireless transmitter. That would be much safer. But the tone is still not great (so people say). Could it be some to do with half wave rectification?

Sent from my iPhone using Tapatalk

[mickey]

Not really, no, they would not normally have the chassis connected to a water pipe or some such earth ground.
Why? Because if you plugged the 2-wire power cord in backwards copious quantities of magic smoke would be released.
At least until the fuse in the fuse box (breakers were not the norm back then) smoked.

And if someone like my grandfather put a penny behind the fuse instead of finding a good replacement fuse
the last time it blew, the whole house might just go up in smoke. Which is why we have breakers today.

[Chocol8]

The poor guy from the yardbirds got the full British voltage too. 230v will sure light you up.

He likely got over 400 volts. With a transformer, the B+ is stepped up usually over 400 volts, sometimes 500. It doesn’t matter what side of the pond you are on because the proper transformer will step up the line voltage to the design B+ voltage. Then there’s the big filter caps to make sure you get plenty of current to go with the voltage. OUCH!!!!

Things like 3 prong cords and circuit breakers were not things some safety guy decided would be a good idea. They were lessons learned the hard way.