Airline Amp Revamp

In Which I do not Ignore the Forces of the Universe

This one popped up locally. I had no idea what it was except that it was an old tube amp and it was very funky. I’m not a big amp guy but know enough to get into trouble, and this is how it starts.

So it’s a small Airline amp, advertised as “working” if you wiggle the little tube just right. I’d been thinking about a small tube amp because my Premier 100R is a bit large for my needs (and the living room). The cool factor had me at first sight but it’s about an hour away and I have a little scar tissue from my other vintage tube amp so I managed to take a breath and do a little research.

On the chassis I can read “Montgomery Ward Amplifier 85GDR3731” and start searching on that, which ultimately funnels me to the conclusion that it’s an Airline model 3731. Turns out “Airline” was a private label brand for Montgomery Ward, similar to “Silvertone” for Sears. These were made from 1958 to 1964 by either Valco or Danelectro. I was able to find a digitized version of the 1958 Montgomery Ward Christmas book and sure enough, there it is on page 199 (below, courtesy of musetechnical.com). But after that I couldn’t find much information. There aren’t a lot of them out there at this point, so they were either not popular, not durable, or both. I did find one that sold on Reverb, it was in pretty amazing condition and the price reflected it.

I sent some pics and questions to Seth at Red House Amplifiers. Seth is an amazing tube amp guy who I got to know via his repair of my Premier 100R. He came back saying it’s a simple small amp, similar circuit to a Champ, and that whatever’s wrong wouldn’t be too bad to fix. A Fender Champ is one of the legends of electric guitar amps so now I’m thinking maybe I can sneak into Champ territory with this little cutie. However, on the flip side there are some nice NEW small tube amps on the market now, in the $200-$300 price range, which is what I will likely spend on this one, maybe a little more. And the new ones work! And have reverb! But alas the new ones have no soul. This sets off a familiar internal argument…I take another breath and let my subconscious fight this out in the background…

But my subconscious has barely gotten warmed up when up pops a guy in the same hour away town, wanting to buy some golf balls that I have for sale. This is the kind of coincidence that you ignore at your peril…suddenly the amp could be discounted by the golf balls, it’s a sign! Right?

It wasn’t simple but eventually I was able to wrangle a time to meet both people. But as I’m on the way I get a text from the amp guy saying that now he can’t get it to work at all, so unless something changes I won’t be able to hear it…hmmm. I hesitate…this is a bummer and goes against my son’s cardinal rule about buying anything musical: “if you can’t play it don’t buy it”. And that’s a good rule in general, but I’m getting signs from the Universe here so he needs to mind his own beeswax. I soldier on.

You never know on these meetups, but I’ve met some really interesting people this way and this was another one. Really nice and enthusiastic guy who was very into music and electronics. He appreciated the amp and tried to get it working but couldn’t, so he cut the price…and 10 minutes later I got the same amount of money for the golf balls.

So I tell people I traded golf balls for it.

I get it home and started to look it over. It’s kinda crunchy…some oxidation on the aluminum, the cabinet is a little bunged up, the speaker cloth is pretty groaty, the leather handle has some cracking, and all that’s left of the logo is the “A”. So basically it’s perfect :-).

I have plenty of other things going on so resisted the urge to start tearing it all apart and decided to run it down to Seth and let him check it out. I’m in no rush and after the nightmare I visited upon him with my Premier amp I’m in no position to expect anything special service-wise, but after about 10 days I get a text that its ready. He sends me a video, it sounds great – but he says it has a buzz at lower frequencies and he thinks its the speaker. He tried to get it out but couldn’t – one of the studs is stripped and the board would have to be cut to be removed, so I may need a new speaker. I let him know I can handle that during my cabinet refresh and go pick it up.

I bring it home and fire it up.

I really like it! My son isn’t as impressed, but concedes that phone recordings aren’t the best. I can hear a little something going on at the low end but not much, certainly doesn’t sound horrible – but if Seth noticed it then something is off. And both he and my son are in the “get a better speaker” camp. So I decide to commence speaker research and general cleanup.

First step is taking the electronics out. 4 screws later and that’s done. The 6 digit number on the speaker decodes as being made by Rola in the 35th week of 1958, which would put this in the first year of production for the amp. 1958 was a good year.

I’m able to negotiate the stripped mounting bolt and get the speaker out. But the mounting board is another story, it won’t clear the mounting blocks at the back of the cabinet, pretty funny. These were not built for the long haul!

This gives me my first good look at the speaker. It’s dusty but appears to be intact – there is a small hole at about 8 o’clock in the photo on the left but no tears. The hole shouldn’t be affecting the sound so the low frequency buzz may have been a result of the loose mounting stud – any of the speaker, mounting board or metal screen could have been vibrating. So I’ll re-mount it and see how it sounds.

Back to the speaker board. You can see the problem below left, apparently the mounting blocks were assembled after the board was screwed in! At this point I was trying to save this piece if possible, but after trying every possible way to skootch it out I cut away a portion of the board to allow it to clear the blocks.

Upon further review this piece is nasty and will be replaced. The cutout for the speaker is pretty ragged and also seems small, will open it up a little on the new piece.

Apparently the real secret to “vintage tone” is masonite. Wonder if this is any indicator that it was made by Danelectro? Get me the the carbon dating lab.

Going non-spec with MDF. Tough to find 1/4″ masonite these days

The speaker cloth is just gross, so that has to go too. The expanded metal grill is hilarious but a little rusty, will need to be cleaned up and painted.

At this point I’m undecided about the cabinet. It’s pretty rough, the covering is ratty, and the colors seem pretty blah. It’s just a box, would take about 10 minutes to make a new one. I had this same quandry with my Premier amp, the covering was torn up in several places so I was sure I was going to end up re-covering it, but after I cleaned it up and re-glued all the loose flaps it actually looked pretty good. So I grab the Simple Green and have at it.

After a few rounds it starts to look a lot better – good news because it’s fun to preserve as much of the history as you can, and leaving the cabinet intact is a big piece of the story.

And this makes the plan of attack clear: new speaker board, grill cloth, black leather handle and emblem. Yes, there is some crazy person making reproductions of the Airline emblem. Orders placed.

While waiting I get the grill cleaned up and spray painted, and glue down all the loose flaps with fish glue.

The new grill cloth and handle arrived from MojoTone. Both look good, but the handle is so new and stiff that I give the old handle another look. The hold-downs are pretty rusty but I run them over to the wire wheel and they clean up really well. Then I apply a pretty good dose of Nokona glove conditioner to the leather handle and let it soak in for a bit.

The handle came back nicely – it’s made of several layers of leather and while the outer ones have some cracks the inside layers seem to be in good shape. Will keep the new one as a backup but the original goes back on.

Now we’re down to reassembly, which would seem straight forward except that I wanted to center the grill in the opening and that meant changing some of the original mounting holes for the speaker board. Then I was able to get the grill stapled down, the grill cloth cut and stapled on, and the cabinet back together.

So now it’s down to finishing touches. Thanks to Gary at Banana Guitars we can finish this in style and with merch!