1960 Jet

[journeyman]

   
   
   

This Giulietti branded Jet is on its way; looks like it's had very little use and no servicing. It's at a friend's house and he says that it is running dead quiet. I guess I should probably order a new cap can from Fliptops regardless; running 61 year old filters seems a bit risky. Those red Astrons also appear to be in fine shape, but it's probably because they have not been fired up for a very long time. Whenever I see an amp from the 1960s that hasn't been played I wonder why; either it was stored and forgotten about or the owner, well, you know. Regardless, it is a nice match for my 1961 M12 with the Navy Random Flair covering.

[Hangman]

Very Nice! I'm a sucker for the Navy Random Flair.

On the 1960s amp that hasn't been played bit, its hard to say, I've known people that kept their old guitar and amp because they meant something to them. Even though they no longer played them. others just put them away and forgot about them. time moves forward and life happens when we're busy doing other things. sometimes guitars and amps get to skip a few decades.

[journeyman]

I agree, the Navy Random Flair is hard to resist. Additionally, these early Ampegs are fantastic amps and eventually they will be up in value in much the same way that Gibsons are now. What most people don't realize yet though, is that these are on par with the Fender tweeds and better made than many of the old Gibsons. My amp tech gets Gibsons through his place and fills me in on what he sees. Some are great, but many are in his words, 'a big mess' with questionable engineering. His only criticism of these early Ampegs is the way they are grounded, but he says that the operating noise is not loud enough to open what would be a real can of worms.

[journeyman]

It turns out that this Giulietti Jet is from 1958. We replaced the red Astrons and the cap can and it is running without sputtering now. As new as those red caps looked, most were leaking small amounts of voltage and the amp would start sputtering after about a half hour of operation. It seems to run with a little more 60 cycle hum than I'd like. I guess this could be addressed with more filtering, but too much filtering can make the amp stiff. I'm thinking it's a grounding issue and I don't know how to address that. Any siggestions?

[Hangman]

Its hard to say on the Hum... you mentioned 60 cycle hum, are you sure its 60cps? or is it 120?

grounding issues would make sense, there weren't always good grounding schemes in the 50s amps can you get a couple more gut shots? it would be good to see how they handle the grounding.

[journeyman]

60 cycle or 120? Good question. I spoke with my amp tech and like most, if not all early Ampegs, everything is grounded to one spot. When he builds an amp, he has about three separate grounds, and his builds are all dead quiet. I played a small bass/guitar jazz gig last night and this thing sounded wonderful; clear but very warm; just what I hoped for. The hum is not an issue at that low volume, but it would be nice to get it running a little quieter. Perhaps in a month or so I'll get it back to my amp tech and he can trace the grounding and experiment. There's a gig coming up with a drummer and a horn section so we'll see how it does cranked up a bit.

[journeyman]

The tech went through the amp again and did a couple of things which I'm very happy with. The daisychained grounding was reconfigured from one to two points, and he added a small amount of additional filtering. To counter any potential stiffness caused by the extra filtering, the amount of negative feedback was reduced. The amp runs very quiet now and sounds beautiful. After the Jensen P12Q has had some time to break in, I'll decide whether to keep it or try a ceramic, depending on how much the bass response increases.