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Info on this vintage amp?


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Hey all, I'm hoping to find any information about my father's gibson amplifier. He bought it along with his 57 ES125T 3/4 body. Still works well. It's a GA-5 but not a Skylark, number 17253 on the control plate.

Any historical notoriety, how they're perceived today, current value, etc. Would be greatly appreciated. Not looking to sell it, just want to know more about it. 

PXL_20210320_224104826.PORTRAIT.jpg

PXL_20210320_224137217.PORTRAIT.jpg

PXL_20210320_224150806.PORTRAIT.jpg

PXL_20210320_224122633.PORTRAIT.jpg

Edited by Boingo
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I guess from what I've read this is in fact a Skylark? It doesn't say Skylark on the control panel, so that's why I thought it wasn't.  Interesting to read about the love of these little guys. I do believe I will see about getting a 3-prong cord installed. 

Any tidbits anyone else cares to share, I appreciate your time.

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It looks like a GA-5 Skylark (the two-tone version).   Produced 1954-1961.  You can figure out the date of production by looking for date codes on the transformers or maybe the speaker.  The speaker would have a code that starts with 220.  That's the manufacturer's code for Jensen.  The numbers after that indicate the date of production, one digit for the year and then two digits for the month.  It would be on the frame or the cone of the speaker. 

Maintenance should be done before you power it up.  The electrolytic caps should be replaced and the two prong AC cord should be replaced with a three prong cord and the fuse and switch should be rewired to modern wiring.  Then it can be powered up and checked out more closely.  

Looks nice!! 👍

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1 hour ago, badbluesplayer said:

It looks like a GA-5 Skylark (the two-tone version).   Produced 1954-1961.  You can figure out the date of production by looking for date codes on the transformers or maybe the speaker.  The speaker would have a code that starts with 220.  That's the manufacturer's code for Jensen.  The numbers after that indicate the date of production, one digit for the year and then two digits for the month.  It would be on the frame or the cone of the speaker. 

Maintenance should be done before you power it up.  The electrolytic caps should be replaced and the two prong AC cord should be replaced with a three prong cord and the fuse and switch should be rewired to modern wiring.  Then it can be powered up and checked out more closely.  

Looks nice!! 👍

Thanks for that great information, much appreciated.  I did take the board out to give it a look and I guess my father must have had some work done on it at some point - there's definitely some new components in there - again, I don't know anything about these components and what if anything was replaced. Definitely am going to get a 3-prong outlet put on there!

PXL_20210321_132519541.jpg

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Looks good.  It looks like there has been some work done.  The filter caps were replaced.  The work looks really nice!

The two electrolytic capacitors over to the left - the ones with cardboard covers - they should be replaced with ones of the same rating.  The one with "20-25" on it.  That's rated 20uf, 25volts.  Not sure what the other one is rated, but you can get the parts here -

https://www.amplifiedparts.com/products/capacitor-sprague-atom-aluminum-electrolytic

The one labeled 20-25 should be replaced with a 25uf, 25v cap.  25uf is close enough to 20uf and they don't make one rated exactly 20uf at that voltage.  You can figure out what the rating of the other one is and get one rated close to that.  The amp will work fine even if those caps are bad, it just will sound a little thin if they're bad.

The cord should be replaced and rewired so the black wire from the new cord goes to the tip of the switch, then run a short wire from the side of the fuse to the other side of the switch, where it looks like the brown zipcord is hooked up now.  Leave the black transformer wire on the near side of the switch and hook the black transformer wire that was disconnected from the side of the fuse and connect it to the white wire from the cord, twisting the wires together and soldering.  Connect the new green ground wire to the best grounding point you can find.  Maybe where the three newer filter caps come together.  That's a ground.  Cord here -    https://www.amplifiedparts.com/products/cord-power-18-awg-3-conductor-black-no-iec-12-feet

You can use some zip ties around the new cord where it goes thru the chassis to keep it in place, or use a strain relief or grommet to hold it.  This might work if it fits -

https://www.amplifiedparts.com/products/strain-relief-rubber-14-diameter-hole

That should do it.  Keep us posted with any more questions.  Good luck!

Edited by badbluesplayer
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  • 2 weeks later...
Posted (edited)
On 3/24/2021 at 11:54 AM, badbluesplayer said:

Keep us posted with any more questions.  Good luck!

Got the amp back from a local shop recommended by a luthier that worked on my dad's guitar. Sounds nice plinking around, gets a little gritty if turned up slightly but too much and it starts to fart out. Probably can't go past 1/3 volume at most. Is that simply a limitation of the vintage speaker?

GA-5 and ES125T 3/4 body test

Edited by Boingo
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