Over excited about a new vintage AC 50 purchase.

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Re: Over excited about a new vintage AC 50 purchase.

Postby Somerset on Sun May 28, 2017 9:36 am

Dave, congrats on the AC50 - great amp. As you say, AC50s with serial numbers in the 5000s are from 1966 (unless something strange is up) - http://www.voxac50.org.uk/ac50_large_07.htm
Will look out for further pics.
Cheers, Nick
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Re: Over excited about a new vintage AC 50 purchase.

Postby fiveightandten on Thu Jun 01, 2017 3:31 am

pdf64 wrote:I suspect that you may have used the KONLF type, ~35mm diameter, with terminal tags rather than lead wires?
The KONAZ type diameters are smaller.
Ahhh, yes. These smaller ones were never available in the US. I remember starting a thread about this a while back and I couldn't get them. But I just looked around and Antique Electronics has them! I just ordered 4 (two for each of my AC-50 heads). Thanks! :highfive:

They must've have just started carrying them here over the last few years. But that's great to know they're available. I've had good luck with F&T caps, and I run their 32/32 can caps in the 1st stage (top mounted on the power amp chassis) on both my AC-50 heads. I'll feel better about having those in there over the CE firecracker caps. Hum hasn't been an issue with the CE 10/10, but it's always better to have the proper spec.

I ordered some new tubes as well. Recap, retube and rebias before the gig next weekend, hopefully. :mrgreen:

-Nick
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Re: Over excited about a new vintage AC 50 purchase.

Postby Dave_in_Va. on Mon Jun 05, 2017 4:31 pm

I received the amp and I've been trying to post more pics but I'm getting a "Page not found" message.

(EDIT: Must have been too many pics.)

Got it an hour ago. Still haven't unpacked the cab.

The first thing I noticed after unpacking the head was alot of flaky small bluish/turquoise particles. At first I thought they may be some ancient residue from a popped cap but up further review decided it was rat poison. It's probably old and expired but I've been very careful and have been constantly vacuuming. I believe I got it all but I haven't removed the plinth yet to look under the chassis.

The amp has been serviced at some point as there are GT EL34's installed. Even though someone has marked all four pre-amp tubes as 12AX7, there is a 12AU7 installed. The 12AX7's are Sylvania (JAN) and the AU7 is a GE (I think) marked "CBS). These tubes lead me to guess the amp was looked at in the '90's.

The pics are kind of crummy as it's raining here so I'm trying to shoot indoors with no flash. I'm going to post more pics in a bit....
Last edited by Dave_in_Va. on Mon Jun 05, 2017 4:54 pm, edited 1 time in total.
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Re: Over excited about a new vintage AC 50 purchase.

Postby Dave_in_Va. on Mon Jun 05, 2017 4:36 pm

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Re: Over excited about a new vintage AC 50 purchase.

Postby Dave_in_Va. on Mon Jun 05, 2017 4:37 pm

URL=http://s199.photobucket.com/user/kurzman/media/ac2_zpsdrksdfow.jpg.html]Image[/URL]

Image

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Re: Over excited about a new vintage AC 50 purchase.

Postby Dave_in_Va. on Mon Jun 05, 2017 4:38 pm

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Last edited by Dave_in_Va. on Mon Jun 05, 2017 4:43 pm, edited 1 time in total.
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Re: Over excited about a new vintage AC 50 purchase.

Postby Dave_in_Va. on Mon Jun 05, 2017 4:38 pm

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Re: Over excited about a new vintage AC 50 purchase.

Postby Dave_in_Va. on Mon Jun 05, 2017 4:46 pm

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Re: Over excited about a new vintage AC 50 purchase.

Postby Dave_in_Va. on Mon Jun 05, 2017 4:46 pm

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Re: Over excited about a new vintage AC 50 purchase.

Postby Dave_in_Va. on Mon Jun 05, 2017 5:19 pm

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Re: Over excited about a new vintage AC 50 purchase.

Postby Dave_in_Va. on Mon Jun 05, 2017 5:20 pm

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Re: Over excited about a new vintage AC 50 purchase.

Postby Blind Lemon Chitlin on Tue Jun 06, 2017 2:45 pm

Looks Great !!! Mostly original. You should replace all of the Hunts 25 mf caps as well as all other electrolytic caps, mainly because of the voltage issue because we do not have 110/115 vt. here in the USA any longer...more like 120 in most places.. Stick close to the original mf values, however you can go higher on voltage rating. Should the amp need some help there are many here who are JMI/V%x specialists . I am located in Georgia. Others may be closer to you. At $1500 for the complete rig, you did very well !!
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Re: Over excited about a new vintage AC 50 purchase.

Postby pdf64 on Tue Jun 06, 2017 3:18 pm

Hunts film caps are bad news :ick: ; just everything Hunts should be on the replace list.
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Re: Over excited about a new vintage AC 50 purchase.

Postby fiveightandten on Tue Jun 06, 2017 4:47 pm

+2 to the above.

I replace the Hunts electrolytics with Sprague Atoms for the most part. F&T are good for the multi section, and as mentioned above, their 16/16 are now available in the US and are perfect drop in replacements. I used a Sprague PS to replace that big red Hunts 0.05 /1500V (it's right in front of the diode bridge).

It looks to be in good shape and largely original. One screen grid resistor has been replaced. Have you fired it up?

Outside of the caps, the only thing that concerns me is the brimistor on the top of the power amp chassis. That's a heavy component, and the leads could snap from being all twisted and having it lay on its side like it is. If it were my amp, I'd likely cut it back and remount it vertically. There are also other mounting methods that are more robust. But I'm probably overly sensitive to that particular component. I bought one of my AC-50s for $400 because that part had a broken lead and the shop deemed the amp as non functional. Their tech missed the problem and they offered it to me as a broken amp, for cheap. Good for me. Bad for them.

Anyways, glad to see you got it! Enjoy!


-Nick
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Re: Over excited about a new vintage AC 50 purchase.

Postby Dave_in_Va. on Tue Jun 06, 2017 6:27 pm

Nope. I want to get it serviced before I fire it up. If it was a Fender, which I've done before I'd order the parts and do it myself, but this is a little more exotic and I'd feel better having a Vox specialist reanimate the beast.

It looks like both fiveightandten and Blind Lemon are both familiar with these. Which one of you guys want to take a crack at it? Are both of you guys set up with tech type tools or whatever? I'm ready to Fed Ex it out anytime. I have the nice packaging it came in (all bubble wrap, no plastic peanuts) and have pulled the tubes. I also have an extra batch of tubes to send along if they're needed.

Thanks guys for all of the help. Hopefully it will live again, soon.

(Edit: I use a bucking transformer for stuff like this. It usually puts out 115 - 117 volts.)

(Edit again: I used these..

http://www.mouser.com/ProductDetail/Ame ... XxjQ%3d%3d

...on some old Silvertones. I still have some. Would these be a good replacement or back up for the Brimistor?)
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