Picked up a 1963 AC30/6 chassis restoration project…

[Jalmeida]

Hey guys,

I just picked up an orphaned chassis of a 1963 Vox AC30/6 normal. Amp was supposedly in working condition and has original Transformers and most of the original capacitors. It has had some botched wiring repairs and component replacements over the years that I intend to correct as well as replace the electrolytics.

On my list is:
1. Thoroughly clean chassis and sockets
2. Replace electrolytics
3. Install Top Boost Module
4. Fix janky repairs/wiring
5. Acquire or build a period correct cabinet.
6. Convert to modern 115VAC
7. Replace cathode resistor to 82R

That said, any of the brain trust have any other suggestions on things to address??

[Greenwichpaul]

This sounds great. Jealous. Subscribed.

You have probably seen but RG Keen has some build suggestions:
http://www.geofex.com/Article_Folders/voxamp/voxcab.htm
There might well be something useful on the 18 watt site too. I'll edit if I find.

Here is a source for Top boost conversions. I have bought a few bits from this seller, he's great (but grumpy), and has had repro chassis and other parts:
https://www.ebay.co.uk/itm/266743396470?itmmeta=01HVM7TPHY8WJBBA6HP4Q2N44R&hash=item3e1b253876:g:KaEAAOSwfYVh3Tuf

[Jalmeida]

This sounds great. Jealous. Subscribed.

You have probably seen but RG Keen has some build suggestions:
http://www.geofex.com/Article_Folders/voxamp/voxcab.htm
There might well be something useful on the 18 watt site too. I'll edit if I find.

Here is a source for Top boost conversions. I have bought a few bits from this seller, he's great (but grumpy), and has had repro chassis and other parts:
https://www.ebay.co.uk/itm/266743396470?itmmeta=01HVM7TPHY8WJBBA6HP4Q2N44R&hash=item3e1b253876:g:KaEAAOSwfYVh3Tuf

I actually have that kit on the way already. He did a top job on that kit.

I will study that link you shared. Thanks!

[Jalmeida]

Interesting…At some point somebody converted the heaters to DC with this Radio Spares rectifier. Also no doubt in the attempt to quiet the likely noisy amp the changed the reservoir cap from 16/16uf to 50/50uf. Also the installed a humdinger pot(oddly.) Not sure if I should attempt to reverse the DC heater mod or not. It is a bit haphazard in execution.

[sluckey]

On my list is:
1. Thoroughly clean chassis and sockets
2. Replace electrolytics
3. Install Top Boost Module
4. Fix janky repairs/wiring
5. Acquire or build a period correct cabinet.
6. Convert to modern 115VAC
7. Replace cathode resistor to 82R

That said, any of the brain trust have any other suggestions on things to address??

Put at the top of that list... Evaluate the amp before you do anything to it. Plug it in and see if it makes a joyful noise. If not, fix anything that is broken. Then proceed with your punch list.

[Jalmeida]

On my list is:
1. Thoroughly clean chassis and sockets
2. Replace electrolytics
3. Install Top Boost Module
4. Fix janky repairs/wiring
5. Acquire or build a period correct cabinet.
6. Convert to modern 115VAC
7. Replace cathode resistor to 82R

That said, any of the brain trust have any other suggestions on things to address??

Put at the top of that list... Evaluate the amp before you do anything to it. Plug it in and see if it makes a joyful noise. If not, fix anything that is broken. Then proceed with your punch list.

In general this is awesome advise. And thank you. Unfortunately I must to do items 6 and 4 before I do this. It’s still Euro wired. And some sketchy wire repairs has to be resolved before I dare do this and smoke something.

[sluckey]

Contact forum member "Yeatzee" He has recently restored two AC-30s and may have some leads to help find a correct transformer.

Look at the playlist.

[Jalmeida]

Contact forum member "Yeatzee" He has recently restored two AC-30s and may have some leads to help find a correct transformer.

Look at the playlist.

Thanks. I have built and if I have to buy a replacement, I know which direction I would lean. I am just not sure if there were any benefits to rewind an existing as opposed to replace. This PT being from a Stolec Or Dallas era diode rectified AC30 May have good iron and bobbin as a starting point. Some of the manufacturers now use a lower grade metal in the transformer laminations compared to vintage. And more specifically I just am not sure if that matters for a power transformer as much.

[Jalmeida]

Well, got the amp up and running. It needs a bit more work.

Somebody had replaced the original Albion Power Transformer with a Dallas/Arbiter era AC30 PT. Not a horrible way to go seeing the weird/obsolete El lamination works and no metal work is needed. However, the Dallas era amps used Diode rectification. This means no 5V rectifier taps. So I sent off to Heyboer for them to add 5v taps and they did. However the pink center tap wire that I foolishly presumed was for the HT, was for the heater. The HT on the Dallas amps do not have center tap. So instead of sending off again for a full teardown and rewind I added 2 1N4005 so this amp is now hybrid rectified. So I still get sag for half the wave. Anyways, because this amp came as an orphaned chassis, I built a 1963 spec smooth AC30 cabinet to house the amp and added a Topboost back panel kit.


Some sloppy twinkles of the orange Rickenbacker through the 1963 AC30 Topboost. The amp is a bit noisy. These were noisy, however I believe I have some more to tackle to quiet this one down. I have been playing it as is to run it through it's paces to shake out problems and go from here. As a baseline, the amp does sound great. Just need it to have a bit less line noise. This amp does have a Humdinger pot adjusted to balanced on the DMM, but may need a bit more tweaks there. Maybe some ground cleaning. Instead of tearing this amp down and rebuilding fully I decided I wanted a baseline of get it running first and then go from there.

eature=shared

[Jalmeida]

More

[tubenit]

You did a superb job restoring that and it's a super nice cabinet.  Bravo!  Appreciate the sound clip!  It sure has that chimey Vox tone.


With respect, Tubenit

[Jalmeida]

You did a superb job restoring that and it's a super nice cabinet.  Bravo!  Appreciate the sound clip!  It sure has that chimey Vox tone.


With respect, Tubenit

Thanks alot! It has been a fun project and I am learning a bunch.

[Jalmeida]

Got the 120hz heater noise tamed finally. After getting the amp up an running I had a 120hz heater hum. Found the source being the Power Transformer has a Center tap. And this amp has a Humdinger Pot also. That created a groundloop oscillation. So floated the center tap for the heater and kept the humdinger pot. Keeping with the factory 1963 spec power Filter Capacitor values, this is actually quiet for idle. That is all for now.

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[Yeatzee]

Nicely done! I'm not even sure mine will get that clean, for whatever reason my topboost is a firebreather. My favorite amp!