Whats on your amp workbench?

Amp tinkerers and people who aren't afraid of 700 volts or so in here....

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MikeC
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Re: Whats on your amp workbench?

Post by MikeC »

What actually is re-laminating - presuming the existing laminates are re-usable from the old transformer?
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Re: Whats on your amp workbench?

Post by RectifiedAmps »

MikeC wrote: Sun Oct 23, 2022 8:17 am What actually is re-laminating - presuming the existing laminates are re-usable from the old transformer?
Yes, the core is original but he applies a laminate to the exterior, which prevents the rusting that causes shorts between individual sheets of the core. It’s probably not necessary but it’s a nice touch and keeps the exterior of the transformer in good shape for years to come.

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Re: Whats on your amp workbench?

Post by MikeC »

So the "laminate" is like a liquid coating that hardens, like shellac or similar?
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Re: Whats on your amp workbench?

Post by RectifiedAmps »

Yeh, you see the term used for both the interleaved steel sheets of the core and the insulating coating of varnish on them, so it can be confusing.

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Re: Whats on your amp workbench?

Post by robthemac »

Damn bulky transformers.

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Re: Whats on your amp workbench?

Post by MikeC »

An early sixties JMI Vox AC30/6. The combo cab has 2 x 12" Fane speakers - I'm keen to hear how this sounds when I get it going!
I tested all the pre-amp tubes on my Avo C.T.160 valve tester - incredibly they are all serviceable and will be staying in the amp. And I think they're original. The Mullard El84 quad was another story as was the rectifier (that's a new JJ 5AR4 in the pic)...

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Re: Whats on your amp workbench?

Post by bender »

MikeC wrote: Tue Dec 06, 2022 8:11 pm An early sixties JMI Vox AC30/6. The combo cab has 2 x 12" Fane speakers - I'm keen to hear how this sounds when I get it going!
I tested all the pre-amp tubes on my Avo C.T.160 valve tester - incredibly they are all serviceable and will be staying in the amp. And I think they're original. The Mullard El84 quad was another story as was the rectifier (that's a new JJ 5AR4 in the pic)...


Early 60's JMI Vox AC30.jpg
Early 60's JMI Vox AC30 #2.jpg

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Re: Whats on your amp workbench?

Post by olegmcnoleg »

What he said. Where did you find that???

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Re: Whats on your amp workbench?

Post by MikeC »

The amp's not mine unfortunately, the owner was sent my way via a recommendation.
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Re: Whats on your amp workbench?

Post by codedog »

MikeC wrote: Tue Dec 06, 2022 8:11 pm An early sixties JMI Vox AC30/6. The combo cab has 2 x 12" Fane speakers - I'm keen to hear how this sounds when I get it going!
I tested all the pre-amp tubes on my Avo C.T.160 valve tester - incredibly they are all serviceable and will be staying in the amp. And I think they're original. The Mullard El84 quad was another story as was the rectifier (that's a new JJ 5AR4 in the pic)...


Early 60's JMI Vox AC30.jpg
Early 60's JMI Vox AC30 #2.jpg
What does the "Warning" label mean? Is it for the light? When the light is on, something is wrong?

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Re: Whats on your amp workbench?

Post by MikeC »

codedog wrote: Wed Dec 07, 2022 6:52 am
MikeC wrote: Tue Dec 06, 2022 8:11 pm An early sixties JMI Vox AC30/6. The combo cab has 2 x 12" Fane speakers - I'm keen to hear how this sounds when I get it going!
I tested all the pre-amp tubes on my Avo C.T.160 valve tester - incredibly they are all serviceable and will be staying in the amp. And I think they're original. The Mullard El84 quad was another story as was the rectifier (that's a new JJ 5AR4 in the pic)...


Early 60's JMI Vox AC30.jpg
Early 60's JMI Vox AC30 #2.jpg
What does the "Warning" label mean? Is it for the light? When the light is on, something is wrong?
Didn't even notice that :oops: - perhaps warning that the amp is switched on? The bulb under the red light was blown (now replaced) but it connects to the 6.3V heaters so is simply a "power on" indicator.
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Re: Whats on your amp workbench?

Post by vinylguy »

Has that got the EF86 preamp cct as well as the top boost ECC83 cct ? I loved the Ef86 cct on the one I tried which surprised the living shit out of me as I had always written off EF86 ccts in old HiFi preamps (Leak Quad et al as a total waste of time. Which just goes to show the use of learned preconceptions I suppose.

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Re: Whats on your amp workbench?

Post by MikeC »

vinylguy wrote: Thu Dec 08, 2022 7:22 pm Has that got the EF86 preamp cct as well as the top boost ECC83 cct ? I loved the Ef86 cct on the one I tried which surprised the living shit out of me as I had always written off EF86 ccts in old HiFi preamps (Leak Quad et al as a total waste of time. Which just goes to show the use of learned preconceptions I suppose.
Nah, this one has 3 channels (each with a high & low input) labeled "Vib-Trem", "Normal" & "Brilliant". All 3 channels connect to an ECC83 (12AX7) triode stage. Each channel has it's own Volume control and there is a single global Tone control. There is a 3-position switch for the Vib-Trem Speed (a rotary, chicken head knob like the rest) & another for Vib-Trem On/Off (and a footswitch can do that too). That's it!

I also like an EF86 input stage - the sound is thick & rich. EF86s are pentodes and have lots of gain but they often exhibit microphonics especially in a combo amp. I think that's why Vox stopped using them.
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Re: Whats on your amp workbench?

Post by Slowy »

MikeC wrote: Wed Dec 07, 2022 7:03 am
codedog wrote: Wed Dec 07, 2022 6:52 am
MikeC wrote: Tue Dec 06, 2022 8:11 pm An early sixties JMI Vox AC30/6. The combo cab has 2 x 12" Fane speakers - I'm keen to hear how this sounds when I get it going!
I tested all the pre-amp tubes on my Avo C.T.160 valve tester - incredibly they are all serviceable and will be staying in the amp. And I think they're original. The Mullard El84 quad was another story as was the rectifier (that's a new JJ 5AR4 in the pic)...


Early 60's JMI Vox AC30.jpg
Early 60's JMI Vox AC30 #2.jpg
What does the "Warning" label mean? Is it for the light? When the light is on, something is wrong?
Didn't even notice that :oops: - perhaps warning that the amp is switched on? The bulb under the red light was blown (now replaced) but it connects to the 6.3V heaters so is simply a "power on" indicator.
Old AC30's would occasionally get inspired to have a go at killing their owners. Maybe JMI realised this and having it powered up was considered worthy of a warning. :D
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Re: Whats on your amp workbench?

Post by Bg »

Staying on my workbench for the time being…. Power transformer went a few years back and as luck would have it, Ryan was selling one.

Never got around to changing it, it’s my 36 water (1974x x2).
Always sounded great but loud. Tmb channel and vol/tone channel. I got fuzziebro to work his magic in it hence the load of old stock parts. Going to remove the cobwebs and rebuild as an 18watter
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