6B4G - The Resurrection Shuffle

Dave the bass · Post by **Dave the bass** » Tue Oct 24, 2017 7:09 pm

Cressy Snr wrote: ↑Tue Oct 24, 2017 2:56 pm
After that he gave me a hand bell and sent me on my way.

I LOL'd!

Cressy Snr · Post by **Cressy Snr** » Tue Oct 24, 2017 8:59 pm

Ray P · Post by **Ray P** » Wed Oct 25, 2017 6:23 am

Cressy Snr wrote: ↑Fri Oct 13, 2017 4:19 pm

My gran had the above, 1958 KB Royal Star telly in the 60s when I was very young.

Looks like Whicker's World is on...

Cressy Snr · Post by **Cressy Snr** » Thu Oct 26, 2017 10:47 pm

Got a bit done today.
Have nearly finished wiring in all the mains stuff and the filament transformers for the 2A3s.
Busbars are in for the grounding scheme. Mains will be tested tomorrow once the wiring is done.
In the case of the filament transformers, I'm reusing 12 year old bits so a few wires have had to be jointed to extend them, and the joints sealed with heatshrink sleeving.
OPTs are next on the list to be wired in, plus the speaker outlets. Then the power supply and finally the audio circuits.

May be done and playing by next weekend. There's no rush.

Cressy Snr · Post by **Cressy Snr** » Sat Oct 28, 2017 9:02 pm

Got on nicely today and the result of that effort is a full set of heaters and filaments.

Thermal delay relay switches in the rectifier heater winding after a delay of 45 seconds.
This gives the heaters and filaments of the audio circuit valves nearly a minute to warm up, then at the appointed time, the relay contacts close and HT should come up nice and smooth, rising to the design value with no overshoot.

IslandPink · Post by **IslandPink** » Sat Oct 28, 2017 9:09 pm

Phwoaar !

Ali Tait · Post by **Ali Tait** » Sat Oct 28, 2017 9:17 pm

Larverly Steve!

Dave the bass · Post by **Dave the bass** » Sat Oct 28, 2017 9:57 pm

Halt the project!

That Artex has got to go before any more amp building.

IslandPink · Post by **IslandPink** » Sat Oct 28, 2017 10:05 pm

Oof ! Yes - good call there Dave .

Cressy Snr · Post by **Cressy Snr** » Sat Oct 28, 2017 10:10 pm

Dave the bass wrote: ↑Sat Oct 28, 2017 9:57 pm Halt the project!

That Artex has got to go before any more amp building.

It's only the hobby room.

Bare floorboards too.
A veritable indoor shed.

Cressy Snr · Post by **Cressy Snr** » Mon Oct 30, 2017 3:53 pm

Amp is now wired up, working and on soak test:

No transformer snubber networks yet, apart from the choke.
Mains transformer and choke are both rubber mounted to minimise mechanical hum.
Very little heater hum from the output stage. Voltages stay rock steady courtesy of a proper choke input power supply.

Cressy Snr · Post by **Cressy Snr** » Mon Oct 30, 2017 5:58 pm

Trialling in the system now:

Lovely tone squire.
A bit of hum when things are quiet. I think the heater centre tap for the inputs and drivers heating arrangement needs moving, but apart from that, things are sounding pretty sweet. The JJ 2A3-40 are nice valves.

But Jesus, it's BIG.

jack · Post by **jack** » Mon Oct 30, 2017 6:12 pm

I've never said this before, but...

... shabby!

simon · Post by **simon** » Mon Oct 30, 2017 6:18 pm

Cressy Snr wrote: ↑Mon Oct 30, 2017 5:58 pm But Jesus, it's BIG.

Nah, not really

Cressy Snr · Post by **Cressy Snr** » Mon Oct 30, 2017 9:59 pm

It's big compared to my NVA A20

Got an old style teething problem, that both Simon and myself have experienced a couple of times in our amp building careers

Decided to try some rectifier rolling...bad move.
A previously nice sounding old Bentley 5U4G rectifier valve promptly flashed over at switch on, blowing the mains fuse in the IEC connector and taking out one of the solid state diodes in the hybrid bridge. Oh poo!

Never mind, more robust replacement diodes will be fitted tomorow, the base cover and feet made and the wooden end cheeks Danish oiled.
Normal service will resume shortly.

audio-talk

6B4G - The Resurrection Shuffle

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