Big-A$$ Bass Head Build

[Bigwan]

Wow this takes me back... I built a 20w Dumble clone for my brother's 30th birthday. This looks quite a bit... BIGGER!!!

[JapanAxe]

I drilled the main board the other day and have just swaged the eyelets. There are also 3 turrets, which will support the rectifier diodes and provide connection points for the incoming AC.

 

The red stickers cover the mounting holes where the standoffs will go, so that some eejit doesn't stick eyelets in them...

 

[JapanAxe]

Progress on the main board over the last 24 hours:

 

[rwillett]

On 25/07/2025 at 08:37, Bigwan said:

Wow this takes me back... I built a 20w Dumble clone for my brother's 30th birthday. This looks quite a bit... BIGGER!!!

 

Did you have a schematic for this please?

[Bigwan]

42 minutes ago, rwillett said:

 

Did you have a schematic for this please?

Schematic and chassis layout are quite freely available online if you search for Brown Note D'lite. It was a kit build.

 

A guitar playing buddy who'd been through (conservatively) £20k of amplification in 5 years at that point said it was the best amp he'd ever played so I was pretty chuffed at that...

[JapanAxe]

Main board finished(-ish). The keen-eyed will notice a change in dropping resistor in the middle of the board. I had mistakenly written 1k instead of 10k on my layout!

 

Also what I thought I were 22nF caps in my stash were actually 2.2nF, so I've had to order some more 22nF - hence the unpopulated gap next to the honking great 100uF/500V cap.

 

 

[rwillett]

22 minutes ago, Bigwan said:

Schematic and chassis layout are quite freely available online if you search for Brown Note D'lite. It was a kit build.

 

A guitar playing buddy who'd been through (conservatively) £20k of amplification in 5 years at that point said it was the best amp he'd ever played so I was pretty chuffed at that...

Thanks for this.

[JapanAxe]

More progress:

 

[JapanAxe]

State of play tonight. Most of the 'back end' connections are made, and after much cursing and struggling with inaccessible M3 fixings, the bias board is fitted. I'm not 100% happy that it's secure though and I may yet look at mounting it to the end of the chassis.

 

[JapanAxe]

More work last night and tonight:

 

- Re-installed the bias board more securely (bolts have nyloc nuts);

- Added the feeds from the PI to the 6L6 control grids, as well as the negative bias supplies (all of them  brown/blue wires);

- Connected the AC (orange) and ground (black) to the bias board;

- Installed the NFB connection and corresponding ground reference (green/black wires).

 

[JapanAxe]

Another gap occasioned by visiting family, holidays, and a load of gigs. Tonight I wired up the input socket, deep switch, and some  connections on the preamp valves.

 

[Geek99]

This is all just other-worldly - I don’t get how anyone can do this 

 

 

[itu]

Are you going to put some extra safety resistor to the output, in case the cable is disconnected? Do the connectors have suitable switches? 

[JapanAxe]

24 minutes ago, itu said:

Are you going to put some extra safety resistor to the output, in case the cable is disconnected?

Each of the output taps that I have used (4ohm and 8ohm) has a jack socket and a Speakon socket in parallel. I'll always use the Speakon socket (unless I have no other choice) and the plug locks into place on those.

 

26 minutes ago, itu said:

 Do the connectors have suitable switches? 

There is no impedance selector swith - I don't trust them!

[itu]

Sorry, I meant the load resistor, and a switch (in the jack) that chooses between the resistor load and the cab. But as you use Speakons, that's not an option. 

 

Your amp will not only sound good, but looks good, too.