Nobelium - tube bass preamp project

Tassieviking said:
If you have a faceplate you can mark the slots on the box and then just cut a larger square hole in the box, the faceplate will cover the hole and you will only see the slots in the faceplate.
You can always use your own slide switch for the ground lift if you want, or just carefully file the hole into a slot, its your pedal so just modify away all you like.
Click to expand...
Thanks Tassie. We think alike.

I considered the faceplate thing you suggested, but worry that the slotted plastic faceplate over a big hole with hot valves underneath might not hold up. Probably worrying for nothing, I'll think about that some more.

I've just ordered some cheap 3mm cutters for my trim router, I'll try slotting the aluminium over the existing holes first and see what that leaves me with.

Very minor issues. For my next one (!!?) I'll drill the enclosure myself. Pray for me..
 
I don't think that the fascia panel is made of plastic,at least they didn't use to be.
The slots are not really needed for ventilation, they are there to show off the tubes as far as I know.
I order my boxes from Tayda since they will machine all the slots and holes and then paint the enclosure, they look great from Tayda.
If Tayda is not an option for you then maybe someone in your country can machine and paint the enclosure for you, the drill and paint files are posted on the C2CE website and many people can do the job for you.
Cheers
Mick
 
Hellboy said:
Thanks Tassie. We think alike.

I considered the faceplate thing you suggested, but worry that the slotted plastic faceplate over a big hole with hot valves underneath might not hold up. Probably worrying for nothing, I'll think about that some more.

I've just ordered some cheap 3mm cutters for my trim router, I'll try slotting the aluminium over the existing holes first and see what that leaves me with.

Very minor issues. For my next one (!!?) I'll drill the enclosure myself. Pray for me..
Click to expand...
The faceplate is made of FR-4 (fiberglass) with layers of copper on each side under the solder mask. It will hold up to heat just fine.
 
That's good to know, thanks.
No excuses left, I'll get building.

I have some minor mods in mind. I like the bypass toggles vigilante puts on the pre-made preamps, and will mount the XLR volume as a panel-mounted pot somewhere out of the way.

I also like the idea of an adjustable HPF.
I see Tassie has done some thinking on this. For me, I think a three-position HPF switch in the place of the current two-position switch with the middle position swapping in a different R18 value for a 45Hz roll off at 6db/octave.

Trying not to mess up the lovely facia too badly..
 
The HPF switch is switching the capacitor in and out which is why I used an ON-OFF-ON switch for the HPF to make it a 2 frequency HPF.
If you want to change R18 then I would place a 250k pot in series with R18 to make it a variable HPF, I have never tried this but I guess it should work.
If you try it then please let us know how it went.
 
Back at the beginning of the thread, the power output was listed at low 500ma and that a 600ma was recommended. Now that there’s more use, is this still the recommendation? Looking to buy one to replace my one spot daisy chain.
 
I’ve made quite a few and 553mA is the lowest value I can quickly find. The tubes I use have a slightly higher current requirement (5814A’s).
When cold the current starts very briefly at near 600mA before dropping quickly down to around 565mA and then slowly drops a further 10-20mA over the next 10min or so.
So yes. 600mA is best in my view.
 
SamuelG said:
I’ve made quite a few and 553mA is the lowest value I can quickly find. The tubes I use have a slightly higher current requirement (5814A’s).
When cold the current starts very briefly at near 600mA before dropping quickly down to around 565mA and then slowly drops a further 10-20mA over the next 10min or so.
So yes. 600mA is best in my view.
Click to expand...
Where do you get your 5814A tubes from ?
Is it a local Au dealer ??
 
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