#26 pre amp

[rclourenco]

Rui,
This looks superb, absolute perfection! Well done
Ale

Hi Ale,
Many thanks for words, and very important advises.
Will keep you all posted on the evolution.
Cheers.

 

[Magz]

Where do you source your chassis?

thanks!

Abe

Front Panel Express. The top was ordered in bare aluminum and I had it chromed at a local plating shop.

 

[tyo94]

Good work Rui, I like the way you manufacture. So neat and systematic. Can't wait to see the next process

 

[rclourenco]

Just to show Merlin (as promised) what can be done with a pair of Galaxy Maggiorato enclosures.
On the top of the PS unit, pw xfrm and choke, inside two 15V/50VA xfrms for Coleman's regs. Between the xfrms 8 diodes on a yet-to-be-made pcb. Several caps (big elcaps for filaments, pp for HV) will take space inside too.
The pream hosts two Tango 160H chokes and inside the filament bias Dale's fixing hardware is contact with the front panel through an alu bar. The other two L shaped alu bars are hosting the Coleman's regs and the SSHV2 (pcbs yet-to-be-made) spreading heat on the sides and the top cover. Close to the SSHV2 regs another pcb with 10 pcs 10uF pp caps
A suspended copper subchassis will host the tube sockets.

Very good Massimo, I am a fan of copper, and I like the idea for the sockets, keep us posted on the evolution.

 

[Bas Horneman]

Some photos from the main chassis (PS on another one), work around filament supply with Rod Colleman boards. Cabling is Nordost teflon covered copper.

Wow. And well thought out too.

 

[djn]

Big thanks to CoolZero for putting links to all the schematics in this thread on the first post. This is a real time saver when looking for something you saw months ago or for new people in this thread.

 

[merlin el mago]

Thank you coolzero.

 

[merlin el mago]

Great work Felipe, looking really good!
As a suggestion, you may want to consider increasing the space between individual resistors of each stack as they will get hot. Not the most efficient way to dissipate the heat by stacking them up vertically. I have them just like you buy added some metal separators between them an longer screws...
Ale

It's enough the increased space between individual resistor?

 

[mogliaa]

They will survive if running at 1A, but I'd look at those 5mm metal spacers...
Ale

 

[mogliaa]

Btw: Noise is proportional to Temperature so you want to run them as cool as you can...

 

[merlin el mago]

If I put another nut can reach 4mm, the space between resistors is 6mm, is enough?

 

[DimZ]

vgeorge uses some 90W monster dales (post 1450) ...

dont know where he got them, but you must have plenty of room for those ....

 

[merlin el mago]

They will survive if running at 1A, but I'd look at those 5mm metal spacers...
Ale

Btw: Noise is proportional to Temperature so you want to run them as cool as you can...

Ale, what about now?

Felipe

 

[andyjevans]

That's better Filipe. Looks good to me.

I've gone back to my 26 preamp with the two 156C in series and updated the power supply a bit. The hum is still there but not audible from my listening seat, just close up to the speaker. So that's proof to me that the 156C option is viable. I must say it sounds really nice with the FT-2 teflon output caps. I'm using a couple of ordinary commercial 12v DC supplies - probably switch mode I'd guess though I haven't got inside them. They sound much better than I'd expect!

 

[andyjevans]

Here's some pics. Utilitarian look!!

 

[merlin el mago]

That's better Filipe. Looks good to me.

I've gone back to my 26 preamp with the two 156C in series and updated the power supply a bit. The hum is still there but not audible from my listening seat, just close up to the speaker. So that's proof to me that the 156C option is viable. I must say it sounds really nice with the FT-2 teflon output caps. I'm using a couple of ordinary commercial 12v DC supplies - probably switch mode I'd guess though I haven't got inside them. They sound much better than I'd expect!

Thanks Andy,

Try FT-3 in place of FT-2, huge difference: I have both.

Cheers, Felipe

 

[merlin el mago]

Here's some pics. Utilitarian look!!

All our projects looks utilitarian after seen rclourenco work

 

[iko]

All our projects looks utilitarian after seen rclourenco work

+1 After seeing his work, I'm terrified to show pictures of mine!

 

[andyjevans]

Try FT-3 in place of FT-2, huge difference: I have both. Cheers, Felipe

Really? I couldn't hear any difference at all! Should I try again?

Andy

 

[merlin el mago]

If you need I send you a couple.

Felipe