[ujamerstand]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif Ping luvdunhill - he has a bit better solution with better impedence matching, from what I can tell - but, better hurry. Read some more about it here.

Thanks pabbi, I've seen that one, its quite interesting! But I'm not sure if I want to go into PGA solutions before I've tried out a relay based solution. On top of that, I've already placed orders for the boards from TPA already.

Perhaps another time?

ps. your caps has arrived! Thanks a million!

 

[Olli1324]

What is the current cinsumption of an amplifier board?

Also, what is the maximum current the PS board should be able to supply befoer the voltage drops below 250V?

When I connect 1 amplifier board to the PS, the voltage drops from 250V to approx 165V.

 

[adamus]

something is wrong mate.

Either mosfet gone in the PS, or a short or wrong component in the amp board,

 

[Olli1324]

Further inspection and poking around by my dad with the multimeter suggests a blown mosfet.

Gonna order some more tomorrow...

This confirms my fear/hatred of mosfets; they are so much more awkward to play with than nice resilient resisters/caps etc

 

[adamus]

typically it takes a short for the mosfet to blow, either a wriing mistake, a solder bridge somewhere, or a slip with a dmm.

 

[Olli1324]

I'll be sure to check all that before powering up with the new mosfets.

 

[DemonicAngelz]

I've decided to build a Bijou after reading this thread from start to end. I'm going to order the kit from GJA soon. But I have a question to start off with, if I'm building a balanced build, is there a recommended transformer to use? I know for the SE version, Hammond 270DAX is recommended but what about balanced? Is there the option of using only one transformer?

FYI, my mains are 230 Volts at 50 Hertz

 

[adamus]

IF you are going to the lengths of a balanced build, then go with two tranformers.

Two of the Rcores would be fine

 

[pabbi1]

My balanced worked quite well with a single Hammond 270HX, so the 370HX should be good for universal voltage, though I did have to use some 10w resistors to bring the b+ down just a bit. It has been too long since I did that to remember exactly, but the recommendation is _somewhere_ in the thread.

 

[simwells]

Got my kit now, only thing I am unsure of is the orientation of the trimpot? I'm sure it's obvious but should the actual ajustment screw line up with the indicated circle or is it the reverse?

 

[adamus]

line it up, but in reality it doesnt matter.

 

[ujamerstand]

I've read in an old post on headwize that recommended 300 series transformers over 200 series transformers for better build quality, less heat and less buzz. Has anyone tried both and reached the same conclusion? Is the 30 dollars difference here justified? btw, a1parts.ca has both 270DAX and 370DAX in stock for Canadians.

 

[adamus]

you do often read that the 200 seeries like to buzz. personally i have the Rcore which is cheap and seems perfect for the application. it also lets you use the fantastic 8416 pq tube.

 

[ujamerstand]

I've considered using the Rcore before. But, well, one of the things I want to do in my particular build is that I want to do the regal mod. Also, I want to have enough current to go around regardless of the tube type I use. This is why I wanted to use the Current multiplier power supply mod. The Rcore seems to need a choke supply, and I am not sure whether that power supply mod will be able to supply as much current as the CMPS. That, coupled with the fact that a) having a choke takes up more space, b) the Rcore listed on vt4c's audio catalog is too fat and wide for the enclosure I have in mind, c) As good as vt4c's customer service is, their shipping is a bit on the expensive side, and takes a long time to arrive; means that I am probably going to stick with Hammond transformers. But thanks for the suggestion, I think I'll go with 370DAX for the assurance of less buzz.

 

[Olli1324]

New mosfets in and all is well in the world again. Better get started on that case soon...