[balderon]

^^ I see you took off the plastic on C1 and looks a little unhappy ....

 

[walangalam]

You got it.
 
The amp has been running for about 4 hours, I left and came back 1 1/2 hours later to the smell of burnt electronics.
 
The big cap (C1) blew.  The fuse blew, probably saving a lot of parts.
 
Tested the transformer, its fine.  Tested the PS board after removing C1, its also fine -- giving me a B+ of 255 V.
 
Next would be to see if the amp boards are damaged.
 
I got the kit from Glass Jar, so its probably just a bad electrolytic.  Now, I'm also suspecting the other 2 big caps.  I wonder why it blew????

 

[herro]

Are there any equivalent/better transformers I could use for the build before I put in my mouser order? The 270dax is ~$70 at mouser (pointless sourcing it from somewhere else as I'm doing a mouser order already, and a cheaper price + shipping would add up to the $70 anyway.). What's this toroidal one?

 

[walangalam]

its this one: http://www.antekinc.com/details.php?p=47
 
its 39.50 shipped.
 
In my stock build, it gives 250 volts just barely, with only 5 volts headroom, and with 120 volts mains.
 
If you do the regal mod, you might have to dial it down to 240volts.
 
But its a bigger transformer, so you roll the tubes you like.

 

[holland]

Antek rates their transformers differently.  Other manufacturers rate their voltage loaded.  Antek rates theirs unloaded, and as such the voltage drops below what you expect when you put the load on.  This way they can claim higher voltage at a certain VA.  The reality is it's a lower voltage, at specific current ratings.  It's more of a 235V transformer than 260V.
 
For Antek, you need to read the datasheet, and often times you need to up-spec the xformer.  That is you will need to go more current or more voltage.
 
I use the RCore, r80-36 (i think that's the part).  I have no problems with it.  You may need to spend a bit more time, checking phase on the heater windings.  I parallel'd all the windings.  It's easy to do, once you tie the center taps together, phase is simple.

 

[flao38]

what a project, well done

 

[walangalam]

Here are voltages from my Antek transformer:
 
Rating:  250v 200ma X2, 6.3V 3A X2   100VA
 
with PS only:  265VAC, 6.6VAC
with PS + Amps:  260VAC, 6.34VAC
 
So it looks like its rated correctly, at least on this unit.  And its cool to the touch too.
 
 
Quote:

Antek rates their transformers differently.  Other manufacturers rate their voltage loaded.  Antek rates theirs unloaded, and as such the voltage drops below what you expect when you put the load on.  This way they can claim higher voltage at a certain VA.  The reality is it's a lower voltage, at specific current ratings.  It's more of a 235V transformer than 260V.

 

[holland]

Perhaps they changed.
 
It also doesn't match the spec sheet for the xformer, which is odd as their other transformers matched it quite well (read the EHHA rev A thread for more recent measurements of the Antek xformers) and it matches my Antek experiences from years ago.
 
Either way, tread carefully and read the spec sheet as it pertains to Antek transformers in particular.
 
http://www.antekinc.com/pdf/AN-1T250.pdf

 
Note the unloaded voltage of 257VAC and the loaded voltage of 237VAC.  Of course the Bijou draws considerably less current than 500mA.
 
It would be great if they start to rate as other manufacturers do.  I still use them either way, and would normally upspec.  Your measurements, however, could mean a crapshoot instead of a dependable way to deal with Antek.
 
I'd measure the Antek 0532 that I'm using for my EHHA build, but I bought it about 2 years ago, so it's probably the older spec (32V unloaded, 30V loaded).

 

[herro]

What's the best way to mount tubes externally without using any screws through the top of my enclosure? Standoffs on the PCBs?

 

[balderon]

I mounted the components on the reverse side of the amp boards. Using standoffs allows the tube sockets to extend through the top panel without screws. The only concern was the MOSFET heat sinks on the PS. There is a fair amount of heat to dissipate and the PS board will heat up significantly if the heat sinks are mounted on the reverse side. Give it some thought. There are numerous ways to solve the PS heat dissipation issue without screws in the top.

 

[herro]

Yeah, I'm getting my kit tomorrow so just currently brainstorming how I'm going to achieve certain tasks. I've decided to go with the HWCHAS from Hammond, I like the look. Not sure if I want the black or natural aluminium finish for the top though. Since the bottom plate is sold separately, I'll get a bottom plate of the opposite colour from the top plate, so I can swap them if I decide, or even get the natural one anodised.
 
Mouser is fresh out, however digikey has them for ~$108 shipped to me in Canada (a bit pricey, however I do not have the tools or want to bother with finding someone to make me something similar). This does not include the bottom panel which I found from a UK dealer for $12/$20 for natural/black respectively (digikey, mouser, newark etc. had absolutely nothing without me waiting for at least two months or more). The same UK dealer also sells the HWCHAS enclosures for $82, but shipping the heavy item might be a little pricey so I contacted them for a quote.
 
Should I just go with the 270DAX then? I don't plan on doing any major modifications, but I may want to try some better tubes in the future.

 

[holland]

Quote:

 
Should I just go with the 270DAX then? I don't plan on doing any major modifications, but I may want to try some better tubes in the future.

 
Perhaps a look at the BOM will help you decide.
 

 

[pabbi1]

370DAX is a better choice, and Angela has them at a good price... not sure about shipping to your location.
 
I can recommend the 6n6p/6n1p for reasonably priced tubes, and might also look into the 6n23p-ev. In Russian tubes, always at least consider the 'ev' versions - better QC and spec compliance. And definitely socket the R2 cathode resistor so you can roll the tubes. If I had another shot at Bijou, the 6h30 would be my first stop, since I went 6n1p/6n6p... this is NOT a universal recommendation. 
 
Anyone used the 6h30DR? Just curious. 

 

[holland]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif
 
If I had another shot at Bijou, the 6h30 would be my first stop, since I went 6n1p/6n6p... this is NOT a universal recommendation. 
 
Anyone used the 6h30DR? Just curious. 

 
I don't use the DR, but I do use Sovtek 6H30 as the gain and 6N6Pi as the driver.  I like the 6H30 over the 6922 by a good margin.  It helps that the overall gain is lower too.
 

 

[regal]

Quote:

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif
 
If I had another shot at Bijou, the 6h30 would be my first stop, since I went 6n1p/6n6p... this is NOT a universal recommendation. 
 
Anyone used the 6h30DR? Just curious. 

 
I don't use the DR, but I do use Sovtek 6H30 as the gain and 6N6Pi as the driver.  I like the 6H30 over the 6922 by a good margin.  It helps that the overall gain is lower too.
 

The 6n6p is a great driver tube for this amp,  they are very undervalued in my opinion.     For the gain it would be worth trying something other than the 6DJ8 as the only ones that sound great are expensive holland tubes from the 60's and you have to buy several to find a good pair,  so I would focus on substituting those.