Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Bijou All Tube Futterman Headphone Amplifier
New Posts  All Forums:Forum Nav:

Bijou All Tube Futterman Headphone Amplifier - Page 20

post #286 of 3981
4/2/08 at 12:48am
Quote:
Originally Posted by ericj View Post
How much power are these LEDs likely to draw?

Call me a cheap bastard, but, wouldn't it be possible to just hook up a voltage doubler and full wave bridge rectifier to the 6.3v heater supply? Or just the rectifier and a bit of a capacitor.

I mean, we're talking about maybe at the outside a few hundred mA of LEDs, right?

Edit: Oh wait, you're implying that the LEDs come on when the amp is plugged in regardless of whether it's turned on?
Oh, I thought the second transformer would be hanging off of the IEC just like the main transformer is...lol... I guess it could also mean that the lights come on when the switch comes on. So many options!

DIY rocks!

The LEDs, I think, would definitely take that much power. I know a few of the blue ones at superbrightleds are around 20ma, and deliciously bright.

Anyway, can't wait to see it, amphead. Sounds like it's gonna be special!
Reply
post #287 of 3981
4/2/08 at 1:32am
Quote:
Originally Posted by bhjazz View Post
The LEDs, I think, would definitely take that much power. I know a few of the blue ones at superbrightleds are around 20ma, and deliciously bright.
20ma is the *maximum current they handle. They could perform well with a lot less, and have a longer lifespan.

Of course, while we're talking about brightness, for the sake of clarity for lurkers - because all of us already understand this - it's important to pay attention to the fact that the minicandelas rating is a rating of how bright of a dot your lamp can put on the wall. LEDs generally have a reflector around the emitter. As the viewing angle afforded by the reflector shrinks, the MCD rating increases.

Thus, my 22,000mcd blue LEDs are indeed eye-stabbingly bright, even at half their rated current, but with their 6-degree viewing angle, seriously don't illuminate a large area.
Reply
post #288 of 3981
4/2/08 at 3:01am
The removal of my 300ma rated 12vdc radio shack box transformer, is due to poor construction. It runs warm with just the leds in the power switch. The toroid that I found is small about 3.5 inches across and admittedly extreme over kill for running my leds, however I don't mind over-rating for that application. Its donut shape will be easy to mount. As far as my leds go, the power button led is on anytime the iec is plugged in, and the 4 leds under my lucite(not lexan) front panel will come on when the power button is energized.
Reply
post #289 of 3981
4/2/08 at 1:16pm
I'm not going to have any LED's in mine, but I may be trying to squeeze in another xformer and PS for an Alien Dac and the optivol kit someday.
I don't even have the LED for the original amp installed
Reply
post #290 of 3981
4/2/08 at 6:36pm
Quote:
Originally Posted by ericj View Post
for the sake of clarity
Exemplary description. Bravo!

/gloved golf claps

And knowing this information certainly makes it easier to calculate other resistor values that can extend the life of them. As opposed to being stuck with one value...that gives you one lighting option.
Reply
post #291 of 3981
4/2/08 at 9:18pm
Quote:
Originally Posted by da_burl View Post
I'm not going to have any LED's in mine, but I may be trying to squeeze in another xformer and PS for an Alien Dac and the optivol kit someday.
I don't even have the LED for the original amp installed
I have the LEDs on the amp boards. I need to go back in and increase RLED again because i want their light to be less prominant.

I need to set up a tripod or something so i can do low-light digital photography without streaking and show you all how well my bijou glows in the dark with 6n1p-ev + 6n6p.
Reply
post #292 of 3981
4/2/08 at 11:24pm
Low light photography should look awesome with your amp. ;-)

So the lucite panel was drilled for 4 instead of 3 rails on the right and left, and I'm cutting the aluminum tubing pieces to size. Edit: I went back to 3 rails L/R because 4 rails looked out of proportion.
Reply
post #293 of 3981
4/3/08 at 6:43am
is it possible to use 2 seperate transformers? ie. 1 for the 260V and 1 for 6.3V?

I have problems sourcing for the 370DX or its equivalent here in singapore. Import will be my last resort as the shipping kills.
Reply
post #294 of 3981
4/3/08 at 8:07am
hi cloud. this is no problem. just remember that the 260V is really 260-0-260 which is the same as 520VCT.
Reply
post #295 of 3981
4/3/08 at 4:51pm
Cloud, if it's difficult to source a transformer with 260-0-260 secondary, you can go alternatively for 250-0-250 secondary.
I noticed that transformers with 250-0-250 secondary are generally easier to source, at least in Europe.

For my proto, I have used this (maybe a bit oversized) 250-0-250 secondary transformer with excellent results.
The PS is set at 240V of course.


Reply
post #296 of 3981
4/3/08 at 10:34pm
Gents, if you use a 250-0-250 transformer and if you have the available extra heater current, try using an EZ81/6CA4 rectifier. You can probably get 250VDC out of this combination. This tube is in current production

In fact, with all of you guys using the 6N6P for the output tubes, I'm thinking that everyone could start using the EZ81. It will drop less voltage at the higher currents drawn by the 6N6. I haven't tried this myself, but I believe it should work. The only thing that will happen is that the pass mosfet will get a bit hotter.
Reply
post #297 of 3981
4/3/08 at 11:44pm
hmm ok. Thanks for the advice both runeight and Ferrari
Reply
post #298 of 3981
4/4/08 at 7:09am
Quote:
Originally Posted by runeight View Post
Gents, if you use a 250-0-250 transformer and if you have the available extra heater current, try using an EZ81/6CA4 rectifier. You can probably get 250VDC out of this combination. This tube is in current production

In fact, with all of you guys using the 6N6P for the output tubes, I'm thinking that everyone could start using the EZ81. It will drop less voltage at the higher currents drawn by the 6N6. I haven't tried this myself, but I believe it should work. The only thing that will happen is that the pass mosfet will get a bit hotter.
Good tip , runeight !
My 6.3V secondary is rated @6A, so I will try the EZ81/6CA4 rectifier in my next PS.
Reply
post #299 of 3981
4/4/08 at 7:23am
Finished installing the guard railing/lucite panel on the top of the amp. It has 3/16 inch thick aluminum plate anchoring the rails in the back. I will install the toroid 12vac tomorrow, in place of that Radio Shack xformer. I have a theory that I get some high pitched buzz from a noisy alpha pot in my NFB circuit. To test this theory, I will install a quality metal film resistor across the pot connections on both amp boards, after disconnecting the pot. Probably a 100k, and then a 200k metal film. If I still get the buzzing, at least the pot is vindicated. Edit: first I am going to solder a wire onto the body of the NFB pot and run that to star ground.
Reply
post #300 of 3981
4/5/08 at 2:56am
Soldered a wire onto the body of the NFB pot and then to star ground. No change to the buzz sound. I will try the resistors tonight and see what that does. The sound with tubes and caps burned-in is just so incredibly detailed and with some very good soundstage. Nice bass too. ;-)
Reply
New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Bijou All Tube Futterman Headphone Amplifier