Bijou All Tube Futterman Headphone Amplifier
Jan 23, 2010 at 7:43 PM Post #3,151 of 4,278
it matters.

look on the schematic, the there is a voltage divider that puts about +40vdc bias on the heater lines. This is required if you look at datasheets (although anyone doing ampheads mods is not doing this).

You could either parallel them for 7 amps (which means you will probably have too high a voltage). ot just just one (ez81 ~ 1amp, 2x 6dj8 ~ 0.6amp, 2X 6n6p ~1.6amp = 3.2amps @6.3v.

If the tranformer runs a bit hot, then parallel them (taking care of phase).
 
Jan 27, 2010 at 4:16 PM Post #3,152 of 4,278
After a break, i have decided to start again to work on the Bijou. But this thread now is loooooooooong.
I am sure not sure to know all the updates about this amp. Exept the "Amphead's Heater Mods" and "Reagl's mod" that i have found on Cavalli website.
What about the capacitors ?????? Could you do a "shorcut" for the different tests already done about values, caps, brands please ?

beerchug.gif

Olivier
 
Jan 27, 2010 at 11:29 PM Post #3,153 of 4,278
Does anyone have observations about using Grados, or other low impedence phones, with the Bijou?
 
Jan 28, 2010 at 8:06 AM Post #3,154 of 4,278
I do, but it may be controversial.

I thought it was bad with grados, didnt like the sound at all.

with high impedance phones the bijou is lovely and impressive. With low impedance i think sohaII or the CTH actually sound 'better' (subjective opinion only!)
 
Jan 28, 2010 at 8:23 AM Post #3,155 of 4,278
Quote:

Originally Posted by breizheau /img/forum/go_quote.gif
After a break, i have decided to start again to work on the Bijou. But this thread now is loooooooooong.
I am sure not sure to know all the updates about this amp. Exept the "Amphead's Heater Mods" and "Reagl's mod" that i have found on Cavalli website.
What about the capacitors ?????? Could you do a "shorcut" for the different tests already done about values, caps, brands please ?

beerchug.gif

Olivier



As mentioned earlier use this amp with 300 ohm or higher headphones. Remove the NFB resistor. Then for the large output caps use 100uf motor run oil caps bypassed with russian Ky40 1uf caps. Both caps are found on ebay for cheap, sound is hugely improved over using electrolytic caps.
 
Jan 28, 2010 at 12:49 PM Post #3,157 of 4,278
why?

00ma @300v over 4 tubes = ~ 25 per tube = something like an EL84 (which would want a bit more current.


not a bijou anymore.
 
Jan 28, 2010 at 3:23 PM Post #3,159 of 4,278
why do you need 100ma?

100ma @ 300 v = 30watts?

sure your calcs are correct?

6dj8 typically run 1-10ma. are you running many?
 
Jan 28, 2010 at 5:05 PM Post #3,160 of 4,278
Quote:

Originally Posted by regal /img/forum/go_quote.gif
As mentioned earlier use this amp with 300 ohm or higher headphones. Remove the NFB resistor. Then for the large output caps use 100uf motor run oil caps bypassed with russian Ky40 1uf caps. Both caps are found on ebay for cheap, sound is hugely improved over using electrolytic caps.


Thx. I'll do ASAP. I still have to find time to work on it.
confused_face.gif
 
Jan 28, 2010 at 5:29 PM Post #3,161 of 4,278
Quote:

Originally Posted by adamus /img/forum/go_quote.gif
I do, but it may be controversial.

I thought it was bad with grados, didnt like the sound at all.

with high impedance phones the bijou is lovely and impressive. With low impedance i think sohaII or the CTH actually sound 'better' (subjective opinion only!)



I very much agree. I think my HF-2s sound better out of my iPod than my Bijou. I also agree about the CTH. Just built mine and it drives them quite well.
 
Jan 30, 2010 at 11:53 AM Post #3,162 of 4,278
Quote:

Originally Posted by mugdecoffee /img/forum/go_quote.gif
I very much agree. I think my HF-2s sound better out of my iPod than my Bijou. I also agree about the CTH. Just built mine and it drives them quite well.


I agree also, The Bijou was my dream amp when my facorite headphones were Sextetts (600 ohm) and Senns (300 ohms), then I heard Grados for the first time and fell in love, but the Bijou just wasn't a good match for them. I built a SOHA II with a high tail current mod and it does a great job with Grados.
 
Jan 30, 2010 at 1:49 PM Post #3,163 of 4,278
Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif
Does anyone have observations about using Grados, or other low impedence phones, with the Bijou?


HD650's (300 ohms) sing beautifully with my Bijou, K701's (62 ohms) are, at best, ordinary. As noted by regal, the latter work better on the SOHA II but don't capture the magic of the Senns, at least not to my ears.
 
Jan 30, 2010 at 10:46 PM Post #3,164 of 4,278
Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif
Ok, caps packaged for all who gave me an address - James, Randy, Husky - need mailing info.

Again, just donate the $$$ directly to Head-fi.

Still over 100 left...
beerchug.gif



Pabbi1.

Just reading through the thread and came across this.

Do you have any of these caps left???
 
Jan 30, 2010 at 11:59 PM Post #3,165 of 4,278
Quote:

Originally Posted by rolotube /img/forum/go_quote.gif
HD650's (300 ohms) sing beautifully with my Bijou, K701's (62 ohms) are, at best, ordinary. As noted by regal, the latter work better on the SOHA II but don't capture the magic of the Senns, at least not to my ears.


Mine too... hd600, hd650 and hd800.

Quote:

Originally Posted by UKToecutter /img/forum/go_quote.gif
Pabbi1.

Just reading through the thread and came across this.
Do you have any of these caps left???



I do indeed - just ping me with an address.
 

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