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Bijou All Tube Futterman Headphone Amplifier - Page 101

post #1501 of 3981
10/4/08 at 10:15pm
finished casing up my work in progress this morning and flogged it all day. just finished listening to...





partnered with the HD650, the best bass i've ever heard. Amphead was also right, the sound is huge. more to come... i've gotta get back to the tunes.

btw, i found out that C5 lytic carries some voltage after being powered down for 3 days. while trying to adjust the height of the boards higher (to better ventilate via the vent holes directly underneath), my crescent wrench slipped underneath C5 and out shot a blue spark - i didn't feel anything, other than entirely stupid. feel free to lecture me.
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post #1502 of 3981
10/5/08 at 1:55am
LOL. I can't tell you how many times . . .
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post #1503 of 3981
10/5/08 at 2:31am
Quote:
Originally Posted by runeight View Post
LOL. I can't tell you how many times . . .
you mean, how many times this has happened to you?
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post #1504 of 3981
10/5/08 at 3:34am
Yes, I'm afraid so. All those years doing experimental physics.
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post #1505 of 3981
10/5/08 at 10:28am
thanks - my fragile ego has been put at ease.

i've had a couple of hours with the K701 pairing, no NFB. power doesn't seem to be an issue. in fact, dynamically speaking, it easily bests the Cayin HA-1A i owned for the better part of a year, injecting a greater sense of energy and life. this is fast sounding pairing and can really groove. i can't wait to hear the K701 balanced.
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post #1506 of 3981
10/5/08 at 10:37am
Quote:
Originally Posted by Ferrari View Post
Alex (runeight) and I are talking about increasing the quiescent current in the input/phase splitter stages of the Bijou in order to get a better operating point for tubes like 6N30-DR and NOT over PS tweak.
I'm willing to help test this for you. I have several extra boards I can use if needed (as opposed to modding my existing build).
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post #1507 of 3981
10/6/08 at 12:34am
Finally I finished my Bijou (ok, casework and some caps rolling ... ) and it sounds really great!
Thanks Alex and all prototypers for doing this amp. My DV332 must start looking for another place.
I still have problem with PS (EZ81). When I switch on the amp PS provides 275 (trimmer close) VDC, then after a few minutes it goes to ~242/246 VDC. R7 reads 248v and R8 - 300v.
I don't have the LED installed.
It is bad EZ81 or something else?
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post #1508 of 3981
10/6/08 at 12:50am
You're welcome Miky. You're not the first Bijou builder to retire a DV because of it.

There is definitely something amiss in the amount of current being drawn by the amp boards. The two voltages say 78mA. This is extremely high.

What is the heater voltage on the tubes?
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post #1509 of 3981
10/6/08 at 2:13am
Quote:
Originally Posted by fishski13 View Post
thanks - my fragile ego has been put at ease.
No, I wasn't making fun of you. I've just been zapped so many times. It was easy for me to put myself in your shoes.

But, the interior of the PS is still dangerous so please be careful.
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post #1510 of 3981
10/6/08 at 2:32am
copy.

any power-up/down recommendations? as a general rule, i make sure my phones are not plugged in on power-on, but will often leave them plugged in when powering down. i will do some DC off-set measurements tomorrow when i fine tune the PS - 50 hrs of continuous operation.
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post #1511 of 3981
10/6/08 at 3:18am
Quote:
Originally Posted by Ferrari View Post
Yikes… the casework of this amp give me some serious headache!
Nice work, Ferrari. I can't quite make it out, but is the casework complete? I can't tell if the headphone jack is just a hole or not. :P Either way, the blue diffuse backlight coming out of the headphone jack is quite nice.

What transformer are you using? I probably missed it. I think it's time I finally build my Bijou in the next few months, and I need to get up to speed on all the tweaks.
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post #1512 of 3981
10/6/08 at 5:50am
Holland welcome to the "dark" side of amp building. ;-)

Pabbi, I will mount the amp boards tomorrow, after the white line fever recedes. You should be seeing pics of the progress soon as well. I know I know the suspense is unbearable, and it feels like watching molasses flow uphill. ;-)
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post #1513 of 3981
10/6/08 at 10:55am
Well, if you feel the need to punch some vent holes prior to dropping in the boards, feel free. And, I was thinking this weekend how much better the Bijou was going to sound than the current rig... well, at least until the BH gets back, running xf2. That will be a shootout.

Sounds like the end is in sight.
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post #1514 of 3981
10/6/08 at 12:22pm
Quote:
Originally Posted by fishski13 View Post
btw, i found out that C5 lytic carries some voltage after being powered down for 3 days.
my favorite way to find this out is when you have a couple wires coming from say an unregulated PSU with a large cap and you measure out the two wires to be the same length and then cut them with some cutters... nice big flash and pop just a few inches away from your hands
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post #1515 of 3981
10/6/08 at 12:44pm
Yes, done that too. The current was so high the cutters wound up with two notches in the blades where the wires were cut and very tiny blobs of melted metal flew out and stuck into the plastic of my glasses.
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