Bijou Headphone Amplifier build

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Paul Barker
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#46

Post by Paul Barker »

JackOfAll wrote:LOL. Don't know why, when I've been running the IXYS "fuses" at a watt sans heatsink for years without any failures, I felt the need to heatsink for 3/4 watt........ You're more likely to destroy one with static than 0.75W. Nick made me paranoid! ;)
I have killed most of my depletion mosfet's with static. According to Nick the static breaks them down then when in circuit they are finished off.

This is why I don't use them now. They are OK soundwise but for me reliability is an issue. My chokes don't mind a little static and tolerate voltage without fusing.

I am not having a pop at people who use CCS's. You use what you have to. I don't have to.
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#47

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Paul Barker
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#48

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I haven't killed any ixys. It was actually a little to3 package depletion I killed a whole batch. Maybe it was a bad batch?

I had a couple of dn2540 casualties too, just put me off.

but i found that the AE Amorphous C core Grid Chokes can withstad 1 mA of DC so they will load the VA 1/2 of a 6em7 wonderfully. (I can't measure them my Hameg bridge only goes to 200 Henry but they are easily as infinate as they need to be to crack perfection from that valve) sound better to me than a cascade of depletion mosfets and less fickle. I understand AE have stopped making them. Not on their website anyway. Core is big enough for an interstage transformer at a gain stage but not big enough for to drive an output valve via. At least I~ can't see it on their web pages. Maybe they do special order?

Like i said if you have to use a ccs it isn't the devil, but if you don't have to you are no worse off, and if you have more simplicity in your amp you are better off. If you don't mind large heavy amps that is!

When I go balanced from the dac to the output stage I will have to revisit CCS's to keep my tails long.
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#49

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Paul Barker
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#50

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Yes it's DC to power stage which is CF so low input capacitance therefore easy to drive. common cathode to cathode follower just DC couples itself. No brainer not to do it.

I have been lucky with these AE amorphous C cores, they are very large for grid chokes fortunately.
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#51

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#52

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No problems with my sound mate :wink: All direct coupled no caps no cathode resistors resistorless capless power supply. Not changing a thing. threw it together it works great, jobs a goodun.
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pre65
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#53

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Paul Barker wrote:No problems with my sound mate :wink: All direct coupled no caps no cathode resistors resistorless capless power supply. Not changing a thing. threw it together it works great, jobs a goodun.
Is that the one that fell off the pillow ?

All repaired now I hope. :)
Life is what happens to you while you're busy making other plans. John Lennon

G-Popz THE easy listening connoisseur. (Philip)
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#54

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Paul Barker
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#55

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pre65 wrote:
Paul Barker wrote:No problems with my sound mate :wink: All direct coupled no caps no cathode resistors resistorless capless power supply. Not changing a thing. threw it together it works great, jobs a goodun.
Is that the one that fell off the pillow ?

All repaired now I hope. :)
No I started again Phil. That was a great amp, this is a heavenly amp.
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#56

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JackOfAll wrote: I just cant help myself from thinking bad thoughts when I read 1mA, regardless of who's talking about 1mA.
8) 8) 8)
davebms
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#57

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[quote="JackOfAll"]My last post on the Bijou, unless you guys building it need any help getting it up and running. (Assuming the people building are still reading after the thread went off at a tangent......)

yes i am still reading!! and poss yes (depends if it fires up ok) thank you for using your amp as a test bed !! was not going to start yet, but last Friday evening i opened the box, lots off possibilities of loosing parts :roll: so i built the power supply and yes i did through away one of the insulators with the blue tape so i made a new one. i have just built both amps all as stock but with the c/t mod on the power supply . but the R CORE is on a slow boat, and i don't have a spare t/x with a centre tap
so there will be a delay !

dave
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#58

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#59 bijou

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a working bijou
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Greg
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#60

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Well done! How does it sound?

As Clive is no longer posting here, I might need to pick your brains on stuff when I get around to builting mine. I hope you don't mind :oops:
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