Bijou Headphone Amplifier build

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davebms
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bijou

Post by davebms » Thu Oct 20, 2011 7:48 pm

Greg wrote: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:
i think you have more experience than me in diy audio :roll:
but the Cavalli Audio web site still has all the info on this amp + 2 forums
headwise and head-fi have long posts.
the boards are very good . i did a mod suggested by clive to use the C/T to elevate the heaters to reduce hum ,no advantage over the original circuit that uses 40 volt elevation
the sound is very open and clean but i use senn hd 590 phones that have a bright mid band .so for my ears it can be a bit much. the other odd thing is the input vale 6922 i normally find different brands sound very different .but in this no.. all about the same the idle currant on the 6922 is low so poss it need changing to make it work harder
best run it in first!!!
dave

davebms
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bijue

Post by davebms » Sun Jan 01, 2012 3:25 pm

hello all,, this http://www.ebay.co.uk/itm/ALL-TUBE-EZ80 ... 70&afsrc=1 put up by CRESSY would it power my bijue ? the bijue uses 250 volt.. and i think this thing drops 25 volt (in to out) the snag is my R CORE is 260 230 0 230 260 at o.1 amp the power supply calls for 290x2
could it b made to work ?

dave

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al newall
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Post by al newall » Sun Jan 01, 2012 4:58 pm

If your R-core is 220/230v primary like most Chinese items, and if you're mains is typically 240v+. You'll get some extra volts on the secondary anyway.
Also the ad says input 260v upwards. Might have a chance.
Much to learn there is.

davebms
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Post by davebms » Mon Jan 02, 2012 3:12 am

al newall wrote:If your R-core is 220/230v primary like most Chinese items, and if you're mains is typically 240v+. You'll get some extra volts on the secondary anyway.
Also the ad says input 260v upwards. Might have a chance.
well, my transformer is 240 and is spot on (no over volts)it does have a 230 tap that may push it up but that will up the 6.3 volts as well, as you say it will work at 260 but only get 235 out (i think ?)

dave

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Paul Barker
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Re: bijue

Post by Paul Barker » Mon Jan 02, 2012 4:40 am

davebms wrote:hello all,, this http://www.ebay.co.uk/itm/ALL-TUBE-EZ80 ... 70&afsrc=1 put up by CRESSY would it power my bijue ? the bijue uses 250 volt.. and i think this thing drops 25 volt (in to out) the snag is my R CORE is 260 230 0 230 260 at o.1 amp the power supply calls for 290x2
could it b made to work ?

dave
With a series pass reg you need at least 50v across the pass valve for quality but preferably 100. these cheap kits of parts are great value. watch resistor values they sometimes get a decimel point wrong when picking the parts. not relevent to this one.but i bought solid state kits like this everything was ok except two things. a value of resistors would be in wrong final band colour so red not orange etc. but worst problem chips were faulty. not blown but not working properly.

So see a kit lkke this as most of what you need almost correct.

In your case you better off without the reg if you dont raise supply prior to reg. at 25 for regulation you dont have a regulator at all. complete waste of effort and parts. for Steve it is no benefit. inadequate and not as good a circuit.

davebms
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Re: bijue

Post by davebms » Mon Jan 02, 2012 11:26 am

.

In your case you better off without the reg if you dont raise supply prior to reg. at 25 for regulation you dont have a regulator at all. complete waste of effort and parts. for Steve it is no benefit. inadequate and not as good a circuit.[/quote]

hello , thank for the info (im dave btw steve found it i was hopeing to use it) well ill have to stick with kit power supply, i works but the mosfets die if you go near it with the iron!!

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Paul Barker
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Re: bijue

Post by Paul Barker » Mon Jan 02, 2012 1:22 pm

davebms wrote:
Paul Barker wrote:In your case you better off without the reg if you dont raise supply prior to reg. at 25 for regulation you dont have a regulator at all. complete waste of effort and parts. for Steve it is no benefit. inadequate and not as good a circuit.
hello , thank for the info (im dave btw steve found it i was hopeing to use it) well ill have to stick with kit power supply, i works but the mosfets die if you go near it with the iron!!
Probably because the iron will short whatever voltage potential you put it on to ground. not good for the iron either.

I think these little kits are great value you couldn't buy the parts for that let alone have a pcb made. But you have to be the kind of person capable of scratch building the circuit or be happy with failure. They aren't sufficiently explained or complete (as I said before usually some wrong values are packed.). Their circuit diagrams can be chronic. And their designs are just robbed from published ones which are not necessarily state of the art today.

davebms
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Re: bijue

Post by davebms » Mon Jan 02, 2012 5:05 pm

[hello , thank for the info (im dave btw steve found it i was hopeing to use it) well ill have to stick with kit power supply, i works but the mosfets die if you go near it with the iron!![/quote]

Probably because the iron will short whatever voltage potential you put it on to ground. not good for the iron either.

hmm i wonderd what was going on (dont want to blow up me litle solder station

I think these little kits are great value you couldn't buy the parts for that let alone have a pcb made. But you have to be the kind of person capable of scratch building the circuit or be happy with failure. They aren't sufficiently explained or complete (as I said before usually some wrong values are packed.). Their circuit diagrams can be chronic. And their designs are just robbed from published ones which are not necessarily state of the art today.[/quote]

it was just a thought ,to poss get a better power supply than its got (with no mosfets) thank for your help

dave

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Mike H
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Post by Mike H » Tue Jan 03, 2012 12:23 pm

Aye power MOSFET's can be such sensitive creatures, they may take X hundred Volts and pass Y Amperes, but you try touching the gate pin after shuffling across the carpet, say.

Ergo I adopt a safety procedure when handling, identify the source & gate pins, put one finger on source then a second onto gate. Then it's got a good chance of surviving just being held. Also work on it while it's lying on its conductive bag will help.

In working situ, have a high value resistor between source & gate to discharge the gate when the circuit is turned off, better yet a Zener diode with a theshold Voltage rating equivalent to or slightly less than the maximum safe gate Voltage.
 
I never make the same mistake twice. Instead I prefer to fill my day with a variety of different mistakes

Max N
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Post by Max N » Wed Jan 25, 2012 7:48 am

Did any of you find a nice chassis to house your Bijous?
Jack and I are going to be building one, so a nice chassis will make things a lot easier.
Thanks

davebms
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Post by davebms » Fri Jan 27, 2012 8:27 pm

Max N wrote:Did any of you find a nice chassis to house your Bijous?
Jack and I are going to be building one, so a nice chassis will make things a lot easier.
Thanks
in my case NO (im not sure how many builders there are ?) Ive looked at a large Hammond case ,with a view to using it upside down and make a top plate .i have the ez81 air wired ,and the tall components on the underside of the boards, so valves can stick up.. i am now thinking of two boxes so it will fit on a shelf .if you find a good option please let me now also be interested in any changes you make

dave

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Greg
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Post by Greg » Fri Jan 27, 2012 9:56 pm

Hi Max,

I've not built mine yet, but around the time Clive excommunicated himself from this forum, I had some emails with him about the build. Infuriatingly, something has happened to my email and I've lost a load of stored messages including his advise on enclosures. I've emailed him asking for a reminder but no reply up until now.

He recommended placing in a single large enclosure to space all the parts and to allow sufficient room for valves to be mounted vertically.

If my memory is right, I think Clive recommended an enclosure from
http://www.hifi2000.it/default.asp?Langid=1 and I think from the 'Pesante' range.

This will be a big box for this amp and Dave's suggestion of a two box option might be preferential.

Greg

davebms
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Post by davebms » Sat Apr 21, 2012 7:58 pm

hello all. i would to try DC heaters , the power supply uses the end of
R9 to elevate the heaters ..my thoughts are to cut the track on the pcb to put a lead onto the end of R9 .. ez81 on AC, shottley bridge, cap res cap re elevate after the first cap
the transformer has 3.15 0 3.15 x 2 at 3amp they are in parallel so 6 amps will that be ok :?:
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davebms
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Post by davebms » Sat Apr 21, 2012 8:07 pm

hello all also on the transformer i have 2.5 o 2.5 taps at 3 amps
could i try a gz30 instead of the ez81 needs different base but that's no problem (the valve wizard ) shows several ways to wire them inc Rs in the anode supplies

dave

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