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Bijou All Tube Futterman Headphone Amplifier - Page 270

post #4036 of 4176

noticed that on one of my psus under load the maximum voltage i can get is ~245v  the other runs fine at 250v sharp. checked input capacitors they are fine

 

any idea what maybe causing this? can it be the transformer?

post #4037 of 4176
Quote:
Originally Posted by yiancar View Post
 

noticed that on one of my psus under load the maximum voltage i can get is ~245v  the other runs fine at 250v sharp. checked input capacitors they are fine

 

any idea what maybe causing this? can it be the transformer?

 

It might be normal and within tolerance.  Mine is like that too, but I have Regal's mod in it and running 6H30 and 6N6P tubes.  You can reduce the R in the CRCRC filter, and increase C to compensate.  On the other hand, I have thought of using a diode bridge instead and increasing R and C.

 

I think when I noticed the most drop, my rectifier tube was dropping too much, so I changed it to a fresh tube and it was happy.  That was a few years ago, haven't opened it up since.

post #4038 of 4176

got another problem again. i left the amp for quite some time on and one of the channels stop working, i feared it was the tubes so i interchanged them and still got no sound. i measured pin 1 - 2 -3 of the 6dj8 and they were all the same voltage , 184v i panicked . any idea whats causing this

post #4039 of 4176

Yiancar- Could only find the original -2007 circuit diagram. If you have 184 V on -1+2+3 then  thats the -plate- grid-cathode- all with the same high voltage. If you have swapped them around  and you still have that fault.It must be the circuit rather than  an internal S/C in the tube. You did try your MM across pins  1+2+3 just to be sure did you? If so then it sounds like the coupling caps have failed[looking at the circuit]  Thats just ONE possibility. There are more.  Check that first.

post #4040 of 4176
Quote:
Originally Posted by duncan1 View Post
 

Yiancar- Could only find the original -2007 circuit diagram. If you have 184 V on -1+2+3 then  thats the -plate- grid-cathode- all with the same high voltage. If you have swapped them around  and you still have that fault.It must be the circuit rather than  an internal S/C in the tube. You did try your MM across pins  1+2+3 just to be sure did you? If so then it sounds like the coupling caps have failed[looking at the circuit]  Thats just ONE possibility. There are more.  Check that first.

measured the the coupling caps (c3 c4) they are fine. also checked pin 1-2-3 and they are not shorted, any other thoughts?

 

also tried changing tubes. same problem

post #4041 of 4176

stupid me... cold connection on the heater pins. thanks for the idea :)

post #4042 of 4176

When my AVO VCM -tube tester went faulty till I fixed it I thought that was a temporary test   Many people have tubes that  are S/C internally its a common problem even with good make tubes. Instead of throwing then all away you could try a high voltage pulse across the S/C this sometimes "blows" the short off. You cant keep doing it as eventually it destroys the elements inside but it is always worth a try. Circuits can be seen on old tube radio repair sites. But due to high voltage can be dangerous to use.

post #4043 of 4176
Quick question, I just finished my first amp, and was looking for another project. The bijou, having PSU in kit from glassjar, seams like a good option, as I don't have to source a transformer and test for correct voltages and etc. How easy, 1-10 would you rate this build. It looks pretty easy in my opinion, but I wanna get some inout, thanks!

Correction, I would need to buy a $80 transformer, so that's put the build at around $300, would it be worth it at that point as well? I would be driving T1's. Would the Crack be a better option?
Edited by DutchGFX - 10/17/13 at 8:55pm
post #4044 of 4176
Quote:
Originally Posted by DutchGFX View Post

Quick question, I just finished my first amp, and was looking for another project. The bijou, having PSU in kit from glassjar, seams like a good option, as I don't have to source a transformer and test for correct voltages and etc. How easy, 1-10 would you rate this build. It looks pretty easy in my opinion, but I wanna get some inout, thanks!

Correction, I would need to buy a $80 transformer, so that's put the build at around $300, would it be worth it at that point as well? I would be driving T1's. Would the Crack be a better option?

 

I would lean towards the CRACK - it is better documented and the fact that Bottlehead does all the casework is pretty attractive.

Plus the CRACK is point to point so you can start to learn how to do that and liberate yourself from the slavery of stuffing a PCB of another person's design. Building your own point-to-point amp is a very rewarding experience. 

post #4045 of 4176

I second nikongod in recommending the Crack. Although I've not built or heard one, the build looks to be easy and from what I've read, should sound

excellent with your high-impedence T1's. Tyll over at Inner Fidelity documented his Crack build on video. Check it out. I have built a Bottlehead Eros

phono amp, and the documentation/instructions (on CD) are excellent.

 

As a personal aside, my first kit build (many moons ago) was a Dynaco PAT-4 preamp. Even though it used circuit boards, they were already assembled/

tested, so it was essentially a point-to-point build. It had very detailed, step-by-step build instructions (like the Eros), that I like to call 'electronic kit building

for the complete idiot' because it was my first, and it worked first try. :wink_face: The trick is is go slowly; read each instruction twice, solder once.

post #4046 of 4176

Three-fer.  Start with a Crack.  My own comments after hearing one a few years back:

 

"...Dan Schmalle and Queen Eileen: The Crack is amazing.  I'm sure someone would have tackled me at the door, but I really wanted to just run out the door with it and keep it for my own.  I'm sure your mega tape system had a lot to do with the great sounds I was hearing.  Never mind.  The Crack is seriously good for not serious money.  Well done!"

 

I built a Bottlehead Foreplay in 2001 or thereabouts and can attest to the great instructions.  All the parts are available, everything is ready from the start.  If you get lost, there is a great community supporting just their products.  And if you get stuck after that, give Doc B. a shout out.  He'll be able to get you up and running one way or another.  

post #4047 of 4176

hello I want to build a otl amplifier, but I'm undecided between bijou and another amp like this http://www.hificollective.co.uk/pdf/otl_head.pdf
have different typology but, less high voltage, more choise boutique outputcaps and PS caps, work hell wiht low Z phone, good power and i love the 6080 look, but not have a PS slow start and need a CCS for better stage.

can someone tell if it is a good alternative or bijou is definitely better??

post #4048 of 4176

So I put my amplifier together last night and was powering up the PS as explained by the Cavalli website. The tube lit up but there was heavy arcing/sparking inside the EZ81 tube for a few seconds until it heated up (and then it went away). I was able to adjust the voltage to 250 VDC and it was stable. After a few more tries it seems like the tube finally burned out and I saw smoke. I have yet to take everything apart and look but I should find the evidence. I double checked and triple checked everything, I don't think I made a mistake. Faulty tube perhaps? If anyone knows what this may be please jump in. Needless to say that didn't make me very happy and I had to walk away. The tube heaters for the rest of the tubes worked fine and they lit up. I didn't use the PS to power the amp boards yet.

post #4049 of 4176
if you got any high voltage diodes around you can use them instead of the ps tube:)
post #4050 of 4176

I don't have any unfortunately. I guess I will need a new rectifier tube. I think the smoke was the fuse but I can't say for sure until I take everything apart. Would it make sense that if the tube was bad and shorting it would blow the 4A fuse for the transformer? I don't think there is anything wrong with the PS circuitry and I very carefully checked for shorts before powering up.

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