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Bijou All Tube Futterman Headphone Amplifier - Page 278

post #4156 of 4179
Quote:
Originally Posted by LV26 View Post
 

First I need change my headphones to high impedance (DT880 600 Ohm I think)

No chance to get more performance with Bijou and Grado SR80i.

...

For info: Bijou output capacitor (C5) rated for 250V.

 

That seems reasonable ; it is already a very nice amp you have there. Better spend money on better headphones.

 

Yes, I know for the bijou.... I'm a bit paranoid however and prefer to use output caps rated for the full unregulated voltage.

post #4157 of 4179

Just find very interesting parts

http://www.digikey.com/product-detail/en/C4ATDBW5600A30J/399-6223-ND/2783185

http://www.digikey.com/product-detail/en/C4ATFBW5400A3NJ/399-5949-ND/2704603

 

Probably will be usefull for you. Look at datasheet (VERY low ESR and DF)

 

+ "100 USD" Champion :)

http://www.digikey.com/product-detail/en/C44AFGR6200ZE0J/399-6265-ND/2783746


Edited by LV26 - 5/25/14 at 2:24pm
post #4158 of 4179

Detaching the mosfets (Q1 and Q2) from the power supply board will let me relocate them in my case and provide better heat sinking. There are significant voltages present on the legs, but if they are adequately insulated, should I expect any bad behavior by adding 3" of pig-tail to them?

post #4159 of 4179

You should not really be worried abt the mosfet being cooled. I have mine on the original position next to the tubes in an enclosure with little airflow and well they work fine. Stability is more abt "constant" heat than being cool ( assuming ur in the working temp range).

 

Any way, no if u use insulated wire ull not run into any problems. However if you really are looking into lowering the temps I would advice ditching the heat source (aka tube) and replacing it with 2 high voltage. :)

post #4160 of 4179

Hi, I just finished putting my Bijou together last Saturday evening and was able to listen to it and everything sounded just fine, the PS was giving out steady 250V. Then The day after I plug it in when I get home from work and just let it sit there for around 2 hours, when I get back to it I decide to measure the output of the PS again. This time it shows 276V and then the R4 resistor on the board burst into flames. I replaced it with a new one this morning and readjusted the trimpot to lower the Voltage, the R4 blew up again as soon as I put power on the board. I don’t even have time to check the Voltage before it blows. So now I’m thinking something else must be wrong.

I bought this from glassjaraudio.com, and I’m using Hammond 370DAX.

Does anyone have any idea what I’m doing wrong here?

post #4161 of 4179
Quote:
Originally Posted by hrolfur View Post

Hi, I just finished putting my Bijou together last Saturday evening and was able to listen to it and everything sounded just fine, the PS was giving out steady 250V. Then The day after I plug it in when I get home from work and just let it sit there for around 2 hours, when I get back to it I decide to measure the output of the PS again. This time it shows 276V and then the R4 resistor on the board burst into flames. I replaced it with a new one this morning and readjusted the trimpot to lower the Voltage, the R4 blew up again as soon as I put power on the board. I don’t even have time to check the Voltage before it blows. So now I’m thinking something else must be wrong.

I bought this from glassjaraudio.com, and I’m using Hammond 370DAX.

Does anyone have any idea what I’m doing wrong here?

 

can u put tome quality pics of both the back and the front of the psu boards?


Edited by yiancar - 7/15/14 at 7:15am
post #4162 of 4179

Sorry I can't upload picture strait to this page with my account (it's new). 

Here is a Imgur link http://imgur.com/a/S7Uph

 

Thanks.

post #4163 of 4179
Quote:
Originally Posted by hrolfur View Post
 

Sorry I can't upload picture strait to this page with my account (it's new). 

Here is a Imgur link http://imgur.com/a/S7Uph

 

Thanks.


only thing i cn suspect is faulty mosfets , however just to be sure can you also mesure the ac output voltage of the transformer as well as dc voltage between tube pin 3 and ground. just have ur meter ready, turn on get a mesurement turn off. dont replace the burned resistor, it doesnt matter for this test

post #4164 of 4179

Maybe someone here can help me. I've been searching around online and I have been unable to find out the power output of the Bijou. Does anyone know what it measures? I think it's unable to drive the HE500's to very high volume due to bad bass distortion when the volume pot is at around 60% and no negative feedback. It could also be the headphones and their limitation. Anyone have experience with HE500's and their Bijou amp?

post #4165 of 4179

Hello, all

 

Any activity with Bijou? Or summer time...

My Bijou finally "pre-burned".

I`m waiting for DT800 600 Ohm. Will compare with Grado 32 Ohm.

 

Good Luck to all

-- WBR, Victor

post #4166 of 4179
Quote:
Originally Posted by LV26 View Post
 

Hello, all

 

Any activity with Bijou? Or summer time...

My Bijou finally "pre-burned".

I`m waiting for DT800 600 Ohm. Will compare with Grado 32 Ohm.

 

Good Luck to all

-- WBR, Victor


meaning construction or improvement ?:)

post #4167 of 4179
Quote:
Originally Posted by yiancar View Post
 


meaning construction or improvement ?:)


I mean sound improvement with DT880. :)

At least I would be surprised if Grado SR80i better then Beyerdinamic DT 880 (600 Ohm) with Bijou. :)

post #4168 of 4179
Quote:
Originally Posted by LV26 View Post
 


I mean sound improvement with DT880. :)

At least I would be surprised if Grado SR80i better then Beyerdinamic DT 880 (600 Ohm) with Bijou. :)


I assume u removed nfb?

post #4169 of 4179

No yet.

I haven`t DT880 at this moment

I`m waiting for delivery.

 

You wrote about totally removed NFB (and NFB potentiometer too) or using minimum NFB with DT 880.

Are any sound difference really BIG?

No NFB vs Minimum NFB

post #4170 of 4179
Quote:
Originally Posted by LV26 View Post
 

No yet.

I haven`t DT880 at this moment

I`m waiting for delivery.

 

You wrote about totally removed NFB (and NFB potentiometer too) or using minimum NFB with DT 880.

Are any sound difference really BIG?

No NFB vs Minimum NFB


there is some, just an "extra" bit, you should try it out, u can leave it on minimum on one channel and remove it completely on the other.

 

have u rolled any tubes?

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