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Bijou All Tube Futterman Headphone Amplifier - Page 277

post #4141 of 4218

Flatbroker,

 

Try connect Volume and NFB shafts to star ground point.

This can help.


Edited by LV26 - 5/20/14 at 7:30am
post #4142 of 4218
Quote:
Originally Posted by LV26 View Post

 
Try connect Volume and NFB shafts to star ground point.
This can help.

The hiss is only audible with source paused and volume cranked way above listening level. With a little NFB it is gone. The HD600's sound better with about a 1/4 turn of NFB. Tightens the bass up and seems to exert a little control over everything else. I am completely blown away by the silence of this amp as it is.

That's a nice looking Bijou you built. What headphones are you using? I like the HD600's and HD580's with mine. DT880 is good. HD650 not so much. DT990's suck with this and every other amp I've ever tried them with, so no surprise there.
post #4143 of 4218

I`m curently use Grado SR80i... Yeah... not a good choice for Bijou.

But with low impedance headphone Bijou great too...

 

Will collect money for DT880 600 Ohm.

and newest (not designed yet) γ3 DAC form AMB Labs. :)

post #4144 of 4218
Unless you've lost more of your high frequency hearing than me, you ought to consider HD600 too. 600ohm DT880 bass is better, but I get burned out on them after an hour. HD600 are good for hours. Laid back but the detail is there.
post #4145 of 4218
Quote:
Originally Posted by flatbroker View Post
 
Quote:
Originally Posted by LV26 View Post

 
Try connect Volume and NFB shafts to star ground point.
This can help.

The hiss is only audible with source paused and volume cranked way above listening level. With a little NFB it is gone. The HD600's sound better with about a 1/4 turn of NFB. Tightens the bass up and seems to exert a little control over everything else. I am completely blown away by the silence of this amp as it is.

That's a nice looking Bijou you built. What headphones are you using? I like the HD600's and HD580's with mine. DT880 is good. HD650 not so much. DT990's suck with this and every other amp I've ever tried them with, so no surprise there.


Did you isolate the source of the hiss? Do you still hear hiss if you ground the inputs to the Bijou?

post #4146 of 4218
I haven't tried to isolate or eliminate it. It's great the way it is. Noise is imperceptible at even loud listening levels. Only get subtle hiss at near max volume with no NFB. Actually, I only mentioned it as a technical observation about how quiet these amps are. I surely didn't mean to disparage this great design, but if you are telling me I can get this thing dead black at max gain, I'm listening.
post #4147 of 4218

My Bijou has passed its smoke-test and is currently making music :)

 

I have it encased in a plastic toolbox. The boards are screwed to the under side of the lift-out tray. There is space to store the transformer under the tray, but I need to lift it out to kill the hum while it is playing. I'm still dreaming up the 'real' case for it. Right now, I'm leaning towards bamboo and brass.

post #4148 of 4218

Hello,

 

Some Bijou builders use Motor Run Capacitors

for output DC-blocking caps.

 

What is a best choice for Motor Run Capacitors?

Could you recommend some part numbers, please?

 

-- Regards, Victor

post #4149 of 4218

Most people using motor-run caps do so using surplus parts. At which point, part numbers are kind of pointless. What one guy could get 3 months ago is no longer available, but something else surely is. 

post #4150 of 4218
 

What is a best choice for Motor Run Capacitors?

Could you recommend some part numbers, please?

 

-- Regards, Victor

Look at ebay auction #251157598293.

100 mfd, 5 for $50.  They are Temco brand.  I have no idea if they are any good, but at $10 a pop they may be worth a shot.

 

Ebay #111355934421

80 mfd Dayton.  These should be good to go as far as construction quality goes.  No idea how they sound. $9 each.

 

A lot of the caps described as run caps have 3 terminals.  These are dual start/run caps and are not what you need.  

post #4151 of 4218
Quote:
Originally Posted by flatbroker View Post
 

Look at ebay auction #251157598293.

100 mfd, 5 for $50.  They are Temco brand.  I have no idea if they are any good, but at $10 a pop they may be worth a shot.

 

Ebay #111355934421

80 mfd Dayton.  These should be good to go as far as construction quality goes.  No idea how they sound. $9 each.

 

A lot of the caps described as run caps have 3 terminals.  These are dual start/run caps and are not what you need.  


Thanks

1st lot 65$ for delivery

2nd not available for delivery to my country.

 

Oil caps are not critical for me.

Also I can try to find them near my location.

 

-- Regards,

Victor

post #4152 of 4218

New motor run caps are difficult to find in values above 40uF (they exist but aren't stocked by major suppliers). The arcotronics/kemet C274AC35400AA0J is probably the most widely available.

 

In Europe, the audyn mkp-qs are probably your best bet for high value mkp caps.

post #4153 of 4218

Thank you.

I think Audyn a good choice (and available)

I think WIMA MKP10 available with 47 uF/400VDC... Need check stock.

 

BTW

What is a difference between Audyn QS and Q4 and Q6?

I compare tech. spec. I think they all provide very close parameters (DF, for example)


Edited by LV26 - 5/25/14 at 4:04am
post #4154 of 4218
Quote:
Originally Posted by LV26 View Post
 

Thank you.

I think Audyn a good choice (and available)

I think WIMA MKP10 available with 47 uF/400VDC... Need check stock.

 

BTW

What is a difference between Audyn QS and Q4 and Q6?

I compare tech. spec. I think they all provide very close parameters (DF, for example)

 

From the datasheet, the wima mkp10 stops at 22uF for 400Vdc.

 

I've no experience about audyn qs vs q4/q6. I've used some mkp-qs in the past, they seemed ok to me. There are some discussions on French forums, mostly about caps in speakers crossovers... some say that the qs are a bit better than the q4, some say that they sound the same. Many say that the ones rated for higher voltage sound better; it could thus be interesting to compare the qs vs the q6 (the 100uF exists in Q6 but not in qs-630).

 

As far as I'm concerned, pretty much any mkp will do for output coupling. It's not a position where specs are critical.

post #4155 of 4218

00940,

Thank you for the answer.

I decide to roll caps not now...

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.

 

-- With best Wishes,

Victor

 

P.S.

For info:

Bijou output capacitor (C5) rated for 250V.

WIMA MKP 10 series have a 33 uF/250V caps.

But I really like Audyn for highest available capacitance.


Edited by LV26 - 5/25/14 at 2:09pm
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