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Bijou All Tube Futterman Headphone Amplifier - Page 90

post #1336 of 3981
9/21/08 at 4:51am
I have put a couple of hours on the bijou now.

the soundstage is just so defined and massive. Its like each instrument / voice has its own space in my head. This is the standout feature for me. If i want to listen to the prodigy: diesel power, then the grunt of the soha and jisbos may be favorable, but anything else, the bijou just creates a holograph to explore.

It is also the first amp i struggle to analyse, the music just takes over. normally i am hyper critical and search for optimising. I may just be settled with this (....although there is the option of tube rolling!!!)
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post #1337 of 3981
9/21/08 at 5:45am
Quote:
Originally Posted by amphead View Post
fishski13, looking very good!

thanks.

anybody have tips on how to post/show FPE designs with a PC 'puter?
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post #1338 of 3981
9/21/08 at 5:49am
Print it to a file.
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post #1339 of 3981
9/21/08 at 11:04am
Quote:
Originally Posted by runeight View Post
OK. This should work and means that the PS is not connected to anything but the resistor. And this means that if your measurements at R7 and R8 are correct, there is a problem in the regulator. Could you please verify those voltages with just the 100k resistor loading the PS.

I have test with only the power suply board and the 100K resistor.
Same results: R7 : 309V and R8 : 321V.


EDIT:

I re check all my wires and rewire all the amp and now the pot works....
But i only have 240V max at the power supply output.
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post #1340 of 3981
9/21/08 at 1:10pm
we'll see if this works. nope...
LL
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post #1341 of 3981
9/21/08 at 1:15pm
let's try again. he shoots and he scores???
LL
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post #1342 of 3981
9/21/08 at 1:31pm
That thing looks great, but oh man.. 21 x 6"? That thing's gonna be huge!
Are you building a balanced bijou?.. the two holes in the middle look like they were made for XLR's.
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post #1343 of 3981
9/21/08 at 2:27pm
Quote:
Originally Posted by fishski13 View Post
we'll see if this works. nope...
Edit: Never mind. I missed one of your posts.
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post #1344 of 3981
9/21/08 at 2:31pm
Quote:
Originally Posted by Dantes View Post
I have test with only the power suply board and the 100K resistor.
Same results: R7 : 309V and R8 : 321V.


EDIT:

I re check all my wires and rewire all the amp and now the pot works....
But i only have 240V max at the power supply output.
Dantes, if you are certain that these are the measurments on R7 and R8 when nothing is connected but the 100k resistor, then there is an internal problem in the PS. It could be that the mosfets are toasted.

However, since the trimpot seems to work, this says that they working. So your measurements are inconsistent.

In order to get 250V from the regulator it must have at least 260V at R7. You are not getting this with your transformer and EZ80. The EZ81 will help to increase this voltage, but we have to find out why your PS is drawing 20mA when it is not loaded.

Please check it over carefully and make sure that all of the parts values are correct.
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post #1345 of 3981
9/21/08 at 4:19pm
Quote:
Originally Posted by JamesL View Post
That thing looks great, but oh man.. 21 x 6"? That thing's gonna be huge!
Are you building a balanced bijou?.. the two holes in the middle look like they were made for XLR's.
balanced yes. the 2 larger diameter holes are for Neutrik XLR/phono combo jacks, and the 2 outer, smaller holes are for the stereo pots. the rectangle on the left is for a rocker switch, probably slightly recessed. i'm going for a retro 80s muscle amp look, faceplate handles as well. cost is $89!!! plus an acrylic sheet from the hardware store.

and we have PS lift off...



PACE
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post #1346 of 3981
9/21/08 at 4:30pm
why the connection between heaters and star G at this point.... did i forget something when i finished mine??
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post #1347 of 3981
9/21/08 at 5:59pm
Quote:
Originally Posted by adamus View Post
why the connection between heaters and star G at this point.... did i forget something when i finished mine??
i'm going with Amphead's Mod, grounding the heater secondaries with a pair of1/2W 100R in series to star ground. as far as i have gleaned from this thread, there is no downside with removing the heaters from the bias chain. R9,10 and C7 have been left out of the board.

PACE
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post #1348 of 3981
9/21/08 at 8:44pm
Quote:
Originally Posted by adamus View Post
why the connection between heaters and star G at this point.... did i forget something when i finished mine??
adamus, if you've installed all of the components on the PS board then your heaters are properly biased and you don't need to do anything else. Particularly if you're not hearing any noise from the amp.

The amphead mod is available in case someone is experiencing unexplained noise that might be coming from the heaters. You can find this mod on the website, bit I think it's best to leave the amp as is if it's not causing you any problems.
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post #1349 of 3981
9/21/08 at 10:35pm


heaters are working!
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post #1350 of 3981
9/21/08 at 10:57pm
Quote:
Originally Posted by amphead View Post
fishski13, looking very good!

Pabbi, let's pull the trigger on doing the 17x17. I only have your budget in mind with any of this. And the mounting of parts into the new chassis, with new wiring is going to proceed fairly quickly. The only thing that could slow it down with new chassis would be if there was a borderline/bad component installed right now. And I don't believe that is the problem. Thanks for peaking my interest in the "mystery" box. ;-)
It's actually all in one box, and will go out first thing tomorrow, where you should see it all Wednesday. We won't clutter this thread with the 'extra' contents, but other than the case and wire, all will be yours to do with as you see fit - it should make a nice play pretty, well with a bit of cleanup - or, parts as you should need them.

The case has a couple of aluminum plates screwed to the bottom, which are just spare material, and I hated to just throw it away - use it as you see fit. If nothing else, I can machine it into a trans cover, should that need to be cut out of the top plate (I anticipate it will, but can certainly do that later). If it makes sense to mount the tranny on the cover, that would be acceptable as well. I definitely need to drill the top plate for ventilation, but was going to wait until the boards were mounted to punch the holes, especially for venting the tubes.

Do feel free to proceed any way you feel necessary.

I am traveling until late Wednesday or mid-day Thursday, but will respond asap then.

And, thank you - this is all really above and beyond - I feel luckier than KRMathis...
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