[adamus]

that all looks good, and the joints look ok.

How about the star ground - does the continuity check out as it should?

If so then then next thing to check is the NFB pot

Then check out the voltages against the labelled schemeatic on cavalli audio

 

[Olli1324]

NFB:

The connections on the NFB pot.

The connections to the board.

The cool thing is that when I put my finger through that coiled loop, hum increases.

 

[adamus]

you sure that nfb pot is wired right, check the diagram... i cant work it out from the pic but you seem to have too many wires....

it looks like you have it star grounded?

 

[Olli1324]

It is not star grounded so far as I can see..

For the NFB pot: I have the Reds going to 1 tab of each gang, browns going going to the middle tab of each gang and teh purples are connected the final tabs of the gang to the middle (brown) tabs. Is this not correct? (and then The red from each gang and the brown from each gang head off to the NFB terminals on the amp boards, as can be shown in my last pic).

 

[balderon]

Definitely check the NFB wiring. Looking at the twisted brown and red wires in your picture, it seems both channels are crosswired. As adamus suggested, study the NFB wiring at the bottom of The Bijou Headphone Amplifier. I would expect only the wires from each channels NFB terminal to be soldered to each "gang" of the NFB pot.

 

[adamus]

shouldnt the purple just be ashort jumper? why the length?

 

[Olli1324]

The length because when I was tacking on wires in anticipation of wiring it up, I didn't realise that they were just jumpers; so I coiled it up and left it so. I just cut them down a bit though; now I can actually see what is going where.

Those pics should clear up the wiring. Is this wrong?

 

[balderon]

Yes the NFB is wired incorrectly. The red pair (one channel) should be wired to the outer and center (jumpered) posts of one gang and the the brown pair (other channel) should be wired the same way on the second gang.

When I used the same NFB pot I had significant problems with hum until the I grounded the outer frame of the NFB pot to the star ground.

 

[adamus]

yep, look cross wired to me. ' recessed vocals' gave it away. vocals are typically centred, so out of phase or cross wired cancels them.

why is the purple so long? where are the ends going?

 

[ujamerstand]

.

 

[Olli1324]

The purples are still that long for ease of stripping and tying together; I don't have any electronics tools here so I didn't want to make things to hard by cutting them down tiny.

Anyway, the good news is....

IT SOUNDS AWESOME!

Thank you so much Adam and Balderon for spending your evenings helping; I'm very grateful. And slightly embarrassed it was such a small little thing!

A pretty successful build! Hang on... Still got to sort out the lid...!

 

[adamus]

great stuff.

For the lid let me give you a small piece of advice... DO not use a hole saw, they dont play well with the steel.

Instead invest in chassis punch fro rapidonline. best £10 you will spend.

 

[adamus]

and one more thing, dont star ground the earth inlet, that should have its own very secure grounding point at nearer the inlet.

 

[Olli1324]

Thanks for the advice

 

[balderon]

This is great news Olli1324! Looking over your pictures you have done a great job on this build. I'm glad your Bijou is alive and well. Congrats and Enjoy!