[boozcool]

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif The boards are isolated from the attenuator. I see signal in(white) and signal out(purple) of the attenuator, but no ground. Check that next, and make sure the attenuator ground is connected to board ground.

It seems Board 1's ground (black wire) is connected to Board 2 and Board 3's ground, but makes no connection to the attenuator. The attenuator is connected to the 'Input' of Board 1 and 'Input' of Board 2 (purple wire)

 

[Beefy]

Quote:

Originally Posted by oneplustwo /img/forum/go_quote.gif For full disclosure, this is the B22 that I......

Wow dude, you really should fit your ground loop breakers in a more secure manner.

 

[digger945]

Quote:

Originally Posted by boozcool /img/forum/go_quote.gif It seems Board 1's ground (black wire) is connected to Board 2 and Board 3's ground, but makes no connection to the attenuator. The attenuator is connected to the 'Input' of Board 1 and 'Input' of Board 2 (purple wire)

This is one diagram from the amb.org website. Maybe you can see how the grounds are all connected. RCA/attenuator/all boards and in your case with active ground the only thing not connected is headphone out ground, which is connected to the output of the ground channel board. Everything else needs to be connected together. Star ground isn't necessary, a daisy chain will work fine.

The 2 dots on the left side of the volume are grounds. See how they run up and connect to both RCA grounds, and the other way they connect to each of the 3 amp board grounds.

If you save this to your computer, or save the image at The β22 Stereo Amplifier to your pictures, and open it up with paint, you can blow it up and see it better. I tried but paint won't let me draw lines on the image, only magnify.

 

[boozcool]

dbl post

 

[boozcool]

Awesome, thank you Digger945

So now, it appears I should connect the attenuator to the ground wire, and run the ground wire to the L/R Inputs, correct?
Also, try and move the wires to run down the side instead of the middle of the enclosure
Should I also remove the R1 resistor on the gnd board?
As for the ground break loop, how would you secure it to fit better?

 

[luvdunhill]

hard to imagine how this could have happened in shipping.

 

[IPodPJ]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif I've always (well, on both my builds) added zobels. they can only help and cannot (just cannot!) hurt. they should be in every build, imho.

Aren't the Zobel networks only required if you are using it to drive speakers? If you are only using it for headphones, what would be the benefit of them? Wouldn't it raise your output impedance to 22 ohms?

 

[linuxworks]

I believe the zobel is tranparent and only helps. therefore, there is no diff in 'phones vs speakers' in my mind. if something keeps the oscillation (chances) down, I'm all for it.

so in both my builds, I just installed it as a matter of course.

 

[amb]

Speakers tend to be more reactive in nature so a zobel should always be required. Headphone loads are more benign but there are exceptions, so sometimes a zobel might be warranted. It is transparent as far as the β22 is concerned, so it doesn't hurt to just add it.

 

[IPodPJ]

Ok, will do. What resistors would you recommend? Vishay?

 

[amb]

For the zobel, use 2W rated 22 ohm metal oxide resistors (similar to the 0.47 ohm ones on the β22 and σ22. Xicon or Panasonic, etc.

 

[boozcool]

Does anyone know where I can find a picture and/or specific instructions on how to attach the zobel network to the headphone jack of my B22?
Would it be ok to just soldier the resistor and capacitor wires together in series, or is there another better technique? After connecting them, how would I connect them to the headphone jack?
Also, how do I connect/disconnect the 3 wires from the o22 which power the b22 boards? Do I use a screwdriver?
Thanks!!

 

[digger945]

Quote:

Originally Posted by boozcool /img/forum/go_quote.gif Also, how do I connect/disconnect the 3 wires from the o22 which power the b22 boards? Do I use a screwdriver? Thanks!!

May I suggest, that you label the wires before you remove them so that you can make absolutely sure they are reinstalled in the proper terminals when you're finished working on your amp.

 

[boozcool]

Quote:

Originally Posted by El_Doug /img/forum/go_quote.gif Despite a shielded transformer, unless the wiring 100% perfect, the B22 seems to love to pick up hum

Just an update, I unscrewed and repositioned the wires from the o22 to the b22 boards, and the hum has disappeared

Now, all that's left is the zobel network to fix the hiss

 

[digger945]

Quote:

Originally Posted by boozcool /img/forum/go_quote.gif Just an update, I unscrewed and repositioned the wires from the o22 to the b22 boards, and the hum has disappeared

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Quote:

Now, all that's left is the zobel network to fix the hiss

It's a very inexpensive thing to do, but I don't think it will make any hiss go away. Are you talking about hiss when you turn the volume all the way up as loud as it will go? ...with the source connected?