[NoValidTitle]

Quote:

Originally Posted by amb /img/forum/go_quote.gif The board thickness is 0.062" (plus a smidge more for the copper, plating and soldermask).

Sweet, thanks. Time to edit my model.

 

[dbfreak]

What is/are the benifit/s of installing a loop out for the Beta22? In other words, what is it's purpose?

 

[linuxworks]

loop-out just saves you from swapping cables or installing switches to let a source signal pass thru or 'around' a device.

if I have a line-out from a dac and I want to send it to my phones amp and ALSO my spkr amp, a pass-thru would be useful for that.

 

[dbfreak]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif loop-out just saves you from swapping cables or installing switches to let a source signal pass thru or 'around' a device. if I have a line-out from a dac and I want to send it to my phones amp and ALSO my spkr amp, a pass-thru would be useful for that.

Thanks, makes sense!

 

[jtostenr]

Would this also work for passing the signal along to a powered subwoofer? Or should there be a different output for that?

Jeff

 

[linuxworks]

I did exactly that - to parallel the input wires with some outputs that go to my sub.

in fact, I go thru a 2nd vol control so that I can remotely control sub volume.

you may want a LP filter or band split (hp/lp) or just use the one in the sub.

but yes, a passthru has good use for subwoofers.

passthru is just a y-cable, folks

 

[Nebby]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif I did exactly that - to parallel the input wires with some outputs that go to my sub. in fact, I go thru a 2nd vol control so that I can remotely control sub volume. you may want a LP filter or band split (hp/lp) or just use the one in the sub. but yes, a passthru has good use for subwoofers. passthru is just a y-cable, folks

Would that affect the sound? How about two sub-outs? Would that require a buffer of some sort?

 

[linuxworks]

you are dividing the 'drive' between 2 loads.

in practice, loads on inputs are high-z so it should not hurt. but some voltage will get 'lost' in terms of slightly lower output.

proper way is to buffer each output. benefit includes having gain controls on each buffer so you can 'trim'.

 

[ShinyFalcon]

Quote:

Originally Posted by ShinyFalcon /img/forum/go_quote.gif The slots are approximately 2mm high, so I'm definitely hoping that it will slide in. What I was concerned about is the vertical distance from the edge of the σ２２ to the heatsinks' edge. The case's slots are about 2mm wide.

The board slides in perfectly. However I'm unsure if it's safe for the bottom ground plane to have the potential to short into the case. I'm sure the σ２２ wasn't designed as a slide-in board, but this solution is the only way that the σ２２ and the transformer can fit into my particular case. Otherwise I'll have to separate them or go for the Hammond case. Or, what I could do is hack at it with a knife and remove the portion of the plane that is contacting the case.

I do recall that someone attached a wire of some sort into the transformer's mounting kit, and that it was considered something bad (short something). I don't know if it's related to my situation, but it doesn't hurt to know.

 

[amb]

Quote:

Originally Posted by ShinyFalcon /img/forum/go_quote.gif I do recall that someone attached a wire of some sort into the transformer's mounting kit, and that it was considered something bad (short something). I don't know if it's related to my situation, but it doesn't hurt to know.

Just don't use the toroid's mounting bolt as a ground point for chassis grounding. For that matter, don't let the head of that bolt touch anything at all except the toroid's top-mounting washer/dish. It's ok for the bottom of the bolt to be electrically connected to the chassis.

 

[oneplustwo]

Man... I think my first beta and all the other projects I've done going so well is making me too comfortable with this stuff (ie, sloppy). I accidentally powered up my beta boards with V+ and V- switched this morning. Damnit. Nothing smoked, but I noticed the trafo getting pretty hot and when I checked the voltage coming out of the sigma it was low. After disconnecting the beta, the sigma seemed ok. First thing I checked on the beta was the V+ and V- and of course there you have it. Any guidance on trouble shooting steps before I power up again?

 

[amb]

oneplustwo, if your σ22 still puts out the correct voltage, then there is a good chance that all is well. The β22 should have survived, because its output MOSFETs have an internal reverse body diode that looks like a dead short to the power supply if the V+ and V- were swapped, which should protect the β22 from damage. Fix the wiring and power up again. After you successfully adjust the bias, check the σ22 to see if all four MOSFETs get warm. If any MOSFET stays cold, then maybe the 0.47 ohm resistor in series with that MOSFET is blown.

 

[oneplustwo]

Thanks Amb. That's exactly the direction I was looking for! Any similar guidance for the sigma 22 that I messed up by putting in CR2 backwards?

 

[amb]

I don't remember what your broken σ22's symptoms are. But the standard thing to do is to check MOSFETs for shorts, check 0.47 ohms resistors for open circuit, and check your BJTs using the DMM's diode check mode (I described this several times elsewhere, search for it). The CRD itself is probably ok, but if you have a spare, replace it anyway.

 

[rshuck]

Quote:

Originally Posted by NoValidTitle /img/forum/go_quote.gif Sweet, thanks. Time to edit my model.

Are you by chance going to make this model available for download?