Roll Call: Who's building, built, or thinking of building a beta22?

[Hottuna_]

Alrighty, did the resistance to ground comparison with one of my other boards.
Found the problem in the Q11, Q12, Q15, Q16 cluster.

Pulled them all out and looked at the traces and the from R11 and R12 to the base of Q11 and Q12 were mis-etched under the components themselves. See attached pics.

I dug out some old very very thing wire from back in the day when I had to do similar fixes. (though back then it was more my fault not picking up the error in protel before sending to fab)
Soldered on the wire and fired it up.
Works just fine.

Thanks to everyone who gave suggestions and ofcourse linuxworks for giving me the idea for that test.

 

[amb]

If yiou could see the under-etched blotch, then it's easier to simply cut that blotch away with an x-acto knife rather than adding wires.

 

[Hottuna_]

Well in this case it was over-etched.
Attachment 24153

Just finished biasing and zeroing DC offset.
Still a fair bit of casework/assembly/wiring left to do.

Can't wait to get it up and running

But I've had enough for today. Closing in on midnight here down under.

 

[amb]

Ah, ok. Instead of the long wires you could have just scraped a little bit of the soldermask away and tack-soldered a little resistor lead cutoff to bridge it. But anyway...

 

[linuxworks]

you found it and got it working! nice!!

bet it feels REAL GOOD now (lol). the more 'sweat' you put into it, the more rewarding it is once it finally works.

congrats

 

[Magsy]

Well done on that fix, I've been in that boat before and you start to lose the will to live but making it working is an amazing feeling!

Can somebody clarify how to connect a SE source please?

If I understand the diagram correctly, I must short the input of two of the boards (the -) ones to ground but this must take place between the boards and the pot, not between the pot and the jacks?
Can I just bridge the input and gnd pads on the two boards?

I guess I lose half the gain by doing this also?

Thanks

 

[amb]

Quote:

Originally Posted by Magsy /img/forum/go_quote.gif Can somebody clarify how to connect a SE source please?

Just like how you saw it in the diagram at the β22 website "Other options" section.

Quote:

If I understand the diagram correctly, I must short the input of two of the boards (the -) ones to ground but this must take place between the boards and the pot, not between the pot and the jacks?

Correct, because you don't need a volume control on the "cold" amps when switched to unbalanced inputs. You only need those board to become referenced directly to ground.

Quote:

Can I just bridge the input and gnd pads on the two boards?

Isn't that basically what the diagram does with the switch?

Quote:

I guess I lose half the gain by doing this also?

Yes, but only if your unbalanced source outputs half the total output voltage swing compared to your balanced source.

 

[hasanyuceer]

Where can we find ß22 and sigma22 complete kits? (w/out chassis of course)

I want to buy all kit and pcb's, and only solder them, then start to use...

 

[nattonrice]

Blind stuffing comes highly unrecommended.
Casing that is not well thought out (or non-existent) is asking for hum and other problems.

I believe Glass Jar Audio stocks pcb+component kits.

Before diving into this you will want to read the threads here and especially the 3 threads at headwize FROM START TO FINISH.
Most epic failures can be prevented that way.

 

[hasanyuceer]

Thanks nottonrice... I will look at Glass Jar Audio..

I know it's like diving but i am not unfamiliar to pcbs and all these stuff. (Electronics Eng.) But i will listen your advice and read the threads...

 

[linuxworks]

do not build a b22 unless you are prepared to DEBUG it.

this is not a heathkit and this is not just 'solder parts and it goes'. sometimes there are bad parts. sometimes there are bad boards. sometimes there are other things.

do not be fooled that its just assembly work.

don't let your ego assume that you can build this.

that's all I have to say. I see a lot of bravado about 'I want to build the best!' but people FORGET that debugging is often a part of the build and most builders, sorry to say, are just not up to the task (being really honest, here).

work your way up. start sensible. that's my suggestion.

b22 is a final build not a FIRST BUILD.

 

[hasanyuceer]

My desire to get all parts in one time is because where I live. Its hard to find audiophile parts here. Only a missing capacitor loses me at least 10 days...

This is why I am so on to finding all parts as kits..

 

[linuxworks]

I would suggest ordering extra parts, then. I've had to re-order and even getting the parts the same week for me is too much wait

order extras of the things that need matching and also the final transistors AND .47 resistors. order lots of those

just in case.

no need for extra crd's but do order extra fets and transistors of all kinds.

maybe extra caps (electros) in case you reverse some. I did (just 1 but it blew out a WHOLE SUB CHAIN of parts due to that!)

again, can't say this enough: order extra parts since you are making 1 big shipment.

 

[johnwmclean]

Even before soldering any components a continuity check with the pcb matching back to the schematic would be advisable.

 

[hasanyuceer]

Thanks for advices, i am noting down them all...