[naamanf]

You do not want to run a sub off the B22. If you get a pair of bookshelves and want more bass look into getting a powered sub. As far as speakers go you are going to want to look for ones that have high efficiency. I also suggest you go back and read about using the B22 as a speaker amp and the power supply and cooling requirements.

 

[swt61]

Agreed.
I'm not running any speakers off of my β22 yet, but if I do I'll make certain they're extremely efficient, as I don't have the proper larger heatsinks for anything else.
I have two powered subs that have XLR inputs, and I run them from the second XLR outputs of my preamp. Most powered subs have line level RCA inputs, and you can do the same thing with single ended RCA outputs of your preamp.

 

[el_matt0]

ok so high efficiency bookshelves would be the way to go? yea i was planning to add on a second s22/trafo. was planning to however try it with just the stock heatsinks at first unless im strongly advised against doing that. im new to the speaker world anyone mind throwing out a few names or brands of some quality high efficiency bookshelf speakers i could possibly look into purchasing?

 

[liwei]

Hey all, could I get an estimate on how much a balanced B22 (4 board implementation) costs?

I need a new rig and I'm thinking about going the diy route this time to have some fun and save a little bit of money.

Opus dac > Balanced B22 > Balanced AKG701 is what I'm thinking about right now.

Thanks

 

[swt61]

Quote:

Originally Posted by el_matt0 /img/forum/go_quote.gif ok so high efficiency bookshelves would be the way to go? yea i was planning to add on a second s22/trafo. was planning to however try it with just the stock heatsinks at first unless im strongly advised against doing that. im new to the speaker world anyone mind throwing out a few names or brands of some quality high efficiency bookshelf speakers i could possibly look into purchasing?

I have no idea what your budget is, but here are a few choices.

CBM-170 SE High Performance Bookshelf Loudspeaker

DECWARE / High Fidelity Engineering Co.

The Decware are particularly nice, the MODEL MG944 are 94 db., and would probably negate the need for an additional subwoofer.

 

[naamanf]

Quote:

Originally Posted by liwei /img/forum/go_quote.gif Hey all, could I get an estimate on how much a balanced B22 (4 board implementation) costs? I need a new rig and I'm thinking about going the diy route this time to have some fun and save a little bit of money. Opus dac > Balanced B22 > Balanced AKG701 is what I'm thinking about right now. Thanks

You are looking at about $1200 as a base price. Price can rapidly increase from there depending on the components used.

 

[el_matt0]

in the case of the b22, if using an alps quad-pot as the potentiometer, is there any need to consider unscrewing one of the "back" screws on the potentiometer housing and wiring that to one of the signal grounds (as I've done in my Millet Max)?

 

[amb]

Quote:

Originally Posted by el_matt0 /img/forum/go_quote.gif in the case of the b22, if using an alps quad-pot as the potentiometer, is there any need to consider unscrewing one of the "back" screws on the potentiometer housing and wiring that to one of the signal grounds (as I've done in my Millet Max)?

You would only need to do that if your front panel where the pot is mounted to is not connected to ground (i.e., a non-conductive panel).

 

[el_matt0]

will i truly be out of luck if my plan is currently to use 2 sigma 22s with a 100VA trafo for each to power my 4 b22 boards in order to run a pair of small high-efficiency bookshelf speakers as well as headphones? would i "be able" to get away with this just using 2 s22s or is it a STRICT requirement / recommendation that i use one s22 board per b22 board (so in my case 4 s22s). just seems like a LOT just to power a pair of bookshelves, and i was pretty sure that i thought i had seen ppl do it with just 2 s22's before - but i could easily be wrong, wouldnt be the first time either!

 

[amb]

el_matt0, it's not a strict requirement. It's just a recommendation for more serious speaker driving duty. Ultimately the amount of current that the σ22 could safely deliver without burning itself up depends on the amount of heat that could be dissipated. There is a limit on how much two TO-220 MOSFETs per rail could do, even with very large, off-board heatsinks. By using four instead of two σ22 boards, then the current each one has to deliver is halved, which will result in half the amount of heat each MOSFET has to handle.

If you have efficient speakers, your room is not very large, and you won't be listening at high power levels for sustained periods of time, then one σ22 per two β22 boards is probably ok.

 

[el_matt0]

thanks ti. it is just for a tiny room in fact so i definitely wouldnt be thumping on the speakers too hard by any means. since this is the case and hopefully ill be able to get away with just 2 sigma22s, what about the heatsinks. should those definitely be upgraded to something bigger or off-board, or could i try and see what the results are like using the stock ones?

 

[amb]

You can try using the stock heatsinks first if you like. It would be good if you have some way to actually measure their temperatures. There are DMM thermocouple adapters and handheld IR thermometers.

 

[el_matt0]

K GUYS I NEED HELP! i had taken my b22 completely apart to re-wire neatly etc. i didnt change any of the components on the boards themselves. the only thing i really changed about the wiring from how i had it before (and working) is that I included 2 pairs of speaker binding posts through which i have wired my outputs so that I can down the line use speakers. I havent yet included my second sigma22 or the zobel networks - figuring that since im not going to be using speakers, it should be fine just "having" the speaker binding posts there right?

anyways, on to where the trouble began. after getting it all re-wired, i began biasing, the s22 looked good, 28V across V+ and G on all the terminals. I spent most of the morning in the slow process of trying to adjust r34 to 75mV on all the boards. after a good number of hours i managed to get it all level at 75mV, as well as getting the DC offset to within 0.5mV of 0. everything looked good, so i went ahead and plugged in headphones for the first time with audio, and initially everything sounded OK - a tad blurry, but OK. then i noticed in my left channel it seemed to be cutting out almost and had a faint buzz at times, the right channel seems fine. however im not sure if its a problem with JUST my left channel, seeing as it "sounds" the same on a SE pair of headphones out of one of either of the two single ended jacks (left side blurry etc).

unplugged the load and now my s22 is only giving out about 18V across V+ to G (on all the terminals), when it was at 28V a few hours ago! my DC offset readings look fine without a load plugged in, but now i cant even get a reading across R34 on the mV scale, i think its in the realm of 0.5V or so. HELP! where should i start - im in a bit of a panic so anything is appreciated. ill snap some pics in a bit. sorry for the long post guys

 

[el_matt0]

k BIT of an update prior to posting photos. just started it up again and the s22 is pumping out 28V again fine, biased again, everything looked ok so i tried running it under load with headphones again. everything seems fine at first (sounds good, nothing audibly wrong). checking mV across R34 while listening, some boards stray from 75, to around 90 or so, but thast it. after a number of songs i decided to turn up the volume, near to the max end of the range i heard the left channel suddenly buzz somewhat noticeably, and then began alternating between a quieter and a louder volume every second or so. now the reading across the R34 is ranging from 180-250mV or so and even with the volume reduced again, the left channel is audibly "impaired". i believe the problems are once again rectified upon startup. what could i be looking at here - is this specifically a direct result of my lack of zobel networks (unstable under load)? the only reason this strikes me as odd is that this exact b22 setup without any components changed, just the addition of speaker posts and single ended outputs, worked FINE about 2 weeks ago before i took it apart! any help from you b22 gurus would be, as always, much needed / appreciated

 

[naamanf]

Zobel network won't be needed till speakers are connected. If everything worked before you rewired it that means you did something wrong on rewiring. Look everything over with a fine tooth comb. Triple check to make sure everything is going where it is supposed to. Check all your solder joints and look far any solder/wire.