b22 configuration discussion...

[Solude]

I currently have a 2ch build with a gain of 5 that I like so like all things we like I want to change it

So what are the real world, measurable and not measurable differences in:

2 v 3 v 4 channel builds

1 v 2 case builds

Assume single o22 for all three. Gain set so output would be similar. Same parts selection except the pot etc.

Go!

[grawk]

a 2 channel vs a 4 channel build with the same gain, the 4 channel build would be 4x louder

[Solude]

I like comments like that, good for the wallet.

[Beefy]

Well, it really depends on your source.

The balanced output on some sources is twice as hot as the unbalanced output; in this case, the balanced output will indeed be louder if the gain is kept the same. But if your balanced output is the same voltage as unbalanced output, then the volume will be the same.

[Solude]

More details...

My source is 1.4v SE, 2.8v balanced. Which is why I would set the gain to 2x balanced instead of 5x. Assume the output of the 2/3/4 channel amps is the same for this discussion.

[Beefy]

My source is 1.4v SE, 2.8v balanced. Which is why I would set the gain to 2x balanced instead of 5x.

That sounds reasonable.

[Dusty Chalk]

But if your balanced output is the same voltage as unbalanced output, then the volume will be the same.

Wouldn't the gain coming from the amp double, if you kept the gain the same on the individual boards?

[Beefy]

Lets say gain of 5 from 1VRMS unbalanced. Each amp board produces 5VRMS.

Lets say gain of 5 from 1VRMS balanced. Each phase is 0.5VRMS. Each amp board produces 2.5VRMS. 5VRMS across the driver.

[luvdunhill]

Lets say gain of 5 from 1VRMS unbalanced. Each amp board produces 5VRMS.

Lets say gain of 5 from 1VRMS balanced. Each phase is 0.5VRMS. Each amp board produces 2.5VRMS. 5VRMS across the driver.

correct. In fact, my previous source was exactly this way... it's more common than people think.

[xand1x]

11x gain is a must!

[swt61]

correct. In fact, my previous source was exactly this way... it's more common than people think.

Yep, mine too.

I think the real question is what do you want to drive with the amp?

If you just have extra money to burn, and think a balanced β22 is sexier that's fine, but there are probably better ways to spend the money. If you have a hard load to drive that's a different story. I'm not absolutely sure that just going balanced is worth that kind of cash layout. There are gains IMO, but they're fairly subtle.

[Solude]

Lets try this another way. I'll answer the question, you guys correct me

1 v 2 boxes, the idea is to keep the transformer away from the amp board. Sounds reasonable but most commercial builders don't so is it because its not really a problem or is the added cost something that makes it less attractive for them.

2 v 3 channel, equal power, increased noise, reduced dampening factor, increased output impedance, drops noise on the line. My impression, more meh. The faults that would require the benefits likely don't exist in the real world and the downsides are kind of moot since noise, output impedance are so low to begin with so... meh.

2 v 4 channel, increased output impedance, increased noise, increased power and slew rate. More of the same negatives that don't add up to much and benefits that given the performance of the b22 seem to be adding a whole other level of overkill.

That about right

[Beefy]

1 v 2 boxes, the idea is to keep the transformer away from the amp board. Sounds reasonable but most commercial builders don't so is it because its not really a problem or is the added cost something that makes it less attractive for them.

The B22 does tend to pick up more magnetic noise than other amps, so it would need to be handled differently from most other commercial designs. I still maintain that in your case, magnetic noise it isn't an issue.

That about right

You are WAY overthinking this. Steve nailed it pretty well, I think. If you have a really difficult load then balanced makes more sense. For most headphones, there is little benefit.

But it really seems to come back to your source again, and how it handles balanced versus unbalanced. If one of the outputs it 'better', that will make much more of a difference than any of the other factors like a fraction of an ohm on the output impedance.

[K3cT]

Don't bother if you don't have a balanced source.

[Solude]

My source's output is fully discrete differential drive. If you look at the circuit board you can see the four channels. That said they are all the same so the effective difference is CMR and output level. The headphone at this point looks more and more to be the LCD-2 which though not efficient is about as easy a load as they come. I certainly don't need more drive than I have now. Loud for me right now SE happens are about 9 o'clock.

Think what it really comes down to is... do I keep my current clean but DIY 2ch single case b22 or snag the 3ch two box Rockhopper has up for grabs. Also messaged him about modding it to balanced but I think thats throwing money into a hole. I think I read KG was not a fan of 3ch builds and gave tech reasons but like AMB defense of balanced drive may not really mean anything in the real world in context of the b22. Certainly not about to ask thrice? to remove a board though

[grawk]

Why not just do whatever you think is best, and not depend on others' opinions?

[atothex]

Modding a 3-board Beta to be balanced? Wouldn't that basically require gutting it? That seems kinda inefficient...

[Salt Peanuts]

Unless the policies have changed, Rockhopper also isn't taking any custom orders.

[Solude]

"High quality custom designed black anodized cases with enough room to upgrade the amp to a 4-channel balanced amp in the future."

Not going to go balanced after all this but just saying. I think my best move is to simply polish my current build and call it a day. Some loctite and some feet should finish it.