[haejuk]

I followed jcx's advice and skipped the 3rd channel board.  It saved me $100 and his arguments made a lot of sense as to why the 3-channel may not be better than 2 channel.  I was also unable to find anyone who definitively said "I have heard two channel and three channel builds and the three channel build sounds better."  The closest I found it someone who said they heard 2 channel, 3 channel, and fully balanced builds and said the sonic differences were minimal, if any.

 

[Zashoomin]

Quote:

Does anyone have an estimated finished cost (not including housing) per board?
 
Also has anyone messed with the gamma dac?

I have build a gamma 2.  and yes the biggest challenge is the surface mount.  also you really need to make sure that when you plug it with usb or walwart and you don't short anything I burned out a couple chips the first time 

.  But other than that it doesn't require any wiring and is a very nice little dac.  
 
Also does anyone know the any good enclosures for a 4 channel beta22?  And would you guys suggest separate enclosures for power supply?

 

[fishski13]

Quote:

I have build a gamma 2.  and yes the biggest challenge is the surface mount.  also you really need to make sure that when you plug it with usb or walwart and you don't short anything I burned out a couple chips the first time 

.  But other than that it doesn't require any wiring and is a very nice little dac.  
 
Also does anyone know the any good enclosures for a 4 channel beta22?  And would you guys suggest separate enclosures for power supply?

the amount of experience/chassis work you can do and the quiescent current bias will drive the chassis design.
 
a single chassis 4 channel B22 could be done with off-board heat sinks and a large chassis like one from the modushop.com.  this would be a very challenging chassis build and not one to undertake unless you have a lot of experience with chassis work and the proper tools.  i would recommend a shielded TX.
 
an easier solution would be a 2 chassis design.  the 12x12x3 Par-Metal series will accommodate 4 boards and the stock 1.5" heat sinks, but require terracing the boards with stand-offs and precise chassis work.  it's a tight fit.  
 
personally, a 16x12x3 Par-Metal would be a simpler solution and allow taller heat sinks and the ability to play with the quiescent current bias a bit above 160mA if you wanted.  whether or not to go with 1 or 2 O22s would determine the size of the PS chassis.  

 

[Zashoomin]

Quote:

the amount of experience/chassis work you can do and the quiescent current bias will drive the chassis design.
 
a single chassis 4 channel B22 could be done with off-board heat sinks and a large chassis like one from the modushop.com.  this would be a very challenging chassis build and not one to undertake unless you have a lot of experience with chassis work and the proper tools.  i would recommend a shielded TX.
 
an easier solution would be a 2 chassis design.  the 12x12x3 Par-Metal series will accommodate 4 boards and the stock 1.5" heat sinks, but require terracing the boards with stand-offs and precise chassis work.  it's a tight fit.  
 
personally, a 16x12x3 Par-Metal would be a simpler solution and allow taller heat sinks and the ability to play with the quiescent current bias a bit above 160mA if you wanted.  whether or not to go with 1 or 2 O22s would determine the size of the PS chassis.  

Thank you for helping out. what is the difference between using 1 or 2 O22's and what case would you recommend for that?

 

[DefQon]

1 O22 will be plenty for just driving headphones 2,3 or balanced operations. But if you really need the extra O22 just for kicks or driving speaker loads, then it doesn't hurt to add it in. You can start off with one O22 then add in another one + trafo if really desired.

 

[preproman]

Go with 2 O22s all the way.  Overkill is good..

 

[Zashoomin]

Quote:

Go with 2 O22s all the way.  Overkill is good..

I'm trying to keep the cost down so I think I will stick to one.  But in order to drive audeze lcd 2's and 3's I understand that there would be more power if I had 4 boards instead of say 2 or 3.  Also is it possible to have single ended inputs and outputs with a fully ballanced design?

 

[preproman]

fishski13 can answer that...

 

[sachu]

Quote:

I'm trying to keep the cost down so I think I will stick to one.  But in order to drive audeze lcd 2's and 3's I understand that there would be more power if I had 4 boards instead of say 2 or 3.  Also is it possible to have single ended inputs and outputs with a fully ballanced design?

really it comes down to whether you want a balanced rig or not. If your source is single ended, then keep it simple, build a 2 board, SE B22 running 150mA bias on 2.5 thermalloy heatsinks at 24V rails. THat's plenty of power to drive the LCD2/3s. 
 
As for your question on SE inputs and outputs with a balanced design. yes. No that's possible. See the amb site for a diagram on how to do this. It is all there.

 

[DefQon]

Quote:

Go with 2 O22s all the way.  Overkill is good..

Yeah overkill is good for cost is no object. But his on a budget man. lol
Quote:

really it comes down to whether you want a balanced rig or not. If your source is single ended, then keep it simple, build a 2 board, SE B22 running 150mA bias on 2.5 thermalloy heatsinks at 24V rails. THat's plenty of power to drive the LCD2/3s. 
 
As for your question on SE inputs and outputs with a balanced design. yes. No that's possible. See the amb site for a diagram on how to do this. It is all there.

+1. Indeed, I've built one of each configuration, 2 and 3 channel designs I heard no difference at all. But going from a 2 channel to balanced there was some gains but not night and day difference, so going SE best keep it simple to a 2 channel or so.

 

[fishski13]

on paper, the LCD3 is speced at 91dB/mW and 45ohm impedance.  this means that to achieve 110dB you need a total of 79mW, with approx 1.9Vrms voltage swing and 42mA current delivery.  while i have spent some time in meet conditions with the LCD3 and the LCD2, i can't comment on subject opinions of power requirements.  having "a little" headroom above this is a good thing for quieter mastered recordings and musical peaks.       
 
reducing the O22 rails to 24V isn't a bad idea unless you need enough Vswing to drive the HE-6 or K1000.  this means less power dissipated by the heat sinks and allows you to play around with the quiescent current bias.  i prefer 200mA, but have gone up as high as 250mA or so.  a higher bias means more power in Class A, but my preference isn't due to the fact that my HPs need more power in Class A, but rather the devices themselves sound better with my ancillary gears with the higher bias.  a bias of "only" 80mA may sound better to your ears?  i even prefer my M3 with a bias of 150mA but don't have the heat sinks or TX to go comfortably higher.  both the B22 and M3 use the same output MOSFETs.  YMMV.      

 

[DefQon]

fischki do you have pictures of your 2 channel?

 

[fishski13]

Quote:

fischki do you have pictures of your 2 channel?

 
i have them on my website in the lower right hand corner on the first page with the amber fresnel LED, but basically just the faceplate.  the internals and layout are virtually identical to the other 2 channel B22 with the green LED on my website on the second page under "portfolio", except: the boards are a little more trashed since it's been through numerous mods and rechassis over the past 5 years; the chassis is 3" vs 4" tall; GP SA vs TKD; 1.5" vs. 2.5" heat sinks; 100VA vs 50VA TX; and different tin-platted Belden wire vs. SPC.  the "high ohm" TRS has 100R resistors in series for HPs that need a little extra mid-bass.  the TXs are fully shielded/encapsulated from SumR.

 

[DefQon]

Can't find it. Had the impression yours is a dual mono configuration.

 

[fishski13]

no dual mono. not enough room for the form factor i wanted.  i can send you pics later when i get home from work.