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Buffalo II

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Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
qusp said:
I got the COD running portable BTW, sounds really nice and i'm surprised it doesnt get more attention. only running it single ended though as dac only because I started the research for a decent volume control then you announced the b32v2 and this made the volumite a possibility.

also thanks for the info, that will come in quite handy
Click to expand...

Your welcome.

Here is my recommendation. Use a split supply. Tie VOCM to 0V and bypass at the supply pins well (to 0v thus the need for split supplies). The other possibility while it will work could pose other challenges you may not be wanting to tackle.

Maintaining the batteries charge is up to you. I don't have a great solution for that. :)

I fully agree about the COD. It actually measures nearly as well as the Buffalo when used with the IVY-III.

Cheers!
Russ
 
qusp

qusp

Member
Joined 2009
thanks yeah I have some rail splitters too, need to 'ground' the case somehow really, i'm up for challenges though, if theres a payoff at the end its all good with me. I have a massive pile of schematics I need to start bread boarding soon, will probably use an addition or or just a similar circuit to the charge circuit/rail splitter for the PPAv2 on tangents site. contacted battery world about a couple of custom battery pacs (yes split) a couple of weeks ago, yet to hear back from them yet.

doesnt surprise me about the COD, finished a second one yesterday too so wil platy around with some output stages while I wait for the b32v2. currently enamored with a mixed feedback schematic by jung that uses output transformers inside the feedback loop and takes the best of both worlds.

oh and as far as bypassing, no need to worry about tghat, if anything i'll probably get a bit carried away with it. got some nice wima and evox/rifa SMD PPS and PET films I was planning on using for everything although I also have enough ceramics i'm keen on doing the whole thing with films.
 
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G

glt

Member
Joined 2004
diyaudio.com/forums/showthread.php?s=&threadid=140669
Russ White said:
Sorry, but this is not correct.

The benefit of current mode (ultra low impedance) is that the voltage the DAC outputs see does not change with current, it does not modulate, so the outputs of the DAC stay where they always are. They always see the same bias voltage. This is why performance is better. It also makes it so that thermal effects are spread evenly.

Cheers!
Russ
Click to expand...

Russ, that makes a lot of sense now. I was trying to make sense of footnote 16 of the white paper where it says current mode "cancels" an on chip voltage coefficient. I understood that as for example the on chip resistor has positive voltage coefficient, then the off chip resistors would have negative voltage coefficient and thus they would cancel. But if in current mode, the voltage stays constant, then there is no effect of voltage coefficient on the on chip resistors
 
NicMac

NicMac

Member
Joined 2009
Paid Member
I don't think anybody besides Russ and Brian have listened to the Buff II yet so your question is a bit difficult to answer. Certainly the Buff II is way more tweaking friendly than B32S and the new IVY III may also be very interesting.
 
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Duffy Moon

Duffy Moon

Member
Joined 2008
HaLo6 said:
Has anyone compared the B32 to the BII? I wouldn't imagine that there shouldnt really be a need to switch is there? Is the performance delta between the two significant?
Click to expand...

I don't think anyone has a BII yet (apart from Russ & Brian) to make the comparison.
Personally, if I had a B32 already I don't think I'd bother switching.

If you have money burning a hole in your pocket, I'm an impoverished student so you could just send it to me :D
 
W

Woodenhead

Member
Joined 2008
HaLo6 said:
Has anyone compared the B32 to the BII? I wouldn't imagine that there shouldnt really be a need to switch is there? Is the performance delta between the two significant?
Click to expand...

Given the improved dac supplies on-board the new BII, I think it will sound better stock than the B32s. This is just a guess on my part. If you have a B32s, and want to gain a similar level of improvement, have a look at the Buffalo Tweaking thread in the digital line level, which has some excellent suggestions (later in the thread) from a few people, regarding modification of the dac/xo supplies.

Best upgrade for myself have been moving to shunt supplies for the IVY on my B32s.
 
C

Crafty

Member
Joined 2008
Buff 2 Dimensions & Power

Hi Russ / Brian,

I am looking fwd to the arrival of my Buff2 kit with dual mono placids for VA.

I am about to order the casework for my build and have a couple of questions:

) What's the total height of the stacked assembly of Buff2 / IVY3 including all standoffs?

) I read a post somewhere that reccomended setting the VD placid for 350ma @ 5.5V Is that correct?

The reason i ask is i am keen to get all of this into a 1U case, i did this with Buff32S by changing the heatsinks on the placid's to 1" parts. I am concerned that with a higher current demand for VD i wont be able to get away with 1" heatsinks? If its a no go i will look into a 2U solution?

) Any benefit to housing the Placid's and transformers in a seperate enclosure or could this potentially be worse?

Thanks,

Luke
 
G

glt

Member
Joined 2004
diyaudio.com/forums/showthread.php?s=&threadid=140669
Crafty said:
Hi Russ / Brian,

...
The reason i ask is i am keen to get all of this into a 1U case, i did this with Buff32S by changing the heatsinks on the placid's to 1" parts. I am concerned that with a higher current demand for VD i wont be able to get away with 1" heatsinks? If its a no go i will look into a 2U solution?
...

Luke
Click to expand...

You could install the power transistors to the case like this:
4130609151_e9945790f0_o.jpg
 
BrianDonegan

BrianDonegan

Member
Joined 2004
twistedpearaudio.com
Any benefit to housing the Placid's and transformers in a seperate enclosure or could this potentially be worse?
Click to expand...

Some people like doing this, but I would recommend against it.

You could install the power transistors to the case like this:
Click to expand...

...what he said. We designed the Placid specifically for this application in short cases. Aluminum cases are MUCH better for this type of application then steel, as aluminum will dissipate the heat faster (steel gets hot and stays hot).
 
M

Marek

Member
Joined 2003
I have a question about current output mode. It was mentioned that Sabre DAC switch to current mode with load less than ~700ohm.
What total current DAC can deliver on output? (it will be sum of 4 internal DACs currents per channel).
I'm going to use Lundahl LL1517 output transformer as output stage with BII and I wonder if I can do this without any aditional transistor buffers because primary winding inductance is about 0,6H, and each primary has ~10ohm DCR.

Thanks
Marek
 
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