A New Take on the Classic Pass Labs D1 with an ESS Dac - Page 145 - diyAudio
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Old 28th November 2012, 12:35 PM   #1441
opc is offline opc  Canada
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Quote:
Originally Posted by Magsy View Post
Can someone confirm the current draw per channel please?

I read early in the thread a few times 115ma per +/- leg, 230ma per channel or ~460ma per 'board'.
I specced and ordered some expensive custom transformers based on that but reading the thread yet another time I see OPC referring to 230ma per leg later on which is going to mess me right up

I'm not planning on using the onboard regs but Salas shunts.
Hi Magsy,

Your original value of 115mA per leg is correct. There are two legs per channel meaning each channel draws 230mA of current all the time.

The supplies are dual mono, meaning each channel has its own regulators and bridges.

Following that, you can say that each regulator feeds one full channel, or two legs, with either positive or negative voltage. As a result, roughly 230mA flows through each regulator, so each secondary of the transformer needs to be able to supply at least that amount continuously.

If you happen to be running your ES9018 in full mono mode, then you have the luxury of double the output current from the DAC. In that case, your best move is to reduce the resistor values by half, which increases the current by a factor of two, and takes performance up with it. I have referenced that in the past, so maybe that is where you heard the 230mA number.

Hopefully you got the right transformer!

Cheers,
Owen
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Old 28th November 2012, 02:21 PM   #1442
Magsy is offline Magsy  United Kingdom
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Phew Thanks for the clear explanation!

I bought two 40va 2x36v trafos, so 560ma per secondary....plenty but I am going to use Salas shunts all round.

Didn't realize until last night that you should to de-rate the secondary DC current by ~1.6-1.8x to allow for the FWB rectifier followed by a cap.

1 leg = 1 shunt = 1 secondary | 115ma + 115ma (ccs/shunt load) = 230ma

1X secondary = 560ma / 1.8 = 311ma available

Good news, just the heat to deal with now
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Old 28th November 2012, 03:08 PM   #1443
qusp is offline qusp  Australia
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yeah thats a 250W dac when you halve the resistors, not worth it IMO for what 1-2dB on top of an already ~-116dB THD+N in mono mode

Last edited by qusp; 28th November 2012 at 03:13 PM.
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Old 28th November 2012, 03:23 PM   #1444
opc is offline opc  Canada
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Yeah... it's a bit of a moot point anyhow since I don't think anyone is running a dual mono setup.

Hopefully people understand that if they do want a dual mono setup, they still only need one NTD1 PCB, to which they need to mount two Buffalo II or III boards. The NTD1 is already dual mono by nature, and does not require any changes. Using two NTD1 boards leaves you with 4 balanced outputs, which is not true dual mono.

The only real advantage to running the ES9018 in mono mode is the doubling of the output current. There is no other benefit, especially not in terms of stereo separation.

As for dropping the resistor values, again it's not something I anticipate most people will do unless they really know what they're doing. It would require also dropping the voltage down to keep the power dissipation in check, and it also reduces the gain of the circuit.

Cheers,
Owen
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Old 28th November 2012, 03:40 PM   #1445
qusp is offline qusp  Australia
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yeah I did the calcs for the lower voltage, but then you need to make other changes if you want to keep the current up above stock, there are a couple running 2 boards, I havent asked everyones motivations. I have enough unpaid psuedo consultation via email and PM as it is.

it depends on how you are running the mono mode in the ESS, theres 3 different mono modes and you can run with 2 boards, which although larger and more expensive is somewhat neater than trying to piggyback 2 dacs to a single NTD1, which would make for a bit of a mess and longer current connections, which could easily offset any advantage.

its no different to how people are running dual mono with 2 IVY, or 2 Xxx you need to map the dac channels appropriately. so people running dual mono with any of the twisted pear stuff will not change anything when running 2 x NTD1.

i'm running 2, but for 4 channel. which is the advantage of running with 2 boards, you can run dual mono, or you can make a 2 way crossover, either digitally, or by installing active or passive analogue filters in the analogue stages

Last edited by qusp; 28th November 2012 at 03:46 PM.
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Old 28th November 2012, 05:12 PM   #1446
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To all US builders that paid up for shipping - thanks! For those of you that haven't... well? :-)
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Old 29th November 2012, 12:09 AM   #1447
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Quote:
Originally Posted by opc View Post

Hopefully people understand that if they do want a dual mono setup, they still only need one NTD1 PCB, to which they need to mount two Buffalo II or III boards. The NTD1 is already dual mono by nature, and does not require any changes. Using two NTD1 boards leaves you with 4 balanced outputs, which is not true dual mono.

The only real advantage to running the ES9018 in mono mode is the doubling of the output current. There is no other benefit, especially not in terms of stereo separation.

Cheers,
Owen
I am the one don't know and have ordered two sets of NTD1, I now have one set of spare
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Old 29th November 2012, 12:35 AM   #1448
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Hi,

Sorry, I am a bit lost in this big thread,
I tried to find the schematics of the boards your are talking about but I didn't found it.
I am looking for a good IV stage for my DAC, initial thread was about D1B1 IV stage,
I don't know if it will work at the output of my PCM1704 DAC and if there are PCB board available of it?
Please give me some details about it,

Thanks, :-)
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Old 29th November 2012, 12:43 AM   #1449
qusp is offline qusp  Australia
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cocojazzsta
no there are no boards left and no its not designed for 1704, like the thread subject says... its for ESS. its a pretty highly modified version, runs at double the voltage at least, doesnt have the buffer etc.

bigpandahk:

haha actually thats not a bad idea is it? having a spare I mean.

no but really it will be neater IMO, the BIII is a pretty sprawling design, it will probably be neater having 2, I dont think it would be very easy to stack them efficiently and it would have ruled you out for the GBs as you would pay full single piece price for everything.

it wont leave you with 4 balanced outputs if you use the same setup as you would with IVY you will have 2 channel.

Last edited by qusp; 29th November 2012 at 12:47 AM.
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Old 29th November 2012, 02:57 AM   #1450
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Originally Posted by Emphrygian View Post
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