BUILD THREAD - A New Take on the Classic Pass Labs D1 with an ESS Dac - Page 40 - diyAudio
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Old 16th September 2011, 04:13 PM   #391
opc is offline opc  Canada
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That would work perfectly. Even if you have to drop down to 40v rails, there's very little difference between 40V and 45V. You're best to minimize the drop across the regs if you think things are running a little too hot.

Give it a try and see what you get before the regs, then just set the output of the regs a few volts lower.

Regards,
Owen
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Old 16th September 2011, 05:08 PM   #392
qusp is offline qusp  Australia
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and we have another winner!!

yeah Davide, the numbers i did on the sink and my personal experience put your 27 degree ambient temp in the upper range, but still within SOC as long as you think about it wrt the other stuff in the case, ventilation etc.

Last edited by qusp; 16th September 2011 at 05:33 PM.
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Old 17th September 2011, 01:13 AM   #393
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Swapping the taps I have 49.5 V DC in and I set 45Vdc out. That's just perfect. 1 W on the little sink is ok.

I could listen to it on my main system and made some measurements. Well, with my instruments, measurement were boring, there was just nothing. But I found out that I have a problem on the DAC at 192 kHz. I will have a new usb-i2s interface soon and I will compare.

From the listening point of view. Compared to the legato, it's another world, beside the fact that the input is much higher, and I do not run out of juice with my F5 on the audiophile recordings, that are recorder lower then normal rock albums.

I don't think I will feel the need to go dual mono, but I will give it a try.

Thanks,

Davide
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Old 17th September 2011, 01:25 AM   #394
opc is offline opc  Canada
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Hi Davide,

That's great news all around! I didn't realize it was so easy for you to swap taps on the primary, or I would have suggested it earlier.

50V input is pretty much perfect for 45V rails, so you're right where you need to be.

I'm glad you like the way it sounds, you've certainly earned it! It's a really kick-*** I/V stage, and I always enjoy it when people like the way it sounds.

Good work on the assembly, and I'm glad you hung in there through the little ups and downs of getting it just right.

Enjoy

Owen
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Old 17th September 2011, 10:29 AM   #395
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Yes, I'm kind of postponing the problem, but in Europe is pretty easy to get toroids, don't ask me why Japanese don't use them, at least you cannot buy them easily.

I still did not decide what to do with the balanced to unbalanced stage. I have one board nicely boxed that I am using now, and a full kit ready to be assembled.

Basically I have three options:
1) Stay as I am. Hopefully the F5X will arrive soon and I will not need it. When I need it I can use the external unit.
2) Stick the converter in the DAC, in order to have SE out.
3) Stick the converter in the preamp (DCB1) in order to have a balanced input in the pre.

Maybe the latter is the most versatile option. Additionally this would leave me more space in the chassis if I want to experiment with the power supplies of the DAC or of the IV.

I think it was my mistake with the transformers, as I ordered the 50 VA, with the idea bigger is better, but with small current drain the voltage is too high. I should have told Richard to use the bigger core and reduce the regulation. Lesson learned.

For sure this is not a beginner project, both for the SMD part and for the manually needed to assemble the board on the sink.

I ordered the diodes you suggested, but what's the real risk, once the thing is fully assembled and tuned ?

Thanks,

Davide
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Old 17th September 2011, 10:36 AM   #396
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Just one question: if I want to use the spdif isolation transformer for normal spdif in the buffalo input, I think the resistor should not be populated at all, as the termination is already on the board. Is it correct ?

Thanks,

Davide
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Old 17th September 2011, 03:48 PM   #397
qusp is offline qusp  Australia
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no the resistor on the board iv should be populated and just turn the spdif switch on the b2 to off and use D1 and ground rather than spdif and ground on the buffalo. afaik its best to have termination at the end of the cable before the transformer, otherwise the sending end will only see the reflected impedance. I could be wrong there, but thats the way i understand it
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Old 17th September 2011, 03:59 PM   #398
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I'd like to avoid to use D1, so I can devote that to I2S and switch the input via software.

The transformer is 1:1 so should not matter on which side you put it, but in all the reference design is towards the receiving device.


D.
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Old 17th September 2011, 04:28 PM   #399
qusp is offline qusp  Australia
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haha sorry you are right, my utterly non-photgraphic memory is faulty. for some reason i was thinking the resistor was at the input of the schematics i was looking at last night in order to terminate the cable. my comment still holds re D1, but if you have other plans for that pin then sure, if you have to keep the comparator and termination on the buff in place then dont populate the one on the board.
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Old 17th September 2011, 07:52 PM   #400
NicMac is offline NicMac  Italy
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Quote:
Originally Posted by Nikon1975 View Post
From the listening point of view. Compared to the legato, it's another world, beside the fact that the input is much higher, and I do not run out of juice with my F5 on the audiophile recordings, that are recorder lower then normal rock albums.
Davide,
Could you elaborate a bit on your listening experience? Different or better?
Cheers,
Nic
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