A New Take on the Classic Pass Labs D1 with an ESS Dac - Page 27 - diyAudio
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Old 27th September 2010, 03:18 PM   #261
pidesd is offline pidesd  Canada
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hey guys,

what specs should have an output transformer for this I/V?

also i m curious to know which would perform better, caps balanced or Xformer unbalanced.
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Old 27th September 2010, 03:33 PM   #262
qusp is offline qusp  Australia
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errmm good suggestions, but we really dont want to turn this into another thread and start the design all over again. real results from the last schematic are good enough for me and at the boundaries of all but the best test equipment. and the sound is excellent, I just would like something with a more suitable design without so many alterations to fit the current schematic

I would hate for owen to get bombarded with multitudes of different opinions again and decide its too much of a PITA and he cant please everyone, which I could understand, considering he already has a working build. nothing wrong with a bit of feedback, but suggestions to turn it upside down, may not be productive at this juncture

also your calc for caps seem to be completely discounting phase distortion which has effects at up to 10x the corner
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Old 27th September 2010, 03:34 PM   #263
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I'm in for two PCB 4 layers or 2 layers.
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Old 27th September 2010, 03:37 PM   #264
opc is offline opc  Canada
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Hi pidesd,

IMO Balanced with caps is without a question going to be magnitudes better than a transformer coupled variant.

I'm sure others might disagree, but feel that transformers in the signal chain is about the worst thing you could possibly do to your audio. They distort, they have FR anomalies, they're very source and load dependent, they're expensive, bulky, susceptible to magnetic coupling, and just generally a bad idea unless absolutely necessary.

I know there are some people that swear by them, and even some who run their buffalo DACs in voltage mode directly into a transformer, and then rave about the results, but I can assure you they don't work well, and especially not in the setup I just mentioned.

Just my opinion, but I do have measurements to back it up.

Cheers,
Owen
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Old 27th September 2010, 03:42 PM   #265
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I prefer caps vs transformers.
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Old 27th September 2010, 05:00 PM   #266
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Hi Owen

I'd just like to say that the layout in post #250 looks spot on, very tidy. I agree with qusp that you shouldn't get bogged down with too many alterations and adjustments.

Can I ask, have you designed the board so that long pin headers are used to connect I/V board to DAC like TP do?

If so, would it be possible to include these in any component GB's that may happen?

Cheers
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Old 27th September 2010, 05:01 PM   #267
qusp is offline qusp  Australia
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I actually quite liked the sound of them sometimes and ran TX at the output of the buff for quite a while. definitely not the best measuring or linear and while quite easy to listen to, if going for high resolution and low distortion you can forget about it.

seems like an elegant solution due to the low component count, but if you think of the nasties and how long and massive the circuit becomes it becomes not so appealing. bested by a number of other output stages.

that being said, I would love love love to get rid of those caps, which arent exactly pretty either. though what goes there can easily be left up to the individual.

Last edited by qusp; 27th September 2010 at 05:05 PM.
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Old 27th September 2010, 07:19 PM   #268
CeeVee is offline CeeVee  Portugal
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Hi Guys,

Some more input on pcb layout.
I do not want to look as unapreciative of opc's fantastic work, this is just an atempt to do teamwork.

Here is a quick 3D rendering of the major components on opc's initial layout.

3D gives a better "feel" for final product, i think.
Attached Images
File Type: jpg OPC Proposal 1small.jpg (38.1 KB, 601 views)
File Type: jpg OPC Proposal 1-2small.jpg (73.1 KB, 596 views)

Last edited by CeeVee; 27th September 2010 at 07:22 PM.
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Old 27th September 2010, 07:26 PM   #269
CeeVee is offline CeeVee  Portugal
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Ilustrating my ealier post on an alternative layout:

This one permits components on both sides of the pcb and leaves more space for coupling caps.

It does mean that DAC is facing down ...but objective is not to look at DAC i think...it's the music

note: big heatsink is generic, this is just to portray the idea.
Attached Images
File Type: jpg heatsink2small.jpg (39.8 KB, 588 views)
File Type: jpg heatsink3small.jpg (97.5 KB, 582 views)
File Type: jpg heatsink4small.jpg (55.8 KB, 560 views)

Last edited by CeeVee; 27th September 2010 at 07:30 PM.
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Old 27th September 2010, 07:28 PM   #270
CeeVee is offline CeeVee  Portugal
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front on view...
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