High Performance WM8741 Upsampling DAC New Version build thread (show 'n tell too) - Page 7 - diyAudio
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Old 9th February 2012, 11:10 PM   #61
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Schematic?
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Old 10th February 2012, 12:37 PM   #62
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Found it.

Stupid junk mail filter.

Last edited by TheGimp; 10th February 2012 at 12:50 PM.
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Old 10th February 2012, 12:55 PM   #63
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Originally Posted by merlin2069er View Post
A lot easier with low temp solder, at least as far as wicking bridges/cleanup, much less chance to overheat the chip, but it won't pass Mil spec for submarine use.
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Old 10th February 2012, 07:02 PM   #64
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Looking at the TI TCM2702PJT, there are two versions available from Mouser.

595-PCM2707PJT @$10.13 and 595-PCM2707PJTRG4 @ $6.80

I don't see any difference in the data sheet, and the only difference in the Mouser description is that the first is delivered in trays, and the second is cut tape and reel.

Does anyone know of any other difference (performance)?

It appears to me that both are comparable so the cut T&R is a better buy.
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Old 10th February 2012, 07:09 PM   #65
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Originally Posted by pinnocchio View Post
Looks pretty simple to me. However, that Lundahl LL1674 is on the expensive side. I paid 85$ per 1545A and never got to use them... It is a shame!
I've used these for isolation for AudioTester and they work quite well.

At $10.23 each they might be worth a try.

EDCOR - WSM10K/10K
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Old 11th February 2012, 04:24 AM   #66
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Originally Posted by TheGimp View Post
I've used these for isolation for AudioTester and they work quite well.

At $10.23 each they might be worth a try.

EDCOR - WSM10K/10K
Have any before after FFT shots as far as increase in harmonic distortion? Was the frequency response flat?

There is also a identical edcore one model up (bigger core) with more inductance on the primary for a few dollars more. The plots on the webpage show moredistortion but this could just be be cause the bigger transformer was testing with a larger input.
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Old 11th February 2012, 04:47 AM   #67
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I don't have any plots on hand, but I can put it back together and run it. Hopefully this weekend.

I've got two set up with one on the output from the sound card and one on the input. I'll just jumper them in to out and run a plot. (I have to clean off the workbench first so it might be late tomorrow or Sunday.
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Old 11th February 2012, 04:55 AM   #68
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Thanks, usually one would pay a premium for nickel core for little transformers but the M6 in the edcors may be fine.
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Old 12th February 2012, 12:32 AM   #69
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I had to zip the pdf file to upload it.

Looks like I need to shield the transformers.
Attached Files
File Type: zip Xfmr test.zip (308.1 KB, 41 views)
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Old 12th February 2012, 02:37 AM   #70
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I dug out some old tubes I got from my dad (we used to fly RC airplanes in the 60s).

They are 1AG4 pentodes designed to run off batteries. Filaments (not heaters) are designed for 1.25V, Plate (anode) curves are given for 90V. These are output Pentodes which are spec'd at pretty high THD in that mode (35mW at 12%thd) , however triode strapped data is given in some data sheets and they look pretty linear. If lightly loaded, they might work well.

I'm thinking of leaving out the op amps, and running a vacuum tube Long Tail Pair with current source in the tail, then drive one of these transformers for the output.
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