BUILD THREAD - A New Take on the Classic Pass Labs D1 with an ESS Dac - Page 60 - diyAudio
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Old 8th May 2013, 12:30 PM   #591
opc is offline opc  Canada
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Quote:
Originally Posted by Rolle View Post
Qusb, Thanks for your comments. Yes you are right the PH regs where getting too warm mounted that way - i have now placed them in upright position.

Reg transformer, I saw OPC suggested Antek AN-0540 which has 40v sec.

I got all hooked up yesterday and are now playing music :-) I can't believe I got all those tiny resisters and caps soldered correctly in first go - I could not have done it without all the guidance and good advice in this thread - thanks a lot
Glad to hear you're up and running!

As qusp mentioned, the Antek transformers tend to sag a little more than others, so you should be fine there. I'm using the same parts and they've been great for the past few years.

It would be worth checking your various rail voltages with a DMM though just to be sure.

Measure the unregulated voltage on the first filter cap and note it down. If it's more than 10V drop across the regs (the difference between your unregulated and regulated rails) you should probably shift some of that dissipation off onto the I/V itself assuming you have capacity in your I/V heatsink.

The sweet spot for this circuit is between 44V and 48V, so try and stay in that range.

The current through each reg is roughly 230mA, so as long as you keep the voltage drop to under 10V you'll be dissipating less than 2.5 watts on those little regulator heatsinks which should be fine.

Enjoy the new I/V, and please do report back when you've done some good listening!

Cheers,
Owen
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Old 8th May 2013, 01:23 PM   #592
Nikitas is offline Nikitas  Greece
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Default balance to SE conversion for the NTD1

I am thinking of building a balance to SE converter for my ntd1, with LME49990s since I have some lying around. At some point I remembered than opc's lpuhp utilizes that.

So is the below schematic (part of opc's lpuhp) correct to be used for this purpose?
I'm thinking of supplying it with 18V "stolen" from the ntd1.

What do you think?
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Old 8th May 2013, 01:29 PM   #593
qusp is offline qusp  Australia
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depends on your caps, the LPUHP in balanced input format has pretty low (lowish) input impedance, so you need reasonable sized caps on the NTD1. myself i'd be building a balanced amp before adding a BAL-SE to the NTD1, but thats just me. seems a waste, may as well have just used the lme49990 as your IV... my prejudice on this matter are fairly well known

Last edited by qusp; 8th May 2013 at 01:33 PM.
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Old 8th May 2013, 01:35 PM   #594
Nikitas is offline Nikitas  Greece
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I hear you, but I already have three amps, all SE input and I wouldn't want to build another one at least for now. I prefer to first build me a dac/iv/buffer.

The goal is to have after the ntd1 a switch which will send the signal to the converter or directly out to xlr connector. This way I will have the option to use any balanced or unbalanced amp.

Could you elaborate about the caps?
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Old 9th May 2013, 08:33 AM   #595
qusp is offline qusp  Australia
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you need to size your output caps and the resulting 3dB point, keeping in mind the input impedance of the LPUHP.

Owen, seems this question comes up quite a bit, I wonder if a suitable discrete BAL-SE stage in keeping with the style of the NTD1 (ie massive overkill) could be devised.
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Old 9th May 2013, 11:14 AM   #596
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For discrete BAL-SE conversion, XCEN and the XCEN-HAGS would seem to be nice choices, though not quite available yet.
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Old 9th May 2013, 11:25 AM   #597
Nikitas is offline Nikitas  Greece
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Those seem great choices, but someone would have to wait for months.

****that doesn't mean I complain, just stating a fact****

Since opc doesn't reply to my emails, I will go for a transformer. Seems to be a faster and less complicated option.
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Old 9th May 2013, 11:32 AM   #598
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I think opc has been moving house and quite busy lately.

I don't see any practical reason to not go for the The Wire BAL-SE / LPUHP input design as you showed above, I'd much prefer that over a transformer personally.
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Old 9th May 2013, 11:43 AM   #599
Nikitas is offline Nikitas  Greece
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Quote:
Originally Posted by qusp View Post
you need to size your output caps and the resulting 3dB point, keeping in mind the input impedance of the LPUHP.
The reason is I want to avoid the above part..
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Old 9th May 2013, 02:00 PM   #600
Rolle is offline Rolle  Denmark
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Originally Posted by opc View Post
Glad to hear you're up and running!

....

Enjoy the new I/V, and please do report back when you've done some good listening!

Cheers,
Owen
Sure will report back after I have listened further. Currently i only have a single ended amp and are tapping signal from 1 phase of the I/V - well aware off the limitations based on your comments earlier in this thread.

I have been using John Broskies unbalancer as I/V and bal/se converter with the Buffalo dac and thinking I could use the bal/se stage (broskie cathode follower BCF PCB and Kit) of the unbalancer board just to see how it sounds with your I/V. The BCF offers high input impedance - so I can get away with lower value coupling capacitors. I took also snapshot of the schematic and have attached it below. I am only wondering about the input cap on the + signal on the BCF - I guess I don't need that - any of you guys have an idea about that?

By the way - I checked voltage before regulator it was only 52v - so regulator only dropping 7v - but thanks for bringing that up
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