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Old 29th November 2017, 04:09 AM   #141
Destroyer OS is offline Destroyer OS
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Quote:
Originally Posted by pistollero View Post
The heatsink get a bit hot after a few hours of playing...
But i think its normal..right?
Well that just means it is working. As long as you're keeping decently under 70*C then everything is fine. If not you may need more airflow or a larger heatsink. Also, you could have some difficult to drive speakers which may ask more, which will make it operate warmer. Again it's no big deal so long as you're keeping it below 70*C.
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Old 29th November 2017, 08:07 AM   #142
pistollero is offline pistollero  Portugal
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Originally Posted by Destroyer OS View Post
The transformer, if you're using the Hammond 185, doesn't let as much noise through because it has higher loss in the RF range, so the lower voltage noise just doens't make it. So it can still get noise from the AC line going into it, but it transfers less than a toroid without a shield between the primary and secondary (and maybe still better than one with a shield, I don't know for sure).

The transformer doesn't emit RFI, but it does have a field that extends from it - which is comprised of 60hz. The field is there because it's what actually transfers power from one winding to the other, as the wires are not actually touching.

The boards themselves are going to get RFI from the air, since they are not in a metal, grounded, enclosure. But they are very specifically designed to reduce the amount that makes it to the signal. For example noise that does get in from the air or power is attenuated by the capacitors that are on a low inductance set of copper pours. As in they don't have traces, they have low inductance wide areas. Furthermore the section on the amplifier board that regulated voltage also rejects a lot of noise. Explaining that is a bit more complicated, but essentially to the circuit it looks like a big capacitor that doesn't like to feed noise through to the amplifier.

Neither board transmits much of anything. The amplifier board will have the largest fields from the speaker outputs if the wires are not twisted, because higher AC power will be going through them compared to the signal input which has small fields (real nice and small if they are twisted).

It's a good idea not to mix fields, which is why the layouts I've commended do a nice job of keeping wires separate, and keeping the transformers from being next to the amp board itself.
Thank you very much for your explanation.
It is much clear to me now.
How big is the field of the transformer in inches?
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Old 29th November 2017, 08:16 AM   #143
pistollero is offline pistollero  Portugal
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Quote:
Originally Posted by Destroyer OS View Post
Well that just means it is working. As long as you're keeping decently under 70*C then everything is fine. If not you may need more airflow or a larger heatsink. Also, you could have some difficult to drive speakers which may ask more, which will make it operate warmer. Again it's no big deal so long as you're keeping it below 70*C.
It is bellow 70 degrees for shure. It gets warmer if the volume from the dac is louder. On lower volumes is always cold.
My speakers are jbl 3 way monitors 8ohlm.
The sound of the amp is very good. I have been switching input caps. And they all sound different.
Till now i used:
Audyn cap qs6 -2.2uf
Jantzen superior z -2.2uf
Russian ft3 -1.5uf
Wima mkp10- 2.2uf

Is there any benefit of using more than 2.2uf?

Regards
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Old 29th November 2017, 11:18 AM   #144
Destroyer OS is offline Destroyer OS
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No, the corner frequency of 1.5uf is something like 4hz, and 2.2uf is lower. The reason for bigger capacitors is to have a lower corner frequency so you don't get bass roll off. 1uf had bass roll off, despite the corner frequency being a bit below 10hz.

I don't know the transformer field size in inches. There may be a way to approximate it but I'm not really acquainted. Sometimes you can hear it and wave the transformer back and forth from the signal lines to get an idea. But my approach is to just find ways to shield it if I'm worried or having problems. I'm not about to build an enclosure large enough to physically distance everything to guarantee they don't interact in the least.
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Old 6th December 2017, 01:32 AM   #145
Paul Hirst is offline Paul Hirst  Canada
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The D45H11G are back in stock at mouser.

Paul
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