Building a DIY amp with NVA amplifier boards

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Dr Bunsen Honeydew
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Re: Building a DIY amp with NVA amplifier boards

Unread post by Dr Bunsen Honeydew » Sat Sep 15, 2018 11:50 am

Class II 0v floats.

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karatestu
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu » Sat Sep 15, 2018 12:03 pm

I like the idea of it floating. One less connection to the outside world and who knows what crap is riding on the 0V mains. Only thing I have connected to mains safety earth now are the electrostatic shields between primary and secondary windings of my transformers.

That has given me another idea. Connect and disconnect the electrostatic shields whilst listening to music. See if I can actually hear any difference .
Naim, Linn & Harbeth fanboy

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karatestu
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu » Thu Sep 27, 2018 4:32 pm

Up until now I have been powering the LTP and VAS sections from one transformer and the driver and output transistors from another (that is how Avondale split the power rail).

Today I have decided to include the drivers on the LTP and VAS psu. So the output transistors have the big transformer all to themselves. I have only done it to one of the mono blocs - the one that was still humming. I had not copied the wiring over from the silent amp yet so using the old wiring layout.

Well blow me. Hum reduced. Go figure.
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Lurcher300b
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Re: Building a DIY amp with NVA amplifier boards

Unread post by Lurcher300b » Thu Sep 27, 2018 5:02 pm

Go figure.
I would expect that. I assume the driver is not taking a huge amount of current, so the ripple on the driver rails will be reduced if its only powering the LTP and VAS.

Only thing that would worry me a little is the sequencing. If they are all from the same supply, they will all either have or have not power. The supply now to the VAS + driver + LTP will stay active for longer on power down as they are using less current, I don't know if any operating limits may be exceeded if the driver is powered and the output stage not. Only Richard could answer that.

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karatestu
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu » Thu Sep 27, 2018 5:10 pm

Lurcher300b wrote:
Thu Sep 27, 2018 5:02 pm
Go figure.
I would expect that. I assume the driver is not taking a huge amount of current, so the ripple on the driver rails will be reduced if its only powering the LTP and VAS.

Only thing that would worry me a little is the sequencing. If they are all from the same supply, they will all either have or have not power. The supply now to the VAS + driver + LTP will stay active for longer on power down as they are using less current, I don't know if any operating limits may be exceeded if the driver is powered and the output stage not. Only Richard could answer that.
Thanks for your response nick.

Sequencing on power down. Never would have thought of that. Dare not turn them off now :grin: Only kidding. I have powered the unit down but only once after checking offset etc and plugging input in.

As Richard has said earlier, its a miracle nowt has blown up yet :lol:
Naim, Linn & Harbeth fanboy

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Dr Bunsen Honeydew
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Re: Building a DIY amp with NVA amplifier boards

Unread post by Dr Bunsen Honeydew » Thu Sep 27, 2018 6:15 pm

Lurcher300b wrote:
Thu Sep 27, 2018 5:02 pm
Go figure.
I would expect that. I assume the driver is not taking a huge amount of current, so the ripple on the driver rails will be reduced if its only powering the LTP and VAS.

Only thing that would worry me a little is the sequencing. If they are all from the same supply, they will all either have or have not power. The supply now to the VAS + driver + LTP will stay active for longer on power down as they are using less current, I don't know if any operating limits may be exceeded if the driver is powered and the output stage not. Only Richard could answer that.
No problem.

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karatestu
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Re: Building a DIY amp with NVA amplifier boards

Unread post by karatestu » Thu Sep 27, 2018 7:36 pm

:dance:
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