NVA Passive preamp output voltage

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Copperblue
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NVA Passive preamp output voltage

Unread post by Copperblue »

If I connected a source with a 2.1V output into an NVA P50 preamp with a 10k volume pot, what would be the resulting voltage output into the power amp?

Also, would the output be ok into a power amp with a 20k input impedance- in terms of gain / volume etc?

Thanks in advance
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Re: NVA Passive preamp output voltage

Unread post by karatestu »

Copperblue wrote: Sun Aug 08, 2021 7:21 am If I connected a source with a 2.1V output into an NVA P50 preamp with a 10k volume pot, what would be the resulting voltage output into the power amp?

Also, would the output be ok into a power amp with a 20k input impedance- in terms of gain / volume etc?

Thanks in advance
The volume pot is merely a potential divider and so the voltage seen by the power amp depends on the position of the volume control ie anywhere between 0V and 2.1V.

The input impedance of the power amp has nothing to do with the gain AFAIK. What you need to know is the input sensitivity of the power amp (input voltage required to produce the amplifiers full output) The lower the input sensitivity figure the higher the gain. Average gain seems to be around 28 - 30dB. I believe RD designed in more than this to compensate for not having any gain in the preamp.
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Copperblue (Sun Aug 08, 2021 10:04 am)
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Re: NVA Passive preamp output voltage

Unread post by Copperblue »

karatestu wrote: Sun Aug 08, 2021 9:12 am
Copperblue wrote: Sun Aug 08, 2021 7:21 am If I connected a source with a 2.1V output into an NVA P50 preamp with a 10k volume pot, what would be the resulting voltage output into the power amp?

Also, would the output be ok into a power amp with a 20k input impedance- in terms of gain / volume etc?

Thanks in advance
The volume pot is merely a potential divider and so the voltage seen by the power amp depends on the position of the volume control ie anywhere between 0V and 2.1V.

The input impedance of the power amp has nothing to do with the gain AFAIK. What you need to know is the input sensitivity of the power amp (input voltage required to produce the amplifiers full output) The lower the input sensitivity figure the higher the gain. Average gain seems to be around 28 - 30dB. I believe RD designed in more than this to compensate for not having any gain in the preamp.
Many thanks

Gain of the power amp is quoted at 24db, 1.4V sensitivity
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Re: NVA Passive preamp output voltage

Unread post by karatestu »

Copperblue wrote: Sun Aug 08, 2021 9:30 am
karatestu wrote: Sun Aug 08, 2021 9:12 am
Copperblue wrote: Sun Aug 08, 2021 7:21 am If I connected a source with a 2.1V output into an NVA P50 preamp with a 10k volume pot, what would be the resulting voltage output into the power amp?

Also, would the output be ok into a power amp with a 20k input impedance- in terms of gain / volume etc?

Thanks in advance
The volume pot is merely a potential divider and so the voltage seen by the power amp depends on the position of the volume control ie anywhere between 0V and 2.1V.

The input impedance of the power amp has nothing to do with the gain AFAIK. What you need to know is the input sensitivity of the power amp (input voltage required to produce the amplifiers full output) The lower the input sensitivity figure the higher the gain. Average gain seems to be around 28 - 30dB. I believe RD designed in more than this to compensate for not having any gain in the preamp.
Many thanks

Gain of the power amp is quoted at 24db, 1.4V sensitivity
That is quite a low gain but you should be OK with 2.1V source voltage. In fact it could be better than a high gain situation. You will use more of the volume control's travel which can be a good thing. Also I believe lower amplifier gain can bring benefits such as lower circuit noise.

What speakers do you use and how sensitive are they ? How big is your room and what levelof volume do you generally listen at ?
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Re: NVA Passive preamp output voltage

Unread post by karatestu »

I should have read your signature :roll: Audio note rate your speakers at 90dB so will be fine although manufacturers are known to tell porkies when it comes to specs.
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Re: NVA Passive preamp output voltage

Unread post by Copperblue »

Actually this application is a bit different. I have a spare P50 amplifier that is going to be used in an experiment with a Naim Nap160 - which has been modified slightly to accept a standard preamp via RCA’s. Back in the day the Nap160 was by far my favourite Naim amplifier and it would be nice to try this but in a way I am hoping could build on the strengths of the power amp but combing it with the clarity of a passive preamp.
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Re: NVA Passive preamp output voltage

Unread post by Copperblue »

This will be used exclusively with digital sources btw with high outputs, so from a gain perspective I think it should work and thanks to @Karatestu for your feedback
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karatestu (Sun Aug 08, 2021 10:15 am)
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Re: NVA Passive preamp output voltage

Unread post by karatestu »

Copperblue wrote: Sun Aug 08, 2021 9:57 am Actually this application is a bit different. I have a spare P50 amplifier that is going to be used in an experiment with a Naim Nap160 - which has been modified slightly to accept a standard preamp via RCA’s. Back in the day the Nap160 was by far my favourite Naim amplifier and it would be nice to try this but in a way I am hoping could build on the strengths of the power amp but combing it with the clarity of a passive preamp.
Ooo, Naim amps. I agree, the 160 is the best naim amp I have heard but I have never heard the original nap200.

Many don't like passive pre's with naim amps but I eventually ended up preferring a passive with my Avondale NCC200 amps which are in essence the same circuit but refined a little..

Hope it works out for you. Don't sell the 160, it is the gem of the naim range.
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Re: NVA Passive preamp output voltage

Unread post by Copperblue »

Thanks.

Once I get it up and running (which might be a while yet) I will post some feedback.
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karatestu (Sun Aug 08, 2021 11:22 am)
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