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DIY Amplifier - Naim NAP250

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DIY Amplifier - Naim NAP250

Post by sean1981 on Wed Oct 24, 2018 4:11 am

DIY amplifier  - 
Naim NAP250 

Price: RM1,300
Condition: 9/10

80 Watts @ 8 Ohm

Dual mono design - Input (pre amp part) section using Clone Naim 250 Power amp circuit 
Output transistor using legendary ONs (formally a.k.a Motorola) power transistor
280W toroidal transformer which customized to suit 220-230V malaysia voltage.

Whatapps: 016-338 6465 for more details or audition can be arrange.


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Re: DIY Amplifier - Naim NAP250

Post by BruceWayne on Wed Oct 24, 2018 8:35 am

The input preamp section is using a power amp circuit. Preamp and power amp are different animals doing different function and driving different animals. Good luck

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Re: DIY Amplifier - Naim NAP250

Post by olive on Thu Oct 25, 2018 1:12 am

BruceWayne wrote:The input preamp section is using a power amp circuit. Preamp and power amp are different animals doing different function and driving different animals. Good luck

Besides the actual Nap250 unit using 650VA transformer.These clone unit was powered by 280VA transformer it is like a Ferrari car fitted with Proton engine.Race track car with restricted power.May be it is underrated?

Krell KSA 250 fitted with 4500VA gigantic transformer ,only made 500W/ch (4ohms).
Naim Nap250 made 125W(4ohm).That also means Naim is  3.5x more power efficient then Krell 250.

if Clone Nap250 made 125W(4ohm). That also means clone is  2.3x more power efficient then Naim Nap250.And it is 4x cheaper. Best Bang for money.Best buy audio equipment in this forum.

other facts
at 8 Ohms load base on known claimed power
Naim nap250  70w
Clone nap250 80W
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Re: DIY Amplifier - Naim NAP250

Post by BruceWayne on Thu Oct 25, 2018 5:15 am

A preamp provides high voltage gain from the low level input signal to a level suitable for the low impedance speakers. But it has little current gain to drive the speakers. That’s where the poweramp comes in by providing the high current needed to maintain the voltage to drive the speakers. Basic ohm’s law. So what i am saying is that to use a poweramp circuit for a preamp job must be new electronics which we have not been taught before. Maybe the designer can enlighten us or just pure BS

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Re: DIY Amplifier - Naim NAP250

Post by olive on Thu Oct 25, 2018 8:32 am

BruceWayne wrote:A preamp provides high voltage gain from the low level input signal to a level suitable for the low impedance speakers. But it has little current gain to drive the speakers. That’s where the poweramp comes in by providing the high current needed to maintain the voltage to drive the speakers. Basic ohm’s law. So what i am saying is that to use a poweramp circuit for a preamp job must be new electronics which we have not been taught before. Maybe the designer can enlighten us or just pure BS

Without active Preamp, The volume control knob (Resistive)may be acting as passive Preamp ,least signal contamination ,this is a brilliant cost down approach(for non audiophile listening) ,however without active preamp the clone 250 may not able to play loud nor music may suffer bit lost in dynamics.
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Re: DIY Amplifier - Naim NAP250

Post by sean1981 on Thu Nov 15, 2018 5:28 am

up

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