DIY Transistor Amp Using NVA Boards

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Paul Barker
Oooo, Roberts Radio's sound nice
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Joined: Mon May 21, 2007 9:42 pm

Re: DIY Transistor Amp Using NVA Boards

Post by Paul Barker » Wed Feb 05, 2020 8:10 am

Cressy Snr wrote:
Thu Jan 23, 2020 4:17 pm
steve s wrote:
Thu Jan 23, 2020 11:21 am
It would be good to hear it Steve, I too have found what I think is a much better amp than the a20, but im sure people will laugh when I say it's built around the tda2030 chip..
I've owned them for a few years, but eventually give them a try a few months ago.. pretty good in my view.

I've been trying to build an off the net circuit, quite unsuccessfully !.. to see if the sound is recreatable.... I think I'm going to end up copying my originals when I get a chance though.

I've been planning a new valve amp and been back and forth deciding which output valve to use... still not really settled on it.. going back to one power supply.. as a tester, but with an unconventional smoothing arrangement as valve amps go.
I have picked a mains transformer with multiple by taps so switching between choke and cap loading will give a wide HT range, I think I may settle on 250vt globe px4s for testers
Let's see..
Wish I’d paid more attention back in 1975; it would have been far easier to learn about transistors then, than now, when I don’t know what day of the week it is half the time :l
I forgot a cousin’s name yesterday trying all evening last night while with someone I needed to tell. The more urgent the need to recover the momentary laps of knowledge the emptier the conscious mind becomes. Just now when I read Your post Steve her name just popped up from the dark emptiness. Always comes when you aren’t in need of it later!
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein

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Ali Tait
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Location: Galashiels

Re: DIY Transistor Amp Using NVA Boards

Post by Ali Tait » Wed Feb 05, 2020 9:27 am

I believe it's called a senior moment. :D

steve s
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Re: DIY Transistor Amp Using NVA Boards

Post by steve s » Wed Feb 05, 2020 6:46 pm

Nice to be of use Paul
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number

kptseng
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Joined: Mon Jun 15, 2020 1:06 pm

Re: DIY Transistor Amp Using NVA Boards

Post by kptseng » Wed Jun 17, 2020 10:56 am

Hi Everyone,

I’ve been reading this for recently and have joined this forum 2 days ago.
Seeing this project getting on well gives me a lot of confidence in modifying my old A60 into something better.

My plan is to use 100W transformer for each input stage and 250W transformer for each output stage.

I’m seriously considering using a LDR attenuator (aka Lightspeed) with a remote controllable digital potentiometer; but seems like the LDR type is only suitable for amp with input impedance no less than 100k. I’ve tried searching for NVA’s input impedance but with no clear answers. Can experienced NVA fans advise me on this?

Once I get this done I’m actually thinking of ripping out my Chord Mojo and incorporate this into the amp as well (of course with a dedicated power supply).

Many thanks in advance

KP

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