Search found 11 matches

by kptseng
Sun Aug 30, 2020 9:04 am
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 185969

Re: DIY Transistor Amp Using NVA Boards

Hi Nick, thank you so much!!

I think I’ve got a much better understanding than before.

Saw this discussion on DIYaudio as well https://www.diyaudio.com/forums/power-s ... upply.html

Cheers
by kptseng
Fri Aug 28, 2020 4:05 pm
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 185969

Re: DIY Transistor Amp Using NVA Boards

Thank you Nick, learn something new again.

You mentioned about drawing 100mA, but for driving the output stage would it be too low?
If I am not wrong NVA's quiescent current is approx 500~700mA.

Thanks.
by kptseng
Fri Aug 28, 2020 5:40 am
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 185969

Re: DIY Transistor Amp Using NVA Boards

Nick wrote: Thu Aug 27, 2020 4:49 pm Across the C, so it provides a guaranteed load for the supply to keep it in choke input. Myself I would not bother and use a regulator, or just use the amps as they were.
Thanks Nick, but pardon my ignorance, is the resistor parallel to ground at C or is it in series from C to output?
by kptseng
Thu Aug 27, 2020 4:25 pm
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 185969

Re: DIY Transistor Amp Using NVA Boards

Nick wrote: Thu Aug 27, 2020 2:12 pm Pk, so 300mH 1A makes more sense, so then you need to draw mor than 100ma at all times. So 240R 10W resistor would do the job. But that will get hot as its dissipating 4W or so.
Thank you Nick, but where do I place the 240R resistor? After the L and before the C?
by kptseng
Thu Aug 27, 2020 1:57 pm
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 185969

Re: DIY Transistor Amp Using NVA Boards

ed wrote: Thu Aug 27, 2020 12:11 pm
kptseng wrote: Thu Aug 27, 2020 11:07 am

My plan is to have 30H/10Amp choke,
??? wow, how big is it?
Opppsssss sorry, I got it wrong. It’s only 300mH 1A....... :-(
by kptseng
Thu Aug 27, 2020 11:07 am
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 185969

Re: DIY Transistor Amp Using NVA Boards

If you are using choke input make sure you are pulling enough current for your choke inductance. Hi Nick, I read about the need to have enough current for the LC filter to work, but I’m not sure what I need to do to ensure that. My plan is to have 30H/10Amp choke, followed by 2x10,000uF for each ra...
by kptseng
Wed Aug 26, 2020 1:41 pm
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 185969

Re: DIY Transistor Amp Using NVA Boards

Thank you Stu, Nick and Rowuk for your input. Power supply will be my first priority and will try out both regulated and unregulated power supply for the input stage, output stage will be fed with unregulated ones. We agree that Richard had designed the circuit so well, which is why we (NVA fans) lo...
by kptseng
Sun Aug 23, 2020 5:00 pm
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 185969

Re: DIY Transistor Amp Using NVA Boards

Hi Stu, For the regulators, I am looking at one of those from Teddy Pardo or this one (https://diyaudiostore.com/products/super-regulator). I'm planning to use LCC after rectifiers, the L before C would not give the peak voltage of 50vdc but around 90% of it so I'm having around 44vdc on my paper fo...
by kptseng
Sun Aug 23, 2020 10:11 am
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 185969

Re: DIY Transistor Amp Using NVA Boards

Thank you Karatestu for the very useful information and sharing you experience. Yes, 47kohm input impedance would be ok for the Lightspeed but while the circuit for LDR volume control is simple, finding 2 matching pairs of LDR will be challenging for me, there is no kits available and I can only fin...
by kptseng
Tue Aug 18, 2020 7:26 am
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 185969

Re: DIY Transistor Amp Using NVA Boards

Just a thought....... I can see that the A80 runs on 2 separate power supplies for the input and output stages. I’ve read the write up about PSU on TNT-audio and seems like a regulated power supply for the input stage would benefit greatly while the output stage should be running on unregulated one....
by kptseng
Wed Jun 17, 2020 10:56 am
Forum: Solid State
Topic: DIY Transistor Amp Using NVA Boards
Replies: 435
Views: 185969

Re: DIY Transistor Amp Using NVA Boards

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. ...