Search found 618 matches

by Lurcher300b
Mon Jan 20, 2020 6:24 pm
Forum: DIY
Topic: Another DIY SS Amplifier with NVA Boards
Replies: 294
Views: 30517
Great Britain

Re: Another DIY SS Amplifier with NVA Boards

Maybe the darlington pair output stage with its high gain, sidesteps the whole issue? Don't confuse current gain with voltage gain. Not in valve land now. drivers (TIP31 & 32) can take 50 V That may be confusing. if they are C, then they will take 100v, but that's from +ve to -ve, (collector on one...
by Lurcher300b
Mon Jan 20, 2020 5:49 pm
Forum: NVA Discussions
Topic: New!!!!! NVA CD players
Replies: 255
Views: 50798
Great Britain

Re: New!!!!! NVA CD players

This is a good paper on op amp decoupling, and it also shows why replacing op amps in a circuit can come with side effects. https://www.analog.com/media/en/technical-documentation/application-notes/AN-202.pdf Thius has some good words on cap choice. https://www.analog.com/media/en/training-seminars/...
by Lurcher300b
Mon Jan 20, 2020 5:32 pm
Forum: DIY
Topic: Another DIY SS Amplifier with NVA Boards
Replies: 294
Views: 30517
Great Britain

Re: Another DIY SS Amplifier with NVA Boards

38V on the front end, 51V on the power stage. Of course I don't know the circuit, but what is the point of having lower voltage on the driver than the output stage? Normally the output stage is limited by the headroom of the driver stage. I would have thought that pair of voltages would only give t...
by Lurcher300b
Mon Jan 20, 2020 4:58 pm
Forum: DIY
Topic: Another DIY SS Amplifier with NVA Boards
Replies: 294
Views: 30517
Great Britain

Re: Another DIY SS Amplifier with NVA Boards

38V on the front end, 51V on the power stage. Of course I don't know the circuit, but what is the point of having lower voltage on the driver than the output stage? Normally the output stage is limited by the headroom of the driver stage. I would have thought that pair of voltages would only give t...
by Lurcher300b
Mon Jan 20, 2020 2:52 pm
Forum: NVA Discussions
Topic: New!!!!! NVA CD players
Replies: 255
Views: 50798
Great Britain

Re: New!!!!! NVA CD players

:grin: You are of course correct Nick and your views are always welcome. I was relying on others who had done the same with the same cdp and regulator (which they knew inside out) and who had sillyscopes. This opamp based feedback regulator was well known to cause issues for the unwary especially i...
by Lurcher300b
Mon Jan 20, 2020 11:42 am
Forum: NVA Discussions
Topic: New!!!!! NVA CD players
Replies: 255
Views: 50798
Great Britain

Re: New!!!!! NVA CD players

True. My thoughts and those of others on pfm (who were far more electronics aware than me) were that the inductive nature of the output of the regulator needed a bit of resistance (provided by the extra wiring) to prevent oscillation with the low esr caps that are decoupling at the input of the opa...
by Lurcher300b
Mon Jan 20, 2020 9:38 am
Forum: NVA Discussions
Topic: New!!!!! NVA CD players
Replies: 255
Views: 50798
Great Britain

Re: New!!!!! NVA CD players

It was interesting in the sense that i learned a few things
Without want8ing to be awkward, I don't know exactly what you could have learnt from that without a scope to see just what was actually happening.
by Lurcher300b
Sun Jan 12, 2020 5:26 pm
Forum: DIY
Topic: Another DIY SS Amplifier with NVA Boards
Replies: 294
Views: 30517
Great Britain

Re: Another DIY SS Amplifier with NVA Boards

karatestu wrote:
Sun Jan 12, 2020 12:10 pm
Hi Nick. We are talking about two psu's on the same channel (front end and output stage) not two separate channels.
Ok. Point taken.
by Lurcher300b
Sun Jan 12, 2020 11:15 am
Forum: DIY
Topic: Another DIY SS Amplifier with NVA Boards
Replies: 294
Views: 30517
Great Britain

Re: Another DIY SS Amplifier with NVA Boards

May be missing the point but as they are class II why connect the 0v from the two channels together at all?
by Lurcher300b
Wed Jan 01, 2020 3:00 pm
Forum: General Audio
Topic: Specifications - let's get them out of the way
Replies: 22
Views: 1404
Great Britain

Re: Specifications - let's get them out of the way

Most anything I buy should measure acceptably. That means it won't go unstable, go on fire, put a lot of DC through my speakers etc. I agree, unfortunately none of the measurements that are normally published for a amplifier will cover any of those cases. There are a number of things you do during ...