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Old 23rd October 2012, 05:36 PM   #1521
DF96 is offline DF96  England
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Quote:
Originally Posted by OnAudio
Later there was a science fiction piece that went un answered
The diagram in your post 1135 was certainly fiction, but not much to do with science, and it was not unanswered: I pointed out the flaws in the bottom of post 1138.

The misunderstandings in your post 785 might not have been answered, though.

Why drag them up now, when they are best forgotten?
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Old 23rd October 2012, 06:13 PM   #1522
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Originally Posted by DF96 View Post
The diagram in your post 1135 was certainly fiction, but not much to do with science, and it was not unanswered: I pointed out the flaws in the bottom of post 1138.

The misunderstandings in your post 785 might not have been answered, though.

Why drag them up now, when they are best forgotten?
Thank you DF96. A very simple circuit would be a passive first order low pass filter. What happens when you increase the load resistance ?
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Old 23rd October 2012, 09:27 PM   #1523
DF96 is offline DF96  England
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Quote:
Originally Posted by OnAudio
A very simple circuit would be a passive first order low pass filter. What happens when you increase the load resistance ?
Not certain about relevance, but it would depend on whether it was CR or LR.

For CR low pass increasing the load resistance increases attenuation and raises corner frequency.

For LR low pass increasing the load resistance does not affect attenuation and lowers corner frequency. So what?
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Old 23rd October 2012, 09:53 PM   #1524
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Originally Posted by DF96 View Post
Not certain about relevance
For LR low pass increasing the load resistance does not affect attenuation and lowers corner frequency. So what?
Thank you DF96. Does this in any way affect transient response ?
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Old 23rd October 2012, 10:13 PM   #1525
DF96 is offline DF96  England
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Just to clarify, by 'increasing the load resistance' I actually meant 'applying a greater load' i.e. reducing the numerical value of the load resistance. Sorry for the confusion.

My point is that CR and LR filters behave in opposite ways as the R value changes. I seem to recall confusion on this might have been the original issue.
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Old 26th October 2012, 02:27 AM   #1526
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What would be the instantaneous max VA for a 300VA transformer ?
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Old 26th October 2012, 04:06 AM   #1527
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Quote:
Originally Posted by AndrewT View Post
Did you mean to point to post1501? Twice?
In this case, it would be a lot more reliable to type the post number.
Here's the parameters:
Intra-thread links to attachments works fine,
Inter-thread links to attachments work fine,
intra-forum/inter-thread links (between two threads) links to posts work fine,
but intra-thread links (within same thread) to posts are hit or miss.
I also got 1501 twice.

For a large project, here's a workaround:
Discussion, simulation and testing on the big "main" thread, versus soldering and shopping on the little "build" thread.
A build thread is a "summary" concept and post 1 is re-edited in reaction to new questions in order to create more effective documentation. To avoid intra-thread links (that can miss the target), the links must refer to a different thread, which is the longer main/development thread. A build thread (a summary) can be started as a collection of notes and links all in post 1 of a new thread (post 1 has forever edit), and that can be reorganized into something cohesive after the task of reading through and making notes on a long thread is completed. The majority of build thread content is actually posted on the main thread, and, in that case, the links work.

----

Meanwhile, back on topic. Do amplifier topologies vary widely on power supply requirements, or is that one unusual? The low bass power is generous and audio resolution is seemly with just 160va and 4400uF per rail for my circlo monobloc. However, my other amplifiers seem to need more voltage, double the current and triple the capacitance before achieving a similar performance. Why?
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Old 26th October 2012, 05:54 AM   #1528
fas42 is offline fas42  Australia
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Quote:
Originally Posted by danielwritesbac View Post
Meanwhile, back on topic. Do amplifier topologies vary widely on power supply requirements, or is that one unusual? The low bass power is generous and audio resolution is seemly with just 160va and 4400uF per rail for my circlo monobloc. However, my other amplifiers seem to need more voltage, double the current and triple the capacitance before achieving a similar performance. Why?
A simple answer would be the the PSRR of the amplifier circuit, the ability to ignore the fluctuations of the voltage rails, especially at high frequencies. Real supplies with minimal specs inject a lot of rubbish into the amp, and there are dramatic differences in the way the different circuit configurations react. So, if you're not sure, build a Mack truck of a power supply ...

Frank
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Old 26th October 2012, 08:00 AM   #1529
AJT is offline AJT  Philippines
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Quote:
Originally Posted by OnAudio View Post
What would be the instantaneous max VA for a 300VA transformer ?
how hot can you allow your traffo to become?
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Old 26th October 2012, 10:04 AM   #1530
AndrewT is online now AndrewT  Scotland
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instantaneous could be 100ms or 10ms or 1ms or 100us or 10us or 1us or more accurately an instantaneous moment that has no measurable time period. It is an instant.
If the period is very short there is little time for any heating to occur.
Then there will be no measurable increase in temperature.

For very short term overloads, I'd suggest 10times VA is acceptable. Transformers are very tolerant of short term overload.
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