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Old 10th July 2012, 12:55 AM   #4771
cab is offline cab
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Seems we have a difference of opinion. We have a yes and a no, but no reasoning to support either opinion. Hopefully Bruno will address the issue directly at some point....I am assuming that at some point Hypex put the ncore in bridged mode and tested them, both on the bench and with their ears.....
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Old 10th July 2012, 01:06 AM   #4772
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Quote:
Originally Posted by jtwrace View Post
I'm pretty sure Bruno said that it wouldn't change the amplifier sonically.
Perhaps. Can we merely assume that noise on the +/– output rails of a single Ncore is mirror-equivalent or more closely matched than noise exiting two Ncore modules operating in bridge? That's the salient question, imo.
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Old 10th July 2012, 01:14 AM   #4773
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And another question for Bruno, is the PIC16 chip the comparator? I want to add further power supply regulation to this critical component if possible (ie, if it's performed by an easily-to-me accessible chip).
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Old 10th July 2012, 04:00 AM   #4774
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Here's my thinking about the comparator. I'll give this despite my cursory understanding of comparator electronics; the thinking seems valid all the same. The comparator is the device (or chip or circuit stage) that renders the analogue signal digital. Post the comparator, that signal is a PWM codification of the original analogue signal. That codifying process is therefore, like any digital audio process, subject to jitter.

Being so, I want to provide ultra-quiet DC power to the comparator.

Somewhat serendipitously, I ran across this today. This is Hervé Deletraz speaking about his early (presumably class D) investigations (interview here):

Quote:
At the time I designed my first digital amplifier, I had to build all the electronics for the analog to digital domain, since such kind of converters didn't exist off the shelf, especially with the level of performances I needed. For a long time – several years - I tried to develop the "perfect" digital amp, but the biggest problem was the residual noise due to the clock jitter, which I wouldn't want to correct using a global feedback – my original 1984 digital amp was already an open loop design – and the biggest problem was the frequency response, dramatically affected by the speaker impedance, due of the use of the output filter.

Anyway I am still thinking about a digital amp, just in order to know what I would be able to do in this new, promising century…
I know Hervé's perspective is rather opposite yours on many aspects of audio playback. I'm not bringing him in here to raise those differences (re feedback etc). I just happen to agree with him on the importance of jitter as it relates to the comparator's function in digitizing the signal.
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Old 10th July 2012, 07:41 AM   #4775
ChrisPa is offline ChrisPa  United Kingdom
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The pic is not the analogue 'comparator'
Read Bruno's papers to understand what is going on in the amps. I've found him to be very good at his explanations

It's an analogue amp. No processor is involved in the amplification. There is no 'conversion to digital'

It's self oscillating. Something which also happens on the analogue domain

It's worth understanding exactly how the circuit works and exactly how it has been implemented before thinking of 'improving' it. Everything is surface mount for a very good reason
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Old 10th July 2012, 10:02 AM   #4776
ChrisPa is offline ChrisPa  United Kingdom
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Quote:
Originally Posted by Bruno Putzeys View Post
Any more votes for this?
Yes

I know that in the true spirit of DIY I can and should source crimps and shells myself, but the availability of spare/alternative harnesses or harness components would make life a whole lot easier.

I will be looking for Y harnesses
A spare harness set would have meant that I would have chopped the harness to length in my first lash-up

Alternatively shells and crimps would make it easier for me to make my own custom harnesses - and/or to modify the existing psu harness
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Old 10th July 2012, 10:03 AM   #4777
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Indeed the PIC is not in the audio signal!

The amp is a full discrete design, no chips used in the signal line....

Please be very carefull with tweaking, the design is optimized for very low EMI and obvious very good audio performance. Adding or changing components will have high risk to influence the performance. For sure changing the output caps. Caps what will not be a drop in replacement or with longer leads as 0,5mm is a no-go....
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Old 10th July 2012, 04:43 PM   #4778
badman is offline badman  United States
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[QUOTE=Sam Lord;3071178]Everybody and his cousin mounts TO220s without heatsinks, in spite of the 85% or so reduction in rated dissipation. So the heatsink police won't come knocking at your door... this time.

[QUOTE]

Any harm in adding some heatsinks? I was thinking clip-on types with one half cut off, so that it presents a vertical profile to the board components (read: doesn't overhang anything). Are the heatsink tabs grounded? do they need to be isolated from one another? I hope the attached diagram makes it clear.
Attached Images
File Type: jpg UCD T0220 Heatsinks.JPG (21.0 KB, 383 views)
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Old 10th July 2012, 05:14 PM   #4779
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Quote:
Originally Posted by ChrisPa View Post
The pic is not the analogue 'comparator'
Read Bruno's papers to understand what is going on in the amps. I've found him to be very good at his explanations

It's an analogue amp. No processor is involved in the amplification. There is no 'conversion to digital'

It's self oscillating. Something which also happens on the analogue domain

It's worth understanding exactly how the circuit works and exactly how it has been implemented before thinking of 'improving' it. Everything is surface mount for a very good reason
I understand the basics of this amp. Yes, the amp is self-oscillating etc. The pulse-code that emerges from the comparator is a digital representation of the analogue signal. Surely you're not saying the PWM codification cannot be better characterized as digital? It is, imo, no different than a PCM "signal" which, in the sense I'm speaking here, is for its part carried as an analogue waveform that can be viewed as such on a scope.
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Old 10th July 2012, 05:19 PM   #4780
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Quote:
Originally Posted by Jan-Peter View Post
Indeed the PIC is not in the audio signal!

The amp is a full discrete design, no chips used in the signal line....

Please be very carefull with tweaking, the design is optimized for very low EMI and obvious very good audio performance. Adding or changing components will have high risk to influence the performance. For sure changing the output caps. Caps what will not be a drop in replacement or with longer leads as 0,5mm is a no-go....
Thank you, J-P. I understand concerns about EMI and risks about deleteriously impacting performance.
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