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fas42 fas42 is offline

diyAudio Member

About Me

  • About fas42
    Biography
    Probably worth mentioning I'm an EE, but life took me elsewhere after graduating ...
    Location
    NSW, Australia
    Interests
    Achieving totally convincing sound. As well as universal happiness, world peace, etc, etc ...
    Occupation
    Retired from the computing industry
    Country
    Australia
  • Signature
    Frank "All truths are easy to understand once they are discovered; the point is to discover them." - Galileo

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  • Last Activity: Today 01:49 AM
  • Join Date: 19th June 2012

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View fas42's BlogRecent Entries
Latest Blog Entry

Posted 30th July 2014 at 02:44 AM by fas42 Comments 10
Posted in Tweaking
Provoked into Yet Another Project, fiddling with the Yamaha PSR-6700 Portatone we bought over 20 years ago, for my wife to have fun with. This is a solid unit, quite heavy, well thought of even now, with 76 keys - was top of the range, and was the best sounding of the brands and models we looked at the time, in that type of thing. Sometimes called an arranger keyboard, because it can do fancy backing accompaniments, the one-man band thing ...

For those who are not into such, this is an all in one box, very sophisticated synthesizer with internal amp and speakers. Think of it like a reasonable hifi system, where the source material is computer generated, and can get as fancy and realistic as one wants, especially these days. Even in bygone decades remarkable music was created using such devices - Peter Gabriel's well thought of 4th album, Security, was based extremely heavily on sounds from the Fairlight CMI, an Australian made pioneer of this technology.

As...

Posted 2nd June 2014 at 08:25 AM by fas42 Comments 5
Posted in Tweaking
I've mentioned a few times the difficulty in using the software tool, DiffMaker - and others have experienced similar issues. So, I'm thinking seriously about attempting to put together a "better" utility, something that will be more intelligent in correlating between different versions of sampled waveforms, wherever they came from. And it will be specifically aimed at trying to ferret out the deep down differences, not the obvious stuff like frequency response, phase shifts and the like - but rather the low level, detail variations that seem to be so important in subjective quality evaluation.

To give an idea of the "challenge", consider taking 2 recordings from 2 vinyl plays of a particular record. Having already seen what results, this is impossible for the likes of DiffMaker to handle - the constant speed variation between the 2 captures completely defeats it. But this what I would aim to be able to deal with, to synchronise in meaningful ways between...

Posted 12th April 2014 at 03:40 AM by fas42 Comments 3
This will be a collection of ideas developed and experiences encountered in my personal foray into the world of audio. In part, this is to counter much of the negativity and beliefs out there about the limitations of bog-standard, vin ordinaire, reproduced sound from conventional recordings, heard via a normal pair of speakers.

First of all, the sound can get very, very, very good. Far beyond normal hifi, better than "live" much of the time ... so how can that be so? Because, typically for the recording session the positioning of the microphones, and acoustics, are optimised and tweaked by the sound engineers to pick up a "quality" well beyond what you as an ordinary audience member, concert goer, would experience.

So, how good? Well, for a start you can get "invisible" speakers, meaning that they can't be perceived as being the source of the sound; even if you go up to them and stare at them very closely, and move from side to side...

Posted 12th February 2014 at 05:10 AM by fas42 Comments 17
Posted in Tweaking
I mentioned in a thread a while ago about doing an exercise of engineering an amp capable of delivering 2k watts into a 1 ohm load, with distortion aiming at the magical ppm figure. This is still happening, and making progress ... key problem as I saw it was managing crossover distortion intelligently - I'm looking at a conventional class AB output stage at the moment - and it didn't make sense to try and control it using a classic global negative feedback approach.

By nature I'm an excellent scavenger, I look to see what ideas are already out there - so I'm trying out some concepts in using local negative feedback. This is evolving, step by step - and showing promise: in a simulation of the output stage only, getting effectively 2kW in 1R, at 200kHz with reasonable stability - and the waveform at this stressful frequency looks pretty good, there is still some crossover glitching, but I'm reducing the visible level of it steadily.

.

Posted 16th December 2013 at 06:23 AM by fas42 Comments 26
Posted in Uncategorized
Bummer!! After mentioning that Brad's (bcarso) units were doing very nicely I swapped CDs while they were set to max. volume, doing a good job on a classical piece. Unfortunately, the new disk was heavily compressed pop, my mind was elsewhere, and I hit the volume control a second too late - everything's OK except the right speaker has dropped about 6dB in volume, ...

I suspect that some protection circuitry has tripped, but it's not resetting. Which means, unless anyone has a good idea otherwise, that I'll have to dive inside and sort things out. But, on the other side of the equation that may be an excellent thing to do, it will give me a chance to do some more adventuresome tweaking ...

Trouble is, I'm lazy ...
Recent Comments
Looking nice ... how...
Posted 18th December 2014 at 11:12 PM by fas42 fas42 is offline
Learning quite a bit...
Posted 15th December 2014 at 10:00 PM by fas42 fas42 is offline
This sorta died, didn't...
Posted 12th December 2014 at 09:42 PM by fas42 fas42 is offline
I need a good laugh...
Posted 30th August 2014 at 06:31 AM by fas42 fas42 is offline
A separate box is good,...
Posted 30th August 2014 at 12:10 AM by fas42 fas42 is offline
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