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Doing interesting things with electronic keyboards

Posted 30th July 2014 at 02:44 AM by fas42
Updated 31st July 2014 at 12:24 AM by fas42

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...
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Posted in Tweaking
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Old

A Better Audio Comparison Tool

Posted 2nd June 2014 at 08:25 AM by fas42
Updated 14th July 2014 at 03:01 AM by fas42

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...
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Old

How good can the sound get?

Posted 12th April 2014 at 03:40 AM by fas42

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...
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Old

2,000W into 1 ohm

Posted 12th February 2014 at 05:10 AM by fas42
Updated 13th December 2014 at 12:52 AM by fas42

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.

.
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Old

Fix it time for PC monitor speakers

Posted 16th December 2013 at 06:23 AM by fas42
Updated 22nd June 2014 at 07:35 AM by fas42

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 ...
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To boldly go where no audiophile, or, perhaps just me, has gone before ...

Posted 23rd December 2012 at 04:07 AM by fas42
Updated 23rd December 2012 at 04:11 AM by fas42

As 'threatened' in a comment in abraxalito's blog I'm going to kick off posting and linking to some samples of sound generated by myself, at the moment examples of replay on my system, recorded using a very basic technique.

I'll probably regret it, but I'm going to put up a rough and ready trial run, to give a smell of what I'm aiming at. It's full of problems, but it gives some good indicators of what I'm dealing with, and hopefully some feedback will help me for future runs.

The system is my 'dud' HT all-in-one setup, heavily tweaked, and the recording device is a Fujifilm S4000 camera, which does HD video rather nicely, with mono 44.1/16 audio thrown in - that's handy. To maximise sound quality and minimise card storage used, hopefully, the lens was covered while recording, yes, no pics! Unfortunately, signal to noise is poor and the automatic volume control keeps falling over its feet, but you can't get everything for that sort of money ...

...
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Old

Sydney HiFi show - a mostly eye opening, not ear opening, exercise ...

Posted 22nd October 2012 at 10:58 PM by fas42
Updated 24th October 2012 at 12:33 AM by fas42

Well, as mentioned elsewhere checked out the first proper show we've had in decades, and in hindsight it has been a very worthwhile, educational experience. Not because I heard magic audio I've never heard before, but, because I then browsed a collection of other people's thoughts and takes on the various sounds heard at the event, on another, Australian, audio forum.

Which showed me that people are in very different spaces, as regards to what is considered, "proper sound". Obvious of course, but it still throws one, makes one question one's ideas and thinking on matters ... for a split second, at least ...

My personal take on the show is that there has been a very discernable improvement in the standard, or average, quality of sound of a normally assembled system which has had only a minimal amount of tweaking applied to optimise it. Problems that were obvious in previous such efforts were far less apparent, you didn't want to run screaming from...
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Old

Audio heaven? No, not me, the other guy ...

Posted 12th July 2012 at 02:39 AM by fas42
Updated 16th July 2012 at 01:16 AM by fas42

This follows a suggestion from another member -- thanks, bear! -- to chronicle at least one journey in optimising sound. And, yes, it's not one of my efforts, because the way I do things is very messy: they look incredibly messy, full of false turnings and bits of "I wonder if this is actually doing anything positive now". Enough to get anyone watching closely thoroughly confused ...!!

The story is that a small music listening group kicked off, then faded away. But from that an ongoing exercise began, where a younger, very enthusiastic DIYer was happy to hear my feedback on what path to take with his system, and this has continued for a couple of years, with quite substantial, positive gains in sound quality, to this day.

So, to give a clearer picture of the angle I'm coming from I'll attempt, from memory, to list the steps taken, in fairly general terms, and what the various ups and downs in the process were ...

At the start, when I first...
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Old

Musical monitor: Okay, what's this "musical" tag here mean, really??

Posted 8th July 2012 at 02:24 AM by fas42
Updated 16th July 2012 at 01:21 AM by fas42

I alluded to this in the first post on the thread, and it's worthwhile "defining" it a bit more.

Everybody would have a gut understanding as to what I mean, but what actually is it, and how do I measure it, to assess whether I've achieved it? There are the people who live and die by the conventional audio measurement yardsticks, and then there are the others who feel that these animals leave a lot to be desired. Again, look at the activity on the "Sound Quality Vs. Measurements" thread ...

Well, I'm pretty obviously in the latter camp, the standard numbers that an AP setup will pop up will mean very little, and since my project includes speakers the nightmare of getting meaningful distortion figures for the full path of the sound exists. So, I'll use the next best thing, my ears.

To make life easy here, I'll use a pretty accessible test object: the acoustic piano. We have one of those beasts in the listening area, my wife plays,...
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Musical monitor: Some comments on the positive input in the original thread

Posted 7th July 2012 at 05:45 AM by fas42
Updated 16th July 2012 at 01:21 AM by fas42

By tnargs:

Quote:
I was assuming we were going to take something like a Behringer 2031A (2 way, 8", active, affordable) and see what tweaks are on the table.
Most perceptive ...

Quote:
Whenever I see a measured FR of a Behringer it looks nice and smooth and flat, off axis too, so it seems a decent start.
Exactly so.

Quote:
Although Lynno's post is true enough, I thought we would be keeping the drivers and looking at any gains from astute use of felt or resin (on or around the cone/dome), replacement of dust cap, stiffening or dampening the pressed steel driver frame... what else?
Possibly will improve the frame in some such fashion; and look at stronger coupling of the whole driver assembly to the carcase such that vibration is transferred in the most direct path to the surface the monitor is sitting on.

But these things will be only addressed after the electronics are sorted out, and I see how well the driver behaves itself at maximum SPLs.
...
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