Pioneer SX-5580 Receiver Refurb

Here is what I’m working on at the moment, a Pioneer SX-5580 monster receiver (amplifier with built in tuner).  As far as I’m aware, it is identical to the SX-1050 but is in black instead of all aluminium.

Pioneer SX-5580 Monster Receiver in black.

Pioneer SX-5580 Monster Receiver in black.

This photo shows what the front panel should look like if it wasn’t all dirty and a little scratched:

Pioneer SX-5580 Front Panel.

Pioneer SX-5580 Front Panel.

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High Resolution Audio, MQA and Others

Not sure where to start with this post. I suppose I should just ramble on…

CD audio was a little short of musical quality and has been bemoaned ever since its introduction pretty much. By anyone who likes quality above convenience at least. Vinyl has hung around and is now even making a comeback. That is due to the resolution of vinyl which is largely dictated by the size of the plastic molecules as much as the recording medium but may also be due to the artistic nature of the artwork with a pressing and the emotional quality of owning vinyl.

Now that computers are coming into their own, we have the opportunity to increase the resolution of digital audio. But then mp3 has become popular because of its small file size of around 1/10 of an AIFF or WAV (depending on the compression level) and apparently that small file size is bought at the expense of losing the higher frequencies. Everyone loses their ability to hear higher frequencies as we age and the older we are the less up the frequency range our ears can go. But then, there is another argument that although we cannot literally hear the higher frequencies, we can still hear the effects of higher harmonics so they are necessary.

I have a personal theory that the older we are, the better our brains are at filling in the blanks so we may not literally hear a high pitch sound, because the hairs in our ears are not there but our ears do hear the lower frequencies and our brains fill in the gaps (higher frequencies) because from experience, it knows what should be there. But that is a different discussion.

So mp3s have brought greater convenience at the expense of some musicality and that was fine since digits were still expensive when that format was designed, especially for download/streaming. But things have moved on again in computer land and efforts are now being made to increase the resolution to exceed CD quality both in terms of sampling frequency increases (44.1KHz for CD and 96KHz+ for HR) and bit depth (how many bits are used in each sample – e.g. 16 for CD, 24 for HR).

I am not convinced that increasing the bit depth to 24 makes that much difference since many recordings do not reach 16 bits in dynamic range anyway, so increasing to 24 would make no difference. On the other hand, regarding sampling rate, 44.1KHz seems utterly inadequate to me – how can you sample a frequency of 22KHz (within the frequency range of young people) with just 2 samples and expect to recreate the exact wave shape?

None of this affects my boombox or amplifier designs since I decided to leave that side to others – it has taken me nearly seven years to get this far with my design, how could I keep up with developments in digits! My boombox (ghettoblaster) and amp will both be Bluetooth connected but that unit is bought in and so replaceable as digits develop further and there are six inputs in all (including four phono/RCA) with only one for Bluetooth. The other input is two jacks in parallel (one 3.5mm and one 6.5mm) so musicians can play music from their e.g. iPod and play along with it with say a guitar or piano etc.

But here’s the main purpose of this article, to draw your attention to how some companies are taking advantage of us by doing bad things with digits and saying they are doing good things. One example would be how some companies are taking old recordings and converting them to High Res by resampling them at 24bit/96KHz. For me, these files are not high resolution if the original was not high resolution. For example, recordings made in the 60’s may have all sorts of distortions and noise caused by the lack of quality recording equipment. The HR version may simply be a high res recording of a crap original – it will still sound crap, only that crap will be accurately reproduced. In other words; beware the claims of High Res companies.

One person who really does seem to know what he is talking about (he’s an experienced recording engineer with his own studios and also a musician) and is fighting this cause (the reason I follow his blog postings) is Dr. Aix (Mark Waldrep). You can follow his posts here:

http://www.realhd-audio.com/

He is also publishing his own book about Hi Res which can be found here:

http://aixrecords.com/

Mark’s latest post gives a link to an article by Jim Collinson of Linn and I urge anyone interested in HR to give it a read.  The article claims a company called MQA is developing technology that will very much stifle new music and lock us all into their monopoly.  Here is a link to that article:

https://www.linn.co.uk/blog/mqa-is-bad-for-music

Happy listening (and reading),

Matt

Posted in DACs & File Formats, Ghetto Blaster / Portable Music Player, High Definition Sound, Media, Music, Signal Source, Vinyl | Tagged , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , | Leave a comment

DXF v SVG files – What he said!

I had problems with exporting files so the laser cutter company can understand them and they are accurate.  The reason behind it is me using the free, open source software Inkpad (and my lack of knowledge in this area).  It’s a good vector drawing app but there are limitations when exporting especially to .dxf files (Drawing Interchange/Exchange Format).  Here is the post a question of mine prompted from exeter-laser.co.uk, definitely worth a read if you need to export SVG (scaleable vector format) to DXF:

http://exeter-laser.co.uk/blog/2017/02/09/file-formats-again-dxf-vs-svg-today/

If you need to export .dxf files from an Apple Mac, here is a link to free to download (with restrictions) DXF software from a nice German company:  http://www.schaeffer-ag.de/

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Connections Conundrum

I spoke in my last post about needing to find connectors to link the wires between the amp PCB and the outputs.  I just spent the whole day looking at the web sites of RS Components, Farnell, Maplin and eBay.  Although there are literally tens of thousands of different types, I am unable to find anything that fits all my needs: silver plated contacts, not expensive, not large, 5A+ rating.  Most connectors are either gold plate or zinc/tin plated.  They are also expensive, the cheapest costing around £16 for a full set.  I have even considered cutting up a multipole connector but it is still not right.

I hadn’t expected this being a problem, I’ll have to go and have a good ‘thinking sideways’ session to see where to go from here.

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Dimension Number Crunching

Numbers for rear PCB access panel.

Numbers for rear PCB access panel.

The number crunching to work out the dimensions of the MDF woodwork is coming to an end!  Thank goodness for that, it’s been mind bogglingly difficult and a long job.  You’d think it would be straightforward to work out but no.  I’m using the free, open-source software Inkpad.  It’s great, especially considering it is free.  But I can find no way of altering the origin of the measurements so x=0 and y=0 start at the bottom left-hand corner of the drawing, not of the object to be measured.  Also complicating things is that Inkpad measures to the edge of an object, not its centre.  I have to measure the distances of centres from the edges of the piece and transfer them to another drawing which shows the cutting details for getting the MDF laser cut.

Front panel cutting dimension information.

MDF Laser cutting information: Front panel cutting dimensions.

So to find the centre distance of a hole from the edge of a piece of MDF I have to perform this simple calculation:

Centre point = (number for left edge of object) – (number for left edge of MDF) + (1/2 width of object) => (number for left edge of object) + (number for left edge of board on cutting drawing) – (1/2 width of object)

Bear in mind that the x, y, width and height numbers are all next to each other and x and y are especially easy to get mixed up after doing a dozen or so numbers.  It’s also easy for me to add half the width instead of subtracting half the width.

I have some decisions to make before finishing this part of the job.  The printed circuit board is attached to its access panel so it can be easily removed for service etc.  But that means adding connectors to connect the board to the outputs and inputs otherwise servicing and testing would be problematic.  I want to make this easy to work on by someone other than me, not make their lives difficult.  Everything goes wrong at some point, I need to plan for that so for example, changing blown output transistors is possible.  Once I have decided on which connections to use, I will know the size hole they will need and how far apart they can be and then use that information to add to the drawings.

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B&O Beogram 1200 Turntable Renovation / Service

B&O  Beogram 1200

B&O Beogram 1200

In order to raise some funds for this project, I’ve been buying various vintage bits and pieces; amps, turntables, speakers, receivers and fixing them up for sale.  This blog shows some pictures of the inside of a Bang & Olufsen Beogram 1200 with SP14 cartridge.

I took the thing apart and cleaned all its contacts, replaced the tonearm wire with silk covered, pure silver conductors.  All pulleys, rubber rollers,  belts and rubber bands have been thoroughly cleaned and the main bearing oil for the platter has been cleaned out and replaced with Van den Hul “Special Turntable Spindle Oil” which is “doped with microscopic Zirconium ceramic balls”.  Over the years, the pulleys, belts, bands and rollers get little lumps of black dirt stuck to them.  I don’t know what its constituents are but I should image it contains fluff, dead skin cells, grease and moisture.  The effect of it being there is to add a tiny little bit of wobble to the smooth running of the platter.  Maybe it cannot be heard, maybe it can but bear in mind that the variations in groove size and shape, that makes up the sound you get from an LP, are absolutely tiny.  I’m not going to quote figures as I’m sure you can imagine just how blooming small they are so any help in getting a fixed reference for movement of the platter and arm will be a good thing.

Changing the oil made a massive difference to the friction of the bearing.  The bearing oil in a vintage TT like this will be thick, even sticky, dried out, moisture laden, dirt laden and some will have evaporated.  With the old oil, turning the table off when at consistent speed, it would spin for about 3 revolutions and then stop.  With the Van den Hul oil, I got bored timing it still spinning after what seemed like 20 minutes, it just went on and on.

To my ears the change over to the silk covered, solid silver tonearm wires made a distinct difference also.  I won’t go into trying to describe the sound change because hearing that from others leaves me dry but I will say I much preferred the new silver wire, by far.

There was no plastic cover with this turntable, it probably got thrown away when the previous owner couldn’t stand the site of it being all scratched and cracked.  Plastic gets very brittle as it ages, I think it’s something to do with UV light decomposing it.  Plastic from this ear was also very scratch prone as opposed to the polycarbonate used now (a well know version of PC is used as bulletproof glass).  There are companies around that can make a new cover for you and they are surprisingly inexpensive – I always thought it would be prohibitively costly, apparently not.

But the main point of this blog is to upload all the photos I took (so I knew how to put it back together again) in case others find them useful.

Silk covered, solid silver, tonearm wiring.

Silk covered, solid silver, tonearm wiring.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O tonearm wiring connections to the SP14 cartridge.

B&O tonearm wiring connections to the SP14 cartridge.

B&O Beogram 1200 switch mechanism.

B&O Beogram 1200 switch mechanism.

In the pictures below, you can see some of the grime I’ve been talking about, black deposits on the pulley wheel:

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

Removing the circlip spring washer using round nose pliers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

Sulphur corrosion to the silver plate on the Moving Coil pre amp PCB:

B&O Beogram 1200 silver plated connections for moving coil preamplifier board.

B&O Beogram 1200 silver plated connections for moving coil preamplifier board.

B&O Beogram 1200 insides.

B&O Beogram 1200 insides.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 insides.

B&O Beogram 1200 insides.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

Silk covered, solid silver, tonearm wiring.

Silk covered, solid silver, tonearm wiring.

To replace the original tonearm wire, I soldered the new silver wire to it and pulled it through, pulling the new wire along with it:

B&O Beogram 1200 turntable wiring being replaced.

B&O Beogram 1200 turntable wiring being replaced.

B&O Beogram 1200 turntable wiring being replaced.

B&O Beogram 1200 turntable wiring being replaced.

The entire inside sub assembly:

B&O Beogram 1200 insides.

B&O Beogram 1200 insides.

Connections to the tonearm cartridge socket showing which ones go where:

B&O Beogram 1200 turntable SP 14 cartridge connections.

B&O Beogram 1200 turntable SP 14 cartridge connections.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

The two pictures below show the switch that controls the auto return mechanism, the large cob wheel with the groove in it is part of that mechanism.  What is missing from the shot is a small half-circle spring device that flips the switch contacts.  At the time it had fallen off and I only found out when the auto return did not work.  This spring clip comes off easily!  Not a great design.  I will put another image at the end of these showing where the clip should go – it won’t be of the clip itself as the turntable has now been reassembled and I’m not opening it up just to take another photo so will draw it instead:

B&O Beogram 1200 switch mechanism.

B&O Beogram 1200 switch mechanism.

B&O Beogram 1200 switch mechanism.

B&O Beogram 1200 switch mechanism.

The Beogram 1200 motor assembly:

B&O Beogram 1200 insides.

B&O Beogram 1200 insides.

Drive belt pulley and drive wheel:

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

A cog wheel on the main bearing to drive the auto return mechanism:

B&O Beogram 1200 turntable bearing gear.

B&O Beogram 1200 turntable bearing gear.

B&O Beogram 1200 turntable.

B&O Beogram 1200 turntable.

B&O Beogram 1200 turntable main platter bearing.

B&O Beogram 1200 turntable main platter bearing.

B&O Beogram 1200 turntable platter switching mechanism.

B&O Beogram 1200 turntable platter switching mechanism.

The spring clip that falls off easily is under this brown insulating sheet which is held on by a single nut:

B&O Beogram 1200 turntable platter switching mechanism.

B&O Beogram 1200 turntable platter switching mechanism.

B&O Beogram 1200 turntable platter switching mechanism.

B&O Beogram 1200 turntable platter switching mechanism.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable platter.

B&O Beogram 1200 turntable platter.

B&O Beogram 1200 turntable platter drive pulleys.

B&O Beogram 1200 turntable platter drive pulleys.

B&O Beogram 1200 turntable platter, spring-loaded centre.

B&O Beogram 1200 turntable platter, spring-loaded centre.

B&O Beogram 1200 insides.

B&O Beogram 1200 insides.

A picture of where the auto return mechanism switch has the spring clip that falls off if you look at it too firmly:

Distant view of automatic return switch spring clip.

Distant view of automatic return switch spring clip.

View of automatic return switch spring clip mechanism.

Close up view of automatic return switch spring clip mechanism.

 

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Construction Starts

Construction of the first Bluetooth Portable HiFi has started.  I am working on the power supply build.

The photos above show the banks of power supply capacitors, one for the positive rail and the other for the negative.  They are connected using copper foil to reduce impedance between the two sets.  My design uses up as much space inside the cabinet as possible, hence their physical format.  The Charge On/Off switch shaft runs between the two banks.  It doesn’t look pretty but it’s a good solution electrically.  IMBO.

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