Clean Mains Connections = Good Sound

I recently bought a second-hand tuner, an Akai AT-550.  The condition of the mains plug pins was the worst I have ever seen.  Even though the connections pass relatively high voltages, they still need to be clean or sound quality will be affected.  I am particularly fussy about the earth pin connection.  Here is a picture of the tuner:

Akai AT-550 Tuner.

Akai AT-550 Tuner.

To clean the brass pins of corrosion and dirt, I use a fibreglass stick but sandpaper or even a knife can be used.  If you have the confidence, it’s worth taking a look inside the plug to make sure all three connections are good and that the fuse connections are not corroded or lose.  This shows the plug:

Showing the mains plug earth pin badly corroded.

Showing the mains plug earth pin badly corroded.

Showing the mains plug earth pin partially cleaned.

Showing the mains plug earth pin partially cleaned.

P1080295

Showing the mains plug earth pin fully cleaned.

I cleaned all three pins, not just the earth and when finished, they were all shiny.

If anyone needs an explanation of how to connect a mains plug properly, please do ask me and I will upload a post showing how to do it – not everyone knows.

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Every band member should read this . . .

. . . and anyone who loves music also, so they get to know what really goes on in the music business.

A good friend of mine has brought an article to my attention, written by Steve Albini; an American singer-songwriter, audio-engineer, band member of Shellac and much more.
It outlines (some of) the massive problems faced by up-and-coming bands trying to break into the music industry, at any level above playing pubs and clubs.

I recommend it:

‘The Problem With Music’ by Steve Albini

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Basic Media Amp and Speakers Idea

I finished working out the Box Construction Jig and found I had some 12mm MDF wood left over on the sheet.  I have some nice parts left over from the design of the Boombox and coming system so I thought I’d use the spare MDF to build a simple, compact HiFi system for our kitchen.  Nothing fancy, just an On/Off switch, a selection switch for only two inputs – Bluetooth and USB and that’s all.  The design is now complete and I’m about to add it to the cutting information for the MDF sheets.

But I think this would be a good production model and many others should find it a useful little amp.

So there are now two additional amp models, here are their salient points:

  1. a 14Wrms/channel and a 60Wrms/channel amp,
  2. only Bluetooth and internal DAC (USB fed),
  3. no tone controls,
  4. front panel has only On/Off and input selection,
  5. my amplifier PCB and top quality parts,
  6. small full range loudspeakers (Peerless?) with optional stands that include subwoofers,
  7. as small a footprint as possible given the internal components.

The MDF layout is almost finished, I’ll post pictures as it’s constructed.

Posted in Amp Cabinet, Amplification, Design, High Definition Sound, Loudspeakers, Media, Power Amplifier | Tagged , , , , , | Leave a comment

Box Construction Jig Design

My next job is to build the boombox cabinet (or box).  It will be made from 6 and 12mm MDF and I need to make sure that when glued together, all the sides are exactly perpendicular and not leaning over at all.  Over distance, a very small angle can make a big difference.

I am designing a jig to make this gluing job easier and more accurate.  It will also be of 12mm MDF.  The ‘Ls’ will be 10cm deep so won’t flex longitudinally at all.  The four ‘Ls’ will slide into each other like two combs coming together.  That can only happen in one direction so the upper two ‘Ls’ are broken and need bolting or gluing together once in place – you can see three holes in the corner, on the drawing below.

Box construction jig bracing.

Box construction jig bracing.

The above bracing will then be faced with 12mm MDF (as shown below).  This surface will allow me to push the panels that need gluing, up against the facing knowing it is absolutely perpendicular.  The jig will be laser cut by Exeter Laser so will be reliable true.

Each facing panel will be glued to the bracing at a distance of 30mm away from the other two facings.  This will allow up to 25mm MDF sheets to be glued together without becoming glued to the jig.  Any excess spilling out of the joint, can then be removed after the glue has set.

Box construction jig facing.

Box construction jig facing.

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CS4397/8 – A DAC Good Enough to Include?

I am a big fan of people with a passion for what they do, being enthusiastic about it and doing their best to do it well.  One such person I have come across is Lukasz Fikus who runs a family business dedicated to high quality HiFi and their web site is http://www.lampizator.eu/ (new window).  On his site he talks about the sound and build quality of CD players he has come across or more specifically – their DACs.

On the page http://lampizator.eu/LAMPIZATOR/CD_player_ranking.html (new window) he talks about the DAC chip CS4397 and CS4398 from the IC manufacturer Cirrus Logic (a quick explanation of what a DAC is and why you might need one is given at the bottom of this post).

I wasn’t going to include a DAC into my boombox as the digital audio world has been changing so rapidly recently that I thought it best to concentrate on the amplification system and let people chose the input they want/can afford.  There was also the extra cost involved, both monetarily and time-wise, as I would have to buy and listen to a few to find one suitable.

But having been reading Fikus’ ramblings for a while now I have come to respect his authenticity and lack of sales bias and now feel that if he says this DAC is that good, I should be comfortable in including it into the boombox.  Most importantly, it is the right price!

CS4398-DAC-Board

CS4398 DAC Board

It will be a squeeze to get it in since most space has already been taken but I’m sure I can do it and this will give the boombox complete usability as it will be possible to connect it direct to a computer via USB as well as the current Bluetooth, Phono, 3.5mm jack, 6.5mm jack combination currently catered for.  It is important for me to include a DAC if possible as I see the prevalence of computers being the future source of music listening (I’m not alone in this, it doesn’t take a genius to have worked that little gem out).  I know vinyl is resurgent and many argue that the sound quality is better than digital and in some ways I agree and in some ways I very much disagree – but that’s a different argument and the fact remains; if done right, a digital signal source is at least as good as an analogue one and in many ways (not least the convenience but also sound quality) is much better.  Digital amplification is a different argument and not one I will tackle here.

Actually, having thought a little about what to say when it comes to what DACs are and why they are needed, I think it best to make that a separate post as it will need a little thought and effort on my part to explain.  So maybe the next post?  Sorry to disappoint but I’ll have to make images and make sure the language is correct and not too technical.

Posted in DACs & File Formats | Tagged , , | Leave a comment

Chinese eBay HiFi Scam

Whilst looking for a used CD player on eBay, I found an amazing deal; a stunning and expensive CD player for a ridiculous ‘Buy It Now price’ – a deal too good to be true?  I was immediately sceptical so did the usual scroll down to look at the seller’s feedback and information.  Below that info, eBay shows ‘Similar Listings’ and that’s where I came across a notice from another member highlighting a scam being set by Chinese members.  I copied the listing in order to propagate the information.  I can no longer find the original member who highlighted the scam but many thanks to him for his input!

Chinese HiFi scam on eBay.

Chinese HiFi scam on eBay.

This is a copy & paste of what his listing said:

“Excuse the dramatic headlines but it had to catch peoples attention. This is a warning to all on Ebay UK because people are still buying these things. There are hundreds of under priced items being listed by scammers from China. I have pages of them in my watchlist some of which people have been bought and paid for overnight. An example is a Sonos Play 3 for £23.46 or a pair of Quad Electrostatic speakers for £45.26 with free postage. Most of the scammers (though it could just be one opening hudreds of fake accounts) have a name that consists of random numbers and letters. Some with a – or an underscore _ at the end of their name followed by a number. Also the title of most of their ads have ebayt or Ebayq or a random letter at the end of the item title plus none of them have a feedback score. Don’t buy off these scum thinking it’s a legit ad. I’ve reported over 400 of them but ebay have only removed some of them and they’re still coming. In the time it’s taken me to edit this and re-list this there’s 19 more crooked ads popped up so be careful what you’re buying folks. ”

An good example is shown in these two screen grabs of a listing:

Chinese HiFi scam on eBay example A.

Chinese HiFi scam on eBay example A.

Chinese HiFi scam on eBay example B.

Chinese HiFi scam on eBay example B.

Have you bought some HiFi that turned out to be a scam?
Do you have any ideas on how eBay could stop this happening?
Feel free to make any comments that would help.

Here are messages from other members in response to my listing:

Chris C**********
“Hi Matt – I saw your ‘scam alert’ listing. Thanks for taking the time to put it on. Last year I was scammed for £3,300 for a pair of B&W Nautilus speakers – from China. A mighty tempting price. The guy insisted no paypal – bank transfer only. The guy actually did have the speakers – I asked him to write my name on a piece of paper and put the paper next to the speakers and take a photo. And he did, and it looked real, and probably was. But after transferring the money he said he had big customs fees to pay to export them – believe it or not – and I grew wary. Eventually gave up. His account was closed by ebay as it turned out it was hijacked. So … if you can add this story to your scam alert thing it would be useful to others. If it’s too good to be true, it very probably is.”

Gerry
“hi
i reported this to ebay a month ago on the phono
to no avail

they are list item far to cheap with free post ie speaker 1000 a pair for £33,76

an buyer are paying for them and will never receive items

so easy to see ebaya / ebayb / ebayk and so on

if they pay buy credit card because its under 100 pounds it lost to them

good thinking scam card but ebay do not care”

Cookies
“Hi matt,

Your add is appreciated. I have seen loads and loads of adverts from China, top end stuff marked really low. I mean a B&o system for £24 with free shipping. You have to think really!?

Like you said a lot of ppl are buying these and thinking what a bargain. More of an impulse automatic buy.

I don’t think you will ever beat them, as they will continue doing the same scam. Maybe Ebay needs to do something, verifying an account / a person before they let anyone just open a account.

Ebay is good in terms of money back guarantee but they really need to do something to stop the problem.

Best of luck, and if it’s too good, then it probably is.”

Jza
“I’ve reported lots of these.

Let’s hope eBay don’t take this listing down

Good work”

Posted in Chinese eBay Scam Alert | Tagged , , , | Leave a comment

Pioneer SX-5580 Broken Pot / Switch Shaft Repair / Fix

The Pioneer SX-5580 I am renovating was not looked after very well at some point, surprising considering how prestigious a piece of equipment it is and how much it would have cost.  One of the problems was some bent volume control shafts and switch shafts.  The 10KHz Treble switch in particular was very bent indeed.  The others were not too much of a problem as it was only a case of bending the two split parts of the aluminium shaft into alignment.  But the 10KHz switch was a whole different game, just looking at it made me feel a little ill as I knew how hard finding a solution was going to be.  The shaft was broken right at the edge of its casing (as you’d expect) so did not protrude at all.

This picture shows the board this switch came from, the switch is already out having been de-soldered – you can see the gap it’s left in the assembly hanging at the bottom (the white card is polystyrene foam from a pizza box and used to insulate and protect the board that’s hanging in the middle):

Pioneer SX-5580 during repair.

Pioneer SX-5580 during repair.

This problem (broken potentiometer / switch shaft) is quite common and is now solved so I am going to put everything down here in case others find it useful.

First of all, I looked at the web forums and the consensus was buy a new potentiometer / switch.  That was not a solution for me as this switch is dedicated to the SX-5580 and finding a different switch to replace it would cost too much (approx. £50).  Plus I am renovating this unit to sell in order to finance Liquiphonics and buyers (understandably) want as much originality as possible.  So onto the fix…

All materials (as far as I’m aware) work harden, thats how a strong piece of metal can be broken, just keep bending it at the same point; eventually it will give and break in two.  I’m no scientist and in some ways understanding what happens to metal crystals when they stretch through work hardening is irrelevant; the fact is, if you keep bending a piece of aluminium rod, it goes hard and will at some point snap instead of bending.  Aluminium does this fairly soon in the number of bends and since this shaft was bent so much, I felt very nervous about forcing it too much and too far.  I used a piece of steel tube with a good fit and put it over the end of the shaft and pulled, I did this in situ so the casing took the load and not the PCB.  It bent a little but not enough so I did it again and looked at the results.  I kept doing this until it was very nearly inline – and then it broke.  There’s no point in me telling you what I called it as you can probably make a pretty good guess.

When taking a switch apart, it’s good practice to put it in a position that will help you put it back together.  That way all the parts will be in correct alignment so say -10dB on the scale gives -10dB and  not +20dB.  I turned the switch so that it was completely clockwise and then took lots of photos of it to show me where the insides were positioned:

The Pioneer 5580 10KHz Treble switch.

The Pioneer 5580 10KHz Treble switch.

Inside the 10KHz Treble switch.

Inside the 10KHz Treble switch.

Inside the 10KHz Treble switch.

Inside the 10KHz Treble switch.

Inside the 10KHz Treble switch.

Inside the 10KHz Treble switch.

Inside the 10KHz Treble switch.

Inside the 10KHz Treble switch.

Inside the 10KHz Treble switch.

Inside the 10KHz Treble switch.

Inside the 10KHz Treble switch.

Inside the 10KHz Treble switch.

The 10KHz switch disassembled.

The 10KHz switch disassembled.

The 10KHz switch disassembled.

The 10KHz switch disassembled.

The shaft with two beryllium washers.

The shaft with two beryllium washers.

When metal (or any other material) breaks the slight imperfections in its structure cause greater or lesser stretching of the material and this is like a finger-print.  In other words, the two pieces will fit closely together in one position only.  This ‘fingerprint’ is useful as it helps to align the two elements.  Nothing is perfect and there may be subtle differences between the two parts but in my case they were close enough for this to not be a problem.  You can see the shape of the metal in this picture:

The broken ends of the shaft.

The broken ends of the shaft.

Putting the two together showed the join to be very tight fitting and the shaft to be almost straight.  I then superglued it in this position.

The shaft after supergluing.

The shaft after supergluing.

I haven’t measured the angle but looking at it against a right angle it looks some fraction of a degree.

A right-angle showing alignment of shaft after supergluing.

A right-angle showing alignment of shaft after supergluing.

Superglue is nowhere near strong enough for this application and even if it were stronger, I would feel uncomfortable about relying on it.  What I really wanted was the two parts to be mechanically joined and the best way I could think of was to use a split pin rod, the split rod can be seen in a picture further down.

To hold the two parts rigid together while I drilled it, I put three layers of heat-shrink sleeving around the shaft:

The shaft before drilling showing heatshrink tubing.

The shaft before drilling showing heatshrink tubing.

The picture below shows the drill in position.  Actually I took the photo after all the work was done but took it just to be complete – I know how scary this sort of thing can be even for experienced workers in this field so every picture counts.  Plus I’m a bit anal when it comes to this sort of thing.  Down with this sort of thing (that’s an in-joke for lovers of ‘Father Ted’):

Drilling the shaft.

Drilling the shaft.

When holding a hand-drill it must be kept perpendicular to the work, the last thing you want is for the bit to exit out the side of the shaft.  That’s unlikely as it’s not that hard to keep the drill vertical but even a little miss-alignment may mean the shaft has a kink in it at the joint which would totally defeat the whole point of doing this.  Fortunately with this shaft, it has a split down the middle (as many do) and that meant the drill bit was kept in correct alignment in the z axis (away and towards you).  That means only the x axis has to be judged by the person drilling.  So keep the slot running left to right (along the x axis) and it is then easier to see that the drill bit is vertical.

Drilling the hole broke the superglue hold but I had put enough of a hole in the lower section for that to not be a problem.  I simply pulled out the upper section and carried on drilling:

The shaft during drilling showing heatshrink tubing.

The shaft during drilling showing heatshrink tubing.

Once drilled I removed the heat-shrink sleeving.  The hardened steel split pin can be seen to the left of the shaft:

Shaft showing holes and spring pin.

Shaft showing holes and spring pin.

Here is something important to note.  The split pin I used was 2mm in width and 12mm long (the drill bit I used was 2mm though measured 1.96mm with a vernier gauge).  I wanted about 7mm in the lower section of the shaft leaving about 5mm in the upper section.  Since I have a shite memory I totally forgot to watch how far I drilled in, most of my brain cells were watching for alignment (the rest were off napping somewhere).  I could have put a piece of PVC tape around the drill bit to show me when to stop.  The result was I drilled about 2mm too deep into the lower section.  I cut a piece of 14 SWG (2.032mm) tinned copper wire and dropped that into the hole.  In case you don’t know (but you probably will), wire cutters leave a right-angle cut or a sloped cut depending on which end of the cut you look at – I used the cutters to give right-angles at both ends.  This piece of wire stopped the split pin from going in too far when I tapped it into the lower section with a small hammer.

One thing I did note from looking at the forums (a list of which is below), they recommend JB Weld so I bought some and used that to glue the too parts in addition to the pin.  Before glueing, since I would not be able to see the join of the two parts, I put an indelible mark on both sections of the shaft to make it easier to align once the JB Weld was added.  The marks are only for rough alignment as your fingers will feel it drop into place when exactly aligned:

Shaft pinned and glued showing alignment marks.

Shaft pinned and glued showing alignment marks.

Having put the glue on and pushed the upper shaft section onto the split pin using the small hammer and watching the alignment marks, I smeared the glue out and over the join to help reinforce the junction and fill the gap.  I then left the whole thing for the glue to set over night and cut off the excess with a sharp knife (scalpel) leaving a smooth finish.  To clean the shaft I used a fibreglass cleaning stick.  I’m mentioning this here as I find this stick to be incomparably good at cleaning things such as this and especially corroded switch or connector contacts.  This stick is a rod of long glass fibres held together with plastic (presumably heat-shrunk on).  The ends of the fibres do the cleaning and being made of glass they are hard and abrasive but very fine indeed plus the stiffness (and therefore abrasion) can be regulated by the length of the fibres showing by cutting back the plastic – so one end can be long, the other short.  I have had one for decades now, use it all the time and having started out at average pencil length, it is still three inches long.  So well worth any cost involved.

Here is the finished shaft join:

Pioneer SX-5580 Treble 10KHz Shaft finished.

Pioneer SX-5580 Treble 10KHz Shaft finished.

One last thing and my apologies if you already know this but if not it could prove useful.  Drill bits should not be put too far into the drill’s chuck.  Drill bits are hardened at the cutting end but softer at the chuck end.  This is so the bit does not bend (or break) when pushing forces are applied.  If you find your bits are breaking or bending you are putting it in too far.  I generally put them in no further than 1/2″ (1.5cm).

Forums I used, many thanks to those people:

http://www.harmonycentral.com/forum/forum/guitar/acapella-41/1190182-
http://audiokarma.org/forums/index.php?threads/repairing-broken-pot-shaft.377979/
https://www.talkbass.com/threads/how-to-repair-a-partially-broken-pot-shaft.562200/
http://www.mylespaul.com/forums/showthread.php?t=161235
http://www.tdpri.com/threads/broken-pot-shaft-got-any-ideas.79289/
http://homerecording.com/bbs/special-forums/diy-mods-and-homebrew/repairing-broken-pot-amp-266725/
https://www.thegearpage.net/board/index.php?threads/pulled-the-shaft-out.1009977/

http://music-electronics-forum.com/t30639/

Posted in Construction, Finance, pioneer, Receivers, renovation, sx-5580, Vintage HiFi Renovation | Tagged , , , , , , , , , , , , , , , , , , , | Leave a comment