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mikmas
23-09-2019, 22:57
Nothing biblical here chaps ....

Clearing some space in the loft last week and came across a box of old crap I though I'd skipped ages ago ... turns out I'm a worse hoarder than I thought :rolleyes:
Most of it was stuff I'd moved indoors after a garage clear-out some years back and clearly didn't have the heart to consign to the great scrapyard in the sky.

Among the odds and sods was this fine specimen of spaghetti bodging I put together over 40 years ago. At it's core is a bunch of off-the-peg bits and bobs from ILP ... a Kent based company that is apparently still in operation and selling the same HY60 'potted' amp modules on eBay.

Now looking very much the worse for wear, I used this as power amp until it was replaced by a Quad 303 in the mid 90s; initially with the ILP companion preamp and latterly a Quad 33:


https://live.staticflickr.com/65535/48784721116_6223b3a236_b.jpg

mikmas
23-09-2019, 23:11
My initial thoughts were to do what I should have done back then and take it to the tip with the next consignment of electrical scrap.
Unfortunately I'm too soft for that and instead opted to give the poor wee thing one last fling.
I took it out to the garage, wired in a pair of speaks and an RPi ... and switched it on (fire extinguisher in arms reach..)

Surprisingly (considering it's battered condition) it actually sounded quite good and pretty much as I remembered it. Nice punchy bass and plenty of sweet details elsewhere ..... soooo.

Time for a rebuild to bring this little gem back to it's former glory :) :)

As I mentioned, the amp is basically a couple of 'potted' amp modules. These are powered by a toroidal (something of a novelty when I first built it) fed through a simply bridge to supply 25v balanced.

https://live.staticflickr.com/65535/48784361768_24753031a7_c.jpg

... and these are the specs claimed by ILP:

https://live.staticflickr.com/65535/48784530838_00a3bc36ea_o.jpg


...... to be continued ;)

Light Dependant Resistor
23-09-2019, 23:48
Nice project, one of these looks like worth implementing to replace the ageing capacitors and rectifiers
https://www.ebay.com.au/itm/Finished-Dual-Power-Rectifier-Filter-Power-Supply-Board-For-Audio-Amplifier/163673472309?hash=item261bb2fd35:g:X3MAAOSwGIBZugA q

Jimbo
24-09-2019, 05:38
Nice little project Mike. I like old Quad stuff having owned and used a fair bit for the last 30 years. I will check in to this post as you work your way through.:)

REXTON
24-09-2019, 06:44
I'm sitting in my comfy chair waiting for the updates. Good luck.

mikmas
24-09-2019, 16:29
Thanks for the encouragement and suggestions chaps :)

I spent some time with a pencil and fag packet and came up with necessary dimensions for a new and slightly more logical/spacious layout.
A shiny new box is now on order from our friends in the far east and should arrive in time for Xmas :lol:

Shiny box link (https://www.ebay.co.uk/itm/T-2205-Full-Aluminum-Headphone-Amplifier-Enclosure-Power-AMP-Chassis-DAC-Case/312711663959?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649)

Yesterday I began dismantling (and de-griming) the components from the decidedly shagged perspex housing - unsurprisingly one of the two caps looked like this:

https://live.staticflickr.com/65535/48788763402_bcc8d80a89_o.jpg

A clutch of Vishay replacements is on order from CPC and I have also booked a new set of diodes (just in case) ... although the board and connectors look OK despite the ancient crud from the dead cap.

Clive
24-09-2019, 19:07
I remember ILP. I had one but not the HY60. Probably one of the first chip amps.... sort of anyway.

mikmas
26-09-2019, 13:35
Old case now stripped of bits and heading for bin .... all components cleaned up, boxed and awaiting new casing ... (some will not return)

https://live.staticflickr.com/65535/48798207443_f8baa6c590_z.jpg


In the meantime I am playing with possible layouts (using Photoshop)
... this is today's preferred model:

https://live.staticflickr.com/65535/48798703327_0d76f43410_c.jpg

mikmas
28-09-2019, 00:03
New caps delivered ...

https://live.staticflickr.com/65535/48806000806_4e4d8688fb_z.jpg

... and fitted

https://live.staticflickr.com/65535/48805647973_25235db24d_z.jpg

Also removed the old diodes, reflowed the trafo connections and added a new extension to the ground post.

Hopefully more deliveries later :)

mikmas
29-09-2019, 23:11
Revised orientation and layout:

https://live.staticflickr.com/65535/48817514556_111bc76757_c.jpg

mikmas
29-09-2019, 23:14
... and some more goodies from Mr Postman:

https://live.staticflickr.com/65535/48817151553_5e08bec11e.jpg


Now the long wait for Chinapost and the vagaries of UK import processes ...... could be gone a while :lol:

REXTON
30-09-2019, 07:48
:popcorn:

mikmas
30-09-2019, 22:28
eBay tracking says the case arrived in UK on Sept 27 - expected delivery date Oct 15 :eek::eek::eek:

... as if

REXTON
01-10-2019, 07:27
eBay tracking says the case arrived in UK on Sept 27 - expected delivery date Oct 15 :eek::eek::eek:

... as if

Yeah that's nothing new, welcome to the wonderful world of the UK customs service.

mikmas
02-10-2019, 20:49
eBay tracking says the case arrived in UK on Sept 27 - expected delivery date Oct 15 :eek::eek::eek:

... as if

Looks like my scepticism was vindicated ... man with the red van rang the door bell this morning, two weeks ahead of given date :)

https://live.staticflickr.com/65535/48833924531_db4504ce2f_z.jpg

All bits present and correct - and enough little screws in the bag for four more boxes :lol:

Unfortunately, busy til Monday so will have to curb my enthusiasm for now .... unless not .......

mikmas
02-10-2019, 22:09
Found an old slide from circa 1980 showing the amp in situ ... being fed by a (cosmetically modified) Uher preamp:

https://live.staticflickr.com/65535/48834287151_434e3e7380_b.jpg


... the only Chinese import I had at that time being the little drumming panda - 'from little acorns' etc :lol:

mikmas
04-10-2019, 15:26
Decided to start with the most tedious bit first and marked out the holes for the amp modules ... hate this kind of job :(
Hopefully will find some time over the weekend to cut them out and drill the other holes required.

https://live.staticflickr.com/65535/48842440096_7a49eeafa7_c.jpg

mikmas
08-10-2019, 19:36
So found time yesterday to cut the amp holes and a new front panel as well as drill all the necessary:

https://live.staticflickr.com/65535/48866593757_98154988d5_c.jpg

followed by a 'dry run' assembly:

https://live.staticflickr.com/65535/48865877263_3af28a2445_b.jpg

... after that - some serious snagging :(

(TO BE CONTINUED...)

mikmas
10-10-2019, 19:56
Today was pretty much job done bar a couple of not very important decisions (pot or no pot, silver or black faceplate...etc...)
Tested out for an hour or so in the garage with various speakers and, other than sorting an initial earthing issue, all went swimmingly :) :)

The main problems I encountered during the re-casing exercise related to the rating of the toroid (220v or 240v?) and some concerns with the mounting bolt.

I had measured the clearance of the toroid in the old housing and ordered the new case accordingly (knowing that it might be on the tight side height-wise).
Hadn't reckoned on the case being just a wee bit smaller than advertised (to be fair they had put a size deviation disclaimer on the bay listing .... 'between 1 and 3 cm' :lol:)
When I fitted the toroid initially on the dry run it was immediately apparent that it was just a smidgin too high and was flexing the top lid when I screwed it down.

As the top and bottom of the case are simply screwed onto flanges in the side panels, I sorted this by adding strips of 2mm plastic at either side and top and bottom - creating an additional 4mm breathing space at the top thus:

https://live.staticflickr.com/65535/48877287857_abd547cc5d_z.jpg

The eagle-eyed amongst you will probably notice the electrical tape liberally applied to the toroid mounting washer - just a cure for a bit of possibly unnecessary paranoia caused by too much reading on t'interweb :lol:

mikmas
10-10-2019, 20:25
I mentioned already that I had some niggles about the exact spec of the toroid that I sourced from ILP (at the same time I bought the HY60 amp modules and rectifier board).
I have the original spec sheets for the HY60 amp module and these mention two appropriate toroids for the set up - one for 120/240v and one for 220v.
As I was living in Holland at the time I suspected that the one I had was probably the 220v version - however the model number on mine didn't match either of those on the spec sheet :scratch:

After some searching around various suppliers websites, I came across a UK based transformer manufacturer who apparently used to make toroids for ILP so I contacted him - got a quick reply but he couldn't help me out with that model number (although he did suggest an appropriate alternative..)

Further searching got me the email address (tucked away on eBay) of the current owner of ILP who still sells the amp modules (although his main business now appears to be stair-rod related ...)
https://www.ebay.co.uk/str/ILP-Direct-Ltd?_trksid=p2047675.l2563

He confirmed that the model number I had given indicated a 240v primary ... phew ...

Unfortunately while scrabbling around toroid specs and data sheets in search of info and knowledge I came across some scarier stuff ..... :eek::eek:

(TO BE CONTINUED ....)

REXTON
11-10-2019, 12:27
Oooo you rotten so and so I was really enjoying your w write up

mikmas
11-10-2019, 23:56
Oooo you rotten so and so I was really enjoying your w write up

:rofl:
oops …sorry Andrew - didn’t realise I’d created an Eastenders worthy cliffhanger :lol:

Anyhoo - to continue …

For those of you unfamiliar with toroidal transformers, what you have is a donut shaped thing with loads of wire wrapped around the tasty bit, some big washers, and a long bolt running through the hole to fasten it down to the casing. Really simple mount then?… only problem is that it is a potential minefield with actual explosive potential (kind of)

Basically this:

“Mounting: Toroidal transformers usually come with a long bolt, nut and a disk for mounting in the case (sometimes with extra rubber disks). Be aware of a metal case that the top of the bolt does not touch the top of your case. Since this bolt is already touching the bottom, if it touches the top too then via the rest of the case will effectively make a shorted turn around the transformer core itself, and damage will result.”

Source: https://electro-dan.co.uk/Electronics/wiringtrans.aspx

So my problem was that I had a situation where if anything inadvertently ended up being put on top of the amp it could flex the top enough to touch the bolt and cause the end of the f**king world (or summat worse …. a blow fuse for instance*)

As the amp was destined to end up in the shed, the chances of this happening could be rated at about 110% certainly, every time :eek:

*see this thread for one of many examples (https://www.diyaudio.com/forums/power-supplies/307081-toroidal-transformer-mounting-insulated.html)

So a genuine problem looking for a genuine solution.


hmmm, I thought, and more besides ….. for quite a while.

:hmm::hmm::hmm::hmm::hmm::zzz::zzz::zzz::zzz:

Barry
12-10-2019, 11:58
Two possible solutions:

[1] use a nylon bolt to secure the toroid, or

[2] glue a piece of insulating material on the lid over where the toroid sits.

I did the latter on a Cambridge P50 slimline amp (Cambridge Audio were one of the first manufacturers to use toroidal transformers.)

REXTON
12-10-2019, 12:20
Nylon bolt is the way to go imho.

mikmas
12-10-2019, 12:52
After sleeping on this for a night or two, I narrowed the solution down to one of the following options:

1. Suspend the laws of physics indefinitely
2. Bin the lot and move on.
3. Ignore the problem - it may never happen
4. Buy a bigger box and start again
5. Isolate the bolt from the chassis securely


Obviously option 5 was the most appealing and/or perfectly feasible choice ...

I did consider the two options suggested by Barry above but rejected both ... the nylon bolt because I hate them and sticking plastic to the top because of the vents, which I wanted to keep above the toroid, and the messiness.
The actual implemented solution was simple, secure and just as effective:

The bolt is an M5 so I drilled out the mounting hole to 7 mm and inserted a rubber grommet; on top of this a square of plastic with a hole to clear the grommet and a penny washer to restrain the bolt head thus:

https://live.staticflickr.com/65535/48884458613_d461f55cfb.jpg

After mounting the toroid I checked for continuity with chassis earth = zero, zilch, nada.
Nevertheless, I added a couple of layers of insulating tape to the toroid top plate 'just in case' ... :lol:

Job done - another good night's rest earned :thumbsup:

Light Dependant Resistor
12-10-2019, 13:12
:rofl:
oops …sorry Andrew - didn’t realise I’d created an Eastenders worthy cliffhanger :lol:

Anyhoo - to continue …

For those of you unfamiliar with toroidal transformers, what you have is a donut shaped thing with loads of wire wrapped around the tasty bit, some big washers, and a long bolt running through the hole to fasten it down to the casing. Really simple mount then?… only problem is that it is a potential minefield with actual explosive potential (kind of)

Basically this:

“Mounting: Toroidal transformers usually come with a long bolt, nut and a disk for mounting in the case (sometimes with extra rubber disks). Be aware of a metal case that the top of the bolt does not touch the top of your case. Since this bolt is already touching the bottom, if it touches the top too then via the rest of the case will effectively make a shorted turn around the transformer core itself, and damage will result.”

Source: https://electro-dan.co.uk/Electronics/wiringtrans.aspx

So my problem was that I had a situation where if anything inadvertently ended up being put on top of the amp it could flex the top enough to touch the bolt and cause the end of the f**king world (or summat worse …. a blow fuse for instance*)

As the amp was destined to end up in the shed, the chances of this happening could be rated at about 110% certainly, every time :eek:

*see this thread for one of many examples (https://www.diyaudio.com/forums/power-supplies/307081-toroidal-transformer-mounting-insulated.html)

So a genuine problem looking for a genuine solution.


hmmm, I thought, and more besides ….. for quite a while.

:hmm::hmm::hmm::hmm::hmm::zzz::zzz::zzz::zzz:

Toroidal transformers are quite safe to use, when the correct mounting hardware is used. A rubber washer a excellent insulator is mounted either side of the insulated windings
of the transformer Indeed a bolt connects the chassis through the centre, but it does not touch the transformer itself. the two insulators being air by considerable gap and rubber.

I have never known of any such failure of a toroidal transformer.

Barry
12-10-2019, 13:43
An alternative method of mounting, which would eliminate the risk of a possible short circuited turn, would be to use three or four heavy duty nylon tie-wraps passed through the centre of the toroid and corresponding holes drilled in the base of the amplifier case.

mikmas
12-10-2019, 14:23
Toroidal transformers are quite safe to use, when the correct mounting hardware is used. A rubber washer a excellent insulator is mounted either side of the insulated windings
of the transformer Indeed a bolt connects the chassis through the centre, but it does not touch the transformer itself. the two insulators being air by considerable gap and rubber.

I have never known of any such failure of a toroidal transformer.

The rubber washers are there to protect the coils from contact/pressure with hard mounting materials - they will not prevent a shorted turn:

From a toroidal manufacturer (there are plenty of such warnings online)

PRECAUTIONARY NOTES
SHORTED TURN CONDITION
A completed path by any conductor passing through the center of toroidal transformer, around the outside is a shorted turn (eg: the top of the mounting bolt shorted to the chassis). As with any short circuit, this condition will give rise to high circulating currents, and high heat. The transformer may be damaged beyond repair.

https://www.plitron.com/news/technical-notes/

Light Dependant Resistor
12-10-2019, 22:50
The rubber washers are there to protect the coils from contact/pressure with hard mounting materials - they will not prevent a shorted turn:

From a toroidal manufacturer (there are plenty of such warnings online)

PRECAUTIONARY NOTES
SHORTED TURN CONDITION
A completed path by any conductor passing through the center of toroidal transformer, around the outside is a shorted turn (eg: the top of the mounting bolt shorted to the chassis). As with any short circuit, this condition will give rise to high circulating currents, and high heat. The transformer may be damaged beyond repair.

https://www.plitron.com/news/technical-notes/

What is being attributed as a shorted turn poorly worded , is a condition of particularly small toroid transformers to exhibit a change to their flux density. Where with no loading
they indeed can see the middle bolt attaching as a means to heat. This is quite distinct from what is suggested by the shorted turns wording which should be
reworded correctly as flux density issues.

The shorted turn suggests to any reader a failure of the internal winding of the transformer shorting- and a reader jumps to the advice given
as seeing the attaching bolt as causing this, which is quite wrong, due to insulation.

The guidance for any mounting is to keep any field capable of conduction at least 5mm away. see creepage clearance https://sound-au.com/articles/mains-safety.htm#s5
and discussion of insufficient loading on particularly small toroids here: "The flux density in a transformer is greatest at no load, and it decreases as load is increased"
https://sound-au.com/xfmr.htm#s4

mikmas
13-10-2019, 00:48
The guidance for any mounting is to keep any field capable of conduction at least 5mm away. see creepage clearance https://sound-au.com/articles/mains-safety.htm#s5
and discussion of insufficient loading on particularly small toroids here: "The flux density in a transformer is greatest at no load, and it decreases as load is increased"
https://sound-au.com/xfmr.htm#s4

Fascinating stuff mate ... found this bit particularly gripping - had me right on the edge of my seat .....

"Weber (Wb) - magnetic flux. 'Flux' is the rate (per unit of time) in which something crosses a surface perpendicular to the flow. In the case of a magnetic field, then the magnetic flux across a perpendicular surface is the product of the magnetic flux density, in Teslas, and the surface area, in square metres. If a varying magnetic field passes perpendicularly through a circular loop of conducting material (one turn), the variation in the field induces a electric potential in the loop. If the flux is changing at a uniform rate of one Weber per second, the induced potential is one volt. This means that numerically the flux in webers is equal to the potential, in volts, that would be created by collapsing the field uniformly to zero in one second. One Weber is the flux induced in this way by a current varying at the uniform rate of one ampere per second. The unit honours the German physicist Wilhelm Eduard Weber (1804-1891), one of the early researchers of magnetism."

....totally absorbing

mikmas
13-10-2019, 10:03
... and swiftly moving on - some pictures:

Wired and ready to go:

https://live.staticflickr.com/65535/48889455938_9ee39132ea_c.jpg

The look of it:

https://live.staticflickr.com/65535/48890174487_73fc2326dc_c.jpg

Final resting place:

https://live.staticflickr.com/65535/48889995476_b6bae5510f_c.jpg

COMING UP NEXT .....
Final bits and bobs - and - what does it sound like?

Jimbo
13-10-2019, 10:05
:popcorn:

REXTON
13-10-2019, 11:01
Looks good. A very enjoyable thread.

Barry
13-10-2019, 11:28
Fuses in series with the speaker terminals are generally thought not to be a good idea. They can have a detrimental effect on sound quality.

Otherwise a nice, neat and tidy job. :)

mikmas
13-10-2019, 11:36
Fuses in series with the speaker terminals are generall thought not to be a good idea. They can have a detrimental effect on sound quality.

Otherwise a nice, neat and tidy job. :)

Thanks Barry :) .... the fuses are not my idea but recommended in the module specifications, so stay in :thumbsup:
(BTW - this was very much a 'cheap and cheerful' package in its day* - a very long way from 'high end' :lol: )

*In fairness to the original designer, the overall sound rivals the output from my Quad 405-2 admirably in many respects (and falls down in others - more later ....)

mikmas
13-10-2019, 11:37
Looks good. A very enjoyable thread.


Cheers Andrew .... we aim to please :)

mikmas
14-10-2019, 17:13
‘Things to do’ include deciding whether to leave the front plate I made plain or black. If plain, it will need a protective coating to deter oxidisation. The blanking grommet above the RCA inputs is there while I muse over fitting a pot or continue using a separate ‘pot in a box’ passive. I like the idea of it being more or less self-contained but the single input leaves it less flexible than external solutions.

I might also upgrade the speaker posts - these were a cheap 10-in-a-pack eBay purchase left over from an earlier project, so just about anything decent could be an improvement … but to be honest, the amp doesn’t have to be the last word in hifi excellence (or even come close) seeing as it’ll be mostly providing background tunes for shed type activities and not even remotely critical listening.

That said, the sound that comes out of this knocked together bag of bits ain’t ‘arf bad ... in fact, not bad at all. I auditioned the ILP concoction through my Quad floor standers in the house and it had no reason at all to feel embarrassed standing next to my 405-2. In fact, it beat the much more prestigious offering in some key areas and showed up some of the weaknesses in Quad’s legacy power amps.

Immediately noticeable was the abundance of bass slam and an overall forward presence that the 405-2 doesn’’t quite muster with the same RPi sourced material (noting that they both share a nominal 500mv input sensitivity). However, what the ILP gives in terms of thrust, it loses when it comes to subtlety; there is depth of tone there in spades and detail is not lacking in any register - but this comes at the cost of a slightly brittle top range that slipped into slight sibilance on some songs. Fine for the shed and some banging tunes while filing a ferrule - not so much for moments of contemplation and cosy coffee that require the euphoric euphonies the Quad does so well.

Anyhow - enough alliteration!! … time to wrap this one up.

Suffice to say, I have managed to salvage some 40 year old scrap and turned it into something that will give me daily pleasure … and thoroughly enjoyed the process :)

… and of course no thread like this should be brought to a close without a proper ‘before and after’ footnote:

https://live.staticflickr.com/65535/48898604321_740d82e5fc_b.jpg

brian2957
14-10-2019, 17:28
Wonderful work Mike , well done . I really enjoyed this thread :)

REXTON
14-10-2019, 18:30
Excellent thread! Now we need another... ;)

mikmas
14-10-2019, 21:01
Wonderful work Mike , well done . I really enjoyed this thread :)

Cheers Brian - very much appreciated :thumbsup:

Really glad you enjoyed the read - I enjoyed writing it :)

mikmas
14-10-2019, 21:03
Excellent thread! Now we need another... ;)

:lol: - will have to scrat around the attic and see of there's any more sow's ears .........