Ben's One4 (WONFOR) SECA build (ready-populated boards)
Firstly, many thanks for Colin. The man clearly designs some of the best amplifiers around. Certainly the best I've ever owned.
Secondly, many thanks to Colin. That he makes such quality available at such
affordable prices reflects his qualities as human being. In the case of
my build, this is doubly so as I have gone for the
hand-populated-by-Colin boards. At £100 per board this is value that
makes me feel a bit guilty. On top of this, Colin is extremely generous
with his time in supporting builds of his amps.
Next, I've been asked to provide a list of parts that I have found to be required when
building the amp using the ready-populated boards (obviously starting with upopulated boards requires all the electronic components). I am compiling the parts list for my build below. As I
am only just starting the build today it is likely there are parts that
I will find I need as I go (currently Rumsfeldian "unknown unknowns"). I will edit the list below as and when
these come up. Please inform me of any errors and I will correct.
There are obviously other options for parts, possibly better, possibly cheaper. The ones listed below
are simply the ones that I went for. I have included links wherever
possible. Prices are correct for summer 2015.
So far I have purchased:
2x populated boards from Colin (he kindly fitted aluminium strips to each
to allow for attachment to the double heatsinks on the Modushop case
that I went for (see below)). Cost (2 x £100 = ) £200 + £5pp
1x modushop case (including heatsinks and feet) £187.77 (258.64 euros) including VAT and pp
2x TRANSFORMERS, TOROIDAL, 2 X 18V, 225VA (The BOM states 15V, but Colin advised me that given the capacity of the heatsinks in the modushop case that I'm using, 18V trannies are fine.) (2 x £37.78
£90.65 inc VAT & pp
4x 4pos terminal block (4x £1.43) = £6.86 inc VAT & pp
Heatsink grease (probably too much!) £3.19 inc VAT & pp
2x phono plugs £2.99
4x speaker terminals £6.90
M4 self-tapping screws (for attaching boards to heatsinks).
Also some mains cabling, mains plug and I'll need some internal wiring to connect to the speaker terminals.
So total cost of parts so far is under £510.
Seems like a bit of bargain, if it sounds anything like my TOCA!
Now on to the build!
Secondly, many thanks to Colin. That he makes such quality available at such
affordable prices reflects his qualities as human being. In the case of
my build, this is doubly so as I have gone for the
hand-populated-by-Colin boards. At £100 per board this is value that
makes me feel a bit guilty. On top of this, Colin is extremely generous
with his time in supporting builds of his amps.
Next, I've been asked to provide a list of parts that I have found to be required when
building the amp using the ready-populated boards (obviously starting with upopulated boards requires all the electronic components). I am compiling the parts list for my build below. As I
am only just starting the build today it is likely there are parts that
I will find I need as I go (currently Rumsfeldian "unknown unknowns"). I will edit the list below as and when
these come up. Please inform me of any errors and I will correct.
There are obviously other options for parts, possibly better, possibly cheaper. The ones listed below
are simply the ones that I went for. I have included links wherever
possible. Prices are correct for summer 2015.
So far I have purchased:
2x populated boards from Colin (he kindly fitted aluminium strips to each
to allow for attachment to the double heatsinks on the Modushop case
that I went for (see below)). Cost (2 x £100 = ) £200 + £5pp
1x modushop case (including heatsinks and feet) £187.77 (258.64 euros) including VAT and pp
2x TRANSFORMERS, TOROIDAL, 2 X 18V, 225VA (The BOM states 15V, but Colin advised me that given the capacity of the heatsinks in the modushop case that I'm using, 18V trannies are fine.) (2 x £37.78
£90.65 inc VAT & pp4x 4pos terminal block (4x £1.43) = £6.86 inc VAT & pp
Heatsink grease (probably too much!) £3.19 inc VAT & pp
2x phono plugs £2.99
4x speaker terminals £6.90
M4 self-tapping screws (for attaching boards to heatsinks).
Also some mains cabling, mains plug and I'll need some internal wiring to connect to the speaker terminals.
So total cost of parts so far is under £510.
Seems like a bit of bargain, if it sounds anything like my TOCA!
Now on to the build!
Comments
I put the cases together this morning.
Fairly manageable.
Only difficulty that I had was that whilst the Modushop instructions are clear enough in showing what slots into where, it wasn't clear to me which screw / fixing to use at each point, so there was a bit of intelligence / experience / trial and error required. Got there in the end...
Plenty of room inside. A more skilled and experienced builder could probably manage with much less. But it's reassuring to me, a complete novice, to have a bit of elbow room in there to allow my big clumsy hands and screwdrivers a bit of space to fiddle.
OK, 1st slight issue has arisen.
If I place the board against the heatsinks so that the board's attached aluminium strip is flush to the heatsinks thus...
...the angle at which they stand between the bottom plate and the underside of the case's metal strip is just too shallow for their cute sticky plastic feet (fitted by Colin) to anchor on to the heatsinks for stability (see here....)
Should I get some new feet, or simply attach some sort of little plinth against the heatsinks for the existing feet to attach to?
A few more questions to you and others as I'm thinking about things...
1. Drilling the case: Is it best to this with the case assembled, or should I mark where the holes should be and then dismantle the pannels prior to drilling.
2. Drilling the boards' aluminium strip: I'm nervous about this. Should I be...?
3. M4 screws for securing the boards to the heatsinks: The boards' aluminium strip is 3mm, the heatsinks are 8mm. Which length of M4 screw is advisable (6, 8 or 10mm) for screwing these two together?
4. Wiring in the toroids: No idea how to do this. Any advice / pointers to good Youtube tutorials would be much appreciated.
5. Mains cable grommet(?): I want to go for a captive lead (not IEC). What's the best way to secure the cable as it goes through the rear pannel?
6. Wiring to the speaker terminals. I'm feeling thick about this one. From where on the boards do I take their output?
7. Earthing. There is an earthing point on the boards. Quickie also pointed this out previously. Is this the only earthing point I need, or do I need to connect something directly to the case itself?
All input gratefully received. :-)
Is this place a community or what?
Just had a personal call from Quickie answering all of my above questions, and a few that I hadn't even thought of. He may even have thrown in a few tips on how to bake the perfet souffle.
I feel that wisdom has been bestowed upon me!
Thanks Paul!
=D>
However, I may have scribbled them down / remembered them wrongly, so please let me know if I've made any errors and I will correct them. This request is especially with regard to the but concerning mains wiring!
Most importantly, I am not experienced in electronics so please interpret this post as a recollection of what somebody said to me; and not as instructions for wiring up an amplifier.
With regard to attached self-adhesive foot being too short. Paul suggested that these are called "PCB standoffs". They are also variously called "PCB feet" and "PCB pillars" depending on which manufacturer or shop one looks at. I can't see that any of that exact type are long enough for me (40mm). So I may have to improvise with something similar, or use the existing foot and pack out the gap with something.
For the othe questions:
Q1. Drilling the case: Is it best to this with the case assembled, or
should I mark where the holes should be and then dismantle the pannels
prior to drilling?
A1. Paul didn't feel especially strongly about this either way. However, after discussing it with him I realised that I will have to dismantle the case as there won't be room to drill the holes in the heatsinks in the assembled case.
Paul made a few general recommendations for drilling the panels. Firstly to place a piece of scrap wood underneath (this makes the exit of the hole neater). Secondly, to tap a small indent prior to drilling to reduce the chances of the drill bit slipping. Lastly, lubricate the bit with WD40 prior to drilling.
Q2. Drilling the boards' aluminium strip: I'm nervous about this. Should I be...?
A2. No. Just take reasonable care. The alumninum plate is well away from the PCB. Paul suggested 4 holes in the aluminium strip (1 towards each of the corners).
Q3.
M4 screws for securing the boards to the heatsinks: The boards'
aluminium strip is 3mm, the heatsinks are 8mm. Which length of M4 screw
is advisable (6, 8 or 10mm) for screwing these two together?
A3. 8mm. Paul thought the M4 Taptite screws were perfect. My own understanding is that M4 taptite screws require a 3.6mm drill bit hole.
Q4. Wiring in the toroids: No idea how to do this. Any advice / pointers to good Youtube tutorials would be much appreciated.
A4. The Violet and Grey wires are simply connected to each other. The Brown and Blue wires go to the mains wires. The Yellow, Orange, Red and Black wires go, in that order, to the points, left to right on the green connector (AC 0C 0C AC) on the PCB board (see below) using one of the green 4pos terminal blocks.
(Please contact me if I have remembered this wrongly!)
Q5.
Mains cable grommet(?): I want to go for a captive lead (not IEC).
What's the best way to secure the cable as it goes through the rear
pannel?
A5. A conduit gland or gromment. I haven't looked one up yet, and will ammend here when I do.
Q6. Wiring to the speaker terminals. I'm feeling thick about this one. From where on the boards do I take their output?
A5. Using a 4pos terminal block connect to here (see below)... Either of the 2 points on the left ("OUT") connect to the red speaker terminal, and either of the 2 points on the right ("GND") connect to the black speaker terminal.
Q7.
Earthing. There is an earthing point on the boards. Quickie also
pointed this out previously. Is this the only earthing point I need, or
do I need to connect something directly to the case itself?
A7 The "earthing" on the PCB is the return for the speakers, so yes, the case needs to be earthed inside the case near to where the mains cable enters. Paul recommended using a ring crimp to do this.
Paul also recommended putting in a switch. Possibly one per channel. He pointed out sourcing a switch that requires a round hole on the case would be advisable (I don't have the tools to create a square one).
In addition Paul recommended inserting a fuse inside the case prior to the toroids. (And, before the switch?)
Hope that helps. I will ammend this post as further details fall into place.
Happy to have a soya burger with salad, mayo, chilli sauce and ketchup if that helps...
I think I've sorted a work-around this morning. If that doesn't work out like I hope, your idea sounds like a good plan B.
Many thanks. =D>
I really enjoy seeing all the ingenious ways of working around these obstacles.
Also wonderful to read of other people's love affairs with Araldite. I think most of my house is now held together by it!
My own plan to secure the boars arrived from Farnell this morning. It's just some spacers that provide an extra 25mm of height to the feet Colin supplied with the boards, and more importantly a few more degrees of angle. They seem to work fine.
(I may Araldite the feet to the case to ensure they remain secure...
And look, there's my hammer too. My hammer for smashing things that refuse to work as I demand.
Look at them bastards. B-)
I feel as I imagine did Brunel as he looked upon the Clifton Suspension Bridge.
Everything went pretty smoothly. Paul's tip about tapping a small indent on the heatsinks at the drilling point to anchor the bit was definitely worth heeding. And my new 3.6mm bit was bang on for the M4 taptite screws. The taptite screws themselves went into the heatsink holes like a knife trough butter; so I can recommend those.
I did break one shitty old drill bit when drilling through the aluminium plate (I wanted those holes to be slightly bigger obviously), the drill came down on one of the fuse holders on the board and bent one of the clips slightly, but that was easily reshaped. Hopefully no damage done...
I haven't applied the heatsink grease yet, so will need to unscrew the boards to do this before they're finally secured and the feet permanently attached.
Anyway feeling pretty pleased with myself! (Due simply to my low (realistic) expectations of my own abilities!)
(Give me a shout if you need a hand with your next project. B-) )
I'm dead keen to know people thoughts when their amps start to produce music.
Have you got all the plugs and switches on the case yet?
That's what I've been doing today actually. That and securing the boards using heatsink compound. (And, of course Aralditing the feet!)
Reasonably happy with results. Though I managed to scuff up the back plate a little during the drilling / de-burring...
Quite enjoyed the metal working tho! Some improvisation needed. The thread on the mains cable gland that I'm using was bigger than my largest drill bit, so I had to drill small holes to cut around the perimeter in order to achieve a wide enough opening. The nut of the gland covers well the rough edges, so all good....
One question re the phono sockets....
They came with plastic spacers and a sort of metal tag ring on to which the shield / return is soldered. Does it matter which side of the internal plastic spacer, the metal tag ring goes...?
Also, I've dicked around with the current adjust on the PCB board. I have a multimeter to get it back to the rating Colin has advised, but haven't a clue how to do it. Colin's busy today, but I'll call him tomorrow when I'm hopefully finishing up with the connections and soldering...
Metal tag needs to go on after the plastic spacer ( plug body needs to be insulated from the case)
Set current adjust fully anti clockwise before powering up.
Set meter to mv dc and connect leads across R11 the 0.1R 3W resistor.
100mv (0.1v) across resistor is 1 amp standing current 0.2v = 2 A etc.
Your sinks look big, so can probably set this quite high, Colin will advise.
Don't forget your mains fuse.
Paul, thanks for the advice on the adjust. Will return to work tomorrow and see how I get on.
And rest assured, the fuse holder is in place: You can just about see it underneath your switch in the first photo in my last post (connected up with your purple wire). Haven't put the fuse in yet, but will do!
And for James...
I'm stuck. (It hasn't taken much.)
I'm not sure which is the 0.1R 3W resistor (R11). I googled it, and found images but can't locate it on my board...
Also, which is the best setting for measuring mv dc on my multi meter...?
Don't rush that cha!
(My meter has just the metal points.)
Perfect. =D>
Many thanks.
Final question...
As this is a voltage measurement, I'm imagining that this is a reading that I take with the boards powered up...?
I'll pop to Maplins and get some clips.
Colin had set the boards up perfectly. Like an idiot I fiddled.
Will I need a speaker connected to the channel I'm testing?