Download Ingot MkII

Ingot MkII
Upgraded external power supply board for Aragon electronics
The Ingot MkII power supply board is to date the only engineered upgrade solution
for Mondial's older Aragon line of components. It was designed specifically to be an
upgrade for Mondial’s IPS and Ingot external power supplies, replacing the original
board in those older power supplies. The Ingot MkII power supply board is a completely
hand-built replacement power supply board that was designed to easily drop into the
triangular steel housing of both the IPS and the Ingot external power supplies.
Before describing the Ingot MkII I think that it would be appropriate to identify the
different external power supplies which Mondial provided with their electronics and
elaborate on the specs of each unit. Each of the following power supplies provides +/24 vdc to the Aragon component that it is connected to.

The IDLK19 - Shipped with all early Mondial electronics. It was a small
black rectangular plastic package with the Aragon logo on the outside. It
featured a chassis mount 24 VA transformer, a voltage rectification circuit
consisting of 4 discrete 1 amp diodes for the rectification circuit and a total of
4,380 µF of internal capacitance. The power connector to the component is a 3
pin XLR.

The IPS - This unit debuted somewhere in the late 80's to early 90's and
was housed in the familiar triangular steel housing. It featured a PCB mounted
30 VA transformer, a single 2 amp bridge rectifier and a +/- 24 vdc regulator with
a total of 9,420 µF of internal capacitance. The power connector to the
component is a 3 pin XLR.

The Ingot - This unit was built specifically for the Aurum preamplifier. It is
identical in every way to the previously mentioned IPS except that it has been
beefed-up with more internal capacitance. In the Ingot, a pair of 10,000 uF
capacitors are installed after the bridge rectifier, in comparison to the pair of
3,300 uF capacitors that the standard IPS came with. Due to this the total
storage capacitance in the Ingot is 22,820 µF. The power connector to the
component was also changed to a 4 pin XLR. The reason for the change to the
4 pin XLR was to prevent users from accidentally plugging the power connector
into one of the Ingot's balanced preamp outputs. Internally only 3 of the 4 pins in
this XLR connector are used, so the same power is being supplied. Aside from
the difference in capacitance and XLR pin out there is no other functional
difference from this supply and the IPS.

The Ingot MkII – This board uses a PCB mounted 56 VA transformer, 2
amp discrete MUR series ultrafast diodes and discrete bridge rectifiers for each
voltage rail, for a total of 8 discrete rectifier diodes. A total of 35,200 uF of
internal storage capacitance. Heatsinking for the regulators, LED diagnostic
LED’s for the voltage rails and input/output terminals to eliminate the need for
soldering.
In building the new Ingot MkII the goal was to exceed the specs of ALL the previously
available power supplies that Mondial produced. I also wanted to add some features
that were absent in the original power supplies. All components used in the construction
of the Ingot MkII are brand new and sourced from major US distributors, i.e. Mouser,
Digikey, Allied Elec., etc. This is important because buying cheaper parts from small or
unknown distributors increases the chances for low quality Chinese knockoff parts to be
purchased, not a good thing! I also wanted this upgrade to be so easy to install that
anyone with a couple of decent screwdrivers and a pair of wire strippers could perform
the swap, no soldering required. To do this I used screw-down clamping connectors for
both the incoming AC power and the DC output voltage.
So how about the parts used in the Ingot MkII power supply? You will find that
throughout this power supply there are nothing but high quality parts all the way down to
the professionally-built FR-4 fiberglass board and the Cardas Quad Eutectic 4% silver
solder that was used to assemble the supply.
Let's start with the transformer: the original IPS and Ingot power supplies used a 30
VA-rated transformer capable of using either 120 VAC or 230 VAC 50/60 Hz to operate.
The Ingot MkII in contrast is using an upgraded 56 VA rated transformer (an 86%
increase in power output capability). This transformer is also capable of both 120 VAC
or 230 VAC 50/60 Hz input power just like the original, but unlike the original there is no
soldering required to make the conversion for AC voltage.
The Ingot Mk II uses MUR series ultrafast recovery 2 amp discrete diodes in the
rectification circuit. Not only does it use discrete diodes, but it also uses discrete bridges
for each voltage rail. The original power supply Mondial produced only had a single
bridge to feed both voltage rails and used standard-speed diodes. Green LED’s have
also been added to indicate when the +V & -V rails are operating, the original power
supplies gave no internal indication of whether they were working properly.
For the regulation circuitry the original Mondial power supplies used a 2 watt base
resistor in conjunction with a zener diode for voltage regulation. Both of those
components were then mounted in direct contact with the board. In the Ingot MkII the
base resistor was upgraded to a 3 watt unit and both the high power resistors and zener
control diodes were mounted approximately 1/8” off of the board to allow for better
convective cooling. This means that not only will they live a longer life they will also not
heat the board to the point that the board begins to discolor over time due to
overheating. The regulation transistors received heatsinks which provide about a 300%
improvement in cooling over the bare transistors that came in the original power
supplies. In addition to this, protection diodes have been installed across the transistors
to prevent a transistor failure.
Next, I want to talk about the capacitors used in the Ingot MkII. A lot of time was spent
in trying to find the best components here. Nichicon electrolytic capacitors were used
throughout the Ingot MkII because they are very reliable and they sound good. Directly
after the rectification circuit the 4 tall Nichicons provide 13,200 uF per rail, or 26,400 uF
total to filter the incoming AC and provide clean DC with minimal ripple to the regulator.
Some of you are wondering why I used 4 capacitors and did not stick with two larger
units to mimic the looks of the original factory power supplies. The answer to this is
simple, it is better to use two medium sized electrolytics than one large electrolytic in a
circuit because just about every measured parameter for that pair of capacitors will be
better than if a single capacitor was installed in their place: ESR, ripple current handling,
Impedance, etc., all are improved. The reason most manufacturers do not use multiple
electrolytic caps in their power supplies is plain and simple, it costs more money and
takes up more space.
The capacitors after the regulator circuit continue with this same rationale, more is
better. You will notice that 4 electrolytic capacitors per rail are used [8 total] on the
output side of the regulation circuit. Once again the reason is that four 1000 uF Nichicon
Audio grade electrolytics would provide a much higher performance filtering bank than
the original three 470 uF caps used in both the IPS and Ingot power supplies. In
actuality only 6 of the 8 caps are used on the output of the regulator. Two of the eight
capacitors are used for the transistor base filtering in the Ingot MkII and in the original
IPS/Ingot supplies two of the six small caps were used for this same function. On the
Ingot MkII’s regulated DC rails a pair of Wima MKP2 metallized polypropylene caps are
installed as bypasses. None of the original power supplies Mondial produced came with
bypass capacitors of any type in them.
Every Ingot MkII I hand-build has been fully bench tested and then burntin/auditioned powering an Aragon component. It will work on any of the older Aragon
equipment that used the external power supply, i.e. D2A, D2A MkII, 24K, 24K SP, 47K,
18K, 18K Mk II, & Aurum. The Ingot MkII carries a 10 yr warranty from the date of
purchase. If anything happens to it during this period of time email me at
[email protected] (owner responsible for shipping both ways) and the unit will
be fixed free of charge. Your new Ingot MkII is just about bullet proof, it will very likely
outlast any of the Aragon electronics you decide to power with it.
About myself, I have over 24 years of experience working for ST Microelectronics &
National Semiconductor as a semiconductor equipment engineer. Over the past few
years I have been working for a large state university in their electrical engineering
department as a staff engineer. I do not consider myself to be an expert in electronics
design, but I do have more than a passing familiarity with electronics and electrical
systems.