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Mono/stereo enhancements


Normally our CS-40(ps) is provided with a pair of power transistors. With those we can make around 150 - 250Wrms of clean power, depending the type of Mosfets used. For some, this is not enough and others simply don't believe that one pair is enough based on the fact that others use multiple pairs. Correct, but these need to be paralleled because the have way less quality than the ones we use. For technicians: ours don't have a poor SOA, actually none! Just Umax=200V, Imax= 8 or 16Amps, that's it. Ours won't brake down easily as so many other Mosfet designs tend to do. They have a
real bad SOA, causing an inevitable paralling multiple pairs.  if we were marketeers, we would try to sell you more, but we are (audiophile) technicians -)

Now you are aware us beeing technical: these extra modules bring some advantages though like better speaker control, more (solid) bass fundament etc. But, more is not always better.
Mosfets as we use are fantastic components, but as always have a minor mishap called the gate capacitance. This gate capacitance is truly a capacitor value measured on the control (Gate) pin of the mosfet. This "mishap" is what's keeping lots of manufacturers away from Mosfet designs, since if you're not designing correctly, the amplifier will start to oscillate and burn itself up and most probably your speakers (tweeters) as well.
With our PCB designs and schematic structure this effect won't happen, as prooven by the many amps we ( and quite some DIY'ers) have built by now.

While adding extra mosfets this capacitance rises with the number of mosfets used. This capacitor value has to be "(dis)charged", causing a slower functioning amplifier, or in technical terms: the slew rate will go down. Happily our amps are that fast that even with four pairs they are still way faster than the best circuits in mixing gear, etc. But, you probably will notice some difference in "attack" though. As always in nature: you win some, you loose some.

With all our CS-modules you could add a single pair of mosfets left and right of the CS-module directly from the start already. But, with thosde you need to increase the depth of your am;ifier from 300 to 400mm. Not everybody is fond of that and some others lke to use more mosfet pairs for numerous reasons like higher power reserves, different cabine shape, more impressive looks, etc. So far, we couldn't make something like this.
As we list somewhere else, we are always adopting new ideas and one of them became active in January 2018, where we modified both CS-40 and CS-40ps boards in a way that we can mount some connectors instead of the power transistors. With the "bare" boards (Suffix CB) there are connectors instead of these power transistors, meaning that you require an extra module where these are on. Since we still are in the developing phase, we can only show some drawings of them:

The 2 pairs type in 80mm height, also available in heights of 120 and 165mm with similar layouts as below.
The 2 pairs variants have the same width as a CS-40(ps): 208mm

The 3 pairs type in 120mm height, also available in heights of 80 and 165mm with similar layouts as above / below.
The 3 pairs variants have a width of 296mm, just fitting in a MODU Dissipante, 300mm deep.


The 4 pairs type in 165mm height, also available in heights of 80 and 120mm with similar layouts as above.
These 4 pairs variants have a width of 350mm, so truly huge! The one above is 350x165mm.
This one would require f.e. a MODU 450x210x400/500mm (WxHxD) cabinet.

All NINE (3 heights x 3 lengths) possible models ar available with both Hexfet types as well as both Mosfet types we use.
A quick calculation: 3 levels x 3 heights x 4 transistor types brings us to 36 different possibilities.
Then we are not talking about the use of different types and quality of the mounted supply capacitors....
Most of the price of these modules comes from the type of capacitors used by the way. There are a lot.

We also have models with 2-4 pairs without capacitors and safety relay, where you save a lot of money.
Since we believe they will be used in classy PA amplifiers only, we supply them with rugged Hexfets only.

Since with these extra boards there could flow larger currents than CS-40(ps) can handle, the power supply
voltages from the power supply are fed directy to these extra modules. Safety relay(s)
disconnect with the power on/off switch or if a protection module becomes active.

Below the graps where the possible output level is given regarding the transformer output voltage:

And this one shows the output while driving these setups in bridged mode:

Note that the outputs of Hexfet based electronics are around 10% higher, due to lower internal losses.
With these modules, the avaialble power will be strongly depending on the Power Supply capacity
and the heat dissipation factor of the heatsinks / enclosure.  

As with all our modules we don't "schrink" the PCB's in a way where all just fits as we see everywhere, resulting in heat building up and way too small tracks. All the basic rules in PCB design are ingnored with those kind of PCB's. We see 1mm tracks leading the currents to a 16A Mosfet. Nice, but a 1mm track can lead way less amps than this 16A.... But, it's small indeed. And then, its placed in a cabinet where you can't find this tiny board any more, all empty space, why? And then this: outside the amplifier you spend a lot of money in huge and very specific speaker cables, inside the amp there are 1mm tiny tracks leading the same signal. To us, this makes no sense at all.
We do it the other way around: we take a (high quality, double sided FR4) board which just fits in the required / planned cabinet and spread the components over it. The cabinet space is available anyway, air can flow freely around the components, we have less heat building up and due to way wider tracks we have a better performance, just by a clever PCB structure. Also here no electronic compensation required as normally required in multiple power transistor designs in order to prevent a so called "thermal runaway". The negative temperature coïficient of our HEX/mosfet power transistors insure an equally spreading of the total current over all the transistors used, by nature only. Example: if a power transistor heats up, it's internal resistance increases a tiny bit, causing  lower current in the device. The somewhat lower current lets it cool down a bit, etc. After just a few minutes our amp is completey stable due to this, so we don't need to take extra precautions with extra electronics AND you can start listening right away. There is also NO need to have your amp on all the time, please don't for earth sake. Actually, even with quite some power it will become only handwarm while mounted it the suggested cabinets.

This one makes fun: Please note that a bridged mono amplifier with four pairs of power transistors could drain about all the available 16 Amps from your power grid while using it at full power with heavy bass sounds !

READ MORE about CD-40 GDS/GSD80        CD40-GDS/GSD120        CD-40 GDS/GSD165        CD-40 GDS PA

We strongly believe that these powerful add-on's will fill the need of truly everybody. They will provide absolute clean, "unchopped" audiophile power.