Trace Elliot AH1000-12 schematic needed

[Roberto]

Ouch! The one you linked doesn’t ship to Italy. I will search more. Thanks!

[J M Fahey]

Why would you buy water heater resistors outside Italy, a *most* Industrialized Country, is beyond me

I´d check one of these:

http://www.thermowatt.com/it/categor...nze-scaldacqua

https://www.riscaldatori-elettrici.i...sione-liquidi/

https://www.riscaldatori-elettrici.i...er-immersione/

http://www.tre-c.it/everwatt/prodott...er-immersione/

http://www.mdrmarca.it/prodotti/prod...che-per-acqua/

of course, you ask for the raw element, no thermostat.

[Roberto]

a *most* Industrialized Country

We could start a bi-logue (does this exists? ) about how the industry delocalization of the last decades, following the cheapest manpower, lead to loss of know-how in the G7, but I'll simply answer to your question: I'm a Mechatronic Engineer with a specialisation in food and beverage processing and a passion for electronics. I'll use this heater to test this power amp and most probably nothing more in the rest of my life. In Italy the standard contract for each apartment is 3 kW, and the standard heater is around 2 kW (to permit to use something else while heating the water). So I need at least three. Consider then that I would have to buy spare parts, that usually are sold with at least a 300% margin on them. This make the price of the final dummy load something like 10 times the cheap chinese one, and I'm not so sure it wouldn't be chinese and resold. So 15 euros are ok to test once the power amp, while 150 euros are not (it would cost more than the power amp to test).

That's all.

[Roberto]

Thanks for the update links Juan Manuel,

in the meanwhile I've receipt the power amp (I've already have the caps, so I bought it without them) and the toroidal HV transformer (20 euros each from a company close to me) with three taps on the secondary: 200-260-290 Vac (to be able to choose different working points of the preamp). I'm waiting for the power supply then I'll assemble everything.
Here comes the photos.

[MarkusBass]

I use such resistors (4 connected in parallel and attached to a big heatsink): http://it.farnell.com/welwyn/wh100-1...15r/dp/1768209

[Roberto]

Thanks Markus,

unfortunately for this PA they would not be enough, and to buold a load with those I would pay 8 times more.
Those are perfect to dissipate power on guitar dummy loads.

[MarkusBass]

I'm sorry. I haven't noticed how much power you need to dissipate.

[Roberto]

First step: weight loss.

[Roberto]

I'm sure that in an amp in big series there's a reason, but why this part of the amp is supplied at 14V?
Thanks

[Roberto]

Is anyone aware of the reasons why I can't use two diodes in series (or even tapping it from the +15V) to drop 1,2V instead of the 22 Ohm resistor and the 47 microfarad capacitor?

[Tom Phillips]

Yes. The resistor and capacitor form a decoupling Network between the two sections of the circuitry. The diodes would only drop the voltage.

[Jazz P Bass]

I'm sure that in an amp in big series there's a reason, but why this part of the amp is supplied at 14V?
Thanks

[ATTACH=CONFIG]49477[/ATTACH]
[ATTACH=CONFIG]49478[/ATTACH]

The +14Vdc is the supply for the LEDs.
The opamps 'sink' the voltage to turn the LEDs on.

[Roberto]

Thanks Tom and Jazz.

Can you please explain me why is needed to supply the leds with a decoupled supply?

Just some noise while turning on and off the leds, or it is because when leds will turn on, the current increases (almost doubles) and the reference for the red light come sooner? Something to make the user not to overload the power amp for long periods, but lower the level even more than needed (the temporary lower voltage reference of the comparators) then back to normality.

[Roberto]

One more step:

[Roberto]

Do you guys suggest to add "sponges" before the fans, to filter out the dust from the cooling air?
I see pros, main one is of course is avoiding dust inside the rack, and cons, main one is that while the filter is clogging, the fans will move its working point towards the left of the curve, reducing the airflow.