MDA-400 (Some hidden features)

[AP2]

Hi,
I would like to make known to DIY, this class D amplifier, in particular some circuits that use. Some are already familiar with the definition in the high range of this amp, I would like to explain how it is obtained even if it is to be considered an entry level amp. Another reason for my presentation is that you can purchase this kit at a very low price, this message is also directed to any company considering the high amount of stock. Moreover, this is possible because AP has released this product.
well, now some features:
Class D PWM fixed frequency (400kHz) pre and post filter feedback (with slope filter in series)
Driver IC: IR2110
MOSFET: FB38N20
Gain: 27dB
Frequency response: 10Hz to 40Khz (-1dB)
Measure reported at 230VAC:
Power Output: 370W RMS (400Hz SIN) @ 4R
Power Output 640W RMS (400Hz SIN) @ 2R
Burst 33-66ms 1Khz 400w @ 4R
Burst 33-66ms 1Khz 700w @ 2R
SN / N 102dB (weight)
THD: 0.02% 200w @ 4R; 0.04% 350w @ 4R
This amplifier can be used normally at 2R in the case of active sub, without add heatsink.
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Meanwhile, the simple protection of the output stage Vs.current load.
In this recent years has proved effective and robust protecting the amp short circuit on the load, thus helping the response to reactive load.
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short, some parts of the schema (as special ALC) and audio measurements.

Regards

[AP2]

While i describe diagram/solution of this amplifier, i show also step by step a nice modern solution, up to complete Amplifier fully finished.
This chassis has been designed to achieve low emission (EMI/RFI,noise).

Next step some circuit, and bank capacitors low capacity/ESR.

Regards

[theAnonymous1]

This should be moved to the Vendors Bazaar section.

[AP2]

Originally Posted by theAnonymous1

This should be moved to the Vendors Bazaar section.

If it is correct to move,np.
independent if anyone is interested in this amp, my thread wish to present the solutions adopted in the scheme of this amp and discuss. this is reason of my thread.
...just in 10 minutes I was putting some parts of the scheme, maybe someone needs to see how it develops a good amp..


regards

[AP2]

I have always paid special attention to the protection circuits.
not enough to have a good current sensing device if then are left out some important functions, such as when in the presence of short circuit (or other protection that caused the shunt down) the amplifier tries to get back in operation. in this case, the volume already high, certainly lead to the destruction of the amplifier. I predicted then, in the case of protection, mute is inserted on the input circuit, releasing soft when he tries to leave.
The start sequence is composed of: enable driver-> ceck presence at DC output-> activate relay-> release mute. in case of protection, this performs inverted. disable driver-> disable relay-> insert mute.
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This amplifier has been develope in 2005 for a French company with precise specifications. before being accepted, was compared with the amp on the market.. yes...accepted full production up to 2009. now free.

[AP2]

Hi,
Add some work on the frame (holes for the cables), implements
Bank capacitors 5000uF per rail. (effective at 30 ° is 3750uF)
tomorrow place the block diagram (global), before adding other segments of the circuit diagram (for better understanding).
at last, audio measurements and impressions of some people who have listened to in various rooms of high fidelity listening in stores, comparing it with 200W class AB amplifier. (hope want post )
This amplifier include ultra low thd preamplifier. 27 dB ref to loop of NFB.
Size and appearance, they are a little amplifiers amatorial (in my opinion) is considered, which is a dual mono with high quality parts.

Regards

[AP2]

Hi, sorry for delay, i'm busy now. at short put complete diagrams of MDA-400. (Aluminum side bars (50mm height) added).
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I realized from the diagram, only the protection circuit (for which I received a few pm), maybe it can help some diy to create a small pcb.
than the protections available in kit form, it works with single supply voltage, and is very reliable. can be added to the schema of the protez. short circuit on the speaker (schema first post).
if someone wants to make it, I'm available.

Regards

[AP2]

Features of protection circuit:
Relay switch after 2-3 sec. (from power on) and turns off immediately (200ms) when you turn on the power. provides the DC offset and temperature protection.

[AP2]

Hi,
Just a summary of the blocks that make up the amplifier.
the first stage can be set for different sensitivity input.

A few words on the "slope filter". this is one of my drawings, the main reason is to keep clean the harmonic component in the output, according to the load variation.
simple description:
Under a flat response, this stage adds a small positive feedback, according to 27 dB of the loop. (as balanced gain).
When a variation of the load (real time) also due to the presence of a particular musical instrument, the difference of the output response unbalances this circuit and obtains (by difference) a negative feedback. the range between positive and negative, it is sufficient to keep within 1dB from 4R to open load. In addition, this amplifier has a very clean output harmonic content.
next step, I describe the comparator, why i use two in parallel.
this amp is complete with all the functions as a finished product,
including the LED flashes for 3 sec. when we turn on. full protections with gold relay contact.

regards

[AP2]

Hi, Mono version same parts/Amp and...performances
well, just a time i prepare scheme and show all of this amplifier.

I insist that better of 1000 word's or marketing strategy (or measures audio false) is try an amp. specially on serious loudspeaker with low reactive load, this is good way for see all. independant if after play on active way.