power amp help please

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Hi Audiosan.
Yes off load they only see approx 10 volts so no problem there .. My concern was , What is the point of doing the supply like this if it is not isolated from the main supply rails . Will the higher voltage rail not be modulated to a degree when the main supply is being asked for current?

regards Mark
 
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Yes, but you will be able to drive the outputs much closer to the rails.

They should have added a Baker clamp to prevent saturation in the output stage.

BakerClamp.gif


This is the APT and it has the same rail voltages as your amplifier.

(Vas, predriver and driver stages only)
 
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............... it only uses two 3300uF caps in parallel per rail to feed two channels. They look real small too for this power level . ...........
This smoothing capacitance value has little to do with power.
It has to do with duration and amount of the current demand.

Driving bass signals gives long duration current demand. That depletes the charge during the time gap between mains' re-charging pulses.

If the amplifier were used for driving Mid and Treble only, then these signals tend to be of much shorter duration (particularly so for Treble) and the total charge sucked out during the non-recharging period is generally much smaller.

Check the High Pass filter fitted at the input to the amplifier. If this attenuates the bass signals, then 6m6F shared between two channels may be perfectly adequate.
 
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Hi Audiosan.
Yes off load they only see approx 10 volts so no problem there .. My concern was , What is the point of doing the supply like this if it is not isolated from the main supply rails . Will the higher voltage rail not be modulated to a degree when the main supply is being asked for current?

regards Mark

the main reason, probably the only reason is cost. 16V caps is so much cheaper then 80V caps:)
 
Hi djk.
I dont care much for getting the output closer to the psu rails . thia amplifier has way much more power than i use or need. My main listening speakers have a 91db sensitivity. they are bipoles the manufacturer states they are 8 ohm amplifier compatible . they use two 8 ohm woofers in parrallel and two 8 Ohm tweeters in parallel per cabinet. so i would state the speakers are 4 Ohm impedance. anyways they are very easy to drive and have never seened to pose a problem to any amlifier. ok bottom line does this amplifier stand any chance of being a decent HiFi amplifier ?
Best Regards Mark
 
Hi Andrew .
The amplifier does have a high pass filter 40 hz as stated by the maker. The maker also states that if using the built in crossover option it is best practise to use the internal amplifier for the mid and high frequencys . All this imformation is in line with what you posted .Also i am not a fan of just chucking loads of mF at a psu just for the hell of it . Just enough for the job in hand + a little extra to allow for the caps aging . Ps that low pass filter will be removed .

regards Mark
 
Hi Audiosan .
Even with my not so expirienced eyes i can see a lot of cost cutting in this amplifier. PSU wires not twisted together. low level audio , a signal from the output to drive the output meter and two 73 volt dc rails all running in a small ribbon cable . All this can not be good for sound quality?.
regards Mark
 
..............that low pass filter will be removed .............
NO !
That Low Pass filter may be the last component that allows the amplifier to operate properly with the frequencies that get in.

Similarly for a High Pass filter.

You must look at the remainder of the amplifier and assess if it is capable of operating with a wider bandwidth signal. This is really important.
 
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.....If u can Help Me To Know Unknown IC & Parts Numbers. How about the Sound & low pass This amp.
thanking for the Helping me
If you want assistance with Apex Audio's designs, you should search his thread for it with the search button at the top of the page or start a new thread if you want to discuss it or AlexMM's PCB design. It is not being discussed here.
 
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