500W PA amplifier with Limiter

[hadita]

APEX Hey I'm interested in seeing B500 f 32 NSL have any trouble getting replacements from what we could t

I

 

[hadita]

Hello I am interested in Mount B500 essibiboi but here it is difficult to achieve in the regular LED NSL32 module if you are using does not affect the performance of power....

 

[eesbiboi]

It's same as for H900 post #405 in thread:
http://www.diyaudio.com/forums/solid-state/162408-900w-h-class-pa-amp-limiter-41.html
Regards

apex...
sir...
today i replaced op amp NE5532 with new one and zeners too...
i've checked 2n5401 2n5551 mje340 mje350 c4793 and a1837 they were all fine...
dc is still present at the output...
still power turn themselves hot in less than a minute...

 

[Tube Pro]

Hi Apex,

Is it possible to change R23 (330 ohms) to a variable resitor like 500 ohms to adjust bias and crossover voltage?

Regards,

Joel

 

[mihailo]

You need to put tin on your lines! Maybe you have problem with conductance!
Also measure transistors to see are they all ok.
Then look at your power supply cables too.
Measure bias.

 

[mihailo]

Hi, Hadita.
I haven't put anything instead of NSL32, and it works fine.
You don't need NSL32 for amplifier to work.
Regards

 

[Tube Pro]

Dc output

apex...
sir...
today i replaced op amp NE5532 with new one and zeners too...
i've checked 2n5401 2n5551 mje340 mje350 c4793 and a1837 they were all fine...
dc is still present at the output...
still power turn themselves hot in less than a minute...

@ Ees,

Hi friend, you may need to test your module with a lower voltage and current, not the 25A. Getting hot output trannies usually indicates high bias current. Something should be wrong in the circuit.
Have you matched those outputs? Though not always a big deal, but it always helps maintain a well balanced transistor function.

 

[mihailo]

Eesbiboi, look at picture.
regards

 

[Tube Pro]

Nsl32

Hi, Hadita.
I haven't put anything instead of NSL32, and it works fine.
You don't need NSL32 for amplifier to work.
Regards

It's true,

NSL 32: this device together with its related parts will prevent your amp from clipping or overdriven beyond its capability.
It decreases input impedance allowing small amount of signal going into the 1st stage OP Amp, when the circuit senses an over current / voltage at the output / speaker terminal.

 

[apexaudio]

I also had DC voltage about 8V, when start amplifier first time,
but when I turn it on after few seconds again voltage was -35mV.
And now is 35-40mV and amplifier works ok.

Usually DC offset on output is 4-8mV in my expirience without any matching and adjust, and it is stable (bias, temperature) with or without speakers on output.
Regards

 

[apexaudio]

apex...
sir...
today i replaced op amp NE5532 with new one and zeners too...
i've checked 2n5401 2n5551 mje340 mje350 c4793 and a1837 they were all fine...
dc is still present at the output...
still power turn themselves hot in less than a minute...

Do you measure other DC voltage points? Outputs must be cold without bias.
Regards

 

[apexaudio]

Hi Apex,

Is it possible to change R23 (330 ohms) to a variable resitor like 500 ohms to adjust bias and crossover voltage?

Regards,

Joel

Yes you can adjust bias 20-50mA per transistor,
Regards

 

[Tube Pro]

@ Ees,

do you have a clearer pics so we can clearly see resistors' colors and capacitors' orientation?
I use IC sockets for LM555 experiments, but not with the preamps (OP Amp) of my amps for more secured connection.

Good Luck,

Joel

 

[apexaudio]

+/-15V across zeners is most important voltage for function all circuit...

 

[apexaudio]

i took pics this morning
i used my fon to capture images
i guess its not that clear...

Can you zoom this area, I can't see clear, but I think you have mistake on your PCB.
Regards

 

[eesbiboi]

Can you zoom this area, I can't see clear, but I think you have mistake on your PCB.
Regards

im very very sorry for unclear pics...
i hope this would help...

 

[hadita]

It's true,

NSL 32: this device together with its related parts will prevent your amp from clipping or overdriven beyond its capability.
It decreases input impedance allowing small amount of signal going into the 1st stage OP Amp, when the circuit senses an over current / voltage at the output / speaker terminal.

@ Tube pros & maihalo, thanks to information but if it happens clips how to influence or power of damaged speakers

regard

 

[hadita]

@ Tubepro and maihalo, on the basis of the information, but if this happens the clip to the speakers or as a result of damage to the power

 

[Tube Pro]

CLipping

@ Tubepro and maihalo, on the basis of the information, but if this happens the clip to the speakers or as a result of damage to the power

Hi hadita,

you'll notice sound distortion when your amp is clipping or overdriven.
decreasing your sound level input or the volume control, will fix the problem.

Regards,

Joel

 

[apexaudio]

im very very sorry for unclear pics...
i hope this would help...

On your PCB emiter 2SA1837 is connect to colector 2SA1943... Your 2SA1837 is on wrong position, you must move it 2,5mm, and then emiter 2SA1837 will be connect to base 2SA1943,
Regards