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Elektor-Giant 1000W

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And here the security schematic.
 

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Ok something new:

I have powered up the caps in the psu.
C22,C23 each 440µF/100V
C19,C26 each 4700µF/25V
C20,C21 each 220µF/16V

4 little caps 4,7pF like in the schematic from the AF-3.

Nothing helps against my nasty noise in the power-off sequence.
So i take this caps out of my design.

It's a funny amp from elektor.
You can put in and take out elements and it wouldn't be better or worse :)

Don't know what else i can/should do.
 
Am I the only one who thinks the transformers look a little small for a 1000W amp?

I wonder if it might not be a good idea to connect the caps for the 90V supply from the 90V rail to ground, rather than to the 12V rails. But since there's a definite need for a beefier transformer, why not get a 60-0-60 transformer and skip the stacked power supplies?

EDIT: I just realized that those supplies only feed the driver circuitry. I suppose there's a hefty toroid underneath?
Still, I'd change the supplies to stack the secondaries of the transformers directly, and then rectify and filter the individual voltages separately.
 
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buzz

anch'io avevo gli stessi problemi! ronzio e ritardo sul relay.
gli ho risolti cambiando la protezione con quella fornita assieme al crescendo.
il ronzio e svanito completamente applicando alle due alimentazioni le regole dettate dalla National per l'alimentazione da applicare al finale composto con LME49830.
tutti i difetti sono spariti e come ho gia detto il suono e diventato superbo.
un'altra cosa voglio dire gli stessi difetti erano presenti nel crescendo ed allora gli avevo eliminati stabilizzando a transistor l'alimentazione.
spero di essere stato utile
saluti
Guido
too had the same problems! buzz and delay on the relay.
I solved by changing the protection that came with your growing.
the buzz and vanished completely by applying the two supplies the rules dictated by the National for the power to be applied to the final compound with LME49830.
all the faults have disappeared and as I said the sound and become proud.
another thing I want to say the same defects were present in the growing and then I had eliminated by stabilizing the power transistor.
I hope I was helpful
regards
Guido
 
i hope it is ok to join this thread.. :) this design is asking for 90volts at the input for the driver stage, I have 80volts from my transformer after recitifying and secondary line at 70volts for powerstage. I have problems to reconfigure the values of the zener, maybe zener D1 and D3, and maybe some resistors at the psu, anybody has a quick solution. ?
best regards Niklas.
 
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elektor

ciao
lo ho realizzato con le specifiche di elektor.
90V sul'ingresso del 7808 e del 7908 ed anche i 72V richiesti secondari.
come diodi per formare gli 80V ho usato quelli che avevo cioè uno oppure due diodi che mi fornissero i 72 V richiesti, per il resto non ho modificato nulla.
lo ho usato per anni con molta soddisfazione, ora ho preso i 2SK135/2SJ50 e li ho pilotati con LME49830, praticamente ho realizzato lo schema della texas.
ora però devo affermare che non ne valeva la pena in quanto il suono e uguale all'ampli di elektor, ciò che rende quell'amplificatore straordinario sono i mosfet Hithaci.
voglio ricordare che senza adottare lo schema parziale dell'alimentazione della texas si nota un ronzio che non si toglie nemmeno con elettrolitici di ottima qualità, quindi lo devi adottare per forza, ripeto come ho già detto che nel crescendo avevo risolto tutti i suoi problemi stabilizzando a transistor l'alimentazione, usavo la coppia TIP142/147.
ripeto per gli 80V puoi usare qualunque conbinazione di zenner purchè la somma fornisca 72 V per il resto attieniti alle specifiche di elektor.
il sax sembra palpabile la voce è naturale e la dinamica, l'incisività che ti da alle frequenze basse e fantastica.
se posso esserti di aiuto non esistare a contattarmi.
Guido
Hello
I carried it with specific elektor.
90V sul'ingresso of 7808 and 7908 and also the required 72V secondary.
such as diodes to form 80V I used the ones I had that one or two diodes that would provide me the required 72 V, for the rest I have not changed anything.
I have used it for years with great satisfaction, now I have taken the 2SK135 / 2SJ50 and I have driven them LME49830, I have basically realized the scheme of texas.
But now I have to say that it was not worth it because the sound is equal to the amp of elektor, what makes it extraordinary that amplifier are the mosfet Hithaci.
I want to remember that without adopting the power of texas chart partition you notice a humming sound that would not take off with high quality electrolytic, so you have to take by force, I repeat as I have already said that in growing up I had solved all his problems by stabilizing transistor power, I used the TIP142 / 147 torque.
I repeat for 80V you can use any combination under Zenner provided the sum provides 72 V for the rest just follow the specifications of elektor.
sax seems palpable voice is natural and dynamic, the incisiveness that gives you at low frequencies and fantastic.
if I can help do not hesitate to contact me.
Gu
ido
 
What is the sound at switch off, high pitched or a low thump? I'd connect it to a dummy load and scope the output, then do the same with speakers attached to see what's happening. It sounds like the amp is oscillating at SW off.


One thing to note, doubling up the capacitance in the PSU is in general not a good idea, it stresses the main tfmr, you have a lot more surge current, some heavy duty thermistors on the AC IP would help as would a slow start circuit.




Andy.
 
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