nel progetto di elektor del PA300 tra il piedino 5 ed 8 di IC1 viene collegato un condensatore da 33p denominato C9. qualcuno mi sa dire il motivo di questa scelta circuitale? vorrei realizzare il progetto sostituendo NE5534 con un OPA627 oppure con un OPA604 in quanto per le mie orecchie NE5534 è troppo freddo in termini di resa sonora. un grazie in anticipo a chi risponderà a questa mia domanda. ciao allego il circuito elettrico
in the draft elektor of PA300 between the leg 5 and 8 of IC1 it is connected to a capacitor 33p called C9. someone can tell me why this circuit choice? I would like to implement the project by replacing NE5534 with OPA627 or with a OPA604 as for my NE5534 ears is too cold in terms of sound. thanks in advance to those who will respond to my question. Hello Enclose the electrical circuit
in the draft elektor of PA300 between the leg 5 and 8 of IC1 it is connected to a capacitor 33p called C9. someone can tell me why this circuit choice? I would like to implement the project by replacing NE5534 with OPA627 or with a OPA604 as for my NE5534 ears is too cold in terms of sound. thanks in advance to those who will respond to my question. Hello Enclose the electrical circuit
Attachments
The 5534 is not unity gain stable, therefore a pin for frequency compensation is provided. the OPA604 is unity stable and doesen`t neet this cap. The OPA627 is different again. It maybe possible that this cap is not only responsible for the compensation of the opamp but also for the compensation of the whole amp too. difficult to tell from the schematic.
Anyway, I think easiest would be to try a OPA604 as it is unproblematic, the OPA627 is very fast so more critical to compensation and stability.
Salve, Jürgen
Anyway, I think easiest would be to try a OPA604 as it is unproblematic, the OPA627 is very fast so more critical to compensation and stability.
Salve, Jürgen
You can simulate the circuit using simulators such as LTspice and TINA-TI. Both are free. LTspice is from Linear Technology. TINA-TI is from Texas Instruments (TI).
Tom
Tom
I built a lot of these amps. If you use 5534 then you need to have a 33pf cap between pin 6 and 2 otherwise it will oscillate and do weird stuff when clipping. I have never tried the opa604
After seeing your attached thumbnail that weird behavior is caused by the protection circuits T4 and T5 activating
Thanks Bruce.
The capacitor is placed. That waveform is no load, with load the effect is the same, nothing changes by disconnecting the transistors from the VI limiter.
The capacitor is placed. That waveform is no load, with load the effect is the same, nothing changes by disconnecting the transistors from the VI limiter.
@xavirom: Didn't the answers you've yet been given on the same question in PA300 ELEKTOR, clipping problem. satisfy you enough?
Best regards!
Best regards!
Hi Kay Pirinha. No, the only response there was, does not apply in this case.
Thanks for the question.
Thanks for the question.
PA_300/400
Hello everyone.
This several months that we walk in the threads of discussions. To see and understand.
We work for a French humanitarian work. Emmaus.
I mainly deal with recycling. So we have access to a hellish amount of material.
Just for the introduction.
We have been repairing all equipment for over 20 years.
I do not claim to know everything, far from it. But we are a whole team to tinker and build a whole bunch of things.
In short, we have fun.
Elektor circuits have been updated for some time.
Normal, Elektor in France is quite a poem.
As we can no longer get out with once again, confinement.
We decided to make a sound system in the village.
The PA.300 Elektor is still buildable, parts available. So we started. We re-route the circuit board.
PA.300_400-600
For the 600, we started from the Elrad magazine, but the circuit was so equivalent to that of Elektor we directly modified the PA.300. PA.600 = 8 pairs. We have therefore modified the circuit ion feed resistances. We draw everything on Autocad, sorry. But Kikad and c ° it takes a bit of our head.
Okay, I'm attaching some of our work to give an idea.
See you everyone.
Jacky
Hello everyone.
This several months that we walk in the threads of discussions. To see and understand.
We work for a French humanitarian work. Emmaus.
I mainly deal with recycling. So we have access to a hellish amount of material.
Just for the introduction.
We have been repairing all equipment for over 20 years.
I do not claim to know everything, far from it. But we are a whole team to tinker and build a whole bunch of things.
In short, we have fun.
Elektor circuits have been updated for some time.
Normal, Elektor in France is quite a poem.
As we can no longer get out with once again, confinement.
We decided to make a sound system in the village.
The PA.300 Elektor is still buildable, parts available. So we started. We re-route the circuit board.
PA.300_400-600
For the 600, we started from the Elrad magazine, but the circuit was so equivalent to that of Elektor we directly modified the PA.300. PA.600 = 8 pairs. We have therefore modified the circuit ion feed resistances. We draw everything on Autocad, sorry. But Kikad and c ° it takes a bit of our head.
Okay, I'm attaching some of our work to give an idea.
See you everyone.
Jacky
Attachments
Beautiful! Mind to share your PCB layouts? And where do you plan to source these panel meters from?
Best regards!
Best regards!
I accidentally? just bought an Elektor PA300 unseen... I really want to know if it has ballansed inputs🙂 If not I would be gratefull if someone has links to a good kit for adding ballanced input.
Cheers!
Cheers!
Last edited:
The PA 300 has got a NE5534 as the input amplifier. Perhaps it is possible to add a NE5532 and arrange an instrumentation amplifier?
Best regards!
Best regards!
The Elektor PA 300 amplifier, as it was published originally, neither has a balanced input nor a balanced output.
Best regards!
Best regards!
1) Elektor PA300 does NOT have balanced input (attaching schematic below)
Good news is you do not need one 🙂
2) DBX 234 XL does have unbalanced outputs built-in, hidden in plain sight 😎
It has "electronically balanced" outputs, actually two conventional unbalanced outputs, each referred to ground, only fed exact same signal level but out of phase, each connected to pins 2 or 3 of XLR output.
You can use them individually as what they are, unbalanced outs.
Make an adapter cable: one end connected to male XLR pins 2 (signal) and 1 (ground/shield), at the other end male RCA (or 1/4" plug if amp was built for PA use and has an 1/4" jack instead).
Presto, your problem is solved.
Clearly suggested in DBX user manual, by the way:
As you see, both input and output can be used balanced/unbalanced.
