Hi to everyone!
I have been listening a lot more using headphones lately and I want to improve the sound of my system. I have a Cambridge Audio Azur 840E preamp with headphones output and that's what I use. I looked at the circuit and looks like an op amp based with a small power section.
I replaced the NE5532P with an OPA2134 I had laying around and I think I can hear improvements. What do you think of the circuit and the implementation? Would it be better to buy or build a dedicated external headphone amp?
Thanks!
I have been listening a lot more using headphones lately and I want to improve the sound of my system. I have a Cambridge Audio Azur 840E preamp with headphones output and that's what I use. I looked at the circuit and looks like an op amp based with a small power section.
I replaced the NE5532P with an OPA2134 I had laying around and I think I can hear improvements. What do you think of the circuit and the implementation? Would it be better to buy or build a dedicated external headphone amp?
Thanks!
"MYTH: MOST OP AMPS SOUND DIFFERENT - There’s a general perception that op amps sound different. Many gear manufactures tout op amp brands and part numbers in their marketing literature. The $3 OPA2134 is supposed to sound much better than the $1 NE5532 and the $10 AD8610 is supposed to sound better still. But do they?.... "
https://nwavguy.blogspot.com/2011/08/op-amps-myths-facts.html
In short , NE5532 was the best choice made by the designers
I would choose OPA2134 over 5532 , if I wanted to make high gain guitar or mic preamp
https://nwavguy.blogspot.com/2011/08/op-amps-myths-facts.html
In short , NE5532 was the best choice made by the designers
I would choose OPA2134 over 5532 , if I wanted to make high gain guitar or mic preamp
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Some do... I guarantee you that you can hear a difference between a uA741 and an OPA1611 for example. 🙂 But point well taken.
I'd be careful with random opamp substitutions in that circuit. With the added output stage you can get yourself into stability trouble if the opamp's UGBW approaches that of the output stage. That said, the BC337/327 devices should be pretty fast emitter followers so you're not likely to have instability, but it's definitely something I'd keep an eye out for.
Tom
I'd be careful with random opamp substitutions in that circuit. With the added output stage you can get yourself into stability trouble if the opamp's UGBW approaches that of the output stage. That said, the BC337/327 devices should be pretty fast emitter followers so you're not likely to have instability, but it's definitely something I'd keep an eye out for.
Tom
Why is the input so heavily loaded with 3.9k? Maybe the electrolytic could be replaced or at least augmented with a polypropylene cap?
The circuit is specifically designed around the '5532. The input bias current is not-small. There is a switch and a cap. With a large resistor, when you throw the switch, in sensitive headphones, the "POP" will scare you, or at least "sound cheap".
The 3.9k is balanced by 22k||4.7k at the other input.
I would not go much higher than 4.7k without checking noise voltage. I think the '5532 could benefit from even lower NFB impedance, but this far up in the gain-structure, that may be moot.
With a few minor details, this is just about what I designed for myself for my recording work.
It is super conventional - e.g. Douglas Self published it (with three pairs at the output) in his Small Signal Audio Design.
What is the quiescent current of the output transistors? BC327/337 are good for 600mW, so, if the current is less than, say, 5mA each, you could try to (carefully!) increase it by increasing R396.
I’m using my Sony XBA-4 which are 8 ohm earphones. Do you consider this headphone amp enough for them?
It may deliver 2,500 mW in 8r. The XBA-4 are rated 100mW. At 100 mW they put 128dB SPL in your ear.
This amp is way more than "enough".
NE5532 can be replace by OPA1678 for better spec. Maybe 0.0001% better for low gain.
Other op amp use at your own risk. Example RC4558, NJM4556 will sound worse than NE5532.
Other op amp use at your own risk. Example RC4558, NJM4556 will sound worse than NE5532.
Thanks for your answers!
What's the worst it can happen using the OPA2134? I checked with the scope and there is no oscillation and it's temperature is normal. Is it just that the NE5532 wold work better or am I risking something here?
What's the worst it can happen using the OPA2134? I checked with the scope and there is no oscillation and it's temperature is normal. Is it just that the NE5532 wold work better or am I risking something here?
There are sockets for the opamps?
What is the source of the schematics? And are you sure they're correct?
What is the source of the schematics? And are you sure they're correct?
I installed sockets for the op amps. The schematics are from hifiengine and as far I can tan tell, are correct.
In a later edition of that book he also 'raves' about the LM4562, basically suggesting to forget the 5532....
How about the 5532 offset in a DC circuit. You might hear thunks in the phones. Maybe the 17v supply is close to the limit where 15v should be enough.
https://www.diyaudio.com/community/...-worth-it-an-external-one.396405/post-7282505
Yes, almost nobody needs +/-17V. My professional dreadnot hotboxes were closer to +/-11V output and I never clipped them even in the room recording a brass ensemble.