Hi, here's my 2 cents worth,
I built 2 headphone amps to play around with opamps. One was a basic CMOY and the other a kit with output BJTs after the opamp. I tried a selection of 5 or 6 opamps.
In the CMOY different opamps made a big difference, as well, some opamps worked better with higher voltages. In the other headamp, I couldn't detect any difference. So I concluded that the selection of the right opamp is dependant on circuit design and implementation. You really need to try it for yourself.
In this case, we are all right IMHO.
regards
I built 2 headphone amps to play around with opamps. One was a basic CMOY and the other a kit with output BJTs after the opamp. I tried a selection of 5 or 6 opamps.
In the CMOY different opamps made a big difference, as well, some opamps worked better with higher voltages. In the other headamp, I couldn't detect any difference. So I concluded that the selection of the right opamp is dependant on circuit design and implementation. You really need to try it for yourself.
In this case, we are all right IMHO.
regards
salas said:
National.
Here's one of my prefered op-amps: the AD847 (left).
Simple circuit too.
On the right, you can see the 'simplified schematic' of the LM833, taken from National's datasheet.
Curious, isn't it?
It's more complex than yours.
This proves that those 'simplified' schematics don't tell half of the story.
Attachments
There is a huge difference in concept between developing an optimum sonicwise circuit from scratch, taking measures to pay layout, bypass, and psu justice, to components under evaluation, vs to just tweak simply a ready made machine.
Yes, many are ready to go to lengths and thats noble. Make mini PCBs, add supplies etc, etc.
But it happens to be just nice when a humble IC fits by accident (maybe) and sings. That LM schematic wasn't far more complex if you count the Isources shown vs drawn. And nobody said its the simplest, just simple.
And nobody said 833 is the sure workhorse, just said it happens to work sometimes. Plain words, for plain tweaks.
Yes, many are ready to go to lengths and thats noble. Make mini PCBs, add supplies etc, etc.
But it happens to be just nice when a humble IC fits by accident (maybe) and sings. That LM schematic wasn't far more complex if you count the Isources shown vs drawn. And nobody said its the simplest, just simple.
And nobody said 833 is the sure workhorse, just said it happens to work sometimes. Plain words, for plain tweaks.
Russ White said:Carlos, your attributing ideas to "us" which I don't think anyone has promoted. I don't think anyone proposed "just" swaping opamps.
This is what you recommended, and I've seen others doing the same:
Russ White said:If you are inclined then try the LM833, RC4560,OPA2227,AD8620, and whatever else you can find. Just use a DIP socket and try whatever you can find, it will be a lot of fun.
----
Russ White said:
No, I don't think so.
There's work to do first.
And depending on the circuit, you must judge if it's better to use a bipolar or a jfet input op-amp, but that's another story.
Yeah right, they all have 8 legs.
salas said:
You don't necessarily have to do so, although in some cases it's much better.
I've managed to put the OPA2132 on the Arcam 7SE, and sounding very good without having to make a new board for the analog stage. It sounded very bad at first, as expected with that miserable layout.
Btw as a side note, manufacturers insist on using a dual op-amp per channel for I/V and buffereing on CDPs.
That is, you have one dual op-amp for both duties, and you can't separate it.
That's totally unappropriate, as a good op-amp for buffering/low pass filter may not be as good for I/V.
It would be much better to use a dual op-amp for I/V (both channels), and another for the output buffer/filter.
In I/V you need high slew rate.
Not to say single op-amps everywhere, but that you only see on expensive gear.
Russ White said:Carlos where did I say to "only" swap the opamps.
You did say that, read again.
Can you be more polite, please?
You have some education problem.
Can we discuss in a civilized way?
I try to ignore you, but it's hard, when you came to this thread just to mention my name.
Ignore me too, it's good for your business.
And grow up.
My LM833 just oscillated when used with a complex notch circuit having positive and negative feedback. It was in stereo and both channels oscillated and not with the other op-amps used. It is not a bad decoupling affair because when used in a Sallen and Key filter, which is too a combination of positive and negative feedback, using exactly the same decoupling (I am very keen on decoupling and grounding schemes), it worked Ok.
~~~~~ Forr
§§§
~~~~~ Forr
§§§
Carlos, I saw your pre circuit, I remember some circuits in the old French Audiophile magazine with this 2SK170, from where I stuck and built various little circuits like yours around this jfet. And I use such SE gain stages built around 2SK170 with passive RIAA in between for my phono-stage NTE132 is another good option, especially for phono-stages. BTW such a phono-stage if constructed with care could outperform many (perhaps even most) super priced consumer ph.stages.
Have you tried it?
Salas:
I found you!)
Regards,
Thalis
------------------------------------------------------------------------------
I don’t like OPamps and GC, except for instruments gear
NTE132 is another good option, especially for phono-stages. BTW such a phono-stage if constructed with care could outperform many (perhaps even most) super priced consumer ph.stages. Have you tried it?
Salas:
I found you!
)Regards,
Thalis
------------------------------------------------------------------------------
I don’t like OPamps and GC, except for instruments gear
thalis said:Carlos, I saw your pre circuit, I remember some circuits in the old French Audiophile magazine with this 2SK170, from where I stuck and built various little circuits like yours around this jfet. And I use such SE gain stages built around 2SK170 with passive RIAA in between for my phono-stage
Have you tried it?
No, I didn't try it on a phono stage.
My phono pre is build around OPA637s biased to class-A, feeded from 3 series 12V SLA batteries (36V), with a BUF634 as a rail splitter.
Carlos, I am not upset with you. Why are you angry? I did not say to "only" change opamps to get the best performance out of them. What I said was that for his circuit, and his layout that in order to try multiple opamps to see the effect he only had to "just" use a dip socket. I think you are the one who needs a good dose of beer!
Cheers!
Russ
Why are you angry? I did not say to "only" change opamps to get the best performance out of them. What I said was that for his circuit, and his layout that in order to try multiple opamps to see the effect he only had to "just" use a dip socket. I think you are the one who needs a good dose of beer! Cheers!
Russ
Wow!!! Step out of the forum for one night....
CarlosFM and RussWhite, thank you both from the bottom of my heart.
I only needed to know if the circuit will work with a LM833. As funding (and time) became more available, better opamps would be tried.
My knowledge of electronics and opamps aren't to the level that I can choose an opamp because of input/output stages but I realise that changing opamps wont be just that.
Even if it means just changing resistor values, mods my be nesicary (spelling?).
The LM833 will be the prototype, mainly because the only other ones I've got is 741
CarlosFM and RussWhite, thank you both from the bottom of my heart.
I only needed to know if the circuit will work with a LM833. As funding (and time) became more available, better opamps would be tried.
My knowledge of electronics and opamps aren't to the level that I can choose an opamp because of input/output stages but I realise that changing opamps wont be just that.
Even if it means just changing resistor values, mods my be nesicary (spelling?).
The LM833 will be the prototype, mainly because the only other ones I've got is 741
Sure you are right but when you state this you don't know the goal really. Some think SACD is not particulary good and some others think MP3 at 64kb is perfectly fine. So if the thread starter is after something alright I'll guess a LM833 will do but hardly if he is after "spitzenklasse".carlosfm said:
About spelling: Check this serviceWynand said:
http://www.websters-online-dictionary.org/definition/necessary+ 
Lets get 2 the schematic
Right here it is....
C1 and R1 forms the DC block and HP Filter set to about 3hz
(I've changed C1 to 1uF)
C2..5 is for bypass and filtering
R3 is to help oscillation problems according to Mr Elliot (ESP).
Question:
1. Will this circuit work
2. Are my calculations OK
3. The DC offset of the LM833 is 0.3mV times the gain of the amp (20-30). This is approx 10mV. Is this ok?
4. I've been told that R3 and R5 can be omitted if the circuit is used as is. Is this true or should I leave them in?
Finally, Thanks to Per-Anders for the spel check.
Any comments, improvements or corrections are appreciated and requested.
Right here it is....
C1 and R1 forms the DC block and HP Filter set to about 3hz
(I've changed C1 to 1uF)
C2..5 is for bypass and filtering
R3 is to help oscillation problems according to Mr Elliot (ESP).
Question:
1. Will this circuit work
2. Are my calculations OK
3. The DC offset of the LM833 is 0.3mV times the gain of the amp (20-30). This is approx 10mV. Is this ok?
4. I've been told that R3 and R5 can be omitted if the circuit is used as is. Is this true or should I leave them in?
Finally, Thanks to Per-Anders for the spel check.
Any comments, improvements or corrections are appreciated and requested.
Attachments
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.