Two questions I would like to ask here.
1. I purchased a headphone amp form a diy'er about a year ago and it has been great. I opened it up and it runs off two AD823AN's that are socket'ed. Can I upgrade these to OP-627's? This amp runs off of a single 9v. If I can not are there other options that would be a good upgrade to the AD823AN?
2. If I cannot do the swap above is there a basic headphone amp kit or what not that I can get my feet wet with that uses the OP-627 opamps? Are there any good crash course in basic signal amplication and opamps I can look at or buy?
Thanks
1. I purchased a headphone amp form a diy'er about a year ago and it has been great. I opened it up and it runs off two AD823AN's that are socket'ed. Can I upgrade these to OP-627's? This amp runs off of a single 9v. If I can not are there other options that would be a good upgrade to the AD823AN?
2. If I cannot do the swap above is there a basic headphone amp kit or what not that I can get my feet wet with that uses the OP-627 opamps? Are there any good crash course in basic signal amplication and opamps I can look at or buy?
Thanks
do nothing
AD823 is so much hi-fi op-amp - real top class Analog Devices amplifier -
it is almost impossible to upgrade
suppose you should try with OPA627 or OPA637
then the circuit would have been setup for AD823 use
and you may not be able to get better out of OPA627,
unless you design a new circuit to support your OPA627 chip
... probably you could only do only worse
upgrades
is when we CAN do better
otherwise will only be a downgrade, in some respect
Lineup - audo regards
AD823 is so much hi-fi op-amp - real top class Analog Devices amplifier -
it is almost impossible to upgrade
suppose you should try with OPA627 or OPA637
then the circuit would have been setup for AD823 use
and you may not be able to get better out of OPA627,
unless you design a new circuit to support your OPA627 chip
... probably you could only do only worse
upgrades
is when we CAN do better
otherwise will only be a downgrade, in some respect
Lineup - audo regards
Yes,
the audio elite makes preamp circuits/buffers with OPA627
If you search forum for OPA627
you will find a bunch of good schematics/applications for this top of the top Op-Amp.
Only drawback with OPA627 is the price .. not The Performance, for sure
Your amplifier was designed with AD823 in mind.
Think you do good let is stay that way = original.
Regards
What is it that you dislike about your headphone amplifier?
Its like: "Step 1: Identify the problem."
Crash course in amplifiers? Okay. http://myweb.tiscali.co.uk/nuukspot/decdun/ and http://headwize.com/projects/index.htm
Its like: "Step 1: Identify the problem."
Crash course in amplifiers? Okay. http://myweb.tiscali.co.uk/nuukspot/decdun/ and http://headwize.com/projects/index.htm
Thanks,
I have read through quite a few of these articles. I am having to look a lot of the terms up but some of it is quite informative. I don't dislike my amp but I would like to see how different opamps sound. It is sort of like saying I like coffee but there are different blends of coffee I like. The only particular flaw I can find is the amp gets a little harsh in the upper midrange at reasonable volumes using either my grados or senn 580s.
I have read through quite a few of these articles. I am having to look a lot of the terms up but some of it is quite informative. I don't dislike my amp but I would like to see how different opamps sound. It is sort of like saying I like coffee but there are different blends of coffee I like. The only particular flaw I can find is the amp gets a little harsh in the upper midrange at reasonable volumes using either my grados or senn 580s.
good question, espressogeek
i like to know how my opamp sounds
& how sounds different opamps
the keyword here is sound
opamps are quiet
they do not make sound .. not even transistors make sound we can hear
a well designed audio opamp & a good application of this opamp
will be 'transparant' in terms of influence on output
now, louspeakers make sounds .. no doubt
this is what they SHOULD DO, if no sound .. throw it in your garbage
same with headphones
they make sounds
with much less distortion, influence on sound quality, than Speakers
so you have MORE CHANCE to hear something of those previous stages in your sound system
if you listen in HeadPhones,
but!!! must be HeadPhones of very high quality
speakers usually have at least 10 times higher distortion
than good Phones (see Sennheiser )
Good Phones destroys the electrical signal like only 0.2%
this is the level of distortion of World's finest Phones
for example by http://www.sennheiser.com/
now, opamps
are advertised having 0.00003 % distortion
Even 0.001 % DISTORTION .. is one very tiny drop in the SEA of Sound distortion.
And with regards to music signal + opamp system
The only thing you would hear is music .. nothing else.
For one normally good opamp in one normal good audio circuit.
.. these are the facts
.. now, let's listen to all or some of The Myths .. of audio sounds
so post on people
& our golden, golden ears ... some poor boy may believe you
Lineup Audio LAB - Opamp designs for Hi-fi HeadPhones
Lineup
Lineup - not stupid enough to be looking for his one drop
put into the Atlantic Ocean Waves
i like to know how my opamp sounds
& how sounds different opamps
the keyword here is sound
opamps are quiet
they do not make sound .. not even transistors make sound we can hear
a well designed audio opamp & a good application of this opamp
will be 'transparant' in terms of influence on output
now, louspeakers make sounds .. no doubt
this is what they SHOULD DO, if no sound .. throw it in your garbage
same with headphones
they make sounds
with much less distortion, influence on sound quality, than Speakers
so you have MORE CHANCE to hear something of those previous stages in your sound system
if you listen in HeadPhones,
but!!! must be HeadPhones of very high quality
speakers usually have at least 10 times higher distortion
than good Phones (see Sennheiser )
Good Phones destroys the electrical signal like only 0.2%
this is the level of distortion of World's finest Phones
for example by http://www.sennheiser.com/
now, opamps
are advertised having 0.00003 % distortion
Even 0.001 % DISTORTION .. is one very tiny drop in the SEA of Sound distortion.
And with regards to music signal + opamp system
The only thing you would hear is music .. nothing else.
For one normally good opamp in one normal good audio circuit.
.. these are the facts
.. now, let's listen to all or some of The Myths .. of audio sounds
so post on people
& our golden, golden ears ... some poor boy may believe you
Lineup Audio LAB - Opamp designs for Hi-fi HeadPhones
Lineup
Lineup - not stupid enough to be looking for his one drop
put into the Atlantic Ocean Waves
I built a Cmoy based on the JDS board and when it was working (eh, see another thread about that, my own fault) it clobbered the sound of this little amp when listening to my HD-580s. I built it using an OPA2227. I was reading on Tangent's site about how little current the 823 op amps in the Mu can put out compared to other op amps and I believe that is part of the problem. I have several new op amps coming to use in building my own amps (working on a PPAv2 right now, should be finished very soon when the parts arrive monday) but I will try to replace these 823's with something more robust such as a 2227 or LM4562NA. In reviewing this amp I do have another question. Why would you run two dual channel op amps , one for left and another for right, when you could run just a single channel op amp in each side? I've tried googling for an answer but I can't seem to find an explanation.
Any ideas on the self buffered dual op amp approach? I have a bad feeling the design of the virtual ground might not support another set of dual op amps that draw/output more power since it is based on the tle2426 divider with two capacitors in parallel in front of it. This amp is also biased into class A, I imagine with a resistor, which will also increase current draw, no?
When you say "self buffered", do you mean with one half a dual feeling the other half of a dual, or having the two halves of a dual running in parallel? The second approach has some sort of merit....the first has perhaps a very small amount of merit in ensuring that the voltage amplification occurs cleanly, but in the end, the second half of the dual can't supply any more current than the first half could on it's own. In terms of power draw, I'd say it's not worth it.
Operating in parallel will allow more current to be supplied, which could be useful if you're using opamps with a low current capacity, however, in some cases it can make the opamp quite unhappy, making it unstable or causing it to get quite hot.
Biasing into class a will increase power draw, but, in the case of using low current opamps, will have the more serious effect of reducing the available current. If you've got an opamp which can supply 25 mA, and you bias it into class A by sinking, say, 10 mA, then you have in a very real sense now only got an opamp capable of supplying 15mA. If you were powering headphones with a low impedance, that would be a problem, but the senn's are nominally 300 ohms, so the opamps ought to be able to swing several volts even with only 15mA.
Operating in parallel will allow more current to be supplied, which could be useful if you're using opamps with a low current capacity, however, in some cases it can make the opamp quite unhappy, making it unstable or causing it to get quite hot.
Biasing into class a will increase power draw, but, in the case of using low current opamps, will have the more serious effect of reducing the available current. If you've got an opamp which can supply 25 mA, and you bias it into class A by sinking, say, 10 mA, then you have in a very real sense now only got an opamp capable of supplying 15mA. If you were powering headphones with a low impedance, that would be a problem, but the senn's are nominally 300 ohms, so the opamps ought to be able to swing several volts even with only 15mA.
Thank you for replying to my post. I am still learning this stuff and I expect I will be for a long time.
I believe I have an idea of what is going on with this design. The designer specifies that he implemented "Jung Multiloop Technology" on this amp. Since there are no buffers I imagine he has done this by using both sides of the op amp and buffering itself. Unfortunately, I do not know how to depict this but does this sound feasible? Are they any common schematics for a "JML" implementation using a single dual op amp? I suppose I would like to "unJung" it and work in a pair of single channel op amps. Perhaps there is some way to enhance the virtual ground design a bit by air wiring something to it and continue to use the JML dual self buffered op amps with a different op amp type installed.
I believe I have an idea of what is going on with this design. The designer specifies that he implemented "Jung Multiloop Technology" on this amp. Since there are no buffers I imagine he has done this by using both sides of the op amp and buffering itself. Unfortunately, I do not know how to depict this but does this sound feasible? Are they any common schematics for a "JML" implementation using a single dual op amp? I suppose I would like to "unJung" it and work in a pair of single channel op amps. Perhaps there is some way to enhance the virtual ground design a bit by air wiring something to it and continue to use the JML dual self buffered op amps with a different op amp type installed.
http://electronicdesign.com/Globals/PlanetEE/Content/1518.html is one of the original Jung Multiloop discussions, you might find it helpful. Also take a look at the schematic of the PPA, http://tangentsoft.net/audio/ppa/amp2/misc/schematic8.pdf
In more direct answer to your question: if you're clever about it, maybe you can.
http://cimarrontechnology.com/single-to-dualop-ampadapterpn020302.aspx
That adaptor will accept two single SMD opamps and convert the pinout to an ordinary dual opamp.
This version http://cimarrontechnology.com/single-to-dualop-ampadapter-dipversionpn021001.aspx will accept DIP parts if that makes you more comfortable, but you may struggle to find an appropriate buffer.
By populating the correct half (this, I imagine, would be the hard part) with, say, OPA627, as the amplifier, and the other half with, perhaps, LMH6321 (there's a little more work involved in this bit, the pinouts of a single opamp aren't quite identical to this buffer, just very close) you could have a properly buffered Jung Multiloop amplifier.
Problem is that the buffering opamp must have AT LEAST the same bandwidth as the amplifying opamp (and, of course, an equal or greater current capacity, or it rather defeats the point), but particularly fast opamps aren't terribly happy on that kind of adaptor.
http://cimarrontechnology.com/twopre-mountedopa627auop-ampson020302adapterpnopa627au-020302s.aspx
Since the OPA627 is rated for a reasonable current output of 45mA, you could use that adaptor, with two premounted 627's, with probably quite good results. Since it's probably among the cheapest ways to get two OPA627's, I'd recommend it even if you intended to remove one to use a different buffer.
In more direct answer to your question: if you're clever about it, maybe you can.
http://cimarrontechnology.com/single-to-dualop-ampadapterpn020302.aspx
That adaptor will accept two single SMD opamps and convert the pinout to an ordinary dual opamp.
This version http://cimarrontechnology.com/single-to-dualop-ampadapter-dipversionpn021001.aspx will accept DIP parts if that makes you more comfortable, but you may struggle to find an appropriate buffer.
By populating the correct half (this, I imagine, would be the hard part) with, say, OPA627, as the amplifier, and the other half with, perhaps, LMH6321 (there's a little more work involved in this bit, the pinouts of a single opamp aren't quite identical to this buffer, just very close) you could have a properly buffered Jung Multiloop amplifier.
Problem is that the buffering opamp must have AT LEAST the same bandwidth as the amplifying opamp (and, of course, an equal or greater current capacity, or it rather defeats the point), but particularly fast opamps aren't terribly happy on that kind of adaptor.
http://cimarrontechnology.com/twopre-mountedopa627auop-ampson020302adapterpnopa627au-020302s.aspx
Since the OPA627 is rated for a reasonable current output of 45mA, you could use that adaptor, with two premounted 627's, with probably quite good results. Since it's probably among the cheapest ways to get two OPA627's, I'd recommend it even if you intended to remove one to use a different buffer.
I don't by the wax thing. It sounded great in my little CMOY. I am going to review this a bit more. It doesn't sound to me like the use of JML in a dual op amp is really advantageous unless you are trying to gain the benefits of such a design with a low part count / foot print. At any rate, I'm just going to button this little amp up and give her a new home via Ebay or something.
I started working on my own amp on a rat shack board last night. I want to use a discrete buffer and a dual op amp. Then later on I'll add discrete output buffers. I think this will give me a good opportunity to gain more knowledge, understand basic electronic theory, and have a good time doing it. I think it is better to start fresh then try to tweak someone else's design when their board was not intended for doing so.
Thanks for everyone's feedback and I'm sure I will be "seeing" you in other threads.
Cheers
I am going to review this a bit more. It doesn't sound to me like the use of JML in a dual op amp is really advantageous unless you are trying to gain the benefits of such a design with a low part count / foot print. At any rate, I'm just going to button this little amp up and give her a new home via Ebay or something.I started working on my own amp on a rat shack board last night. I want to use a discrete buffer and a dual op amp. Then later on I'll add discrete output buffers. I think this will give me a good opportunity to gain more knowledge, understand basic electronic theory, and have a good time doing it. I think it is better to start fresh then try to tweak someone else's design when their board was not intended for doing so.
Thanks for everyone's feedback and I'm sure I will be "seeing" you in other threads.
Cheers
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.