Have you tried different dual op-amps, in the "1976 design"and see what ones please you. maybe this is sufficient & call it a day. I'd try TI OPA2904 or the LM4562.
I am lead to believe the only improvement in the new version was in the noise dept, (low value variable R's) similar as was done with the tone ckt for the Elektor 2012 pre-amp.
You tell me, does the "1976 design", sound any noisier than the "Elektor 2012 pre-amp tone control"? If it does, then try LM4562 in the "1976 design" and try again?
Steam Age
Hi,
I am afraid you are ahead of your time with the suggestions. The 1976 design used discrete transistors everywhere in the line and tone control circuitry. In fact it was criticised for doing so but the critic copped out of showing an IC version... ICs were probably not upto the task back then.
I have listened to the 1976 design for about 4 hours today. It is not quite so wide and open as the Pass B1, but there is certainly more bass (possibly too much, but there are tone controls). I think it is also slightly more muddled at high levels... but given that I have not even cleaned the contacts, it is not bad.
Hi,
I am afraid you are ahead of your time with the suggestions. The 1976 design used discrete transistors everywhere in the line and tone control circuitry. In fact it was criticised for doing so but the critic copped out of showing an IC version... ICs were probably not upto the task back then.
I have listened to the 1976 design for about 4 hours today. It is not quite so wide and open as the Pass B1, but there is certainly more bass (possibly too much, but there are tone controls). I think it is also slightly more muddled at high levels... but given that I have not even cleaned the contacts, it is not bad.
A New Thread
A new thread for old codgers? I don't think it would attract the crowds exactly. I have just realised that apart from my music sources (NAS via QNAP into Logitech Squeezebox and external DAC) my preamp (Self design) is from 1976, so are my speakers (JBL 4343) but my Pass Aleph 5 is (relatively) new at 1991! I, on the other hand, am from 1944 .. all very depressing.
No, but the 96 precision preamp is viewable on Google Books, chapter 11.
Small- Signal Audio Design - Douglas Self - Google Books
76 Self Design
I have the Wireless World magazine which contained all the information and build instructions for teh design.
I can email them if you want
George
I have the Wireless World magazine which contained all the information and build instructions for teh design.
I can email them if you want
George
Hitachi 2sa1083-1084 are just lower voltage versions 60,90V which are fine for this application, if you can get any. NEC, Toshiba, Rohm all made low Rbb devices, but sadly most are only available as NOS.
KSA992 from Mouser is cheap and available, prob. it has more noise but is probably better than a 2n4403. Not sure if Low Noise: BC559, BC560 are any better. These are all cheap alternatives, so you have lots of choices.
KSA992 from Mouser is cheap and available, prob. it has more noise but is probably better than a 2n4403. Not sure if Low Noise: BC559, BC560 are any better. These are all cheap alternatives, so you have lots of choices.
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Hello everyone,
It's my first post on this forum, so please forgive me for being a bit off-topic or simply wrong. I'm quite new to diy audio, however I did both my Bachelor and Master thesis (a couple of years ago) in an Electroacoustics division of my faculty at the Technical University of Warsaw, Poland. I took some good electroacoustics courses back then, however I have to admit I forgot a lot of what I learnt then and only now I try to enter audio field again (I'm not even sure this expression is a valid english expression
)
Anyway, back to the point. I've been reading this great thread for a week now and I still haven't finished, still have a few pages to read, so my post is probably not related to the recent replies. What I want to say though is, that I've particularly liked all the comments regarding sound of op-amps or different circuit topologies very much. And I have a lot of thoughts on the matter, I just don't find it easy to express them in english.
Ok, I'll try. Back at my university there was this guy, electroacoustics guru, who could by no means be called a subjectivist. He's had some opinions I'd never heard anywhere else, yet he always tried to back his theories up with measurements or good math/physics explanation. There's this one theory I remember very well. He used to say that an air as a medium of wave propagation is by no means a transparent one. And I think we can all agree to that, it's not some subjectivists' bs. What we CAN argue about is whether an amount of air between the speaker and the listener affects the sound in an audible way.
So, the air can be (after transferring its characteristics to electrical equivalents) modeled as a poor RLC filter or rather as a distributed net of poor and nonlinear RLC filters, than as a connection of lumped components. And these components are nonlinear i.e. capacitances, inductances and resistances change with the amplitude, frequency of the signal. They also change with temperature and even with humidity of the air. Of course we can argue over these nonlinearities being above a hearing threshold or not (I'm not talking about unquestionably audible effects of the listening room like early reflections, reverberations or amplitude change, I'm talking about nonlinearites of an air as a medium).
What I'm getting at is that this guy claims that if the audio system we play our music on (and the recording chain that was used to produce the music as well) has a characteristic similar in its nonlinearities to the one of air, then suddenly the whole music starts to... you know, shine. Speakers disappear, the space appears and everything seems natural. The reason is obvious - adding a few metres of 'air' (an audio chain used to record and reproduce the sound) simply is transparent to our perception, even if it's nonlinear. Our brains are trained to ignore that or to simply perceive such sound as coming not from a speaker but from a real source standing in our room. I guess a good analogy to that is how we try to fool our brains with 3D television. Binaural recordings are also a good example of how we try to create a convincing illusion.
So, it is transparent to our perception BECAUSE it is nonlinear but in a very specific way.
What does it have to do with the sound of op-amps? Well (but please, bear in mind, it's just my opinion, I'm not saying it is an unquestionable truth, because it would be very hard to prove it if not impossible) changing an op-amp, or the volume, or exchanging one circuit topology with another may suddenly result in a sound reproduction system that's exactly like just a few extra meters of air. And maybe that's one of the reasons (apart from personal preferences) for which different people have so different opinions on the same op-amps - 'cause op-amps are only a small portion of the whole audio chain.
To make things more complicated - listening to 2 different op-amps (or, to be accurate, to the same chain with only op-amps replaced) on 2 different days and claiming it's their sound that's changed the whole perception so much is a big over-statement, IMHO. The humidity may have changed, the temperature of the room (even though this is rather constant in relation to humidity I guess) and, what's more important, the listener's MOOD may have changed. Very often I find myself standing in front of my CD collection, not knowing what to choose, 'cause nothing suits my mood at a time. There are these days when I prefer Radiohead with their heavily computer-modified sounds to other bands, but there are also days when all I can listen to are some mellow cool jazz records from the sixties. So, hard beats with lost of heavy industrial bass is what pleases me on one day, and only gentle piano chords on others. And that's how I've learnt not to trust my perception that much when it comes to such subtle things like op-amps or, what's even more subtle, cables sound.
Having said that, I do believe that op-amps indeed have their intrinsic audible characteristics, even though THD measurements may not reveal them, yet there also so many other factors affecting the sound that we have to take heed of, that all these precise descriptions regarding op-amps sound can't be treated seriously.
I hope I've just provoked some of you to discussion. There's nothing worse that writing a looong post and see it's not commented by anyone
It's my first post on this forum, so please forgive me for being a bit off-topic or simply wrong. I'm quite new to diy audio, however I did both my Bachelor and Master thesis (a couple of years ago) in an Electroacoustics division of my faculty at the Technical University of Warsaw, Poland. I took some good electroacoustics courses back then, however I have to admit I forgot a lot of what I learnt then and only now I try to enter audio field again (I'm not even sure this expression is a valid english expression
)Anyway, back to the point. I've been reading this great thread for a week now and I still haven't finished, still have a few pages to read, so my post is probably not related to the recent replies. What I want to say though is, that I've particularly liked all the comments regarding sound of op-amps or different circuit topologies very much. And I have a lot of thoughts on the matter, I just don't find it easy to express them in english.
Ok, I'll try. Back at my university there was this guy, electroacoustics guru, who could by no means be called a subjectivist. He's had some opinions I'd never heard anywhere else, yet he always tried to back his theories up with measurements or good math/physics explanation. There's this one theory I remember very well. He used to say that an air as a medium of wave propagation is by no means a transparent one. And I think we can all agree to that, it's not some subjectivists' bs. What we CAN argue about is whether an amount of air between the speaker and the listener affects the sound in an audible way.
So, the air can be (after transferring its characteristics to electrical equivalents) modeled as a poor RLC filter or rather as a distributed net of poor and nonlinear RLC filters, than as a connection of lumped components. And these components are nonlinear i.e. capacitances, inductances and resistances change with the amplitude, frequency of the signal. They also change with temperature and even with humidity of the air. Of course we can argue over these nonlinearities being above a hearing threshold or not (I'm not talking about unquestionably audible effects of the listening room like early reflections, reverberations or amplitude change, I'm talking about nonlinearites of an air as a medium).
What I'm getting at is that this guy claims that if the audio system we play our music on (and the recording chain that was used to produce the music as well) has a characteristic similar in its nonlinearities to the one of air, then suddenly the whole music starts to... you know, shine. Speakers disappear, the space appears and everything seems natural. The reason is obvious - adding a few metres of 'air' (an audio chain used to record and reproduce the sound) simply is transparent to our perception, even if it's nonlinear. Our brains are trained to ignore that or to simply perceive such sound as coming not from a speaker but from a real source standing in our room. I guess a good analogy to that is how we try to fool our brains with 3D television. Binaural recordings are also a good example of how we try to create a convincing illusion.
So, it is transparent to our perception BECAUSE it is nonlinear but in a very specific way.
What does it have to do with the sound of op-amps? Well (but please, bear in mind, it's just my opinion, I'm not saying it is an unquestionable truth, because it would be very hard to prove it if not impossible) changing an op-amp, or the volume, or exchanging one circuit topology with another may suddenly result in a sound reproduction system that's exactly like just a few extra meters of air. And maybe that's one of the reasons (apart from personal preferences) for which different people have so different opinions on the same op-amps - 'cause op-amps are only a small portion of the whole audio chain.
To make things more complicated - listening to 2 different op-amps (or, to be accurate, to the same chain with only op-amps replaced) on 2 different days and claiming it's their sound that's changed the whole perception so much is a big over-statement, IMHO. The humidity may have changed, the temperature of the room (even though this is rather constant in relation to humidity I guess) and, what's more important, the listener's MOOD may have changed. Very often I find myself standing in front of my CD collection, not knowing what to choose, 'cause nothing suits my mood at a time. There are these days when I prefer Radiohead with their heavily computer-modified sounds to other bands, but there are also days when all I can listen to are some mellow cool jazz records from the sixties. So, hard beats with lost of heavy industrial bass is what pleases me on one day, and only gentle piano chords on others. And that's how I've learnt not to trust my perception that much when it comes to such subtle things like op-amps or, what's even more subtle, cables sound.
Having said that, I do believe that op-amps indeed have their intrinsic audible characteristics, even though THD measurements may not reveal them, yet there also so many other factors affecting the sound that we have to take heed of, that all these precise descriptions regarding op-amps sound can't be treated seriously.
I hope I've just provoked some of you to discussion. There's nothing worse that writing a looong post and see it's not commented by anyone