Yes, my comments were about power amps (Class AB/B). Class A power amps, provided they always operate in A are not so demanding.
Where is the need for a capacitance multiplier in a low currrent circuit? Low currents (many opamaps do not work in Class A) don't need large and bulky capacitors surely?
Yes i see My main goal is to arrive at 2Vrms clean i.e. with very low THD+noise
First things first
Reached that goal i could start with power amps
I think that opamps should be the answer As someone has already advised me is very very difficult to get the same performance of opamps with discrete circuits A good evidence could be to look what they use at Audio Precision to amplify the signal of their analog generators
Difficult to find something cleaner My guess is that they use opamps ?
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yes those One thing i am noticing It is not possible to get very low THD+noise from discretes without using very complex circuitations
Much easier with opamps And i have also another big curiosity To see what premium brands use to amplify the signals of their top of the line signal generators I have seen the 1kHz sine distortion spectrum of the analog generator inside an Audio Precision apx555 I am amazed I am attaching it
I think i see absolute perfection
However here there are some informations
https://archimago.blogspot.com/2020/07/pictures-audio-precision-apx555-b.html
i love the smd look ... unfortunately is almost impossibile to use smd with expensive tools But they look gorgeous And the most recent parts have also great specs ...
Much easier with opamps And i have also another big curiosity To see what premium brands use to amplify the signals of their top of the line signal generators I have seen the 1kHz sine distortion spectrum of the analog generator inside an Audio Precision apx555 I am amazed I am attaching it
I think i see absolute perfection
However here there are some informations
https://archimago.blogspot.com/2020/07/pictures-audio-precision-apx555-b.html
so it seems that transistors have still a place in the top performing analog units Good !
i love the smd look ... unfortunately is almost impossibile to use smd with expensive tools But they look gorgeous And the most recent parts have also great specs ...
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i see the cap multiplier as an active filter Maybe i am wrong So before chip fixed regulators could provide a first stage of noise suppression probably in the range where fixed regulators perform worse ? i love fixed regulators a lot They are so convenient to use and cheap as well
Nevertheless also a passive filtering stage with a combination of RC and LC filters could do a similar job I have to study a lot more about passive filters
this is true and also generates a consideration. If a class AB circuit can have excellent performance in terms of THD+noise, why fixate on class A which is certainly more demanding in terms of physical resources?
What if a well-made class AB circuit ultimately sounded better than a class A one ?
With a friend some years ago we compared two power amps he owned ... one in class A and another in class AB After that comparison he sold the class A
Well Ginetto, the name says itself, the active part is multiplying the effect of the capacitor, if the multiplying factor is say 100, then a 10 uF cap will look like a 10 x 100 = 1000 uF, Darlington just increases it, but it's still not a regulator that shaves of the ripple and noise superimposed on the DC voltage, also it will not operate as a cap multiplier if the incoming ripple dives below Vb where it will instead start discharging the capacitor through the transistors base-collector diode back to input and potentially destroy it, some matters to take into account when designing a Cx, however you can also do this with passive parts, just use a much larger capacitor, more foolproof, so what exactly is it you want to do? :)
Hi thank you for the very kind and valuable advice I would stick with one chip fixed regulators Then i read that they are not enough to filter ripple and noise
So the idea is to put something before them I tend to prefer actives because they allow for the use of smaller caps Big ones are big and expensive
I like to keep tiny as possible
If the above is true it could be that some of the criticism about line preamps based on opamps could come from a not perfect power supply
And just a small more attention to filtering could make those preamps shine
I am already aware of some extremely expensive and TOTL commercial preamps using opamps
Moreover someone told me that the secret of great sound is in the power supply
I would like to put everything before the fixed regulators or LM317 The LM317/LM337 option would be more flexible
So the idea is to put something before them I tend to prefer actives because they allow for the use of smaller caps Big ones are big and expensive
I like to keep tiny as possible
If the above is true it could be that some of the criticism about line preamps based on opamps could come from a not perfect power supply
And just a small more attention to filtering could make those preamps shine
I am already aware of some extremely expensive and TOTL commercial preamps using opamps
Moreover someone told me that the secret of great sound is in the power supply
I would like to put everything before the fixed regulators or LM317 The LM317/LM337 option would be more flexible
I use a 8000mAh Lithium battery pack for my DAC and buffer (LME49720) so I don't have ripple or mains noise problems.
The battery pack uses 5 cells per rail, with taps at ~7v for plus & minus 5v via LM317 (soon to be replaced with LT3045/LT3093 very low noise fixed ones) and ~18v for the plus & minus 12v for the opamps and -18v for the -15v regulator.
I have yet to build in the BMS so cells are charged externally once every 2-3 weeks.
I bought the LT3045 and LT3093 regualtors (user programmable) from Aliexpress for about £5 eaach, otherwise I use LM317/337 which tend to be better than the 78/79 types for noise.
The battery pack uses 5 cells per rail, with taps at ~7v for plus & minus 5v via LM317 (soon to be replaced with LT3045/LT3093 very low noise fixed ones) and ~18v for the plus & minus 12v for the opamps and -18v for the -15v regulator.
I have yet to build in the BMS so cells are charged externally once every 2-3 weeks.
I bought the LT3045 and LT3093 regualtors (user programmable) from Aliexpress for about £5 eaach, otherwise I use LM317/337 which tend to be better than the 78/79 types for noise.
Active speakers often open up the sound enormously. But it often doesn't become "blacker", "clearer" or "sharper".
A/B and A: it is more important whether PP or SE.
PP in class A has practically no advantages apart from the lack of or reduced "takeover distortion". It is even a disadvantage for many: these missing distortions show that the ear loves distortions, which give orientation in the sound image. This may be one reason why PP Classe A often performs "more worse" than Classe A/B.
I think you mean active crossovers, not active speakers as there is no benefit from building the amp into the speaker.
Also not sure I agree with "the ear loves distortions" although maybe you have explained why tube amps are popular and why top spec amps can sound cold and clinical.
The former usually use little negative feedback and the latter often use very high amounts of it. It's rather like comparing the lifeless taste of distiled water with natural spring water. Purest does not mean best to human senses.
Hi thank you very much and very interesting indeed I am having a look at the LME49720 datasheet and it is very impressive
Did you use a off the shelf pcb ? i could buy one for those kit on ebay and mount the LME on it
do you have a schematic for the opamp supply ? you get the +/-12VDC from a single 18VAC ? how ? i do not understand
Very interesting and thank you again I am focusing only buffers To get gain and low THD+noise is a challenge indeed The 2nd order harmonics are almost often present Buffers seem to be more linear The chip you recommend is just perfect I have to find a working schematic where is wired as a buffer
All supplies from the Lithium pack which is 5 x 3.6v cells per rail (actually about 20v when fully charged) but can be tapped at 7.2v for 5v to the TDA1541.
I just used stripboard for the LME 49720 as they are 8pin DIPs. I used two to buffer the 4 dac outputs, balanced R2R or dual balanced 1541.
They drive my Sowter I/V transformers which also do the balanced to single ended.
I just used stripboard for the LME 49720 as they are 8pin DIPs. I used two to buffer the 4 dac outputs, balanced R2R or dual balanced 1541.
They drive my Sowter I/V transformers which also do the balanced to single ended.
Sorry, just realised you interpreted ~ as AC when i used it to mean 'approximately'.
I still use regulators to get +-5v from +-7.2 and +-12v and -15v from +-18v.
As I said, there are two banks of 5, 3.6v cells in series, one for the positive rail and one is the negative rail.
So the pack provides: -18, -7.2, 0, +7.2,+18v
s
I still use regulators to get +-5v from +-7.2 and +-12v and -15v from +-18v.
As I said, there are two banks of 5, 3.6v cells in series, one for the positive rail and one is the negative rail.
So the pack provides: -18, -7.2, 0, +7.2,+18v
s
@ginetto61 yes that sounds like a good philosophy, add a first stage simple filter that eliminates the crude stuff cascaded with a good regulator, that's what I would do if I would design the ultimate audiophile gear, at least it leaves one a peace of mind and better night sleep. :)
With regards to power supply affecting the sound of an amplifier or some other cases of audio gears is to some extent depending on their PSRR (Power Supply Rejection Ratio), if you don't mind.. nowadays opamps are so darn well designed and have astronomical PSRR it's almost making diy audio boring. ;(
With regards to power supply affecting the sound of an amplifier or some other cases of audio gears is to some extent depending on their PSRR (Power Supply Rejection Ratio), if you don't mind.. nowadays opamps are so darn well designed and have astronomical PSRR it's almost making diy audio boring. ;(
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Yes, many people are mislead into thinking that the loudspeakers and the listening room have the greatest effect on the listening experience.I've been saying this for a while... lately more often than before... it comes with (old) age and experience:
Sound quality: 99% power supply quality; the whopping 1% is... everything else. No exaggeration..
Hi thank you very much indeed Actually the more i read the more i undrstand that opamps are flooding even the so called high end market when money is no object The problem is that i like simplicity but i am fascinated by complexity You know those line preamps with hundreds of parts ... they seem a work of electronic art
In comparison the small opamps look like beatles
