Hi Szabolcs,
There was a very nice set of drivers made by National Semiconductors exactly for that purpose but unfortunately they are no more produced
I put the Application Note in case you find some on the Web : http://ivanaudiomaster.narod.ru/AN-1850.pdf
For info, I have built one amplifier with triple Thermal Track power transistors push-pull with very good result
Rgds,
Marc
There was a very nice set of drivers made by National Semiconductors exactly for that purpose but unfortunately they are no more produced
I put the Application Note in case you find some on the Web : http://ivanaudiomaster.narod.ru/AN-1850.pdf
For info, I have built one amplifier with triple Thermal Track power transistors push-pull with very good result
Rgds,
Marc
Dear Marc, thanks a lot for the quick and valuable reply. Exactly this is im looking for. And i had very good experience with the head phone amplifier(lme49200 with lme49720) from this series -sound wise. I really would like to keep it simple and this mosfet solution with integrated driver seems to be an optimal solution.
So according tpur info there is no substitution or successor model?
Thanks again Szabolcs
So according tpur info there is no substitution or successor model?
Thanks again Szabolcs
In general "audiophile" and driver IC do not mix. An IC involves a number of compromises in order to integrate the circuit in a single monolithic chip. A chip has a polarity that suites either NPN or PNP transistors but not both. So most any amp considered "audiophile" will use discrete transistors.
And most op-amp based circuits requires as much "glue" to adapt the op-amp for high voltage etc as is required to make a discrete circuit without the op-amp. ie the op-amp saves nothing and results in performance compromises.
And most op-amp based circuits requires as much "glue" to adapt the op-amp for high voltage etc as is required to make a discrete circuit without the op-amp. ie the op-amp saves nothing and results in performance compromises.
Good engineering cares about performance, not prejudice, and modern opamps are very high performing. 0.000015% distortion is available in opamp format for instance (OPA1612). The compromises are finessed completely by smart circuit design, to produce something several orders of magnitude better than discrete power amps can achieve in fact. Not that you need that level of linearity, but to achieve it shows that opamps can be way better than needed for "audiophile" whatever that means.
The advantages of using a monolithic chip include being able to use extremely well matched components which are strongly thermally matched, laser trimming, and very low sensitivity to external noise. Worrying about whether the substrate is n-type or p-type is irrelevant these days, sophisticated ion-implantation techniques are available to get any doping profile you want. Its not the 1970's any more, IC processes are way more sophisticated.
The point about glue to get a 10Vrms signal upto output levels is very true though, typically it doesn't reduce the BOM cost to use an opamp front end, and the problem area in amps that is hard to improve is not the front end anyway, its the cross-over behaviour and biasing stability.
Since the focus for integrated amp chips is class-D these days, its unlikely we'll see any new integrated amp chips with modern opamp levels of performance, because the volume market doesn't exist.
The advantages of using a monolithic chip include being able to use extremely well matched components which are strongly thermally matched, laser trimming, and very low sensitivity to external noise. Worrying about whether the substrate is n-type or p-type is irrelevant these days, sophisticated ion-implantation techniques are available to get any doping profile you want. Its not the 1970's any more, IC processes are way more sophisticated.
The point about glue to get a 10Vrms signal upto output levels is very true though, typically it doesn't reduce the BOM cost to use an opamp front end, and the problem area in amps that is hard to improve is not the front end anyway, its the cross-over behaviour and biasing stability.
Since the focus for integrated amp chips is class-D these days, its unlikely we'll see any new integrated amp chips with modern opamp levels of performance, because the volume market doesn't exist.
Ok if i do not use the audiophile word just a very good sounding but simple amplifier.
As Marc had the idea. Regarding the lme 49830.
Im sure real audiophile uses discrete elements but you can reach good result with ICs too. As I have written I have very good experience with the lme49600 + lme49720 combo. Maybe far from audiophile but I like the really clear sounding with nice stage (driven by an old CD and a modding ed. DAC. WITH HIFIMAN 400.
so IM looking for something similar which might not perfect. But really good and really simple.
Thanks for your answer.
Short question. Do you have any suggestion for this monolitic solution.
I mean which is a good sounding one.
(Naturally which is not class D but A or A/B). Thanks again.
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What about a bootstrapped opamp that allows high voltage rails and drive complementary MOSFET output stage?
Like this for front end:
Surjan Dogran's Easy Peasy 70v peak-peak Opamp for $1
Pair with typical output stage.
Article on supply bootstrapping by Danyuk
https://www.proaudiodesignforum.com...anyuk_Electronic_Design_September_11_2008.pdf
Or this:
Or this:
Like this for front end:
Surjan Dogran's Easy Peasy 70v peak-peak Opamp for $1
Pair with typical output stage.
Article on supply bootstrapping by Danyuk
https://www.proaudiodesignforum.com...anyuk_Electronic_Design_September_11_2008.pdf
Or this:
Or this:
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op-amp input
This is an example of an op-amp based power amp.
The output requires gain because the maximum voltage a typical op-amp can handle is +/-15V. Most op-amps are designed for minimum unity gain based on their own phase margin without extra stages in the feedback loop, so adding stages results in stability problems which require some tricky feedback. This circuit does not use the op-amp rails as outputs, but that is a common idea in such amps, however many spice models do not support rail pin outputs so the simulation fails.
This circuit features a single 48VDC supply for a useful 65Watts into 4 Ohms, ie not too little and not too much. Distortion is about 0.0018%, ie good if not audiophile.
This is an example of an op-amp based power amp.
The output requires gain because the maximum voltage a typical op-amp can handle is +/-15V. Most op-amps are designed for minimum unity gain based on their own phase margin without extra stages in the feedback loop, so adding stages results in stability problems which require some tricky feedback. This circuit does not use the op-amp rails as outputs, but that is a common idea in such amps, however many spice models do not support rail pin outputs so the simulation fails.
This circuit features a single 48VDC supply for a useful 65Watts into 4 Ohms, ie not too little and not too much. Distortion is about 0.0018%, ie good if not audiophile.
Attachments
Yes, I quite like the idea of bootstrapping, an op-amp or at least the VAS. But you must realize that the bootstrap voltage creates a huge common mode voltage on the +/- inputs. So there is a limit on how much voltage swing you can add. The chip rails can never become reverse polarity wrt the inputs, ie the negative rail max is a bit below zero volts and the positive rail minimum is a bit above zero volts.
The idea of bootstrapping the VAS (only) is a great way to get ~rail to rail output, especially with MOSFET outputs that have a significant vto voltage.
Attached is a op-amp with a 2EF buffer that is 50% bootstrapped.
Instead of bootstrapping rails, it is safer to use high voltage op amps like:
LTC6090 +70v, -70v rails. 12Mhz BW, 21V/μS SR.
OPA454 +50v, -50v rails.
ADA4700-1 +50v, -50v rails.
If not enough go bridged mode for double the voltage.
And use CCS at the bias spreader for near rail to rail drive.
LTC6090 +70v, -70v rails. 12Mhz BW, 21V/μS SR.
OPA454 +50v, -50v rails.
ADA4700-1 +50v, -50v rails.
If not enough go bridged mode for double the voltage.
And use CCS at the bias spreader for near rail to rail drive.
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