Hi Everyone,
I do have a little knowledge of Nationals new line of LME parts. The following should shed a little light on these LME High Performance Audio parts.
The LME49811 is a mono version of the LM4702 with a few layout modifications that improve low level performance. The output stages on both of these parts are set up for class A operation. The Stereo LM4702 has 5 ma of output current capability and the Mono LME49811 has 7ma. This amount of current drive capability limits the max power a designer can get out of an amplifier using normal compound bipolar output stages.
The LME49810 was designed for much higher output current, 50ma, but required the addition of an internal class AB output stage to get that extra drive capability.
I have listened to amplifiers built out of all three parts and because they all come from the same designer and share the same HV process, +/- 100VDC!, they sound very similiar. The LM4702 is the part to use for stereo and balanced applications, the LM49810 for mono higher power applications, and the LME49811 for mono purist designs.
I presently have a LM4702 stereo amplifier based on National Semi's app note AN1490 that I have been listening to for over a year. It is direct coupled and has no output protection (except for 6A fuses in the +/- 50VDC power supply lines). I turned off my KSA300S and mono block Symphonic Line RG-4's and now use the LM4702 amp as my home reference. Hard to beat .0004% THD+N at full power in a finished design.
I am also using National's new LME opamps in my D/A design. I replaced the AD811's I was using with Nationals LME49713's. I like the sonic qualities of the current feedback opamps, LME49713's, the best but for certain places in my signal path were current feedbacks are not optimal I use the LME49710HA metal can parts. (Note: National will be releasing the LME49713's in the same HA metal cans as the VFB LME49710/20HA's quite soon. In my listening tests the metal can parts always sound better than the dip parts but they measure about the same?... and they are more expensive!)
One other point that I believe is very important...I am told that the LME parts are built so that the physical structures of the NPN and PNP devices are identical in every way! This could be one reason for the great sonic qualities of these parts. But without question .00005 %THD in an opamp at 1.9 nV noise (LME49713) is hard to beat.
Happy Listening Everyone,
Audioman55
I do have a little knowledge of Nationals new line of LME parts. The following should shed a little light on these LME High Performance Audio parts.
The LME49811 is a mono version of the LM4702 with a few layout modifications that improve low level performance. The output stages on both of these parts are set up for class A operation. The Stereo LM4702 has 5 ma of output current capability and the Mono LME49811 has 7ma. This amount of current drive capability limits the max power a designer can get out of an amplifier using normal compound bipolar output stages.
The LME49810 was designed for much higher output current, 50ma, but required the addition of an internal class AB output stage to get that extra drive capability.
I have listened to amplifiers built out of all three parts and because they all come from the same designer and share the same HV process, +/- 100VDC!, they sound very similiar. The LM4702 is the part to use for stereo and balanced applications, the LM49810 for mono higher power applications, and the LME49811 for mono purist designs.
I presently have a LM4702 stereo amplifier based on National Semi's app note AN1490 that I have been listening to for over a year. It is direct coupled and has no output protection (except for 6A fuses in the +/- 50VDC power supply lines). I turned off my KSA300S and mono block Symphonic Line RG-4's and now use the LM4702 amp as my home reference. Hard to beat .0004% THD+N at full power in a finished design.
I am also using National's new LME opamps in my D/A design. I replaced the AD811's I was using with Nationals LME49713's. I like the sonic qualities of the current feedback opamps, LME49713's, the best but for certain places in my signal path were current feedbacks are not optimal I use the LME49710HA metal can parts. (Note: National will be releasing the LME49713's in the same HA metal cans as the VFB LME49710/20HA's quite soon. In my listening tests the metal can parts always sound better than the dip parts but they measure about the same?... and they are more expensive!)
One other point that I believe is very important...I am told that the LME parts are built so that the physical structures of the NPN and PNP devices are identical in every way! This could be one reason for the great sonic qualities of these parts. But without question .00005 %THD in an opamp at 1.9 nV noise (LME49713) is hard to beat.
Happy Listening Everyone,
Audioman55
Alant4321,
Thanks for the comments.
I just read my post again and realized I left out one important point. The LME Opamps when used with the new LME49600 300ma buffer connected to their outputs to boost the output current make great power power supplies for all line level circuits using the LME parts. I run the rails in my D/A preamp at +/-18VDC with a LM329 6.9V zener reference connected to the unregulated rails and a simple cap filter. Put the buffer inside the feedback loop and set the gain resistors for the desired output voltage and you have a great power supply regulator. The often used "Standard" LM78/79-5-12-15VDC regulators are awful for audio signal path circuits and should never be used!
Hope we get to hear from more people using these great new parts.
Audioman55
Thanks for the comments.
I just read my post again and realized I left out one important point. The LME Opamps when used with the new LME49600 300ma buffer connected to their outputs to boost the output current make great power power supplies for all line level circuits using the LME parts. I run the rails in my D/A preamp at +/-18VDC with a LM329 6.9V zener reference connected to the unregulated rails and a simple cap filter. Put the buffer inside the feedback loop and set the gain resistors for the desired output voltage and you have a great power supply regulator. The often used "Standard" LM78/79-5-12-15VDC regulators are awful for audio signal path circuits and should never be used!
Hope we get to hear from more people using these great new parts.
Audioman55
Add two more remarks:
1) People may not know how to apply Opamp between LME98710 and LME98713. Let do the comparison as below:
=> LME49710 is Opamp with ¡§voltage feedback¡¨ and LME9713 is Opamp with ¡§current feedback¡¨.
=> LME49713 has much higher slew rate and wide gain bandwidth, and even lower noise than the LME49710.
=> One disadvantage for the LME49713 is regarding to stability from stray capacitance on any node to ground, and also in the feedback path. Even a couple pico-Farads will cause several dB of peaking in the frequency response. However, audio frequency is not so high, thus not to cause a major problem.
=> The voltage feedback LME49710 has better THD+N. We've seen more people use the LME49710 in preamps and in active filters. If you don't need the higher frequency and slew rate the LME49713 has, then the LME49710 is a good selection.
=> Both LME49713 and LME49710 can be used in signal path of DAC and pre-amplifier, but may exist two different sounds. You may make a research to justify which sound you like. Normally, people prefer the sound of LME49713.
=> The best thing is to breadboard each one (will need different components and circuitry) and see which one sound better. In audio, there is science and measurements, but ultimately it is what your ears say.
2) The "metal can" package for LME49713 is still in development and testing. It should be released in the fall time-frame.
B. regards,
alant
1) People may not know how to apply Opamp between LME98710 and LME98713. Let do the comparison as below:
=> LME49710 is Opamp with ¡§voltage feedback¡¨ and LME9713 is Opamp with ¡§current feedback¡¨.
=> LME49713 has much higher slew rate and wide gain bandwidth, and even lower noise than the LME49710.
=> One disadvantage for the LME49713 is regarding to stability from stray capacitance on any node to ground, and also in the feedback path. Even a couple pico-Farads will cause several dB of peaking in the frequency response. However, audio frequency is not so high, thus not to cause a major problem.
=> The voltage feedback LME49710 has better THD+N. We've seen more people use the LME49710 in preamps and in active filters. If you don't need the higher frequency and slew rate the LME49713 has, then the LME49710 is a good selection.
=> Both LME49713 and LME49710 can be used in signal path of DAC and pre-amplifier, but may exist two different sounds. You may make a research to justify which sound you like. Normally, people prefer the sound of LME49713.
=> The best thing is to breadboard each one (will need different components and circuitry) and see which one sound better. In audio, there is science and measurements, but ultimately it is what your ears say.
2) The "metal can" package for LME49713 is still in development and testing. It should be released in the fall time-frame.
B. regards,
alant
Does anyone have any news about these amplifiers?
I'll try an amp with LME49830 with Exicon lateral mosfets. They have(at least in the datasheet) quite low capacitances, Ciss 500pf for N channel and 700pF for P channel devices and Crss 10pF for N and 25 for P. How many do you think I can drive(without additional stages)?
Also, I have seen in an app-note that 2-pole compensation gives better sonic results, what do you think about it?
I'll try an amp with LME49830 with Exicon lateral mosfets. They have(at least in the datasheet) quite low capacitances, Ciss 500pf for N channel and 700pF for P channel devices and Crss 10pF for N and 25 for P. How many do you think I can drive(without additional stages)?
Also, I have seen in an app-note that 2-pole compensation gives better sonic results, what do you think about it?
Hi Gopher,
Sorry for the delay answering you but I have been very busy with AES (I was able to give a presentation on audio low level power supplies with Bob Pease which was a lot of fun) and then I had hernia surgery.
I am writing an ap note for the D/A Preamp and should have it ready in a month or so. I have been asked those above me not to post the schematic until I get that done. (I did put it up on the screen during our presentation but did not include it in the handouts after the presentation). The new power supplies, the cap-less output stage and the LME49713HA metal can current feedback opamps are the keys to the units outstanding sound quality. I would suggest getting some of those parts and trying them. My D/A uses an AKM front end (I used the AK4396 but the new AK4397 should be a bit better for the specs).
Best Regards,
Audioman55
Sorry for the delay answering you but I have been very busy with AES (I was able to give a presentation on audio low level power supplies with Bob Pease which was a lot of fun) and then I had hernia surgery.
I am writing an ap note for the D/A Preamp and should have it ready in a month or so. I have been asked those above me not to post the schematic until I get that done. (I did put it up on the screen during our presentation but did not include it in the handouts after the presentation). The new power supplies, the cap-less output stage and the LME49713HA metal can current feedback opamps are the keys to the units outstanding sound quality. I would suggest getting some of those parts and trying them. My D/A uses an AKM front end (I used the AK4396 but the new AK4397 should be a bit better for the specs).
Best Regards,
Audioman55
Alright, just ordered two complete LME49830TB/MOSFET kits (2x amplifier, 2x power supply, 2x volume control) from CP Design www.chip-pcb.cn so I should be getting them in shortly (picked EMS shipping).
As I'm one of the designers of the ExtremA amplifier (ExtremA, a reference class-A DIY amplifier. - Introduction) and design amplifiers and similar equipment on a regular basis I'm going to put the LME49830TB/MOSFET design through its paces and certainly look at the performance and whether the design lives up to the claims made in the datasheet.
Cheers,
Sander Sassen
Hardware Analysis - Computer hardware news, reviews and forums that provide help and assistance with problems.
As I'm one of the designers of the ExtremA amplifier (ExtremA, a reference class-A DIY amplifier. - Introduction) and design amplifiers and similar equipment on a regular basis I'm going to put the LME49830TB/MOSFET design through its paces and certainly look at the performance and whether the design lives up to the claims made in the datasheet.
Cheers,
Sander Sassen
Hardware Analysis - Computer hardware news, reviews and forums that provide help and assistance with problems.
LME49810 is perhaps the best peforming chip.
At least when used with BIPOLAR Power transistors.
And AndrewT is right. Because LME49830 are to drive MOSFET.
For example IRFxxx/IRF9xxx.
But I know LME49830 has been tested with LATERAL MOSFET, as well
Like 2SK1058 / 2SJ162
See some testdata in this National application PDF, for LME49830
AN-1850: LME49830TB Ultra-High Fidelity High Power Amplifier Reference Design
http://www.national.com/an/AN/AN-1850.pdf
Lineup regars
Hi
Do you have a schematic for this LME49830 with LATERAL MOSFET 2SK1058 / 2SJ162 ?
Thanks
I'm thinking of building one with LME49810 or LME49811. I have one denon amplifier transformer, don't know exact voltage but those large caps says 63v so below that. I have few output transistor also, D2390/B1560 and C4468/A1695.
I have done schematic by using typical application in datasheets. So that denon apmlifier can do 80w/8ohm, so i can probably do that too?
Schematic->https://www.dropbox.com/s/r5y8lce9bmdvrxk/Amp.PNG
That uses LME49810. So any advice about adding or removing components from that schematic?
I have done schematic by using typical application in datasheets. So that denon apmlifier can do 80w/8ohm, so i can probably do that too?
Schematic->https://www.dropbox.com/s/r5y8lce9bmdvrxk/Amp.PNG
That uses LME49810. So any advice about adding or removing components from that schematic?
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