Not sure about branded but http://www.diyaudio.com/forums/group-buys/145152-lme498xx-driver-power-boards-group-buy.html
Still don't know where it is.I remember it is a US brand.
Dear Panson,
It almost happened in a commercial France (you can guess the brand) active loudspeaker where I design the amplifiers for... but on last moment we decided to go for the LM4702. Subjectively speaking, the LM4702 sounds more "magic" then the LME49810 on the Sanken STD03.
With kind regards,
Bas
Dear Panson,
Yes we did. To be honest in my subjective opinion they sounded the same (despite the fact the LME49811 can deliver slightly more current). I like both 4702 and LME49811 more then the LME49810, but I have to say, all chips sound very good, this is nitpicking and also depends on personal taste. The reason we choose the LM4702 in first instance was more for economical reasons (two channels in one chip, and one heatsink).
However it turned out that I love the sound endless and it was an improvement over the LME49810 we used in the first prototype.
Just be sure you use the Y version of the STD03's with the highest hFE, to keep distortion of the LM4702 low.
It needed some tweaking though. The STD03 needs a pre bias of 2.5mA through it's tempo diode string. Standard the LME4702 gives to much voltage on it's Source and Sink pins. Trim it with just a resistor between source and sink works of course but wasn't totally satisfying for me. (sound-wise and stable current source)
I end up with using a red LED (vf 1.9) in series with a resistor between Source and Sink to set the current on 2.5mA. This works very well, constant, stable and sound significant better then using just a resistor. I will try to add some pictures later this week.
Last but not least, We set the idle bias on 12,5 mV over each Re (Re is 0.22R). Thermal tracking seems very good, and stabilize fast after full power operation.
With kind regards.
Bas
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Dear Panson,
it is an active 3 way studio monitor. 6x LM3886 for the bass, STD03 for mid and high with the LM4702 driver. All amplifiers including PSU are mounted on one and the same board. Crossover and preamp are on separate boards. All signals are differential, the chips are driven differential with no reference to ground. Grounding is a full ground-plane layer without slots. Rectification, and capacitors on board. One of the most silent and hum free amplifiers I've ever designed. THD is below 0.0007% (1Khz 20 watt). I am totally convinced now of good ground-plane designs and I will never go back to star-ground anymore. One just have to know "how"
I can't put pictures online, but if you send me an email I can show you something
With kind regards,
Bas
Example of brand-name amplifier that is based on LME49811? Cary Audio Model 2.300, for example.
Cary Audio Design - News
Dear Panson,
Firstly, Thanks for your email. I will reply them tonight. It are 4 layer boards with one layer dedicated for unbroken ground. The goal was as well to use as less as possible "via" in the audio lines.
The first design was fully LME49810's also for the bass. However the client didn't want to deal with 4 bias potmeters in mass production (2 bias points for mid-high and two bias points for the bass amplifiers in bridge). This was mostly the biggest reason to go for LM3886's after all on the bass. I must say I like the performance on the bass a lot. The LM3886's are very stable and reliable in bridge/parallel if designed well. I did it a bit different then the BPA200 application sheet, but for sure I was inspired by this great app note. For those who want to know, I don't think it would harm to place the concept here of this differential BPA300 concept
With kind regards,
Bas
LM4702 in Arcam Receiver
Hi Everyone,
The High End Arcam Receiver, FMJ AVR600, uses the LM4702. ATI was also going to use it in their multi-chan amplifiers and I saw the measurements on the prototype but I am not sure if that unit ever made it to production. Cary Audio uses the metal can LME49713 opamps in their Exciter DAC.
Also the LME49811 measures slightly better than the LM4702 on THD+N plots. In my listening tests at National the LME49811 was my favorite part (over the 4702 and LME49810 but I was biased as I specified the 49811 for high end mono applications.)
Best Ex-National (and still out of work after 2 years!) "Moss Beach Audio" Regards,
Mark / Audioman54
Hi Everyone,
The High End Arcam Receiver, FMJ AVR600, uses the LM4702. ATI was also going to use it in their multi-chan amplifiers and I saw the measurements on the prototype but I am not sure if that unit ever made it to production. Cary Audio uses the metal can LME49713 opamps in their Exciter DAC.
Also the LME49811 measures slightly better than the LM4702 on THD+N plots. In my listening tests at National the LME49811 was my favorite part (over the 4702 and LME49810 but I was biased as I specified the 49811 for high end mono applications.)
Best Ex-National (and still out of work after 2 years!) "Moss Beach Audio" Regards,
Mark / Audioman54
Dear Mark,
Thanks for your response. I am sorry to hear about your situation
Many of us enjoy your great work, and those LM(E) chips make life easier for engineers. I love the driver chips!With kind regards,
Bas
Yes indeed it does and I don't regret the decision! The 4702 is in the junior AVR500 too (though that one doesn't have the class G additions of the 600 and so doesn't have as much current delivery).
Glad you are still around Mark, though appalled you haven't yet found another decent position.
Sincerely,
John Dawson (ARCAM)
Dear Audioman,
I think you are the only one here who can answer this questions, since there are no internal schematics of the LM4702 available.
How is it possible that the voltage line you send to the mute pin, affect the sound quality so much? We tried different voltage sources for the current needed for the mute function, and with the same calculate current, all solutions give a change in sound. Obviously the cleaner the PSU line to this pin the better the sound quality.
Also this Pin isn't really a good mute function. It switch the whole internal bias off, and is more a "stand by" function then a mute. Once u want to use it as a mute, you need a very very fast switching transistor as switch. We tried it with a relay but the moment between switching is to big and you get a loud "pop" cause of this. Eventually I gave up the mute, and just connect it permanent, and we mute by shorting the inputs.
Any tips or advice is more then welcome.
With kind regards,
Bas
I think you are the only one here who can answer this questions, since there are no internal schematics of the LM4702 available.
How is it possible that the voltage line you send to the mute pin, affect the sound quality so much? We tried different voltage sources for the current needed for the mute function, and with the same calculate current, all solutions give a change in sound. Obviously the cleaner the PSU line to this pin the better the sound quality.
Also this Pin isn't really a good mute function. It switch the whole internal bias off, and is more a "stand by" function then a mute. Once u want to use it as a mute, you need a very very fast switching transistor as switch. We tried it with a relay but the moment between switching is to big and you get a loud "pop" cause of this. Eventually I gave up the mute, and just connect it permanent, and we mute by shorting the inputs.
Any tips or advice is more then welcome.
With kind regards,
Bas
Hello everyone!
As LM4702 and LME49811/10/30 should be related, did you obtain the same behavior by one of the LME chips?
Does anybody now of measurements with separated power supplies for input/output stages on LME powered amps?
I'm planning my first DIY-amp for about two years now (lack of time...), therefor I'm very thankful for any optimization hints. It's gonna be based on LME49811 and AN1850 (thanks for this great document Mark/Audioman54) in conjunction with pansons schematics (thanks a lot too). Thanks for sharing some of your professional experience.
Another question addressing the topic of this thread: Why aren't there more branded amps with this chips on the market?
Best regards,
Oliver
As LM4702 and LME49811/10/30 should be related, did you obtain the same behavior by one of the LME chips?
Does anybody now of measurements with separated power supplies for input/output stages on LME powered amps?
I'm planning my first DIY-amp for about two years now (lack of time...), therefor I'm very thankful for any optimization hints. It's gonna be based on LME49811 and AN1850 (thanks for this great document Mark/Audioman54) in conjunction with pansons schematics (thanks a lot too). Thanks for sharing some of your professional experience.
Another question addressing the topic of this thread: Why aren't there more branded amps with this chips on the market?
Best regards,
Oliver
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