LM4702 or LME49810 work in class A mode to drive the output stages in class A/AB - Page 2 - diyAudio
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Old 25th November 2012, 09:18 AM   #11
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hi panson Ive seen an amp from nnexelectronic.com and even on ebay with the above drivers... I have even seen hiraga 30w super class A with a pair of c5200/a1943.

so whats your suggestion for class AB how to achieve like 800w in 8 ohms
for class A may be 60w is also fine...

so how many pairs i can drive using the predrivers A1930/C5171? for class AB..

Last edited by rhythmsandy; 25th November 2012 at 09:20 AM.
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Old 25th November 2012, 09:25 AM   #12
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Here is my LME49810 with Class A biased output THD vs freq for 10 W into 8 Ohm.
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File Type: jpg THD vs freq 10W 8R.JPG (90.1 KB, 292 views)
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Old 25th November 2012, 09:25 AM   #13
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hi panson I have few questions to you...

1. Did u find difference between 49810 and 49811? was that a decent difference?
2. I got polystyrenes as in put its like veil taken out i found much difference just like that if there is difference then it would be great to use lme49811 instead of 810

3. Do you have a schematic of lme49811 to look at?
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Old 25th November 2012, 09:28 AM   #14
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Quote:
Originally Posted by panson_hk View Post
Here is my LME49810 with Class A biased output THD vs freq for 10 W into 8 Ohm.
very impressive distortion figures... nice man...
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Old 25th November 2012, 09:34 AM   #15
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My schematic for 49811 is more or less identical to the data sheet schematic. Here is an example with ThermalTrak output devices (http://www.pansonaudio.com/Compact49...p%20rev2p1.pdf).

Do you familiar with a SPICE program such as LTspice? You can analysis an output stage to determine how many pairs of power devices are needed for 800W, 8 R. Note you need to consider real speaker reactive impedance. Pay attention to beta droop.

The picture shows an output stage (triple EF) with six pairs output devices in LTspice.

Regarding differences between 49810 and 49811. I can't really hear any difference in my system (including my ears). However, bias tuning is easier for 49811.

I don't think you can use 498xx to make a 800 W, 8R amp "directly". The max supply voltage of the chips is +/- 100 V. For 800W, 8R, you need higher than +/-100 V. You may consider bridge mode.
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File Type: jpg output triple EF six pairs.jpg (63.0 KB, 285 views)

Last edited by panson_hk; 25th November 2012 at 09:42 AM.
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Old 25th November 2012, 11:24 AM   #16
AndrewT is offline AndrewT  Scotland
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The 1943/5200 has a cold SOA that has dropped to ~30W @ 100Vce.
That is the sort of voltage you would need to get 500W into 8r0. (89.4Vpk)
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Old 25th November 2012, 03:59 PM   #17
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how are companies like Dynacord making with just 6 pairs they are achieving 1200watts into 4 ohms ive seen the schematic they have just 6 pairs I really suspect the ratings aswell? example Dynacord L2400
technically if the ratings are about 1200watts x 2 then the psu should be about 5kw which they dont have they are the size of 625va x 2 trafos i really dont understand how they can achieve these power outputs...
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Old 26th November 2012, 01:48 PM   #18
AndrewT is offline AndrewT  Scotland
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probably by not using ClassAB
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Old 27th November 2012, 11:39 PM   #19
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SL2400 (newer model) is Class H.
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Old 28th November 2012, 03:16 AM   #20
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yeah it seems class B
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