LM4702 or LME49810 work in class A mode to drive the output stages in class A/AB

[rhythmsandy]

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..

[panson_hk]

Here is my LME49810 with Class A biased output THD vs freq for 10 W into 8 Ohm.

[rhythmsandy]

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?

[rhythmsandy]

Originally Posted by panson_hk

Here is my LME49810 with Class A biased output THD vs freq for 10 W into 8 Ohm.

very impressive distortion figures... nice man...

[panson_hk]

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.

[AndrewT]

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)

[rhythmsandy]

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...

[AndrewT]

probably by not using ClassAB

[panson_hk]

SL2400 (newer model) is Class H.

[rhythmsandy]

yeah it seems class B