LME49810 - a new cousin for LM4702

Jump to Latest
#122
Some other thougts that someone mayby can answer.

If P = sqrt(P*R) then to calculate P should be P = U * (U/R).

With 100V; 100 * (100/8) = 1250W(!?)...

Im shure that there is some things that i have not consider, can someone tell me what please 🙂 1250W sounds weird...
 
#123
Hi Cj,
you're spot on.
100Vac into 8r0 does indeed give 1250W into 8r0.
But remember to check Ipk and Vpk into the same load.
Vpk=sqrt(P*R*2)
Ipk=sqrt(P*2/R)

for 1250W into 8r0, Ipk=17.7Apk, Vpk=141.4Vpk.
That will require supply rails >=+-150Vdc. and an enormous capacitor bank to hold up while delivering >17Apk.
 
#124
AndrewT said:
Hi Monkey,
I have just gone to your website.
Your advert is completely misleading.
That does not look like a mistake.
That looks more like a deliberate attempt to defraud your customers.
I suggest you change it for something that is much closer to the truth.
Click to expand...


panson_hk said:



It really does! :bigeyes:

Andrew, I like you!
Click to expand...

Guys, I realize you caught the guy but there's no need to burn him for it. A simple "we think you should change your specs or add "with 75V rails" to your description" would have been more courteous. I want Monkey to stick around the forum. His contributions are worthwhile.
 
#125
Matched output transistors

I have purchased MONEKY's board and heatsinks.

I assume they are on the way. He said they were. He has been quick to reply to my emails. Though due to langauge differences my questions have not been answered as completely as I would like.

The main thing is: He always responds. He is OBVIOUSLY not a dishonest man. He is offering what seems to be a useful product,

Iit is expensive to have stuff mailed from China, but that is not his fault.

For those interested I will let it be known when the stuff arrives and "one man's opinion" of what is received.

Does anyone out there know of a source for matched sets of outputs that one could use with MONKEY's board? I am not up to the task and would greatly appreciate knowing of someone who could supply these.

Any suggestions?

THANKS,
 
#127
alexcd said:
Guys, I realize you caught the guy but there's no need to burn him for it. A simple "we think you should change your specs or add "with 75V rails" to your description" would have been more courteous. I want Monkey to stick around the forum. His contributions are worthwhile.
Click to expand...

I fully agree with you. He has apolgized already. Keep in mind that english is not his native language, imagine you have to sell something in china and have to create an ad in chinese.

The letter was not sufficiently detailed expression caused by misunderstanding, expressed regret. And thanks CJ900RR pointed out mistakes, thanks AndrewT the calculation and deduced.
Click to expand...
 
#130
CJ900RR said:
Monkey29 claims that he uses DC-voltage of +-50V and +-45V, and that his construction has 3 Fairchild FJL4215, and 3 Fairchild FJL4315 as output transistors. He also claims that hi's construction delivers 300W into 8 ohm.
Click to expand...


It is impossible. LM49810 has maximin voltage about Vcc-5v, (VCC-10V with the mosfets) , so with +-50v it will be 45v amplitute or ~32V RMS.
This means 128W @8R, even @4R - max output powerl will be only 256W. no 300W. Maybe he used 2R ? 🙂


But I also found a schematic on a russian website using +-100V at the chip, and +-75V at the output transistors (3 * MJL21196 and 3 * MJL21195) and the output power is to be 250W into 8 ohm and 500W into 4 ohm...
Click to expand...

I know this schematic and the author 🙂

As I also have my own experience with 49810, I can't participate to the commin elation.

Barker Clamp - it is good, but short circuit protection is more importand, to my mind, so LME49810 is only a voltage amplifier, 1st stage. It need to be supplied with the output stage, Vbe multiplier to thermal feedback, current protection, DC at the output protection, etc.
It is good to eliminate feedback capacitor using DC-Servo circuit.
Why not to implement all these features inside the chip ?
For example - instead of the stupid "mute" function. As it not zeroed the bias - who need such "mute"? Making the silence?
It should be the function of the front end (pre-amplifier)!

Otherwise - in the big power amlifier we gan nothing! (Especially, in comparison with the PWM Amps).
In the low/middle range - no competition with LM3886/4780 in regular or parallel or bridged implementation (and the sound quality of the 49810 not better then 3886 in INV. with DC-Servo, especially with the vacuum tube buffer as a front end).

P.S. I wrote small article, it is not finished yet, and text is in russian, but schematics and PCBs maybe usefull for somebody - http://altor.sytes.net/Articles/lstone_pre.pdf
Sorry for the slow conection.
 
#131
Received MONKEY's Boards ...

You cannot beat the service!

Everything looks very good.

The heatsinks are drilled, ready to go for final assembly.

ONLY PROBELM, no parts list.

I am sure this is an oversight. Well, I sure hope it is because I do not know how to do this, I guess I could figure it out, but assumed that these were parts for a working amplifier design.

I am writing to MONKEY and asking for the parts list.

Maybe he could post this on his website or here on this forum, unless that would not be allowed.

Rick McInnis
 
#132
Sounds nice. Its a nice looking design and im shure that Monkey will provide you with the partlist. Maybe he just forgott to package it 🙂

Please review it later with sound impression. I have my own version done in Eagle but I havent ordered any boards yet. Need to talk to my work-connections, free boards rock 😀
 
#134
Parts list in email box

I di not have to write.

The parts list was in my email box this morning.

THANKS, Monkey.

The only thing holding this up is what to do for output devices.

Hayenc,

What do you recommend be used? It seems one can use MOSFETs or bipolar devices. The fellow at TECH-DIY.com was helpful and offers matched sets of both types.

I cannot decide what to do; which way to go. It sounds like you have experience with this device and how to use it. May I ask for your help?

This would be simple if the recommended (by Monkey) output devices were readily available in matches sets.

I would appreciate hearing what you think. Expecially on what to do for an output stage!!!!

Thanks,
 
#135
The PCB of my schematic posted earlier in this thread (protection ckt removed). Onsemi's ThermalTrak power BJT is used for the output transistor pairs.
 

Attachments

  • imgp1441.jpg
    imgp1441.jpg
    87.5 KB · Views: 2,742
You must log in or register to reply here.
Top Bottom