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Old 29th July 2008, 02:29 AM   #1
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Default Idiot's Guide to the 49810TB

On the advice of my (admittedly slightly mad) audio guru, I'm assembling a pair of active three-way speakers. To power them, I need a six-channel amplifier on a student budget. (The drivers are currently being amassed.) Low heat output is a major plus.

On another audio forum, I recently found a six-channel Rotel amplifier. While it is very well made and quite cheap, it's rated for a paltry 30 watts per channel, which leaves not much in the way of headroom.

Hoping to find a similarly economical solution, I headed over to the chipamp forum, and found the LM49810TB, which (so far as I can tell) takes an audio signal on the input and provides the requisite voltage outputs to drive a pair of output transistors with very low distortion and very high efficiency. Unlike its predecessor, the LM4702, it actually produces enough current to properly drive MOSFETs instead of darlingtons. It's even cheap - National Semiconductor will send me five samples for $14 shipped.

There is, of course, a major stumbling block - my lack of electronics skills. Beyond a few simple Gainclones and simple kits, I've not built very many things.

While searching for kits, I found CP-DESIGN. (http://www.chip-pcb.cn/en/M-9810-C.htm). However, the only person I found on the forum who has built the kit has had much difficulty getting it to work, and the pricetag - $43 per module plus halfway-round-the-world shipping - is steep for a six-channel amp. They also do a LM4702-based design at $60 for two channels, but from what I've read, these will not likely sound as good.

I've got some great big power toroids in the basement that are somewhere near 60v AC with a center-tap. Should I go for a DIY design, fork out the cash for a kit, or buy the Rotel?
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Old 29th July 2008, 03:26 AM   #2
lineup is offline lineup  Sweden
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For the MOSFET driving
I suggest you use LME49830 instead.
It was designed especially for MOSFET use.
While the other is for BIPOLAR power transistors.

Read all our discussions in this active topic:
National LME49810TB/LME49830TB UltraHighFidelity HighPower Amplifier Reference Design
National LME49810TB/LME49830TB
UltraHighFidelity HighPower Amplifier Reference Design



You will find some evaluation circuits and test results
using LME49830 + HEXFET MOSFET or using Lateral MOSFET 2SK1058/2SJ62
in the LME49830 datasheet and application note:
LME49830
- Mono High Fidelity 200 Volt MOSFET Power Amplifier
- Input Stage with Mute
http://www.national.com/ds.cgi/LM/LME49830.pdf
http://www.national.com/an/AN/AN-1850.pdf


Regards Lineup
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Old 29th July 2008, 04:09 AM   #3
ttan98 is offline ttan98  Australia
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Default Re: Idiot's Guide to the 49810TB

Quote:
Originally posted by Spasticteapot

While searching for kits, I found CP-DESIGN. (http://www.chip-pcb.cn/en/M-9810-C.htm). However, the only person I found on the forum who has built the kit has had much difficulty getting it to work, and the pricetag - $43 per module plus halfway-round-the-world shipping - is steep for a six-channel amp. They also do a LM4702-based design at $60 for two channels, but from what I've read, these will not likely sound as good.

Hi,

I bought the BJT version of LME49810 from Chip-pcb, and I built it from scratch, and I found it to be quite straight forward. The service from them is fair as I suspect he works in another job. I bought quite a few parts from them and I had no problems.

Current most parcels sent out of China has to go through DHL(expensive) for I think for security reason because of the Olympics. After the event I suspect Chip-pcb will revert back to using China post which is much cheaper. I may buy more parts when he reverts back to using China post.

cheers.
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Old 29th July 2008, 04:12 AM   #4
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Default Re: Re: Idiot's Guide to the 49810TB

$300 + power supply is a bit out of my league.

Perhaps similar performance could be obtained from a freely available design? I can etch PCBs and have access to a drill press, and I have some absolutely enormous heatsinks.
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Old 29th July 2008, 04:54 AM   #5
lineup is offline lineup  Sweden
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Default Re: Re: Re: Idiot's Guide to the 49810TB

Quote:
Originally posted by Spasticteapot
$300 + power supply is a bit out of my league.
I can etch PCBs and have access to a drill press,
and I have some absolutely enormous heatsinks.
Spastic
this is the way I would go, too
No need to buy some extra expensive stuff to use LME49830 drive a couple of MOSFET.

You have several circuits in those two datasheets/application PDF
and there will be plenty of FREE diyaudio schematics/PCB layouts posted

You just wait, 1-2 months, and see
It is bit early these days
those chips has not been known for very long
but will be

LM3875 = Gainclone has been known to diyaudio community for maybe 20 Years, now?

Regards
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Old 29th July 2008, 06:16 AM   #6
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i have built 3 amps based on the LME49810, they have all worked just right and sound grate, every one of the amps i built was a better version of the previous one. i have no back ground in electronics, which should tell you how easy it is to build an amp based on this chip.
if you check some of the transistor manufactures, you'll find that for the cost of shipping they'll send you about $250 dollars worth of transistors of your choice. for testing of course at no extra charge, there are a bunch of component manufacturers that provide samples in that manner and deppending of your email account type they wont even charge you for shipping.
which makes testing your first amps cheap. specially if you're like me and burn a bunch of parts during first start. lol

But Please dont abuse their sample service.

here is a link to one site i found which is very helpful since they sell the kit, but also provide the schematics, part lists and its all in pdf format.
that should give you an idea, i suggest you do a search on this site for the LME49810, which should bring up all the projects on here based on the chip with pretty much all the info you need to know to design and build your amp.

here are the links i like the most, i have also seen a couple of kits based of off these amps on this links. they are worth a look.
http://www.power-amp.eu/power-amp.e/ax1300.htm
http://www.power-amp.eu/power-amp.e/ax1400.htm
http://www.power-amp.eu/power-amp.e/ax1600.htm

check the bottom of the page, where youll find the links with these names ,SchematicPCB, LayoutComponent, SiteSolder, SiteMeasuring, ResultsPhoto theyll link you to the files.

let us know of your progress, i love to get my hands on any new knowledge base on this chip.
laters
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Old 29th July 2008, 07:00 AM   #7
lineup is offline lineup  Sweden
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they look very nice

Operation Instructions here:
http://www.power-amp.eu/power-amp.e/downloads.htm

Here is one photo from
http://www.power-amp.eu/power-amp.e/ax1600.htm
Click the image to open in full size.

here is another viewClick the image to open in full size.
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Old 29th July 2008, 07:21 AM   #8
Nuuk is offline Nuuk  United Kingdom
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You don't have to rule out chip amps for an active three-way, as you can see here .
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
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Old 29th July 2008, 07:26 AM   #9
lineup is offline lineup  Sweden
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Quote:
Originally posted by Nuuk

.. chip amps for an active three-way, as you can see here .

True! Nuuk.
Actually, Power Amplifier Chips, like LM3875, are almost ideal,
for quickly and easily making a very good Active Speaker system.

Choice can be,
if you want to put those chip power amplifiers into Speaker Box.
Close to speaker drivers.

Or you have the amplifiers in one place,
along with controlling preamp + active crossovers,
and have only your speaker drivers in the Speaker cabinet.
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Old 29th July 2008, 01:44 PM   #10
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I have a lot of FQA12P20/FQA19N20C mosfets and 2SC5200/2SA1943 power transistors; which would be the best combination?

LME49830 + FQA12P20/FQA19N20C

or

LME49810 + 2SC5200/2SA1943
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