Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

National's 170w Class D amplifier
National's 170w Class D amplifier
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 2nd May 2002, 05:29 PM   #1
vish_zn is offline vish_zn
diyAudio Member
Join Date: Feb 2002
Location: South Africa
Question National's 170w Class D amplifier


I am currently building National's 170w class D amplifier which uses the LM4651 driver IC and the LM4652 mosfet IC.

I just wanted to know if there is anyone out there who has attempted to build this amp or has any special tips to share with me.

I have searched the forums and only mr partyjups has attempted but not completed this amplifier.

Thanks in advance
  Reply With Quote
Old 7th May 2002, 01:59 PM   #2
JKLman is offline JKLman
diyAudio Member
Join Date: May 2002
Location: Sweden
Hi vish_zn

I am also interested in building a class-D amp but havent found alot of schematics for this. Do you have one for this you like to share?
  Reply With Quote
Old 7th May 2002, 05:06 PM   #3
tsz is offline tsz  Sweden
diyAudio Member
Join Date: Aug 2001
Location: Göteborg, Sweden
Send a message via ICQ to tsz

Take a look here: http://www.elfa.se/elfa/produkter/se/20/2022041.htm

Schematic here: http://www.elfa.se/images/lw_hires/B21342_1.GIF

Looks like an interesting project.
  Reply With Quote
Old 7th May 2002, 05:32 PM   #4
vish_zn is offline vish_zn
diyAudio Member
Join Date: Feb 2002
Location: South Africa
Hi Jonas
The problem that im experiencing at the moment is actually getting the board done from the schematic but here is the link for the .pdf document that national supplies you with.

http://<a href="http://www.national....M4652.html</a>

This document has a schematic diagram and the board layout but National also supplies you with a design guide. If you use this design guide you will definitely not be using the same layout. Im not sure what the correct link for the design guide is but if use google to search for it im sure youll come up with something. The design guide is really helpful and im almost complete with this project. It wasnt that hard but the main problem was sourcing the i.c's here in South Africa.

Please use google to search for "LM4651" and "LM4652". The 4651 is the driver ic for the 4652(which contains 4 mosfets).

Please feel free to email me as i dont visit the forum regularly.

hope i was of some help to u.
  Reply With Quote
Old 7th May 2002, 07:29 PM   #5
JoeBob is offline JoeBob  Canada
diyAudio Member
JoeBob's Avatar
Join Date: Nov 2001
Location: Montreal, Canada
Interesting enough I just got some of those parts in the mail today. I was planning on building a pair as well.

Are you intending on using national's typical aplication? I was wondering how high a frequency one could get out of them. It's says it's a "subwoofer" amplifier, but by using a higher switching frequency one should be able to get better responce in the higher frequencies, correct.
  Reply With Quote
Old 8th May 2002, 02:08 PM   #6
partyjups is offline partyjups
diyAudio Member
Join Date: May 2001
Location: Denmark
Default pcb layout double side

Hi I have the pcb layout fron the applications note.

I make it up bye taking the difrent layers and put on top of eachother in paint shop I can post to any one but need e-mail adress.

partyjups jc dk.
  Reply With Quote
Old 8th May 2002, 02:23 PM   #7
Opie is offline Opie
diyAudio Member
Join Date: Oct 2001
Location: UW Stevens Point Campus
Default pcb

I would like a copy of the pcb.

My address is boppe069@uwsp.edu

  Reply With Quote
Old 8th May 2002, 05:22 PM   #8
pdogg is offline pdogg
diyAudio Member
Join Date: May 2002
Location: Farmington, MI
I built an amp with these components and it seems to work as advertised but there are some issues to keep in mind when designing the board.
I ran into protection/shutdown problems and destroyed 3 of the transistor ICs because I had the wrong type of inductor. If possible, use the inductors specified in the reference design!!
Do NOT use a toroidal choke! I did and apparently it saturated too easily at these frequencies and caused too much current to flow thru the MOSFETs. Make sure you use a coil with a DC current rating of at least 10 amps to be sure. If the current rating is too low, the coils will overheat and also saturate and destroy the transistors. I have seen suitable coils in the digi-key catalog which I will try next, part M6346-ND.
The bandwidth seems to be limited to around 10k. Increasing the switching freqency will cause a decrease in the power output and will affect efficiency and increase distortion. It seems that the IC internally limits the bandwidth somewhat, and 20kHz operation is unlikely even with increased switching speed.
Keep the traces to the MOSFET module as short as possible and avoid crossing any low-level signal traces. The square wave control signal emits a lot of RF energy so the traces should be run over a ground plane if possible.
  Reply With Quote
Old 8th May 2002, 05:44 PM   #9
peranders is offline peranders  Sweden
Electrons are yellow and more is better!
diyAudio Member
peranders's Avatar
Join Date: Apr 2002
Location: Göteborg, Sweden
National's 170w Class D amplifier
Default Juicy amps....

Have you checked Bang & Olufsson's extreme class-D(?) amps?

500 Watts in 3.6 x 3.6 x 1 inches!

They have also a 1000 Watts module.

The modules are sold as components but only for OEM! Swedish readers of High-Fidelty were able to buy a EV-board for 400 USD. 2 x 500 Watts with a switched PSU.

/Per-Anders (my first name) or P-A as my friends call me
Group buy: DCT03 DC trap for big toroidal transformers. Sign up for interest HERE. 18 pcb's in interest.
  Reply With Quote
Old 22nd May 2002, 05:25 AM   #10
Tekguy is offline Tekguy
diyAudio Member
Join Date: May 2002
Location: Illinois, USA
Post Why use National's output IC?

I ordered some samples of the controller IC, but I intend to make my own H-bridge output stage with larger mosfets. I'm considering possibly using IRFZ24 or IRFZ44 types. I have large quantities of N-channel mosfets to try out. I'll probably create the driver board separate from the output board so that I can try different output devices without too much hassle. Has anyone else tried this? It seems that National's ICs are always lacking when it comes to the ability to handle any real power.
  Reply With Quote


National's 170w Class D amplifierHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
FS: National Overture Class-D Demo Board Amp speaker Swap Meet 3 24th March 2009 04:05 PM
WTS: National 170W Class-D Amp Demo Board speaker Swap Meet 1 3rd March 2008 03:41 PM
I don't know how to go to the page that have audio power amplifier ic at national.com jinkuchi Chip Amps 5 16th May 2005 05:06 AM
Class D amplifiers on National Chips jmateus Chip Amps 4 8th April 2005 07:10 AM
National's 170w Class D amplifier Inductors KarlP Solid State 3 5th June 2002 12:21 AM

New To Site? Need Help?

All times are GMT. The time now is 10:37 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio