Class G/H

[nag1_uk]

Hi all,
I have just completed my form for my 3rd year project. I am to make either a class G or H audio amp ( my own choice).
I read up on what the terms mean and they both sounded interesting.
Has anyone got any tips on what to look out for when designing this amp. I think the Class H looks a better design that modulates the voltage rails so I would really like to takle that problem

I have buit a few amps in the past, but not designed on as yet so really looking forward to it.

Thanks for any info

Mike Cole

 

[subwo1]

Do Not Dally

It is an interesting but challenging project. Have fun.

 

[richie00boy]

I think Doug Self published a class-g design in Electronics World a few years ago.

 

[rtirion]

The 1977 Sano patent nr. 4,115,739 could be of interest.

Regards

 

[Steven]

Class H in the easy way: http://www.semiconductors.philips.com/acrobat/datasheets/TDA1560Q_4.pdf

Steven

 

[thanh]

Steven! What's about discrete class H?
What is the difference between class AB and class H?
Who have just succeeded in building a class H amp?

 

[nag1_uk]

The 1977 Sano patent nr. 4,115,739 could be of interest.

Regards

How do I find any thing on what you have suggested?


Thanks for all info.

I am interested in making a descrete unit but thanks for the linkl to the IC.

I have a while before I have to buile this yet so I will keep looking for info for now.

Thanks to all

Mike

 

[rtirion]

US Patent Office

You can find the patent at the US patent office

http://www.uspto.gov/

Use Patent Search | Patent Number Search | fill in 4,115,739

You will see an abstract. Click on Images to see the actual page.
You will need a TIFF viewer.

Hope this helps

Regards

 

[rtirion]

Tiff viewer plugin

Tiff viewer plugin for IE6 can be found here

http://www.alternatiff.com/

Regards

 

[sam9]

BTW, the Self class D is available in kit form. Obviously that's cheating for a 3rd year project.

Since one of the reasons for the class is to reduce the physical size of the amp, one of the key elements is getting your hands on an appropiate transformer such as a 35-18-0-18-35. Obviously you could use two but that kind of negates some of the objectives. A true DIY fanatic would wind his own, of course.

 

[Steven]

Steven! What's about discrete class H?
What is the difference between class AB and class H?
Who have just succeeded in building a class H amp?

I have no 'simple' discrete class H circuit at hand. Some more complex circuits can be found on the web, like the ones from QSC.

A class H circuit often uses the charge pump principle to charge a capacitor which is switched in series with the normal supply voltage during signal peaks exceeding the normal supply voltage. This does not require additonal secondaries of the transformer. The TDA1560, mentioned above, even works on a single supply voltage. Using a bridged amplifier (BTL) with floating feedback you can use a single charge pump to boost the supply voltage for both positive and negative signal peaks.

The mentioned patent from Sano is a special case class H amplifier. Actually it is a high efficiency class A amplifier using a class B amplifier as power supply. Normally this is not considred as class H. Class H amps are class AB amps with a modulated power supply to increase the efficiency. It was pioneered by Soundcraftsmen.

Steven

 

[thanh]

oh! sorry to my english!
Have you build any class H/G amp with discrete transistors?

 

[thanh]

My version IE is 5.00 so i can't view image. Can you post it up to here?Thanks a lot!

 

[Steven]

4,115,739

First page:

 

[thanh]

Thanks Steven! And the second stage?

 

[Steven]

Hi thanh,

I think the first page already says it all. Anyway the whole patent is 15 pages, too many to put on this forum while it is readily available from the patent website.
You said you had trouble with the Alternatiff viewer on IE5.0. I suggest you upgrade to IE6 or I can give you the link to the European patent office. These Swiss guys store everything in pdf format. So if you have Acrobat, go ahead.

http://gb.espacenet.com/espacenet/gb/en/e_net.htm
for the search page. Make sure to enter USA patents with US in front of the number and no commas, otherwise it cannot find it. So, in this case: US4115739 Then follow the 'Requested patent' link. It's a pity it shows the pdf's only page for page.

Steven