Amp problems, suggestions needed :(

fedx · 20th October 2005, 08:48 PM

Hello, i have built an amplifier wich use a tip 142 & tip 147 as output transistors, this is my first homebrew amplifier, i choosed it for its simplicity.
It works, but i dont think its doing very well, at low volume its sound distorted, but at mid to hight volume the distortion seems to dissapears (or i can't notice it).

Anyone have some suggestions of what can be wrong?(or maybe its normal?) or any improvements for the circuit?
thanks in advance, any ideas would be appreciated.

Here is the link of the web page were i found the schematic:
http://europa.spaceports.com/~fishbake/amp/ca100.htm
Thanks.

darkfenriz · 20th October 2005, 08:56 PM

Add third diode in chain and 47pF cap between base and collector of tip41

fedx · 21st October 2005, 03:13 AM

Thanks very much for the suggestion, later i will try the mod.

audio3000 · 21st October 2005, 03:38 AM

It's very likely the amp is suffered from cross-over distortion. There's only 2 diodes to bias the 4 diodes in TIP124 and 127 in the circuit. Adding just one more diode as suggested above may not fix your problem completely. On paper, 4 are needed. But make sure you watch the bias current when you play with the bias. The bias current should be somewhere between 40 to 100 mA as a beginning.

Good luck.

20th October 2005, 08:48 PM	#1
fedx diyAudio Member Join Date: Oct 2005	Amp problems, suggestions needed :( Hello, i have built an amplifier wich use a tip 142 & tip 147 as output transistors, this is my first homebrew amplifier, i choosed it for its simplicity. It works, but i dont think its doing very well, at low volume its sound distorted, but at mid to hight volume the distortion seems to dissapears (or i can't notice it). Anyone have some suggestions of what can be wrong?(or maybe its normal?) or any improvements for the circuit? thanks in advance, any ideas would be appreciated. Here is the link of the web page were i found the schematic: http://europa.spaceports.com/~fishbake/amp/ca100.htm Thanks.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Suggestions on OB problems	maoumaou	Multi-Way	13	29th February 2008 02:35 AM
your suggestions needed	saltyreefguy	Car Audio	4	24th June 2006 06:23 PM
Amp suggestions needed	1108	Tubes / Valves	6	26th July 2005 08:15 PM
suggestions needed for HT	googleguy	Multi-Way	0	26th November 2003 08:03 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

20th October 2005, 08:56 PM	#2
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	Add third diode in chain and 47pF cap between base and collector of tip41

21st October 2005, 03:13 AM	#3
fedx diyAudio Member Join Date: Oct 2005	Thanks very much for the suggestion, later i will try the mod.

21st October 2005, 03:38 AM	#4
audio3000 diyAudio Member Join Date: Jun 2005 Location: Canada	It's very likely the amp is suffered from cross-over distortion. There's only 2 diodes to bias the 4 diodes in TIP124 and 127 in the circuit. Adding just one more diode as suggested above may not fix your problem completely. On paper, 4 are needed. But make sure you watch the bias current when you play with the bias. The bias current should be somewhere between 40 to 100 mA as a beginning. Good luck.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)