bias amp while hot or cold?

nicksmurf · 26th June 2003, 02:10 AM

Should I bias my amp while it is cold, or after it warms up to normal operating temp? Since I guess the bias current seems to rise with the temperature. Whatever I do I'm replacing the pots first.

- Nick

jam · 26th June 2003, 02:21 AM

After half an hour to an hour.

nicksmurf · 26th June 2003, 02:31 AM

Thanks, i wasn't sure.

sam9 · 26th June 2003, 03:26 AM

Some recomend connecting an input signal and a load (speaker or dummy) and running ithat way until the temperature stabilizes. Then disconect the signal and load and set the bias before it cools.

hugobross · 26th June 2003, 08:50 AM

After having set up the bias check again after a while!

Repeat this several times.

peranders · 28th June 2003, 07:56 AM

Good idea to really make the amp hot, either by turning up bias (if it's possible) or by high output power. When it's really hot, adjust the bias. Then in cooling process, measure the bias at a few temperatures so you see that it's rather stable or the bias increases slightly with lower temperature. If this is the case the amp will be 100% regarding to bias. It's important that all parts inside have reach stable temperature and this can take 15-30 minutes at least if you include transformers and all big parts.

26th June 2003, 02:10 AM	#1
nicksmurf diyAudio Member Join Date: May 2003 Location: Cleveland Ohio	bias amp while hot or cold? Should I bias my amp while it is cold, or after it warms up to normal operating temp? Since I guess the bias current seems to rise with the temperature. Whatever I do I'm replacing the pots first. - Nick

28th June 2003, 07:56 AM	#6
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	Good idea to really make the amp hot, either by turning up bias (if it's possible) or by high output power. When it's really hot, adjust the bias. Then in cooling process, measure the bias at a few temperatures so you see that it's rather stable or the bias increases slightly with lower temperature. If this is the case the amp will be 100% regarding to bias. It's important that all parts inside have reach stable temperature and this can take 15-30 minutes at least if you include transformers and all big parts. __________________ /Per-Anders (my first name) or P-A as my friends call me

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26th June 2003, 02:21 AM	#2
jam diyAudio Member Join Date: May 2001 Location: Charlotte,NC,USA	After half an hour to an hour.

26th June 2003, 02:31 AM	#3
nicksmurf diyAudio Member Join Date: May 2003 Location: Cleveland Ohio	Thanks, i wasn't sure.

26th June 2003, 03:26 AM	#4
sam9 diyAudio Member Join Date: Jun 2002 Location: Left Coast	Some recomend connecting an input signal and a load (speaker or dummy) and running ithat way until the temperature stabilizes. Then disconect the signal and load and set the bias before it cools.

26th June 2003, 08:50 AM	#5
hugobross diyAudio Member Join Date: Jun 2001 Location: Flanders, Belgium	After having set up the bias check again after a while! Repeat this several times.

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