Cello Amplifier Schematics

moray james · 11th April 2005, 01:09 AM

I have a buddy who has a cello amplifier which is doing some strange things. The amp seems to suffer a degridation of bass then midrange after it has run for several months. He first thought the problem was cable related but that does not seem to be the case. He is looking for assistance in trouble shooting the amp and wonders if there are any available schematics? He has tried several obvious sources including Mr. Levinson with no or little success. Any suggestions or directions any of you can suggest? Thanks for any help. Best regards Moray James.

tomtt · 11th April 2005, 01:31 AM

this might work
http://matthew-james.net/interview_6.cfm

jam · 11th April 2005, 04:25 AM

Moray,

Look for defective capacitors in the feedback loop, assuming the amp uses a capacitor in the feedback loop. They can dry out and change value and cause the problem you mention. This can be easily checked with a scope and squarewave generator or plotting frequency response with a good VOM.

Jam

moray james · 12th April 2005, 01:56 AM

Thank you for your assistance> I have passed along these letters to my buddy. Should anybody know where to find schematics that would be a real bonus. Regards Moray James.

ezmeralda11 · 12th April 2005, 02:31 AM

I thought viola labs (www.violalabs.com) had taken over for Cello. Maybe they can help. If not there should be someone out there who (can't recall who) can test/repair an amplifier of that caliber--its not like its an Adcom or anything cheap. Assuming you are wanting someone else to work on it.

analog_sa · 12th April 2005, 06:13 AM

Delegating these sort of repairs to a third party seems like an exceptionally bad idea. Are repairs really needed? Can the degradation be measured? If a problem really exists and it is common to both channels that only leaves common components. PS?

My guess is that's it's a severe case of audiophilia nervosa. The only good medicine is selling/incinerating the troubled device.

11th April 2005, 01:09 AM	#1
moray james diyAudio Member Join Date: Aug 2003 Location: Calgary on the Bow	Cello Amplifier Schematics I have a buddy who has a cello amplifier which is doing some strange things. The amp seems to suffer a degridation of bass then midrange after it has run for several months. He first thought the problem was cable related but that does not seem to be the case. He is looking for assistance in trouble shooting the amp and wonders if there are any available schematics? He has tried several obvious sources including Mr. Levinson with no or little success. Any suggestions or directions any of you can suggest? Thanks for any help. Best regards Moray James. __________________ moray james

11th April 2005, 01:31 AM	#2
tomtt diyAudio Member Join Date: Aug 2002 Location: kansas city mo, and on occasion, around the world ... Blog Entries: 15	cello this might work http://matthew-james.net/interview_6.cfm

12th April 2005, 01:56 AM	#4
moray james diyAudio Member Join Date: Aug 2003 Location: Calgary on the Bow	Thank you for your assistance> I have passed along these letters to my buddy. Should anybody know where to find schematics that would be a real bonus. Regards Moray James. __________________ moray james

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11th April 2005, 04:25 AM	#3
jam diyAudio Member Join Date: May 2001 Location: Charlotte,NC,USA	Moray, Look for defective capacitors in the feedback loop, assuming the amp uses a capacitor in the feedback loop. They can dry out and change value and cause the problem you mention. This can be easily checked with a scope and squarewave generator or plotting frequency response with a good VOM. Jam

12th April 2005, 02:31 AM	#5
ezmeralda11 diyAudio Member Join Date: Sep 2001	I thought viola labs (www.violalabs.com) had taken over for Cello. Maybe they can help. If not there should be someone out there who (can't recall who) can test/repair an amplifier of that caliber--its not like its an Adcom or anything cheap. Assuming you are wanting someone else to work on it.

12th April 2005, 06:13 AM	#6
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	Delegating these sort of repairs to a third party seems like an exceptionally bad idea. Are repairs really needed? Can the degradation be measured? If a problem really exists and it is common to both channels that only leaves common components. PS? My guess is that's it's a severe case of audiophilia nervosa. The only good medicine is selling/incinerating the troubled device.

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