Regarding Mcintosh MC275VI

MC275VI

New Member
I am new to the forum so please bear with me if I post a question that might have been up for topic in the past.

I have a set up consisting of a C2300 with a pair of MC275VI's used as mono blocks. Once in a while one of the amps go into red mode, meaning the tubes starts flashing red and shuts down into protective mode. I use good quality cables (mid level Nordost cables quality) and everything is to my knowledge hooked up correct. Once I restart the amp it's all fine. I am quite new to tubes (only had this set up for 6 months...) so any input would be much appreciated. Thank you
 
I am not familiar with the model but, looking at McIntosh literature, it sounds like the amp's Sentry Monitor is activating. This monitor is to protect the amp from damage in situations where high current levels could occur in the output, for example, an output tube is defective or there is an overload situation due to the speakers from impedance mismatch, etc. According to the McIntosh literature if, for example, it is a failing output tube, the small signal tubes next to the affected channel will change color to glow red, indicating the channel with the issue.

If this is what is happening, I would not continue to keep restarting the amp without first scoping out the cause and resolving any issue.

Many members in this Tube forum are knowledgeable on McIntosh gear, in addition to deep knowledge on many things tube related. Additionally, there is a McIntosh forum here on AK, which focuses only on McIntosh equipment. The members there could likely help you with this model if you find you are not getting the needed response from this forum. This thread can be later moved over to the McIntosh forum if you request.
 
I am not familiar with the model but, looking at McIntosh literature, it sounds like the amp's Sentry Monitor is activating. This monitor is to protect the amp from damage in situations where high current levels could occur in the output, for example, an output tube is defective or there is an overload situation due to the speakers from impedance mismatch, etc. According to the McIntosh literature if, for example, it is a failing output tube, the small signal tubes next to the affected channel will change color to glow red, indicating the channel with the issue.

If this is what is happening, I would not continue to keep restarting the amp without first scoping out the cause and resolving any issue.

Many members in this Tube forum are knowledgeable on McIntosh gear, in addition to deep knowledge on many things tube related. Additionally, there is a McIntosh forum here on AK, which focuses only on McIntosh equipment. The members there could likely help you with this model if you find you are not getting the needed response from this forum. This thread can be later moved over to the McIntosh forum if you request.
OK thank you for the input,. The amps are almost brand new and so are the tubes... Will contact my local dealer and maybe have the amp serviced.
 
I am not familiar with the model but, looking at McIntosh literature, it sounds like the amp's Sentry Monitor is activating. This monitor is to protect the amp from damage in situations where high current levels could occur in the output, for example, an output tube is defective or there is an overload situation due to the speakers from impedance mismatch, etc. According to the McIntosh literature if, for example, it is a failing output tube, the small signal tubes next to the affected channel will change color to glow red, indicating the channel with the issue.

If this is what is happening, I would not continue to keep restarting the amp without first scoping out the cause and resolving any issue.

Many members in this Tube forum are knowledgeable on McIntosh gear, in addition to deep knowledge on many things tube related. Additionally, there is a McIntosh forum here on AK, which focuses only on McIntosh equipment. The members there could likely help you with this model if you find you are not getting the needed response from this forum. This thread can be later moved over to the McIntosh forum if you request.
How do I move this thread to the mcintosh ?
 
I am not familiar with the model but, looking at McIntosh literature, it sounds like the amp's Sentry Monitor is activating. This monitor is to protect the amp from damage in situations where high current levels could occur in the output, for example, an output tube is defective or there is an overload situation due to the speakers from impedance mismatch, etc. According to the McIntosh literature if, for example, it is a failing output tube, the small signal tubes next to the affected channel will change color to glow red, indicating the channel with the issue.

OK thank you for the input,. The amps are almost brand new and so are the tubes... Will contact my local dealer and maybe have the amp serviced.

What Tinkerbelle said above is all correct. I have the same setup as you using two 275s as mono blocks. I always had one of them that seemed to be weaker and trip just like yours. I kinda put it off and figured it was the speakers tripping it because it would always work again after reseting it. But after a while It got worse till one day I couldn't reset it. Lucky me because one more month it would have went out of warranty. I brought it in and it got serviced and I haven't had a problem since. The tech said it was a loose solder joint, don't know if he was just feeding me a line or not but thats the info I got.

So my advice is to bring it in to a local authorized mac shop with you receipt and they will take care of everything with McIntosh. If it's under three years old it will cost you nothing, and you have 90 days on the tubes if one is bad.
Welcome to AK and the mac forum

BTW tell us what speakers you are using? their ohm? and what taps you are using on the amps?
 
I am new to the forum so please bear with me if I post a question that might have been up for topic in the past.

I have a set up consisting of a C2300 with a pair of MC275VI's used as mono blocks. Once in a while one of the amps go into red mode, meaning the tubes starts flashing red and shuts down into protective mode. I use good quality cables (mid level Nordost cables quality) and everything is to my knowledge hooked up correct. Once I restart the amp it's all fine. I am quite new to tubes (only had this set up for 6 months...) so any input would be much appreciated. Thank you

Hi...

You don't indicate whether the output tubes are glowing red or is it the LEDs under the smaller tubes?

Mark - McIntosh Service Center
 
Check the ohm'age of your speakers. I had this same exact problem when I hooked 16 ohm speakers to the 8 ohm taps on the MC-275 Mark VI....
 
post: 10883766 said:
Check the ohm'age of your speakers. I had this same exact problem when I hooked 16 ohm speakers to the 8 ohm taps on the MC-275 Mark VI....

You mean 8 ohm speakers at the 16 ohm taps?
 
You mean 8 ohm speakers at the 16 ohm taps?
No, as ridiculous as it seems, I mistakenly hooked my 16 ohm speakers to the 8 ohm taps (in non-bridged stereo mode) and the protection circuit engaged on the right channel. Once I hooked the speakers to the 16 ohm taps, everything worked perfectly....
 
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Now you know why I swore off tubes when I had my pair of 275 Mk I's in the late 60's and early 70's. And we had good tubes back then. I guaranteee, a MC152 will run circles around two 275's.
 
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