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32blownhemi

Tubes bad in 80 days on new Mc275? Are they BS'ing me?

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28 minutes ago, mike stehr said:

Gee, and I thought vacuum tubes were burned-in at the factory. 

Many tube vendors will burn in the tube prior to shipping to weed out some bad tubes.  I personal just warm the amp for a few minutes and play my music.  I don't push the amp hard in the first 1/2 hour or even after that since my normal listening level requires very little power.  I got this from the The Tubedepot:

 

The Benefits of Burn In Power Tubes

 

New tubes have always sounded and performed better when burned in prior to final testing and installation. By running a tube at full operating voltages (and not just the 6.3 heater voltages) for 24 hours, the cathode is allowed to stabilize and any oxide contaminants on the metal surfaces evaporate and are collected by the getter. The burned in tube is "cleaner" inside and better able to reproduce sound.

For burned in power tubes, the initial matching is less likely to drift and rebiasing isn't needed. The stability is immediately apparent. And for preamp tubes, the improved tone is instantaneously accessible without having to wait for the tube to stabilize making "tube rolling" much easier. And the combined benefit, the burn-in process quickly weeds out weak and suspect tubes before they get into your equipment.

If you want the best for your equipment and your listening enjoyment, burned in tubes are the most effective methods to insure your satisfaction. You don't have to wait for the best. https://www.tubedepot.com/the-benefits-of-burn-in-power-tubes

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38 minutes ago, mike stehr said:

Gee, and I thought vacuum tubes were burned-in at the factory. 

Gee, and never said they weren't.  Burned in, to me in my systems means installing, powering on, warming up, and checking for proper operation.  Leaving on for a few hours and making sure everything is OK.  That's all.

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Thanks everyone for all the replies! If he hasn't called the factory & gotten an approval for my repair to be free then I'll call Monday. Won't hurt anything.   Bill

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Update! I talked to McIntosh today & I'll find out tomorrow if they will cover the tubes. I must admit I'm impressed with their customer service. I wasn't impressed at first so here's the long story. I called & talked to the warrantee dept. The lady just said tubes aren't covered, period. I told her the story r/e 80 days of use, not even everyday & only 1-2 hours at a time. I told her where I bought it & she asked who repaired it. I said I didn't know. She said she was transferring me to another department. The answering machine picked up & I though. Oh great, she just got rid of me! So I called the place I bought it from & asked them who repaired it. I then called the warrantee dept back & before I could say anything the lady said. "I just called the place where they repaired it & I'm waiting for a call back". I asked her how she knew who repaired it & she just chuckled...  And while I was talking to her the department where I left the message at called me back! So even if they don't cover the tubes I'm impressed!     Bill

 

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I hope so, didn't get a chance to go get the amp today. Probably not tomorrow either. I live in Ventura, Calif. The town is on fire.  Although I don't think it could get to me...

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Stay safe. Although I personally wasn’t effected from the wine country fires I had many friends who were evacuated for a period of time and some did lose their homes. All I got was smoke. Your amp can wait!

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I think I'm safe from the fire. It's mostly in the mountains & I'm close to the beach. And I'm a prepper so I've got plenty of food, water, etc... I'd go there but the freeways are nuts... And I'm wondering with the electricity going on/off if it's not bad for my amp?   

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So did they pay for the tubes? I read this all the way to find out, but no finish here! I'd like to know. Lol

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I've had my share of Genelex KT88 with a short life in one of my MC275's.    I'm suspicious one of my amps does something to shorten their life.  Loud noise then fuse blows.

 

 

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1 hour ago, jwc said:

I've had my share of Genelex KT88 with a short life in one of my MC275's.    I'm suspicious one of my amps does something to shorten their life.  Loud noise then fuse blows.

 

 

 

Hey jc

 

Same tube location or channel pair of tubes going bad..?

 

If there are any intermittent solder connections in the bias circuit for the tube/tubes or parts having been damaged by a bad tube could lead to intermittent and/or early failures.

 

Turn the lights down very low or off and Inspect the tube plates for any that might exhibit a reddish plate condition that is noticeably different from the other tubes of the amp or in comparison to the other MC275 amps you own.  An abnormal cherry reddish plate indicates tube or more likely biasing issues. If you find a tube exhibiting this condition you can temporarily swap with another tube from a location that appears normal and note if the red plate condition follows the tube (indicating the tube itself is going bad) or causes the swapped good tube to start exhibiting a reddish plate condition (which would indicate bias or parts damaged supporting this tube location). 

 

miketn

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That's a good tip.  I'll try.  However, I have looked at the tubes before and not notice anything.  Then a sudden noise and then fuse blown.

 

I do have a little more trouble shooting to do before I call it an amp issue.

 

thanks

 

jc 

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I am surprised, however, that McIntosh ever let that tranny pass inspection before sending it out for sale. Unless the tranny had a delayed problem in the windings?

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McIntosh covers tubes for 90 days from the date of purchase, it's in black and white.

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On 11/28/2017 at 6:56 PM, 32blownhemi said:

It was 80 days from the day I bi-amped my Jubscala's with a second Mc275 to the day it quit working.

 

Well, apparently, one could go around the world in 80 days in 1872.

 

I used to have one 30 watt and one 40 watt McIntosh amp, used them heavily, and never changed a tube. 

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5 hours ago, dwilawyer said:

McIntosh covers tubes for 90 days from the date of purchase, it's in black and white.

 

Although true, anyone that purchases a tube amp should go into it with the understanding that tubes are consumables and an escrow account for replacements a necessity.  

 

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Folks complained when their new mustangs rear tire only yielded <9500 miles of service... Ford responded by instituting a prorated replacement program for original owners.

I said why the hell would I want another set of slippery Pirelli junk on my car and replaced my tread with the tires of my own choosing.

Thus ends the parable for today.p

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I probably already said it....I turn on dozens of tubes every day at my recording studio, most of them are tubes I put in equipment as I got it restored and online, most of it online 15+ years at this point.  Tubes that have died or been replaced for any reason?  Less the 6 probably.     The Fender Bassman I rebuilt in 1997 has EL34's in it....used Mullards that came out of a retired Altec PA amp.  That Fender was used for many years of rehearsals and gigs, still gets used in the studio regularly, same tubes.   Must have 40+ years on them.  

 

But a 90 day warranty on tubes is another thing, it speaks to the reliability of modern tubes.  

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4 hours ago, EMRR said:

I probably already said it....I turn on dozens of tubes every day at my recording studio, most of them are tubes I put in equipment as I got it restored and online, most of it online 15+ years at this point.  Tubes that have died or been replaced for any reason?  Less the 6 probably.     The Fender Bassman I rebuilt in 1997 has EL34's in it....used Mullards that came out of a retired Altec PA amp.  That Fender was used for many years of rehearsals and gigs, still gets used in the studio regularly, same tubes.   Must have 40+ years on them.  

 

But a 90 day warranty on tubes is another thing, it speaks to the reliability of modern tubes.  

 

I think I had EL34s in my 2 Dynaco 40 watt amps.  They lasted for the 10 years I had the amps, and for more years in the hands of the guy I sold them to.  The 12AX7/ECC83s in a Dyna preamp lasted just shy of 40 years, first with me, then with my department at SFSU...

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Reading this thread makes me feel fortunate. I've used new and NOS and pulled tubes over the years. I've lost one 6sn7, one 12ax7, and one bad 7F8. Not bad. 

 

My worse tube catastrophe was human error when Ryan Inman of HotGlassAudio (ripoffartist) sent my tubes back barely packed and broken 2 x smoke glass otiginal gec kt66, 2 x 5AR4, 2 x od3, and a 12ax7. All these tubes were nos from Brent Jesse.

 

 

 

 

 

 

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