Life of KT150 tubes on ARC Amps


I have Audio Research 250SE amps and the tubes in it have 2400 Hours. I wanted to hear experience from other ARC users if they replaced KT150 tubes before 3000 Hours.  I am not sure if i need to replace them now or wait for some more time.   I dont have new set of tubes for me to compare with my current tubes and wanted to hear from other people who replaced the tubes.

veerapaneni
Average life for power tubes is 1500 to 2000 hours.

From Audio research:

Power Amplifier

Output tubes last up to 2,000 hours.
Note: Near the end of the tubes sonic life, aging vacuum tubes may degrade the sonic character of the product(s) they are used in. Make sure to replace your tubes before outright failure occurs. We stock vacuum tubes and match sets to the specification on each model. Audio Research tubes undergo thorough testing prior to being selected for use in our equipment. To order replacement tubes please contact your local dealer or send us a message at [email protected] for pricing information.
http://www.audioresearch.com/ContentsFiles/FAQs_April_2018_rev3.pdf


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That’s one reason I wouldn’t go back to a tube amp.  I listen at least 8 hours a day, every day (retired) and that would be 2 full sets of KT150 tubes a year which equates to over a thousand dollars!  It’s a good way to go broke fast.  
@ stereo5   

At $22,000 each I would be willing to bet a $1000 a year is pocket change.
Jim


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I had a pair of KT120s last around 2 years of daily listening (amp on 8 hours maybe every day I'm around) to a Jolida 502p...I recently replaced a pair of KT77s in my current Dennis Had SE amp as one of the tubes stopped working...lit up, looked fine, no sound...damn...the good news is the amp only uses 4 tubes total, and one's a rectifier...smaller amps will bind you to efficient speakers, but otherwise assuage any concerns about tube cost being a big deal...ARC's tube wear seems extreme but maybe they drive tubes harder or something...are the new Carver claims of very long (five year warranty includes tubes) tube life an actual thing? 
It costs $4000 if I have to retube with ARC tubes and around $2000 if I buy from third party sellers. That is for every 2000 hours if they don't go bad before that. Might be I need to look for SS amps in the long run. 
Dave Gordon on KT 150s:
"Quoted specs for the amps have not changed. Although we could change some of the operating voltages and get higher rated power output," says Dave Gordon of Audio Research, "we are going the conservative route, which we think will provide greater reliability and tube life. We expect owners to get 3000 hours out of these tubes, about 50% longer than KT120-equipped amps."

Quote from my Ref 160M manual which is also available on line at the ARC website:
"A Note about Vacuum Tubes Life Expectancy The vacuum tubes in your Reference 160M have been burned in, tested and electrically matched to provide the best performance and reliability of your amplifier. That said, vacuum tubes must be replaced from time to time. The KT150 output tubes in the Reference 160M should have an expected life of approximately 3,000 hours, while the smaller 6H30 tubes should have a life expectancy of approximately 4,000 hours. These life expectancies are only approximate."

I’m surprised that the ARC website now contains a general statement about tube hours which does not distinguish between KT120s and KT150s as the website used to do. I think this was an inadvertent failure.


@jea48................

just because the amps are 22K each doesn’t mean the guy is rich.  For all I know, he could have taken a home equity loan on them.  It is a lot of money for anyone to own those amps and have to retube  them every 2000 hours.  Most amps will do 3000 hours but I guess ARC drives their tubes harder than most. 
@jea48................

"just because the amps are 22K each doesn’t mean the guy is rich."

If he isn't rich he isn't the sharpest tool in the shed.
@ stereo5

Take at look at the OP’s 2ch system. I see $150K easy. Maybe not rich, but LOL, he sure ain’t poor.
Jim


Good catch jea48, I'm now thinking he is the sharpest tool in the shed.  But somehow retube costs of ARC amps is a familiar topic here.
jetter882 posts01-30-2019 7:11pm


But somehow retube costs of ARC amps is a familiar topic here.

Well thanks to gpgr4blu post, the KT150 tubes in the OP’s amps are good for up to 3000 hrs.


I read they are good for 3000 Hours but at 2400 hours they are not sounding that great and always played at very low volumes.  I am doubting the 3000 hours number now and that's why i posted this topic originally, to get other user opinions on the SE line Amps.
I got schooled pretty good.  Beautiful system, all top quality pieces.  My congratulations to the owner.
veerapaneni OP106 posts01-30-2019 7:32pm

I read they are good for 3000 Hours but at 2400 hours they are not sounding that great and always played at very low volumes.


From ARC Link.

Note: Near the end of the tubes sonic life, aging vacuum tubes may degrade the sonic character of the product(s) they are used in. Make sure to replace your tubes before outright failure occurs.

@ veerapaneni,

A very nice 2ch system indeed......

Cheers,  
Jim
If I ever had doubt about the value of tubes in my little single ended  power amp, I'd simply buy a Pass XA25 and call it a day. 
Definitely replace well before failure. There are many horror stories of the effects of tube failure in ARC amps. One of the best things about the VTLs I own is how well they handle tube flame outs, taking down a fuse only with lots of on board diagnostics to help you problem solve the issue

ive also found that pre amp tubes also need replacing well before rated life, they gradually go off and sound much more wooly, in my ARC phono and pre I found that even at 1500 hours they were markedly worse than a broken in new set
For the price of retubing a big amp directly from ARC, one can buy a used Music Reference RM-200 (100w/ch), which needs it's four output tubes (a pair of KT88 or 6550 per channel) replaced only every 10,000 hours. And like folkfreak's VTL, the MR tubes are fused, so no fireworks ;-) .
I dont own arc, but i know tube life in my amps can vary greatly if i dont keep an eye on the bias. 
bdp24, what do you do when you are not pimping for Roger? I mean really man, give it a break. It is tiresome. 
For the price of retubing a big amp directly from ARC, one can buy a used Music Reference RM-200 (100w/ch), which needs it's four output tubes (a pair of KT88 or 6550 per channel) replaced only every 10,000 hours. And like folkfreak's VTL, the MR tubes are fused, so no fireworks ;-) .
So you suggest I should of bought 5 Hyundai Santa Fe instead of my Porsche 911?   :-):-):-):-):-):-)
bdp24, what do you do when you are not pimping for Roger? I mean really man, give it a break. It is tiresome. 
Don't think you want to know.

I know man, Roger Modjeski and The Band, my two crusades. Also Bruce Thigpen and Iris Dement. I shall attempt to curb my enthusiasm out of consideration for ARC apologists, if for no other reason. Before I do though, I wonder how many have actually heard the RM-200 Mk.2 or Eminent Technology LFT-8b? Brooks Berdan enthusiastically recommended both to me, but that was on a friend-to-friend basis. To his paying customers he sold Jadis, VTL, and Wilson. WAY more money to be made selling brands with audiophile cache’ and bragging rights. Higher price = better sound? I have no doubt that lots of people dismissing the RM-200 Mk.2 (particularly in comparison to the REF 75SE/150SE) have never listened to the amp. They just "know".
Oh no, I forgot to mention one thing. Last one, I promise. Brooks wasn’t an ARC dealer (he had sold the brand when he was at GNP in Pasadena in the 80’s), but he loved having customers who owned them. He sold them a lot of RAM tubes, and also made money repairing them everytime a power tube took out some parts when it blew. The shelves of his used equipment racks were full of ARC power amps, everyone of them having scorched circuit boards. The brand reminds me of not Porsche, but Fiat ;-) .
Well, we have Iris Dement in common. Tis a shame she has put out so little music. It is no secret that ARC feels that fuses and other methods of circuit protection degrade the sound and also no secret that ARC's practice of having a single resistor act as circuit protection for tube failure is a pain for the customer. If a tube fails, the resistor not only needs to be replaced but on occasion there can be more damage to the circuit. For the most part, this is a thing of the past, but it was a huge problem back in the 90's. I don't think that there is anything magical about my Ref 150SE and I have no doubt that any number of competitor tube amps including the RM-200 equal or exceed it. I do believe that the ARC Ref 6 and Ref 10 preamps are among the best five preamps currently available. My Ref 6 makes me smile every time. Huge soundstage and a magical quiet forcefulness. I am one of those who believe the preamp is the single most important piece of electronics and is the heart of any system, more so than the amp or speaker. My choice of amp simply followed my choice of preamp. They match and are compatible though any number of other tube amps would also work well. 
@ veerapaneni

One thing you might want to check is the AC mains voltage at the outlet/s the amps are plugged into. The mains voltage can affect power tube life. Power tubes will last longer if the mains voltage is, say, 117Vac than if it is 123Vac. Check the mains voltage at the wall outlet/s with the amps powered on. Higher voltage increases the tube filament voltage as well as the DC power supply voltage.

Say the voltage measures 123Vac - 125Vac. You may very well be at the end of the tube life of the KT150 power tubes with 2400 hours on them.

Also worth noting, how often do you check the bias for the power tubes? Listening hours of use between checks....


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fsonicsmith322 posts02-01-2019 9:44am

It is no secret that ARC feels that fuses and other methods of circuit protection degrade the sound and also no secret that ARC’s practice of having a single resistor act as circuit protection for tube failure is a pain for the customer. If a tube fails, the resistor not only needs to be replaced but on occasion there can be more damage to the circuit.

Older ARC amps are not user friendly when it comes to biasing of the power tubes, that’s for sure.

As for the screen resistor that blows if the power tube runs away I find it hard to believe ARC didn’t know when the resistor blows, burns/blows apart, from being over loaded that ARC didn’t know the event could cause damage to a circuit trace.

It’s just common sense the resistor should not be installed close, tight, against a circuit trace on the circuit board. At the very least a fire rated insulator should have been installed between the resistor and the circuit trace to protect the trace from being damaged in the event the resistor blows, burns, explodes, apart. In fact the resistor should not be installed against the circuit board as it is. At the vary least it should be at minimum 1/8" from the board for even cooling around it. When you are pushing the amp, the tube, that resistor can/does get physically hot.


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I have get around 123 Volts and i bias my amps every few months.
I would be surprised if the KT-150s are worn out after 2400 hours. 3000 to 4000 hours may be a better point to pull and test.

If you are that concerned why not get them tested. I use KT-150s on a daily basis and have periodically tested them. Quite a ways from wear out.


From what I heard, ARC recommended tube hours is based on performance and not tube life.

I am very happy with my 75SE, which has been upgraded to SE status for at least 3 years. I haven't replaced the tubes and have no idea how many hours they have on the clock. I listen a lot to my Stax l700 ear speakers anyway, so don't believe I am over 2000 hours.

 I have to say that the numerous stories of damage when a tube blows, do concern me. Are there any other clues to near failure, such as wandering bias? It would be nice to change them just before one blows. My amp only has 4 tubes, but they are still costly when you have retired.


veerapaneni OP107 posts01-30-2019 7:32pm

I read they are good for 3000 Hours but at 2400 hours they are not sounding that great and always played at very low volumes. I am doubting the 3000 hours number now and that’s why i posted this topic originally, to get other user opinions on the SE line Amps.


I read they are good for 3000 Hours but at 2400 hours they are not sounding that great and always played at very low volumes.


"at 2400 hours they are not sounding that great"........

Time to replace the tubes!


At $44000 I would want the amps to sound their best. Period. No way in hell I would go over 3000 hrs. What do you think it will cost to send one or both amps back to ARC for repair if a tube/s shorts out and causes internal damage?


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I got around 3500 hours out of mine, but replacement was noticeably better (purchased from Kevin Deal). 


I have an ARC VT200 amp that I love(d) (with an ARC LS25 mk II preamp) - it sounds great - but the pain and expense of retubing it has become just too much for me. I just bought a pass labs X250.8 amp to replace the VT200. 
It's wasn't just the expense of retubing it - it's also 20 minutes it takes to warm up when wanting to listen to music - and the hassle of getting the amp to someone who can retube it for me. I once ordered the tubes myself to save money and one of the tubes arc-ed and i had to send it to get fixed anyway. 

I leave the pass amp on all the time and if i want to listen i just need to press PLAY on my CD player remote - I can play it whenever and not worry abt using up my tube life. 

The VT200 did sound great though :)

Steve