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 Post subject: Tube Gear Sanity Check
PostPosted: Sat May 06, 2017 7:02 am 
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HI;
I need a sanity check, and some advice from the experienced CAM user-group. I've recently had my McIntosh 275 repaired. According to the service technician, the issue was a bad "aftermarket" KT-88 tube where "one pin was too long" (and caused internal damage to the tube socket).

The bad tube was not returned and can't "eyeball". Service technician recommended I buy McIntosh tubes only.

Any merit to this? Anybody with similar experience? Comments welcomed. I have doubts, but wanted to check with the CAM community before I order replacement tubes.

I appreciate all replies.


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PostPosted: Sat May 06, 2017 7:19 am 
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I know for a fact that only JJ tubes should be used in JJ amps...others can cause damage due to biasing issues...it happened to me!!! :(

So when the technician suggests you stick with McIntosh Tubes for a McIntosh amp then, yes, I think it has merit.

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PostPosted: Sat May 06, 2017 7:43 am 
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Voodoo Funk wrote:
I know for a fact that only JJ tubes should be used in JJ amps...others can cause damage due to biasing issues...it happened to me!!! :(

So when the technician suggests you stick with McIntosh Tubes for a McIntosh amp then, yes, I think it has merit.



Interesting comment. How does ones amp know which brand of tube is being used?


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PostPosted: Sat May 06, 2017 7:46 am 
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BinkyTheCat wrote:
Voodoo Funk wrote:
I know for a fact that only JJ tubes should be used in JJ amps...others can cause damage due to biasing issues...it happened to me!!! :(

So when the technician suggests you stick with McIntosh Tubes for a McIntosh amp then, yes, I think it has merit.



Interesting comment. How does ones amp know which brand of tube is being used?


I was a bit incredulous at first myself...but according to Claudio, the biasing on the JJ amps are specifically tuned for the JJ 300B tube and any other tube can cause damage.

Good way to sell your tubes!!! :lol:

KR Tube amps are the same...you can only use KR tubes in them because of the high plate current.

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PostPosted: Sat May 06, 2017 8:04 am 
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Another bit of enlightenment.

I wonder if the reverse is true?? JJ or KR tubes causing damage to dissimilar branded components?

Never heard of that occurring...


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PostPosted: Sat May 06, 2017 8:06 am 
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Hi,

Duh! Be careful. It could be true that one KT88 in the amp had a longer than normal tube pin. But, unless it was 'very long', it would just stick out a little bit from the bottom of the tube socket. It would be unlikely to cause any actual damage. And even if the tube socket were damaged, tube sockets are, at most, $5 items and easily replaced by any competent repair person.

Audio sales and repair people like to 'black box' clients with all kinds of fake mumbo-jumbo because they assume you don't know the score and that you want the best for your treasures, which you do. Aggressive Canadian Tire car repair shops do the same thing by up-selling all sorts of repair and parts stuff to people that they don't actually need. They secondarily reward their repair people by giving them a parts sales commission and by essentially lying to clients.

Any KT88s will work in your amp. Tube amps are very sturdy creatures and as long as the output tube bias is adjusted within a certain specified range, they will happily sing for you for years.

Your instinct is that this might be a scam. Trust that instinct. I took a Dyna Stereo 70 that I had very carefully built myself into a shop in Ottawa many years ago because there was a problem with the power supply. They called me and I went to pick it up. The bill was $500 and this was in 1982. Then they had to retrieve it from their 'listening room' because they had hooked it up and were using it for demos of speakers they were selling. Nice touch. We finally got it onto the front counter and I paid the bill and then the shop owner delivered the 'coup de grace'. He looked at me with a downward pointing head and grave eyes and told me in the most serious tones possible that the amp needed to be completely rebuilt because someone had used acid core solder when it was assembled. I just laughed at him and walked out and never went back. A decade later that same shop owner was running a XXX Video store in the west end of Ottawa.

Cheers,
David Neice

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PostPosted: Sat May 06, 2017 8:07 am 
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BinkyTheCat wrote:
Another bit of enlightenment.

I wonder if the reverse is true?? JJ or KR tubes causing damage to dissimilar branded components?

Never heard of that occurring...


I worded my original statement wrong...causes damage to the tubes!!

My bad!!! :oops:

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PostPosted: Sat May 06, 2017 8:08 am 
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I could be wrong but don't think McIntosh made tubes in the 60's anyways sounds like malarkey to me! :o


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PostPosted: Sat May 06, 2017 8:09 am 
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buybye88 wrote:
Hi,

Duh! Be careful. It could be true that one KT88 in the amp had a longer than normal tube pin. But, unless it was 'very long', it would just stick out a little bit from the bottom of the tube socket. It would be unlikely to cause any actual damage. And even if the tube socket were damaged, tube sockets are, at most, $5 items and easily replaced by any competent repair person.

Audio sales and repair people like to 'black box' clients with all kinds of fake mumbo-jumbo because they assume you don't know the score and that you want the best for your treasures, which you do. Aggressive Canadian Tire car repair shops do the same thing by up-selling all sorts of repair and parts stuff to people that they don't actually need. They secondarily reward their repair people by giving them a parts sales commission and by essentially lying to clients.

Any KT88s will work in your amp. Tube amps are very sturdy creatures and as long as the output tube bias is adjusted within a certain specified range, they will happily sing for you for years.

Your instinct is that this might be a scam. Trust that instinct. I took a Dyna Stereo 70 that I had very carefully built myself into a shop in Ottawa many years ago because there was a problem with the power supply. They called me and I went to pick it up. The bill was $500 and this was in 1982. Then they had to retrieve it from their 'listening room' because they had hooked it up and were using it for demos of speakers they were selling. Nice touch. We finally got it onto the front counter and I paid the bill and then the shop owner delivered the 'coup de grace'. He looked at me with a downward pointing head and grave eyes and told me in the most serious tones possible that the amp needed to be completely rebuilt because someone had used acid core solder when it was assembled. I just laughed at him and walked out and never went back. A decade later that same shop owner was running a XXX Video store in the west end of Ottawa.

Cheers,
David Neice


Nice to know there is life after audio!!! :lol:

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PostPosted: Sat May 06, 2017 9:06 am 
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I'm sceptical, who makes McIntosh tubes? sure as **** not McIntosh.
Like AR saying you have to use their tubes..bought through them.
About KR, I'm under the impression you can run their 300b type tubes in a normal amp but they use a higher current on the heater, and will take a higher plate voltage..might not perform as well?..I guess the heater current capabilities of the amp might be important.


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PostPosted: Sat May 06, 2017 9:08 am 
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vonclod wrote:
I'm sceptical, who makes McIntosh tubes? sure as **** not McIntosh.
Like AR saying you have to use their tubes..bought through them.
About KR, I'm under the impression you can run their 300b type tubes in a normal amp but they use a higher current on the heater, and will take a higher plate voltage..might not perform as well?..I guess the heater current capabilities of the amp might be important.


Please define a 'normal amp'???

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PostPosted: Sat May 06, 2017 9:17 am 
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Voodoo Funk wrote:
vonclod wrote:
I'm sceptical, who makes McIntosh tubes? sure as **** not McIntosh.
Like AR saying you have to use their tubes..bought through them.
About KR, I'm under the impression you can run their 300b type tubes in a normal amp but they use a higher current on the heater, and will take a higher plate voltage..might not perform as well?..I guess the heater current capabilities of the amp might be important.


Please define a 'normal amp'???


Think he is referring to amps that don't exaggerate plate voltage and heater current.


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PostPosted: Sat May 06, 2017 9:19 am 
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BinkyTheCat wrote:
Voodoo Funk wrote:
vonclod wrote:
I'm sceptical, who makes McIntosh tubes? sure as **** not McIntosh.
Like AR saying you have to use their tubes..bought through them.
About KR, I'm under the impression you can run their 300b type tubes in a normal amp but they use a higher current on the heater, and will take a higher plate voltage..might not perform as well?..I guess the heater current capabilities of the amp might be important.


Please define a 'normal amp'???


Think he is referring to amps that don't exaggerate plate voltage and heater current.


I'll accept that!!! :lol:

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PostPosted: Sat May 06, 2017 9:22 am 
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Voodoo Funk wrote:
vonclod wrote:
I'm sceptical, who makes McIntosh tubes? sure as **** not McIntosh.
Like AR saying you have to use their tubes..bought through them.
About KR, I'm under the impression you can run their 300b type tubes in a normal amp but they use a higher current on the heater, and will take a higher plate voltage..might not perform as well?..I guess the heater current capabilities of the amp might be important.


Please define a 'normal amp'???

Not a KR amp :)


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PostPosted: Sat May 06, 2017 9:24 am 
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vonclod wrote:
Voodoo Funk wrote:
vonclod wrote:
I'm sceptical, who makes McIntosh tubes? sure as **** not McIntosh.
Like AR saying you have to use their tubes..bought through them.
About KR, I'm under the impression you can run their 300b type tubes in a normal amp but they use a higher current on the heater, and will take a higher plate voltage..might not perform as well?..I guess the heater current capabilities of the amp might be important.


Please define a 'normal amp'???

Not a KR amp :)


It's what makes it 'special'... :idea:

Lamborghini is not a 'normal' car!!! :lol:

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