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Replacing a Genelax KT 88 Tube


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Hi. I bought 8 above tubes for my Audio Research VT100 from the US and they have max 100 hours. They came biased. One of the tubes has blown. How do I get a replacement wirh same bias but not having to go back to vendor in the US.

 

Thanks

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  Amplifiers using fixed bias require  adjustment of the cathode current when replacing output valves. The owners manual should  tell you if can be performed by a user or if it should be performed by a technician.  

Edited by VanArn
typo
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As mentioned above the valves do not come pre-biased. Biasing can only be done on the particular amp you are using the tubes with. Biasing on your amp needs to be done when you change tubes. if this is not done the tubes may not last as long as they would have with biasing and your amp may not operate optimally. So, was the amp biased after the tubes were replaced, and how long ago were the tubes replaced?

Tubes with "only 100 hours" bought from overseas can mean anything and many people are duped by unscrupulous sellers. Are they vintage valves or new production valves?

 

Read this http://www.audioresearch.com/ContentsFiles/VT100 MKII_BiasAdjust.pdf 

if it makes no sense to you you will need a tech. If you want to match the valves you have you will need to get them tested on the same model of calibrated machine the seller you buy from uses as different testers give different results.

 

These are a few things to consider...

 

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Experienced technicians do not use  emission valve testers.   A high power valve amplifier should provide independent adjustment of fixed bias to each valve and also a means of adjusting the push pull balance. This is because valves cannot be relied on to age equally despite being matched  by  some sort of valve test.

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1 hour ago, dsj1188 said:

Afer I bought them I has Eddie Lee biased them for me in 2013. I had them for 2 years with little use and then had it stored until now when 1 blew up.  I will try and contact him again to source and fix it for me.

You’ll need to look up what “biasing” refers to, as mentioned by members here.  

Perhaps have a read here:

 

https://wallofsound.ca/audioreviews/amplification/output-tube-biasing-an-introduction/

 

 

 

 

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