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Old 23rd March 2012, 04:06 AM   #191
taj is offline taj
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Quote:
Originally Posted by biju55 View Post
what is the maximum life of a tube amplifier ?
If you change the oil and spark plugs regularly and keep it tuned up, you should be able to keep it running for about 1 million kilometres.
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Old 23rd March 2012, 04:22 AM   #192
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Originally Posted by coffeedj View Post
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Note: This is not necessarily true for circuit board based tube amplifiers. Traces lift, the material degrades and starts conducting, audio sound gets worse and worse, and eventually it is trash. Point-to-point is what lasts.
Hmm... While I don't necessarily disagree that point to point is probably better in the long run, especially better than PCBs without solder masks, but I have plenty of first generation PCB based amplifiers, and none have lifting traces, nor degrading/conducting materials, and they certainly don't sound like trash, or even worse than I remember they did decades ago.

I suspect your scenario assumes very poorly treated (dirty, mishandled) or poorly designed (burnt areas) products.

Last edited by taj; 23rd March 2012 at 04:28 AM.
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Old 29th March 2012, 01:46 PM   #193
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regarding safety....there is a small capacitor on switching the amp on & off.This are MPX 2X capacitors for EMI surpression and this small thing is saving other capacitors and semicondactors in the amp and all equipement conected with the amp from dangerous overvoltage spikes caused by sparks when switching amp on and off...the question is..does anybody knows can I use a biger capacitance ( the original has value of 0.01mf) or can I use even 0.1 mf instead ?
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Old 29th March 2012, 05:42 PM   #194
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I typically use .1uF x 630V, and have seen even .22uF used. However, I'm not sure if there is any real advantage in going larger.

On a related note: Most important is the quality of the switch. Even a small amount of residual resistance can cause high frequency EMI.
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Old 29th March 2012, 07:10 PM   #195
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Quote:
Originally Posted by coffeedj View Post
I typically use .1uF x 630V, and have seen even .22uF used. However, I'm not sure if there is any real advantage in going larger.

On a related note: Most important is the quality of the switch. Even a small amount of residual resistance can cause high frequency EMI.
Thanks....only I use 275 v as I found this value in the amp...and..so true..the quality of the switch is very important..this EMI values can rise to more then 6 KV and damage all capacitors - from electrolitics to blocks in a sgnal path..this damages are very special as all capaciots are showing nominal values but once you put signal throug them you have very unpleasant highs,no deep bas and the sound is just to loud....only cheramic capacitors are less sensitive on this EMI
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Old 21st May 2012, 06:17 AM   #196
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any resource book about Output Transformer design and calculation better than Robert G. Wolpert's book?
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Old 11th July 2012, 01:53 PM   #197
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Can anyone direct me to a link that will help me understand the cathode follower application in what I believe is a AB1 mono block amp! There are two 6L6's paralleled! Just want to learn!!!
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Old 16th September 2012, 01:35 AM   #198
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simak...
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Old 21st December 2012, 05:59 AM   #199
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Can someone help? Can four IN4007 full bridge be replaced with a KGU8M?
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Old 30th December 2012, 06:24 PM   #200
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for what voltages/current are you tring to swap the diodes?
you can use:
db107 , 2w10 , kbl410 , pbu1010 , kbpc1010 , kbpc610 all can withstand 1kV and almost 1 amp

Last edited by maton00; 30th December 2012 at 06:35 PM.
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