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PostPosted: 20 Sep 2008, 14:49 
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What do you think the high frequency problem is? It could be a limitation of the output iron. Have you checked for ringing and overshoot?

Cheers

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PostPosted: 21 Sep 2008, 07:42 
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Gio wrote:
What do you think the high frequency problem is? It could be a limitation of the output iron. Have you checked for ringing and overshoot?

Hi Gio!
I havent checked as I havent got a scope. I need one fast, but prices here are insane, and I just cant afford it.
I contacted Bruce and he told me that in his opinion this amp might need some NFB to clean the top end.

I think I'll have to get one one of those USB scopes from US.

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PostPosted: 21 Sep 2008, 10:10 
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Hi Bernardo,

The DSO-2150 USB PC Based Oscilloscope that I got from China on eBay works really well and was very nicely priced.

Some NFB should reduce the distortion. Here are a couple of excellent articles that looks at different output transformers and feedback:

http://www.tubelab.com/BudgetOPT.htm
http://www.tubelab.com/Output_Transformers.htm

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PostPosted: 22 Sep 2008, 20:31 
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Gio wrote:
The DSO-2150 USB PC Based Oscilloscope that I got from China on eBay works really well and was very nicely priced.

Some NFB should reduce the distortion. Here are a couple of excellent articles that looks at different output transformers and feedback:

http://www.tubelab.com/BudgetOPT.htm
http://www.tubelab.com/Output_Transformers.htm

Great links Gio!!! Thank you very much, really nice.

Me and Bruce are trying to work out on a fix for my SE KT88 amp distortion. He believes it might be a transient intermodulation distortion problem.

Alex, do you get that on your amp?

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PostPosted: 27 Sep 2008, 00:50 
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bsgd wrote:
Me and Bruce are trying to work out on a fix for my SE KT88 amp distortion. He believes it might be a transient intermodulation distortion problem.

Alex, do you get that on your amp?


I can't check right now, my amp is doing the rounds around the country, being auditioned by friends.

I can't seem to remember having that problem. I bypassed my coupling cap with a 0.1uf MKP and it seem to help the top end a lot.


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PostPosted: 27 Sep 2008, 05:47 
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Well I'll try that too. I dont think thats whats causing my problem, but anyway if it helps the top end, then I've gotta try it!

I also finally got a scope. It will take sometime before it gets here, but I'll be able to test the amp and check if somethign is wrong.

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PostPosted: 27 Sep 2008, 11:53 
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Hi Bernardo.

A scope is very handy. What type did you get? Oh yeah, after you get a scope you will find that a signal generator comes in handy!

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PostPosted: 05 Apr 2010, 15:14 
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I'm trying to build a similar design and I have a (stupid) question: What did you do with pin 9 from 6N1P? Did you connected to ground or left it unconnected?

Thanks,
alecu7


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PostPosted: 05 Apr 2010, 18:36 
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I would ground it at the same grounding point used for the grid and cathode.

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PostPosted: 06 Apr 2010, 06:49 
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Is it better to use one tube 6n1p for each channel or it's ok to use one tube for both? I'm worry about channel separation.

Thanks,
Alecu7


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