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Old 14th June 2011, 05:51 PM   #31
Jeb-D. is offline Jeb-D.  United States
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[QUOTE=kevinkr;2604683]Like CC they do have a significant voltage coefficient QUOTE]
Hey Kevin,
I've suspected this, but never tested. I have a 120V variable DC benchtop supply. Perhaps I'll plot some charts when I get a chance.
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Old 15th June 2011, 10:32 AM   #32
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I'd put the Jensens back in, bypass them with a .1uf poly cap, if you have a cement resistor on your power output, change it with a non inductive resistor like is in speaker crossovers.

also, consider your input impedance. calculations worry about bias more than the input load. Start the grid to ground resistor at 1M and go down till the phasey sound is eliminated in the sound stage. you'll notice a gain increase as you reach the proper input impedance and as the total circuit becomes resonate, the white noise will go down.

I never liked any Russian caps as they are not consistent in quality ( esr fluctuates too much from cap to cap)
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Old 30th June 2011, 05:21 PM   #33
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update: I'm making the schematics as we speak, will be done within 2 weeks or 2 months
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Old 30th June 2011, 05:28 PM   #34
kevinkr is offline kevinkr  United States
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Quote:
Originally Posted by DavesNotHere View Post
<snip>

I never liked any Russian caps as they are not consistent in quality ( esr fluctuates too much from cap to cap)
Just curious as to whether you have tried or measured the Russian FT-3? They seem very consistent in terms of tolerance and all other parameters I have measured. I have not measured their ESR, but would expect similar behavior.

I find the Jensens to be very colored, but that is just my set of preferences.
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Old 30th June 2011, 05:29 PM   #35
kevinkr is offline kevinkr  United States
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Originally Posted by jasonthegreat View Post
update: I'm making the schematics as we speak, will be done within 2 weeks or 2 months
Carry on at whatever pace you can manage!
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Old 30th June 2011, 08:50 PM   #36
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Quote:
Originally Posted by DavesNotHere View Post
I never liked any Russian caps as they are not consistent in quality ( esr fluctuates too much from cap to cap)


Hmm--Strange. Perhaps you had a bad batch or something...

Ive got a box of 25, 0.1uf 1000V K40Y-9 and the capacitance tolerance is supposed to be 10%. Ive checked them all and found to my surprise, they are all under 3% tolerance....

The 0.22uf 1000V 10% tolerance were a little wider at 7%, but still under the maker's claims.

The 0.47 630V 10% were a little better at about 6% tolerance...

The couple Ive checked for ESR were also low and of the same order for each same value one, gave up testing after 4 or 5......

Must have been rejects or a bad batch.

The ones I had were in a sealed manufacturers box of 25 pieces, kulled off the 'bay....
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Old 1st August 2011, 04:13 PM   #37
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The schematics is done!!!!!!!!!!!

So let's the fun begin!

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File Type: doc Mono Amp Tube.doc (62.0 KB, 137 views)
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Old 1st August 2011, 05:03 PM   #38
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From a first look, apart from parts of the power supply that are indecipherable, it seems to me that this guy knew what he was doing. wow.
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Old 2nd August 2011, 04:49 AM   #39
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I would need some help now to figure out what I need to update in my schematics. I was all excited to finally have the schematics and to be able to finally know what to do with the amp...

Last edited by murphythecat8; 2nd August 2011 at 04:55 AM.
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Old 2nd August 2011, 09:18 PM   #40
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Quote:
Originally Posted by DavesNotHere View Post
I'd put the Jensens back in, bypass them with a .1uf poly cap, if you have a cement resistor on your power output, change it with a non inductive resistor like is in speaker crossovers.

also, consider your input impedance. calculations worry about bias more than the input load. Start the grid to ground resistor at 1M and go down till the phasey sound is eliminated in the sound stage. you'll notice a gain increase as you reach the proper input impedance and as the total circuit becomes resonate, the white noise will go down.

I never liked any Russian caps as they are not consistent in quality ( esr fluctuates too much from cap to cap)
Can you elaborate here? It's really interesting, but I'm really not enough confident or knowledgeable...

What should be the bias results?
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