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Old 26th February 2010, 11:11 AM   #891
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Quote:
Originally Posted by gabanyayaya View Post
quanghao

Do you still have this I/V boards for the 6H6P ?
No! i have not This I/V, I say you can mod I/V use 5687 for use 6h6p.

If you like i can gift for you one PCB 5687, and you cand mod it! it is easy!
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Old 26th February 2010, 11:43 AM   #892
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at some point i am going to try this, or something very similar. A more modern twist on the iv stage.

Thats a very quick sketch up so probably many errors but the basic approach should be readable.

Click the image to open in full size.

the 6n6p has 800ma heater current so a similar load to the 5687 so the PS could remain as it is.

Rset should be for 30ma, as its a paralellel arrangement. I would try it with just one side of the triode first to be honest.

Last edited by adamus; 26th February 2010 at 11:45 AM.
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Old 26th February 2010, 11:51 AM   #893
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Nice! but the Cap out put you cann use bigger!
Dont like CCS in anod for Tube 6h6, and 6h30
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Last edited by quanghao; 26th February 2010 at 11:56 AM.
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Old 26th February 2010, 11:57 AM   #894
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yes, it meant to say 1uf, as i said, its sketchup so many mistakes, and rather vital resistor values missing. I'll do some work on it when i get chance and perfboard it.

I have found an improvement with CSS. You do loose some of that romantic 'tube sound' as distortion drops significntly.
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Old 26th February 2010, 02:09 PM   #895
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Quote:
Originally Posted by adamus View Post
yes, it meant to say 1uf, as i said, its sketchup so
I have found an improvement with CSS. You do loose some of that romantic 'tube sound' as distortion drops significntly.
Yes I know it, CCS is very good with some kind of tube, but I really do not like CCS for 6h6 and 6h30 at anod.
The sound of it is skewed, not natural.
I agree with you about using LED instead of the resistance
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Last edited by quanghao; 26th February 2010 at 02:13 PM.
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Old 26th February 2010, 02:12 PM   #896
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Salas.

I am testing the shut reg for the +5 dig that wont go above 5.16.

Leds are dropping 3.92v and the trimmer is dropping 0.75v at 161 ohms. combined vref of 4.67

I through trimmer = 0.75/161 = 4.6ama, which seems low for the jfet (originally matched at 7ma idss @10v.

Strnage thing is, the trimmer has more turns left, but it doesnt affect the voltage.

any thoughts from the wizards?

Last edited by adamus; 26th February 2010 at 02:16 PM.
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Old 26th February 2010, 02:18 PM   #897
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Quote:
Originally Posted by adamus View Post
Salas.

I am testing the shut reg for the +5 dig that wont go above 5.16.

Leds are dropping 3.92v and the trimmer is dropping 0.75v at 200 ohms. combined vref of 4.67

I through trimmer = 0.75/200 = 3.7ma, which seems very low for the jfet (originally matched at 7ma idss @10v.

Does this point to my problem?
Do you seen my post 885????

You can to not connect to board DAC. what is the happen??
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Old 26th February 2010, 02:21 PM   #898
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board not connect i can set the voltage to 5.5 volts without problem.

Connect the board and the voltage drops to 5.16 max. its plays mucis very well, but something must be slightly wrong
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Old 26th February 2010, 02:27 PM   #899
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Quote:
Originally Posted by adamus View Post
board not connect i can set the voltage to 5.5 volts without problem.

Connect the board and the voltage drops to 5.16 max. its plays mucis very well, but something must be slightly wrong
Salas works well, not in it,
probably Board DAC have something wrong place, you can check please!

if you are in doubt about this?
so the voltage you measured at the foot of Cs8414 and 74hc04 is like?
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Old 26th February 2010, 02:35 PM   #900
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the 5v dig line is 5.16

I have taken the chips out to rule them out, and the voltage is still 5.16, so it must be one fo the tl431's or a short somewhere.
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