Yes, shortly i will. Just alot of other work
Is it possible to use this tubes together with another circuit? I have not seen any other circuit than a srpp with 6n3 (or more tubes) I will try one if you have one. If it's lower gain then ofcourse just better. I like it simple
I just have little or no experience in tubes/circuits as you can read.
BUT i can solder and and understand pins and so on so if i have a schematic written i can probably make it work. (so why did i buy this crap hehe
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That's seems to be the general consensus for users rolling in NOS Russian tubes.
jeff
Max,
You should not get hum (from the heater at least) in your circuit. Heaters have been operated with 6,3V a.c. before with inputs of 2 mV, but correct balancing/centre-tapping and routing of leads are necessary.
What Cjpkg was referring to above is the matter of heater-cathode voltage. If the heater supply is earthed, the top tube cathode sits at about +80 - +100V with regard to the heater. While this is in order spec-wise, it allows for the cathode to get leakage electrons from the heater (inside the cathode tube, operating like a diode). If the heater supply is ac, such leakage will definitely cause hum.
It is therefore better and also common practice to operate the heater at a d.c. voltage higher than that of any cathode, so as to cut-off any diode-operation. In your circuit that would mean at least some 120V positive, as the top cathode sits at some 100V above earth. This is dangerous as the maximum neg. heater-cathode rating (100V) is then exceeded in the bottom triode.
The best you can do is to try connecting the heater supply to a resistor tapping of about +80V above earth (bypassed to earth). This is especially necessary when operating heaters from 6V.a.c. as explained above. Occasionally one gets a particularly 'leaking' tube between heater and cathode, which must then be discarded or used elsewhere.
Hallo Johan, nice name. It's my real name too =)
Now i learned something. Very useful info for me. I was just thinking about the grounding cuz when i'm connecting "via the board" the heater automatic gets earthed together with the rest (caps and so on) but now with ac i don't have any ground at all. Just direct from transformer to heaters.
If i would like to bypass to earth, what would your suggesting be in terms of resistance? what is normal? 10ohm or 10K? I really don't know how to calculate that.
If i would like to have DC i clearly need to buy a new transformer that delivers maybe 8-9V so i can get proper regulation and voltage out from this L7806.
Here is little updated schematic how it looks today:
Attachments
Some datasheets recommend no more than 20k resistance between cathode and heater, with exceptions for cathode followers and LTPs.
Nothing inside a valve envelope should be left to 'float', as it could pick up stray electrons and go negative or emit electrons (thermally or via secondary emission) and go positive.
Nothing inside a valve envelope should be left to 'float', as it could pick up stray electrons and go negative or emit electrons (thermally or via secondary emission) and go positive.
just run 2 300 ohm resistors from your heater AC terminals at the transformer and then tie the centers either to ground or to a voltage divider from your B+ with something like a 300K on top and a 100K on the bottom to ground.
One thought. How about the heater wiring to the tube rectifier? What i can see it's not "grounded" either before intering 6u4.. Look at the pic. Maybe it's possible to do the same on that 6.3v from transformer? (transformer have two independant 6,3V)
Attachments
While i'm at it some more pics.
This is very DIY... Later on thinking putting transformer on top of chassie with a cover and drill holes for tubes so they are "outside" and hardwire everything and make it neat. That's of course if i'm happy with it in the end
This is very DIY...
Later on thinking putting transformer on top of chassie with a cover and drill holes for tubes so they are "outside" and hardwire everything and make it neat. That's of course if i'm happy with it in the end Attachments
I did that first one with 2x330 ohm and hum went down but still there mostly in midrange and the woofers. If i touch the woofers before this mod, it was an exercusion of maybe +/- 1mm and now maybe 0,1mm.
How much will the voltage divider do? Have an 330K and 100k here I see.
Something that is strange is the "sparkling water" sound in tweeter... same "problem" with chinese tubes. Ok only hear these while listening close up with my ears.
How much will the voltage divider do? Have an 330K and 100k here I see.
Something that is strange is the "sparkling water" sound in tweeter... same "problem" with chinese tubes. Ok only hear these while listening close up with my ears.
those voltage divider values are fine.
Are they the tubes that came with the amp or did you have them separately?
What mA are they actually running at, each section of each tube?
I have found that hisss or sparkling water sound when I tube roll some tubes through my aikido pre. 6cg7's are particularly finicky, no rhyme or reason some hiss, some dont. Doesnt matter if they are running hot or colder.
Are they the tubes that came with the amp or did you have them separately?
What mA are they actually running at, each section of each tube?
I have found that hisss or sparkling water sound when I tube roll some tubes through my aikido pre. 6cg7's are particularly finicky, no rhyme or reason some hiss, some dont. Doesnt matter if they are running hot or colder.
The russian i have now i bought separately. I will try the divider tomorrow probably.
Before i brake something i must ask, between what pins do i check mA on these? They don't get very hot... fingervarm max.
I wanted to that couple of days ago but thinking maybe i screw up I'm not so used to measure electricity. Have been mostly ohm/C/mH
http://frank.pocnet.net/sheets/113/6/6N3P.pdf
Before i brake something i must ask, between what pins do i check mA on these? They don't get very hot... fingervarm max.
I wanted to that couple of days ago but thinking maybe i screw up
I'm not so used to measure electricity. Have been mostly ohm/C/mHhttp://frank.pocnet.net/sheets/113/6/6N3P.pdf
Voltage divider did good. Now hum is down to ok levels. Thx.
Been trying to find an answer how to measure the mA correct. Either it's to technical explanation or something else. Why can't it be something like "put red probe here and black there and you find out what mA your tube running at"
I never seem to find the "easy" answers
Been trying to find an answer how to measure the mA correct. Either it's to technical explanation or something else. Why can't it be something like "put red probe here and black there and you find out what mA your tube running at"
I never seem to find the "easy" answers
Measured voltage again, now the two heaters are 6,19V each and B+ is down to 211V.
Credits to cjkpkg for helping me with this hum problem. And drew a nice schematic that made it super easy =)
Also got my Alps RK27 50K from Germany (so i think it's genuine) and sound became a bit dark (?) Replaced a chinese 20K. Now it's quiet when volume is turned all the way down but to honest, i don't like the sound as much now. A bit muffled/dark in the top.
Credits to cjkpkg for helping me with this hum problem. And drew a nice schematic that made it super easy =)
Also got my Alps RK27 50K from Germany (so i think it's genuine) and sound became a bit dark (?) Replaced a chinese 20K. Now it's quiet when volume is turned all the way down but to honest, i don't like the sound as much now. A bit muffled/dark in the top.
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