Hello on all tube experts.Just finished tube preamp with E80CC tube ,but now I have the problem,that the output signal is verry,verry low and when I turn the 100Kohm stepped shunt attenuator till the end the signal is totaly distorted and only about 0.5Vrms.I have checked all the voltages and is all OK,i have put some other e80cc tube in and the same problem,I have put the ecc82 tube in and the same problem,I have disconect the attenuator and put the signal direct from my CD player on tube and the same problem,so now I have no more idea what there could be wrong.This is the shematic,the psu is CLCRC and the tube rectifier is 5852 tube,the anode supply is 250V dc,and the heater is DC 12,6V.
Plese if someone have some idea what could be wrong???😕
In the shematic is 12ay7 tube,I use one piece e80cc per chanel!!
Plese if someone have some idea what could be wrong???😕
In the shematic is 12ay7 tube,I use one piece e80cc per chanel!!
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...hi,the preamp is conected to power amp with 50Kohm input(load),The anode supply and the heater supply for E80CC are powered up in the same time.
I have disconect now the rectifer tube and made the anode supply with diodes full wave bridge and the problem is the same!
hope this helps.......
I have disconect now the rectifer tube and made the anode supply with diodes full wave bridge and the problem is the same!
hope this helps.......
You are saying that BOTH of the two separate stereo channels have the same problem?
Then it could be a wiring mistake done the same way in both channels. The power supply
isn't likely to cause a problem like this. Maybe a resistor value is very different from what
you think. Have you measured all of them? Maybe the input 1M is really 10R, etc.
....hi,yes the same problem in bouth chanel,I have cheked all the resistor value,and all are OK,I have cheked the wiring and all look OK,I cheked all voltages on the bouth anodes and cathodes and are OK,like in the schematic!
And the funny site of this is,that I have build some year ago the same preamp on the same schematic and it worked Ok.I realy must do something wrong,but after 3 days of working on the problem,I havent find what is the problem.
And the funny site of this is,that I have build some year ago the same preamp on the same schematic and it worked Ok.I realy must do something wrong,but after 3 days of working on the problem,I havent find what is the problem.
But the schematic you posted is for a 12ay7 not e80cc.Success is assured if you build it as drawn.Do you not have the 12ay7?
Happy building!
Happy building!
.....yes I know,but I was impresed for this peamp on this web page :Audio Note Kondo M77 Tube Pre-amplifier Clone DIY | Sound Kontrol
.....and the preamp truly sound verry good,with some good parts is verry good preamp.
.....and the preamp truly sound verry good,with some good parts is verry good preamp.
You put tubes in very nonlinear regime (only 1ma).
Change on first triode: Ra to 22K, Rk to around to 390 Ohm, and Rk on second triode to 18K-22K. And increise output capacitor to at least 2.2uF or 3.3uF.
Change on first triode: Ra to 22K, Rk to around to 390 Ohm, and Rk on second triode to 18K-22K. And increise output capacitor to at least 2.2uF or 3.3uF.
Have you tried adding a capacitor between the stages, you will also need a resistor to ground after the cap.
As matejsirk wrote, the anode current is very low. E80CC could be operated at 10 mA, you need to reduce all resistors accordingly. Or you can try an ECC83 without any component change (note: different pinout and heater).
ECC83 is not good choice for line preamp - to high gain. There is lot of suitable tubes for line preamp: ECC82, 6N1P, 6N6P, 6CG7,....
I suspect everything is wrong 🙁
Looking at the tube data i get totally different (not very nice) voltages.
Mona
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......Hi Guys,thanks a lot for your all help.So I have today made some pictures from the pin to pin wiring.I just mesured again all the voltages and it look like this:
on first anode(pin1) on socket =110,8Volts
on the first cathode(pin3)on the socket=2,89volts
on the second anode(pin6) on the socket=255,2volts
on the second cathode(pin8)on the socket=115,5volts.
The HT+ is 255,2 volts!I use like I say before all the same resistsors only the one cathode resistor on input stage is 2,2Kohm becouse i have not become the 2Kohm like in the scematic!!The signal come in thru 0,1uF mkp capacitor and goes to pin 2!!The heater are on the pin4&5 and is DC regulated with 12,6 volts.
So guys what will be than your choice of the operating points for the e80cc tube??What for the resistors must I use???
on first anode(pin1) on socket =110,8Volts
on the first cathode(pin3)on the socket=2,89volts
on the second anode(pin6) on the socket=255,2volts
on the second cathode(pin8)on the socket=115,5volts.
The HT+ is 255,2 volts!I use like I say before all the same resistsors only the one cathode resistor on input stage is 2,2Kohm becouse i have not become the 2Kohm like in the scematic!!The signal come in thru 0,1uF mkp capacitor and goes to pin 2!!The heater are on the pin4&5 and is DC regulated with 12,6 volts.
So guys what will be than your choice of the operating points for the e80cc tube??What for the resistors must I use???
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There is something curious going on. The voltages don't correspond to a E80CC.
A tube that can give these values is the 6N3P but has a different pinout ??
Mona
A tube that can give these values is the 6N3P but has a different pinout ??
Mona
...hi Mona,I dont know if there are going something totaly wrong,but I have mesured the voltages for several times now and values that I wrote are corect.
In the photo I can see what looks like coax feeding the first grid. What I can't see is where the coax shield is grounded.
When strange things happen in circuits, including apparently vaguely sensible DC values but no signal amplification or distortion/hum, I always suspect parasitic oscillation. The absence of grid stoppers and the slightly haphazard layout could aid this - and the input coax with no shield?
When strange things happen in circuits, including apparently vaguely sensible DC values but no signal amplification or distortion/hum, I always suspect parasitic oscillation. The absence of grid stoppers and the slightly haphazard layout could aid this - and the input coax with no shield?