HI,
to everyone, I am new in this forum and I hope I can share with you my audio experinces. Well, I am not so good in DIY as you guys but I like to understand and doing things, that is why I joined this forum.
I was forgetting to say sorry for my really bad English grammar!
So my question is abut power supplies. I would like to build a power supply using the EZ81 tube rctifier, like the hybrid schematics a' la Counterpoint. I should have 25V ac as my output, I couldn't find any schematics on the web, do you you have some suggestion?
Thank you,
KEPha
to everyone, I am new in this forum and I hope I can share with you my audio experinces. Well, I am not so good in DIY as you guys but I like to understand and doing things, that is why I joined this forum.
I was forgetting to say sorry for my really bad English grammar!
So my question is abut power supplies. I would like to build a power supply using the EZ81 tube rctifier, like the hybrid schematics a' la Counterpoint. I should have 25V ac as my output, I couldn't find any schematics on the web, do you you have some suggestion?
Thank you,
KEPha
HI!
Thank you, anyway I am still curious how to that, I have a poweramp to which I have to tweak the supply, I would try with that, have you any reference,
bye
KEPha
Thank you, anyway I am still curious how to that, I have a poweramp to which I have to tweak the supply, I would try with that, have you any reference,
bye
KEPha
HI,
I will try to be clearer. I want to have a look to some schematics of power supplies which use the EZ81.
I have never seen one, but I heard that they are excellent in their job.
I heard about this tube because Counterpoint used to in its amp systems. I don't know more than this.
Thank you, have a nice day
I will try to be clearer. I want to have a look to some schematics of power supplies which use the EZ81.
I have never seen one, but I heard that they are excellent in their job.
I heard about this tube because Counterpoint used to in its amp systems. I don't know more than this.
Thank you, have a nice day
Its like any tubeamp power supply with a rectifier tube, centertapped transformer winding about 300v per side, 6.3v filament winding. Max capacitance you can have on the EZ81 cathode is about 50µF, if higher the tube breaks sooner. I had a amp with EZ81, it only had RC links in the power supply but if you have a choke you get cleaner B+ with less hum. The anodes goes to the transformer and the cathode is the DC output.
Hi KEPha,
The Counterpoint SA-100 uses a SS rect bridge for an HV output of approx +330 VDC. You can use an EZ-81 if you want. In any case, you will want to use a voltage regulator to isolate the voltage amp stage from variations in the DC level. Your amp will motorboat if you don't.
The SA-220 uses a tube rectifier and much higher DC voltages as they tried to filter these variations out. Not terribly successfully.
Counterpoint has many problems, so don't copy it or you will too!
-Chris
The Counterpoint SA-100 uses a SS rect bridge for an HV output of approx +330 VDC. You can use an EZ-81 if you want. In any case, you will want to use a voltage regulator to isolate the voltage amp stage from variations in the DC level. Your amp will motorboat if you don't.
The SA-220 uses a tube rectifier and much higher DC voltages as they tried to filter these variations out. Not terribly successfully.
Counterpoint has many problems, so don't copy it or you will too!
-Chris
EZ81's ain't so EZ. I find them frightfully scarce and would not design any circuit around them. They are used in my Heathkit EA-3's and I cannot find anything else that will sub without going to an octal socket change and using perhaps a 6X5.
My advice, go with a 5U4. heavy duty and you can find them all over the place. Needs 5V dedicated filament supply however. The B+ output will appear on this circuit.
My advice, go with a 5U4. heavy duty and you can find them all over the place. Needs 5V dedicated filament supply however. The B+ output will appear on this circuit.
EZ81/6CA4s aren't that scarce (I think Electro-Harmonix distribute new production 6CA4s...), but nowadays IN4007s and the like are so common 😉
Failing that, you could always use a pair of TV damper diodes, which will likely have a lower voltage drop, higher current capability and are most likely cheaper (plus, they look nicer).
Failing that, you could always use a pair of TV damper diodes, which will likely have a lower voltage drop, higher current capability and are most likely cheaper (plus, they look nicer).
audiousername said:
1N4007's are fine if you can put up with or deal with the switching noise and instant-on HV that will be higher than with the tube rectifier. Damper tube diodes are a great way to go but now you are talking two octal sockets and a hefty 6.3 volt reserve on the existing filament winding of the power transformer if retrofitting a not-so-EZ81 application.
The reason I say EZ81's are scarce is because I have thousands of tubes from a lifetime of collecting, and hundreds of power rectifier tubes including (from memory) 5U4, 5AS4, 5Y3, 5Y4, 5AR4, 5V4, 80, 6X4, 6X5, 6W4, 6AU4, 6AX4, 6DW4, 6BL4, 816, 866, 872B, 3B28 and the list goes on, but no bloody EZ81's. If they were indeed common, I'd have acquired at least some in my inventory.
I'd spec on of my own tubes from inventory any day in preference to buying any ElectroHarmonix tube. Vintage and NOS beat the current offerings hands down. I do hope the tube resurection grows large enough that some quality will begin to show up in valve production again. It seems like either the trade secrets were lost, or the desire to make quality was lost, or both.
Hi Rob,
The tubes I have from Electroharmonix have been fine. Have you tried any yet? I will say they are consistant. I've only had one noisy 12AX7 from them. Their 6L6EH survive in Fender Twins and Mesa Boogie Barons, more than I can say from almost any other brand I have tried.
In a perfect world, I'd be using an endless supply from RCA or similar. Electroharmonix are the best new production I've seen.
-Chris
The tubes I have from Electroharmonix have been fine. Have you tried any yet? I will say they are consistant. I've only had one noisy 12AX7 from them. Their 6L6EH survive in Fender Twins and Mesa Boogie Barons, more than I can say from almost any other brand I have tried.
In a perfect world, I'd be using an endless supply from RCA or similar. Electroharmonix are the best new production I've seen.
-Chris
Chris,
I bought some Fat Bottle 6CA7 EH and segments of the screen grid wires are incandescent! They are going back! The envelope and base looks identical to the Sovtek 6L6WXT which I have found is JUNK. I would guess theye are made in the same plant.
BTW, haven't forgotten about you, just been bizzy trying to get back to where I already was. No time for audio yet this year.
I bought some Fat Bottle 6CA7 EH and segments of the screen grid wires are incandescent! They are going back! The envelope and base looks identical to the Sovtek 6L6WXT which I have found is JUNK. I would guess theye are made in the same plant.
BTW, haven't forgotten about you, just been bizzy trying to get back to where I already was. No time for audio yet this year.
Hi Rob,
I'm busy too! 'sokay!
I use those exact tubes in my Eico HF-87a - no problems. And I stuck them in a Baron (against my better judgement, cust request), it hasn't come back yet. I did get some 6L6EH improperly labeled once. Sent them back before use. I wonder ..... I agree the 6L6WXT are sub standard. More like 6L6GA types.
Hope you are feeling well, soon all the evil white @%&$! will be gone. Maybe someone will show up for work!!
-Chris
I'm busy too! 'sokay!
I use those exact tubes in my Eico HF-87a - no problems. And I stuck them in a Baron (against my better judgement, cust request), it hasn't come back yet. I did get some 6L6EH improperly labeled once. Sent them back before use. I wonder ..... I agree the 6L6WXT are sub standard. More like 6L6GA types.
Hope you are feeling well, soon all the evil white @%&$! will be gone. Maybe someone will show up for work!!
-Chris
- Status
- Not open for further replies.