I am going to build the phono stage with 6SL7/12SL7's. Can I keep the values from the schematic?
hello again :d
lately i am working on the case for my power supply 🙂
for the high tension i am using 5y3c rectifier tube , two stage lc filter(20h-100uf-10h-100uf) followed by 2 x OA2 and few resistors so i could drop voltage down to 250 volts
for filament i use 2 x 6.3v 2.5a windings one for the gain stage and one for the buffer stage(gain stage is done with 6h9c and buffer stage with 6h8c).each tube is cc powered(4x 10000 uf and 7806 regulator)
the ps of the gain stage has the ground connected to the ground of the high tension ps.for the buffer stage i tied in series 4 x 47k resistors connected on the + and ground of the high tension ps and tied the + from the filament of the buffer stage after the first resistor from ground to + so i could raise the filment voltage to protect tube`s life.
when i connect the + of the buffer`s stage at the voltage divider it aprears a little hum 🙁 it`s not very low frequency.i could hear it better on the tweeter , on the woofer is very low.
what should i try to do?
i want to replace the oa2 tubes with this 6GV8 / ECL85 based 250 volt tube regulator PCB voltage regulator but i don`t have another 6.3 volt and 0.9a winding.could i tie 6gv8 filament directly on one of the ac windings i already have? on which one?
thank you...hope to finish this soon
lately i am working on the case for my power supply 🙂
for the high tension i am using 5y3c rectifier tube , two stage lc filter(20h-100uf-10h-100uf) followed by 2 x OA2 and few resistors so i could drop voltage down to 250 volts
for filament i use 2 x 6.3v 2.5a windings one for the gain stage and one for the buffer stage(gain stage is done with 6h9c and buffer stage with 6h8c).each tube is cc powered(4x 10000 uf and 7806 regulator)
the ps of the gain stage has the ground connected to the ground of the high tension ps.for the buffer stage i tied in series 4 x 47k resistors connected on the + and ground of the high tension ps and tied the + from the filament of the buffer stage after the first resistor from ground to + so i could raise the filment voltage to protect tube`s life.
when i connect the + of the buffer`s stage at the voltage divider it aprears a little hum 🙁 it`s not very low frequency.i could hear it better on the tweeter , on the woofer is very low.
what should i try to do?
i want to replace the oa2 tubes with this 6GV8 / ECL85 based 250 volt tube regulator PCB voltage regulator but i don`t have another 6.3 volt and 0.9a winding.could i tie 6gv8 filament directly on one of the ac windings i already have? on which one?
thank you...hope to finish this soon
Hey All,
JJ lists the 12AX7 and the 7025 as the same tube. Is that correct? If not are there any recomendations on a brand for this tube? And if there are differences what are they?
Kevin
JJ lists the 12AX7 and the 7025 as the same tube. Is that correct? If not are there any recomendations on a brand for this tube? And if there are differences what are they?
Kevin
Last edited:
Any European ECC83 should have the twisted heater, but don't count on it for lesser brands. The history, as I understand it, is that we copied the US 12AX7 but added a low hum heater. The US then added a low hum heater too and called it the 7025. Before long all 12AX7 also had the low hum heater??
Is the power supply schematic correct? Where does the ECC83 pin 1 plate current go?
Thanks,
Chris
Thanks,
Chris
The one meg resistor. Yes, rather starved, which is often an interesting technique. The other tube has its own plate load as well as the stacked cathode load.
EL86/6CW5 is just an audio output pentode, like EL84/6BQ5 but lower impedance. I doubt if it is that critical. Line output valves (sweep tubes) are often used in PSUs.
Hi,
You'd end up with a totally different regulator alltogether.
The EL86 plays a major part due to it's high perveance, the voltage reference tubes should not be changed either even though some type may strike up.
That diagram belongs to a different preamp, I think.
The phono preamp uses a Brimar ECC807 as a diff amp.
As for the 1M resistor, it's there for a reason. It makes the error amp last like for ever and still do its job....
Cheers, 😉
You'd end up with a totally different regulator alltogether.
The EL86 plays a major part due to it's high perveance, the voltage reference tubes should not be changed either even though some type may strike up.
That diagram belongs to a different preamp, I think.
The phono preamp uses a Brimar ECC807 as a diff amp.
As for the 1M resistor, it's there for a reason. It makes the error amp last like for ever and still do its job....
Cheers, 😉
Last edited:
Hi,
No, it is not. That is for a line preamp feeding a ECC99. (Variation a theme preamp for CD/Line use I think)
Cheers, 😉
No, it is not. That is for a line preamp feeding a ECC99. (Variation a theme preamp for CD/Line use I think)
Cheers, 😉
We still don't know if the 2x ECC83 design I linked earlier is the one he's currently talking about either. I gave up on that as well.