High voltage regulator

[fdegrove]

Hi,

SY's right, class doesn't really apply here anyway.

And, as I think I've explained already : the whole discussion is moot as it's NOT the class of operation of the regulator_or any subpart of it for that matter_ that was refered to in the first place.

As for a regulator being necessary for a Class A device such as a preamp: no, they're not necessary at all.

However, if you look at the forest iso the trees you may realize it's not a bad idea to have a virtual battery as a PS for a preamp instead of relying on the quality of the mains supply.
Having a steady voltage for a B+ is a nice side effect....ergo.

Cheers,😉

 

[Sch3mat1c]

So tell me what these slow variations (no noise - that's damped by the filter, unless you haev a *really* bad setup) on the order of 2% do to an amplifier that is inherently unstable in the 5% range?

😀 😀 😀

Tim

 

[fdegrove]

Hi,

So tell me what these slow variations (no noise - that's damped by the filter, unless you haev a *really* bad setup) on the order of 2% do to an amplifier that is inherently unstable in the 5% range?

To someone actually not caring about audio it sure won't matter one way or the other.

Cheers,😉

 

[fdegrove]

Hi,

Current per ch is 14mA and plate voltage of the tube is 105Vdc. Thanks for Your replies- maybe this will help somebody (fdegrove ).

Daniel,

First of all, I'm not convinced by the circuit using the two triodes of the 5687 in //.
If you can avoid this_you sure can here_ then please do.
You probably don't need this amount of gain from a linestage if your primary source is CD.
In fact most people using preamps burn off most of the gain anyway.

If you're look to reduce the output impedance by putting the triodes in //, you can achieve much better results by opting for a SRPP stage or a derivative thereoff.
PSRR isn't an issue as you'll be building a very good PS anyway.

If you like you can of course use the 250VDC regulator I posted elsewhere and if it were me building the preamp I'd use an additional shunt regulator using a stack of OB2s preceded by a resistor to set the ignition voltage.
You'll probably end up a little short of 220Vs but that's no big deal.

By doing so I'm sure you'd get very good results and the final sonic quality of the preamp will then only depend on the quality of the remainder of the components.

Cheers,😉

 

[Sch3mat1c]

To someone actually not caring about audio it sure won't matter one way or the other.

Hahahah, hm well I guess Frank ran out of his explanation bag. Ah well.

Tim (listens to music)

 

[sparkle]

Hi,



Daniel,

First of all, I'm not convinced by the circuit using the two triodes of the 5687 in //.
If you can avoid this_you sure can here_ then please do.
You probably don't need this amount of gain from a linestage if your primary source is CD.
In fact most people using preamps burn off most of the gain anyway.

If you're look to reduce the output impedance by putting the triodes in //, you can achieve much better results by opting for a SRPP stage or a derivative thereoff.
PSRR isn't an issue as you'll be building a very good PS anyway.

If you like you can of course use the 250VDC regulator I posted elsewhere and if it were me building the preamp I'd use an additional shunt regulator using a stack of OB2s preceded by a resistor to set the ignition voltage.
You'll probably end up a little short of 220Vs but that's no big deal.

By doing so I'm sure you'd get very good results and the final sonic quality of the preamp will then only depend on the quality of the remainder of the components.

Cheers,😉

Thanks for that reply- will think of that- might do just that......
🙂
best regards
daniel