too much gain

[20to20]

i tried with one set but the voltage was still well above 6.2 and the second set brought it to just above 6 volts. i read somewhere that this will extend the life span of the tubes.

Diodes can have a range of voltage drop. If you look into 50v. schottkys they may have only .35v drop. Some diodes have over 1.5v drop. Also, the drop is usually rated as max drop at max current. If the diode is underloaded it might only drop 1/2 - 3/4 of the rated drop. I was running at 7.1v heater and now I'm at 6.15v. Cool and sweet.

FYI, this heater overvoltage runs tube testers hot, too. The tube is driven high and makes it score higher than it would or also when the life test is run at the next lower filament setting it may be seeing its normal design voltage, giving a false quality reading. I've adjusted my tube tester voltages to get them back to normal so I don't have to plug it into a variac to use it. So beware buying tubes, if you don't have a tester yourself, you may buy tubes from someone who thinks they're selling a good tube but is actually weak. If you adjust your filament voltage down, a weak tube will show right away. The tube sellers get away with this because most folks filaments voltages are too hot, too.

 

[chopchip]

I don't think any of this is necessary since IIRC you're using line level signal source but you wanted a preamplifier with cathode follower output utilizing 6N1P tubes and that's what I gave you schematic for.

People do many things that aren't necessary, I guess this is just one of those things If it was me I'd simply install the attenuator into the amplifier if it was missing it.

you are right lol. that is what im doing now.

i was led to believe that i needed a preamp somehow and i was sent on this odysey

is there any way i could use this for a phono preamp? do you have a schematic for that too? maybe? if you dont mind me asking.

what is IIRC?

thanks

 

[chopchip]

Diodes can have a range of voltage drop. If you look into 50v. schottkys they may have only .35v drop. Some diodes have over 1.5v drop. Also, the drop is usually rated as max drop at max current. If the diode is underloaded it might only drop 1/2 - 3/4 of the rated drop. I was running at 7.1v heater and now I'm at 6.15v. Cool and sweet.

FYI, this heater overvoltage runs tube testers hot, too. The tube is driven high and makes it score higher than it would or also when the life test is run at the next lower filament setting it may be seeing its normal design voltage, giving a false quality reading. I've adjusted my tube tester voltages to get them back to normal so I don't have to plug it into a variac to use it. So beware buying tubes, if you don't have a tester yourself, you may buy tubes from someone who thinks they're selling a good tube but is actually weak. If you adjust your filament voltage down, a weak tube will show right away. The tube sellers get away with this because most folks filaments voltages are too hot, too.

interesting!

 

[Soonerorlater]

what is IIRC?

Always wanted to know myself what that meant but was too afraid to ask

 

[TheGimp]

If I Recall Correctly.

If I Remember Correctly.

 

[Soonerorlater]

Thanx, TheGimp, I need to ask myself that more and more these days

 

[Arnulf]

is there any way i could use this for a phono preamp? do you have a schematic for that too? maybe? if you dont mind me asking.

I'm sorry, I don't have enough experience with phono stages to be of much help. Other do, I'm sure they'll chime in. The chassis you've got (with 4 noval sockets) could definitely be reused in such a role.

There are numerous schematics floating around, Google is your friend.

 

[Wavebourn]

The amplitude of the "spike" is so small it's hardly a spike, and the frequency is so high it's also ultrasonic. Even though it happens on each phase reversal, the duration is so short it's frequency is ultrasonic.

The worst thing is not a spike. It is variability of a voltage in power outlets. If to subtract from filament voltage some constant it's variation will be higher with variations of a primary voltage. Resistor is way much better.