Tube rectifier input capacitance

regal · 1st February 2010, 02:12 PM

I made a mistake and ran a tube rectifier with a max 60uF spec into a PS with a 150uF input cap. Ran for about 8 hrs before I thought of it, the sound was a little harsh on the bass. Should this be cured by lowerering the cap? Could I have damaged the rectifier tube?

radiostar · 1st February 2010, 02:19 PM

Which rectifier tube do you have?

Sheldon · 1st February 2010, 02:25 PM

The input cap specification assumes a particular value for the resistance of the transformer and any added series resistance. So, without values, it's not possible to know if you've exceeded the rating. But if it's still working, you probably haven't done much damage - yet.

Sheldon

analog_sa · 1st February 2010, 02:28 PM

Quote:

Originally Posted by regal

Could I have damaged the rectifier tube?

Not very likely. QuickSilver were running parallel GZ34 into 330uF for the lifetime of their amps, so 8hrs seems quite safe. Not something i would recommend though.

bigwill · 1st February 2010, 06:27 PM

Don't sweat it, valves aren't wimps

tomchr · 1st February 2010, 11:51 PM

Too high cap usually results in arcing at turn-on due to the inrush current needed to fill the cap. If you didn't have any fireworks in the rectifier, I'd say it's probably fine.

~Tom

regal · 2nd February 2010, 06:01 AM

Quote:

Originally Posted by analog_sa

Not very likely. QuickSilver were running parallel GZ34 into 330uF for the lifetime of their amps, so 8hrs seems quite safe. Not something i would recommend though.

This was actually a GZ34 as well, I ordered a 60 uf Can to replace the 150uF electrolytic to be on th safe side.

Arnulf · 2nd February 2010, 09:05 AM

You could also add a choke, NTC or fixed resistor ahead of existing capacitor ...

barretter · 2nd February 2010, 10:15 AM

Thermistor OK, resistor OK, but if you make it a choke input supply, the output voltage will drop dramatically.

regal · 2nd February 2010, 12:54 PM

I think I'm going to add a 60uF cap + 100 ohm resistor then attach to the 150uf PS. PSUD shows this will reduce the ripple 75% and I only lose a few volts.

1st February 2010, 02:12 PM	#1
regal diyAudio Member Join Date: Jan 2004 Location: MD	Tube rectifier input capacitance I made a mistake and ran a tube rectifier with a max 60uF spec into a PS with a 150uF input cap. Ran for about 8 hrs before I thought of it, the sound was a little harsh on the bass. Should this be cured by lowerering the cap? Could I have damaged the rectifier tube?

1st February 2010, 02:19 PM	#2
radiostar diyAudio Member Join Date: Apr 2009	Which rectifier tube do you have? __________________ tubes.rs facebook.com/tubes.rs

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1st February 2010, 02:25 PM	#3
Sheldon diyAudio Member Join Date: Dec 2003 Location: San Diego	The input cap specification assumes a particular value for the resistance of the transformer and any added series resistance. So, without values, it's not possible to know if you've exceeded the rating. But if it's still working, you probably haven't done much damage - yet. Sheldon

1st February 2010, 06:27 PM	#5
bigwill diyAudio Member Join Date: Dec 2004 Location: UK	Don't sweat it, valves aren't wimps

1st February 2010, 11:51 PM	#6
tomchr diyAudio Member Join Date: Feb 2009 Location: Greater Seattle Area	Too high cap usually results in arcing at turn-on due to the inrush current needed to fill the cap. If you didn't have any fireworks in the rectifier, I'd say it's probably fine. ~Tom

2nd February 2010, 09:05 AM	#8
Arnulf diyAudio Member Join Date: Feb 2009	You could also add a choke, NTC or fixed resistor ahead of existing capacitor ...

2nd February 2010, 10:15 AM	#9
barretter diyAudio Member Join Date: Apr 2003 Location: West Yorkshire, UK.	Thermistor OK, resistor OK, but if you make it a choke input supply, the output voltage will drop dramatically.

2nd February 2010, 12:54 PM	#10
regal diyAudio Member Join Date: Jan 2004 Location: MD	I think I'm going to add a 60uF cap + 100 ohm resistor then attach to the 150uf PS. PSUD shows this will reduce the ripple 75% and I only lose a few volts.

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