tantalum cap

Nikon1975 · 22nd January 2010, 09:19 PM

What's the advantage to use tantalum caps instead of electrolitic for cathode resistor bypass ?

Best Regards,

Davide

woody · 22nd January 2010, 10:17 PM

I have heard tantalums sound bad. I bet you would be happier with a good
electrolitic.

Poindexter · 22nd January 2010, 10:33 PM

Some tantalums sound bad, some don't, but they are all rather unreliable and should not be used in critical circuit positions. All I have seen are low voltage - they were used as cathode resistor bypass caps in the olde dayes because of very compact size.

Nowadays, there are outstanding small electrolytic capacitors that are better, better sounding, more reliable, cheaper, and more available in more flavors than tantalum types. Where you see them is in old schematics.

Aloha,

Poinz
AudioTropic

Sch3mat1c · 23rd January 2010, 05:46 AM

Tantalums are exquisite capacitors, as long as you aren't pulling peak currents, which you certainly aren't in anything tube (peaks of 500mA even for a big stinking amp? ha), as long as you avoid reverse bias (duh, a tube is also a diode, and it's supplied with DC anyway), and as long as you avoid excess voltage (maybe not as easy with >>200V in reserve, but a cathode in proper running order won't change very much unless the tube itself goes Chernobyl, in which case the popped tantalum is the least of your worries).

Sound? It won't sound any different from anything else. Even the highest transconductance tube will have a cathode impedance way greater than even the crummiest aluminum electrolytic on the market. It's a silly proposition.

The better question is why you would bother spending money on tantalums when electrolytics are more than suitable.

Tim

Nikon1975 · 23rd January 2010, 08:13 AM

I was looking at this schematic Jean Hiraga 12AX7 Single Ended KT88 Tube Amplifier Schematic

I found interesting the level of details in the choice of components. Then I started to found explanation mainly for the use of mica and tantalum capacitor.

I was also surprise that I could not found anyone who actually assembled this amp.

Best Regards,

Davide

22nd January 2010, 09:19 PM	#1
Nikon1975 diyAudio Member Join Date: Nov 2009 Location: Tokyo	tantalum cap What's the advantage to use tantalum caps instead of electrolitic for cathode resistor bypass ? Best Regards, Davide

23rd January 2010, 05:46 AM	#4
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	Tantalums are exquisite capacitors, as long as you aren't pulling peak currents, which you certainly aren't in anything tube (peaks of 500mA even for a big stinking amp? ha), as long as you avoid reverse bias (duh, a tube is also a diode, and it's supplied with DC anyway), and as long as you avoid excess voltage (maybe not as easy with >>200V in reserve, but a cathode in proper running order won't change very much unless the tube itself goes Chernobyl, in which case the popped tantalum is the least of your worries). Sound? It won't sound any different from anything else. Even the highest transconductance tube will have a cathode impedance way greater than even the crummiest aluminum electrolytic on the market. It's a silly proposition. The better question is why you would bother spending money on tantalums when electrolytics are more than suitable. Tim __________________ See my Electronics webpage -- the home of Vacuum Tube Drag Racing. The key to being a successful Audiophile: "I reject your reality and substitute my own!"

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22nd January 2010, 10:17 PM	#2
woody diyAudio Member Join Date: Jan 2002 Location: Tyrone Ga. U.S.A.	I have heard tantalums sound bad. I bet you would be happier with a good electrolitic.

22nd January 2010, 10:33 PM	#3
Poindexter diyAudio Member Join Date: Oct 2004 Location: Maui, Hawai'i, USA	Some tantalums sound bad, some don't, but they are all rather unreliable and should not be used in critical circuit positions. All I have seen are low voltage - they were used as cathode resistor bypass caps in the olde dayes because of very compact size. Nowadays, there are outstanding small electrolytic capacitors that are better, better sounding, more reliable, cheaper, and more available in more flavors than tantalum types. Where you see them is in old schematics. Aloha, Poinz AudioTropic

23rd January 2010, 08:13 AM	#5
Nikon1975 diyAudio Member Join Date: Nov 2009 Location: Tokyo	I was looking at this schematic Jean Hiraga 12AX7 Single Ended KT88 Tube Amplifier Schematic I found interesting the level of details in the choice of components. Then I started to found explanation mainly for the use of mica and tantalum capacitor. I was also surprise that I could not found anyone who actually assembled this amp. Best Regards, Davide

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