filament transformer vs plate transformer

contaxchen · 12th January 2005, 03:46 AM

Hi all,
Does anybody know the funadamental difference between filament and plate transformer? Does filament transformer got more regulation than plate transformer, given the same output voltage?
Any expert?

LungHui Chen

SY · 12th January 2005, 04:00 AM

A filament transformer will be wound to give a voltage appropriate for filaments (or heaters), most commonly 2.5, 6.3, or 12.6V. A plate transformer will generally be wound to give an appropriate voltage for tube plates, typically in the hundreds of volts.

contaxchen · 12th January 2005, 08:07 PM

Ok,
I have some filament transformers with 80v ac... That's quiet high, isn't it? After doubling the voltage, what's the difference between a regular plate transformer?
Lchhen

SY · 12th January 2005, 08:12 PM

At 80vac, they're unlikely to be filament transformers. But with a voltage doubler, there's no reason you couldn't use tham for plate supplies.

There have been tubes made with high-ish filament voltage requirements, but they're nearly all intended for transformerless use (once common in TVs and radios, but abandoned as FAR too dangerous).

ray_moth · 13th January 2005, 08:27 AM

SY already said it. The other important difference is that filament transformer secondary windings have thick wire to supply several amps, wheareas plate transformers are wound with quite thin wire because they need to supply only a fraction of an amp (typically 50 mA - 500 mA).

Shoog · 13th January 2005, 06:10 PM

Will the filament transformer have a poor frequency response.
I am using a filament transformer of 6.3V ac to drive some speaker line transformers in order to get 70V ac. Is the filament transformer likely to be constricting the frequency response of the line transformers ?

Shoog

contaxchen · 14th January 2005, 03:43 AM

Hi,
I know filament transformer got bigger wire and supplies a few amps...
Shoog's question is really meaningful.

Anybody else?

audiousername · 14th January 2005, 06:54 AM

Shoog, the transformer should not have an effect on the frequency response. It is there to provide a voltage. In any case, the transformer is effectively shorted out by the last cap in the power supply (for audio signals).

The drawback of connecting two transformers in series (i.e. stepping the voltage down, then up again) is increased losses - since you are using two transformers. As such it is possible (though not very likely) that the power supply will have such poor regulation that it will sag on demanding passages of music (especially containing bass), but this is the effect of reduced power, not compromised frequency response.

In any case, I don't quite get what you mean by 'constricting the frequency response of line transfomers' - they are being used as power transformers aren't they?

Jason

Shoog · 14th January 2005, 10:16 AM

What I mean by restricting the frequency response is -

Torodial power transformers have a different sound to EI's, so they are effecting the power delivery at certain frequencies. The same question is relivent to filament transformers is it not?

Shoog

audiousername · 14th January 2005, 10:22 AM

Shoog,

The EI type of transformer tends to have a narrower bandwidth than toroids, so more of the HF noise and other rubbish is attenuated. Is that what you mean?

Jason

12th January 2005, 03:46 AM	#1
contaxchen diyAudio Member Join Date: Aug 2003 Location: Indiana USA	filament transformer vs plate transformer Hi all, Does anybody know the funadamental difference between filament and plate transformer? Does filament transformer got more regulation than plate transformer, given the same output voltage? Any expert? LungHui Chen

12th January 2005, 04:00 AM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX	A filament transformer will be wound to give a voltage appropriate for filaments (or heaters), most commonly 2.5, 6.3, or 12.6V. A plate transformer will generally be wound to give an appropriate voltage for tube plates, typically in the hundreds of volts. __________________ "It is not seemly, after wiping your nose, to spread out your handkerchief and peer into it as if pearls and rubies might have fallen out of your head." - Erasmus

12th January 2005, 08:12 PM	#4
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX	At 80vac, they're unlikely to be filament transformers. But with a voltage doubler, there's no reason you couldn't use tham for plate supplies. There have been tubes made with high-ish filament voltage requirements, but they're nearly all intended for transformerless use (once common in TVs and radios, but abandoned as FAR too dangerous). __________________ "It is not seemly, after wiping your nose, to spread out your handkerchief and peer into it as if pearls and rubies might have fallen out of your head." - Erasmus

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12th January 2005, 08:07 PM	#3
contaxchen diyAudio Member Join Date: Aug 2003 Location: Indiana USA	Ok, I have some filament transformers with 80v ac... That's quiet high, isn't it? After doubling the voltage, what's the difference between a regular plate transformer? Lchhen

13th January 2005, 08:27 AM	#5
ray_moth diyAudio Moderator Emeritus Join Date: Jan 2004 Location: Jakarta	SY already said it. The other important difference is that filament transformer secondary windings have thick wire to supply several amps, wheareas plate transformers are wound with quite thin wire because they need to supply only a fraction of an amp (typically 50 mA - 500 mA).

13th January 2005, 06:10 PM	#6
Shoog diyAudio Member Join Date: Aug 2002 Location: Eire	Will the filament transformer have a poor frequency response. I am using a filament transformer of 6.3V ac to drive some speaker line transformers in order to get 70V ac. Is the filament transformer likely to be constricting the frequency response of the line transformers ? Shoog

14th January 2005, 03:43 AM	#7
contaxchen diyAudio Member Join Date: Aug 2003 Location: Indiana USA	Hi, I know filament transformer got bigger wire and supplies a few amps... Shoog's question is really meaningful. Anybody else?

14th January 2005, 06:54 AM	#8
audiousername diyAudio Member Join Date: Jul 2004 Location: Melbourne, Victoria	Shoog, the transformer should not have an effect on the frequency response. It is there to provide a voltage. In any case, the transformer is effectively shorted out by the last cap in the power supply (for audio signals). The drawback of connecting two transformers in series (i.e. stepping the voltage down, then up again) is increased losses - since you are using two transformers. As such it is possible (though not very likely) that the power supply will have such poor regulation that it will sag on demanding passages of music (especially containing bass), but this is the effect of reduced power, not compromised frequency response. In any case, I don't quite get what you mean by 'constricting the frequency response of line transfomers' - they are being used as power transformers aren't they? Jason

14th January 2005, 10:16 AM	#9
Shoog diyAudio Member Join Date: Aug 2002 Location: Eire	What I mean by restricting the frequency response is - Torodial power transformers have a different sound to EI's, so they are effecting the power delivery at certain frequencies. The same question is relivent to filament transformers is it not? Shoog

14th January 2005, 10:22 AM	#10
audiousername diyAudio Member Join Date: Jul 2004 Location: Melbourne, Victoria	Shoog, The EI type of transformer tends to have a narrower bandwidth than toroids, so more of the HF noise and other rubbish is attenuated. Is that what you mean? Jason

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