Pi wound output transformers

Tyimo · 18th February 2011, 06:41 PM

Hi!
I read many nice thing about Pi wound output transformers.
I know that Pi wound transformers are 100% symmetrically balanced and have 2X greater high frequency response than a conventional layer wound output transformers.
Pi-winding helps to breakup series resonance at high frequencies. etc.
Does anybody have experience with this technique?
Is it realy works?

greets:
Tyimo

pieter t · 18th February 2011, 06:53 PM

Quote:

Originally Posted by Tyimo

Hi!
I read many nice thing about Pi wound output transformers.
I know that Pi wound transformers are 100% symmetrically balanced and have 2X greater high frequency response than a conventional layer wound output transformers.
Pi-winding helps to breakup series resonance at high frequencies. etc.
Does anybody have experience with this technique?
Is it realy works?

greets:
Tyimo

When you know why do you ask if it works?

Knarf · 18th February 2011, 07:04 PM

It certainly works for tuning coils used at lower radio frequencies, like 100KHz-1MHz. By using a pie wound (not 'pi') coil, you reduce the parasitic capacitance across the coil for a given physical size, thus increasing its quality factor, Q. This is very important in many radio application, like when trying to make sharp bandpass filters.

Whether this makes any difference in audio transformers I cannot say...

pieter t · 18th February 2011, 07:07 PM

I know where the "information" comes from.
As long as the claim is not backed up by reliable measurment with an audio transformer, it does not make sense.
The site has useful info and a bit of nonsense anyway.

Tyimo · 18th February 2011, 07:08 PM

Quote:

When you know why do you ask if it works?

I know it unfortunately only theoretically...
And please, just smile!

Tyimo · 18th February 2011, 07:11 PM

Quote:

I know where the "information" comes from.

For example from here:
Lenard Audio - Education - Valve Amps

pieter t · 18th February 2011, 07:14 PM

Yeah Tyimo I know.
What I said, some useful information but also some nonsense (the cathode bias classA for instance).

LinuksGuru · 18th February 2011, 08:03 PM

Personally I prefer toroids. Unlike many contrary beliefs, it is not a problem to design and build audio output toroids which don't suffer from core saturation caused by DC imbalance of output stage idle current.

I have a pair of 60W 5K PP toroids which can sustain 15 mA imbalance at 36W/20 Hz (lover frequency = higher flux density). I didn't tested them yet at full load, need to build power resistor network first.

Many people are obsessed with exotic techniques, but simply put, this is not necessary. Its possible to build excellent transformer with either EI, Double C, or toroid. The rest is up to availability of material and price.

18th February 2011, 06:41 PM	#1
Tyimo diyAudio Member Join Date: Nov 2002 Location: Hungary	Pi wound output transformers Hi! I read many nice thing about Pi wound output transformers. I know that Pi wound transformers are 100% symmetrically balanced and have 2X greater high frequency response than a conventional layer wound output transformers. Pi-winding helps to breakup series resonance at high frequencies. etc. Does anybody have experience with this technique? Is it realy works? greets: Tyimo

18th February 2011, 07:04 PM	#3
Knarf diyAudio Member Join Date: Aug 2004 Location: Denmark	It certainly works for tuning coils used at lower radio frequencies, like 100KHz-1MHz. By using a pie wound (not 'pi') coil, you reduce the parasitic capacitance across the coil for a given physical size, thus increasing its quality factor, Q. This is very important in many radio application, like when trying to make sharp bandpass filters. Whether this makes any difference in audio transformers I cannot say... __________________ Team Thermionic

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18th February 2011, 07:07 PM	#4
pieter t diyAudio Member Join Date: Apr 2009	I know where the "information" comes from. As long as the claim is not backed up by reliable measurment with an audio transformer, it does not make sense. The site has useful info and a bit of nonsense anyway.

18th February 2011, 07:14 PM	#7
pieter t diyAudio Member Join Date: Apr 2009	Yeah Tyimo I know. What I said, some useful information but also some nonsense (the cathode bias classA for instance).

18th February 2011, 08:03 PM	#8
LinuksGuru diyAudio Member Join Date: Aug 2008	Personally I prefer toroids. Unlike many contrary beliefs, it is not a problem to design and build audio output toroids which don't suffer from core saturation caused by DC imbalance of output stage idle current. I have a pair of 60W 5K PP toroids which can sustain 15 mA imbalance at 36W/20 Hz (lover frequency = higher flux density). I didn't tested them yet at full load, need to build power resistor network first. Many people are obsessed with exotic techniques, but simply put, this is not necessary. Its possible to build excellent transformer with either EI, Double C, or toroid. The rest is up to availability of material and price.

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