Single-ended-series amp with a "1 winding" transformer - Page 3

woody · 15th September 2007, 08:13 AM

I don't think this is single ended.

tubee · 15th September 2007, 09:35 AM

Is it single ended or pp? Here is a comment on this (solid state example though)

http://www.tcaas.btinternet.co.uk/jlhoutput.pdf

The rail voltage is single for sure

smoking-amp · 15th September 2007, 04:56 PM

"Is it single ended or pp?"

With matched current drives, as in the JLH output, or with matched voltage drives, as in the bootstrapped drive (Yvesm schematic), the even harmonic distortion products will cancel (for matched output devices), so they are obviously P-P.

Don

tubee · 15th September 2007, 05:11 PM

It is a pseudo push-pull design. At around 1969 it was difficult to make complementary transistors, so they designed (iron or no-iron) pseudo-pp amps, no need for expensive transistor-couples (and matching) Philips and others came with some of those designs.

PP indeed eleminates 2nd order harmonics. The use of a triode in the first stage creates some even harmonics, all together the amp could sound very neutral due to the combination of "even" & "odd" stages. But i am unaware what the bootstrap will do to the harmonic distorsion., (bootstrap = positive feedback)

smoking-amp · 15th September 2007, 05:34 PM

The splitter bootstrap guarantees equal grid to cathode drive voltage on the top output tube. Since it references the equal voltage drop on the top 82K (versus the bottom 82K) splitter resistor to the top tube's cathode (which the bottom drive already does too).

Since the splitter bootstrap is not increasing the top grid drive versus the bottom grid drive, it should not be creating any additional distortion here. Really just has the same effect as one would get using an interstage transformer with two floating secondaries. (Remind me not to buy any interstage transformers, how stupid!)

Don

tubee · 17th September 2007, 05:32 PM

Talking about interstage transformeres: had 2 identical ones with special mu core, one i demolisched as study-object, i am now sorry i did.

Did some thinking to add a cap and a autotransformer, not easy with the bootstrap.

tubee · 17th September 2007, 07:04 PM

Is this gonna work?

tubee · 17th September 2007, 07:15 PM

Little improvement, speaker on one side grounded

15th September 2007, 09:35 AM	#22
tubee diyAudio Member Join Date: Jul 2004 Location: Netherlands	Is it single ended or pp? Here is a comment on this (solid state example though) http://www.tcaas.btinternet.co.uk/jlhoutput.pdf The rail voltage is single for sure __________________ Daisy Bell

15th September 2007, 04:56 PM	#23
smoking-amp diyAudio Member Join Date: Dec 2001 Location: Hickory, NC	"Is it single ended or pp?" With matched current drives, as in the JLH output, or with matched voltage drives, as in the bootstrapped drive (Yvesm schematic), the even harmonic distortion products will cancel (for matched output devices), so they are obviously P-P. Don __________________ Ohms Law V = I R

15th September 2007, 05:11 PM	#24
tubee diyAudio Member Join Date: Jul 2004 Location: Netherlands	It is a pseudo push-pull design. At around 1969 it was difficult to make complementary transistors, so they designed (iron or no-iron) pseudo-pp amps, no need for expensive transistor-couples (and matching) Philips and others came with some of those designs. PP indeed eleminates 2nd order harmonics. The use of a triode in the first stage creates some even harmonics, all together the amp could sound very neutral due to the combination of "even" & "odd" stages. But i am unaware what the bootstrap will do to the harmonic distorsion., (bootstrap = positive feedback) __________________ Daisy Bell

15th September 2007, 05:34 PM	#25
smoking-amp diyAudio Member Join Date: Dec 2001 Location: Hickory, NC	The splitter bootstrap guarantees equal grid to cathode drive voltage on the top output tube. Since it references the equal voltage drop on the top 82K (versus the bottom 82K) splitter resistor to the top tube's cathode (which the bottom drive already does too). Since the splitter bootstrap is not increasing the top grid drive versus the bottom grid drive, it should not be creating any additional distortion here. Really just has the same effect as one would get using an interstage transformer with two floating secondaries. (Remind me not to buy any interstage transformers, how stupid!) Don __________________ Ohms Law V = I R

17th September 2007, 05:32 PM	#26
tubee diyAudio Member Join Date: Jul 2004 Location: Netherlands	Talking about interstage transformeres: had 2 identical ones with special mu core, one i demolisched as study-object, i am now sorry i did. Did some thinking to add a cap and a autotransformer, not easy with the bootstrap. __________________ Daisy Bell

15th September 2007, 08:13 AM	#21
woody diyAudio Member Join Date: Jan 2002 Location: Tyrone Ga. U.S.A.	I don't think this is single ended.

17th September 2007, 07:04 PM	#27
tubee diyAudio Member Join Date: Jul 2004 Location: Netherlands	Is this gonna work? __________________ Daisy Bell

17th September 2007, 07:15 PM	#28
tubee diyAudio Member Join Date: Jul 2004 Location: Netherlands	Little improvement, speaker on one side grounded __________________ Daisy Bell

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