Bailey 30W amplifier- new transistors

john_ellis · 5th March 2008, 09:50 PM

Bailey's 30W amplifier had an excellent performance for 1968!
None of the transistors are now available, but I think that there are some very close alternatives that might be as good.

Anyone considered trying that amp?

Proposed new line up

Original Replacement
MJ481 BD911
MJ491 BD912
40361 BD139
40362 BD140
BC125 BC337
BC126 BC327
BC107 BC237

The BD911 has very slightly higher power dissipation compared with the original MJ481 (90W instead of 87.5) and better Is/b. fT is almost as good (3 MHz instead of 4) and gain is higher (min. 15 @5A compared with 10 min at 3A.

cheers
John

Jan Dupont · 6th March 2008, 03:27 PM

Do you have the schematic ?

john_ellis · 8th March 2008, 10:51 PM

Hi Jan

It has been "published" on this forum somewhere as a Bailey.rar file, but I don't have permission to reprint the circuit, maybe you can email me.

cheers
John

Jan Dupont · 9th March 2008, 05:45 AM

Hi John,
Not easy to email you, when you haven't activated your forum email

Bone · 9th March 2008, 11:02 AM

Jan, I'll send you the article off list.

Tony.

Jan Dupont · 9th March 2008, 11:04 AM

Do that Tony

Bone · 9th March 2008, 11:17 AM

E-mail on its way. Attachment is rather large at 1M - hope thats not a problem.

Tony

5th March 2008, 09:50 PM	#1
john_ellis diyAudio Member Join Date: Sep 2006	Bailey 30W amplifier- new transistors Bailey's 30W amplifier had an excellent performance for 1968! None of the transistors are now available, but I think that there are some very close alternatives that might be as good. Anyone considered trying that amp? Proposed new line up Original Replacement MJ481 BD911 MJ491 BD912 40361 BD139 40362 BD140 BC125 BC337 BC126 BC327 BC107 BC237 The BD911 has very slightly higher power dissipation compared with the original MJ481 (90W instead of 87.5) and better Is/b. fT is almost as good (3 MHz instead of 4) and gain is higher (min. 15 @5A compared with 10 min at 3A. cheers John

6th March 2008, 03:27 PM	#2
Jan Dupont diyAudio Member Join Date: Apr 2003 Location: Copenhagen, Denmark	Do you have the schematic ? __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com

9th March 2008, 05:45 AM	#4
Jan Dupont diyAudio Member Join Date: Apr 2003 Location: Copenhagen, Denmark	Hi John, Not easy to email you, when you haven't activated your forum email __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com

9th March 2008, 11:04 AM	#6
Jan Dupont diyAudio Member Join Date: Apr 2003 Location: Copenhagen, Denmark	Do that Tony __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com

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8th March 2008, 10:51 PM	#3
john_ellis diyAudio Member Join Date: Sep 2006	Hi Jan It has been "published" on this forum somewhere as a Bailey.rar file, but I don't have permission to reprint the circuit, maybe you can email me. cheers John

9th March 2008, 11:02 AM	#5
Bone diyAudio Member Join Date: Jun 2004 Location: Dorset, UK	Jan, I'll send you the article off list. Tony.

9th March 2008, 11:17 AM	#7
Bone diyAudio Member Join Date: Jun 2004 Location: Dorset, UK	E-mail on its way. Attachment is rather large at 1M - hope thats not a problem. Tony

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