Quad 306:Why has no driver in T9?.

GEirin · 16th April 2011, 10:27 AM

Hi all.
I need basic info of Quad 306 amplifier. I am interested in knowing how is the type of the output transistors. Why has no driver in T9?. I cant`really understand how it operaters in this particular model. Is it push pull class AB? So if anyone here could give me some info about this "strange" transistor implementation.
Thanks.

lineup · 16th April 2011, 10:35 AM

T8 is not really a driver for T10.
It is an inverter to fit signal to the N_Channel T10.
T9 does not need such an inverter transistor. It is in phase.

If T10 had been a P_Channel, then need no inveter.

GEirin · 16th April 2011, 10:36 AM

Quad- 306 output stage.

GEirin · 16th April 2011, 10:41 AM

Hi Lineup. Thanks.
My question. There are problems with different input impedances in the output transistors?

GEirin · 16th April 2011, 11:03 AM

Which is the funtion of R21 // L2?

Tajzmaj · 16th April 2011, 03:02 PM

Hi
306,529,606,707,909....are basically the same. They are kind of upgraded 405 current dumping design patented by quad.....Here it goes for small single ended class A amp followed by class C unbiased output stage or so called ,,dumpers,,...There is plenty of information available on net.
Those L and R helps to slow down negative side of c class stage to prevent oscillations, plus it probably cause some phase corrections....later it was added 1n cap to b-c of this same negative output transistor....
Best regards
Taj

GEirin · 16th April 2011, 03:38 PM

Hi Tajzmaj,
Then these paths are equivalent? In your opinion which is better: R//L (Quad 306) or R//C (Arcam A60)?

Tajzmaj · 17th April 2011, 12:47 AM

I'm not familiar with arcam.....but I checked complete circuit and it is completely different circuit topology. I never heard arcam so I can not compare those two amps. Sorry. But it looks like that both amps produce similar power. Arcam has good reputation and quad as well. I like quads, and have some of them myself. They are all good and reliable amps. But 306 is designed to power some small dynamic speakers. If you need it for something bigger than 606/707/909 is batter choice. Btw what are you intended to clone something or just asking.....?
And if you like some theory and other stuff about quads....
http://quad405.com/currentdumping.pdf
Quad 405 Information Page
Best regards
Taj

GEirin · 17th April 2011, 02:00 AM

Thank you very much for your response. I'm not interested in making a clone. If the justification for the quasi Quad configuration. I have an old amplifier (Philips 50W) output stage as the Arcam A60, and I was struck by the configuration of the Quad.
Best regards
Guillermo

16th April 2011, 10:35 AM	#2
lineup diyAudio Member Join Date: Dec 2005 Location: the north	T8 is not really a driver for T10. It is an inverter to fit signal to the N_Channel T10. T9 does not need such an inverter transistor. It is in phase. If T10 had been a P_Channel, then need no inveter. __________________ lineup

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Modding the Benz Micro PP1 T9	Zoodle	Analogue Source	1	6th January 2011 06:33 PM
Rebuilt Quad 306 channel but now buzzes	steevo	Solid State	0	30th April 2010 10:19 AM
Quad 306 Rebuild	steevo	Solid State	3	24th June 2007 09:56 AM
Quad 306 fault	steevo	Solid State	1	19th May 2007 05:27 PM
Quad 306 fault finding	harrygrey382	Solid State	4	14th February 2007 06:17 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

16th April 2011, 10:41 AM	#4
GEirin diyAudio Member Join Date: Jun 2004 Location: Mendoza	Hi Lineup. Thanks. My question. There are problems with different input impedances in the output transistors?

16th April 2011, 11:03 AM	#5
GEirin diyAudio Member Join Date: Jun 2004 Location: Mendoza	Which is the funtion of R21 // L2?

16th April 2011, 03:02 PM	#6
Tajzmaj diyAudio Member Join Date: Mar 2011 Location: Ljubljana	Hi 306,529,606,707,909....are basically the same. They are kind of upgraded 405 current dumping design patented by quad.....Here it goes for small single ended class A amp followed by class C unbiased output stage or so called ,,dumpers,,...There is plenty of information available on net. Those L and R helps to slow down negative side of c class stage to prevent oscillations, plus it probably cause some phase corrections....later it was added 1n cap to b-c of this same negative output transistor.... Best regards Taj

17th April 2011, 12:47 AM	#8
Tajzmaj diyAudio Member Join Date: Mar 2011 Location: Ljubljana	I'm not familiar with arcam.....but I checked complete circuit and it is completely different circuit topology. I never heard arcam so I can not compare those two amps. Sorry. But it looks like that both amps produce similar power. Arcam has good reputation and quad as well. I like quads, and have some of them myself. They are all good and reliable amps. But 306 is designed to power some small dynamic speakers. If you need it for something bigger than 606/707/909 is batter choice. Btw what are you intended to clone something or just asking.....? And if you like some theory and other stuff about quads.... http://quad405.com/currentdumping.pdf Quad 405 Information Page Best regards Taj

17th April 2011, 02:00 AM	#9
GEirin diyAudio Member Join Date: Jun 2004 Location: Mendoza	Thank you very much for your response. I'm not interested in making a clone. If the justification for the quasi Quad configuration. I have an old amplifier (Philips 50W) output stage as the Arcam A60, and I was struck by the configuration of the Quad. Best regards Guillermo

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)