DC serve in single class A power amp

audio-gd · 8th August 2008, 04:37 PM

These day I have built a single class A power amp, it only work for me, I ready buy a pair FOXTES F200A to it.
It use DC serve, so it don't need the coupling cap, and only have less than 2MV at output port.
The gain stage can drive the ZEN, but I love this output stage,it can built a 60W class A amp.But now I only built it output 35W/8R
it sound is clear but soft.

audio-gd · 8th August 2008, 04:38 PM

Photo

Mooly · 8th August 2008, 06:37 PM

Interesting circuit. I too use the single ended input configuraion-- sounds wonderful.
Not sure about the servo ? You have a lot of time constants in there. Do you not find they "fight" each other. I use just a single OpAmp and single cap to form the integrator.
Makes a nice change to see something a bit different

lineup · 8th August 2008, 09:20 PM

what output transistors you use?

audio-gd · 9th August 2008, 01:48 AM

Hi!Mooly:
The DC serve work well,
I use a dual OPA, the half is a integral amp, it can cut a lot of AC signal, but it will make a bit noise, so I use a 6DB fitter to cut the noise,
I ever to made three type DC serve ago, one is this, one is only a intergral amp, one is a intergral amp and a 12DB fitter amp, I like this.
If only use a intergral amp, match to this ,you can feel the only a intergral will have a bit "noise" in the music backdrop.

audio-gd · 9th August 2008, 01:52 AM

Hi!Lineup:
I use the C5200 only, the gain output stage use MJ11032/MJ11033, I take them work on 60MA , so it don't need extra drive transistor to output stage,
If add a drive transistor to output stage, the bass will burly, but I hope this amp have runny of bass.

lineup · 9th August 2008, 06:13 AM

- MJ11032/33 at 60 mA for voltage amp stage, VAS
- No predriver
- 2SC5200 = very good output transistors!
- All N-Channel output
- Single End Constant Current Class A

= Good Output stage amplifier.
----------------------
http://www.audio-gd.com/En%20audio-gd.htm
You make very good amplifiers, audio-qd

Regards Lineup

Mooly · 9th August 2008, 06:38 AM

Hi,
Would you say your amp "sounds" different---better, more musical than other configurations such as LTP input stage etc.

audio-gd · 9th August 2008, 07:04 AM

This amp open loop gain is 38DB, -3DB at 110K HZ,
At last, I use the cap of input is 1000P, it -3DB at 55KHZ,close loop gain is 27DB, I don't think wide frequency is better at single output class A,
I think , keep the frequency near tube amp, the sound mabey like tube amp.

audio-gd · 9th August 2008, 07:05 AM

Single output stage and manostat supply.

8th August 2008, 09:20 PM	#4
lineup diyAudio Member Join Date: Dec 2005 Location: the north	what output transistors you use? __________________ lineup

9th August 2008, 06:13 AM	#7
lineup diyAudio Member Join Date: Dec 2005 Location: the north	- MJ11032/33 at 60 mA for voltage amp stage, VAS - No predriver - 2SC5200 = very good output transistors! - All N-Channel output - Single End Constant Current Class A = Good Output stage amplifier. ---------------------- http://www.audio-gd.com/En%20audio-gd.htm You make very good amplifiers, audio-qd Regards Lineup __________________ lineup

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8th August 2008, 06:37 PM	#3
Mooly diyAudio Member Join Date: Sep 2007	Interesting circuit. I too use the single ended input configuraion-- sounds wonderful. Not sure about the servo ? You have a lot of time constants in there. Do you not find they "fight" each other. I use just a single OpAmp and single cap to form the integrator. Makes a nice change to see something a bit different

9th August 2008, 01:48 AM	#5
audio-gd diyAudio Member Join Date: Oct 2004	Hi!Mooly: The DC serve work well, I use a dual OPA, the half is a integral amp, it can cut a lot of AC signal, but it will make a bit noise, so I use a 6DB fitter to cut the noise, I ever to made three type DC serve ago, one is this, one is only a intergral amp, one is a intergral amp and a 12DB fitter amp, I like this. If only use a intergral amp, match to this ,you can feel the only a intergral will have a bit "noise" in the music backdrop.

9th August 2008, 01:52 AM	#6
audio-gd diyAudio Member Join Date: Oct 2004	Hi!Lineup: I use the C5200 only, the gain output stage use MJ11032/MJ11033, I take them work on 60MA , so it don't need extra drive transistor to output stage, If add a drive transistor to output stage, the bass will burly, but I hope this amp have runny of bass.

9th August 2008, 06:38 AM	#8
Mooly diyAudio Member Join Date: Sep 2007	Hi, Would you say your amp "sounds" different---better, more musical than other configurations such as LTP input stage etc.

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