which Amp Design Do you prefer between these two Design?

[Shahriar]

Hi
I Can not select between these two Elektor PA designs.
One (titan 1999) is a current feedback amplifier: Schematic here:
http://www.corradodriver.de/HTML/Elektronik/Gigant2000/Gigant1.htm

The Other One is a Voltage one Which I have attached the schematic (2005):

Pleas take a look at the two Measured Parameters. Do not pay attention to output
Power (It is not important to me 30W is enough for me).

The Only advantage of Titan Amplifier is Slew rate =170 while the other One is 18
Does it have great effect on Details?

After All, WHich One would you select? Please Do not Disscuss about Current Feedback topology Vs Voltage Feedback.
Which One do you choose, Why?

http://www.4shared.com/file/12522249/94ff3054/PA_Comparison.html
http://www.4shared.com/file/12522383/d95dfc71/2005_Schematic.html

ThanX in advance
Shahriar

 

[AndrewT]

Hi,
gigant 1 =2kW but you ask us to ignore this and comment on 30W quality!

r8,9,10,11 look like the NFB components. Why do you think this is current feedback?

Mixed AC and DC coupled then uses servo to correct the input offset error. Weird!

 

[thanh]

I prefer dual differential design to CFB design. Additional, I have no high power need
Have you ever view this design ? http://www.littlefishbicycles.com/poweramp/index.html
There is the only stage which is not diffential one. So I guess that it sounds very "detaily", "clean"

 

[consort_ee_um]

Shariar,
For me the question is: does that complexity buy you anything in terms of performance? What do you get above say a blameless amplifier?
In trying to answer your questions on the Gigant I have learnt about Accuphase circuits for which I thank you. But you pose a difficult question.

 

[Leolabs]

The CFB one is quite complex,should go for the VFB one.

 

[AndrewT]

The CFB one is quite complex,should go for the VFB one.

Leolabs,
is it CFB?

 

[Bonsai]

The Titan (=Gigant) was CFB - I read the original article and they discussed this point in some depth.

If its 30watts you want, go for the simpler VFB design. I doubt that the difference in slew rates will take the enjoyment out of your music!

Be warned - Elektor designs always had good measurements . . . but I think they sailed close to the wind in terms of phase margin so there have been many stories about instability - some people have no probems, others have problems. By the way, on the Titan, the article warned about sticking to the construction details strictly to avoid instability problems.

Another, much simpler option is to go for a gainclone.

Good luck with your project.

 

[AndrewT]

gigant 1
r8,9,10,11 ..... the NFB components.

Have I identified the NFB components correctly?
They look like a conventionl VFB loop from output to inverting input (the emitters) and ground.

Comments, since I cannot read the original article.

 

[PhongVuTuan]

re. Amp preference

Hi Thanh,
Nice 2 see you in this thread. Do you remember me??
I'm so curios about you. And really amazing to see your posts.
I came across your post in choosing a suitable design to build. I have some points here. Did you hear some body tell about Amp sound is determined by the components( transistors, OP, signal track capacitors). I found it right in my situation. I have made a Symasym amp with 4 range of power trans and they sound differently:
Power rail: +/-52V
- 2pair of 2sb688;D718/a channel ; bass a little bit loose
- 2pair of 2sc3281 and its counter part/a channel: better bass
- 2pair of Genuine Toshiba 2sc5200 - 2sa1943/ a channel: Clean and clear sound, firm bass
- 2sc2922-2sa1216 firmest bass of all.
I have test all these with classical music and the sound is good enough. I have made 4 variants of symasym and found this design good.

Also I have built some amp with destroyer X amplifier design and found it's nice with genuine parts. An amp with +/- 50V rails 2x10,000mf capacitor and a pair of 2sc5200+2sa1943 drive a 600w (dual 10" woofers) speaker shake my coffee cup. Very impressive

Did you have a look at some Rotel design. I have find a very interesting thing in their design that makes quality.

Now I have a try on a more differential approach and did not find a clue yet. Surely, there will be some more oscillation to cope with. I will tell you when I find smt.

 

[PhongVuTuan]

HI To Thanh

Hi Thanh,
Nice 2 see you in this thread. Do you remember me??
I'm so curios about you. And really amazing to see your posts.
I came across your post in choosing a suitable design to build. I have some points here. Did you hear some body tell about Amp sound is determined by the components( transistors, OP, signal track capacitors). I found it right in my situation. I have made a Symasym amp with 4 range of power trans and they sound differently:
Power rail: +/-52V
- 2pair of 2sb688;D718/a channel ; bass a little bit loose
- 2pair of 2sc3281 and its counter part/a channel: better bass
- 2pair of Genuine Toshiba 2sc5200 - 2sa1943/ a channel: Clean and clear sound, firm bass
- 2sc2922-2sa1216 firmest bass of all.
I have test all these with classical music and the sound is good enough. I have made 4 variants of symasym and found this design good.

Also I have built some amp with destroyer X amplifier design and found it's nice with genuine parts. An amp with +/- 50V rails 2x10,000mf capacitor and a pair of 2sc5200+2sa1943 drive a 600w (dual 10" woofers) speaker shake my coffee cup. Very impressive

Did you have a look at some Rotel design. I have find a very interesting thing in their design that makes quality.

Now I have a try on a more differential approach and did not find a clue yet. Surely, there will be some more oscillation to cope with. I will tell you when I find smt.

Further more, you are refering to a mosfet amp. I notice that fets are not OK with linearity, especially mosfet. They are not prescribe for audio amp until recently. You will have to choose carefully which type to use.

good luck with your new designs.

 

[thanh]

Hi PhongVuTuan!
If my mind is not wrong, amplifier_guru said that " VAS have a high gain and a lot of noise will destroy space of sound...."
Differential VAS has a big gain but CMRR is also high.

 

[PhongVuTuan]

re thanh thanh

Now I got the reason why you like differential approaches. In some instances you are right.

I think that the attached schematic is a class A amp. The other reference is a big amp with a new idea to heighten transistors characteristics.

Now you can type 2sc2922, and search image on google, you will find a more differential amp circuit.

I don't mean to talk you other wise, just go ahead with your approach and you will see very soon why are people don't prefer differential and why there exits a DestroyX amp. Now I will stop my coverage here.