P3A Comparison table ( long .... )

[thimios]

P3A

Oops! May be I am wrong. I found Motorola application note AN485 and there is square wave response for 50Hz, 1kHz and 10kHz. 50Hz square wave has the same falling top as thimios's P3A while 1kHz and 10kHz are level. AN485 has active VAS ccs and 10uF input cap, so it seems that falling top line on the square wave amp output is caused by some other mechanism.

Fortunately there will never be any music signal resembling 50Hz square wave.

Hi ivanlukic thanks for reply.
I have repeat many times that bass is strong and deep.
As in previus message mention i have examine some others amplifiers and scopes are the same in low frequences.
In last post ,second group scopes, pictures 2,3,4,5....shown out siglal exact Copy of inp.signal (the input and output on top of each other).
Now we have the theoritical ...applications note
Thanks for this.
Thimios.

 

[JOHN BALI]

Transistor combo?

Hi Thimios,
Look at this one
stereo board with big caps
left side will be modified & right side use the recommended parts.

I will play with the transistor combo
I just finish soldering all the part except few transistor & input caps.
I can change few parts if you ask & please why...

To Sakis do you want to give me the transistor combo that should I try?
I have some
MJL21193/4
MJL1302/3281
2SA1302-C3281 (maybe fake but survive used at +/-45VDC for a few years)
2SA5200-A1943
2SA1216-C2922

driver
2SA1837-C4793
2SA1930-C5171
MJE15032-33
BD139-140
B649-D669

VAS will be 2SA1209 or KSA1381

Or should I try it all
there will be so long... because I'm a slow builder

Regards

 

[thimios]

Hi Thimios,
Look at this one
stereo board with big caps
left side will be modified & right side use the recommended parts.

I will play with the transistor combo
I just finish soldering all the part except few transistor & input caps.
I can change few parts if you ask & please why...

To Sakis do you want to give me the transistor combo that should I try?
I have some
MJL21193/4
MJL1302/3281
2SA1302-C3281 (maybe fake but survive used at +/-45VDC for a few years)
2SA5200-A1943
2SA1216-C2922

driver
2SA1837-C4793
2SA1930-C5171
MJE15032-33
BD139-140
B649-D669

VAS will be 2SA1209 or KSA1381

Or should I try it all
there will be so long... because I'm a slow builder

Regards

Nice work John looks beautiful.
Keep in mind in other version position led and transistor thermal coupled.
I can't say other comments because i can't see your pcb.

 

[thimios]

P3A

I can't say I've ever tested an amp with a square wave at such low frequencies so I don't know if it is a problem or not. I tend to use the square wave from my scope because it's so clean whereas my variable frequency signal generator is not that great but does let me measure gain as a function of frequency. Once I did use a square wave at 20KHz and it fried the amplifier. I read a bit about the stupidity of what I did and that there may be little value in testing at such high frequencies with square waves so I don't do that anymore. From what you are saying, it sounds like it is not a problem. Does the amplifier sound good - yes? - then there's no problem

Thanks for reply Bigun.
Yes this amplifier sounding good and have good measurements.
Testing an amplifier with square wave at high frequencies and high levels is a risk.
Post#370 last picture ....8W RMS /100KHz.
I has test this amplifier in full power (20V RMS /8R) at 70KHz and only part that destroyed is fuse.
Unfortunatly i haven't picture from this test and i can't repeat this.

 

[JOHN BALI]

Thimios,
do your finish your second board?
So you can hear a stereo set.
I won't share pcb layout but ok if only top side of the board
(the bottom don't look so good )

Regards

 

[thimios]

Thimios,
do your finish your second board?
So you can hear a stereo set.
I won't share pcb layout but ok if only top side of the board
(the bottom don't look so good )

Regards

Ha ha....second board.....no....in my cace second board is something uncommon.
Now i start DX Super A.http://www.diyaudio.com/forums/solid-state/221741-dx-blame-st-together-dx-super-114.html
LOOK POST#1136

 

[east electronics]

hello Guys been away for a while have we solved the trouble ?
@John bali
A very clever pcb marvelous id say

The semis under question are to many to comment
21193 never tested by me 1302-3281 sounded better than 1943-5200
BD139-140 left them behind me long time ago
B649-D669 never tested
MJ 150XX series its a yes when it comes to how rugged but a huge NO when it comes to sound issues unless you are in the hard rock business

Kind regards
Sakis
2SA1837-C4793
2SA1930-C5171 drivers did fine but still i think that BD829-830 was better

 

[JOHN BALI]

hello Guys been away for a while have we solved the trouble ?
@John bali
A very clever pcb marvelous id say

The semis under question are to many to comment
21193 never tested by me 1302-3281 sounded better than 1943-5200
BD139-140 left them behind me long time ago
B649-D669 never tested
MJ 150XX series its a yes when it comes to how rugged but a huge NO when it comes to sound issues unless you are in the hard rock business

Kind regards
Sakis
2SA1837-C4793
2SA1930-C5171 drivers did fine but still i think that BD829-830 was better

Thanks Sakis,
Your comment are more than enough to give me some view
now I have a better feeling that this one gonna be a good sounding one.
So I will try what you suggest & also will try that which never test too,
but the BD829-830 are not available here.
I like the insulated driver so it easier to mount on heat sink
This will be a bit longer cos I can't made it fast.

Best Regards
John

 

[fotios]

Still for my application i choose to go for smaller ( in physical size ) parts often large parts become microphonic and actually ""pick up"" things on the way especially in boards with some complexity like the ones you use worst when the board features zobel on it ( my intetntion is to zobel the amp outside the board ) and even worst with long ground traces .

Absolutelly correct remarks. Bravo Sakis.

 

[east electronics]

Fotios .... honored by your presence here....

I wish things are doing just fine for you in northern Greece

Kind regards
Sakis

 

[ashok]

......... but still i think that BD829-830 was better.......

The Ft of the BD 829 is quoted at 250 Mhz and the 2SC5171 appear to be 200 Mhz. Gain is also similar. Maybe the capacitance specs are different. Didn't see them on the data sheet for the BD series.
What makes the BD829 sound better ?

Maybe be more than just type numbers. Possible that the specs of the BD829 was at the upper end of the range than the 2SC device hence making it better !

 

[east electronics]

I actually don't know It will have a lot to do with the physics of how its made . One thing that i think is important is that the 829-30 combo is rated in lower voltage while preserves all the other characteristics like ft .

Running semis as close is possible to the operating voltage will produce a better result but also stress the semi

Kind regards
Sakis

 

[Bigun]

Sakis,

I'm not sure how higher voltage produces a better results so I was wondering what you thought is the physics for this ?

I am thinking a) higher voltage reduces influence of Early effect, b) often higher voltage reduces intrinsic capacitances by widening depletion layers

 

[east electronics]

Hi Thimios,
Look at this one
stereo board with big caps
left side will be modified & right side use the recommended parts.

I will play with the transistor combo
I just finish soldering all the part except few transistor & input caps.
I can change few parts if you ask & please why...

To Sakis do you want to give me the transistor combo that should I try?
I have some
MJL21193/4
MJL1302/3281
2SA1302-C3281 (maybe fake but survive used at +/-45VDC for a few years)
2SA5200-A1943
2SA1216-C2922

driver
2SA1837-C4793
2SA1930-C5171
MJE15032-33
BD139-140
B649-D669

VAS will be 2SA1209 or KSA1381

Or should I try it all
there will be so long... because I'm a slow builder

Regards

John ..

Please let us know if and when you are done with the pcb .
It is something that bugs me with your pcb . I think that a design like that will have a poor pssr even though it looks extremely neat .

Kind regards
Sakis

 

[JOHN BALI]

Ok, ... today I'll power it up.
I have option too to cut it into two mono blocks but not cut it now
to see what happen with this board.
Give me some hour...

Regards

 

[kp93300]

Hi John
I an interested to hear your experience between the LC VSSA and the P3A in terms of sound difference.
cheers

kp93300.

 

[thimios]

p3a

Ok, ... today I'll power it up.
I have option too to cut it into two mono blocks but not cut it now
to see what happen with this board.
Give me some hour...

Regards

I want to know too.
Vssa is my next project so i want to know your opinion about this COMPARISON.

 

[Cantunes]

I want to know too.

 

[east electronics]

I can Guess ..but will have to wait ...
Kind regards
Sakis

Nikos is another Happy builder we are expecting his comments soon and as far as i know he has been already working with VSSA

 

[Bigun]

These are very different amplifiers. The VSSA has higher OLG and lower distortion, it is symmetrical and will have low 2nd harmonic when you turn it up. The P3A has an asymmetric design for the front end and it will have dominant 2nd harmonic with higher overall THD. Depending on the the kind of music you may prefer either - I too am interested to hear how the difference is perceived.