I can tell that yes and no, the version I'm talking about is made with genuine parts, I purchase form Digikey. Some small cap taken from old Japanese amp which is available at the junk yard.
Still I have another version with truly faked parts from China to make a comparison on prices and quality.
It's just for fun and I wanna know how fake technology from China is making progress. ha ha
Still I have another version with truly faked parts from China to make a comparison on prices and quality.
It's just for fun and I wanna know how fake technology from China is making progress. ha ha
he he of course I'm have a collection here of several type of faked output trans with same name. At first I break some of them apart to see the dye if it is good enough (in reference with the pics given by the forum on faked trans). And next some VA test (high voltage as high as 120V and current of some 3A continuous and peak 7A with device 2sc5200) then finally I will progress to my amp. With driver and pre-driver transistor, I always use genuine part for genuine parts' price is not go far from Chinese.
Moreover, By experimenting I also find that if the driver trans (C4793-A1837or B649-d669) were faked. Whatever genuine parts you put in to your amp it's useless.
In our country it's hard to have genuine parts, you can either have them at the junk yard, from the dead and buried old amp or from digikey. he he that's too bad for us.
Moreover, By experimenting I also find that if the driver trans (C4793-A1837or B649-d669) were faked. Whatever genuine parts you put in to your amp it's useless.
In our country it's hard to have genuine parts, you can either have them at the junk yard, from the dead and buried old amp or from digikey. he he that's too bad for us.
thanks Mike
I have found and eliminated the oscillation in my amp. She is much better now.
thanks indeed.
I have found and eliminated the oscillation in my amp. She is much better now.
thanks indeed.
I just omit the feedback compensation and the sound is better, deeper bass, sweet treble and the sound is no longer dry and lack of bass vibration.
It is very difficult to judge weather my amp oscillate in this case. All of my previous built amp oscillate madly by sinking Power and give out big hum or idle noise. this amp does not have any of these signs. Just abnormally bright sound. There must be a lot of noise in my brightness sound.
I think my Sym does work now.
Here I attached my final amp after changing the feedback network
It is very difficult to judge weather my amp oscillate in this case. All of my previous built amp oscillate madly by sinking Power and give out big hum or idle noise. this amp does not have any of these signs. Just abnormally bright sound. There must be a lot of noise in my brightness sound.
I think my Sym does work now.
Here I attached my final amp after changing the feedback network
Finally It cost me $35 for this version of 2 channels Symasym with faked outputs and $70 for a genuine one.
Now the listening test, I can find that the genuine sound better, especially at very high volume the but very few people recognized that. Of course the faked one dispate a lot of heat, because of the high bias (120ma per outputs) and high working temperature (greater than 50 degrees)
If I don't have a try I shouldn't have had such a cheap and nice amp.😎
Also I have also test the amps with my own voice, it really does put me on
Now the listening test, I can find that the genuine sound better, especially at very high volume the but very few people recognized that. Of course the faked one dispate a lot of heat, because of the high bias (120ma per outputs) and high working temperature (greater than 50 degrees)
If I don't have a try I shouldn't have had such a cheap and nice amp.😎
Also I have also test the amps with my own voice, it really does put me on
Here is my version of symasym with +/- 48V rail. I have use this amp for a year now.
Until now, this amp is very well behaved, and I like its sound, its bass and nice treble. I think this amp is very good for vocal reproduction.😎
Until now, this amp is very well behaved, and I like its sound, its bass and nice treble. I think this amp is very good for vocal reproduction.😎
Phong,
I've build the symasym 5.3 and curious about yr version
did you design your own pcb for sym asym?
if you don't mind can you post it here?
thank you,
I've build the symasym 5.3 and curious about yr version
did you design your own pcb for sym asym?
if you don't mind can you post it here?
thank you,
ya, I have design my own pcb and posted it some days ago in my recent post. Both of my symasym versions come from that pcb design with some customizations.
I also have a nice power supply, speaker protection and preamp module that coming along with this amp, but I haven't documented yet. I will post it soon
I also have a nice power supply, speaker protection and preamp module that coming along with this amp, but I haven't documented yet. I will post it soon
Other output transistor options?
Has any one built with the MJL21193 + MJL21194 combination? If so, what are your impressions?
Cheers,
Ryan
Has any one built with the MJL21193 + MJL21194 combination? If so, what are your impressions?
Cheers,
Ryan
Ryan, i have. These sound ... different. It's not perfectly my taste, but they sound somehow lovely/warm, absolutely not bad.
Be aware that the pair is MJL21194/21193, the 21194 is the npn.
PhongVuTuan, before releasing your design to the public, do intensive scoping, you must be sure that the amp is stable. Stabilizing an amp can be the toughest part of amp design.
Mike
Be aware that the pair is MJL21194/21193, the 21194 is the npn.
PhongVuTuan, before releasing your design to the public, do intensive scoping, you must be sure that the amp is stable. Stabilizing an amp can be the toughest part of amp design.
Mike
I have do it with 21194/93, and compare it directly with another Symasym with just other outputs (Toshiba 2sc5200). The Toshibas seems to be more dynamics than the Moto. I have increased the bias on the 21193/94 at about 150mA and they are my favorite now for HiFi, and the Toshiba for Home Cinema.
I think it depend of kind of speakers you are listening.
I think it depend of kind of speakers you are listening.
Yeah,
I have finished a newer version of symasym 4.1 described in my earlier post, but now I'd like to make it a powerful amp using 2 pairs of 2sc2922/SA1216;20,000mF/63V rectifier cap for per rail with A big power transformer weighing 8kg. The Power amp is running with +/-52V, predrive at +/-67V. I use separate rectifier for each channel.
The amp turn out to be the best of my amps till this time. The sound is very lively.
Although this amp is very powerful, the gain is quite low and I have to put on a buffer preamp with using OPA2134.
Finally, I have to adjust gain compensation circuit according to the type of output I'm using.
I have finished a newer version of symasym 4.1 described in my earlier post, but now I'd like to make it a powerful amp using 2 pairs of 2sc2922/SA1216;20,000mF/63V rectifier cap for per rail with A big power transformer weighing 8kg. The Power amp is running with +/-52V, predrive at +/-67V. I use separate rectifier for each channel.
The amp turn out to be the best of my amps till this time. The sound is very lively.
Although this amp is very powerful, the gain is quite low and I have to put on a buffer preamp with using OPA2134.
Finally, I have to adjust gain compensation circuit according to the type of output I'm using.
thank you Donk.
other views.
http://www.diyaudio.com/forums/showthread.php?s=&postid=1414253#post1414253
other views.
http://www.diyaudio.com/forums/showthread.php?s=&postid=1414253#post1414253
Making PCB , need approvals.
Hello,
This started with , making of DX HDII Clone PCB.
I suppose DX HDII is another version of symamym
symasym5
Can I contribute by making PCB available.
I will re-design the PCB layout, so that it would not conflict with original design.. and as per above mentioned website, it says:
I ask for permission to remake PCB, for symasym5.3 .
also need comments from HD DXII Authors on this.
Regards
suds
Hello,
This started with , making of DX HDII Clone PCB.
I suppose DX HDII is another version of symamym
symasym5
Can I contribute by making PCB available.
I will re-design the PCB layout, so that it would not conflict with original design.. and as per above mentioned website, it says:
I ask for permission to remake PCB, for symasym5.3 .
also need comments from HD DXII Authors on this.
Regards
suds
Oscillation or Not - Sysaysym
Hi All
I had taken the original symasym and designed a "Car amplifier" around it because I enjoyed the original so much.
The amp uses two sets of OP transistors and runs off +/- 42V, because I expected it to drive 2ohm loads as well. It sounded clean and detailed but about 2 weeks ago I noticed some distortion appearing from the speakers which seemed to fade a bit after warming up😕
I used a scope on the VAS section and noticed the attached waveform. The waveform measures 520mVpk.pk and the frequency was in the region of 266kHz. I tried different values for the stabilisation caps in the VAS thinking that driving 2 sets of OP devices could be causing the problem.... no luck. Changed the 22pF cap in the feedback line to lower values and slightly higher values (before it broke into huge oscillation)..... no luck here either.
The only time this "oscillation" dissappeared was when I removed the 2 x 22R base stoppers from the MJE* driver transistors effectively disconnecting the output stage. Please help as I do not wish to change values from the original without knowing what the consequences would be. 🙁
Hi All
I had taken the original symasym and designed a "Car amplifier" around it because I enjoyed the original so much.
The amp uses two sets of OP transistors and runs off +/- 42V, because I expected it to drive 2ohm loads as well. It sounded clean and detailed but about 2 weeks ago I noticed some distortion appearing from the speakers which seemed to fade a bit after warming up😕
I used a scope on the VAS section and noticed the attached waveform. The waveform measures 520mVpk.pk and the frequency was in the region of 266kHz. I tried different values for the stabilisation caps in the VAS thinking that driving 2 sets of OP devices could be causing the problem.... no luck. Changed the 22pF cap in the feedback line to lower values and slightly higher values (before it broke into huge oscillation)..... no luck here either.
The only time this "oscillation" dissappeared was when I removed the 2 x 22R base stoppers from the MJE* driver transistors effectively disconnecting the output stage. Please help as I do not wish to change values from the original without knowing what the consequences would be. 🙁
