Symasym5 modifid circuit

space2000

Member
2008-03-08 2:11 pm
hi, i am not good in electronics as all of you. i need help for this circuit design. at first i got it from Symasym5 then went to pavel site to have this modofied circuit design. i have build it. now i have modified by adding one more power transistor 2sc5200 and 2sa1943. i circled the design. do you think it is correct way to adding power transistor in parallel? i have posted the pic.


thank you.

myversion.jpg
 

DVBjunky

Member
2006-12-30 2:01 pm
Hi,

may I ask why do you not building the symasym designs of MikeB, AAK, Pavels Mod or others?

I did build several symasyms with Onsemi and Toshiba Transistors based on the "ready for build" design of these people.

Believe me....the only design with better audio quality but less power output is Roenders Amp (heavy modification of the symasym with other design elements).

A well build symasym with MJL 4281 or NJL 0281 will beat any "commercial non-DIY amp" up to the 2000 Dollar price tag.

But, if you want to another "mod", well......I just tried to avoid unnecessary work.

best regards

Alan
 

space2000

Member
2008-03-08 2:11 pm
amp question

hi, thank you for your comments.

actually here in singapore not easy to find those MJL 4281 or NJL 0281 parts. so i used 2sc5200, i know it is not good as those mjl. here is easy to find 2sc5200 and cheap too...only $8 a pare. this is the reason i used this. i am not good in amplifier or electronics, but i like those are hi class amp. honestly tells you, i had one amp that was pioneer, now not working. i used that casing and heat sink to buid one amp. the sound is good but i wanted to use more power to bost my speaker.

i am not so familier with those amplifier. just few days ago started to search to build my own a hi end amp thats all.


thank you.
 
This is a bipolar design. Depending on your choice of driver transistors and their idling currents, you may run out of base current in demanding situations.

If the driver heatsink is up to it, you can crank up the current, however you should know what you're doing ;-)

I'm sorry that I cannot give you more details as I'm do not know the Symasym well enough.

All the best, Hannes
 
OnSemi branch on SG

quote :

hi, thank you for your comments.

actually here in singapore not easy to find those MJL 4281 or NJL 0281 parts. so i used 2sc5200, i know it is not good as those mjl. here is easy to find 2sc5200 and cheap too...only $8 a pare. this is the reason i used this. i am not good in amplifier or electronics, but i like those are hi class amp. honestly tells you, i had one amp that was pioneer, now not working. i used that casing and heat sink to buid one amp. the sound is good but i wanted to use more power to bost my speaker.

i am not so familier with those amplifier. just few days ago started to search to build my own a hi end amp thats all.

thank you.


As far as I Know there is a branch of Onsemi on Singapore. Have you tried them ?

Here the web : http://www.onsemi.com/PowerSolutions/locateSalesSupport.do?countryCode=SGP

and Here is the address :
ON Semiconductor
25 Serangoon North Ave 5
#03-10 Keppel Digihub , Singapore 554914
65-6555-8260 (tel)
65-6482-4794 (fax)

Because I also hope that someone can find NJL0281D in SG...
 
Space2000, the extra pair is added correctly. But, the sc5200 are also tough devices (if genuine). Unless you plan to drive ugly <4ohm speakers and/or increase supply voltage above +/-36v, you can go with a single pair.

Andy, the Toshibas sound absolutely fine. But in my taste the MJL(W)0281/0302 sound even better. I haven't heard the mjl4281 yet.

Mike
 
DVBjunky said:
Hi,

I did build several symasyms with Onsemi and Toshiba Transistors based on the "ready for build" design of these people.

A well build symasym with MJL 4281 or NJL 0281 will beat any "commercial non-DIY amp" up to the 2000 Dollar price tag.

Alan

Hi,

I build the original Symasym with MJL3281A/MJL1302A, another one is a revamp of an old Parasound HCA-800II to a Symasym variant using 2SC5200/2SA1943, +/-50V from the existing power supply.

They sound quite different even though they shared the same circuit skeleton. It is like some girls are pretty and some are not but equally attractive though they eat the same food.

The 5200 has stronger bass, whereas for 3281, the treble is more refined. You have to try out to see which one suit you;)
 

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Re: power supply

space2000 said:
hi, my transformer have three line out, which i can get easily +v, -V and gnd but my power supply only 34-0-34. how can i get higher volatge like 68v with -v, +v and gnd?

if we add 34+34 then should be 68v but amplifier need +v,-v and gnd.
thank you.
Hi Space,
I think you are describing a centre tapped 68Vac giving 34-0-34Vac.

If you want more voltage then buy a higher voltage transformer.

The 68Vac CT will give about +-50Vdc.
 

space2000

Member
2008-03-08 2:11 pm
answer

hi,

andrewT thanks for your info. i think, for higher voltage, i have to get an another transformer.

amplifier, MJW0281 sound sweet, wow it is great. i just checked in farnell for availablity, can't find there. may b not easy to find here in singapore.

how much it cost you?

thank you.
 

space2000

Member
2008-03-08 2:11 pm
adding more transistor

hi,

i am just wondering, i have added one more 2sc2500 meanse 2sc5200 2pcs and 2sa1943 2 pcs, what is the power of my amp now? my voltage is +-34 dc.

if i add more transistor and operate -+34v dc will it be declining the sound quality? like luxman used 4 pare of 2sc5200 each chanel.

i don't know if the wats goes high or the depth of the sound will be change.

thank you..
 

roender

Member
2006-09-11 1:38 pm
MikeB said:
The power will not really increase by adding more output devices. And it is likely that you reduce sound quality.

Mike

Only if output BJTs are not well matched for Vbe and hfe.
Once matched, the sound quality are better than the same amplifier with only one output pears, because of more classA current for normal listening levels.
 

DVBjunky

Member
2006-12-30 2:01 pm
MJW 0281 are no longer available from OnSemi but just take the NJL 0281 - its an MJW in a slight smaller package and 2 additional PINs for Thermaltrak.

For use in the symasym you have to twist 2 Legs because of the slight different PINs. Several User of the german Analog Audio Forum (AAA) successfully used it in symasyms projects.

I sold my MJL4281-Symasym in February and now I am building a NJL0281-Symasym.

Check the Datasheets - the MJW0281 and NJL 0281 are identical DIEs. Use the Samples programm of OnSemi...dont forget to get the complementary NJL0302 transistors too.

Have fun.