Alan, please use the values for the MICAs as given in the schematic!
For example:
Read Pavel Macura's (forum's nickname: PMA) observations about the SYMASYM's tendency to oscillate when he uses Toshiba's 2SC5200 / 2SA1943 and a C9 value of 22pF.
(http://www.diyaudio.com/forums/soli...er-designed-michael-bittner-our-mikeb-77.html from post #767 on).
Decreasing the value of C9 to 3.3pF remedied his problem!
The values of the MICAs are essential.
In your case (the MJ21196 has a relatively high Cob of 500pF and a slow transistion frequency of 4Mhz) I would use the given 10pF value for C9.
Best regards - Rudi Ratlos
For example:
Read Pavel Macura's (forum's nickname: PMA) observations about the SYMASYM's tendency to oscillate when he uses Toshiba's 2SC5200 / 2SA1943 and a C9 value of 22pF.
(http://www.diyaudio.com/forums/soli...er-designed-michael-bittner-our-mikeb-77.html from post #767 on).
Decreasing the value of C9 to 3.3pF remedied his problem!
The values of the MICAs are essential.
In your case (the MJ21196 has a relatively high Cob of 500pF and a slow transistion frequency of 4Mhz) I would use the given 10pF value for C9.
Best regards - Rudi Ratlos
Gentlemen, I have sent you the NJW-SYMASYM's Builder's Manual and associated documents an hour ago and am currently listening to a pair of 10€ ebay - speakers connected to it (attached image).
The NJW-SYMASYM sounds beautifully, but I am having troubles (do no hear the slighest tone), when I try to connect it to pair of 1.000€ Mission 781 speakers.
My fault - as I suppose!
I will go on with this issue - Rudi_Ratlos
The NJW-SYMASYM sounds beautifully, but I am having troubles (do no hear the slighest tone), when I try to connect it to pair of 1.000€ Mission 781 speakers.
My fault - as I suppose!
I will go on with this issue - Rudi_Ratlos
Attachments
I have just received Rudi's documents.
It is not enough to say they are excellent. They are superb.
Rudi , we are in masterful hands , thank you.
It is not enough to say they are excellent. They are superb.
Rudi , we are in masterful hands , thank you.
Hi, Gentlemen,
I have measured and matched the NJW0281G / NJW0302G - output transistors on the last weekend.
The result is amazing:
You all will have pairs of transistors, the Hfe of which is within 1% !
Some of you (like my friend Harry, who did the proofread of the Builder's Manual) will have pairs that are even close to "cross-matched within 1%" (see image below)!
This is why I have chosen the NJW0 - transistors!
It is the best series of output-transistors that I have ever measured and matched!
Regarding my previous post: one of my Mission 781 - speakers is simply "dead".
I have swapped it between several of my amplifiers, but I it will not sing any tone!
I will therefore offer it on ebay as "defect".
Best regards - Rudi_Ratlos
I have measured and matched the NJW0281G / NJW0302G - output transistors on the last weekend.
The result is amazing:
You all will have pairs of transistors, the Hfe of which is within 1% !
Some of you (like my friend Harry, who did the proofread of the Builder's Manual) will have pairs that are even close to "cross-matched within 1%" (see image below)!
This is why I have chosen the NJW0 - transistors!
It is the best series of output-transistors that I have ever measured and matched!
Regarding my previous post: one of my Mission 781 - speakers is simply "dead".
I have swapped it between several of my amplifiers, but I it will not sing any tone!
I will therefore offer it on ebay as "defect".
Best regards - Rudi_Ratlos
Attachments
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Hi Rudi,
Thanks for the construction manual which is very helpful for people building the amp who do have an understanding of electronics.
You are doing a pretty good job for the community by organising the group buy etc.
Greets,
TrustinTech
Thanks for the construction manual which is very helpful for people building the amp who do have an understanding of electronics.
You are doing a pretty good job for the community by organising the group buy etc.
Greets,
TrustinTech
Gentlemen, I have received the NJW0-SYMASYM - PCBs a minute ago!
http://abload.de/img/snv32518ybs9e.jpg
The PCBs look magncifent - like a work of art!
I will assemble your orders on the weekend and send the letters / small parcels to you ASAP (next Monday).
Best regards - Rudi_Ratlos
P.S.: Those of you who requested the PCB to be cut: it will take some further days.
http://abload.de/img/snv32518ybs9e.jpg
The PCBs look magncifent - like a work of art!
I will assemble your orders on the weekend and send the letters / small parcels to you ASAP (next Monday).
Best regards - Rudi_Ratlos
P.S.: Those of you who requested the PCB to be cut: it will take some further days.
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Hi Rudi,
this is really good news and the PCBs look terrific!
I have changed my mind regarding the cutting. Is it possible to get the boards uncut?
Kind regards,
Michael
this is really good news and the PCBs look terrific!
I have changed my mind regarding the cutting. Is it possible to get the boards uncut?
Kind regards,
Michael
Thank you very much!!! 🙂
I am quite curious how the amps sound - can't wait to start soldering.
Michael
I am quite curious how the amps sound - can't wait to start soldering.
Michael
Get the irons warmed up
Box received, perfectly packaged.
Time to order the parts.
Thanks Rudy
Grtz
Bert
Box received, perfectly packaged.
Time to order the parts.
Thanks Rudy
Grtz
Bert
The PCBs look really great. But I have two questions:
1) Which screws should I use to screw the transistors on the heatsink/the PCBson the heatsink? M3s?
2) Which connector do you recommend on the PSU-PCB to connect the Speaker-Protection with the PSU?
1) Which screws should I use to screw the transistors on the heatsink/the PCBson the heatsink? M3s?
2) Which connector do you recommend on the PSU-PCB to connect the Speaker-Protection with the PSU?
Hi Rudi,
Fast and excellent than ever! Thank you very much!
But now i net a Pre Amp.
It is posible to get the "Versatile and comfortable passive pre-amp" PCB from you?
Regards
Thomas
Fast and excellent than ever! Thank you very much!
But now i net a Pre Amp.
It is posible to get the "Versatile and comfortable passive pre-amp" PCB from you?
Regards
Thomas
My stuff arrived today and the boards look lovely.
Many thanks to Rudi for the very smooth GB and the comprehensive documentation.
Robert
Many thanks to Rudi for the very smooth GB and the comprehensive documentation.
Robert
3 PCBs and components arrived this afternoon in Australia ! If I had a decent car I'd want it to look as cool as the PCBs. Black with gold trim, oh yeah.
Magic work Rudi!
Magic work Rudi!
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Paul, thank you for your compliments!
But please: do not put the SYMASYM-PCBs into any cabinet and look at them only! This is not what the PCBs are meant for!
Build them! The SYMASYM is one of the best-sounding amplifiers published in this forum!
Do it slowly, especially when you come to populate and solder the transistors that have to be mounted beneath the PCB!
And give your SYMASYMs a nice case!
The image below shows you the case of my "SYMASYM-integrated-amplifier".
Best regards - Rudi
But please: do not put the SYMASYM-PCBs into any cabinet and look at them only! This is not what the PCBs are meant for!
Build them! The SYMASYM is one of the best-sounding amplifiers published in this forum!
Do it slowly, especially when you come to populate and solder the transistors that have to be mounted beneath the PCB!
And give your SYMASYMs a nice case!
The image below shows you the case of my "SYMASYM-integrated-amplifier".
Best regards - Rudi
