Re: High neg. feedback ratio
Hello Francois,
If you like tube sound, try 2sk170 in the front stage.
Mihai
Francois G said:
Hello Francois,
If you like tube sound, try 2sk170 in the front stage.
Mihai
re, my amp result
Hi Mike,
I have a test on my amp with this specs:
2 channels; output device 1 pair of 2sa1216+2sc2922 each channel.
dual 48V; with 250VA transformer, rectifier caps: two dual 10,000/63v. The output device 2sa1216-c2922 is the best output device I've had which gave my amp a good, firm bass and a nice mid
a Heat sink with fan
Buffer preamp, +/-33v supply, and an input preamp. My pre-amp require a separate transformer. voltage regulator and 2 big capacitors (dual 10.000/50V) I have tests and found that such preamp is needed in order to give good amp sound.
The amp sound is great with, excellent bass vocal, great and lively performance with classical music, with clear, detailed sound. I reckon this is the best amp of mine.
The amp is bias at 100 ma for each output device, complement darlington (tip41+42) quiescent current: 75ma each. the First(input) and second stage quiescent current are 4 and 5,5ma respectively.
The heat sink is 50 Celsius degree when idle, get very hot at high volume where the amp begin to distort. The amp run with very high level for hours without any problem.
In fact at high volume, my power supply is exhausted, it drop to as low as 32V and the amp distort.
Hi Mike,
I have a test on my amp with this specs:
2 channels; output device 1 pair of 2sa1216+2sc2922 each channel.
dual 48V; with 250VA transformer, rectifier caps: two dual 10,000/63v. The output device 2sa1216-c2922 is the best output device I've had which gave my amp a good, firm bass and a nice mid
a Heat sink with fan
Buffer preamp, +/-33v supply, and an input preamp. My pre-amp require a separate transformer. voltage regulator and 2 big capacitors (dual 10.000/50V) I have tests and found that such preamp is needed in order to give good amp sound.
The amp sound is great with, excellent bass vocal, great and lively performance with classical music, with clear, detailed sound. I reckon this is the best amp of mine.
The amp is bias at 100 ma for each output device, complement darlington (tip41+42) quiescent current: 75ma each. the First(input) and second stage quiescent current are 4 and 5,5ma respectively.
The heat sink is 50 Celsius degree when idle, get very hot at high volume where the amp begin to distort. The amp run with very high level for hours without any problem.
In fact at high volume, my power supply is exhausted, it drop to as low as 32V and the amp distort.
re. thermal dispation
My heat sink: (20cm,12cm,2.5cm) with a 2-inch, 1.5w fan on top. In Idle stage its thermal dispation of about 36W (our average environment temperature 30 degree Celsius)
My heat sink: (20cm,12cm,2.5cm) with a 2-inch, 1.5w fan on top. In Idle stage its thermal dispation of about 36W (our average environment temperature 30 degree Celsius)
Then I understand you need a fan,😉 In my Sewa amp that puts out the same ammount of heat that yours I have 25x10x5cm heatsinks,without a fan,and they get HOT!
😉
😉re. amp result
ya. I think it's OK for amp at that temperature (70 C deg) because I have put my amp on that condition for a month and nothing fail. Actually it's so hot to touch the heat sink.😀 . At that condition the quiescent current reduce to some 50 ma, and I do not see any distortion yet.
ya. I think it's OK for amp at that temperature (70 C deg) because I have put my amp on that condition for a month and nothing fail. Actually it's so hot to touch the heat sink.😀 . At that condition the quiescent current reduce to some 50 ma, and I do not see any distortion yet.
Bias (DUMMY ALERT!)
Hi, Mike:
From reading through both the original and this thread I've gathered that the most linear operation of the sys-a-sym's output devices occurs when they're biased with a 24 or 25mv drop across an emitter resistor. Is this also true for the AAK version, using the Toshiba 2SC5200/2SA1943 pair? If so, and my heatsink won't handle that high a bias, are there certain bias points below 24/25mv that are better sonically than others?
Thanks.
George
Hi, Mike:
From reading through both the original and this thread I've gathered that the most linear operation of the sys-a-sym's output devices occurs when they're biased with a 24 or 25mv drop across an emitter resistor. Is this also true for the AAK version, using the Toshiba 2SC5200/2SA1943 pair? If so, and my heatsink won't handle that high a bias, are there certain bias points below 24/25mv that are better sonically than others?
Thanks.
George
At that bias point the dissapation/channel,at idle will be about 9-10w
and I think you can manage that,if not without a heatsink so a very small one,correct me if I´m wrong.🙂
re. bias
I think if the heat sink is barely enough in idle stage, how will it work. My amp measures 10 mv across output emiter (100ma quiescent) and every thing work nicely with moderate temperature. when I turn up the music it gets too hot and I have to install a fan. I have a version of symasym (with output 2sc5200/sa1943) distort at bias current 50ma, good at 85ma. When the bias is too low, I can see that the mid and treble is poor and noisy.
I think if the heat sink is barely enough in idle stage, how will it work. My amp measures 10 mv across output emiter (100ma quiescent) and every thing work nicely with moderate temperature. when I turn up the music it gets too hot and I have to install a fan. I have a version of symasym (with output 2sc5200/sa1943) distort at bias current 50ma, good at 85ma. When the bias is too low, I can see that the mid and treble is poor and noisy.
Re: Bias (DUMMY ALERT!)
you may find that the amp will operate well with the Vre reduced to 20mV or even as low as 15mV. But it should never fall below 15mV at any operating temperature. I tend towards the higher Vre when fully warmed up and on some amps this gives slightly more than 25mV when starting up from cold.
If your selected heatsink cannot keep the amp cool on quiescent current then it is not suitable for any speaker duty.
Hi,Colescuttle said:
you may find that the amp will operate well with the Vre reduced to 20mV or even as low as 15mV. But it should never fall below 15mV at any operating temperature. I tend towards the higher Vre when fully warmed up and on some amps this gives slightly more than 25mV when starting up from cold.
If your selected heatsink cannot keep the amp cool on quiescent current then it is not suitable for any speaker duty.
Thanks, Andrew.
I believe the sink will be more than adequate at idle, and probably will do fine under load. However, my small, from-scratch monobloc chassis are finished, and they were such a hassle to get right with hand tools that I wouldn't want to have to start over.
George
I believe the sink will be more than adequate at idle, and probably will do fine under load. However, my small, from-scratch monobloc chassis are finished, and they were such a hassle to get right with hand tools that I wouldn't want to have to start over.
George
Hi George,
Using On Semi MJW0281A and MJW0302A, I was able to run the SymAsym at around 23 mA bias current. This represented a low point in the low level distortion. I checked it at 20 KHz for the setting. Therefore, you could simply set it for 30 mA bias without worry for those devices. They are also extremely good sounding.
On Semi has discontinued those parts but they are available at Digikey I think. Newer MJW parts have been introduced. There are by far the best US power transistors ever! The same family extends to larger cases and dissipations.
-Chris
Using On Semi MJW0281A and MJW0302A, I was able to run the SymAsym at around 23 mA bias current. This represented a low point in the low level distortion. I checked it at 20 KHz for the setting. Therefore, you could simply set it for 30 mA bias without worry for those devices. They are also extremely good sounding.
On Semi has discontinued those parts but they are available at Digikey I think. Newer MJW parts have been introduced. There are by far the best US power transistors ever! The same family extends to larger cases and dissipations.
-Chris
Symasym PCB holes gauge & Riken
The answer is perhaps in the Gerber files but I have no way to read them, sorry.
For those who have already received the PCB's from Ryssen 1st run, I would like to know the drilling diameter of the PCB holes for the resistors (eg : 0.8 mm or 1.0 mm) ?
I have a stock of Welwyn resistors (MFR5) slightly oversized for the application (hence they will not heat !) but the connection leads diameter is rather high : 0.8mm and the body is 9mm in length.
I would like to know if they will physically fit.
Also I read somewhere in the forum that people have fitted Riken as input resistors (perhaps the 10R resistor R2 if I remember).
Your advice on such a choice ? Which resistors are worth being updated (name them from schematics please) ? And where one can still find no longer produced Riken resistors (perhaps pcX in Canada) ?
TIA for your help, like
many people from the 2nd run I have now launched the parts hunting !
The answer is perhaps in the Gerber files but I have no way to read them, sorry.
For those who have already received the PCB's from Ryssen 1st run, I would like to know the drilling diameter of the PCB holes for the resistors (eg : 0.8 mm or 1.0 mm) ?
I have a stock of Welwyn resistors (MFR5) slightly oversized for the application (hence they will not heat !) but the connection leads diameter is rather high : 0.8mm and the body is 9mm in length.
I would like to know if they will physically fit.
Also I read somewhere in the forum that people have fitted Riken as input resistors (perhaps the 10R resistor R2 if I remember).
Your advice on such a choice ? Which resistors are worth being updated (name them from schematics please) ? And where one can still find no longer produced Riken resistors (perhaps pcX in Canada) ?
TIA for your help, like
many people from the 2nd run I have now launched the parts hunting !
Hi Ryssen,
I am going to try the devices they do stock currently next, but I miss the MJW0281 and MJW0302 already.
-Chris
Good plan. Every thing I try them in has been a good experience. They aren't magic, but the matching is very good and they just work well.
I am going to try the devices they do stock currently next, but I miss the MJW0281 and MJW0302 already.
-Chris
OK
my question is somewhat complicated ...
I will ask MUCH simpler questions :
What is the EXACT size of the PCB we will receive from Ryssen ?
Is this the EXACT drawing of this PCB ?
http://www.diyaudio.com/forums/showthread.php?postid=1071852#post1071852
TIA, I will try to compute what Im looking for from yhe answers.
my question is somewhat complicated ...
I will ask MUCH simpler questions :
What is the EXACT size of the PCB we will receive from Ryssen ?
Is this the EXACT drawing of this PCB ?
http://www.diyaudio.com/forums/showthread.php?postid=1071852#post1071852
TIA, I will try to compute what Im looking for from yhe answers.
Hi hd38,
The PCB measures approx. 5.06" x 2.96", or in your part of the world approx. 128.5mm x 75.2mm.
Regards,
Al
The PCB measures approx. 5.06" x 2.96", or in your part of the world approx. 128.5mm x 75.2mm.
Regards,
Al
Thanks Al,
I will try to tune my printer to print a real size pattern and guess the part dimensions from that printout !
I will try to tune my printer to print a real size pattern and guess the part dimensions from that printout !
Re: Re: Re: Re: Thanks.
So pinkmouse ... there is some time in between. Do you have something at all left from this layout?
I am really fond of roeners two pair thermalTrak device symisym.
Eventually I have to do my artwork by myself. I have a license of Eagle, but it's most welcome to have something to begin on. This forum is the way to get it and to share your own arts. of different skills.
I am an old "readonly-lurker" here at this forum and when I first did a post this evening, I got a message that I'm under "moderation". I acn't even post messages to members yet 😀
pinkmouse said:
So pinkmouse ... there is some time in between. Do you have something at all left from this layout?
I am really fond of roeners two pair thermalTrak device symisym.
Eventually I have to do my artwork by myself. I have a license of Eagle, but it's most welcome to have something to begin on. This forum is the way to get it and to share your own arts. of different skills.
I am an old "readonly-lurker" here at this forum and when I first did a post this evening, I got a message that I'm under "moderation". I acn't even post messages to members yet 😀
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