SymAsaym as headphone amp
Hi,
I search for an "High End" solid state headphone amp.
I found two interesting projects:
a) a modified 15W Class A amp (Silicon Chip, Leo Simpson)
b) the SymAsym
For the power stage I want to use 2SA1930, 2SC5171 in Class A, driver BC337, BC327 - Class A, idle current adjusted for headphones, 2.2 .... 2.5 OHM instead of .22 OHM.
For PSU I will use the JLH ripple cleaner (a sugestion for those who want use a regulated voltage for the prestages). I found this in RockGrotto forum. I will reduce the voltage to +-15V
For the frontend and matched BJT's I have some in my stock, what are recommand?
LSK389A-TO71 (2 pcs) 1nV/hz Low Noise, Monolithic Dual, N-Channel JFET
LSK170A-TO92 (2 pcs) 1nV / hz Low Noise, Low Capacitance, High Input Impedance, N-Channel JFET Amplifier
IT124A-TO71 (2 pcs) Super Beta, Monolithic Dual, NPN Transistor
LS313A-TO71 (4 pcs) Tightly Matched, Monolithic Dual, NPN Transistor
LS352A-TO71 (4 pcs) Tightly Matched, Monolithic Dual, PNP Transistor
all from http://www.linearsystems.com/products.html
Hi,
I search for an "High End" solid state headphone amp.
I found two interesting projects:
a) a modified 15W Class A amp (Silicon Chip, Leo Simpson)
b) the SymAsym
For the power stage I want to use 2SA1930, 2SC5171 in Class A, driver BC337, BC327 - Class A, idle current adjusted for headphones, 2.2 .... 2.5 OHM instead of .22 OHM.
For PSU I will use the JLH ripple cleaner (a sugestion for those who want use a regulated voltage for the prestages). I found this in RockGrotto forum. I will reduce the voltage to +-15V
For the frontend and matched BJT's I have some in my stock, what are recommand?
LSK389A-TO71 (2 pcs) 1nV/hz Low Noise, Monolithic Dual, N-Channel JFET
LSK170A-TO92 (2 pcs) 1nV / hz Low Noise, Low Capacitance, High Input Impedance, N-Channel JFET Amplifier
IT124A-TO71 (2 pcs) Super Beta, Monolithic Dual, NPN Transistor
LS313A-TO71 (4 pcs) Tightly Matched, Monolithic Dual, NPN Transistor
LS352A-TO71 (4 pcs) Tightly Matched, Monolithic Dual, PNP Transistor
all from http://www.linearsystems.com/products.html
Re: SymAsaym as headphone amp
I think SYMASYM quite easily can be converted to JFET inputs. By using LSK389 (or matched SK170), you'll get "no" input bias currents and low DC offset, and then you don't have to use input or output capacitors = better sound, smaller amp, cheaper and no capacitor neurosis
. BC327/337 aren't the best sounding transistors. Why not use Toshibas or Sanyos as driver, or BC550/560?
If you want to take it a step further, try complementary feedback pair on the input and combine LSK389 with bipolars. You could also try cascoding both input and VAS.
Where can you get those transistors? They look very interesting.
FritzS said:
I think SYMASYM quite easily can be converted to JFET inputs. By using LSK389 (or matched SK170), you'll get "no" input bias currents and low DC offset, and then you don't have to use input or output capacitors = better sound, smaller amp, cheaper and no capacitor neurosis
. BC327/337 aren't the best sounding transistors. Why not use Toshibas or Sanyos as driver, or BC550/560?If you want to take it a step further, try complementary feedback pair on the input and combine LSK389 with bipolars. You could also try cascoding both input and VAS.
Where can you get those transistors? They look very interesting.
Re: SymAsaym as headphone amp
Hi FritzS,
Both would are excellent choices, but it sounds like you are leaning towards the a) option. As you may already be aware sandyK has all ready done pretty much what you want in his modified Class A preamp, except for the fet front end.
Having heard sandyK's systems on many occassions I can assure you he knows how to get excellent performanace from classic topologies using standard components.
I'm not sure if anyone has made a Symasym headamp yet, so there's a good challenge for you.
regards
Hi FritzS,
Both would are excellent choices, but it sounds like you are leaning towards the a) option. As you may already be aware sandyK has all ready done pretty much what you want in his modified Class A preamp, except for the fet front end.
Having heard sandyK's systems on many occassions I can assure you he knows how to get excellent performanace from classic topologies using standard components.
I'm not sure if anyone has made a Symasym headamp yet, so there's a good challenge for you.
regards
Hi Greg,
offtopic - I have the information about the 15 W class A from sandyK too. Gives there a thread about in diyAudio too?
It's only get the PCB from Australia (I live in Austria) is a hard and expensive way :-(
ontopic - I think you have information about the JLH "ripple eater" (or "ripple cleaner") too 🙂 I read about one want to use a regulator for the pre stages - the JLH "ripple eater" is a very good option! Search for "JLH ripple eater" and you will find more about ;-)
offtopic - I have the information about the 15 W class A from sandyK too. Gives there a thread about in diyAudio too?
It's only get the PCB from Australia (I live in Austria) is a hard and expensive way :-(
ontopic - I think you have information about the JLH "ripple eater" (or "ripple cleaner") too 🙂 I read about one want to use a regulator for the pre stages - the JLH "ripple eater" is a very good option! Search for "JLH ripple eater" and you will find more about ;-)
Re: Re: SymAsaym as headphone amp
The original 15W class A use BC327/337 ....... but which is the nearest Toshiba typ?
I get the LinearSystem samples from the local Austria distributor
http://www.ur-home.com/
http://www.bestelectronics.at/
You will find your local distributor here http://www.linearsystems.com/distributors_international.html
nelsonvandal said:
I think SYMASYM quite easily can be converted to JFET inputs. By using LSK389 (or matched SK170), you'll get "no" input bias currents and low DC offset, and then you don't have to use input or output capacitors = better sound, smaller amp, cheaper and no capacitor neurosis
If you want to take it a step further, try complementary feedback pair on the input and combine LSK389 with bipolars. You could also try cascoding both input and VAS.
Where can you get those transistors? They look very interesting.
The original 15W class A use BC327/337 ....... but which is the nearest Toshiba typ?
I get the LinearSystem samples from the local Austria distributor
http://www.ur-home.com/
http://www.bestelectronics.at/
You will find your local distributor here http://www.linearsystems.com/distributors_international.html
what for is the C6 cap used in symasym
I have a lot of noise when i use the C6 capacitor, without it everything goes silence.
C6 is that one parallel to resistor r26 with is connected emitters on both sides of drivers pair.
my transistors:
output stage: toshiba 2sc5200/2sa1943
drivers: toshiba 2sc5171/2sa1930
what dos that mean, bad transistors?
I know for sure that symasym can work in that configuration, with this transistors.
pleas help, its gets me nuts I cant resolve the problem.
I have a lot of noise when i use the C6 capacitor, without it everything goes silence.
C6 is that one parallel to resistor r26 with is connected emitters on both sides of drivers pair.
my transistors:
output stage: toshiba 2sc5200/2sa1943
drivers: toshiba 2sc5171/2sa1930
what dos that mean, bad transistors?
I know for sure that symasym can work in that configuration, with this transistors.
pleas help, its gets me nuts I cant resolve the problem.
Hi....sorry for my English, this is the second time when I post on this forum ... I have some questions about NORDIC schematic.... there are some components that I can't figure out what is there value....it's about C4,C15,C20,C21,R9,R25 and R21......thanks
Re: what for is the C6 cap used in symasym
That cap just rolls off the high frequency output above about 50kHz. I don't know why it should lead to oscillations. What kind of cap are you using in that position?
Sheldon
DoubleG@MDG said:
That cap just rolls off the high frequency output above about 50kHz. I don't know why it should lead to oscillations. What kind of cap are you using in that position?
Sheldon
hi Sheldon thanks for the replay.
I've used:
100nF MKP ERO/vishay
100nF MKS2 wima
120nF MKS2 wima
and all of this lead to noise only without cap everything goes quiet.
I've used:
100nF MKP ERO/vishay
100nF MKS2 wima
120nF MKS2 wima
and all of this lead to noise only without cap everything goes quiet.
Any of those should be fine. I have less experience with SS designs than tubes, and they are usually more complex. But I've built a pair of Symasym's on vero board and four more with PC boards. No major issues. Does the problem occur in one channel only?
Only thing I can suggest is to recheck all your part values, and look for any iffy solder joints. Also, check all the voltages.
Sheldon
Only thing I can suggest is to recheck all your part values, and look for any iffy solder joints. Also, check all the voltages.
Sheldon
My expressPCB Layout
I know that many people have already done layouts for this circuit, but I have been messing about with this layout for quite a while.
If anyone has the time, I would really appreciate a desk check of this layout before I send it off for etching.
It is in ExpressPCB format and is zipped so I can attach it to this forum.
I am really looking forward to building this amp.
Please let me know if I have totally screwed this up or what.
I know that many people have already done layouts for this circuit, but I have been messing about with this layout for quite a while.
If anyone has the time, I would really appreciate a desk check of this layout before I send it off for etching.
It is in ExpressPCB format and is zipped so I can attach it to this forum.
I am really looking forward to building this amp.
Please let me know if I have totally screwed this up or what.
Hate to double post, but the link above is borked due to spaces in the file name. Here it is again with underbars instead. Should be easier to download and open, etc...
By the way. the other major circuit on the board is the Very Simple Phono Stage by RJM. Discussion on that circuit is in the analog section.
By the way. the other major circuit on the board is the Very Simple Phono Stage by RJM. Discussion on that circuit is in the analog section.
This sunday i have installed the symassym (p2p) to work
and i found the "attack"...the speed, the slew rate and dinamics great while listening Bert Kaempfert musics.... recordings were made (the master) using tube equipment down the sixties....observe the quality, even into Youtube audio (not so good)...but see how old technology, tube sonics and vinyl were great.
How many recordings, digital ones, have this sonic quality.
Symassym amplifier show special qualities reproducing these musics you can listen into youtube.
Copy the adresses bellow, one by one into youtube adress bar and observe the audio quality.... TUBE recording folks....i love solid state...but we have to respect those old folks that made excelent studio recordings using Electronic tube equipment....boys!...down the sixties!!!
Please man!...in name of God.... oh dear... ... do not use those small PC speakers...plug your PC line out jack into your main amplifier and speakers..increase a little bass and treble (audibility for humans into low level) and enjoy old style good recording.
regards,
Carlos
and i found the "attack"...the speed, the slew rate and dinamics great while listening Bert Kaempfert musics.... recordings were made (the master) using tube equipment down the sixties....observe the quality, even into Youtube audio (not so good)...but see how old technology, tube sonics and vinyl were great.
How many recordings, digital ones, have this sonic quality.
Symassym amplifier show special qualities reproducing these musics you can listen into youtube.
Copy the adresses bellow, one by one into youtube adress bar and observe the audio quality.... TUBE recording folks....i love solid state...but we have to respect those old folks that made excelent studio recordings using Electronic tube equipment....boys!...down the sixties!!!
Please man!...in name of God.... oh dear... ... do not use those small PC speakers...plug your PC line out jack into your main amplifier and speakers..increase a little bass and treble (audibility for humans into low level) and enjoy old style good recording.
regards,
Carlos
Does anyone know where I can get a pair of PCBs to buy???
Or anyone selling a pair???
Thanks,
Lawrence
Or anyone selling a pair???
Thanks,
Lawrence
lawbadman said:
I have several boards, similar to the layout a few posts above. However, I have not yet built them out, so they are not proven, although they should be fine.
Let me know if you would like to build them out and give 'em a try.
Rather than start a new topic I shall post in here. Is the absolute maximum supply for Mike B's Symasym +/-36v? I ask because I need to change the transformer in my amp (it buzzes, possibly damaged core) and it would be very convenient if I could swap it for a +/-30Vac toroid I already have in another amp (I can then fit that amp with a new larger unit).
Amps built as per 5.3vers PCB, only running 8 ohm never 4 and 2sc5200 and 1943 output devices (0.4c/w heatsink per amp). Can the subsititute be done or would parts need changing, or is it just right out of the question?
Amps built as per 5.3vers PCB, only running 8 ohm never 4 and 2sc5200 and 1943 output devices (0.4c/w heatsink per amp). Can the subsititute be done or would parts need changing, or is it just right out of the question?
Have you used >=50V caps, throughout the assembly?
Try a couple of measurements for me.
Connect up the 30Vac transformer and measure the open circuit AC voltage. Check the mains supply voltage.
Connect the PSU with temporary smoothing caps and measure the open circuit DC voltage.
Connect the amplifier and check the bias current, if necessary reset to correct value.
Measure the voltage at the amp with the amp drawing nominally correct bias current.
Try a couple of measurements for me.
Connect up the 30Vac transformer and measure the open circuit AC voltage. Check the mains supply voltage.
Connect the PSU with temporary smoothing caps and measure the open circuit DC voltage.
Connect the amplifier and check the bias current, if necessary reset to correct value.
Measure the voltage at the amp with the amp drawing nominally correct bias current.
I have 50v caps on the PCB.
The 30Vac transformer is still installed in the other amp but since there's still no front panel I just stuck my probes in 😀 . Measuring +/-44Vdc with the amp powered up, it's a P101 so is about 30ma bias IIRC. The Symasym is a tad higher. Mains voltage I just checked is 250-255Vac, varying a bit but quite high I think.
The 30Vac transformer is still installed in the other amp but since there's still no front panel I just stuck my probes in 😀 . Measuring +/-44Vdc with the amp powered up, it's a P101 so is about 30ma bias IIRC. The Symasym is a tad higher. Mains voltage I just checked is 250-255Vac, varying a bit but quite high I think.