Liliya,
You have a rail to rail voltage of more than 180V so a transistor should be able to withstand at least this voltage.
The ones you chose now will do the job much better but don't have a safety margin voltage wise. They have a lot of power but a bit high Cob. Do you have a small heatsink for them? Do they run hot without?
Btw: My recommendation would be the SA1381/SC3503. They seem to be quite popular here at the moment. I used them in my amp that is very similar to the Goldmund.
Btw: Do you still have DC offset at the output jumping around? This concerned me a bit.
Good luck
You have a rail to rail voltage of more than 180V so a transistor should be able to withstand at least this voltage.
The ones you chose now will do the job much better but don't have a safety margin voltage wise. They have a lot of power but a bit high Cob. Do you have a small heatsink for them? Do they run hot without?
Btw: My recommendation would be the SA1381/SC3503. They seem to be quite popular here at the moment. I used them in my amp that is very similar to the Goldmund.
Btw: Do you still have DC offset at the output jumping around? This concerned me a bit.
Good luck
parts....
Maybe this will help for some members who is looking for parts...
I ordered from UTSOURCE.NET
2n5565 $15 each.
Bss71,74 $5 each.
shipping was $10.
Maybe this will help for some members who is looking for parts...
I ordered from UTSOURCE.NET
2n5565 $15 each.
Bss71,74 $5 each.
shipping was $10.
Attachments
I have seen this source before. My opinion is that they are Chinese counterfeit. They may or may not work properly.
>I have seen this source before. My opinion is that they are Chinese counterfeit. They may or may not work properly. <
Thanks for your advice
Thanks for your advice
......some parts have not arrived yet....🙁
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so amazed a thread about what appears to be such a small thing. in my experience a lot of designers do noy treat the mossies the field effect devices they are treat them as solid state valves. a good stable class A driver with reasonable biasing ie not the very badly utilised "Hitachi circuit" which is always used wrongly if it dont burn your skin its not "hot" enough bias wise, mosfet gates like current to charge or discharge effectively too many treat them as pure voltage devices too much
I read this ten times now and didn't get what you mean. Maybe use some punctuation marks.
Alex, it seems like you didn't use 2n5565. What FET did you use on your input stage?
Hi Alex,
Looks like you are binding 2 pcs of Jfets with a shrinking tube. Nice try. Can you tell us what are they? Anxious to see how you can come up with it.
Looks like you are binding 2 pcs of Jfets with a shrinking tube. Nice try. Can you tell us what are they? Anxious to see how you can come up with it.
.... so I replaced it with 2SK170 mached , I will see how it's working , but it's an long way until I will start this channel .🙂
Alex.
Alex.
I don't know where Charlie is from, but that is not "english".
And there is no extra information in his/her profile to enable us to help with his/her problem.
I am just waiting for the oppertunety for Roar and me to do serious tests the coming week.
Lee Knatta: The drivers you suggested (2SA1381/2SC3503) was not available at my supplier. Instead, I went for MJE 340/350. This is 300 V types.
Yes, offset setting also worries me a bit in that it is so unstable: Variation on both channels from 0 to 60 mV. Results like 0 - 5mV has been very common on amps I've previously built. But I see that the diversity I experience, is big, even if 60 mV does not represent any "danger ". Anybody have any suggestions for a "cure"?
I also had problems understanding what Charlieb99 tried to tell us. Did he mean that the FETs were to be run harder / increased the gain to bring up the temperature?
Eivind Stillingen
Lee Knatta: The drivers you suggested (2SA1381/2SC3503) was not available at my supplier. Instead, I went for MJE 340/350. This is 300 V types.
Yes, offset setting also worries me a bit in that it is so unstable: Variation on both channels from 0 to 60 mV. Results like 0 - 5mV has been very common on amps I've previously built. But I see that the diversity I experience, is big, even if 60 mV does not represent any "danger ". Anybody have any suggestions for a "cure"?
I also had problems understanding what Charlieb99 tried to tell us. Did he mean that the FETs were to be run harder / increased the gain to bring up the temperature?
Eivind Stillingen
I am afraid it is how many of the younger generation now communicate by texting, with thumbs. No punctuation or grammar.
Cliff
an old f**t!
Shoot, think he just said it requires a sturdier driver stage, one with more quiescent current.
No idea why you guys are so hung up on the Siliconix 2N part, but here's one for the adventurous buyer: Salvats
Roughly $1 each.
(PS : hope you realise that the Idss range of the 2N556* goes all the way from 5mA up to 30)
No idea why you guys are so hung up on the Siliconix 2N part, but here's one for the adventurous buyer: Salvats
Roughly $1 each.
(PS : hope you realise that the Idss range of the 2N556* goes all the way from 5mA up to 30)
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Good choice! Alex has some small heatsinks there. Prepare you might need some, too.
Ok, offset is a bit strange but 60mV is not a too big problem imo. I thought it was up to 0.6V? Maybe measurements with Roar will shed some light on this. 😕
Good luck
Tommy
What do you mean by "check" R8, T3, T4 and T1.
R8 is a trimpot(check what?)
T3 and T4 are MPSA 42 not BC 546 B. Would BC 546B bee a better choice??
Bouth channels behave the same.
Eivind Stillingen.
What do you mean by "check" R8, T3, T4 and T1.
R8 is a trimpot(check what?)
T3 and T4 are MPSA 42 not BC 546 B. Would BC 546B bee a better choice??
Bouth channels behave the same.
Eivind Stillingen.
From experience sometimes the trimpots do not work properly even if they are new. By check I mean does the components work correctly, correct type/model, does the PCB layoute match the schematic in his area, in order to find the problem. My opinion is that BC546B should be used. Hope this helps.
