There is not a load for the output capacitor on the schematic.
I will be driving a TDV using the 51. Without a load resistor there will be two capacitors in series.
I suspect we are expected to know this needs to be added. I looked for a post concerning this and did not see one.
I am placing the stage within the amplifier. Maybe it is common knowledge to place this resistor at the connector but I will not be needing a connector.
Hope this isn't too dumb.
Thanks,
I will be driving a TDV using the 51. Without a load resistor there will be two capacitors in series.
I suspect we are expected to know this needs to be added. I looked for a post concerning this and did not see one.
I am placing the stage within the amplifier. Maybe it is common knowledge to place this resistor at the connector but I will not be needing a connector.
Hope this isn't too dumb.
Thanks,
Not a dumb question at all. It will probably raise the high pass filter frequency by several Hertzs. If you are using the amp for higher frequencies only, it would not be an issue.
I suppose most amplifiers have a high value resistor to ground at their input. I have to admit that I have an amp that I built that has an input capacitor but does not have a resistor to ground at its input. With the DIY FE, the high pass frequency probably increases from about 2Hz to 7Hz. I could place an 100k resistor to ground either at the FE output or amplifier input if I was concerned.
I suppose most amplifiers have a high value resistor to ground at their input. I have to admit that I have an amp that I built that has an input capacitor but does not have a resistor to ground at its input. With the DIY FE, the high pass frequency probably increases from about 2Hz to 7Hz. I could place an 100k resistor to ground either at the FE output or amplifier input if I was concerned.
I'm not an EE either.... but every circuit that I worked on, had a grounding resistor at the input... hmm... I suppose, come to think about it, the input impedance is between the + and - input signals.. not between - and GND. So all you lose is the input reference to its own ground, not seen by the source driving it.
Eons ago, when I was designing metrology circuits, we used balanced lines with a 100Kohm between + and - and a 1Mohm to ground... you are right, as I recall the input impedance was then 100Kohm...
One last question then.. does not having that grounding resistor affect noise? Why didn't you include it?
Eons ago, when I was designing metrology circuits, we used balanced lines with a 100Kohm between + and - and a 1Mohm to ground... you are right, as I recall the input impedance was then 100Kohm...
One last question then.. does not having that grounding resistor affect noise? Why didn't you include it?
It's not that there were no resistors to ground anywhere, it's just no resistor in front of the capacitor.
As far as why not, well, it goes back to not being an EE. My amplifier was a variation of an existing circuit.
There are amplifier circuits that do not show a grounding resistor at their input. So It is a matter of recognizing and understanding its implications.
But I am constantly learning, and there is a lot more to learn.
As far as why not, well, it goes back to not being an EE. My amplifier was a variation of an existing circuit.
There are amplifier circuits that do not show a grounding resistor at their input. So It is a matter of recognizing and understanding its implications.
But I am constantly learning, and there is a lot more to learn.
Not to barge in on a cool conversation, but this was something I was specifically looking at the other night. It may be of interest.
https://www.diyaudio.com/community/threads/ba2-crippled-f4.208593/
Edited to add - I can't seem to get it to go to one post with the link. I didn't mean for you guys to go to the full thread... even though it's a short one. See posts #5 and #6 for a slightly similar discussion.
https://www.diyaudio.com/community/threads/ba2-crippled-f4.208593/
Edited to add - I can't seem to get it to go to one post with the link. I didn't mean for you guys to go to the full thread... even though it's a short one. See posts #5 and #6 for a slightly similar discussion.
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I think what I wrote was slightly misunderstood.
The TDV 51 has an input capacitor and the required load resistor afterwards - I do not think it would work without that.
I was concerned the two caps in series would do what they do.
The amps in question are crossed over at 100 Hz so I am not concerned with the high pass frequency at the lower limit- I worried that it might sound funny.
Always worrying about nonsense - wondered if the load resistor at the output of the FE2022 might change the value of the load resistor of the amp - I guess it would lower it (if it affects it at all) and this would not be a problem using the recommended 100K.
Thanks for the input.
The TDV 51 has an input capacitor and the required load resistor afterwards - I do not think it would work without that.
I was concerned the two caps in series would do what they do.
The amps in question are crossed over at 100 Hz so I am not concerned with the high pass frequency at the lower limit- I worried that it might sound funny.
Always worrying about nonsense - wondered if the load resistor at the output of the FE2022 might change the value of the load resistor of the amp - I guess it would lower it (if it affects it at all) and this would not be a problem using the recommended 100K.
Thanks for the input.
Where can I find this power supply project?Hot off the bench, regulated bipolar supply dialed in and ready to power a pair of FE2022 preamp boards.
Thanks for sharing this project @Ben Mah!
@Gerrit Kroesen : Yes, I think so. As far as I can tell, the 2sk209 is pretty much the 2sk117 in SMD form.
And the 2sk117 has the same pin out as the 2sk170 (not surprising since they're both Toshiba parts.)
And the 2sk117 has the same pin out as the 2sk170 (not surprising since they're both Toshiba parts.)
In your case with no sig gen or a scope safer to keep it there.
If worried too much about distortion try 10 - 22 pF instead, and sleep sound knowing you've done the minimum.
Don't understand the urge to get rid of it.
Is it because caps have bad name in general?
Or because it's difficult to find one in your neck of woods?
Old organs - Yamaha, Kawai, Farfisa, are good sources of styrene caps in that range.
If worried too much about distortion try 10 - 22 pF instead, and sleep sound knowing you've done the minimum.
Don't understand the urge to get rid of it.
Is it because caps have bad name in general?
Or because it's difficult to find one in your neck of woods?
Old organs - Yamaha, Kawai, Farfisa, are good sources of styrene caps in that range.
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