nuvistors
- Mike H
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#76
Silly question time ~ where in the circuit is this 295k? I'm looking at this ~ assuming it's still current:
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#77
PS: FWIW for 560k I would have automatically assumed something like 0.1uF, did in the above calculator, got the -3 dB @ 3 Hz; for 295k, 0.22uF for about the same effect
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- cressy
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#79
the 295k is where the 300k is in the above circuit, it needed amending due to the change from its original form. originally it was done for the 7f8w which required 300k but the nuvistor needed 295 instead. the 3.3uf was subbed in for the 0.22uf output cap.
the input on the amp is a 50k pot so i put 25k in to represent the pot half open and it came out at 20hz f3 point.
i put the biggest resistor i had (560k) between the signal pin and earth tag on the output socket, seemed like a good idea to stop the output impedance changing
the input on the amp is a 50k pot so i put 25k in to represent the pot half open and it came out at 20hz f3 point.
i put the biggest resistor i had (560k) between the signal pin and earth tag on the output socket, seemed like a good idea to stop the output impedance changing
- Mike H
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#80
Ah-hah thank you. That explains all yes.
If it helps my phono pre o/p is using 6.8uF ClarityCaps for the same reasons.
Yes you need a leak resistor of some sort across o/p socket otherwise if you turn it on before plugging it in, then plug it in the following amp gets a big SPIKE
If it helps my phono pre o/p is using 6.8uF ClarityCaps for the same reasons.
Yes you need a leak resistor of some sort across o/p socket otherwise if you turn it on before plugging it in, then plug it in the following amp gets a big SPIKE
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- cressy
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#81 Re: nuvistors
- cressy
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#82 Re: nuvistors
Quick question re re casing the phono stage, usual best practice when using an umbilical is to put the last psu cap in the circuit enclosure.
As this psu has one of nicks mj regulator boards on the end of the psu presumably the reg board should be in the circuit enclosure?
Or would it be better to have the last cap and the board in it
Cheers ant
As this psu has one of nicks mj regulator boards on the end of the psu presumably the reg board should be in the circuit enclosure?
Or would it be better to have the last cap and the board in it
Cheers ant
- Cressy Snr
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#83 Re: nuvistors
Merln Blencowe reckons a regulator should be as close as possible to the circuit it is regulating.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
#84 Re: nuvistors
Possible dumb question.
I am severely out of practice with anything to do with this.
Given that the heaters for the 2ds4 nuvistor is 2v, is there any reason why I couldn't use a 2v sealed lead acid battery to heat them?
I am severely out of practice with anything to do with this.
Given that the heaters for the 2ds4 nuvistor is 2v, is there any reason why I couldn't use a 2v sealed lead acid battery to heat them?
- jack
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#85 Re: nuvistors
I believe 2V nominal SLAs are actually 2.1V and float charge up to 2.25V.
Vivitur ingenio, caetera mortis erunt
- IslandPink
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#86 Re: nuvistors
Easy enough to knock that down with a resistor or two.
"Once you find out ... the Circumstances ; then you can go out"