Choke Position?

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Cressy Snr
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#16 Re: Choke Position?

Post by Cressy Snr »

The semi-omnis, which is why I'm mentioning it.
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andrew Ivimey
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#17 Re: Choke Position?

Post by andrew Ivimey »

What if you just left the choke out altogether? Imho it would not sound so good but why not try as it would be so simple to do?

Many eons ago in a far off galaxy I knocked up a pp 2x 6dn7 per channel amp that I thought was top notch -I'd included a choke (CLC) in the psu and for some reason thought 'Take our the choke!' It was a sweet sounding little amp before and afterwards..., it was a sweet sounding amplifier too. I did not investigate but could have and really should have...might do so again as it was a balanced pp m as well. A version of that amp went to a Witham do.
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#18 Re: Choke Position?

Post by Cressy Snr »

andrew Ivimey wrote: Sun Dec 31, 2017 5:19 pm What if you just left the choke out altogether? Imho it would not sound so good but why not try as it would be so simple to do?
Thanks for that Andrew,
I could remove the choke of course, but then I'd have 500V of HT off the lowest secondary tap (375V) on my mains TX. I can't see even a mighty 2A3-40 taking kindly to that. Choke input is mandatory with the transformer I have unless I start regulating with a 6336A.

Oops! Gone right back to the start of this thread.
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#19 Re: Choke Position?

Post by andrew Ivimey »

As we do! Oh well, happy new year and confusion to all politicians. We can take this up again next year...
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pre65
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#20 Re: Choke Position?

Post by pre65 »

Cressy Snr wrote: Sun Dec 31, 2017 2:34 pm The semi-omnis, which is why I'm mentioning it.
Thanks for posting about this.

I've got one of the GK-71 monoblocks on the operating table at the moment. I've drawn out the way it is now, and then drawn out the way it will be with the chokes wired up differently.Then I have a reference when I come to do the other monoblock.

Might actually move some wires tomorrow, Jan 1st 2018. :)
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pre65
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#21 Re: Choke Position?

Post by pre65 »

Just thinking.

As I use two chokes on each GK-71, both 10H but different makes, would it be worth trying 1 in the positive line (as choke input) and 1 in the negative line ?
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#22 Re: Choke Position?

Post by Cressy Snr »

Personally Phil,
I would go the whole hog straight away and put them both in the 0V line as they have done here:
Image

The earth point needs to be put EXACTLY where Turner has shown it.
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pre65
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#23 Re: Choke Position?

Post by pre65 »

Thanks Steve, I decided to follow Fig 3 about an hour ago. :)

I've updated my GK-71 thread.
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#24 Re: Choke Position?

Post by Mike H »

I'm a bit late, but I've done this, put the input choke on the negative or "earth side", of the rectifier; there's no difference compared to putting it on the positive output side, the circuit works exactly the same. (The electrons are not bothered which way round.) My reason for doing it was because I've got two chassis, PSU on one, & amp on the other, and I want to keep the choke on the PSU chassis & not move it to the amp chassis. It's choke input so the only way that can work is if the choke is put into the negative output side of the bridge rectifier. The bridge rectfier negative half is two silicon diodes in the PSU chassis, and the positive half is a GZ37 on the amp chassis. The supply capacitors are in the amp chassis. Hope that makes sense.
 
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#25 Re: Choke Position?

Post by pre65 »

What does the resistor/cap across L1 in Fig 3 do ?

http://www.turneraudio.com.au/audiofilt ... page2.html


Does it lift ground ? :?
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#26 Re: Choke Position?

Post by Cressy Snr »

Looks like it's supposed to be a spike/resonance damper
I left it out because:
a. I didn't have the right parts, because....
b. The DCR of my choke is not the same as theirs.

No ill effects from leaving it out in my case.
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#27 Re: Choke Position?

Post by Mike H »

Well the capacitor makes it a tuned circuit, which raises its reactance at a particular frequency. The effect is like increasing the inductance of the choke, if you get the values right.

Yes I've done this as well. :D IIRC I use 0.22uF with 1 or 2 Henries, can't remember exactly.

I think the resistor should damp the tuned circuit, so less of a peak at the resonant frequency. I haven't tried this though.


HTH
 
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