PSTX choke mod

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Will
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#1 PSTX choke mod

Post by Will »

This is a choke accross the secondaries of a power tx + & - Ime not saying much because it is dependant on the circuit I believe but its a keeper for me.
Simply it is a power choke accross the + and - of the power transformer before the rectification. The supply I used was a bridge into a EZ80 1uf maplin choke 220uf maplin choke 220uf the supply to my phono amp.
So if you have a supply close to this I would be interested to hear the results and a scope would tell whats going on.
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Nick
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#2

Post by Nick »

Interesting observation, I wonder just whats going on. I don't have a power supply to try this on just now, as they all have regulators after them at the moment, which might mask any change. I will try it on the new amps power supply when thats built, and see if anything obvious is top be seen on a scope. But I am not sure I would see anything, normally the sorts of changes we talk about hearing don't show up with the crude test gear I have at my disposal.
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Nick
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#3

Post by Nick »

Was it a center tapped TX?

Just wondering if there would be some reduction in the offset created by unequal voltages from the two half's of the secondary.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Will
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#4

Post by Will »

Nick
Its a 240v Maplin tx, I put a Maplin choke in and it buzzed but a Hamond was o.k. I tried it on the driver supply with the 5842 shunt and it sounded thin. This came from the AA, they were also plugging power chokes into the mains supply.
Ive been listening for 2 weeks so its not just a sound change.
The sound is holographic, mid to die for and smooth peaks, I blamed the cartridge for rough peaks sorry 103.
Will
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#5

Post by Will »

Found the thread on AA in (tweaks/DIY) section search "ac choke"
Andrew
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#6

Post by Andrew »

Hi Will,

Are they doing this between Live and Neutral? Or have I misunderstod?

Seems they parallel up the chokes as well???? :?

Need to read this more.

cheers,

-- Andrew
Will
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#7

Post by Will »

Yes live-neutral and earth to choke frame. Hammond 193Q or M pricey though.
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Nick
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#8

Post by Nick »

Ahh, now that would possibly be working by shunting any DC away from the transformer.
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#9

Post by Andrew »

Bit of a waste surely? Those choke's are going to draw something like hundred mA, at least!

cheers,

-- Andrew
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Nick
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#10

Post by Nick »

But only 30ma or so in the states, 60hz 115v

Can't help thinking there are cheapers ways though.

But Will, wasn't your discovery on the secondary?
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Will
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#11

Post by Will »

Nick, yes there was a post and someone thought the Hammond .5H choke in the photo on the Lamm site could be across the secondary.
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Nick
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#12

Post by Nick »

Possible I guess, I have looked at that, its too small a value to be choke input, so I have assumed that the supply is CLC then the regulator. At leat thats what I am using. I guess the real one will be very different to what I have, but its just a bit of fun, and I have been wanting to try the valve since hearing Andrew I's amp.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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