Choke values

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gtomax
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Choke values

Post by gtomax »

General advice I've seen on chokes is "any standard choke is fine" - why is that?

What is the sonic or playing feel difference between a 3.5H and 4H choke? What about a 100ma vs. 150ma rating?

Surely there must be some difference?

I'm restoring a 5E8-A that has some unknown aftermarket choke and my choices to replace it are the Heyboer HTS-5099/HY022699 (4H, 90ma, 105 ohms) or the Mojo 777 (3.5H, 100ma, 100 ohms).
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pompeiisneaks
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Re: Choke values

Post by pompeiisneaks »

As far as I understand it, the choke has no major impact on tone, not having one can. RC based filtering is great, but when you can do LC the ability for the inductor to forcibly slow/stop sag, is great. The power supply is helped by this before it gets to the actual power tubes, so the impact is only on 'how much power can I consistently deliver' to the tubes themselves. Therefore, more choke is less sag, or you can just do more RC filtering. Either way, it's part of the trade offs. (That and SS rect vs tube). If you want and like sag, use tube rectification and don't use any LC filtering and you'll be likely to have a bit more. Under deliver with a lower than expected power supply, like Leo did with the early amps, and you add to that. If you don't what that sag at all, do SS rect and either a good LC/RC filter setup, or very high RC filtering. I've noted that's one of things Dumble seemed to do, up the filtering significantly. Look at the Tweedle Dee Deluxe, he went from 20uF on all filter nodes to 33uF. Similarly on the ODS etc, quite a lot more filtering to get consistent power.

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Re: Choke values

Post by pdf64 »

http://schems.com/schematicheaven.net/m ... _schem.pdf
Neither of those chokes can accommodate the required current, need 200mA minimum, and one that won't drop too much HT, so under 50 ohms.
Perhaps aim for 2H inductance. See what fits in the chassis space available http://www.hammondmfg.com/153.htm

If a choke saturates eg due to excessive current flow, its inductance will collapse, so pointless having it there.
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Re: Choke values

Post by pompeiisneaks »

Oh yeah I did skip that part, you definitely would melt the choke if it wasn't rated for the current capacity of your amp. That's a must :)

Thanks pdf64

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Re: Choke values

Post by tubeswell »

gtomax wrote: Wed Aug 16, 2017 5:29 pm I'm restoring a 5E8-A that has some unknown aftermarket choke and my choices to replace it are the Heyboer HTS-5099/HY022699 (4H, 90ma, 105 ohms) or the Mojo 777 (3.5H, 100ma, 100 ohms).
Those chokes will burn in a 5E8A because the choke sees the DC current supply for the whole amp, including the 6L6 plates. You want a choke rated for at least 120% of the maximum current draw. The average current draw is about ~150mA in that amp, so I'd use a minimum 180mA rated choke, or 200mA even better.
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Re: Choke values

Post by Roe »

yes, weber sells a 5-8h 200ma choke for the 5e8a - it seems to be 125 ohms if I remember correctly
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Re: Choke values

Post by Stevem »

A choke does not effect tone, but it will sure will effect play feel dependant if all of the amps D.C. Output goes thru it , or if just from the output tubes screen on up the line in feed thru it!
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gtomax
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Re: Choke values

Post by gtomax »

Thanks all!

Roe it looks like that's a 125ma choke: https://www.tedweber.com/hy014684 is that the one you're thinking of?
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Re: Choke values

Post by gtomax »

Got in touch with Heyboer and getting one made to spec. Gracias everyone
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