AB763 choke values

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bent765522
Posts: 12
Joined: Thu Nov 28, 2019 3:15 am

AB763 choke values

Post by bent765522 »

Hi all, one of my amps is a single channel AB763 build made by a reputable builder here in Nashville.. it’s more or less a single “normal” channel Vibroverb with a Bassman style OT. Sounds fantastic. The circuit appears to use vibroverb values throughout.

However the choke is something different.. it appears to be an old used choke, the marking on it appears to read
“A0-24159-0”

A google search suggests this might be a choke from an old Hammond organ, possible specs are:
14 HY
460 ohm

I’m not sure if this choke was chosen specifically, or it’s just what the builder had on hand.. as I mentioned the amp sounds great but I’m curious to hear what folks think of how this choke would compare to stock 4HY 90mA or 50ma Tremolux aa763 style chokes with regard to tone and feel. Thanks!
Roe
Posts: 1918
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Re: AB763 choke values

Post by Roe »

more resistance reduces screen current and voltage somewhat, giving a slightly softer attack. This is not a big issue with 6l6s, since they draw little screen current compared to el34s.

14hy gives a crisper, tighter bass, whereas 4hy sounds rawer and warmer normally
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Stevem
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Re: AB763 choke values

Post by Stevem »

If you don’t tell us how close to wide open you play your amp ( how close to power supply sag) then it’s impossible to relate to you what the sound and feel differences might be .
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