Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Banjan73 on March 30, 2026, 06:03:00 am
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Sheit.
I am struggling to understand how to connect my Hammond 1650H to a speaker selector switch. Attached is a picture of the datasheet. What kind of switch do I need here to make use of all the impedances (4, 8 and 16ohms)? And how the #&%! do I connect it? Some braniacs out there? Would be nice with a simple schematic.
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Look at the documents/files for this. https://www.amplifiedparts.com/products/impedance-selector-switch-rotary-hammond-1600-series#:~:text=Switch%20%2D%20Rotary%20Impedance%20Selector%2C%20for%20Hammond,1/4%22%20output%20jack%20and%20black%20chicken%20head
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You need this switch (https://www.amplifiedparts.com/products/impedance-selector-switch-rotary-hammond-1600-series) to have all three impedance selections available.
That switch looks mighty flimsy to me. I opted to be able to only have 4Ω and 8Ω available. Connect the Grn and Grn/Yel leads together and connect the Blk and Blk/Yel together. Use the Grn for 4Ω and use the Yel for 8Ω. Now you can use a robust SPDT switch to toggle between 8 and 8.
In the future you may want to buy the easy wire secondary version of the 1650 transformer. Same price but with straightforward secondary winding.
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Thanks to both of you.
Yeah, that secondary seemded ok when i glimpsed at it the first time.
But after scratching my head for a while, it gave up.
That switch seems nice, though. I will buy one of those.
P.S.
Why the €%# does Hammond provide this kind of secondary?
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Why the €%# does Hammond provide this kind of secondary?
You need to ask Hammond that question. There must be some advantage but I don't see it. Shortly after the 1650 OTs came on the market, Hammond introduced the easy wire 1650s. I suspect that easy wire version exists because of complaint about your issue.
The easy wire version for your OT is 1650HA. Look at this link (https://www.hammfg.com/electronics/transformers/classic/1608a-1650a) for more info on the easy wire secondary.
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Pff.
Shame I didn't know about that version before I ordered.
Anyway, think that "impossible"-wiring version is gonna work also..
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The MOD 101 uses the 1650P with a 4-8-16 selector switch. Take a look at that.
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Gee. Thanks for all info guys.
I have already ordered that switch. Who thought that such a simple selector switch would be that complicated...
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... Why the €%# does Hammond provide this kind of secondary?
It facilitates the best feasible coupling between primary amd secondary windings for all secondary connection options.
A hifi thing.
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Aha!
Thx for info!