switchable 2.5k/5k primary ot

drembo · 16th March 2004, 05:42 PM

I am building a single ended 300B amp using Hammond's 1627SE output transformer; 2.5k primary,4, 8 and 16 ohm secondary taps. I have read that many people prefer to use a 5k primary output transformer with the 300B tube that, while providing less power, gives a nicer sound. Would switching my 8 ohm speaker between tne 4 and 8 ohm secondary taps be equivlent to swiching between a 2.5k and 5k primary? That would be a nice switch to have on the back of my amp.

Fuling · 16th March 2004, 06:07 PM

Should work, I did it unintentionally when I prototyped my 6B4G amp.
You won´t even need a switch, just use separate terminals for 4 and 8 ohms.

16th March 2004, 05:42 PM	#1
drembo diyAudio Member Join Date: Aug 2003 Location: Orange, California	switchable 2.5k/5k primary ot I am building a single ended 300B amp using Hammond's 1627SE output transformer; 2.5k primary,4, 8 and 16 ohm secondary taps. I have read that many people prefer to use a 5k primary output transformer with the 300B tube that, while providing less power, gives a nicer sound. Would switching my 8 ohm speaker between tne 4 and 8 ohm secondary taps be equivlent to swiching between a 2.5k and 5k primary? That would be a nice switch to have on the back of my amp.

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16th March 2004, 06:07 PM	#2
Fuling diyAudio Member Join Date: Aug 2001 Location: Sweden (Mora)	Should work, I did it unintentionally when I prototyped my 6B4G amp. You won´t even need a switch, just use separate terminals for 4 and 8 ohms.