Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jojokeo on June 04, 2013, 09:35:40 pm

Title: rotary impedance switch rating
Post by: jojokeo on June 04, 2013, 09:35:40 pm

Looking for minimum ratings required of a rotary impedance swich for the OT's secondary please??? (say for using 4, 8, & 16 taps for up to 50 watts max)

Title: Re: rotary impedance switch rating
Post by: PRR on June 06, 2013, 10:06:32 pm

28V 3.6A.... IF you hot-switch.

You can probably use a 1A switch if you only switch while silent/off.

Title: Re: rotary impedance switch rating
Post by: jojokeo on June 07, 2013, 12:12:18 am

Thanks PRR it's about what I figured. I wouldn't "hot switch" an impedance change like I would going between different speakers or cabs. I saw these on the bay and thought they should work for the majority of amps (<50Watts) http://www.ebay.com/itm/Centralab-Rotary-Switch-1461-Lot-Of-5-New-In-Box-1-Pol-3-Pos-1-5-amp-/321136251271?_trksid=p2047675.l2557&ssPageName=STRK%3AMEWAX%3AIT&nma=true&si=uExlVS515fz%252F1MxvxNa9JdCqF1M%253D&orig_cvip=true&rt=nc (http://www.ebay.com/itm/Centralab-Rotary-Switch-1461-Lot-Of-5-New-In-Box-1-Pol-3-Pos-1-5-amp-/321136251271?_trksid=p2047675.l2557&ssPageName=STRK%3AMEWAX%3AIT&nma=true&si=uExlVS515fz%252F1MxvxNa9JdCqF1M%253D&orig_cvip=true&rt=nc)

Title: Re: rotary impedance switch rating
Post by: woolly on June 07, 2013, 01:25:56 am

I use Doug's 3 way switch. rated 6amp.

Title: Re: rotary impedance switch rating
Post by: kagliostro on June 07, 2013, 10:29:08 am

Some time ago I put a similar question asking about a formula to know which is the current flowing in the OT / Speaker Path

PRR give me the necessary info as to establish the current flowing in the Speaker Cable

Unfortunately that isn't one thing that entered definitively on my brain and I'm not able to find the info in the forum and the copy I saved on my PC

K

Title: Re: rotary impedance switch rating
Post by: jojokeo on June 07, 2013, 11:12:35 am

We figure out the OT's primary specs all the time (over & over) but rarely are people ever concerned with the secondary specs except how the impedance affects the primary's reflection on the power tubes. We even discuss conjunctive filtering & zoebel networks but nothing breaking down the voltage & current hitting the speaker(s).