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'60's 2x12" cabinet impedance? [message #23148]

Fri, 19 June 2015 12:50

redfarfisa
Messages: 4
Registered: August 2010

Junior Member

I have a beautiful white/silver Kustom 100 I got in the late '60's. I don't need to repair it, but I like using the cabinet (2 x 12" CTS) with my '68 Vibrolux Reverb. Does anyone know the impedance of these old Kustom cabinets? I don't want to blow anything up. I also like playing the Kustom head through other Fender speakers...

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Re: '60's 2x12" cabinet impedance? [message #23150 is a reply to message #23148]

Fri, 19 June 2015 14:12

chicagobill
Messages: 2006
Registered: April 2003

Senior Member

Hey, Combo Compacts rule!

Hopefully Pleat will have the official answer for you, but if you have an ohm meter, you can read the dc resistance of the cabinet and figure out what the impedance is.

Plug a cord into the cabinet and read the resistance from the tip to the sleeve. The reading that you get will be close to the impedance rating, but normally a little lower. So an 8 ohm cabinet would read about 6-7 ohms, a 4 ohm cabinet would read around 3 ohms, etc.

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Re: '60's 2x12" cabinet impedance? [message #23151 is a reply to message #23150]

Fri, 19 June 2015 15:05

pleat
Messages: 1454
Registered: June 2004
Location: Belding, Mi

Senior Member

If the original speakers are still in the 2x12 cabinet, each speaker will be 16 ohms wired in parallel for a 8 ohm total load for the cabinet.

You mentioned the cab is late 60's. If you bought it used back then, I'd remove the back panel to visually inspect the speakers, tighten any loose nuts and perhaps remove any objects that may have been passed through the port tubes.

If your running the Kustom K100 head on a fender cab. Fender used 8 ohm speakers in their 2x10, 2x12 and 2x15 cabs so you would have a 4 ohm total load. The Kustom K100-1 and K100-2 heads are 8 ohms.

pleat

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Re: '60's 2x12" cabinet impedance? [message #23152 is a reply to message #23150]

Fri, 19 June 2015 16:10

redfarfisa
Messages: 4
Registered: August 2010

Junior Member

Thanks for the info! I got the Kustom brand new like in 1969 (maybe 1970) - anyways, it's been very gently used (it wasn't really loud enough for what I was doing back then (RMI electric piano mostly), so I got a Kasino with 8 x 12" for the heavy work!) So, the 100 head will be fine with an 8 ohm speaker. Would using it with a 4 ohm cabinet damage anything? Also, would playing the Vibrolux (that expects a 4 ohm set of speakers) with the 8 ohm Kustom cabinet damage anything? What if I use the Vibrolux with its 4 ohm speakers plugged in the int speaker jack and the 8 ohm Kustom speakers plugged in the ext. speaker jack? What about a Fender Deluxe with its 8 ohm speaker and the 8 ohm Kustom speakers both plugged it? This would all be at very low volume. Thanks for your help! In the old days, we just plugged everything into everything else - I figure it's about time for me to learn about it!

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Re: '60's 2x12" cabinet impedance? [message #23153 is a reply to message #23148]

Fri, 19 June 2015 18:40

stevem
Messages: 4774
Registered: June 2004
Location: NY

Senior Member

If it's speakers are still the original CTS with square magnets, then they are Bass drivers and will sound a bit dull unless you click on the Fenders brite switch, and like Pleat posted the Cabinet will be wired for 8 ohms and plugging in a Fender tube amp that wants a 4 ohm load will knock 33 % of the Fenders wattage out from the impedance miss match!

Running a Kustom 100 head thru anything ( higher or lower) but a 8 ohm load will cut the amps 50 watts of RMS power in half!

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