Changing Speaker Impedance - Opinions?

Seeing and hearing is believing

Moderators: CurtissRobin, colossal, zaphod_phil, Daviedawg, Graydon

Post Reply
User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 1972
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Changing Speaker Impedance - Opinions?

Post by JMPGuitars »

I have a few 8 Ohm speakers I really like, but of course I'd rather have 16 Ohms for my 18 watt amps.

Obviously the easy answer is to sell/trade them for some 16 Ohm speakers. However, I'm curious about opinions on doing something like increasing the resistance with a high wattage wire wound resistor in series...

Other ideas? Opinions?
0 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

CurtissRobin
Senior Amp Tech
Senior Amp Tech
Posts: 1169
Joined: Sat 08/09/08 2:00 am
Location: Columbia River Gorge, Oregon Side

Re: Changing Speaker Impedance - Opinions?

Post by CurtissRobin »

A series resistor would give you a higher resistance but it'll change your sound substantially. Remember that a speaker voice coil is an RL (resistance-inductance) circuit and changing R without changing L changes the impedence-frequency curve, a.k.a. its response, to a given signal. Give it a try and let us know what you think.

KennyO
0 x

User avatar
JMPGuitars
Super Duper Admin
Super Duper Admin
Posts: 1972
Joined: Tue 09/18/12 8:00 pm
Location: South Central, MA
Contact:

Re: Changing Speaker Impedance - Opinions?

Post by JMPGuitars »

Which direction do you think the curve will go? Do you think it will be a tone curve shift, or with the response turn into mud?

I assume I need to use at least 20 watts for the resistor value? I'd just try it out for the heck of it if I have high enough wattage resistors lying around.
0 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale

CurtissRobin
Senior Amp Tech
Senior Amp Tech
Posts: 1169
Joined: Sat 08/09/08 2:00 am
Location: Columbia River Gorge, Oregon Side

Re: Changing Speaker Impedance - Opinions?

Post by CurtissRobin »

I'd expect some muddying of the sound. A resistor attenuates without regard to frequency while a coil in series attenuates highs ergo the combination will attenuate more at the high end than at the low end. Not much, but probably just enough to muddy the sound. OTOH if you've got one of the really bright 18 watt amps it could be the ticket to take the edge off. I've never tried it but it's come up in conversation every couple decades or so. It'll be interesting to see what you learn.

The resistor won't dissipate anywhere near the full power of the amp since the speaker still uses its share, but oversize resistors in this application is a good, conservative design idea.

KennyO
0 x

User avatar
Weldaar
Unrated
Posts: 6
Joined: Wed 07/12/17 6:11 pm
Location: NJ

Re: Changing Speaker Impedance - Opinions?

Post by Weldaar »

Two 8 ohm speakers will give you 16 ohms. I have two 8's in my cabinet and I run them at 16 ohms. You just have to wire them in series.
0 x

Post Reply