Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Cabinets-Speakers => Topic started by: Diverted on September 05, 2018, 02:18:02 pm

Title: impedance mismatch: I know, i know it's been asked a million times. But ... ?
Post by: Diverted on September 05, 2018, 02:18:02 pm

Trying to wrap my head around the millions of different opinions I've seen on this in the past few days. I've never been steered wrong here so at the risk of annoying people with this same old question, I am wondering:

I have a speaker that specs out on my digital multimeter at about 5.1-5.2 ohms.
I have a Fender Champ clone with a single 8 ohm tap; the output transformer's a new Classic Tone.

Looking for trouble? Or am I good?

Thanks and I apologize in advance for the question :laugh:

Title: Re: impedance mismatch: I know, i know it's been asked a million times. But ... ?
Post by: SILVERGUN on September 05, 2018, 02:30:14 pm

You're 100% OK

You're measuring the resistance of the voice coil and most speakers will read similarly.

Impedance is frequency dependant and not equivalent to a static resistance reading.

Title: Re: impedance mismatch: I know, i know it's been asked a million times. But ... ?
Post by: Diverted on September 05, 2018, 02:41:34 pm

Thanks Silvergun. My main worry is running the amp too hot with this mismatch, as the 6V6 is probably going to be driven pretty hard in this amp. I wish I had an output trnasformer with 4/8 taps, but if I'm good with this speaker into an 8 ohm tap I'm happy.

Title: Re: impedance mismatch: I know, i know it's been asked a million times. But ... ?
Post by: SILVERGUN on September 05, 2018, 02:49:30 pm

Quote from: Diverted on September 05, 2018, 02:41:34 pm

Thanks Silvergun. My main worry is running the amp too hot with this mismatch, as the 6V6 is probably going to be driven pretty hard in this amp. I wish I had an output trnasformer with 4/8 taps, but if I'm good with this speaker into an 8 ohm tap I'm happy.

Nothing to worry about...
That speaker is probably "rated" at 8 ohms (even though the resistance of the coil is 5.2 ohms)

Here's a decent simple explanation:

From this article: https://www.lifewire.com/speaker-impedance-3134705

Title: Re: impedance mismatch: I know, i know it's been asked a million times. But ... ?
Post by: Diverted on September 05, 2018, 04:04:29 pm

Ok, that’s clear to me. Thanks for the help on this 👍