Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Cabinets-Speakers => Topic started by: TIMBO on July 01, 2014, 02:56:45 am

Title: Speaker?
Post by: TIMBO on July 01, 2014, 02:56:45 am
Hi guys, I pulled some speakers from a Peavey cab, and they are Eminence with the silver dust cap and square magnet. There was an odd one that is also an Eminence like this http://angela.com/fenderspeaker128ohmceramic.aspx (http://angela.com/fenderspeaker128ohmceramic.aspx) , but it measured 12ohms and the others measured 15 ohms????
 
Can this speaker used with an 8ohm output. Thanks
Title: Re: Speaker?
Post by: shortfuse on July 01, 2014, 07:13:52 am
Timbo
Sounds like a speaker with a voice coil going south.
Title: Re: Speaker?
Post by: HotBluePlates on July 01, 2014, 05:11:04 pm
... it measured 12ohms and the others measured 15 ohms????
 
Can this speaker used with an 8ohm output. Thanks

Let's answer the concrete question. Assuming the voice coil isn't going open, it's a 16Ω speaker.

You choose whether to use that on an 8Ω tap. Different people will argue vehemently for each side.
Title: Re: Speaker?
Post by: TIMBO on July 02, 2014, 01:41:49 am
Thanks guys, Cause it was a replacement for a square magnet speaker, I would have thought it would be the same impedance.The other three speakers measured 14.6 ohm.

I googled  fender/eminence replacement speaker and nothing turned up for 15 ohm, all were 8ohm??
Title: Re: Speaker?
Post by: HotBluePlates on July 02, 2014, 12:49:21 pm
See this thread (http://vintageamps.com/plexiboard/viewtopic.php?highlight=eminance&t=49716). If your speakers have the markings of the one in the pics (especially the "16" towards the end of the part number), it's a 16Ω speaker.

Cause it was a replacement for a square magnet speaker, I would have thought it would be the same impedance.The other three speakers measured 14.6 ohm.

The "marked impedance" for all of them is probably 16Ω. Or maybe 15Ω, but that seems more typical of British speakers.

I googled  fender/eminence replacement speaker and nothing turned up for 15 ohm, all were 8ohm??

Search "Eminence 16 ohm speaker" and plenty of results will appear.

D.C. resistance does not equal "speaker impedance". But d.c. resistance will always be less than speaker impedance, and usually a large %. So if it measures over 8Ω dcr, you might assume it's a 16Ω speaker (unless it's over 20Ω, then it's one of the uncommon 32Ω speakers). You will probably never see a speaker with a DCR under 8Ω that has an impedance of 15/16Ω, even though it's theoretically possible.
Title: Re: Speaker?
Post by: TIMBO on July 03, 2014, 01:45:24 am
Thanks Guys, Pic below has it as an Eminence and the size of the magnet I think it is a 100w, but I can't see any thing that says its a 15 or 16ohm. The cone has a number on it 451222-2 

I was wanting to use this speaker to replace the original speaker in the Leslie tremolo unit as the crappy 8" had a hole in the cone.

This is where it gets tricky....
The Fender Vibrotone and Leslie 16 &18 don't have an amp in then and would have to have an separate amp to power it. So I either build its own head, or power it from another amp, but if that amp already has say an 8ohm cab already connected could the leslie be connected to the 16ohm if it has one.

eg.

      --------------8ohm output---------------8ohm speaker cab
AMP
      --------------16ohm output--------------16ohm leslie speaker
   
                 

Title: Re: Speaker?
Post by: TIMBO on July 04, 2014, 01:25:56 am
Thanks Dr. The original speaker to my surprise was a cheap jap job. I would have thought that Leslie would have had a decent speaker but most of these units that have been converted to guitar use, this is the first thing that gets the flick.

This has some useful info http://www.nmia.com/~vrbass/vibratone/ (http://www.nmia.com/~vrbass/vibratone/) Thanks
Title: Re: Speaker?
Post by: Willabe on July 05, 2014, 12:01:16 pm
This has some useful info http://www.nmia.com/~vrbass/vibratone/ (http://www.nmia.com/~vrbass/vibratone/)

That's a Great site on guitar Leslie types!      :happy1:

Thanks soooooooo much for posting that Timbo.



                   Brad       :happy2:
Title: Re: Speaker?
Post by: TIMBO on July 07, 2014, 01:24:49 am
Thanks guys, I was wanting to use this speaker in the Leslie type cab and it looks like I may have to build a amp just for this cab. Thanks for your help.  :icon_biggrin: