Alnico Ohms ?

[rafe]

Hey All and happy post Thanksgiving. I sent off 2 Jensen alnico speakers to have reconed and they came back last week I put what I thought was the better of the two in my champ but quickly switched it to the second one because I thought the ceramic  jensen mod I had in it  previously was better sounding.....The second Jensen alnico sounds good in it ....I put the first alnico in my ray-meany magnatone and it's ok sounding .
So here is the question.....I asked for these speakers to be 4 ohms and when I checked the ohms on the
Jensen mod (ceramic) it read about 3.2 which seems normal .....the first alnico recone reads 1 ohm and I'm worried that it is not correct....I have not checked the second alnico in the vibro champ yet. I know I am measuring the resistance in the speaker and not the actual ohms of it , but is this out of kilter or is it acceptable ?

[bigsbybender]

Digital meters often give funny readings when dealing with low resistance... that said the 3.2 ohm (R) reading is about right on for the average 4 ohm speaker.  4 Ohms (Z) is about as low as any speaker coil will be wound to. I can't imagine any available 2 Ohm (Z) (1 Ohm R) coil that would end up in there by accident.
As far as coils reading differently between ALNICO and Ceramic.... a coil is a coil, they are constructed to fit in different designs of motor structure, but the reading should be in the same ballpark between speaker rating. Both types need the same amount of windings...

My DMM is always fooled by these low resistance readings (to the point of worthlessness) and it's a good model of a good brand... I went out and bought an analog meter just for the purpose of testing speakers. It wouldn't hurt to get a second opinion from another meter on that speaker.....
If it's reading any resistance at all and not reading "Open"... I say go for it and try it.  Impedance is measured at a nominal point. This point is not as crucial in the real world, as what is "reflected" between the speaker and Output transformer isn't constant under use. Yes some OT's are more sensitive than others if there is an "impedance mismatch" but as long as that speaker reads any resistance at all you should be in the clear for a Fendery 4 Ohm OT.


j.

[FYL]

the first alnico recone reads 1 ohm and I'm worried that it is not correct....I have not checked the second alnico in the vibro champ yet. I know I am measuring the resistance in the speaker and not the actual ohms of it , but is this out of kilter or is it acceptable ?

If your DMM is OK, the reconed speakers have a problem: a 4R speaker should measure app. 3R DC, not 1R.

[rafe]

Thanks FYL .....I checked with 2 different meters both analog one is tube and like I said the third 4ohm speaker a 8" ceramic mod Jensen reads in the proper range I'm going to check the other Alnico and post back ....
I'll probably have to call them monday ...They had a hard time getting parts on one of those speakers and that could be the reason it's not correct...
PS I just checked the other Alnico and it's 3.5 .....So now I've got to call and see what they are willing to do ........arrrrgh

[rafe]

Well just to post a follow up : I phoned the shop and they agreed something was wrong, he said he would talk to the tech and get back to me.He sent back an e-mail , The tech told him that unless it was something such as the leads touching the basket or each other to send it back under warranty. I never even thought to check that the lead must have shifted in transit, all is well. Both alnico speakers sound real good and I'm sure the will continue to get better. I will go ahead and recommend "Simply Speakers" a pleasure to deal with and I will use them again