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I have an eye on LE14A woofers with new surrounds on auction sites, which are 16ohm, though.
Currently my C56 or L101 speakers are equipped with 8ohm LE14A.
Is it okay to use 16ohm LE14A instead of 8 ohm LE14A?
What are the benefits or drawback of 16 ohm woofers?
By the way, these speakers are 8ohm by factory default, and my McIntosh tube power amps are also hooked on to 8ohm input jacks.
Short answer is no. Long answer is that changing the impedance of the woofers would also change the passive crossover characteristics and thus require changing out the low pass filter components to agree with the new woofers. Theoretically halving the values of the choke and cap would do the trick but in reality it would require a lot of reiterative testing and swapping of components to return to the original frequency and slopes.
Quote:
Originally Posted by pyonc
If you do get convinced that you want to use 16 ohm Le14a(s) and believe you have found a pair to purchase >> make sure you that the seller first provides you with DCR measurements of the voice-coils before you send any money.
It's my position ( opinion ) that there never was such a thing as a 16 ohm Le14a ( apart from >> ignoring the foil-cal labelling ) they are just another example of JBL's legacy confusion in impedance labelling.
I've watched eBay for a couple of decades now and have never seen an LE14a ( no matter the labelling on the back ) that displays more than 8.0R on a multi-meter ( when the seller has bothered to take a measurement of the voice-coils ).
:)
Just looked at my JBL driver listing, identifying among other things nominal impedance for each of them, and i see no such thing as a LE14A having 16 ohm, only an 8 ohm version. Moreover, the factory DCR range spec for the latter is given at min. 5.9 ohm and max. 7.1 ohm. Again nothing suggesting an actual 16 ohm version would exist.
If you take a deep dive into the catalogs you will find that they were originally listed as 16 ohms 1960's. Just ask for a DCR reading as Earl suggested and it will tell you what's up. i would also ask for photo's of the drivers so you can see the foilcal and cones. Anything old enough to be 16 ohms is going to be Lansaloy cream to yellow original surrounds. Foam came in the late 70's.
Could be a re-coned set from the 60's done at a later date. Would probably be 8 ohms if this is true.
Best of luck and Happy New Year!
Rob :)
Getting a DCR reading (if an original cone) is a good idea, even better if it is posted here.
I'm with Earl K and RMC on this because:
1) I'm not aware of JBL ever offering a choice of 8 or 16 ohm LE14A woofers at a given time. It was a historical change.
2) The D123 likewise. The same question came up about the D123. Harvey Gerst responded that the D123 was originally labeled 16 ohm because it sounded better connected to the 16 ohm taps of the tube amps available at the time. When he posted that, I checked the DCR of four grey-frame 16 ohm D123's and two black-frame 8 ohm D123's. They were all within a small (less than 1 ohm) range of each other.
3) The 16 ohm tap would appear to offer the same advantages to the LE14A. Both drivers were so efficient any compromise of ultimate power transfer would rarely be an issue.
4) The D123 and the LE14A product lives both bridged the historical transition from tube amp market dominance to solid state. With the early solid state amps there was a new issue. Lower impedance loads would draw more current from the amp, good, but at some point would stress the power supply and circuit parameters and increase distortion numbers, bad. Also, users needed to know what was the lowest impedance the amp could safely drive without danger of thermal runaway that would cause a lot of smoke and excitement and destroy the amp. Power rating with specified distortion level was usually given for an 8 ohm load. When both 8 and 16 ohm power ratings were given for a solid state amp, the 16 ohm numbers were smaller. A 16 ohm speaker would therefore appear to deny the amp owner his watts. If the voice coils would actually be safe for an amp rated to handle an 8 ohm load, there was no harm in changing the label. Again, ultimate power transfer would rarely be an issue.
Thanks a lot for your kind replies.
Here is the link to the Ebay listings on this:
https://www.ebay.com/itm/144346589822
https://www.ebay.com/itm/284420302686
The pictures show they are 16ohm LE14A on the foilcals.
I've asked the seller for the DCR reading on this.
By the way, this is the specifications of LE14A, according to the JBL catalogue from the 1960s:
LE14A:
Impedance 16 ohms
Power capacity 30 watts
Free air cone resonance 25cps
The seller just informed me that its DCR read 5.8 and 6.1, respectively.Quote:
Originally Posted by Earl K
Thanks for your reply.Quote:
Originally Posted by Robh3606
It's 5.8 and 6.1, according to the seller.
It's 5.8 and 6.1, so it's similar to 8hm LE14A, right?Quote:
Originally Posted by RMC
If you can establish that JBL only made one version of the LE14A that's all you need to know. The actual impedance may well be in between what would generally be listed as 8 or 16 ohms. All thats important from your perspective is does the impedance of the drivers match that expected by the passive crossover.
Thanks for your comment. Actually that bothers me.Quote:
Originally Posted by Riley Casey
My C56 or L101 is a 8-ohm speaker, with LX10 network and 1.5khz crossover, so I'm thinking twice about buying this 16 ohm woofer.
By the way, I hear JBL called LE14A a 16ohm at first in the 1960s, but later called it 8 ohm. Not sure if this is true.
Alright, thanks for your thoughtful feedback.Quote:
Originally Posted by speakerdave
Quote:
It's 5.8 and 6.1, so it's similar to 8hm LE14A, right?
In my book, yes