Ohm meter readings?

[Allan S]

How come ohm meter readings are low(8ohms or lower) on displayed postings on ebay adds, for 16 ohm drivers and woofers claiming to have 16 ohm diaphragms? Thanks! :confused:

[Mr. Widget]

How come ohm meter readings are low(8ohms or lower) on displayed postings on ebay adds, for 16 ohm drivers and woofers claiming to have 16 ohm diaphragms? Thanks! :confused:It's simple really. An analog or digital volt/ohm meter measures DC resistance in ohms. A speaker's rating is typically it's AC impedance as opposed to it's DC resistance.

A speaker's voice coil has a DC resistance when the device is not playing a signal and an AC impedance when the device is playing a signal. To further complicate matters, the impedance changes with frequency. So a woofer that is rated as an 8 or 16 ohm woofer may be that impedance at a minimum point and several times that at other frequencies.


Widget

[Allan S]

It's simple really. An analog or digital volt/ohm meter measures DC resistance in ohms. A speaker's rating is typically it's AC impedance as opposed to it's DC resistance.

A speaker's voice coil has a DC resistance when the device is not playing a signal and an AC impedance when the device is playing a signal. To further complicate matters, the impedance changes with frequency. So a woofer that is rated as an 8 or 16 ohm woofer may be that impedance at a minimum point and several times that at other frequencies.


Widget
Thanks for the info it's very helpful! My woofers and drivers measure high 15's on the D.C. scale (16 ohm units) so is that more beneficial compared to the high 7's readings I see on those adds or is the main reason for showing the D.C. scale readings in the pictured adds is to prove the units are in working condition?

[Mr. Widget]

Thanks for the info it's very helpful! My woofers and drivers measure high 15's on the D.C. scale (16 ohm units) so is that more beneficial compared to the high 7's readings I see on those adds or is the main reason for showing the D.C. scale readings in the pictured adds is to prove the units are in working condition?If you are measuring high 15s for a 16 ohm JBL driver and you are using a DMM or VOM either you are doing something wrong, your meter is out of whack, or your drivers are not correct. A 6- 12 ohm DC reading is typical for a 16 ohm JBL.

If you are using an LCR meter, it may actually be measuring impedance at a given AC frequency. What drivers and what type of meter are you using?

The reason people do it on eBay is general ignorance typically, though it does show you that the VC isn't open.


Widget

[Allan S]

If you are measuring high 15s for a 16 ohm JBL driver and you are using a DMM or VOM either you are doing something wrong, your meter is out of whack, or your drivers are not correct. A 6- 12 ohm DC reading is typical for a 16 ohm JBL.

If you are using an LCR meter, it may actually be measuring impedance at a given AC frequency. What drivers and what type of meter are you using?

The reason people do it on eBay is general ignorance typically, though it does show you that the VC isn't open.


Widget
DMM, the 2461 drivers were within 6-12 range but the 2220B woofers still read 12.9 and 15.4 respectively after several tries. I have 3182 crossovers coming for the network, I would like to add 2405 slot tweeters to make it a 3-way set up,what crossover would you suggest 3105 or 3106? Keeping in mind that someday I'm considering switching out the 2461's for 2440's or 2441's. One final question if two 2220B woofers were to be used in each network do they connect to the two low frequency posts provided, with one woofer per post, on the 3182 crossover? Thank you very much for your time and patience!
Regards,
Allan

[speakerdave]

DMM, the 2461 drivers were within 6-12 range but the 2220B woofers still read 12.9 and 15.4 respectively after several tries. I have 3182 crossovers coming for the network, I would like to add 2405 slot tweeters to make it a 3-way set up,what crossover would you suggest 3105 or 3106? Keeping in mind that someday I'm considering switching out the 2461's for 2440's or 2441's. One final question if two 2220B woofers were to be used in each network do they connect to the two low frequency posts provided, with one woofer per post, on the 3182 crossover? Thank you very much for your time and patience!
Regards,
Allan

Your questions suggest there may be a deficiency in 8th grade physical science, i.e. What constitutes a circuit? I strongly urge you to do some reading on the level of Electricity Made Simple before you go any further and take the risk of blowing up something or frying an irreplaceable voice coil.

[Mr. Widget]

DMM, the 2461 drivers were within 6-12 range but the 2220B woofers still read 12.9 and 15.4 respectively after several tries.Well, the 2220B uses the 2220J kit which does have a very high published DCR spec. 13.2 ohms. Not sure why one would be as high as 15.4... possible corrosion in the leads or spring clips?

I'd go with the 3106 and build my own. They are simple. The circuit diagrams are found here (http://www.jblproservice.com/pdf/Network%20Schematics/3106%20Network.pdf).

Not sure about your driver upgrade path... you might do better to just swap them out. Also, mid horns will make a huge difference, pick them with care.


Widget

[Allan S]

Your questions suggest there may be a deficiency in 8th grade physical science, i.e. What constitutes a circuit? I strongly urge you to do some reading on the level of Electricity Made Simple before you go any further and take the risk of blowing up something or frying an irreplaceable voice coil.
I suggest living to the old adage "if you have nothing good to say do not say anything at all" and the world is full of too many assholes like yourself, try helping instead of criticizing!

[Allan S]

Well, the 2220B uses the 2220J kit which does have a very high published DCR spec. 13.2 ohms. Not sure why one would be as high as 15.4... possible corrosion in the leads or spring clips?

I'd go with the 3106 and build my own. They are simple. The circuit diagrams are found here (http://www.jblproservice.com/pdf/Network Schematics/3106 Network.pdf).

Not sure about your driver upgrade path... you might do better to just swap them out. Also, mid horns will make a huge difference, pick them with care.


Widget
Pick them with care? What to look for? Everybody raves about the 2482's but the frequency range of 6kHZ at the top does not allow for the 7000HZ or 8000HZ crossover point? Do they make the high frequency range sound great in a 2-way set up? By the way if you are ever in the Niagara Falls area (everybody comes to Niagara Falls once in their life,lol) drop me a line there's lots of great places to see, I can be your personal tour guide. Thanks have a great nite!

[speakerdave]

Second thought, if you want to connect a speaker to just one terminal I suppose you could listen to "The Sounds of Silence."

Or, with more help from Widget and others maybe you'll be able to make some speakers.

[Allan S]

Second thought, if you want to connect a speaker to just one terminal I suppose you could listen to "The Sounds of Silence."

Or, with more help from Widget and others maybe you'll be able to make some speakers.
Yes, that would be fantastic, have a great day!
Regards,
Allan

[Mr. Widget]

Pick them with care? What to look for? Everybody raves about the 2482's but...I wish I could I've you some simple answers. Here are some basic guidelines I'd suggest you try to follow.

1. Don't believe what "everybody" says on the Internet.
2. Don't assume what JBL published in the 50s, 60s, and 70s is gospel... they were still learning.
3. Unless you have a lot of time and money, don't invent. Copy.


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[Allan S]

I wish I could I've you some simple answers. Here are some basic guidelines I'd suggest you try to follow.

1. Don't believe what "everybody" says on the Internet.
2. Don't assume what JBL published in the 50s, 60s, and 70s is gospel... they were still learning.
3. Unless you have a lot of time and money, don't invent. copy.


Widget
Nothing to complicated, load a 4520 bin with two 2220b's one 2440 or 2441 and one 2405, using 3182 and 3105 or 3106 crossovers. Working on getting a pair of 4350's, I think they are pretty rough(not much money, $1500 or so, is that to much if everything is working?), will have a lot of question's on those considering my limited amateur knowledge. Thanks and have a great nite!
Regards,
Allan

[WDJ]

Aren't the 3105, 3106 and 3182 two-way crossovers?

[grumpy]

Conceptually, Allan stated it correctly. 3182 -and- 3105 or 3106.

[WDJ]

I've been wondering about "cascading" crossovers myself!

(Couple of 3105 units on the bay right now...)

[Allan S]

I wish I could I've you some simple answers. Here are some basic guidelines I'd suggest you try to follow.

1. Don't believe what "everybody" says on the Internet.
2. Don't assume what JBL published in the 50s, 60s, and 70s is gospel... they were still learning.
3. Unless you have a lot of time and money, don't invent. Copy.


Widget
Hi Widget, What do you think about a two 2220b(woofers) x800hz(3182) to 2482(driver mid.-low) x1200hz(3120) to 2461(driver mid.) x8000(3106) to 2405(driver high)? Thanks for your time!
Regards,
Allan

[Allan S]

Hi Widget, What do you think about a two 2220b(woofers) x800hz(3182) to 2482(driver mid.-low) x1200hz(3120) to 2461(driver mid.) x8000(3106) to 2405(driver high)? Thanks for your time!
Regards,
Allan

Hi again, or how about active crossovers with four small stereo amps? Or where do I go to buy after market crossovers for less money? Thanks again!
Regards,
Allan

[Allan S]

Hi again, or how about active crossovers with four small stereo amps? Or where do I go to buy after market crossovers for less money? Thanks again!
Regards,
Allan
Hi again Mr. Widget, I was reading one of your posts about ten years ago, you were considering making a custom pair of 3155 crossovers. Would you consider making more crossovers? Thanks for your time!

Regards,
Allan

.

[Mr. Widget]

Hi again Mr. Widget, I was reading one of your posts about ten years ago, you were considering making a custom pair of 3155 crossovers. Would you consider making more crossovers? Typically PMs are the best avenue for these direct one on one conversations, but because I do get similar requests from time to time I'll answer publicly here.

I'd love to help you out, but I no longer have the bandwidth to tackle these types of side projects. There are however numerous people on the forum who have the skills and perhaps one of them has the time to help.


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[Allan S]

Typically PMs are the best avenue for these direct one on one conversations, but because I do get similar requests from time to time I'll answer publicly here.

I'd love to help you out, but I no longer have the bandwidth to tackle these types of side projects. There are however numerous people on the forum who have the skills and perhaps one of them has the time to help.


Widget
Thank you very much for getting back to me, and have a great day!

Regards,
Allan