jbl 2256 and jbl w15gti dc voice coil resistance vs. operating impedance

[original jblguy]

both woofers have 2x6 ohm dc v.c. resistance, but the 2256 is rated at 2x8 ohms each voice coil
so could i assume since both drivers are very similar that the w15gti would present an 8 ohm load on my amp per coil?
:)

[Lee in Montreal]

Will JBL sell me a pair of 2256 over the counter if I want to repair my Line Areas? Just curious.

[Dr.db]

both woofers have 2x6 ohm dc v.c. resistance, but the 2256 is rated at 2x8 ohms each voice coil
so could i assume since both drivers are very similar that the w15gti would present an 8 ohm load on my amp per coil?
:)


Any idea.... :confused:


I`d like to use two W15GTi´s with a homehifi-amp(2-channel), but most of them are just 4ohm stable.
So connecting the two coils of a W15GTi in parallel, would result in 3ohms for each amp-channel. I´m afraid I will kill my amp doing that kind of setup :(

[Mr. Widget]

Any idea.... :confused:


I`d like to use two W15GTi´s with a homehifi-amp(2-channel), but most of them are just 4ohm stable.
So connecting the two coils of a W15GTi in parallel, would result in 3ohms for each amp-channel. I´m afraid I will kill my amp doing that kind of setup :(Wire them in series-parallel and you'll be safe. Wire each woofer's pair of coils in parallel as you were planning and then the two woofers in series.


Widget

[Ruediger]

and 3 Ohms DC resistance corresponds to 4 Ohms "average impedance", so everything is okay.

Connect the two voice coils of each speaker in parallel, and connect each such speaker to its own amplifier channel.

I did not get the point of connecting things in series. If one did, each speaker would see the other speaker's DC resistance in series with the amplifier's output impedance (plus resistance in cables and in crossover), and this would mess up the speakers Qt. Qt determines what you can do with a speaker cabinet-wise. High Qt speakers are only good for boom-boxes.

Ruediger

[Dr.db]

Wire them in series-parallel and you'll be safe. Wire each woofer's pair of coils in parallel as you were planning and then the two woofers in series.

Widget

This would be great for a one-channel amp, but I´m dealing with a stereo-amp ;)




and 3 Ohms DC resistance corresponds to 4 Ohms "average impedance", so everything is okay.

Connect the two voice coils of each speaker in parallel, and connect each such speaker to its own amplifier channel.



Connecting two 4ohm coils in parallel would result in a 2ohm load, that sounds pretty scary for the amp :blink:



I just found this JBL-manual;
http://de.jbl.com/tl_files/catalog//jbl/canada/owner_manual/W15GTi%20Mkll/GTi_W15_MkII_OM_EN.pdf

It claims 3ohms or 12ohms "average impedance".... So each coil is 6ohms. Not very practicle...

[Lee in Montreal]

This would be great for a one-channel amp, but I´m dealing with a stereo-amp ;)

Considering that the W15GTI will most likely going to be used under 50/60Hz, you can run them in mono. They are for subs anyway, not main speakers.

[Dr.db]

Connecting both woofers together results in 6ohm total... I`ve got a 2-channel amp which is 4ohm stable... Bridged 8ohms.... I don`t get the sense in connecting both woofers together, please explain.

[Lee in Montreal]

The W15GTi is NOT a domestic woofer to be used with domestic amplifiers. It was designed for an automotive environment where amps are stable down to 2 Ohms, and it is the norm. It was metionned in a previous post that you don,t want to connect each voice coil in series as it will alter Qt. So, to get some impedance compatible with a domestic amp, then you shall use two woofers, connected in serie, and used in mono. Or four woofers (two per side). Or find a domestic amp that is stable down to 2 Ohms. :D

The Peavey 4000 is stable down to 2 Ohms

http://peavey.com/products/index.cfm/item/702/112584/CS%26reg%3B4000

[pos]

AFAIK the W15GTI and the 2256G are exactly the same woofers (only the dustcap and color is different).
As already stated by Ruediger, the W15GTI *is* a dual 8 ohms VC woofer (Re = 6 ohms per VC, similar to a 2235H...).
I don't know how they came up with that "6 ohms" marking, but this is pure non sense.

[Ruediger]

AFAIK the W15GTI and the 2256G are exactly the same woofers (only the dustcap and color is different).
As already stated by Ruediger, the W15GTI *is* a dual 8 ohms VC woofer (Re = 6 ohms per VC, similar to a 2235H...).
I don't know how they came up with that "6 ohms" marking, but this is pure non sense.

For each bass driver
connect the two voice coils in parallel
connect the bass driver to its dedicated amplifier output.

The bass drivers will have a resulting average impedance of ca. 4 Ohms - which is fine - and a DC resistance of ca. 3 Ohms -which is fine as well.

Ruediger

[Dr.db]

I have to apologise!!

I did not read the manual correctly ;) It says 3ohms DC, but not for each coil... It`s measured with both coils in parallel.
So you guys have been right all the time, sorry.
This looks like the W15gti really is a 2*8ohm driver :) Which makes it a stable 4ohms speaker (coils in parallel) for a homehifi-amp.

http://www.manualslib.com/manual/284739/Jbl-W15gti.html