JBL-E120 - 4?

JBL-E120 - 4?

Postby Pete B. » Thu Jan 01, 2009 1:09 pm

Ouch!
I just recieved 2 brand new JBL-E120's.
They are E120-4's... 4-ohm.
I thought they were going to be 8-ohm ('never thought to check).
I can send them back for full refund, (or swap for 8 ohm speakers if he has them) but what a PITA.
I was going to run them in parallel... 'Guess I can run them in series.
WWJD?
Thoughts?
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Re: JBL-E120 - 4?

Postby Chuckles » Thu Jan 01, 2009 3:18 pm

Sure - wire them in series.
Seems like I've been here before...

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Re: JBL-E120 - 4?

Postby tigerstrat » Thu Jan 01, 2009 4:46 pm

So instead of the expected parallel -8's for a total of 4ohm, you will have series -4's for a total of 8ohm.
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Re: JBL-E120 - 4?

Postby Pete B. » Thu Jan 01, 2009 6:22 pm

Yeah, I guess that's the deal.
I have power amps that can run 4ohm or 8 ohm loads (not sure about 2ohm load... have to check the manual).
Now what was the reason for running speakers in series vs. parallel again?
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Re: JBL-E120 - 4?

Postby Chuckles » Thu Jan 01, 2009 6:34 pm

The only reason to wire series vs parallel afaik is to change the impedance of the cab.
Seems like I've been here before...

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Re: JBL-E120 - 4?

Postby jonarobb » Thu Jan 01, 2009 6:39 pm

Parallel is generally preferred if you're looking to achieve the full rated power output of the amplifier. If output isn't your big concern then either series or parallel is cool granted your load is correct. The age old rule of thumb is: Parallel= Smoother Response, Series=More stress on the amp and tone.

Speakers wired in series have more incidents of flyback voltages into the output transformer. If you're using an older Fender this ain't such a hot idea.

Hope this helps!
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Re: JBL-E120 - 4?

Postby tigerstrat » Thu Jan 01, 2009 9:05 pm

jonarobb wrote:Parallel is generally preferred if you're looking to achieve the full rated power output of the amplifier. If output isn't your big concern then either series or parallel is cool granted your load is correct. The age old rule of thumb is: Parallel= Smoother Response, Series=More stress on the amp and tone.

Speakers wired in series have more incidents of flyback voltages into the output transformer. If you're using an older Fender this ain't such a hot idea.


Never had it explained that well before, in terms of application. Nice! So... how about say a 2x10 cab, w/ 4ohm drivers wired in series (4+4=8) for an 8ohm cab... and there are TWO such cabs, wired parallel (8/2=4) with each other, showing a total of 4ohm to the amp? iow what's that considered afa the rules of thumb, and any similar electrical drawbacks?
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Re: JBL-E120 - 4?

Postby jonarobb » Thu Jan 01, 2009 10:40 pm

tigerstrat wrote:
jonarobb wrote:Parallel is generally preferred if you're looking to achieve the full rated power output of the amplifier. If output isn't your big concern then either series or parallel is cool granted your load is correct. The age old rule of thumb is: Parallel= Smoother Response, Series=More stress on the amp and tone.

Speakers wired in series have more incidents of flyback voltages into the output transformer. If you're using an older Fender this ain't such a hot idea.


Never had it explained that well before, in terms of application. Nice! So... how about say a 2x10 cab, w/ 4ohm drivers wired in series (4+4=8) for an 8ohm cab... and there are TWO such cabs, wired parallel (8/2=4) with each other, showing a total of 4ohm to the amp? iow what's that considered afa the rules of thumb, and any similar electrical drawbacks?


The balanced parallel wiring of the 2 8 Ohm loads will satisfy the OT in that case. It's a bit of trickery. The output transformer wants to work efficiently to achieve full power. Again, it's all relative to what you're trying to achieve in relation to the full rated output of the power section. The rule of thumb is not a hard fast rule. But does come in handy if you're thinking in terms of fidelity. Series wiring in general right off of the OT taps is considered low fi. It doesn't mean that it's wrong or anything.

A power section rated at 100 watts at 4 Ohms will work harder to achieve it with a series load than it would with a parallel load. The sacrifice is in the bandwidth. They might both sound as loud as a 100 watt amp should, but the amp wired with a series load directly off of the taps will sound slightly strangled.
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Re: JBL-E120 - 4?

Postby Pete B. » Fri Jan 02, 2009 12:25 am

I was also looking at this info:
(The speaks I received look like the E120's seen at this site.)
http://www.dozin.com/cabs/speaker.html

I'll have to think about this...
With regard to the E120's in general... maybe two 1x12 cabs would be better for me (no roadie!).
Also, both of my SS power amps actully run at "full power" with 4 ohm loads.

Or just load 'em both into one 2x12 cab, and have two speaker cords (one per speaker) coming directly from each speaker.
I could still run either mono or stereo (stereo means I could preserve the "clean" tone through on speaker, and "effects" through the other).
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Re: JBL-E120 - 4?

Postby Chuckles » Fri Jan 02, 2009 4:22 am

That's an interesting concept. How would you go about splitting the signal into the two stereo paths?

I too have two SS amps, and the most powerful (headroom out the wazoo!) option is to run either bridged into 8 ohms. This means that of the two E120-8s I recently bought, I'll only go through one and I will build two 1x12 cabs for them. The second E120 will serve two purposes: first, as a replacement if I blow the first; second, my backup should whichever SS power amp I bring to a gig craps out will be to plug tubes into the power section of the Twin Reverb head I'm currently using as a pre-amp... then, I'll need both speaks in parallel to give the TR the 4 ohm load it's looking for. This seems to be a problem with my choices of power amps (an '80s Peavey DECA 700 and a SoundTech PS802) that risk damage if they see a bridged 4 ohm load, but so it goes. At any rate, I'm gassed that even one E120 sounds very, very good by itself - particularly with the PS802, which delivers 800w of crystal-clean power (over the top, but as I said... headroom galore!).

Both amps can obvioulsy use their the full power capacity to a stereo setup at 4ohms, but I guess I'm a bit confused as to the speaks they will be feeding. They'd need to be independent for each channel, ie: either 1x4 ohm or 2x8 ohm per channel (parallel), yes?
Seems like I've been here before...

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Re: JBL-E120 - 4?

Postby playingdead » Fri Jan 02, 2009 5:57 am

Pete B. wrote:With regard to the E120's in general... maybe two 1x12 cabs would be better for me (no roadie!).
Also, both of my SS power amps actully run at "full power" with 4 ohm loads.

Or just load 'em both into one 2x12 cab, and have two speaker cords (one per speaker) coming directly from each speaker.
I could still run either mono or stereo (stereo means I could preserve the "clean" tone through on speaker, and "effects" through the other).


Two 1X12 cabs with E-120s is a lot easier to handle if you don't have a roadie or at least a road case ... ask me how I know ;-)

I recently A-B'd my 2X12 HT cabinet against my homemade 1X12 cabinets stacked, all with E-120s, sonically, the difference was negligible (all three are open-back cabs).

People do "WDW" rigs -- "wet, dry, wet" rigs -- when they are going for tone like The Edge gets with U2 -- they put the delays in the stereo cabs and a straight guitar signal through the center. That wouldn't be particularly effective with things like overdrive or envelope filter, though, where you don't really want the clean signal mixed in, although there are ways around that if you're using something like a GCX and don't mind a wiring octopus back there.
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Re: JBL-E120 - 4?

Postby Pete B. » Fri Jan 02, 2009 10:38 am

Chuckles wrote:That's an interesting concept. How would you go about splitting the signal into the two stereo paths?


I typically use a volume pedal that has one input and two outputs, and then run to an Alembic F2B (Input A is the Mutron III path, Input B is the MuTron Octave Divider path). I have been running Stereo rigs for Pedal Steel for years, and I have found separating these effects gives me a better sound than running them in series (I'm still hoping to find some pictoral evidence of how Jer had his Mu and Octave Divider wired... Did he use the Aux out to the Mu3???... I have found that this makes a huge difference, imho).
Multiple effects in parallel (via patch bay) (and in stereo) sound better to me and allows for greater control of each, compared to multiple effects in series, but that is based on my own experiments.
Last edited by Pete B. on Fri Jan 02, 2009 11:44 am, edited 1 time in total.
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Re: JBL-E120 - 4?

Postby playingdead » Fri Jan 02, 2009 10:51 am

How do you get it into the house mix, Pete?
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Re: JBL-E120 - 4?

Postby Pete B. » Fri Jan 02, 2009 11:44 am

Mic 'em both, pan 'em straight up.
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Re: JBL-E120 - 4?

Postby Pete B. » Mon Jan 05, 2009 1:15 pm

O.K. here's the update...
I'm sending these speakers back.
I finally had a chance to give them a full inspection (up till now I only opened the box, saw they were 4-ohm, and said WTF?... didn't even pull them out of the box (didn't have time to install/test or anything due to the random distribution of reality, in general).
Although they were supposed to be brand new, both of them have clearly been mounted before because they have holes in the cork gasket where the 4 secondary mounting holes are (there a 4 primary holes that go through both the frame and the gasket... to use the other 4 holes in the frame you would have to puncture the cork gasket).
Secondly... when I pushed lightly on the cone of the first one, it was frozen... when I pushed a little harder it moved but was noisy and sticky... the other one moved in and out freely with no noise or rub.
The guy apologized and said my refund would be mailed today. He said that he had a total of 6 (all JBL E120-4's) that were sealed, and he just grabbed/shipped two without checking them before shipping.
I trust this guy as I have been doing biz with him over 10 years on mostly Pedal Steel stuff.
Life goes on!... and, well...
You know it's gonna get Stranger!...
:shock:

Actually, I might keep the one that works... "one in the hand" as they say!
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