JBL E120 Help...

JBL E120 Help...

Postby thetumblerspdx » Fri Feb 10, 2012 2:16 pm

Hey,

Looking to get some E120s for my 75 Twin and there's one that popped up here on Craigslist in Portland. However, I know nothing about speakers and can't identify if the cone is in good shape here or what. Any thoughts on this? It looks like it's in great shape but.....

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Re: JBL E120 Help...

Postby myoung6923 » Fri Feb 10, 2012 3:47 pm

It kinda looks like there is a small tear in the cone. And I don't know what seems to have spilled arond the dust cap...

I would be wary
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Re: JBL E120 Help...

Postby TRG » Fri Feb 10, 2012 4:45 pm

I was thinking the same thing about that tear near the dust cap and the mystery seepage coming out of the dust cap. I'd pass...just my $.02
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Re: JBL E120 Help...

Postby thetumblerspdx » Fri Feb 10, 2012 7:41 pm

Great, thanks folks. I'll keep me eye out for some more here locally.
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Re: JBL E120 Help...

Postby playingdead » Sun Feb 12, 2012 6:05 am

One important thing to do when you're looking at one before buying is to gently push the cone in and out, and listen for any rubbing sounds. If it's rubbing, it's the voice coil and it's toast. If it doesn't move in and out easily, or if it sticks, the magnet's been jarred out of alignment, and it's also toast. They are so expensive to recone you want to be very careful.
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Re: JBL E120 Help...

Postby barefootdave » Sun Apr 01, 2012 4:45 am

I am leaning toward a pair of E120s on the bay (after missing a pair of K120s last weekend by about 4 minutes on a buy-it-now)

They are 16 ohm; is there any reason not to get those? There is a pair of 8 ohm available also, but I would prefer to be a little on the lower volume side, and my understanding is that 16 ohm would be a bit quieter with the 50w head I am using. The head has a switch to go 4/8/16 ohm.
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Re: JBL E120 Help...

Postby hippieguy1954 » Sun Apr 01, 2012 5:04 am

Ohms do not affect volume, if that is what you are asking.
You can wire two 8 ohm speakers for 16 ohms (series) or 4 ohms (parallel).
You can wire two16 ohm speakers for 32 ohms (series) or 8 ohms (parallel).
Personally, I like the 8 ohm speakers because they are a little more versatile.
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Re: JBL E120 Help...

Postby eric » Sun Apr 01, 2012 6:16 am

Good point.. I believe that only In tube amp power sections, a mismatch in impedance, will affect volume and headroom, but in solid state amps, ohms WILL affect the output .. Is that correct Hippie?
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Re: JBL E120 Help...

Postby hippieguy1954 » Sun Apr 01, 2012 7:35 am

eric wrote:Good point.. I believe that only In tube amp power sections, a mismatch in impedance, will affect volume and headroom, but in solid state amps, ohms WILL affect the output .. Is that correct Hippie?


Well, that is two different things.
Mismatched impedance between speaker and amp is not good for any amp. Especially going below the amp specs for ohms. Above is usually fine because it is less draw on the amp.

As far as output, the lower the ohms of the speaker/speakers the higher the output watts of the amp. The higher the watts, the more volume if wanted/needed, but it will not affect the volume at lower volume settings on the amp. It will still be the volume you set it on. It only allows for higher volume setting before distorting.

There is a debatable school of thought (which I feel is true) that more watts even at lower volume allows for better sound reproduction.
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Re: JBL E120 Help...

Postby strumminsix » Sun Apr 01, 2012 7:55 am

I'm not sure what is debatable. Per http://en.wikipedia.org/wiki/Ohm%27s_law

I = V/R
where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms. More specifically, Ohm's law states that the R in this relation is constant, independent of the current.
...

That can also be extrapolated to use Watts or Power. But always the same - the resistance lowers. Mathematically, ceteris parebis that going from a 8ohm to a 16 ohm will cause your output to decrease by half.
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Re: JBL E120 Help...

Postby hippieguy1954 » Sun Apr 01, 2012 10:11 am

strumminsix wrote:I'm not sure what is debatable. Per http://en.wikipedia.org/wiki/Ohm%27s_law

I = V/R
where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms. More specifically, Ohm's law states that the R in this relation is constant, independent of the current.
...

That can also be extrapolated to use Watts or Power. But always the same - the resistance lowers. Mathematically, ceteris parebis that going from a 8ohm to a 16 ohm will cause your output to decrease by half.


This is all true, strumminsix! However, if you wire your speakers for 8 or 16 ohms, you still have a volume pot on the amp to compensate. You can make it loud or not.

One reason to wire or use speakers at higher ohms is to not harm the amp. As you know, many amps cannot handle 2 or 4 ohm loads. Some can. It depends on the brand.

The only other reason would be to protect the speakers if they are rated at lower watts.

The debatable thing (which has nothing to do with the above) is about ears. Not science at all.
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Re: JBL E120 Help...

Postby eric » Sun Apr 01, 2012 11:30 am

My original question was a bit vague I suppose. I was trying to clarify some stuff I was reading on TGP.. And I've read through a ton of the subject on here, but...

1. A 40 watt amp with an 8ohm power rating+an 8ohm speaker is exactly as loud as a 40 watt amp with a 4 ohm rating and 4 ohm speaker?

2. The mismatch in a TUBE amp's recommended rating+ speaker, will always result in less output.
The same mismatch in a SS power amp will always result in more output no matter the direction?
But in a solid state amp , that can safely run @ 4,8,16, changing between different speakers with a 4,8,16 ohm rating with say a single 1x12, will produce different outputs, respectively.
How is this? Does anybody see what I'm asking?
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Re: JBL E120 Help...

Postby hippieguy1954 » Sun Apr 01, 2012 11:47 am

eric wrote:My original question was a bit vague I suppose. I was trying to clarify some stuff I was reading on TGP.. And I've read through a ton of the subject on here, but...

1. A 40 watt amp with an 8ohm power rating+an 8ohm speaker is exactly as loud as a 40 watt amp with a 4 ohm rating and 4 ohm speaker? YES

2. The mismatch in a TUBE amp's recommended rating+ speaker, will always result in less output. NO. lower ohms than the amps spec will result in higher watts and higher ohms will result in lower watts
The same mismatch in a SS power amp will always result in more output no matter the direction? NO. It works the same with tube or SS amps.
But in a solid state amp , that can safely run @ 4,8,16, changing between different speakers with a 4,8,16 ohm rating with say a single 1x12, will produce different outputs, respectively. YES
How is this? Does anybody see what I'm asking?


I'm pretty sure I know what you are asking.
The bold print (above) are your answers. If you are still uncertain, PM me. :smile: :smile: :smile:
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Re: JBL E120 Help...

Postby eric » Sun Apr 01, 2012 11:51 am

Thanks for the clarification! That's it hippie...buncha wankers over there on TGP!!!
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Re: JBL E120 Help...

Postby JonnyBoy » Sun Apr 01, 2012 12:00 pm

does anyone know what kind of glue to use to repair the dustcaps? the place said crazy glue, but I dont want a flooding issue like above.
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