K151 vs E155

[budney]

Can anyone tell me the technical differences between the 3 18inch instrument woofers?
I just recently picked up some of 4695 cabaret cabs. Seller said they were E155 woofers in them.

I ended up with a load of E155, 2 E151 and a single alnico K151! A few of the E155 and I think one E151 will need a recone. The E151 have aluminium dustcaps. One E155 has a ribbed cone so it seems to be a 2240? The K151 was reconed with a E155 kit by JBL some years ago, it sat in a box unused ever since. A shame I only have one as now I have to find another one!

From reading this forum I see some people mention that they are all slightly different woofers. The K151 and E151 seem to share the same basket, just with alnico and ferrite magnets being the difference. The E155 looks like the 2240/2245, and its spoken that they can be reconed as any of the 3.

I'm really looking for info on the K151 and E151. How exactly are they different to the E155? Are they underhung? I can't seem to find any technical info out there.

As for getting them reconed, there are aftermarket E155 kits out there that as far as I can tell use the same software as the JBL NLA kits, and a high quality edge wound voicecoil wound by Precision Econowind. It seems to be the same coil as the 2240/2245. Is the only difference between the 151 and 155 the coil?

Also it seems like all the drivers I have are 8 ohm, but JBL used to offer the K151 as 4 ohm? Still haven't figured out the benefit of 4 vs 8 apart from it using more power. I'm also trying to track down what the K151 was actually used for, most people say organs? I guess in the 70s when they were available there wasn't much that produced real sub frequencies apart from maybe a DBX boom box. I'm looking forward to getting another one so I can have a full alnico house party system!

[toddalin]

Also it seems like all the drivers I have are 8 ohm, but JBL used to offer the K151 as 4 ohm? Still haven't figured out the benefit of 4 vs 8 apart from it using more power.

Higher impedience will also have a higher BL. The BL is a measure of the "control" of the woofer movement with higher being tighter.

One benefit of 4 ohm is that SS amps will make more power into them. Another is that they can be seriesed to make 8 ohms and many companies use two drivers in their bass cabinets.

[Kay Pirinha]

Hi budney,

there's a table somewhere in this forum (each time I'm looking for it I don't manage to find it ) that lists any TSP of JBL transducers, including the ones you're focussing on. Perhaps it may help?

Best regards!

[RMC]

Cabaret Reference chart showing which model drivers were used in each box.

Richard

JBL Cabaret Series Reference Chart (1-1983)[1].pdf

[RMC]

Hi budney,

JBL E-151 had a very short life based on two JBL docs printed one after the other. K-151 was transferred to ferrite magnet as E-151 then shortly after replaced by E-155, no wonder there's little info about E-151, like a transition driver.

At the bottom of E Series doc dated 7/80 there's another doc dated 8/79 showing K-151 and E-151 with little info, but the doc above the latter (less than a year later) shows the E-155, no E-151 anymore... Pretty short career. I'll try to post for you some documents i have in as much as the site accepts their size, no guarantee.

There's at least another doc i have in my other lap top (haven't had time to transfer all i got to new laptop), in case i forget about that other doc just bug me here (i don't log in often) this way it will remind me to get it in the other computer for you, sorry somewhat busy these days...

Richard

JBL - E Series - E110, E120, E130, E140, E145, E151, E155 (1980).pdf

[RMC]

Have some other Cabaret and E series stuff but file size too large to post here. All info posted should answer your questions and keep you busy for a while. That's it for now. Regards,

Richard

[budney]

Hi Richard,

Thanks for the info posted, I had read these things in the past but hadnt had a chance to find them all in one place and compare. From reading these, it looks like the E155 was the upgraded driver, as the power handling has double from the 151. It's got different T/S parameters, Qts, VAS XMAX etc, but same flux, so all in all quite a different beast. Soon I will run them up and compare them. I'll take some measurements too and post on here for others to see.

It was the kit interchangeability that had me puzzled, as the K151 has been reconed with a 155 kit. So it got me concerned that perhaps the voice coil is not centred properly in the gap, or its wrong somehow in some other way to the K151 magnet and chassis. I can see that the K151 and E151 are the same just with different magnet construction and a slight increase in power handling. Also I've seen pictures of the E155 with an aluminium dustcap, but I'm struggling to understand why. I would have thought the Alu dustcap improves things in the midrange, as I would expect from the 15 and 12 inch drivers, E140, E120 etc. But I would never have thought to run an 18 inch driver so high. Is that what these 18s were designed for? To be able to run up into the midrange?

As far as application, I will be using all of these 18s in the 4695 cabaret cabs, with 4628b's on top. If I were to build a horn sub for a disco I wouldn't feel too happy about using the old K151 for that kind of duty anyway as I'd be worried about it surviving.

Thanks

[RMC]

This doc from Don Keele is a W horn article for K151, but at page 2 he mentions a box size and tuning for K151 so this may help you somewhat in case you don't build a more complicated W horn.

Richard

JBL K151 - W HORN Construction Notes and Specifications (1977).pdf

[RMC]

E Series tech sheet.

Richard

JBL E SERIES 110-8-e120-8-e130-8-e140-8-e145-8-e155-8_Tech sheet.pdf

[RMC]

Hi Budney,

RE "Also I've seen pictures of the E155 with an aluminium dustcap, but I'm struggling to understand why. I would have thought the Alu dustcap improves things in the midrange, as I would expect from the 15 and 12 inch drivers, E140, E120 etc. But I would never have thought to run an 18 inch driver so high. Is that what these 18s were designed for? To be able to run up into the midrange?"

All pics i've seen of E155 in 4695 boxes have Alu dustcap, this to extend response somewhat. Since it can also be used for bass guitar, not only sub use.

However, if you look at the Cabaret docs i posted you will see the 4695 frequency range covered is 30-2khz @ -10 db, not really high in the midrange in view of -10db spec, then actually more like low mid with a really usable frequency range, say 1khz or so...

Richard

[RMC]

K Series brochure re K151

Richard

jbl k_series.pdf

[RMC]

JBL Tech notes #3 and 3A regarding low frequency transducers, see pages 6 & 9 and page 4 respectively, for example

Richard

EDIT: Site won't accept size, could send it by e-mail to you, PM me with an e-mail address.

[Kay Pirinha]

I've meant this one: Thiele Parameters.pdf

I have it on my home PC's SSD, but couldn't find it online.

Best regards!

Edit: Oops, I see there's no E 151 mentioned in it??

[Robh3606]

Oops, I see there's no E 151 mentioned in it??

Just use the K

Rob

[Kay Pirinha]

Rob,

do you say that the K151 and E151 only differ in their magnet material and construction, but apart from this are the same speaker? This reminds me of the 2205H whose magnet JBL swapped from AlNiCo to ferrite during production.

Best regards!