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bldozier
02-20-2017, 02:05 AM
Hi,

can someone one provide a chart comparing the 3
mentioned 8" drivers. I'am looking for one more
2108, which I may or may not find.
Iam looking for a temporary substitute for
the missing driver for now.

I understand that the aquplasless 2115 may
play higher then the le8t without the cone
coating the chart dictates a significant
dropoff of the le8t @ around 500khz while the 2108 is
steady. Maybe a mass ring can be added to
extended the range down low of the 2115.
Does the le8t use a mass ring?
76086

bldozier
02-20-2017, 02:19 AM
Does the grap provided too much of a disparaging
curve for the tandem to be used together
temporarily?

Can an someone provide a graph of the
112 an 2108

Flodstroem
02-20-2017, 08:58 AM
Hi, Does the le8t use a mass ring?

No, only Aquaplas ;)

bldozier
02-20-2017, 10:47 AM
Ok thank you flodstroem... I thought not
but read somewheres they do...
so how would I go about creating a comparison
chart for all 4 drivers.

Flodstroem
02-20-2017, 12:38 PM
An alternative could be to purchase a temporary substitute for the 2108 like this model (and it looks to be cheap) if it still has the full SPL and frequency response ;)
Later you could always sell them or keep them for another speaker project :D
http://www.ebay.com/itm/JBL-2118H-8-8-ohm-Midrange-Speaker-Pair-Tested-DCRs-4-9-4-9-Clean-2614-/252761452549?hash=item3ad9c1b005:g:yQwAAOSw2xRYm2F-

bldozier
02-20-2017, 05:13 PM
I've decided against using 2118s. Just looking for
a comparison of the above mentioned
drivers

bldozier
02-22-2017, 04:46 AM
Anyone

Earl K
02-23-2017, 08:29 AM
I've decided against using 2118s. Just looking for
a comparison of the above mentioned
drivers
Anyone (?)

Brian,

You should take Flodstroems advice and buy a pair of good used 2118h(s) as standins while you wait to obtain another 2108 .

The 2118 is a good speaker, which is why it was used as the basis for the 108H ( > used in the much loved 250ti series of speakers ) .

( As requested & fwiw ), here's a comparison made of the 2115 vs the le8t vs the 2108 ( using your Japanese source for my basic trace info ) .
- From the traces seen, the 2115 doesn't look very usable in my opinion ( > when using a standard 4315 network ).
- Now, that's only "if this Japanese trace can be believed" ( which is in some doubt ).

FYI, relative levels for the 3 are not correct because the Japanese originator of the files referenced all his captures to a single 1K point ( instead of referencing to a constant voltage ).
- As an example, I would expect that the 2115 should be more efficient than the le8T in the mid-band area above 200hz ( but here it's not ).


What I've shown is only relevant to get an idea of the various response curves ( but not absolute levels ) & even these 3 responses are quite suspect since I notice his graphs all have a common midband suck-out ( 400-900 hz ) for one reason or another ( I suppose it's a measuring anomaly ) .

76119

:)

PS: my vertical scale is purposefully somewhat "Hi-Rez" ( so as to hi-light the differences ) .

Earl K
02-23-2017, 08:41 AM
The software used to capture these traces ( which happens one at a time ) is called FPGraphTracer (http://labs.fprawn.com/index.php/fpgraphtracer/) ( available for Windows & Mac ).

Each graph was then saved as a .frd file .

Each frd file was then imported into REW (http://www.roomeqwizard.com/beta.html) for display and posting purposes ( REW is available for both Windows & Mac ) .

I find this ray tracer works best on color traces ( in fact, I've never successfully captured a trace that was similar in color to the grid pattern ).
- OTOH, used on a color trace, it's very good and dead simple to use.

:)

Flodstroem
02-23-2017, 01:07 PM
The software used to capture these traces ( which happens one at a time ) is called FPGraphTracer (http://labs.fprawn.com/index.php/fpgraphtracer/) ( available for Windows & Mac ).

Each graph was then saved as a .frd file .

Each frd file was then imported into REW (http://www.roomeqwizard.com/beta.html) for display and posting purposes ( REW is available for both Windows & Mac ) .

I find this ray tracer works best on color traces ( in fact, I've never successfully captured a trace that was similar in color to the grid pattern ).
- OTOH, used on a color trace, it's very good and dead simple to use.

:)

Thanks Earl for the interesting hints and info. ;)

bldozier
02-23-2017, 02:05 PM
Yea thank you. Mr. K.

bldozier
02-23-2017, 02:12 PM
Brian,

You should take Flodstroems advice and buy a pair of good used 2118h(s) as standins while you wait to obtain another 2108 .

The 2118 is a good speaker, which is why it was used as the basis for the 108H ( > used in the much loved 250ti series of speakers ) .

( As requested & fwiw ), here's a comparison made of the 2115 vs the le8t vs the 2108 ( using your Japanese source for my basic trace info ) .
- From the traces seen, the 2115 doesn't look very usable in my opinion ( > when using a standard 4315 network ).
- Now, that's only "if this Japanese trace can be believed" ( which is in some doubt ).

FYI, relative levels for the 3 are not correct because the Japanese originator of the files referenced all his captures to a single 1K point ( instead of referencing to a constant voltage ).
- As an example, I would expect that the 2115 should be more efficient than the le8T in the mid-band area above 200hz ( but here it's not ).


What I've shown is only relevant to get an idea of the various response curves ( but not absolute levels ) & even these 3 responses are quite suspect since I notice his graphs all have a common midband suck-out ( 400-900 hz ) for one reason or another ( I suppose it's a measuring anomaly ) .

76119

:)

PS: my vertical scale is purposefully somewhat "Hi-Rez" ( so as to hi-light the differences ) .

I wonder if the demagnization of the alnico
motor affects response of the le8t above the mentioned
200hz. Maybe a ferrite motor maybe best used as a companion
speaker to the 2108 or bi amping

Earl K
02-23-2017, 03:33 PM
I wonder if the demagnization of the alnico
motor affects response of the le8t above the mentioned
200hz. Maybe a ferrite motor maybe best used as a companion
speaker to the 2108 or bi amping

Alnico demagging will manifest itself in at least 2 visible ways ( when viewing the FR ).

One; the bass can bloom a bit ( maybe by a couple of db ) due to less magnetic control ( damping ) on the cone/coil assembly from the magnet.

Two; the mid to high-mid comes down a couple of db.

200hz?? I can't really tell you off-hand what the Fs tipping-point is ( think in terms of the fulcrum of a teeter-tooter having a frequency ) .

The trace of the le8t I displayed looks like it might be the result of a bit of demagging > ( it has LF bloom & some loss of midrange linearity ).

OTOH, the thing is, that trace comes from the blog of a very fastidious speaker repair-man ( a real craftsman ) that seems to check every repair for linearity, ( sometimes gauss levels in the gap ) as well as a check for distortion products // so that all suggests I might be wrong in my own ( seat-of-the-pants ) assessment .

:)

bldozier
02-23-2017, 03:40 PM
It is a 2" am 3" arrangement, being compared.
Maybe one day you mr k can add the 2118 an 112
into that fray... the 2118 being 2" vc as well.

Flodstroem
02-23-2017, 04:31 PM
If looking at the Bl product the compared speaker are far from each other LE8T/2115 has only a Bl of 6.2/6.8 compared to the 112A (Bl=12) and the 2108 (Bl = 13)
The 2118H looks more to be equal to the 112A though it has a Bl of 11. Thats why I recommended the 2118 but also because of the fair price of a decent pair :)

mech986
02-24-2017, 01:22 AM
If anyone needs magnets re-magged, Speaker Repair Pros in Garden Grove (the successor to the late Orange County Speaker Repair) has their remagnetizer and can do the job. They may be one of the last 3 in the US (maybe outside of JBL themselves) who have remagnitizer units.

bldozier
02-24-2017, 03:04 AM
Any idea of the other 3. Talked with a few indys
whom do it maybe they outsourced

mech986
02-24-2017, 03:39 AM
Great Plains Audio does it, primarily for Altecs, but they probably could do any speaker for the right price. Check with them to see.

bldozier
02-25-2017, 03:44 PM
Yes they do.
Anyone else come to mind.

mech986
02-25-2017, 04:09 PM
I thought there was a major JBL servicing center in New Jersey (?) maybe that might have done it, don't remember their name though. However, shipping is probably only 20-30% more to anywhere mid-country compared to east coast.

FE3T
03-04-2017, 06:32 PM
If looking at the Bl product the compared speaker are far from each other LE8T/2115 has only a Bl of 6.2/6.8 compared to the 112A (Bl=12) and the 2108 (Bl = 13)
The 2118H looks more to be equal to the 112A though it has a Bl of 11. Thats why I recommended the 2118 but also because of the fair price of a decent pair :)

Managed the following specs by installing a 116H-2 aftermarket kit into a 2118 basket.
Xmax should be +/- 4,5mm.

Tubejunkie on the bay have a pair of 2118 baskets for 13.45$ and Speakerexchange wants 44$ for a kit.

And just I case you wonder, 2118 and LE8T does fit in the same hole, and have the same bolt pattern, probably also the 2108.