need help choosing a JBl 128H replace driver

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#22
Yes it seems with the monacors etc. bass would be compromised, at least according to the online calculator I used. The peerless would have little midbass hump even sealed, but maybe it wouldn't sound too bad. The upside is it's affordable and it seems generally pretty well liked, buying & selling should be easy. Could be worth a shot. There's switches for -2dB for both mids and highs in the 120ti so that provides some adjustment and I could always fine tune the resistors. I suppose it has l-pads.
 
#23
Just a little update, though I'm not the OP of this thread... I decided to go with Dayton Audio DC300-8 - very affordable and according to simulations they should be reasonably close to the originals. 1dB less sensitivity though, but I think I can live with that and there's -2dB switches for mids and highs - depending how they sound, I could easily modify the attenuation to finetune balance.

According to my sims with the Daytons there's going to be a +2dB (relative, in gain plot not in SPL) bass hump peaking at about 60-70Hz, then falling down to F3 of about 40Hz (128H about 45Hz) - I think I can live with that and sealing the port the response looks quite nice too, starting to slope down from 100Hz with -3dB point being at 50Hz. If the driver performs like that in real life, I should be able to get satisfactory bass response out of it. In their graphs Dayton Audio show the midrange from around 300Hz to 900Hz a bit recessed with the worst dip centering around 700Hz - that is a bit concerning (XO is at 800Hz) but we'll see how it sounds in real life.

I'm in a lucky situation I haven't heard the speakers with original woofers 🙂 Absolutely anything will be an upgrade over the "drivers" they came to me with - cheap 4 ohm car audio subwoofers with no usable response anywhere near 1k and horrible 100Hz one note bass... The sad thing is the previous owner has also enlargened the cutout hole for the woofers to make the shitty car speakers fit... according to my measurements I should be still good for the Daytons but fitting them well might be a little trickier than it would be with the original cutout.

The woofers should be with me within a week. If the Daytons don't sound any good in the 120ti I can always figure out a speaker project to use them in 🙂 I suppose they are a bit out of their league in speakers of that caliber, but better than nothing for sure...
 
#24
Boyan Silyavski said:
As a follow up i found the original 128H drives. Very nice change, deeper bass and surprisingly better mids and highs. Well worth the money. BUt even reconed one of them had a rubbing problem that i had to fix. So like sb said " buying old drives is like buying empty baskets, whatever they tell you"
Click to expand...


The 128H sounds better than any other woofer you might find, the natural sound of the L-112 is the almost perfect integration of the woofer and the LE-5 midrange, surprisingly the aluminum coat on the phenolic diaphragm of the tweeter attenuates a bit the response at 12 khz.
Some time ago a friend has a pair of L-112 and his tweeters almost lost the aluminum coat so the tweeter almost was brown as is phenolic and the high frequencies sounded more crispy and extended, I personally like it more with the worn aluminum coat, most people think that excellent tweeter is aluminum but is not, is phenolic with a coat of aluminum.
I f I find a pair of L-112 I will buy them and remove the tweeter diaphragm and wash it with thinner in order to remove the aluminum coat, I don't care if it looks uglier and sound with more air, more extended highs.
 
#25
Boyan Silyavski said:
Hi guys,

need some help with 12 drivers please.

Some background:

I have a pair of JBL L112 from many years. When i obtained them they were not with the original 12" 128H drivers, but some other 22xx something and as they were rotten i send them to the garbage bin. It happened that at same time i had some new like vintage 12", no name, so i just dropped them in. They play surprisingly well, even feeded by 150W 8Ohm amp full power, not that i do that very often nowadays .
Meanwhile some other nice speakers passed here but at the end the JBL 112 stayed, i guess i find them perfect for me, sound, size, WAF
Now they are carefully placed in room and sound very nice.



So why to change the 12" then?

Mainly because i would like some more bass, which i am sure i am missing with these.
Then the 128H are not new, expensive to ship to Europe, very hard to find and who knows how they are reconed or repaired.
Apart from that i would like to learn DIy speaker design, at least a bit, cause i looked last 2 weeks at DIY speakers and honestly couldn't choose one to build. Due to high price of speakers >1000euro, or low power, or this or that.. Incredible. i looked at least at 200 designs. The speaker i would like to build would be like the Statements but 2x10" instead of 2x 8" or even better 1x or 2x 12" bass in a transmission line cabinet. This SUMMONER 1293SRTL is one i like, but they are in Australia, i am in Europe... If there was a kit combining the Statements with the Summoner ...

In other words i realise i am absolutely ignorant and will need a lot of time and first completing some projects before i make my dream speaker.

So its obvious i could at least play with what i have. plus just finished my 8x4 cnc so i am eager to "better" things around me.

The idea though is to start from things i love, i know and have idea what i want.

So my plan is some step by step side projects for fun, while learning, reading, learning to measure, etc:
-find suitable 12" driver for the JBL
-make a clone of the L112 and now that i have figured the bass driver, see how the other could be exchanged with better modern ones
-make a clone of the L150, which is essentially L112 in higher enclosure +
-make some other speakers, for example Statements, Sb240 or Vota 4.


So my speaker making journey started trying to find a suitable 12" driver, mean while learning what all these words and numbers mean.

Anyway, after countless hours of browsing i have narrowed to 2 drives, having in mind Fs ~20-22hz of the original 128H, coil size and travel, at least what i understand as a total noob.

- Monacor SPH-300KE , ~150 euro this one looks to me almost same same as the original, apart paper from kevlar, which does not bother me /now/

-DAYTON REFERENCE HF SUBWOOFER - 8 OHM - 12", more RMS, a bit less sensitive, ~200euro


I am attaching some documents for the enclosure, crossovers, etc.

Any help will be highly appreciated. And yes, i don't want to buy the original 128h and forget,i want to learn sth new and experiment



Meanwhile if sb has some idea on better tweeters and mids for the clone, without going too far from the original concept and sound signature of that speaker. For the future clone i mean.
Click to expand...




Try to get original 128H woofers, no other woofer will sound like it, if you need the suspensions here you can get them


12" Refoam Kit JBL 122, 128, 129 - RFK128 JBL - Speaker Exchange
 
#27
Now we have the L100 Classic and the JBL 4312SE Studio Monitor Bookshelf Loudspeakers, brand new. Probably what i would have bought if i did not have mine.

Have mine JBLs paired with Moscode 300 hybrid amp and ODAC directly integrated and hidden in the amp. Couldn't be more happy with the combo.

People when come at home don't see the set up at all as they blend nicely, but when i put on some music their jaws drop
 
#28
Boyan Silyavski said:
Now we have the L100 Classic and the JBL 4312SE Studio Monitor Bookshelf Loudspeakers, brand new. Probably what i would have bought if i did not have mine.

Have mine JBLs paired with Moscode 300 hybrid amp and ODAC directly integrated and hidden in the amp. Couldn't be more happy with the combo.

People when come at home don't see the set up at all as they blend nicely, but when i put on some music their jaws drop
Click to expand...

Both the L-100 Classic and the 4312SE for me they are not JBL, they are Harman, therefore garbage, they became with the implementation of the titanium tweeter that sounds colored and ugly, not near the L-112 or 4411
Harman did a crime discontinuing JBL's vintage driver components and recone kits, I hate them for that, JBL is JBL cause of their 70's and 80's speakers so why they discontinue, such a stupidity.
 
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