4301B

[taro]

Hi to all; this is my first post.
It was at the end of the seventies when I got a look at JBL. Here in Germany I think JBL was known for live like reproduction of music and from advertising with the pros. From 79' to 84' I bought L50, 4301B, L112, L150A and I liked them all, with the L150A the best. Whish I had them today, because for some reasons I sold everything in the second half of the eighties.
About five years ago the HiFi virus got me again. After various apeakers (diy and factory built) I came across a pair of 4301B, which were in really good condition. With some oiling of the veneer and a kit from Rick for the 116H woofers they looked like I bought them new two weeks ago. They sounded good, not only for nostalgic reasons, especialty in the bass part.
While reading in this forum I found the schematic of the network and decided to change to some better parts. I changed the tiny 1.2 mH iron coil to an air coil with 1.4 mm Wire (0.3 Ohm) and the 0.4 mH iron coil to an air coil with exact the same dcr.
For the caps I took intertechnik MKP's. (15+1.5 and 6.8+0.22). I also added to both 0,01 Vishay Roederstein caps because this can't hurt and they are cheap.
The result was readily audible in the whole range. The already good bass was crisper and clearer as well as the midrange. Subjectiv the LE26 sounded as if it went to 17 or 18k without any harshness.
So for its size and money I think this smallest of the 43xx series can hold its own against many others, new or old.

[Zilch]

Welcome, Taro, and thank you for the beautiful pictures.

4301Bs are a forum favorite!!

[taro]

Thank you. The knowledge base here is great, I learned so much.

[mech986]

Hi Taro and welcome to the Forum also. From the near mint appearence of your 4301B's, it is evident you treat your JBL's well.

I do have one question/caveat. I always thought most crossovers try to keep their inductors away from each other and mounted at right angles with respect to each other (orthogonal). That is to minimize inductor interactions due to current induced magnetic fields. Since these inductors are not self shielding, that may be a consideration - I do know though you don't have much room on the crossover/input connector board to work with.

Regards,

Bart

[boputnam]

...I came across a pair of 4301B, which were in really good condition. ... So for its size and money I think this smallest of the 43xx series can hold its own against many others, new or old.

Whoa, those are some real beauts. Really.

I've two pair in current constant use - shop and officeoffice - and they never cease to amaze me. Interesting idea on updating the crossover - I've only added bypass caps to mine, and that alone was a good improvement.

To me, these remain one of the most surprising offerings from JBL. Too often overshadowed by larger and more complex models - but we all know there are real merits to a two-way, when properly executed.

I maintain that JBL, while surely engineering every model carefully, got really lucky with this one...

[Mr. Widget]

About five years ago the HiFi virus got me again.

Damned hard to shake isn't it.

Welcome aboard!


Widget

[soundboy]

I, too have some mint 4301B's...I love 'em. I left the origonal coils, because I took up the whole board with claritycaps SA series. Huge difference...and, I like the bass the way it is, so I left the old iron cores in there. Didn't want to mess with the Q of the bass at all...I have more transparent speakers, but whenever I fire these up, they always surprise me with how freakin' right it all sounds...I found the L26 tweeter to be surprisingly good after the capacitor change....good luck, and have fun with your bug!

[taro]

Thank you. I think you are right with the stacked coils. I will change that, so there isn't much space. Considerung the Q of the bass you can take an air coil with 0,4 - 0,5 Ohm. This will not change the Q but lower the distortion and will clear things up considering the deviding point is 2,5k.

[boputnam]

'zat a L96 on the stand...? I love that one in the 43xx series - the 4313B.

Try it - you'll like it...

[soundboy]

You are wrong, Taro. Adding ANY resistance raises the Q of the bass rolloff, doesn't matter where the crossover point is. I don't know what the DCR is of the origonal iron cores are...it's on here somewhere, most likely a Giskard post, but I am pretty sure it is less than the equivelant air core....that is why I just left mine intact...the 4301's are famous for their bass already.. You would have to have at least 14 guage wire to even come close to an iron core in low DCR..what I do think, is that your new coils cleaned up the midrange clarity, and probably aren't enough of an increase in DCR to make much difference in the bass ( like you mentioned). Less than a half ohm usually isn't that audible, and won't change the bass bump that much IME. Love those pictures...put it on my desktop, thank you!!!

[majick47]

Taro some great pictures of your 4301b. My second system has a pair of 4301b mounted on the wall useing heavy duty JBL pro brackets in a room that's about 8'x10'. For the size of the speakers they are impressive and my setup probably closely reflects their original pro intent of being designed for monitoring in a small space. Two additional pairs of 4301b are being used in my surround system for the side and rear speakers. Also used heavy duty pro speaker mounting brackets to attach the 4301b to ceiling beams and wall.

[kingjames]

Taro, is that a Mazda ad with naked girls sitting below that crossover?

[taro]

Hi Soundboy, you misunderstood me. I mesured the stock iron 1.2 mH coil, it is about 0.45 Ohm. This is in the range (0.4-0.5) of JBL stock coils, according to some well known people here. The air coil I took has 1.4mm wire and 0.3 Ohm. This slight reduction in resistance tends to make the bass slightly more crisp. The main concern is the air coil makes much less distortion, which is clearly heared because the bass must do the whole range up to 2.5k.
Oh - I didn't have noticed the Madzda ad - you are right.
Thanks taro

[taro]

Hi Bo. Yes, that are L96 on the stands which I bought some month ago. When I got to the seller I had to look twice. The L96's were stored in JBL boxes for over 20 years, and so they looked like they were bought last week at the next dealer. The only thing, when I touched the foam it fell apart. So I dealed up a lower price and took them home. With new surrounds they looked great.
regards taro

[Fangio]

About five years ago the HiFi virus got me again.

Sounds familiar to me. Be warned there is no cure known here so far.

Welcome to Lansing Heritage taro. Looks like some JBLs in exceptional shape you have there.