The Vintage JBL West Coast Sound becomes the…

[Whitey80]

Better photo of them set up. After playing around, these 1st models sound far better upright. Imaging was funky on their sides.

 

[GranteedEV]

And would the driver arrangement of the JBL LSR6332 cause similar issues? If not, why is the LSR6332 different?

It's only an issue if you put the tweeter/mid section sideways, because you then get a different lobe arriving at your two ears. This issue also exists with most M-T-M center channel speakers.

FWIW, the LSR6332 also offsets the drivers and uses large format roundovers on the corners, which both serve to reduce diffraction effects on imaging and frequency response.

I had to look up the LSR6332 to see what it is. Although it and the L100A are both large boxy 3-ways, I doubt if there is much similarity between them. The tools for crossover design have changed significantly since those distant days. The drivers are almost certain to be very different.

Right. The spec sheet shows that the LSR6332 achieves true 4th order acoustic crossover slopes centered at ~250hz and ~2.2khz as well as +/- 1db frequency response and very even off-axis response.

I hope the midrange is smoother that that of the L100.

The paper midrange on the L100...

This is the Kevlar midrange on the modern unit:

If nothing else, i think it's safe to say they're different drivers

I figured this thread might give me some standing to continue the argument. .

Nice try

 

[CAJBL]

So after stumbling upon the Murphy L100 crossover a while back I began to read the posts in numerous forums about other peoples builds and experiences with them, until one day I had the urge to go ahead an build a set for myself. It helped that I had a "project" set of L100's that I wanted to make use off.
Overall, following the schematics building the crossover was very straightforward. What I didnt expect was how much better these speakers actually sound. I know there is still a little bump in the midbass but I tend to like that. I eventually plan on building a new enclosure for a more purist set of monitors, but until then I am loving these speakers. Tested them with Steely Dan Aja, Roger Waters Amused to Death, and an ELP compilation and I am floored by the difference. On the title track of Amused to Death I can actually listen at concert level and instead of my ears bleeding I am able to hear detail that had been lost in the chaos of the original speakers. If I get tired of the midbass I might try plugging the port, but I don't foresee that happening. I have a set of 4411's to compare to and the only noticeable difference is in the high frequency response, but I may try an 035ti to see if that yields an improvement over the LE25-2.
So in conclusion, I am impressed. This crossover brings the L100 to a different level.

https://drive.google.com/file/d/0B3Dkppjs7ieEblJRSEdVUlkyX28/edit?usp=sharing

 

[Swerd]

Thanks telling us your experience with your revitalized L100s, and thanks for the crossover board photo.

I realized I never posted a photo of my board. I took this photo before soldering and attaching the various wires.

Remember, if you replace the tweeter, you will need a new tweeter filter on the crossover. At first, I thought I would have to replace the tweeter, but I was surprised at how good it sounded, even thought the frequency response curve doesn't look good above 10 kHz.

CAJBL had asked if I knew what cabinet volume would work better for the JBL 123A woofer. If anyone is interested in building a whole new cabinet, this woofer works much better in a larger sealed cabinet. (The L100 cabinet is about 1.6 ft³ ported.) Here are some suggested cabinet volumes.

	Q = 0.7	Q = 0.8	Q = 0.9	Q = 1.0
V box (L)	166.7	109.4	76.5	56.8
V box (ft³)	5.9	3.9	2.7	2.0
F3 (Hz)	38.8	44.4	50.5	56.7

<tbody>
</tbody>

 

[Alex2507]

That's a huge box for a .7 Q.

Generally speaking, would a ported box make a speaker behave in a similar fashion?

I'm seeing the Vb go up and the F3 going down.

 

[Swerd]

That's a huge box for a .7 Q.

Generally speaking, would a ported box make a speaker behave in a similar fashion?

I'm seeing the Vb go up and the F3 going down.

I ran those numbers some time ago, and if I recall, I never ran them for a ported cabinet. If I did, I didn't save that info, probably because it wasn't worth saving. For that JBL woofer, a ported small cabinet of about 1.6 ft³ gave it a large peak centered around 70 Hz. It worked much better in larger sealed cabinets.

I never went lower in Q than 0.7 in a sealed cabinet. The box for Q of 0.5 would be as big as a dog house.

 

[Alex2507]

I asked because I need to figure out what happened to my bass in that Primus mod/hack that I started. I suspect that a larger Vb produces more bass (lower F3). I see that my suspicions are valid with your sealed model and wanted confirmation that I could expect the same with a port. I'm not expecting drastic changes produced by doubling or tripling Vb but more interested in knowing the trend or tendency I can expect from small changes produced by altering Vb.

Before I discovered this DIY community I actually read and understood the subwoofer design chapter in a book called The Car Stereo Cookbook. As it turns out I loaned that book out but I sort of had to do a bunch of math before I got to see the 'trend' I'm hoping I remember correctly. I don't know if I can do all that math again ... I'm not a young man.

 

[Alex2507]

I found a Tom Nousaine article on How Stuffing Works that said: in general the bigger the box, the more low end.

 

[dbear44]

I recently built the crossovers for a pair of L-100's that I got from a friend of mine. Frankly, I've never been a fan of the JBL sound prefering something more linear. I am into vintage gear and wanted a pair of good speakers for my garage (i.e. mancave). It has been a really great project and the improvement is really amazing but I am having some problems getting the midrange right. One of the LE5-2 midranges was blown so I looked into a replacement and ended up buying a re-coned one off of ebay. The problem is they sound vastly different. The original one has a DCR of 5.4 ohm and sounds a bit forward and not terribly smooth. The new one has a DCR of 6.3 ohm and sounds smooth but recessed. This intuitively makes sense, the higher impedence would draw less current for a given voltage across the speaker terminals. I attribute the rough response of the original to a stiff, dried out suspension.

This brings up the point that if the crossover is designed for a specific driver, what are the proper specs for that driver. Specificly, what is the correct DCR for the flattest frequency response? I want to get a nice pair of matched LE5-2's but I want to make sure I get it right this time.

I doubt that it would make much difference with the original x-overs since you can adjust the L-pads to get the balance you want.

 

[Swerd]

I recently built the crossovers for a pair of L-100's that I got from a friend of mine. Frankly, I've never been a fan of the JBL sound prefering something more linear. I am into vintage gear and wanted a pair of good speakers for my garage (i.e. mancave). It has been a really great project and the improvement is really amazing but I am having some problems getting the midrange right. One of the LE5-2 midranges was blown so I looked into a replacement and ended up buying a re-coned one off of ebay. The problem is they sound vastly different. The original one has a DCR of 5.4 ohm and sounds a bit forward and not terribly smooth. The new one has a DCR of 6.3 ohm and sounds smooth but recessed. This intuitively makes sense, the higher impedence would draw less current for a given voltage across the speaker terminals. I attribute the rough response of the original to a stiff, dried out suspension.

This brings up the point that if the crossover is designed for a specific driver, what are the proper specs for that driver. Specificly, what is the correct DCR for the flattest frequency response? I want to get a nice pair of matched LE5-2's but I want to make sure I get it right this time.

I doubt that it would make much difference with the original x-overs since you can adjust the L-pads to get the balance you want.

Which crossover did you build? Was it the original JBL design or a new design such as in this thread?

The original LE5-2 midrange drivers that I had were far from smooth sounding drivers. Here is their raw (unfiltered) frequency response. It took a lot of work before a good crossover design was developed. The volume adjustments from the variable L-pads cannot correct this lack of smooth sound. And that's if they are working. Most L-pads corrode and get noisy, or fail to work at all.

Once it gets reconed important things change. Often drivers also get new voice coils at the same time as reconing. Did yours? This more than likely changed most of the driver's Theile/Small parameters. There were also different versions of this driver produced over the years. It seems like your two mid ranges are essentially different drivers.

DC resistance (DCR) of a driver tells you very little useful information for crossover design. For a mid range driver in a 3-way speaker, you need to know the impedance and SPL across the audio range involved. And this is best measured while the driver is mounted in the intended cabinet. And it is probably better if both mid range drivers have similar performance.

 

[Brast]

Dear Swerd,

Many thanks for taking the time to develop this crossover upgrade and for sharing it with the world.

I’ve recently acquired a set of JBL L100A and I am very impressed with how realistic they sound, especially when it gets to reproducing vocals. I’ve tested various vintage speakers since I started my adventure with HiFi (www.audionostalgia.co.uk), and the L100 are indeed very special (even as an unmodified speakers).

I’m very curious to hear how they will perform with your crossover, but because I live in the UK, I will most likely source the parts from the different supplier than you did. I’ve noticed that there are some resistance discrepancies between the inductors on the schematics and on the part list:

• L1011 Inductor (Steel Core) 2.50mH (Part List 0.16Ω, Schematics 0.5Ω)
• L2071 Inductor (Air Core) 0.55mH (Part List 0.23Ω, Schematics 0.3Ω)
• L2091 Inductor (Air Core) 0.15mH (Part List 0.11Ω, Schematics 0.2Ω)
• L2021 Inductor (Air Core) 0.67mH (Part List 0.4Ω)
• L3021 Inductor (Air Core) 0.20mH (Part List 0.17Ω)

Is this because inductors available from your supplier were only available in these resistances or were the schematics’ values rounded up? Would you be able to let me know which set of resistance parameters matches the original xover design please? I can get inductors with either of these resistances, hence my question.

Also, I’ve noticed that part list shows the 0.67mH inductor, whereas schematics show it as 0.68mH.
Could you let me know which one is the correct value please? Again, I can get hold of both.


Apologies, I’m not trying to be picky, I just want to ensure that I’ll get everything exactly as per your design. I’ve read through the whole thread and did not come across anything regarding these discrepancies, hence my post.

I’m really grateful for all the time and effort that you and Dennis Murphy put into this project. And the fact, that after over 8 years since your initial post you still answer questions regarding this project, is truly admirable!

Best regards,
Brast

 

[Swerd]

Brast – I appreciate your interest in this project, and I'll be glad to answer your questions.

I’m very curious to hear how they will perform with your crossover, but because I live in the UK, I will most likely source the parts from the different supplier than you did. I’ve noticed that there are some resistance discrepancies between the inductors on the schematics and on the part list:

• L1011 Inductor (Steel Core) 2.50mH (Part List 0.16Ω, Schematics 0.5Ω)
• L2071 Inductor (Air Core) 0.55mH (Part List 0.23Ω, Schematics 0.3Ω)
• L2091 Inductor (Air Core) 0.15mH (Part List 0.11Ω, Schematics 0.2Ω)
• L2021 Inductor (Air Core) 0.67mH (Part List 0.4Ω)
• L3021 Inductor (Air Core) 0.20mH (Part List 0.17Ω)

Is this because inductors available from your supplier were only available in these resistances or were the schematics’ values rounded up? Would you be able to let me know which set of resistance parameters matches the original xover design please? I can get inductors with either of these resistances, hence my question.

The resistances for the inductors shown in the schematic diagram were estimated values. Their resistances vary depending on the gauge of the copper wire used to wind the inductor. My parts list shows the wire gauge and resistance that I purchased at the time. For example, the 2.5 mH Steel Core inductor I chose uses 15 gauge wire, and has a resistance of 0.16Ω. For all 5 inductors, I believe I choose those with resistances no greater than indicated in the schematic. Because the price of copper wire has increased over the years, you may find that narrower gauge wire inductors can keep costs lower. The differences in resistance should not matter enough to alter the sound of the speakers.

Please note, in the US we use a wire gauge convention (called American Wire Gauge, or AWG) that may differ from what is available to you. Go to this web page https://en.wikipedia.org/wiki/American_wire_gauge, scroll down, and you'll see a table showing wire gauges and diameters.

15 AWG = 1.45 mm
16 AWG = 1.29 mm
19 AWG = 0.91 mm

Also, I’ve noticed that part list shows the 0.67mH inductor, whereas schematics show it as 0.68mH.
Could you let me know which one is the correct value please? Again, I can get hold of both.

The difference between 0.68 or 0.67 mH is too small to matter. I chose the 0.67 mH inductor because it was available. As long as the parts you choose have values (mH for inductors, µF for capacitors, or ohms for resistors) within 10% of the values shown in the schematic, it will not matter at all.

I hope that helps.

 

[Brast]

Swerd - thank you for the prompt and comprehensive reply.

The resistances for the inductors shown in the schematic diagram were estimated values. Their resistances vary depending on the gauge of the copper wire used to wind the inductor. My parts list shows the wire gauge and resistance that I purchased at the time.

From my limited understanding of the crossover design, I was always under the impression that resistance of inductors matters a lot and it is taken into account when designing crossovers. Generally speaking, the lower the better, as long as this was considered during the design process.

So in your schematics, in the low pass section, in series with the woofer, the 2.5mH inductor has a resistance of 0.5Ω. In you project, you've used a much better quality one, with 68% lower resistance (0.16Ω). My question is - does this not upset the balance of the sound? I.e. the woofer outputting more that it was originally anticipated?

Because the price of copper wire has increased over the years, you may find that narrower gauge wire inductors can keep costs lower. The differences in resistance should not matter enough to alter the sound of the speakers.

Yes, unfortunately low resistance inductors are quite pricey, but I have a supplier that can provide 20 different resistance options (different wire gauges & coil sizes) for nearly any given induction.

Speaking of copper. I recall when as a teenager I was helping my dad winding coils for low pas filters, for his speakers (Visaton Atlas DSM). Because he was obsessed with low resistance and really wanted air core inductors, we were using 2.5mm copper wire... if I remember correctly each inductor ended up weighin over 3kg...

Please note, in the US we use a wire gauge convention (called American Wire Gauge, or AWG) that may differ from what is available to you. Go to this web pagehttps://en.wikipedia.org/wiki/American_wire_gauge, scroll down, and you'll see a table showing wire gauges and diameters.

Yes, correct, cable gauges in Europe are usually given in diameter of wire in mm. Thanks for the conversion chart.

The difference between 0.68 or 0.67 mH is too small to matter. I chose the 0.67 mH inductor because it was available. As long as the parts you choose have values (mH for inductors, µF for capacitors, or ohms for resistors) within 10% of the values shown in the schematic, it will not matter at all.

Ok. Noted - thank you. I've got more option for the 0.68mH value, so I will stick with this.

 

[Swerd]

From my limited understanding of the crossover design, I was always under the impression that resistance of inductors matters a lot and it is taken into account when designing crossovers. Generally speaking, the lower the better, as long as this was considered during the design process.

The software used to create that original schematic showed inductance values and an estimated resistance, but did not indicate a wire gauge. That choice is yours.

I wouldn't go so far as to say inductor resistance matters a lot, instead I'd say resistance of inductors matters, so long as it isn't too high. Inductor resistance is only part of the overall AC impedance of the entire crossover network. An inductor's resistance is less important than it is to use an inductor within 10% of the intended mH value.

So in your schematics, in the low pass section, in series with the woofer, the 2.5mH inductor has a resistance of 0.5Ω. In you project, you've used a much better quality one, with 68% lower resistance (0.16Ω). My question is - does this not upset the balance of the sound? I.e. the woofer outputting more that it was originally anticipated?

No I don't believe it altered the overall balance, but I never tried an inductor with greater resistance. I chose the 2.5 mH 15 AWG steel laminate inductor instead of a 2.5 mH 16 AWG air core inductor because it uses much less copper wire, and is less expensive. All the other smaller inductors were air core, either 16 AWG or 19 AWG as shown in the parts list.

Good luck with your build . Keep us busy with your questions and your progress.

 

[roadrune]

Btw, in europe cables are NOT meassured i diameter, but in the sectional area. E.g. 15awg is 1.5mm2.

 

[Brast]

Swerd - ok, thanks for clarification.

roadrune - my bad, you're righ, it is the sectional area not the diameeter.

 

[Bucknekked]

Swerd:
Dude, what a great post. It gets my DIY juices moving. I will still probably buy new instead of embarking on a DIY project. But that's because of several factors outside of my control and choices I've already made. But, should I decide to put a hometheater back in the family room, I would think DIY on the speakers would be a choice I would try and make happen.

Once again, its measurements and the science of Audioholics that makes this type of project work today so much better than back in the Radio Shack day. Back then, we had no way to meaure and tune our projects. We could emulate someone elses work, but, we couldn't really test and adjust unless you knew someone with some pretty specialized equipment.

Thanks for feeding my audio nerd with this post. I enjoyed it a lot.

 

[Brast]

Swerd, I finished the project couple of months ago but only recently got a chance to document it all. Once again - thank you for your help and prompt answers to my questions.

Apart from doing your crossover (Dennis Murphy), I have also purchased Troels Grevesen's crossover kit, and I have also done a straight recap with l-pad replacement. Then, I compared the 3 upgrades with each other and an original speakers.

Full description, measurements and photos are published on my website: www.audionostalgia.co.uk/upgrade_jbl_l100_century.php , however, there is quite a lot of it so for the purpose of this forum, here are my summarised thoughts:

Both the TG and your (DM) crossover designs make the speakers a lot more polite, but if I was to choose one, I would definitely go for your (DM) design. It not only sounds better to my ears, but you can make it from whatever components you like, as the schematics are freely available on the internet. However, neither of these designs make the speaker better (IMHO). Of course, they make it measure really well, and they attempt to make it sound like a modern constructions but they aren't the best at it - i.e. there are number of modern speakers capable of outperforming 'upgraded' JBLs. Which brings me to my point - I realised that I like the JBL L100 for what they are, and accept them with their faults. In addition to this I would like to make a point that I'm using the speakers for enjoyment, not for studio monitoring. Ideally, I would like them to measure very well and sound very well too, but if I have to choose, I will always go for the sound (my perception of it) over measurements. Ultimately, does it really matter that original speaker has +9db on the midrange? As long as it puts a smile on my face when I listen and makes me enjoy the music, I don't care.

Therefore, if you want to improve your beloved JBL L100, my advice would be to stick to the original crossover topology, replace the capacitors with better quality ones and definitely replace the variable l-pads with new ones, or even better, replace them with permanent l-pads (resistors).

There are number of people that are really happy with both Mr. Gravesen's and your (Mr. Murphy's) crossovers, and I am not tying to discourage anyone from building these. I am simply sharing my subjective opinion, which clearly shows that we all have different preferences and we all like different things.

Enjoy!

 

[PK Vintage]

They've both been done for nearly a month now. Building the crossovers was straight forward. It was nice having an 11" diameter hole in the cabinet, it let me easily fit all the crossover parts on a 10×7 pegboard. For once no knuckles were scraped or wires broken while trying to cram the crossover board into a very small space.

How do they sound? In a word, excellent! My very first impression when I built the first one, was that the new crossover made the speakers a lot less sensitive. I had expected that, but it was still quite noticeable. But despite that, the new crossover did not suck the life out of those JBLs.

I spent about a week listening to one speaker with the new crossover, comparing it to the other speaker with the old crossover. After adjusting for the change in volume, the new crossover was a clear winner. Both me and my wife agree that the new crossover sounds much better. I tried a wide variety of music that I knew well, including some music where I actually liked the effect that the bright JBL upper-midrange had. The new crossovers eliminate the glare and brightness that I thought I had gotten used to. I remembered that years ago, I used to play with the bass and treble controls, and fiddle with the variable L-pads on the speakers to adjust midrange and tweeter levels, trying without success to control that ear-fatigue-inducing brightness. The new crossover does it much better. It really amazes me how much better speakers sound when the frequency response curve is flat.

Hello. New member here with a small collection of JBL's L100A, L150, L26 and L19. I have many other "East coast" sets, Ditton 66's 25's and 44's, Kappa 8's BA A400. I like the JBL's, I love the bass and listen to all types of music.

I find the L100's are almost addictive, They hit you with an emotion of music that makes you wonder what are they going to do next. It is very odd and something I have not experienced with any other speaker. They can be harsh but they absolutely pound when you want them to. It almost gives me a nervous anxious feeling. But they are fatiguing, no doubt. I would like to build that new crossover and try it. If you would email me that parts list it would be much appreciated.

Regards

 

[Swerd]

I would like to build that new crossover and try it. If you would email me that parts list it would be much appreciated.

The file is attached below. If you can't download it, I'll send it by email. Check your private messages for my email address. Click on the envelope icon in the top banner, on the upper right.