New member! - New JBL C36 acquisition, a few questions regarding restoration.

[aztecsurf]

Hello all! Glad I found this site and looking forward to the group discussions here. I just got a hold of a nice set of JBL C36 speakers. Beautiful Mahogany finish with a few minor scratches.

The only thing I know about these is that they have the N1200 crossover from looking on the back. Consecutive serial numbers as well. I removed the front covers and the drivers are in perfect condition. I will open the back later to identify the rest of the components and model numbers. I fired them up briefly on my receiver and they sound very thin and almost no bass. I am assuming they are going to need the crossovers rebuilt due to age.

I do not know anyone that offers a rebuild service on these in California. I will search the forums here to see if anyone offers that.

I have never owned JBL vintage speakers and would like to get some feedback on the sound once they are in tip top condition. I listen to mainly Jazz and Classic Rock.

How will these sound overall with this type of music? Assuming the driver is decent and working, is the bass response decent? I dont need crazy low bass, just a nice tight punch that sounds correct for the song that was produced. Are the highs too bright?

Anything I should be cautious about before running these after the rebuild? I have a Parasound solid state amp that pushes around 100w per channel to drive them.

Thank you so much for any help or advice you have. I am very excited to get these up and running smooth! I will post pictures later once I get the time to get some good shots.

[Joseph Smith Jr]

Hello all! Glad I found this site and looking forward to the group discussions here. I just got a hold of a nice set of JBL C36 speakers. Beautiful Mahogany finish with a few minor scratches.

The only thing I know about these is that they have the N1200 crossover from looking on the back. Consecutive serial numbers as well. I removed the front covers and the drivers are in perfect condition. I will open the back later to identify the rest of the components and model numbers. I fired them up briefly on my receiver and they sound very thin and almost no bass. I am assuming they are going to need the crossovers rebuilt due to age.

I do not know anyone that offers a rebuild service on these in California. I will search the forums here to see if anyone offers that.

I have never owned JBL vintage speakers and would like to get some feedback on the sound once they are in tip top condition. I listen to mainly Jazz and Classic Rock.

How will these sound overall with this type of music? Assuming the driver is decent and working, is the bass response decent? I dont need crazy low bass, just a nice tight punch that sounds correct for the song that was produced. Are the highs too bright?

Anything I should be cautious about before running these after the rebuild? I have a Parasound solid state amp that pushes around 100w per channel to drive them.

Thank you so much for any help or advice you have. I am very excited to get these up and running smooth! I will post pictures later once I get the time to get some good shots.

Cannot comment on sound without knowing what it is you have
Although you should for proper inspection and diagnosis, you don't have to remove the back, post some photographs of your speakers from the front and people here can tell you exactly what model drivers you have
Low bass output could be something as simple as a lose or corroded wire
You're jumping to conclusions and making assumptions, like that fact that you need a rebuild service
If in fact you do, there are more than a few in Southern California
Joe

[grumpy]

Nice find.

Probably D130A + LE175. Efficient, but not big on very low bass or super highs.
Would expect to sound nice with Jazz/Acoustic. Rock? might work for you.

Crossover isn't definitely an issue, but it seems to be a common way to
dig into and participate with an old bit of history. Might consider just
building (or having built) new crossovers so you don't screw up the value
of an antique... assuming there's something wrong to begin with or you
just have the jones to do so.

[aztecsurf]

I will grab some photos today. Since I am new to these type of speakers I did not really know what to expect as far as sound and the performance in the low, mid, high area. I have several nice sets of speakers ranging from Boston Acoustics, Focal and Monitor Audio. Since I did not hear any bass from the JBL's I wanted to make sure I have checked everything first.

I thought that most internal components have a given shelf life before needing basic service. Since these crossover's are reaching the 50 year mark would it be safe to do a good cleaning on the external parts and just run them to see if they perform? I do want to keep everything in original condition and preserve what they have.

[aztecsurf]

Here they are! I took several shots to show the condition. I do not know what year these were made or if they originally had the wood feet or metal.

[grumpy]

Very nice examples.

Probably similar vintage to what's listed here as an "001" system:
http://www.lansingheritage.org/image...964/page29.jpg

No sound from the 15" driver, or no "bass"? If there's no sound, you've
got some homework (e.g., bypass the crossover and put a signal directly
to the driver).

[aztecsurf]

Very nice examples.

Probably similar vintage to what's listed here as an "001" system:
http://www.lansingheritage.org/image...964/page29.jpg

No sound from the 15" driver, or no "bass"? If there's no sound, you've
got some homework (e.g., bypass the crossover and put a signal directly
to the driver).

There is sound and bass but the bass is very very weak. Like the driver is struggling to produce the low notes. I play the same song on my Monitor Audio's and the bass is clear and crisp. Both JBL's are exhibiting this same lack of sound. Overall the connections look good for the age but I will take some time later and clean the contacts, secure the wiring to make sure.

[Joseph Smith Jr]

Don't know what "very very weak" means
130As will give you plenty of bass, it just won't be very deep but it will be balanced with respect to the top end and tight
There should be no sound of a struggle
Do you have an SPL meter? A test tone CD or record?
There are SPL meter apps for smart phones but I have no idea how well they work
Then you can provide something definitive as for what "weak" means, some sort of meaningful reference
50 years old or not you can certainly clean the connections, the components you have are built to aircraft quality levels in both fit and materials
The spring type terminals on the drivers themselves will cut a fresh spot by simply exercising them a few times on the wire
The weakest link as for bad connections is on the outside at the crossover
Do you have spring or screw terminals on your N1200s?

[aztecsurf]

Don't know what "very very weak" means
130As will give you plenty of bass, it just won't be very deep but it will be balanced with respect to the top end and tight
There should be no sound of a struggle
Do you have an SPL meter? A test tone CD or record?
There are SPL meter apps for smart phones but I have no idea how well they work
Then you can provide something definitive as for what "weak" means, some sort of meaningful reference
50 years old or not you can certainly clean the connections, the components you have are built to aircraft quality levels in both fit and materials
The spring type terminals o the drivers themselves will cut a fresh spot by simply exercising them a few times on the wire
The weakest link as for bad connections is on the outside at the crossover
Do you have spring or screw terminals on your N1200s?

The N1200 terminals are spring. I will grab some deoxit and clean the terminals. I will also try as you mentioned and exercise the wires on the drivers. It sounds like I may be able to get these back to life with these methods noted. That would be fantastic!

[Joseph Smith Jr]

Deoxit on the spring type terminals whose little blades cut pretty good into the bare wire is a waste of time as far as diagnosing your complaints is concerned
Not a waste of time as far as a preventative of sorts and it certainly won't hurt anything but the spring loaded connectors are an excellent design and will provide a positive connection a 100 years from now
Just need to let them get a fresh bite on the wire every 50 years or so

Subjective bass may seem lacking if things are stiff. If these have spent an inordinately long period of time sitting dormant then wake them up gently. The 130A has an all paper cone and surround and needs to be treated with care if it is one of the earlier types without any sort of edge dope.

You can have the edges doped by a professional, you can dope them yourself or you can treat them with alcohol and restore the paper pulp to it's original state of flexibility

Whatever you do, if your woofers are of the untreated variety you need to do something to protect the surrounds or you'll split your cones if you decide to use them regularly

[aztecsurf]

Deoxit on the spring type terminals whose little blades cut pretty good into the bare wire is a waste of time as far as diagnosing your complaints is concerned
Not a waste of time as far as a preventative of sorts and it certainly won't hurt anything but the spring loaded connectors are an excellent design and will provide a positive connection a 100 years from now
Just need to let them get a fresh bite on the wire every 50 years or so

Subjective bass may seem lacking if things are stiff. If these have spent an inordinately long period of time sitting dormant then wake them up gently. The 130A has an all paper cone and surround and needs to be treated with care if it is one of the earlier types without any sort of edge dope.

You can have the edges doped by a professional, you can dope them yourself or you can treat them with alcohol and restore the paper pulp to it's original state of flexibility

Whatever you do, if your woofers are of the untreated variety you need to do something to protect the surrounds or you'll split your cones if you decide to use them regularly

Ok, I will check the 130a's for the dope issue and if they need to be treated, thank you. Good advice.

[aztecsurf]

Speakers are in fantastic condition. I see no issues with the outer part of either 130a. I just realized these are 16 ohm rated. I dont think I have ever had 16 ohm speakers. My amp is rated at 8 ohms. Is this ok to run? Sorry for the basic 101 questions.

[grumpy]

It's safe. Just understand that a solid state (not tube) amp will clip at 1/2 its 8ohm power, so keep that in mind.

[BMWCCA]

As others have said, the 130A is not a bad woofer, it just doesn't produce as much or go as low as other JBL fifteens. The 001 is a polite system that doesn't overdue bass or high-frequencies. There's not really even a tweeter in this system and the LE175DLH doesn't really go that high. I've always thought the C36/38 cabinets were too small to really let the 130A (or even D130) perform as well as they could. The C35 or C37 would be better. Enjoy them for what they are.

Even with a larger box, you'll never walk into a room playing the 001 and get hit with strong bass response. It won't overwhelm you, won't bother your neighbors, or get you in trouble with the police, either. They are what they are. Play some nice strings or guitar over them and appreciate them for what they do well.

[aztecsurf]

Thank you all so much for your advice. I am going to run these at a low volume for a bit, see how they sound after some time. It sounds like these were probably designed to be used with a 16 ohm Tube Amp. That was probably the normal available equipment back then. Perhaps this explains why the sound is a little lacking from my Parasound Solid State amp at 8 ohms. Still I will continue to test and verify that the woofers are in good shape and enjoy the new sound!