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View Full Version : New member! - New JBL C36 acquisition, a few questions regarding restoration.



aztecsurf
06-07-2016, 11:11 PM
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.:D

Joseph Smith Jr
06-08-2016, 07:26 AM
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.:D
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
06-08-2016, 08:20 AM
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
06-08-2016, 09:57 AM
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
06-08-2016, 10:30 AM
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.7197471975719767197771978

grumpy
06-08-2016, 11:08 AM
Very nice examples.

Probably similar vintage to what's listed here as an "001" system:
http://www.lansingheritage.org/images/jbl/catalogs/1964/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
06-08-2016, 11:34 AM
Very nice examples.

Probably similar vintage to what's listed here as an "001" system:
http://www.lansingheritage.org/images/jbl/catalogs/1964/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
06-08-2016, 12:04 PM
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
06-08-2016, 12:16 PM
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
06-08-2016, 12:59 PM
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
06-08-2016, 03:13 PM
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
06-08-2016, 07:06 PM
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
06-08-2016, 08:04 PM
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
06-08-2016, 08:57 PM
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
06-08-2016, 11:19 PM
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! :)

BMWCCA
06-09-2016, 04:33 AM
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! :)
Shouldn't have much to do with it. I've lived with my 030 system in my house for over 50-years. Only ran with tubes until around 1970 and from then on it's been Crown solid-state amps. They actually came alive more with the Crowns, but then mine are in the C37 cabinets which are a bit larger. :dont-know:

grumpy
06-09-2016, 08:11 AM
right. wouldn't expect the amp to be a problem in terms of overall sound balance.

SEAWOLF97
06-09-2016, 08:26 AM
I recently had a pair of C-38's with the 030 load.

Did not notice any bass deficiencies , and that bullet can peal paint if you'd want. :eek:

aztecsurf
06-09-2016, 12:21 PM
Shouldn't have much to do with it. I've lived with my 030 system in my house for over 50-years. Only ran with tubes until around 1970 and from then on it's been Crown solid-state amps. They actually came alive more with the Crowns, but then mine are in the C37 cabinets which are a bit larger. :dont-know:


I actually have an older tube amp that is rated at 30 watts and 16 Ohm taps on the back. Should be a fun test to see how it sounds. The preamp I have will do separate output to my sub so I can always bring that into the mix for more bass if needed.

grumpy
06-09-2016, 01:34 PM
If it's all working, 30w should be enough to drive you from the room :)

boputnam
06-09-2016, 04:36 PM
Here they are! I took several shots to show the condition. I've not followed this thread closely, but casual inspection of your pictures shows the wiring to the motors is unconventional. Interior is Black to Black speaker, Red to Red speaker - period - if using the OEM network. I've not seen a Blue (solid, to 130A) in a JBL cabinet (original). Likewise, the Grey (solid) to the 175 is someone's homemade ideas.

Now, on the positive side :applaud:, I'm certain both your motors are negative polarity (if OEM - I cannot tell from your pics if they've been reconed/refurbished). So, I think you'd better get your face into the networks and see what's going on, vs what you think is going on...

Joseph Smith Jr
06-09-2016, 04:40 PM
Old JBL, as in old old like yours, nominal system ohm ratings versus individual ratings don't always translate the way they do on most of today's stuff
Your new 001s on solid state taps should be presenting a very kind load to that amp
The amp's not the issue assuming there is one
If your Parasound amp is healthy and rated at 100 watts RMS on the 8 ohm taps, those speakers will blow you out of the room without the amp having to even break a sweat as grumpy has already pointed out

Take a meter and measure the system's nominal DCR and see what it says

Either way the amp isn't the problem unless there's a problem with the amp

Joseph Smith Jr
06-09-2016, 04:49 PM
I've not followed this thread closely, but casual inspection of your pictures shows the wiring to the motors is unconventional. Interior is Black to Black speaker, Red to Red speaker - period - if using the OEM network. I've not seen a Blue (solid, to 130A) in a JBL cabinet (original). Likewise, the Grey (solid) to the 175 is someone's homemade ideas.

Now, on the positive side :applaud:, I'm certain both your motors are negative polarity (if OEM - I cannot tell from your pics if they've been reconed/refurbished). So, I think you'd better get your face into the networks and see what's going on, vs what you think is going on...
I second that emotion, need to see what they've got going on at the network connections
There is a Blue wire on some network versions but I also have never seen one used in the cabinet hook
Doesn't prove anything though in and of itself
I would be a little suspicious too though as for what's going on with the wiring hook up
https://www.soriaudio.com/files/org_files/f_jbl/jbl_n1200_network__schematic_lpnmusic.jpg

Joseph Smith Jr
06-09-2016, 05:40 PM
If you feel as if there is a problem still, you can give this a try, might help you narrow things down
Google can translate the text for you, but the picture pretty much tells the story, best I can tell this guy liked it
http://blog.zaq.ne.jp/lansing/article/70/
http://blog.zaq.ne.jp/lansing/img/img_box/img20080120091548141.jpg

boputnam
06-11-2016, 06:20 PM
There is a Blue wire on some network versions...Yeah, I might have been a bit hasty. I've not seen more than a few C36s myself. That said, the reversed connection on the 175 has my suspicion(s) peaked...

aztecsurf
06-15-2016, 04:06 PM
Good news! So, after some further testing with a strong tube amp I had at 8 ohms the speakers sound much better. To get the bass correct I had to bring it up a bit on my preamp. Normally I dont have to mess with the bass adjustment but with these speakers it was needed. Not a huge amount but a couple of notches up from the base level setting. The high's on these are very good. Jazz of various sorts sounds very smooth, not too bright.

I will have to spend some more time with my music collection now and learn more about these beauties!

Thank you so much for all the help everyone has provided.

On a side note, I did not need to change any of the connections around. Just a change in the amp and bass settings got them to where I wanted them. :)

Joseph Smith Jr
06-17-2016, 09:35 AM
Good news! So, after some further testing with a strong tube amp I had at 8 ohms the speakers sound much better. To get the bass correct I had to bring it up a bit on my preamp. Normally I dont have to mess with the bass adjustment but with these speakers it was needed. Not a huge amount but a couple of notches up from the base level setting. The high's on these are very good. Jazz of various sorts sounds very smooth, not too bright.

I will have to spend some more time with my music collection now and learn more about these beauties!

Thank you so much for all the help everyone has provided.

On a side note, I did not need to change any of the connections around. Just a change in the amp and bass settings got them to where I wanted them. :)
That's good to hear
They will certainly go way loud if that's your thing, but I'd suggest going easy on them at first until things limber up a bit, especially if they have been inactive for any substantial length of time
Things get stiff so you sort of need to break them in again
Overcome that extra little inertia that comes from sitting still for so long if in fact they have
Were these speakers dormant or in storage for a good long while?
Still, go easy at first

Joseph Smith Jr
06-17-2016, 05:06 PM
Speakers are in fantastic condition. I see no issues with the outer part of either 130a.
Are the surrounds treated or not? As mentioned, they made them both ways. If they are of the untreated variety and you play them long enough they will split.
If they are untreated it's easy enough to address - brush the pleated surrounds and about 3/32 of an inch onto the cone, just over the hump where the surround transitions into the cone, with a light coating of the same PVA material sold for re-sealing cloth surrounds
A lazy Susan and a good brush will give you professional looking results
You don't need much