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View Full Version : C35 - homebrew or real deal?



martin2395
04-15-2014, 08:09 AM
I think that they are DIY, what are your opinions?

They are in bad shape but if they are genuine factory built cabs I might restore them, otherwise they will be thrashed en sold for parts as 075's have matching S/N, good DCR and all red seals untouched.
The N2400 networks are damaged.

http://i57.tinypic.com/96j4gm.jpg


http://i57.tinypic.com/m8phfc.jpg

audiomagnate
04-15-2014, 09:53 AM
My guess is home brew too, but a closeup of the actual corner joints would be helpful. My homebrew (I think) C40 doesn't have that cool JBL badge on the back.

Not to hijack this thread, but I wouldn't mind confirmation that mine is a homebrew as well so I have posted a few pics. I know the legs are wrong, (solid brass and not wood with brass tips) and the joints don't look quite right.

martin2395
04-15-2014, 10:01 AM
http://i57.tinypic.com/2dhz14z.jpg

The front panel can be removed to release the cloth btw.

I hope they are DIY because i'm not so keen on throwing away 50 years old JBL cabs.

audiomagnate
04-15-2014, 10:04 AM
http://i57.tinypic.com/2dhz14z.jpg

The front panel can be removed to release the cloth btw.

I guess the previous owner didn't know that! Those joints look like the real deal.

martin2395
04-15-2014, 03:49 PM
I'm very curious if they are factory built cabs, they are sitting outside by now as they smell quite musty.

Some more info:

- Woofers are D130 with s/n close to each other, 075's are a matched pair
- Crossovers are N2400
- There are markings on the inside of the cab saying "L1 / L2 or P2" written with a pencil.
- The grille cloth looks geniune, one speaker still had the "JBL" badge on it.

Also, what is the purpose of the port, is it a kind of bass-reflex? I've seen C35's with a wider and a narrower one.

audiomagnate
04-15-2014, 04:47 PM
I'm very curious if they are factory built cabs, they are sitting outside by now as they smell quite musty.

Some more info:

- Woofers are D130 with s/n close to each other, 075's are a matched pair
- Crossovers are N2400
- There are markings on the inside of the cab saying "L1 / L2 or P2" written with a pencil.
- The grille cloth looks geniune, one speaker still had the "JBL" badge on it.

Also, what is the purpose of the port, is it a kind of bass-reflex? I've seen C35's with a wider and a narrower one.

Yes, that's bass reflex, and I agree the cloth looks right.

Horn Fanatic
04-15-2014, 06:13 PM
I think that they are DIY, what are your opinions?

They are in bad shape but if they are genuine factory built cabs I might restore them, otherwise they will be thrashed en sold for parts as 075's have matching S/N, good DCR and all red seals untouched.
The N2400 networks are damaged.

http://i57.tinypic.com/96j4gm.jpg


http://i57.tinypic.com/m8phfc.jpg

Greetings -

1) The glue joints should be a locking miter if it's an authentic JBL enclosure. The average home brew hobbyists typically wouldn't pony up the dough for an expensive router bit to make that joint. Not only that, but the set up to make that joint is a pain in the ass, even more so for one box.

2) It may not be an issue, but JBL didn't use slot binder head screws to mount dividing networks. Perhaps the original screws were lost, or the unit was found used somewhere.

3) On that note, why is the network mounted up so high on a C35, or is the rear panel upside down? Then the badge would be upside down :-P

4) Most noteworthy, the orientation of the woofer mounting hardware is wrong. JBL as a practice, used four 1/4-20 T-nuts located 45 degrees off the horizontal and vertical axis. Correct me if I'm wrong, but it appears that 10-32 hardware was used to mount the woofer. If that be the case, then perhaps who ever built the enclosure did so and purchased the speaker in the seventies. JBL provided along with an O-ring seal, 10-32 & 1/4-20 mounting hardware.

5) Rhetorical question; was the enclosure built prior to 1965? When did JBL begin to use the rectangle badge on the C35-C38 series enclosures? The reason I'm asking is that the SE400 Energizer made it's debut in 1965, but I don't know when that amp or subsequent generation models were incorporated into speaker enclosures. What I see absent is the plugged Energizer cutout. Did JBL ever provide a rectangle badge with builders plans? As we all know, the JBL serial number date data base is all but lost save for the registry in the Lansing forum.

6) Are the two pine blocks present which are supposed to be affixed to the inside rear panel on either side of the network cutout? JBL added those blocks whether the old grey can or the flanged bezel network networks were used. I do not see any type of fastener that would have been used to secure the blocks, which was typically flat head wood screws, or at the least, nails. A glued butt joint of pine blocks and particle board without some type of fastener from the opposite side would not survive should the enclosure be dropped, especially with a 5 or 6 pound network attached to them.

7) Is there a horizontal stiffener affixed to the inside rear panel center axis? It's approximate dimensions would be 3/4" thick x 20" x 2 3/4", with a 30 or so degree chamfer on the corners.

My inclination is that the enclosure is a clone, all be it well made, but missing some key construction techniques and possibly some parts. This is a problem I have with vintage JBL & ALTEC speakers offered up on Ebay. I have seen systems offered up which have chronological anomalies that can only be explained in one word; Frankenspeaker! Then there are those which appear to be authentically vintage, but in reality were built by someone decades ago who bought JBL, ALTEC, or Jensen plans. In such cases the system has changed hands so many times over the years the truth about it is lost to eternity. Too many auctioneers on Ebay claim that everything they sell with a JBL or ALTEC badge is the real deal. Only one with a trained eye and a working knowledge of vintage speaker enclosure construction would know whether the system is legit, or a knock off.

Recently I got into a pissing match with a chap who was selling a Lansing emblem, claiming it came from the last C34 Jim Lansing worked on before he died. :-P Then there was the guy, in order to create hype for the unit he was selling, claimed that Harry Olson founded RCA. Again, :-P

Everybody on Ebay is a freekin' audio expert!

Good luck,

H.F.

Horn Fanatic
04-15-2014, 07:34 PM
Greetings -

1) The glue joints should be a locking miter if it's an authentic JBL enclosure. The average home brew hobbyists typically wouldn't pony up the dough for an expensive router bit to make that joint. Not only that, but the set up to make that joint is a pain in the ass, even more so for one box.

2) It may not be an issue, but JBL didn't use slot binder head screws to mount dividing networks. Perhaps the original screws were lost, or the unit was found used somewhere.

3) On that note, why is the network mounted up so high on a C35, or is the rear panel upside down? Then the badge would be upside down :-P

4) Most noteworthy, the orientation of the woofer mounting hardware is wrong. JBL as a practice, used four 1/4-20 T-nuts located 45 degrees off the horizontal and vertical axis. Correct me if I'm wrong, but it appears that 10-32 hardware was used to mount the woofer. If that be the case, then perhaps who ever built the enclosure did so and purchased the speaker in the seventies. JBL provided along with an O-ring seal, 10-32 & 1/4-20 mounting hardware.

5) Rhetorical question; was the enclosure built prior to 1965? When did JBL begin to use the rectangle badge on the C35-C38 series enclosures? The reason I'm asking is that the SE400 Energizer made it's debut in 1965, but I don't know when that amp or subsequent generation models were incorporated into speaker enclosures. What I see absent is the plugged Energizer cutout. Did JBL ever provide a rectangle badge with builders plans? As we all know, the JBL serial number date data base is all but lost save for the registry in the Lansing forum.

6) Are the two pine blocks present which are supposed to be affixed to the inside rear panel on either side of the network cutout? JBL added those blocks whether the old grey can or the flanged bezel network networks were used. I do not see any type of fastener that would have been used to secure the blocks, which was typically flat head wood screws, or at the least, nails. A glued butt joint of pine blocks and particle board without some type of fastener from the opposite side would not survive should the enclosure be dropped, especially with a 5 or 6 pound network attached to them.

7) Is there a horizontal stiffener affixed to the inside rear panel center axis? It's approximate dimensions would be 3/4" thick x 20" x 2 3/4", with a 30 or so degree chamfer on the corners.

My inclination is that the enclosure is a clone, all be it well made, but missing some key construction techniques and possibly some parts. This is a problem I have with vintage JBL & ALTEC speakers offered up on Ebay. I have seen systems offered up which have chronological anomalies that can only be explained in one word; Frankenspeaker! Then there are those which appear to be authentically vintage, but in reality were built by someone decades ago who bought JBL, ALTEC, or Jensen plans. In such cases the system has changed hands so many times over the years the truth about it is lost to eternity. Too many auctioneers on Ebay claim that everything they sell with a JBL or ALTEC badge is the real deal. Only one with a trained eye and a working knowledge of vintage speaker enclosure construction would know whether the system is legit, or a knock off.

Recently I got into a pissing match with a chap who was selling a Lansing emblem, claiming it came from the last C34 Jim Lansing worked on before he died. :-P Then there was the guy, in order to create hype for the unit he was selling, claimed that Harry Olson founded RCA. Again, :-P

Everybody on Ebay is a freekin' audio expert!

Good luck,

H.F.

One more thing;

The acoustical fabrics speaker manufacturers used in the fifties was made of cellulose, very flammable. New fire codes dictated a non-flammable material be used when installed in commercial buildings. The particular weave and pattern that matches the material on your cabinet is called Oxblood with stripe. The old material was thicker and more rigid than the comparable material Wendell Fabrics produces today, and doesn't stretch easily. I'm sure you have seen some JBL, ALTEC, and Jensen speakers with the gold or silver Cobweb pattern screen on the grille fabric. The inks used today will not stick to the new polyester material as it did with the cellulose material. The new polyester fabric bends and stretches easily around sharp corners. If the material on your cabinet is thin, stretchy and flexible, chances are it's a clone.

martin2395
04-15-2014, 11:39 PM
Thank you so so much info! :bouncy:

I will post more foto's this afternoon.

Btw, look at these, they look almost the same als mine! (expect for the paint and woofer mounting then):
http://www.2dehands.be/audio-video-tv/audio-apparatuur/luidspreker/jbl-c35-vintage-studio-monitors-186033
241.html (http://www.2dehands.be/audio-video-tv/audio-apparatuur/luidspreker/jbl-c35-vintage-studio-monitors-186033241.html)

The network and badge placement is the same, also the reflex port and the screws on the back are identical.
I wonder if this is a kind of a late production model? My woofers have S/n around 82000-83000 and so do the tweeters.

martin2395
04-16-2014, 03:01 AM
More pics:

http://i60.tinypic.com/27ycxvn.jpg

http://i57.tinypic.com/jb5yef.jpg

http://i60.tinypic.com/afbkad.jpg


http://i57.tinypic.com/2wd841i.jpg


If they are knockoffs, i must admit that they are amazingly well built. However I'm starting to think that this an original, late production C35, the s/n of the cab itself is 22633

audiomagnate
04-16-2014, 04:22 AM
More pics:

http://i60.tinypic.com/27ycxvn.jpg

http://i57.tinypic.com/jb5yef.jpg

http://i60.tinypic.com/afbkad.jpg


http://i57.tinypic.com/2wd841i.jpg


If they are knockoffs, i must admit that they are amazingly well built. However I'm starting to think that this an original, late production C35, the s/n of the cab itself is 22633

That looks pretty homebrew to me.

martin2395
04-16-2014, 04:36 AM
The mounting plates for the 075's aren't original, that's for sure.

audiomagnate
04-16-2014, 06:45 AM
Factory built speakers don't have or need penciled cutting marks like that. Those are home made for sure. Now what about my C40, or do I have to start my own thread to get a response?

martin2395
04-16-2014, 07:05 AM
Hmm...I thnk I saw cutting marks on the inside of my 4343 where the cabs are 1000% genuine, will have to compare it later.

Horn Fanatic
04-16-2014, 09:24 AM
More pics:

http://i60.tinypic.com/27ycxvn.jpg

http://i57.tinypic.com/jb5yef.jpg

http://i60.tinypic.com/afbkad.jpg


http://i57.tinypic.com/2wd841i.jpg


If they are knockoffs, i must admit that they are amazingly well built. However I'm starting to think that this an original, late production C35, the s/n of the cab itself is 22633

Well, the mounting holes threw me for a loop, however, the rear cleat doesn't make sense. I'm looking at a JBL C37 drawing at the moment, and the mounting holes are at 45 degrees. Also, JBL was keen on using pine for miter blocks and stiffeners, not floor underlayment. My drawing also indicates no cleat of any kind adjacent to the vent. The pencil lines are puzzling also. From a production standpoint, one would think those who built JBL cabinetry wouldn't reinvent the wheel for every order. If I make more than three of anything I fabricate jigs and templates so I won't need to resort to making repetitive measurements, and I'm pretty sure JBL made more than three C35 cabinets. As I stated in my previous post, your cabinet is well made be it original or not. Perhaps it is original, but deep in my heart of hearts I believe it to be a clone.

BTW - I couldn't help but notice what appears to be the initials H L on the baffle next to the insulation. Perhaps Jim's kid sister Hermoine made the baffle :-P

Ciao!

martin2395
04-16-2014, 09:44 AM
Well, the piece of plywood that holds the 075's went straight to the dustbin as it was probably made at night by a drunk as the hole wasn't even centered :D

I decided to give them a new life and I've already cleaned the inside, threw away the old dampening material, glued + screwed the front panels tightly as I don't need these to be removable.
I'm also planning to build new grilles that will be held in place with velcro, just like 4343 ones for example.

Very hard to tell if these are original or knockoffs as they had genuine cloth, logo's, screws (except the modified woofer and tweeter mounting) and all drivers with serial numbers close to each other.

audiomagnate
04-16-2014, 12:46 PM
...BTW - I couldn't help but notice what appears to be the initials H L on the baffle next to the insulation. Perhaps Jim's kid sister Hermoine made the baffle :-P Ciao!

I can see the eBay listing now: "All original JBL C35s, cabinets lovingly hand assembled and signed by Hermoine Lansing $15,000"

martin2395
04-16-2014, 01:40 PM
Who knows :D:D:D

Nah, just kidding. I bought those C35 just for fun but I'm sure my parents won't be happy to see another pair of "coffins" in the room :applaud:
I need to fix those cabs asap en get the them to my room upstairs before they return home :D

By the way - what would be the best way to fill all the extra holes they drilled for the woofer? I'm planning to leave only the 4 original ones.

audiomagnate
04-16-2014, 04:12 PM
I used to use powdered wood putty for that. Just add water. Have you hooked them up? If so, how do they sound?

Horn Fanatic
04-16-2014, 10:52 PM
i can see the ebay listing now: "all original jbl c35s, cabinets lovingly hand assembled and signed by hermoine lansing $15,000"

roflmao !!!

Horn Fanatic
04-16-2014, 10:59 PM
I used to use powdered wood putty for that. Just add water. Have you hooked them up? If so, how do they sound?

Personally, I prefer the sound of Hartsfields over the sound of powdered wood putty and water, but that's just me.:blink:

Horn Fanatic
04-17-2014, 12:49 AM
Factory built speakers don't have or need penciled cutting marks like that. Those are home made for sure. Now what about my C40, or do I have to start my own thread to get a response?

Post more photos if you can, I have in my hand the C40 drawing package. There are a couple of things that look odd.

audiomagnate
04-17-2014, 11:06 AM
Who knows :D:D:D

Nah, just kidding. I bought those C35 just for fun but I'm sure my parents won't be happy to see another pair of "coffins" in the room :applaud:
I need to fix those cabs asap en get the them to my room upstairs before they return home :D

By the way - what would be the best way to fill all the extra holes they drilled for the woofer? I'm planning to leave only the 4 original ones.

http://www.amazon.com/Durham-Donald-Putty-168-Wood/dp/B0000DI7X7/ref=sr_1_2?ie=UTF8&qid=1397757900&sr=8-2&keywords=water+putty

This stuff dries rock hard and doesn't shrink. I know $1.50 US is a little pricey, but maybe ther's a cheaper Dutch version.

martin2395
04-17-2014, 11:24 AM
What, $1.50 pricey? :eek: A tube of wood filler (or polyester based one) costs something around €10 here.
That's one of the reasons I'd rather live in the USA....much better tools, materials and normal prices.

I think I'd just saw a piece of MDF and mix the shavings with wood glue.

Been working hard last days ;) As you can see one cab is already painted with grey base paint and the second one still needs to be sanded.
I'm still looking for a nice color, something really retro to match the style of the C35. The front panel will be painted matte black, just like the originals.

http://nl.tinypic.com/r/160ye5i/8

Horn Fanatic
04-17-2014, 12:44 PM
http://www.amazon.com/Durham-Donald-Putty-168-Wood/dp/B0000DI7X7/ref=sr_1_2?ie=UTF8&qid=1397757900&sr=8-2&keywords=water+putty

This stuff dries rock hard and doesn't shrink. I know $1.50 US is a little pricey, but maybe there's a cheaper Dutch version.

A luthier friend of mine told me the Durham material is what Fender used back in the day for the fret dots on rosewood fret boards.

martin2395
04-17-2014, 01:48 PM
By the way - how does the N2400 work? D130 goes full range and the 075 starts at 2400Hz?
Ii'm getting strange reading on my impedance meter when I try to measure the crossover at the terminals - HF section gives around 12 ohms and LF gives open circuit.

Horn Fanatic
04-17-2014, 03:47 PM
By the way - how does the N2400 work? D130 goes full range and the 075 starts at 2400Hz?
Ii'm getting strange reading on my impedance meter when I try to measure the crossover at the terminals - HF section gives around 12 ohms and LF gives open circuit.

http://www.jblproservice.com/pdf/Network%20Schematics/N2400.pdf

It appears that the N2400 is a second order network, hence the D130 would not be running full range.

Are you using an actual impedance meter, or a VOM? Impedance is frequency dependent, and a standard VOM by itself cannot tell you what the impedance is, only the DCR.

Very pricy;

http://www.toaelectronics.com/products/zm-104a.html

http://www.amazon.com/dp/B0006TZ4UG/ref=asc_df_B0006TZ4UG3078930?smid=A385A0XNQBW8HY&tag=pgmp-391-100-20&linkCode=asn&creative=395109&creativeASIN=B0006TZ4UG

H.F.

martin2395
04-17-2014, 04:05 PM
I was measuring the DCR, exactly :D

The networks look unmolested except for the two 5W resistors (plain ceramic type) that are partially black, also the piece of foam that was around them has melted slightly. This applies for both N2400's.

I looked around on the internet and was kinda surprised that I couldn't find any 5W resitors and 6mf caps. They are all like 4.7 - > 5.6 - > 6.5 and so on.

audiomagnate
04-17-2014, 05:01 PM
What, $1.50 pricey? :eek: A tube of wood filler (or polyester based one) costs something around 10 here.
That's one of the reasons I'd rather live in the USA....much better tools, materials and normal prices.

I think I'd just saw a piece of MDF and mix the shavings with wood glue.

Been working hard last days ;) As you can see one cab is already painted with grey base paint and the second one still needs to be sanded.
I'm still looking for a nice color, something really retro to match the style of the C35. The front panel will be painted matte black, just like the originals.

http://nl.tinypic.com/r/160ye5i/8


I was kidding about the price. It works much better than sawdust/woodglue. Maybe there's European equivalent.

Horn Fanatic
04-17-2014, 05:38 PM
I was measuring the DCR, exactly :D

The networks look unmolested except for the two 5W resistors (plain ceramic type) that are partially black, also the piece of foam that was around them has melted slightly. This applies for both N2400's.

I looked around on the internet and was kinda surprised that I couldn't find any 5W resitors and 6mf caps. They are all like 4.7 - > 5.6 - > 6.5 and so on.

The resistor value on the schematic is 5 ohm / 1 watt, not 5 watt. At any rate, those resistors are just pads, and they don't HAVE to be 1 watt. They can be 5 or 10 watts. It's the resistance value which is important. If those networks were mine I would do away with that silly variable L-Pad and use a fixed pad of proper value to match the sensitivity of the bullet & woofer. As far as I'm concerned, there is no need of a variable L-Pad in a properly designed crossover network. It's just another gain robbing device in the circuit with a knob that will end up getting lost or broken. :-(

I read somewhere on the internet that Hermione Lansing never used variable L-Pads in her personal crossover networks. If it's on the internet, it must be true. :-P

BTW - That 2.4K crossover point isn't carved in stone, it's probably rounded off anyway.

Try these folks for crossover parts;

https://www.solen.ca/pub/index.php?s1=1&a=2

Ciao!

audiomagnate
04-17-2014, 11:51 PM
...I read somewhere on the internet that Hermione Lansing never used variable L-Pads in her personal crossover networks...

I learn so much here!

If they were mine, because the cabs aren't factory, I would sell the JBL crossovers for big $, plug the remaining hole and make simple new ones without l pads. They'll sound better, still look cool after your skilled cabinet restoration, and be a blast to listen to and to show off to your crazy jenever guzzling buddies. Everybody wins!

martin2395
04-18-2014, 01:59 AM
jenver guzzling buddies, LOL! :D

I don't really think that those networks are worth anything :dont-know: also to be honest I like the way they look.

Odd
04-18-2014, 03:54 AM
jenver guzzling buddies, LOL! :D

I don't really think that those networks are worth anything :dont-know: also to be honest I like the way they look.


The N2400 Revealed (http://www.audioheritage.org/vbulletin/showthread.php?12938-The-N2400-Revealed)

audiomagnate
04-18-2014, 05:17 AM
jenver guzzling buddies, LOL!

I don't really think that those networks are worth anything :dont-know: also to be honest I like the way they look.

EBay says they're worth between $90 and $225. That will buy a lot of "coffee" in one of your famous "coffeeshops" wink wink :D

martin2395
04-18-2014, 07:14 AM
The cabs have the priority by now, when they're done I will give them a listen and see what to do with the networks.