C35 - homebrew or real deal?

[martin2395]

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.

[audiomagnate]

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]

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]

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]

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]

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]

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.

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]

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]

Thank you so so much info!

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

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]

More pics:











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]

More pics:











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]

The mounting plates for the 075's aren't original, that's for sure.

[audiomagnate]

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]

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]

More pics:











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!