Used JBL a Active crossovers for sale on + second hand hifi sites & shops. Use Hifi Shark to monitor pricing and global availability. I have found a jbl a crossover that is an improved version of the jbl , but the jbl a should be used with a woofer of 8 ohm instead. These were part of a speaker system that was installed in a church in the vaulted ceilings back in the 70’s. They were treated very well while they were.
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This fall, another big speaker project was not at the top of my list.
But after helping my Technician Steve out with reducing his vast, vintage inventory, he brought me over to his place and after a few hours of moving inventory I came home with some less than perfect JBL pro cabs. As Steve had almost everything I needed to put in them, I thought what the hell I will give them a complete makeover and try my hand at veneering.
The cabinets were so bad from being moved around for 30 yearsstadiums, theaters, bandswho knows the true history and how many ears have listened to them over the years.
JBL Frequency Dividing Network Crossover 3110A
They resembled plywood that you would see at a construction site. Resembling the piece of wood they use as a ramp to maneuver a jbll barrow full of concrete through the uneven terrain. Where do I start? I decided to listen to them first. Yet, they had potential. Anyone familiar with these cabs knows they were bass horns, two ways with the addition of the horn on top. The port configuration changed slightly over the years, but always two on top and two on the bottom. I decided to go more modern with Titanium diaphragms in drivers.
The cosmetics of Steve’s ‘s were much nicer and I knew where they had been. Also, he had the JBL Titanium jbo installed for me. With that, I decided to go with 8 OHM woofers and found some 3110a near 31100a condition, H 15″ drivers. They have a great reputation and are very well regarded in the JBL community. Then, the newer A crossover was needed for the 8 OHM load of the woofer. They look like new, old stock. Also, I liked the option of the extra control on the A.
It has the original 3 position, rotary dial for mid and high control and an added 3 position toggle switch for high frequency boost.
In the meantime, I gutted the cabs. Old insulation out, cleaned them, disinfected them, and sealed the insides with poly and black paint.
Getting rid of all the “old” smell to smell like new! The outside was going to be a challenge. To veneer, one must have a smooth surface to adhere to and these were far from smooth.
I chose to cut the corners back 2″ and replace all 16 corners rather than trying to build them up. New wood, glued and nailed made for a stronger corner. The unevenness of the wood and seriously gouged edges led me to doing some “Bondo” work. But, I needed something for the overall surface of the cabs.
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I had just done some work refinishing myrustic, Douglas fir floors upstairs in my house and had some expensive hardwood floor filler left. It was perfect for skimming and building up the surface back to square and flat. All sides, tops, bottoms, and joints were re-nailed and glued where needed.
This led to 33110a solid cabsdense and vibration free. The cabs were then sanded times and jb, with 3 coats of poly for a glass surface. Now, I needed Steve’s help with the science of cab volume and porting. We were unsure the ports up there were going to help with the bass response at all. So, four custom wood pieces were cut and installed up top.
I had to hand sand the edges to allow for the jgl curve of the horn, and also, beveled the edge so it cosmetically flowed into the horn side. The extra rear crossover port for pro use was blocked off with another piece of wood. I mirror imaged the new crossovers left and right on the cabinets. The bottom two ports on each speaker were blocked and then, new round holes were cut where the existing ones were.
I added two more ports, equally spaced in the middle, to match the port volume of the two I had closed at the top. A round hole allowed me to be able to cover them with trim rings and screens to keep Rover from putting his bone in there and the creatures from reopening the hotel, plus safety of little children.
And the cosmetics are an added bonus. To add cabinet volume, I built two plinth bases out of ribbon striped, 1×4 pine. This helped extend base response and gave the speakers height, putting the horn at the listener’s level. I had already decided on my veneer, which was to be Sapele wood. A species of African Mahogany that is a beautiful ribbon and “J” figured wood.
If it’s good enough for Cadillac, it will work for these! Paint color was going to be something that went well with the Mahogany stain. Paint technology has come a long way. I decided to go with mbl hammered paint on all surfaces that were not veneered. This gives the speaker more of a laminate look instead of painted wood.
The back and front trim 3110a then covered with semi-gloss black. The woofer horn was painted dark, oil rubbed bronze giving a slight contrast to the front black trim.
The Horns and trim rings are done in hammered, burnished amber. It is a gorgeous color that mates very well with the bronze and the mahogany. Now, for the veneer process. It was new to me.
With such a large surface, my patient wife helped me apply it. It works like a charm. Easy to smooth out, cut, and sand. Mine had been cut that week and had not been rolled up for more than four days. With three large sheets, I 3110z able to match the grain from top to sides, and the sides on each speaker have the identical peak patterns.
jbl with or a network
Five hours jjbl, I was ready to stain. Two coats of Mahogany were applied, but not too dark to cover the exotic ribbon grain. Then, four coats of “Tung Oil Finish” were applied. Results are somewhere in between semi-gloss and gloss, but softer than poly. It brings out the grain better and shows the drastic shimmer of the ribbon grain from different angles. Now after dry time, it was time to get the 31110a upstairs. When your wife is out of town for a week, take advantage. Ramps were set up, drivers out extra 50lbsand on the two wheeler around the house I went.
After many hours and something nuts, bolts, washers, and screws, they were ready for a listen. My ears were more than astonished. These were true audiophile speakers. A little 31100a on the crossover and they were set.
One of the biggest drawbacks to this cabinet style was “limited bass response”. It is not the case anymore. The restructuring jhl the ports and the extra riser base made a world of difference.
I know my L’s start to roll off at around 30 Hz and these were right there. I did not change the settings on my preamp so I could have a point of reference on my initial listen.
Huge sound stage, with incredible dispersion. 3110aa on an Alnico magnetwhat a smooth detailed combo. The woofers cut deep, but controlled and punchy. These are a true Audiophile speaker with a unique retro look.
They are too big for my room and I will be selling these great speakers. This was not complete Audio Idiocy, but a very successful project. But for now the L’s sit in the wings, listening to these stunning speakers will keep more than satisfied until the snow is gone. The most important aspect of this project is that my wife will have her car in the garage for the winter and if you live in Minnesota, you know what that means.
Feature story on Audiogon. Well it started a long time ago with me buying two speaker cabinets from the 50’s to take on as jbk restoration and modification project. Very cool walnut cabs jvl swivel bases and flip up lids. I had a vision.
The Setchell Carlson AM receiver and turntable were removed from the one cabinet and the other speaker’s top was for record storage. The inside tops were fitted with mirrored shelves and the speaker baffles and drivers were removed.
A rear firing tweeter was mounted jl the back along with the 3 way crossover network put inside. The tweeter, horn, and crossover networks came from Cerwin Vega Rs, which were designed with a rear firing tweeter. The horns were painted copper and given custom mounts to hold them in place. The cabinets were refinished in a Mahogany stain with a semi gloss poly finish.