Members Jeff Leites Posted August 20, 2014 Members Share Posted August 20, 2014 To make a long story short, around 1966, I had planned to build my own high powered solid state guitar amp. That project never worked out, and I was left with 4 100 watt "life time guaranteed" Jesen musical instrument speakers. Fast forward about 40 years and I bought a Crate "Power Block" amp, and build two 2x12 speaker cabs for the amp. I think I used the setup less than 10 times. Forward several more years... Yesterday I used the speakers to test out a stereo amp I picked up at a surplus store, and I noticed that one of the cabs was lower in volume than the other. I tracked it down to one of the speakers, not being dead, but being considerably lower in volume than the others. Can that sort of speaker problem be repaired? The Jensen company today, isn't the same Jensen company of the 60's, so I'm sure the life time guarantee isn't going to help. Link to comment Share on other sites More sharing options...
Members Vito Corleone Posted August 20, 2014 Members Share Posted August 20, 2014 Post this over in live sound. Might get a quicker/better response? Link to comment Share on other sites More sharing options...
Members Jeff Leites Posted August 21, 2014 Author Members Share Posted August 21, 2014 OK. I posted it over there. BTW, here are pictures of the cabs with my amp and my DIY reverb. 150 watts into 4 12s is way more then I need when jamming with my buddy in the house. Link to comment Share on other sites More sharing options...
Phil O'Keefe Posted August 21, 2014 Share Posted August 21, 2014 Jeff, here in Southern California, the company to contact is Orange County Speaker in Garden Grove - they do speaker repairs and probably have the parts needed for your old Jensens. I've used their services numerous times, and they've always done a great job. Link to comment Share on other sites More sharing options...
Members Jeff Leites Posted August 21, 2014 Author Members Share Posted August 21, 2014 Jeff' date=' here in Southern California, the company to contact is Orange County Speaker in Garden Grove - they do speaker repairs and probably have the parts needed for your old Jensens. I've used their services numerous times, and they've always done a great job. I'll look into it tomorrow. I've had my home stereo, and my vintage Epiphone combo amp speakers re-coned at a place near my home, GSS Speaker Repair Services. I wonder if it will be economically fisable, I can get a new speaker for $60. On the other hand, these Jensens cost me $50 a piece back in '66. Based on the price of gas, that would be like $500 today. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted August 21, 2014 Members Share Posted August 21, 2014 There's a couple of things you should check before you send it in for repair. Make sure the positive and negative speaker posts are wired properly. Maybe you have one out of phase with the other speakers and its sucking air while the others are pushing air making it sound quieter. Next, Since these are vintage speakers, you cant always trust the polarity markings on the speakers. Connect a 9v transistor battery to the speaker jack and make sure all the speakers move in or out together in the same direction. Next, take an ohm meter and make sure the speakers all have the same dc resistance. If they are all 8 ohms speakers they should read about 8 ohms within an ohm or two. If one reads 6 and one reads 15 you may have a 16 ohm speaker mixed in with the other 8 ohm speakers which is going to give you a lower output. Next check the cone. since these speakers have stamped frames, they tend to contour to the mounting surface. if the baffle is warped it may cause the speaker frame to warp and impeded the cone movement. Sometimes you can just loosen the screws and get a difference in speaker volume. I's also pull the speaker and flex the cone by hand. The spider and cone may have had the glue loosen of the spider warp from moisture causing misalignment. The cone should move in and out without rubbing against the magnet. Sometimes with some slight pressure you can flex the cone and get the piston to move freely again. The paper cones do age, heat and moisture (or lack of it) can do funky things. exercising the cone a bit manually can free up allot of issues and bring back its volume. Just be careful. If the paper is rotten you can have the surrounds crack and then you would need to treat that with plastic sealant. If none of that works, You may need a recone or possibly have the magnet regaussed. If the coils read the same then they should be good. All you have left is the mechanical movement or magnet issue. Link to comment Share on other sites More sharing options...
Phil O'Keefe Posted August 21, 2014 Share Posted August 21, 2014 I'll look into it tomorrow. I've had my home stereo, and my vintage Epiphone combo amp speakers re-coned at a place near my home, GSS Speaker Repair Services. I wonder if it will be economically fisable, I can get a new speaker for $60. On the other hand, these Jensens cost me $50 a piece back in '66. Based on the price of gas, that would be like $500 today. My friend, while I use (and like) the new Jensen speakers, there's NOTHING out there like the mid-sixties vintage Jensens. It would be worth it IMHO even if the cost exceeded $100 for the recone and the shipping. Those are classics - it would be a pity to replace one with one of the modern "reproductions"; again, while they're okay, IMO, they don't sound as good as the old ones, nor do they have the same worth / value on the market. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted August 21, 2014 Members Share Posted August 21, 2014 I'm kind of on the fence on whether the old Jensen's really sounded that much better then the new ones. I think the new Alnicos I have are pretty darn good. I have some Mods that sound good but they really don't sound like any vintage Jensen's I can remember. I haven't heard a vintage Jensen alnico in many decades since I used to do amp repairs for a living so I cant really do an A/B comparison. Even if I could find them the paper cones would likely be very worn and even rotten which can make them sound very different then when they were new so I cant even really be sure the new Jensen's don't sound identical to vintage Jensen's when they were new. You have to wonder what the new Jensen's will sound like in 50 years and whether they will change in tone with age and use. They don't lack for output and sound killer with my 68 head. I had (have) a great set of Altecs that came with my 68 Bassman. I used to use those speakers as a yard stick to compare others. I made a new 4X12" baffle for the cab in the 70's so I could run 4X12's. Neither Jensen's or Celestion's came close to matching the Altecs so I always rated them on the medium scale for quality. I saw allot of Utah speakers in that range too. There weren't many speakers to choose from back then though. Most amps that had Jensen's could be improved using better speakers like Altec and JBL. Its all in the tone you want though. Jensen's were very neutral sounding speakers that just did the job well. Most had a decent bright end and good chime tones on the high end and its one of the key elements in what's called the American Sound. British speakers on the other end like the Green Backs had more mids and less highs. They matched well with bright head like a Marshall that could push the highs hard. I found them to sound pretty poor with Fender heads in comparison to Jensen's. Link to comment Share on other sites More sharing options...
Members Jeff Leites Posted August 21, 2014 Author Members Share Posted August 21, 2014 OK, I didn't make that cabinet to come apart easily. I thought I'd just have to take the nuts of that held the speaker down, but I must have overused the Lock-Tite or something. 4 or 5 wouldn't come off. The bolts would just spin. I had to remove the baffle board (24 bolts), then remove the grill cloth covering the speaker to get to the front of the bolts that were countersunk, and patched over so that they wouldn't show. So I had to dig out bolt head patches to get a screwdriver on them. I thought I had them glued in so that they wouldn't spin. I'll use epoxy when I put it back together. Oh yeah, when I pulled the speaker off of the baffle board, half of the cardboard thingy around the edge of the speaker stayed stuck to the baffle board. So getting back to the speaker problem, I just took it into GSS, and got a quick diagnosis. The cone was frozen due to a magnet shift. I don't know how something like that happens, but while he was working on an estimate, I mentioned that I just might buy a new $60 speaker, and he offered to fix it good as new for $75 instead of the usual $95. I figured a rebuild speaker that cost me $50 in the 1960's had to be better than a $60 speaker today, so I went for it. I should have it back the end of next week. Link to comment Share on other sites More sharing options...
Phil O'Keefe Posted August 21, 2014 Share Posted August 21, 2014 Cool deal! Link to comment Share on other sites More sharing options...
Members onelife Posted August 23, 2014 Members Share Posted August 23, 2014 The cone was frozen due to a magnet shift. I don't know how something like that happens, It's usually a result of some impact and the inertia of the magnet causes the shift. Link to comment Share on other sites More sharing options...
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