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passive crossover and biamping, peavey 3020 speakers

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  • #16
    I have worked on these (or something that looked the same) when I serviced Peavey, that's why I mentioned it.



    It's also not uncommon for there to be different versions or revisions of a crossover addressing product changes and correcting issues that may have come up during production. It's possible that they were originally designed with common ground and somebody realized that it was not a good idea after they were out for a while.



    You may think things are black and white, but that is so far from reality in the real world. That's why it's important to verify that what is thought or assumed is in fact true in this particular case where I know that there are variations.



    I'm good with the beer thing of course
    -------------------------------------------------------------------------------------------------------------------------------------------------------------------
    Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

    Currently product development engineer: Mesa Boogie

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    • #17
      Well I thought I lived in the real world... Maybe not?



      I donated a Kidney to my brother in 2006 but if you don't tell anyone I'd be happy to sneak a beer or 2 with you. On my tab.

      Someday there should be a hamony-central get together so we all can exchange war stories.

      Later;

      Doug

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      • #18
        By real world, I mean exposure to hundreds of units in a service and support setting. I serviced my fair share of Peavey products, and I remember this being a problem quite a few years ago. I wouldn't have mentioned it if I hadn't known anything about it. The correction involved changing jacks to plastic bushing, cutting some traces and installing some jumpers.



        Here is the Peavey part that would cause the trouble in a metal jack plate: http://www.speakerrepair.com/page/pr...ch/32-103.html



        Any of these parts would cause the problem in an early crossover PCB with the sleeve's tied together even with a plastic jack plate.



        I don't have any of my old Peavey service info, but I recall a service notice that addressed this specific problem (probably across a number of products). It would have been from the late 1980's or early middle 1990's
        -------------------------------------------------------------------------------------------------------------------------------------------------------------------
        Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

        Currently product development engineer: Mesa Boogie

        Comment


        • #19
          If you look at your link the part is noted as



          "There are 4 options available, """plastic housing""" w/4 or 5 pins, and """metal housing""" w/ 4 or 5 pins. When ordering, be sure to check your jack to """match your needs exactly""". These are """not interchangable.''"



          Its up to the person doing the repair to get the correct jack. Some are sold with metal housing and some with a plastic housing. The speakers Mike have use the plastic jack housing on the direct ins. They always have. If you have seen some 3020s with metal housing direct in jacks please include a link or photo.

          I remember way back with the first SP1 type speakers came out that there were metal jacks all around. But those where changed over before the lines end. Of course we are not talking about the first sp1 lines. I do know when the first SP2 and later speakers in that line came out around 1978 there was for sure plastic jacks on the direct ins for ground isolation. They had a sort of metal look but a plastic center. Kind of like the two on the right in the 1820 photo. Also if you look close at the picture I posted of the crossover on the outside you can see the plastic as well used on the 3 direct in jacks even with metal nuts to tighten them up to keep from making contact with the metal frame.

          I do know if you order switching jacks for speaker crossovers "from peavey" you'll get the plastic type as in the photo I took of one of mine for the speakers the OP asked about. I've put these very ones in the OPs type speakers.Other speaker lines or types are not part of this discussion. We need to stay on topic in order for our replies to the OP to be relevant.



          We can hammer away at this all night if you want but it won't change anything in regards to the question Mike asked.



          I'm going over to the Peavey forum and cross post this. Maybe Marty can chime in.



          Doug

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          • #20
            They have used the different jacks in the evolution of their crossovers. For Spotty's benefit I mentioned that he needs to check carefully (he is blind so for his benefit I was being extra careful knowing he likes to play around with different set-ups) and I would hate to find out that something was not right and end up with bigger problems.



            In general, when working on older equipment, or any equipment where the specs may not be clear, or there is suspicion that the specs might not be accurate, to test and verify. Every system and installation that I build up, I test and verify that each component operates as expected and there are no undocumented running changes that might affect the system. Specifically things like I/O interfaces, replacement of internal analog processing with DSP, etc. I have been burned enough over the years to spend the additional time in the shop to save in the field where labor is much more costly.



            Recently, there was a discussion about a Crown amp that the manufacturer's literature said did not have DSP, but MY experience was that there was indeed DSP buried in there but not called out as DSP. In fact, it is DSP and has the latency to support my suspician which is why I called it out originally. This can be a big problem when dis-similar amps are used in an install and coherency tests are performed. Something jumping out of (or back) a flown cluster because of an unexpected 3 or 4msec of latency is not what I want to discover out in the field.
            -------------------------------------------------------------------------------------------------------------------------------------------------------------------
            Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

            Currently product development engineer: Mesa Boogie

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            • #21
              I just remembered something along these lines that makes for another good example.



              I was working on a (large) channel switching bass amp quite a few years ago and choose to use some solid state analog switches (NC and NO types). For the channel switching, the switches needed to break before make so I tested the samples, verified them to the data sheets and looked at the tolerances... plenty of margin.



              The first production run was fine, no issues but the second production run made all kinds of pops and clicks when switching channels. I was seriously puzzled and I double-checked my timing diagrams and made sure there were no assembly errors. Since there were over a hundred of these amps sitting there from this production run that exhibited this problem, I was pretty darn worried, a lot of money sitting there that couldn't be shipped with a serious flaw that I had no idea what was the cause. Turns out the manufacturer of the switching IC's changed the process on one of them to a new process and the timing changed. They weren't even aware of it, it wasn't reflected in the data sheets but caused an overlap and oscillation. The new part had a different timing and ultimately I had to change every amp to the original part and fortunately our second source never changed the process. Identical part numbers had different timings. Oh **************** Sherlock!!! I learned plenty from that excercise, you can be sure of that. Changed my underwear a few times as well.
              -------------------------------------------------------------------------------------------------------------------------------------------------------------------
              Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

              Currently product development engineer: Mesa Boogie

              Comment


              • #22






                Quote Originally Posted by dedmeet
                View Post

                Back in the day, a lot of folks would disconnect the ht94 entirely. That thing could kill any small mammals that got too close.




                No most guys would just blow them up and forget about it.

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                • #23
                  i really appreciate the dilligence you two are approaching this with, so let me ask one final questian.



                  with two 1/4 to 1/4 cables, or 1/4 to banana plugs as it were, how would i set the multimeter to check for continuity between the two grounds, and would i need to be passing signal through one of the input jacks to create continuity? i want to fire the rig up and set up the dsp/eq tomorrow and will be doing it alone/without someone to read the meter so want to acomplish this tonight. thank god jbl dsc260 dsp units are so simple, i can almost navigate the menues without having to see it.

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                  • #24






                    Quote Originally Posted by spottyaudio
                    View Post

                    i really appreciate the dilligence you two are approaching this with, so let me ask one final questian.



                    with two 1/4 to 1/4 cables, or 1/4 to banana plugs as it were, how would i set the multimeter to check for continuity between the two grounds, and would i need to be passing signal through one of the input jacks to create continuity? i want to fire the rig up and set up the dsp/eq tomorrow and will be doing it alone/without someone to read the meter so want to acomplish this tonight. thank god jbl dsc260 dsp units are so simple, i can almost navigate the menues without having to see it.




                    Continuity test, you can use the audible one if your meter has one.



                    With nothing else connected to the speaker, insert a plug into the low in and high in. There should be no continuity between the sleeves of the two plugs.



                    Do you know how old they are?
                    -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                    Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

                    Currently product development engineer: Mesa Boogie

                    Comment


                    • #25
                      Why not just get the crossovers fixed, run them full range and be done with it? or bypass the crossover to the 15's altogether and put in a new jack, The 15"s just had a 6db per octave low pass filter- the coil probably fell off or got disconnected. people did all kinds of weird **************** to these cabinets back in the day they were the cheapest loudest system you could buy- I saw all kinds of mods to these, one company put in 2" drivers and junked the 22a and the HT94 , i saw another put in a bank of peizos,

                      These boxes were all over tacoma in the 90's

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                      • #26
                        my eventual solution is going to be to get the jacks replaced, but i have a specific show in 1.5 weeks that i got these for, so i just need them to work for that show like this and then i'm going to tear into them and do it right. i dont want to put any more money into these than i have to, and i am pretty sure i wont be keeping them for a long time, though i must admit that putting a 2 driver and horn is damn tempting, if only because i already have such a combo that'd probably fit if i cut the cabs up, but then i'm committed to that path, and i think i'd rather just run em fullrange with stock drivers most of the time and call it a day.

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                        • #27
                          these are older, with the xlr fullrange input on them btw.

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                          • #28
                            I'd have the original crossovers repaired by a qualified tech, triamping these has basically no benefit and could lead to major amp failures. Could be a choke coil became dislodged, could be the 1/4" inputs went bad. It's worth the hassle. Have both serviced at the same time too.
                            www.rock-bot.com
                            Live-Band-Karaoke

                            bassist and sound reinforcement

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                            • #29
                              well, i will update with, andy was right about the ground being common across the two terminals. if i did the test right, which i'm guessing i did because how can you really muck up a continuity test, there is definite signal between the grounds of the low input and the fullrange input, but nothing between the possitives, which i expected.



                              i dont think i have time to service the crossovers before the gig so i am going to get in there and just hard wire the fifteens to the 1/4 jack, which should be interesting as it appears the 1/4 jack is an integral part of the crossover circuit board, and it may prove impossible.



                              any other suggestions to make this work before next tuesday? i have the amps to triamp the system if only for this gig but not the dsp...



                              is there a way to bypass the low input jack with hard wire to make it so the fullrange input drives the fifteens without the option of triamping? its not ideal but it sure would simplify the amp rack. also, it appears the only way to get at the crossover is to pull a fifteen, remove the padding inside, and then go from there..doesnt seem like much fun to me but i gotta do what i gotta do at this point because the drivers/horns i slated for my custom built mid tops are sitting idle while i find a competent carpenter who want run off with my parts and deposit like last time..

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                              • #30
                                i opened them up today, the 1/4 jacks are all board mounted so taking it apart in a way that can be easily put back together is going to be a true pain in the ass. my goal was to see if i could figure out how to simply bypass the low input jack so the fifteens used the crossover, negating the need to triamp. if anyone can give me a pointer on how to do this, wire between traces on the board? anything..i want to be able to undo it though, and fix the crossovers properly after the show.

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