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passive crossover and biamping, peavey 3020 speakers

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  • passive crossover and biamping, peavey 3020 speakers

    i was gifted a pair of peavey 3020 ht speakers, the big honkin ones with two fifteens, two tens, and a horn and super tweeter. i plan to use them for shows where the big rock look and a total lack of worry about what happens to the gear are important.



    the speakers have a full range input, and low, mid, and high inputs as well. i wouldnt really think of biamping these, but..



    the fifteens do not work on the full range input. they work grand on the low input, isolated from everything else. what i'm wondering is this. its no problem for me to power the fifteens with one amp, and the tens/horns with another. the concern i have is, if i plug one amps output into the low input, and the other amps output into the fullrange input, will there be crosstalk? i cant really see how there would be if the low drivers dont play when the fullrange input is used, but i dont want to damage the power amps.



    biamping and running active are not new to me at all, but using the internal crossover partially in a cab is. what does a passive crossover have to isolate the inputs? i'd guess there has to be something but i really dont know.



    thanks,

    mike

  • #2
    If the 15s don't work when you plug into the full range input there is a good chance the switching jacks on the crossover are not working.

    When you go into the BI amp Low jack it switches the feed from the passive crossover off and makes a direct shot to the 15s. Sometimes this jack sticks in this position. When you remove the jack from BI amp Low the switching jack sticks and wont allow a signal to go to the 15s from the full range input. You can try cleaning this jack with electronic contact cleaner or if the jack is bad you can replace it. Pretty common part from peavey. Easy to do if you solder at all.



    If you want to just BI amp the box you'll of course need a crossover and 2 amp channels. I believe the crossover point is 400hz on the 15s. ( It should be listed on the crossover if I remember right) Next as you stated go into the Full Range input for 400hz and above.



    When you go into the BI amp LOW the switching jack removes all connection to the passive crossover so the 2 are not connected in any way. A straight shot to the 15s as you noted.



    Something you can try. Go into the full range input with a full range signal at a low level. Run a 1/4 inch jack in/out in/out quickly in the BI amp LOW jack and see if the 15s try to work. If they do then the jack may need cleaning or replacement.



    I know the 3020 with the matching 4-15 sub would put out quite a bit of thunder in its day. Remember the 15s are rated at 200 watts each or 400 watts total for the 2.



    Dookietwo

    Comment


    • Yuuki
      Yuuki commented
      Editing a comment

      I have run 3020s for many years during the late 80s and throughout the 90s, I also ran them with two bridged CS-800s all night long, held every ounce of it easily. 400watts program is the RMS value in music power which even at that is conservative. They held all of the 1000+watts of power to each I gave them running every genre of music out there. There has yet to be a single cabinet speaker system to beat them in my opinion. Now adays you have to make 10 trips to move everything that could equal the sound. I know this is an old thread, but dang, why cant Peavey make a great product once again. Now that technology is so much better, Imagine what they could make now.

       One thing I did notice, was a mistake made by so many people among other DJ companies, is that they used too small of an amplifier, and constantly burned out the HT94s. They were clipping their amps constantly in larger venues, and they wondered why they were burning out those Super tweeters. 

      I never once had to replace a HT94 with my bridged setup. I felt sorry for the people driving speakers that required a big block engine, but the ignorant minds that used tiny single CS400 and CS800 amps. Its amazing how many do not realize that distortion from a low power amp kills more HT94s than too much power from a high power amp. I used and still do tell them, you wouldnt use a 4cylinder engine to pull a house, when it needs an 8cylinder.  

       

      It seems today, that is not a problem compare to yester-years amps. I would love to get my hands on a set of 3020HTs again, heck, I would settle for a 3020 or better yet, a 3624 from Sonic and do driver and crossover upgrades.

       

      -Kimiko


  • #3
    I think this is almost correct.



    The part that I am reasonably sure is a problem is the fact that the grounds (commons) are not switched on that crossover because bridging and class D and non-ground referenced outputs were rarely used back then. This means that if you plug 2 amps into this common ground crossover, you could have one of several scenarios... it may work ok (like with a common ground referenced amp such as the CS-800), it may cause hum (ground loops between common grounds where the grounding paths are not designed for this operation (many amps), instability and magic snoke (where the amps become unstable and oscillate due to interaction between ground paths and internal global feedback), and just the major release of magic smoke from non-ground referenced amps driving a ground referenced terminal.



    I would be very, very careful if attempting this. It worked ok in the old days because of the limitations in amp topology.
    -------------------------------------------------------------------------------------------------------------------------------------------------------------------
    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


    • #4






      Quote Originally Posted by agedhorse
      View Post

      I think this is almost correct.



      The part that I am reasonably sure is a problem is the fact that the grounds (commons) are not switched on that crossover because bridging and class D and non-ground referenced outputs were rarely used back then. This means that if you plug 2 amps into this common ground crossover, you could have one of several scenarios... it may work ok (like with a common ground referenced amp such as the CS-800), it may cause hum (ground loops between common grounds where the grounding paths are not designed for this operation (many amps), instability and magic snoke (where the amps become unstable and oscillate due to interaction between ground paths and internal global feedback), and just the major release of magic smoke from non-ground referenced amps driving a ground referenced terminal.



      I would be very, very careful if attempting this. It worked ok in the old days because of the limitations in amp topology.




      Pretty easy to check. Just plug 2, 1/4 inch speaker cables into the crossover. 1 to Full range input. The other into Biamp High. Check the other end and see if there is continuity between the 2 grounds. I'm pretty sure the switching jacks break both the + and - feeds to the speakers when going into Bi Amp High. I still have a few spare switching jacks in my gear room. I'll have to check them out.



      Dookietwo



      EDIT:

      I just looked at the jack. It does indeed break both the + and - feed from the crossovers full range signal to the speaker and replaces it with the + and - from the 1/4 inch jack inserted into it. So the amp used to drive the passive crossover and the one driving the woofers ( in this case) are not common ground. I'll post a picture in a bit.



      When you insert a 1/4 inch jack in there is a odd 2 shaped bent pieces of metal that break contact. 1 breaks the - side. The other breaks the + side. The positive and negative signal from the passive crossover are broken and there is no longer any connection to the 1/4 inch jacks tip or ground inserted .

      Pretty neat setup in a way. The down side is its a very tiny connection and the metal is somewhat soft. If someone were to leave a 1/4 inch jack in the plug for a long time the pins don't reconnect or crud gets in them to break the passives crossovers feed. I've changed more than a few of them through the years. I stll have 6 of them kicking around after maybe 20 years!

      Comment


      • #5
        Fairly common for Peavey speaker in this era to have problems with the switch contacts in the jacks. They wear out and need to be replaced ( or wired around).
        Don Boomer

        Comment


        • #6






          Quote Originally Posted by Dookietwo
          View Post

          Pretty easy to check. Just plug 2, 1/4 inch speaker cables into the crossover. 1 to Full range input. The other into Biamp High. Check the other end and see if there is continuity between the 2 grounds. I'm pretty sure the switching jacks break both the + and - feeds to the speakers when going into Bi Amp High. I still have a few spare switching jacks in my gear room. I'll have to check them out.



          Dookietwo



          EDIT:

          I just looked at the jack. It does indeed break both the + and - feed from the crossovers full range signal to the speaker and replaces it with the + and - from the 1/4 inch jack inserted into it. So the amp used to drive the passive crossover and the one driving the woofers ( in this case) are not common ground. I'll post a picture in a bit.



          When you insert a 1/4 inch jack in there is a odd 2 shaped bent pieces of metal that break contact. 1 breaks the - side. The other breaks the + side. The positive and negative signal from the passive crossover are broken and there is no longer any connection to the 1/4 inch jacks tip or ground inserted .

          Pretty neat setup in a way. The down side is its a very tiny connection and the metal is somewhat soft. If someone were to leave a 1/4 inch jack in the plug for a long time the pins don't reconnect or crud gets in them to break the passives crossovers feed. I've changed more than a few of them through the years. I stll have 6 of them kicking around after maybe 20 years!




          This is true ONLY if the sleeve termination is unused. I am fairly certain that many of these products carried the sleeve as a common together and did not use the ring termonal as the ground (minus).



          The OP MUST verify this within the context of the finished crossover and not the jack alone.
          -------------------------------------------------------------------------------------------------------------------------------------------------------------------
          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


          • #7
            My first "real" PA system! I used to use two of the 415 subs with a pair of PM-1200s for a bass amp when going up against Marshall stacks. Guitarists hated that. But I digress...



            I remember trying to bi and tri-amp the tops on a couple of occasions and don't seem to recall life changing differences on this system and was generally happy enough with the built in passive crossover. It may be a different story with the various DSP based speaker management systems available today, but you would be hard pressed to find enough information to set up a comprehensive preset for this system. I did use the Peavey Dynamic System Controller to protect me from myself and I'm sure it saved me from having to replace drivers on more than one occasion.
            I love to sing, and I love to drink scotch. Most people would rather hear me drink scotch.

            Comment


            • #8
              Stupid double post...
              I love to sing, and I love to drink scotch. Most people would rather hear me drink scotch.

              Comment


              • #9
                thanks guys for all the info. i am biamping only because i cant solder..not that i wouldnt, but being blind does have its limitations, and i respect that specially around very hot things..



                i have the crossover, i have the amp channels, i have the rack realestate, so i think i will just run it as is and see what happens. amps in use are a crest 5000 and 4801. now i just gotta tame that ht94 a bit, it seems to be louder than the rest of the box, but that could have been song specific. if i wanted to use eq to turn down everything above eight khz i'm guessing a shelf type eq would be the right way to go?



                again, thanks much. if i keep these, i will most likely set them up with nl4 and keep this biamping configuration, there is probably no good reason to run an nl8 and all the extra amp channels. plus, one six space rack with the two crest amps in it is already stupid heavy..like caster board worthy heavy.

                Comment


                • #10
                  Back in the day, a lot of folks would disconnect the ht94 entirely. That thing could kill any small mammals that got too close.
                  Chief fader ape, wire monkey, mic macaque, and speaker chimp.

                  Comment


                  • #11
                    Oh, would love to see some pics of those big 'ole boxes. Been a loooooooong time since I saw one of those on a stage.
                    Chief fader ape, wire monkey, mic macaque, and speaker chimp.

                    Comment


                    • #12






                      Quote Originally Posted by agedhorse
                      View Post

                      This is true ONLY if the sleeve termination is unused. I am fairly certain that many of these products carried the sleeve as a common together and did not use the ring termonal as the ground (minus).



                      The OP MUST verify this within the context of the finished crossover and not the jack alone.




                      Andy.

                      A speaker cables 1/4 inch end goes in the Bi Amp High 1/4 socket on the passive crossover and breaks both the + and - feeds from the passive crossovers 400hz and below feed. Thats all there is to it. The tip and sleeve are both used on the cable from the 400hz and below amp. There is no way not to. If tip is used for positive or Neg it doesn't matter on the cable going into the Bi Amp Low jack. Its still not in anyway connected now to the passive crossovers 400hz and below signal or common grounded to the crossover through the jack.



                      A simple way to look at it.

                      In a passive split 2 way speaker a passive crossover sends the lows to the woofer and the highs to the horn. If you disconnected the woofer wires coming from the passive crossover, both positive and neg and wired a different amp to the woofer its impossible for the amp driving the woofer and the amp driving the passive crossover - horn to be connected in any way. In this jack the - from the passive crossover is disconnect before it reaches the ring part in the jack that the ring in a 1/4 speaker cable comes in contact with. The positive is disconnect before it reaches the positive (tip) connnector in the jack. The crossover by its design can allow the box to be bi amped, with a passive split above 400hz. or triamped with a passive split between the 22a horn and supper tweeter. This was a selling feature of the box



                      If you'd like send me your mailing address and I'd be happy to send you one of the jacks and you can take a look for yourself.



                      Of course I do know what you are talking about. You see the negative coming in from the pin that is connected to the PC board that ring barrel is made of. The Negative signal from the passive crossover is coming in from a ""different pin"". In the picture of "peavey switching jack ground lift Negative" it is the pin on the left. Not the pin on the top that the barrel is made of as well. When the 1/4 inch plug is inserted the connection is broken from the left pin. Same for the Positive input. In that picture the jack has been turned 180 degrees to get a better look. On the Left side positive is coming in and the connection is broken when the plug is inserted.



                      If you look here at example "D" you can get a better idea as to what I'm talking about.



                      http://en.wikipedia.org/wiki/File:Ph...ck_symbols.png



                      From the top. There are 5 pins on this jack which is the same as the peavey jack.

                      Pin 1 is on top.

                      Pin 2 next one down

                      Etc.



                      The second pin down is used for the POSITIVE coming from the peavey passive crossover. The signal goes out pin 1 and on to the speakers positive terminals.

                      The 3rd pin is the NEGATIVE coming from the peavey passive crossover. This signal goes out Pin 4 and on to the speakers Neg terminal.

                      If you plug a 1/4 inch plug into the jack the tip will touch and push up on the pin 1 connector and break contact with pin 2.

                      This plug will also make contact with pins 4 connector and push it down and away from pin 3s connect point breaking contact with it.

                      So now pins 1 and 4 are making contact with the plug and are feeding the speaker instead of pins 2 and 3 from the passive crossover.

                      The 5 pin is connected to the barrel of the jack but it is not connected to anything ever including the PC board.



                      Again Pin 5 is not connected to anything on the PC board so it just is used as an extra support.



                      I found a picture of the passive crossovers input jacks so maybe you can get a better idea as to what I'm talking about. I'll see if I can find a schematic on line as well.



                      Its hard to explain things like this on the internet but I believe you can understand the circuit now.



                      Doug

                      Comment


                      • #13
                        I have always understood the circuit, I also know that there were many (typically earlier) Peavey crossovers (and to be fair, crossovers by many other manufacturers as well) built with a connection between sleeves (either on the PCB or on a metallic jackplate). There are also plenty of crossovers that have been repaired with non-isolated bushing jacks that can cause the same fault.



                        The problem is that making the assumption that it's not a problem isn't a problem until it IS a problem and then it may be a big and expensive problem. That's why I advised that this issue be absolutely verified. I wouldn't have mentioned it if I hadn't seen this in the field or in units brought in for service.
                        -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                        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


                        • #14
                          you guys are having fun with this one. cool, i'm going to do the speaker cable to speaker cable and test for conductivity.



                          the ht94 is damn loud for what its supposed to do, i could fix it in eq but..if i disconnect it, there is a 24 db crossover point at eight khz, so i would lose everything above eight k. i'd rather do some corrective eq because dance music loves eight k, just not this much.

                          Comment


                          • #15






                            Quote Originally Posted by agedhorse
                            View Post

                            I have always understood the circuit, I also know that there were many (typically earlier) Peavey crossovers (and to be fair, crossovers by many other manufacturers as well) built with a connection between sleeves (either on the PCB or on a metallic jackplate). There are also plenty of crossovers that have been repaired with non-isolated bushing jacks that can cause the same fault.



                            The problem is that making the assumption that it's not a problem isn't a problem until it IS a problem and then it may be a big and expensive problem. That's why I advised that this issue be absolutely verified. I wouldn't have mentioned it if I hadn't seen this in the field or in units brought in for service.




                            True its good to verify. But I did because I can remember when these speakers came out and became discontinued. I worked on these very crossovers. There were only 2 types. The early ones had the 3 pin XLR type full range input as well as the 1/4 inch input and 3 dirrect to speaker jacks. The later ones just had 2 1/4 inch parallel input jacks with the 3 direct to the speaker inputs. In both cases the setups were the same. No problems using different amp types in these inputs as they are ground isolated. We are not talking about "other crossovers in the field" or from "another manufacture" we are talking about these. Have you ever worked on these very crossovers and found the ground connnected to the either on the PCB or on a metallic jackplate? If you did it would be strange because the ground is not connected to the PCB and the Jacks are PLASTIC by design and would not ground to the metallic jackplate.



                            I get your point that all things should be checked out. But at the same time it is ok to ass ume that I'm not the only person with knowledge or enough common sense to look things over. The OP wanted to know how the crossover works and I told him correctly how they work. You didn't. I knew from past experience using and repairing them how they worked. You came in and said in your own way I was wrong. In your words



                            "" I am ""fairly certain"" that many of these products carried the sleeve as a common together and did not use the ring termonal as the ground (minus).

                            The OP MUST verify this within the context of the finished crossover and not the jack alone.



                            The jacks disconnect all contact with the passive crossover including common ground within the crossover.



                            Just admit your wrong, buy me a beer and all is forgiven. :-)



                            Dookietwo

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