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passive crossover and biamping, peavey 3020 speakers


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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

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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

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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.

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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! facepalm.gif
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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! facepalm.gif
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.
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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.

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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.

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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
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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.

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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.

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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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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 wink.gif

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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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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

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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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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.

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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 {censored} Sherlock!!! I learned plenty from that excercise, you can be sure of that. Changed my underwear a few times as well.

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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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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?
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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 {censored} 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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