25 replies to this topic

[reko19]

I am planning to use the Data Bus Hub to connect four keypads. Want to confirm that Cat5/6 from data hub to keypad is adequate because some other diagrams indicate min 24awg is required. Also I am not clear what to do with JP1, JP2, and JP3. The datahub instructions say to insert terminating RJ45 into first unused port (no questions here) and to terminate the control at JP3? From what I could gather I need to have a jumper across JP3 because I am only using one data home run. If I were using two data home runs I would leave JP3 alone and use jumper across JP1 on the last device of run 1 and across JP2 on the last device of run 2. Thank you for your help.

[SpaceLeeB]

Wow - you beat me to writing this myself! In the same position as you - trying to make sense of the databus connections... the confusion is compounded with the fact that the Elk documentation refers to the J2/J3 blocks as for "testing" only... even though the databus board comes with the proper jumper cable to use those blocks.

I was wondering if I can have a wireless receiver tied into the databus terminals and then the databus board on J2 or if one precludes the other...

I've tried multiple permutations, and so far keep getting a Lost Comm error on my keypad - powers going to it just fine and I've re-terminated both ends of the connection (cat 5e cable and a rj45 male end at the other) according to their instructions for using 3 pair of the 4 pair wire, but no dice.

Anyone able to help us and clarify what can get connected to where?

Thanks,
SpaceLeeB

[wuench]

If you are using a databus hub, you terminate J3 on the M1 and you put a terminator in the first unused position on the DBH. No other devices on the bus should have their termination jumper set. Do not use J1/J2 on the main panel.

Cat5/6 is fine, it is 24ga, unless you have an extraordinarily long run. You can follow the bus length calculations in the manual to determine if you have exceeded the run.

If you want to connect a device (i.e. the wireless rec) to the bus (and not to the DBH) I think it would be considered a second run. So in that case you would connect it to the databus connectors (NOT J1/J2) terminate it, install terminating plug in DBH and NOT terminate the M1 panel J3.


A bus has two ends, and no matter if there are one or two runs there is only one bus, so only two devices get terminated. If you have one run then the M1 JP3 will be terminated as it is one end of the bus. If you have two runs then the end devices on each run are terminated and the M1 is not because it is technically in the middle of the bus.

Edited by wuench, 31 March 2012 - 09:30 PM.

[Lou Apo]

Don't put too much thought into this. The m1dbh is simply a daisy chaining device. You will notice 4 wires are needed for each device, but cat5 has 8. That is becuase the daisy chaining goes from dbh to device on 4 wires, then back to dbh on the other 4, then out to next device, back to dbh, and so on. You can use the first unused spot on the dbh to terminate the run, or, if you want to use all the spots on the dbh for devices, then terminate the last device as per the non-dbh terminating protocol. You will notice, the terminating rj45 jack just has a 120 ohm resistor that shorts two of the wires, the same as you would do at the end of a run using one of the jumpers.

You can also run a second set of devices in parrallel off of the RS 485 port along side the dbh set of devices. In this case, you no longer jumper jp3. This is how I have my setup. All of my dbh slots are used by devices, the last is jumpered and I have one more device in parrallel to the dbh off of the main board and it is terminated. JP3 is left open.

So in short, the dbh is treated as a single line of homerunned devices.

Keep in mind, that since the dbh runs the signal out and back with each device, you need to double the feet. The max is 4000ft so that leaves you 2000ft of actual cat5. And yes, cat5 is perfect for the job and is spec'd by Elk as such.

[reko19]

Thanks guys. I have dbh connected to J1 on M1, JP3 is jumpered and everything works. I also tried connecting dbh to data bus connection above J1 and J2 and it also works fine. I have an additional question. Planning to have a speaker next to each KP for a total of four. Manual says if connecting more than 2 use series/ parallel wiring to avoid going below 4 ohm. I ran 4/22 to each location. So I need to have two parallel runs each consisting of two speakers in series? Does that makes sence?

[Lou Apo]

When speakers are run in series, the ohms add up. When in parrallel, they are 1/a + 1/b = 1/total

You can't really go wrong putting them all in series. If the ohms go too low (as when in parrallel) the current rises and at some point it will exceed the max allowable current and fry the system. The only downside to wiring all in series is that you can't individually control volume or turn individual ones on/off. There are devices that allow you to connect all of your speakers to a hub which maintaines minimum needed resistance and gives you individual volume control. But if you plan on having all of them always on a the same volume, there is no need.

[reko19]

When speakers are run in series, the ohms add up. When in parrallel, they are 1/a + 1/b = 1/total
You can't really go wrong putting them all in series. If the ohms go too low (as when in parrallel) the current rises and at some point it will exceed the max allowable current and fry the system. The only downside to wiring all in series is that you can't individually control volume or turn individual ones on/off. There are devices that allow you to connect all of your speakers to a hub which maintaines minimum needed resistance and gives you individual volume control. But if you plan on having all of them always on a the same volume, there is no need.

I looked at the speaker, they are 32ohms each so even if all 4 of them are in parallel I am at 8 ohms. If I go with the way I described it in the above post I should be at 32 ohms. Either way should be fine.

[DELInstallations]

If you're installing SPF12's (judging by the impedence listed) then installing 4 in parallel will deliver an 8 ohm load to the panel.

If you're installing them in series, the load will be 32*4, so 128 ohms. Given that sort of loading on an amp, it's likely bad things could happen to the panel, if they work at all.

[Lou Apo]

If you're installing SPF12's (judging by the impedence listed) then installing 4 in parallel will deliver an 8 ohm load to the panel.

If you're installing them in series, the load will be 32*4, so 128 ohms. Given that sort of loading on an amp, it's likely bad things could happen to the panel, if they work at all.

Yes, as mentioned, 4 in parrallel is 8 ohms if each is 32 ohms. Elk specs say it is ok to go down to 4, so you are clear. 128 ohms would not harm the elk, but it might not produce good sound. To illustrate, take the example of a disconnected speaker jack, that is infinity ohms, which is more than 128 and that doesn't hurt anything. But I suspect the lack of current from 128 ohms would produce crappy or non-existent sound.

[DELInstallations]

If you run an amp with infinity ohms/no load or too high a load, then provide a signal to it so it's pushing an output, it's very easy to let the magic smoke out, no different than running to low an impedance. It's why higher end amps always tell you to always have a proper load attached, nothing to do with sound quality.

I've (unfortunately) had this happen with a receiver at my house and my little ones as well as dealt with the after effects on very large audio installs and pro touring rigs. No load on an amp, with the output section cranked can, and typically will, damage the amp. Minor impedance mismatches, if done to the "high" side are safer than a low impedance mismatch.

[Lou Apo]

If you run an amp with infinity ohms/no load or too high a load, then provide a signal to it so it's pushing an output, it's very easy to let the magic smoke out, no different than running to low an impedance. It's why higher end amps always tell you to always have a proper load attached, nothing to do with sound quality.

I've (unfortunately) had this happen with a receiver at my house and my little ones as well as dealt with the after effects on very large audio installs and pro touring rigs. No load on an amp, with the output section cranked can, and typically will, damage the amp. Minor impedance mismatches, if done to the "high" side are safer than a low impedance mismatch.

This is just not true. A solid state amp will not be damaged by too high of impedence. At some point it will fail to deliver any power to the speakers but it won't cause any damage. A tube amp is different, but unless you have a 40 year old amp at home or you buy those eclectic $10,000 tube amps at the "I have more money than I know what to do with" stores, you won't fry your amp with too much impedence. In general, solid state amps are damaged by current, tube amps are damaged by voltage, and I am quite certain the Elk has no tubes.

Impedence matching has 2 functions, 1) to not damage the amp and 2) get the most efficient use of power out of the amp. With solid state amps, not going too high adresses by point 2, and not going too low addresses point 1.

Edited by Lou Apo, 02 April 2012 - 07:41 AM.

[ecborgoyn]

In fact, some amplifiers incorporate relays on the outputs that delay the connection of the speakers. This assures that the speakers to not experience the power-up transient from the amps. The relays can also be to disconnect the speakers due to an overload or fault condition at the amp.

[DELInstallations]

This is just not true. A solid state amp will not be damaged by too high of impedence. At some point it will fail to deliver any power to the speakers but it won't cause any damage. A tube amp is different, but unless you have a 40 year old amp at home or you buy those eclectic $10,000 tube amps at the "I have more money than I know what to do with" stores, you won't fry your amp with too much impedence. In general, solid state amps are damaged by current, tube amps are damaged by voltage, and I am quite certain the Elk has no tubes.

Impedence matching has 2 functions, 1) to not damage the amp and 2) get the most efficient use of power out of the amp. With solid state amps, not going too high adresses by point 2, and not going too low addresses point 1.

Lou, the statement is incorrect. What you or someone else chooses to do with their equipment is one thing, but failure to understand impedance and what the effect of too high or too low a load does to the equipment is where the magic smoke gets let out of hardware.

Barring an amplifier's protection circuit, which is another discussion and design criteria for a product, too high a load will cause voltages inside the amp to be too high, which can damage power output tubes or transistors. I have a site I am working on where the electricians did exactly what you said wouldn't damage equipment....they tied too many speakers in a non-coupled mass notification system together in series. They blew up half a rack of amps.

[Lou Apo]

Del,

Tubes yes, but the Elk is not "tubed", and for all intents and purposes, nothing has a tube anymore. Solid state amps are not damaged by high impedence. As indicated, that is exactly why the amps actually purposely disconnect the speakers if they detect a short. . . to protect themselves. Solid state amps need to be protected from run away current, not lack of current. By your logic, an amp that is turned on with no speakers connected and left that way would smoke. But they do not. Furthermore, read the hifi stereo literature and there will be no mention of taking care not to over impede the system, only under. And these same articles will say, "but if you have a tube amp the opposite is true". In fact, just turning a tube amp on without speakers connected can damage them, but this is not the case for solid state.

Perhaps if you have high impedence, you don't get good volume, so you turn the volume all the way up to the top and leave it that way for a long time, that might fry your amp. But that is not really an impedence issue, that is simply that you are using too small of an amplifier for the task at hand. The same thing would happen at lower impedence if you turned it all the way and left it that way.

[Work2Play]

In these large commercial settings, wouldn't 70V speakers be used anyways? Unless you're talking concert halls; but 70V is the preferred method for most larger commercial installs. That has to change things.

Something isn't adding up... Maybe I'll disconnect my speakers and crank my amp and leave it all day (I already ordered a replacement) - I doubt any harm will come.