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[Chuk Gleason]

Looking for discussion about speaker layouts; lets see if I can describe this.

I've been tasked the last few years with upgrading the audio delivery in some fire stations in my city/employer.  As part of what we call the 'trip-light' system, we have a radio which turns on its speaker when it's paged with a set of sequential tones, and also it trips a relay which turns on light fixtures in the station, so the firemen don't have to fumble for a switch in the dark.  (For old farts, remember the tones on the show "Emergency")

Audio comes out of the radio, to an amp, and then distributes on 70V lines to the speakers.  Speakers in the dorms, apparatus bay, office and day room/dining room/kitchen area.

What i've been doing is this:  All speakers get an individual home-run back to the cabinet with the amp, to common terminal strips, one for + and one for - . This way, if a single speaker blows up or shorts, it can be easily removed from the system just by disconnecting it. 

I've just come across a situation where a station is being renovated, and while I told one of the contractors in meetings what I wanted, he ended up ignoring me, and everything is run on one string, room to room to room, etc.   Still 70V, and the individual speakers are all in parallel with each other, but... it's not what I wanted.    Thru channels, I got a (snarky) comment that 'Normal speaker installation should be parallel.  We did not specifically specify the topology.  The contractor only to install per manufacturer instruction.'

Well, we talked about topology in meetings, no, it didn't get written down or noted in meeting minutes, but what about doing it the way the system designer wants?  Isn't that industry standard, too?

Have I explained it well enough?

What say everyone else?

Thanks,
Chuk

[Scott Holtzman]

Looking for discussion about speaker layouts; lets see if I can describe this.

I've been tasked the last few years with upgrading the audio delivery in some fire stations in my city/employer.  As part of what we call the 'trip-light' system, we have a radio which turns on its speaker when it's paged with a set of sequential tones, and also it trips a relay which turns on light fixtures in the station, so the firemen don't have to fumble for a switch in the dark.  (For old farts, remember the tones on the show "Emergency")

Audio comes out of the radio, to an amp, and then distributes on 70V lines to the speakers.  Speakers in the dorms, apparatus bay, office and day room/dining room/kitchen area.

What i've been doing is this:  All speakers get an individual home-run back to the cabinet with the amp, to common terminal strips, one for + and one for - . This way, if a single speaker blows up or shorts, it can be easily removed from the system just by disconnecting it. 

I've just come across a situation where a station is being renovated, and while I told one of the contractors in meetings what I wanted, he ended up ignoring me, and everything is run on one string, room to room to room, etc.   Still 70V, and the individual speakers are all in parallel with each other, but... it's not what I wanted.    Thru channels, I got a (snarky) comment that 'Normal speaker installation should be parallel.  We did not specifically specify the topology.  The contractor only to install per manufacturer instruction.'

Well, we talked about topology in meetings, no, it didn't get written down or noted in meeting minutes, but what about doing it the way the system designer wants?  Isn't that industry standard, too?

Have I explained it well enough?

What say everyone else?

Thanks,
Chuk

If you didn't get it in writing it didn't happen.  I live on the contractor side, people say all sorts of things in meetings, if it is a change to the spec it needs to be on a change order and the appropriate engineering and financials stakeholders must sign off.

Switching hats around home running a 70v system defeats the purpose and adds extra loss in cabling.  On top of that it's more expensive.

The entire purpose of a 70v system is to use a common bus.

[Ivan Beaver]

If you didn't get it in writing it didn't happen.  I live on the contractor side, people say all sorts of things in meetings, if it is a change to the spec it needs to be on a change order and the appropriate engineering and financials stakeholders must sign off.

EXACTLY

What was in the DRAWINGS?  And were the drawings updated as needed?

It is what is in the "paper trail" that is important.

Documentation is everything in a job.  Without it, it is just a matter of opinion and "he said/she said".

[Cailen Waddell]

Looking for discussion about speaker layouts; lets see if I can describe this.

I've been tasked the last few years with upgrading the audio delivery in some fire stations in my city/employer.  As part of what we call the 'trip-light' system, we have a radio which turns on its speaker when it's paged with a set of sequential tones, and also it trips a relay which turns on light fixtures in the station, so the firemen don't have to fumble for a switch in the dark.  (For old farts, remember the tones on the show "Emergency")

Audio comes out of the radio, to an amp, and then distributes on 70V lines to the speakers.  Speakers in the dorms, apparatus bay, office and day room/dining room/kitchen area.

What i've been doing is this:  All speakers get an individual home-run back to the cabinet with the amp, to common terminal strips, one for + and one for - . This way, if a single speaker blows up or shorts, it can be easily removed from the system just by disconnecting it. 

I've just come across a situation where a station is being renovated, and while I told one of the contractors in meetings what I wanted, he ended up ignoring me, and everything is run on one string, room to room to room, etc.   Still 70V, and the individual speakers are all in parallel with each other, but... it's not what I wanted.    Thru channels, I got a (snarky) comment that 'Normal speaker installation should be parallel.  We did not specifically specify the topology.  The contractor only to install per manufacturer instruction.'

Well, we talked about topology in meetings, no, it didn't get written down or noted in meeting minutes, but what about doing it the way the system designer wants?  Isn't that industry standard, too?

Have I explained it well enough?

What say everyone else?

Thanks,
Chuk

I spend a lot of time in municipal construction meetings...  if the work was an AIA compliant project, I would expect a spec in division 11 of the project manual, where the topology is dictated, along with the rest of the design. There would be sections on installation, methods, verification, training, and handoff.  As well as equipment lists with design basis models and acceptable substitutes etc...

If it isn't on the drawings or plans - it didn't and isn't going to happen no matter what you say or said.  You MIGhT have a leg to stand on if it is in the meeting minutes... but even that is doubtful...

Your engineering/facilities department should be familiar with this stuff.  A specification book is very common in municipal bid work.   They should be able to help you craft your design into a bid spec.  It's really the architects job, along with the electrical engineering firm, but most of them don't know shit about sound... so spoon feed them.  If you give them a written spec, even more likely it will be done correctly....


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[Chuk Gleason]

EXACTLY

What was in the DRAWINGS?  And were the drawings updated as needed?

It is what is in the "paper trail" that is important.

Documentation is everything in a job.  Without it, it is just a matter of opinion and "he said/she said".

OK, I'll grant that this wasn't in the drawings, and that's a bridge that the water has flowed under.  I'm sure there are some not-so-good reasons for them not being; I know the subject was discussed, and there was supposed to be a review before final drawing, which either didn't happen, or didn't get to my level.  This subject is closed; it's a dead end, no good will come of it, etc.

My basic question is standard topologies; are all speakers in one string, thru several rooms, or are individual rooms each a separate chain?  Designer's choice?

[Cailen Waddell]

OK, I'll grant that this wasn't in the drawings, and that's a bridge that the water has flowed under.  I'm sure there are some not-so-good reasons for them not being; I know the subject was discussed, and there was supposed to be a review before final drawing, which either didn't happen, or didn't get to my level.  This subject is closed; it's a dead end, no good will come of it, etc.

My basic question is standard topologies; are all speakers in one string, thru several rooms, or are individual rooms each a separate chain?  Designer's choice?

I'd say designers choice.  In a facility I manage, which has about 80 speakers in it, there are maybe 15 or 20 home runs.  Divided logically, main lobby, basement corridor. East side basement offices and art studios, east side main level offices and studios

That said, i am certain the run organization had more to do with conduit, firewalls, and dealing with as few penetrations as possible.


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[Johannes Halvorsen]

I know very little about this things, so please take this as Curious George question, and not advice or argument:

Wouldn't a serial connection cause the whole system to fail if one speaker fails in the worst way? Wouldn't that, this being the speakers that are supposed to wake sleeping firefighters, be a breach of some regulation?

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[Chuk Gleason]

I know very little about this things, so please take this as Curious George question, and not advice or argument:

Wouldn't a serial connection cause the whole system to fail if one speaker fails in the worst way? Wouldn't that, this being the speakers that are supposed to wake sleeping firefighters, be a breach of some regulation?

Sent fra min SM-G935F via Tapatalk

No problem with the question, Johannes; I'll try to make it clear.

Well, first off, this is where terminology is important. 

Normally and nominally, in a 70 volt system, each speaker is in parallel with all other speakers.  Think of 2 wires going off from the terminals of the amplifier; 1 positive (or hot) and 1 negative (or ground, or perhaps reference).  All speakers along that length are in parallel. 

If you attach another pair of wires to the same amp terminals, the same way, and send them off in another direction, and start adding speakers, those will all be in parallel, too.

(btw, there's another thread where someone came into a venue, and the 70 v. speakers were honestly wired in series.  The plus terminal of the amp went to the plus terminal of the 1st speaker's transformer, the negative terminal of that transformer then went to the plus terminal of the next speaker, etc, etc, 'til you got to the very last transformer, whose negative terminal went, thru the other wire of the cable all the way back to the negative terminal of the amp. Conclusion:  Installer was on something, or just not in his right mind, or was just hired off the street.  Or something.  This arrangement might be used in simple speakers, of impedances like 2 ohms, and then adding up in serial to a total (if for example I suggest 8 speakers total) of 16 ohms. Maybe common in home & car speaker systems, but not in commercial, distributed sound. But that's another discussion.  It was just wrong).

Yes, if all speakers were wired in serial, yes, a failure of one would cause the whole system to fail.  And the FF's would conceivably sleep thru the alert (assuming they don't also wake up for the lights turning on, too.)    2 major failure modes would be a) speaker dead short, in which case in a serial connection, all other speakers would just get a little more power, and b) speaker completely open, which in  a series setup would cause all speakers in that string to not work at all.    If every speaker is in parallel with all others, the opposite happens for each failure - if one speaker shorts, it tries to consume all the power from the amp, shorting out its output.  If one speaker fails open circuit, the amp just acts like the speaker's not there.

Yes, it would be a violation of the regulation that 'I want it to work this specific way, and wake the firefighters from their well-deserved slumbers.' 

Cailen has answered much of the question; several home runs, each run going to a functional area.  My situation, I just have very small individual areas (dorm, apparatus bay, day room, etc. ) 

[Lee Douglas]

I'd say designers choice.  In a facility I manage, which has about 80 speakers in it, there are maybe 15 or 20 home runs.  Divided logically, main lobby, basement corridor. East side basement offices and art studios, east side main level offices and studios

It may be the designers preference, but if it doesn't make it to the RFQ or the riser diagrams for the project, the sub pulling wire has likely bid it to the letter of those documents in order to come up with the lowest bid. If there are no control devices called out and the riser diagram doesn't show individual areas broken out, you're going to get exactly what you got.  The fact that nobody brought it up during Q&A and nobody sought out the designer to clarify the design represented on paper and/or further clarified any changes by documenting them and requesting them to be signed of on, only gives you less (or no) recourse at this point.  If anything, it's kind of back on the OP for not following through after the meetings that were held to make sure that a change order was created, signed and executed.

[Hal Bissinger/COMSYSTEC]

What the OP wanted is called a home run or star configuration. Such an installation, depending on quantity of speakers and building design would be much more costly than the normal tapped line configuration that was installed. Perhaps they did hear you and it was vetoed because of cost? And quite frankly I don't think your way is any more reliable or easier (in the unlikely event) to troubleshoot than what was installed.

-Hal

[Scott Holtzman]

What the OP wanted is called a home run or star configuration. Such an installation, depending on quantity of speakers and building design would be much more costly than the normal tapped line configuration that was installed. Perhaps they did hear you and it was vetoed because of cost? And quite frankly I don't think your way is any more reliable or easier (in the unlikely event) to troubleshoot than what was installed.

-Hal

Agree completely.  Home runs are done for zones, power budget (when the available amplifier power is exhausted) and then the minimum amount of cable, penetrations, boxes etc.  That's basic design criteria.

[Jason Lavoie]

OK, I'll grant that this wasn't in the drawings, and that's a bridge that the water has flowed under.  I'm sure there are some not-so-good reasons for them not being; I know the subject was discussed, and there was supposed to be a review before final drawing, which either didn't happen, or didn't get to my level.  This subject is closed; it's a dead end, no good will come of it, etc.

My basic question is standard topologies; are all speakers in one string, thru several rooms, or are individual rooms each a separate chain?  Designer's choice?

If there is only one amplifier in the design, and no zone switcher or other indication that home runs are required then I would expect the contractor to do whatever is most efficient (sometimes speakers get home run due to conduit layout or convenience, but mostly they would be daisy-chained)

Jason

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