OK!!! That is only a half-day drive (a LONG half-day) !! I used to have couzens near Haymarket, Virginia. One of them still lives on that family farm. A beautiful part of the USA.

 

Everything still working well so far to this point.
I’m still curious to know more about how and why, but I don’t have the authority to just go in and start digging. (after all, they would say “it’s working fine, we won’t need with it”)
So…is there a way to get a number of total load/ohms we’re looking at, at the point of where the Left and Right cables plug into the powered amp mixing board? (Without having to climb up poles and mix it up with bird and spider nests, and bees, to try and find any labels?
Again, I’m hoping one day to get a chance to pull it all down and go back with a new install. I’m sure it would be much better…

 

IF you can disconnect one side of the connection then the amplifier output connection then you can measure the actual resistance. The challenge that I have often experienced in my efforts to measure speaker load resistance is that the meters I have used did not have a low enough full-scale resistance range to provide adequate resolution. So that might be a problem.

 

that is common problem with DMMs and low resistances. one can get better result measuring low resistances by using larger current. LM317T (voltage reference 1.25V) and 12.5 Ohm resistor (or resistor + trimpot) can form rather good 100mA constant current source. with this, DC source measure voltage drop across speaker(s). then resistance is calculated using R=V/I.
so if you measure 768mV, resistance of that speaker group is 7.68 Ohm. making the current source exactly 100mA makes direct interpretation of resistance possible.

 

If the end users believe that "It is working fine", then probably it is actually "working good enough" until it isn't "working good enough." So it might be time to pause and "enjoy watching the show."
That really does happen!!
I have had clients who sometimes did not understand that "something was not right", who insisted that all was OK. SOMETIMES, if it is not a disaster warming up for the big explosion, it really can be better to stop and wait. But not if it is a life critical sort of situation.

 

If the end users believe that "It is working fine", then probably it is actually "working good enough" until it isn't "working good enough." So it might be time to pause and "enjoy watching the show."
That really does happen!!
I have had clients who sometimes did not understand that "something was not right", who insisted that all was OK. SOMETIMES, if it is not a disaster warming up for the big explosion, it really can be better to stop and wait. But not if it is a life critical sort of situation.

A couple weeks or so ago, I ordered a 20 dollar horn speaker to replace a non-working one and installed it. Everything still fine. THEN…couple days ago they called me to ask about that speaker—they are ordering a couple more to add on the ends to help cover the back straightaway section! So…this might be the “straw to break the camel’s back”…Guess I’d better try that testing method you and Panic Mode talked of…I’d hate for them to burn up the powered mixer my wife donated to them…

 

Be nice to know what the impedance is of each speaker and how many are there in total to be connected now.
Also, what the output of the mixer can handle, usually indicated in ohms as well as the speaker impedance.

 

Many of the less expensive trumpet speakers are eight ohms impedance. In addition, many of the longer connections are ten to 20 ohms resistance. IF all of the connections are good.
The better connection scheme is to use that 70.7 volt output found on many PA amplifiers, and then select the desired power level on the individual speaker matching transformers.
That "70.7 volt" terminal would be at the 70 volt level with the amplifier delivering it's rated output power. The concept can be a bit confusing until you realize that it takes most of the math out of speaker matching.

 

Many of the less expensive trumpet speakers are eight ohms impedance. In addition, many of the longer connections are ten to 20 ohms resistance. IF all of the connections are good.
The better connection scheme is to use that 70.7 volt output found on many PA amplifiers, and then select the desired power level on the individual speaker matching transformers.
That "70.7 volt" terminal would be at the 70 volt level with the amplifier delivering it's rated output power. The concept can be a bit confusing until you realize that it takes most of the math out of speaker matching.

Hmmm…this amp/mixer is what we typically use for live band shows, so no 70v accommodation…guess we might start looking around for a true PA mixer that is set up with the 70v. I saw one last year at my wife’s little church, as I was helping them figure it all out. (It was already hooked up for ceiling speakers—it was a former funeral home.)

 

At a smaller race track itmay be that an actual mixer is not the best choice. But if that is what they already have, and it is working, not needing repairs, it should work for the application.
I recall that the speakers plug into whatever amp you are using, so I am guessing that there is no way to set the amplifier output impedance. I am also guessing that as long as the speech comes thru clearly that is all that matters. Music thru trumpet speakers seldom sounds good, and any effort to increase the bass end can be damaging to the speakers that are intended for clear speech only. Repairing them by replacing the diaphram is rather tedious, and most trumpet speaker brands do not even sell the replacement parts.
REading the specifications sheets for those speakers can be very educational.

 

At a smaller race track itmay be that an actual mixer is not the best choice. But if that is what they already have, and it is working, not needing repairs, it should work for the application.
I recall that the speakers plug into whatever amp you are using, so I am guessing that there is no way to set the amplifier output impedance. I am also guessing that as long as the speech comes thru clearly that is all that matters. Music thru trumpet speakers seldom sounds good, and any effort to increase the bass end can be damaging to the speakers that are intended for clear speech only. Repairing them by replacing the diaphram is rather tedious, and most trumpet speaker brands do not even sell the replacement parts.
REading the specifications sheets for those speakers can be very educational.

Exactly!
As for spec sheets—I’d say it would be a real struggle…many are so aged and weather-ravaged that labels are hard to see, having to climb to reach them, rusted hardware, bees nests, bird nests…I’m not good at standing on a tall ladder and fighting off mad nesters…lol

 

If you need to increase the speaker impedance for multiple speakers to avoid overloading the amp, you can use an autotransformer type (impedance matching) volume control at the amp output.
Reducing the sound level using one of those increases the impedance seen by the amp output.
Every 3dB reduction in the set sound level increases the apparent impedance by a factor of 2.

Typically those controls reduce the volume level by 2-3dB per step of the control knob.
Thus you would reduce the volume by one step or so for every speaker in parallel to maintain the desired impedance at the amp output.

Alternately you can add a 70.V high power transformer in reverse at the amp output, and then 70.6V transformers at each speaker to step it back down, but that's a more expensive route.

 

Exactly!
As for spec sheets—I’d say it would be a real struggle…many are so aged and weather-ravaged that labels are hard to see, having to climb to reach them, rusted hardware, bees nests, bird nests…I’m not good at standing on a tall ladder and fighting off mad nesters…lol

I meant "reading the spec sheets" for the newly ordered speakers.
Of Course, if the system is producing acceptable results, then probably it is best to not change anything, until there is an actual need.