Any speaker experts around?

[jpcjguy]

Hey all,

I grabbed some speakers from work they were giving away. I have 8 JBL Control 26CT speakers. (I think I can get another 5-6). They were in conference rooms.
Since they are also "PA" speakers, they are 70V/100V system but after some research, it appears you can bypass the transformer to connect the speaker's input wires to a standard stereo amplifier. They currently have 16 ohm impedance - specs to speaker: https://www.jbl.com/CONTROL+26CT-.html
I am out of my depth on amps, resistance, etc.

Video of guy converting:

I debating on using these in the ceiling of the screen porch I am building or in my detached. Attached are some pics of possible locations.
I currently have a SONOS system in the house so ideally I would like to have these part of that. I realize I would need a Connect, Port, or Connect Amp to make that happen....
So am wasting my time, creating more work than it is worth, on the right track, etc?
I can always post them up for sale and use any money toward another solution....

If this is a go, how do I wire them up? Series, Parallel, etc. - do I pick up a cheap amp? how big?

Thoughts?

 

[BobnCO]

No expert but play w speakers (and have had some PA speakers). If you put 2) 16 ohm speakers in parallel they will in theory be 8 ohms; you could probably do up to 4 in parallel going down to 4 ohms (apparently depends on your amp) 16 ohms / 4 = 4 ohms.. but that’s just math, I haven’t done it.

 

[cgrutt]

I don't know alot about Sonos but have been involved in a few installations. Believe a Sonos Port is basically a streamer that takes your audio media and puts it out at RCA level to an amp. If you connect to a 70v amp you should be able to use speakers as they are. If you bypass the internal transformer per video, wouldn't you just then be able to connect directly to your Sonos amp? If speakers are in fact 16 ohm, a pair in parallel should bring you back down to 8 ohms, which I believe Sonos amps are rated for. So four speakers, each pair connected in parallel should be compatible with both line level outputs of your Sonos amp (assuming that's what you have).

ETA - for using 8 speakers, four pairs each wired in series then connected together in parallel will get you 8 ohms for one output of sonos amp.

It gets more complicated for two 8-ohm line level outputs. You need to wire two 16 ohm speakers in parallel for one output. The other output I think you need to use five speakers. Two pairs of 16 ohm wired in parallel gets you 8 ohms. Wire these two pairs (4 speakers) in series to go back to 16 ohms. Then connect that 4-speaker set to one additional 16 ohm speaker in parallel to bring the five speakers back down to 8 ohms. Note this configuration only uses seven speakers.

Believe easiest thing to do (but most expensive) is use Sonos Port and a commercial 70 volt amp and just run the system at 70V.

 

[jpcjguy]

I currently don't have a Sonos Amp/Port - so I am evaluating options for best bang for the buck also
If I buy a Sonos Amp, then I would not need a stand alone amp and could drive the "modified" speakers directly.
If I leave them at 70v, I would need a 70v amplifier and a Sonos Port (no amp included)
If I modify the speakers, I could get a Sonos Port and a "regular" amp

At least I think.....

 

[txvwnut]

I currently don't have a Sonos Amp/Port - so I am evaluating options for best bang for the buck also
If I buy a Sonos Amp, then I would not need a stand alone amp and could drive the "modified" speakers directly.
If I leave them at 70v, I would need a 70v amplifier and a Sonos Port (no amp included)
If I modify the speakers, I could get a Sonos Port and a "regular" amp

At least I think.....

You don't need a 70.7v amp, you'd only need a transformer to step up the output voltage of the amp you are using to a 70.7v line. I did that many times when I used to do commercial sound. As stated above you can remove the transformers and wire them in series parallel or just in parallel to get the ohm rating you need for whatever amp you will be using.

 

[cgrutt]

I currently don't have a Sonos Amp/Port - so I am evaluating options for best bang for the buck also
If I buy a Sonos Amp, then I would not need a stand alone amp and could drive the "modified" speakers directly.
If I leave them at 70v, I would need a 70v amplifier and a Sonos Port (no amp included)
If I modify the speakers, I could get a Sonos Port and a "regular" amp

At least I think.....

Sorry I misunderstood I thought you already had the Sonos amp. If I had those speakers already and was going to use them, I'd buy the Sonos port and a commercial 70v amp and run the speakers as they were designed to be used. 16 ohms (modified?) Isn't common for traditional stereo equipment. The speakers are actually pretty decent for commercial systems and will likely work best with a 70v amp. The amps can be found fairly inexpensively. The port will set you back about $500 though.

 

[CoogarXR]

The nice thing about sticking with 70v is less sensitivity to long runs, you can use smaller wire than a standard 8 ohm run, and you can stack a ton of speakers in parallel without worrying about impedance load math. You just set the speaker wattage taps to match the amp's power rating. 100w amp, 10 speakers at 10w, or 20 speakers at 5w, or 4 speakers at 25w, whatever. It's pretty simple.

 

[jpcjguy]

So the speakers description on the JBL site:
“The Control 26C’s 16 ohm impedance allows use of multiple speakers in parallel without having to use a more expensive constant voltage distributed system.”

And on the spec document says:
Nominal Impedance (26C): 16 ohms (Min Z 16.5 Ω @ 290 Hz)

So if I were to cut out the transformer, does that impact the impedance?

 

[jpcjguy]

So I have figured out that in parallel the speakers impedance reduces - meaning two 16ohm speakers in parallel now has the equivalent of 8ohms.
And that you want to match your impedance to the amp.
So if I wanted to have 8 speakers driven off one amp that is 8ohms , I need to have a combination of series and parallel speaker connections to ideally get to 8ohms?

Can I assume that the 70v/100v transformer is not related to the speaker impedance?

So I can either get a 70v/100v amp and keep the transformer OR cut the transformer out of the circuit on each speaker and use a “regular “ amp and match the impedance?

Am I thinking correctly here?

 

[Metal-Marc]

So I can either get a 70v/100v amp and keep the transformer OR cut the transformer out of the circuit on each speaker and use a “regular “ amp and match the impedance?

70V lines are good for when you have a school, a hospital or a mall to cover, which is not your case, so bypass the transformers. Let's not get down to how this works so we can keep this simple.

Two identical 16 ohms speakers in parallel will get you 8 ohms.

Four identical 16 ohms speakers in parallel will get you 4 ohms.

These speakers can take a lot of watts, so don't be affraid to use a big amplifier.

And use in-wall rated speaker cables.



Here's a trick on how to connect multiple speakers in a room if you want to keep a good stereo image.

 

[Jim_No_Garage]

Here's a trick on how to connect multiple speakers in a room if you want to keep a good stereo image.

That's useful information, thanks for sharing that approach!

 

[jpcjguy]

70V lines are good for when you have a school, a hospital or a mall to cover, which is not your case, so bypass the transformers. Let's not get down to how this works so we can keep this simple.

Two identical 16 ohms speakers in parallel will get you 8 ohms.

Four identical 16 ohms speakers in parallel will get you 4 ohms.

These speakers can take a lot of watts, so don't be affraid to use a big amplifier.

And use in-wall rated speaker cables.



Here's a trick on how to connect multiple speakers in a room if you want to keep a good stereo image.

Thanks for that info!
So I will bypass the transformers - found a great video of what to do:

I am looking to pick up a SONOS amp or port - whatever I can get a deal on

 

[Bad Eye Bill]

Truckloads of info on audio gear and related stuff here.

https://audiokarma.org/forums/index.php

 

[jpcjguy]

So it looks like I might be able to get my hands on the amplifier they used for the speakers (think there might be 2 available).
It is a QSC Model: CMX 300Va
Specs here: https://www.qscaudio.com/resource-files/productresources/amp/cmxa/q_amp_cmxa_specs.pdf
So should I maybe keep them as 70/100 if I can get my hands on them?
Would still need a SONOS port but not the amp....

 

[Citation]

If you can get the 70V amp it will make things easier. If you need a 70V amp I've picked up an Extron XPA amp. I have several and they are very good amps. I originally got a free XPA 1002 (100W into 4ohms, 2 channel). The XPA 2001 (200W, 70V, 1 channel) are frequently under $40 on eBay. The only negative is the connectors are not your standard home stereo stuff. The great thing is these are very efficient class D amps. They draw very little power when not making sounds. They are intended to be left on 24-7. The bigger models often are stereo 70V (XPS 2002). Note, look at the back to verified if you are dealing with a low voltage or 70V model.

However, if you have a traditional receiver, just bypass the transformers.

 

[Metal-Marc]

So should I maybe keep them as 70/100 if I can get my hands on them?

No, you don't want this for a house.

70V speaker output is designed for when you have large buildings with hundreds of feet of speaker wires.

If you get your hands on those amps, just wire the speakers in parallel on the regular output.

https://www.proacousticsusa.com/blo...multi-source-multi-zone-audio-control-systems

https://en.wikipedia.org/wiki/Constant-voltage_speaker_system

 

[Citation]

If you can get the 70V amp it will make things easier. If you need a 70V amp I've picked up an Extron XPA amp. I have several and they are very good amps. I originally got a free XPA 1002 (100W into 4ohms, 2 channel). The XPA 2001 (200W, 70V, 1 channel) are frequently under $40 on eBay. The only negative is the connectors are not your standard home stereo stuff. The great thing is these are very efficient class D amps. They draw very little power when not making sounds. They are intended to be left on 24-7. The bigger models often are stereo 70V (XPS 2002). Note, look at the back to verified if you are dealing with a low voltage or 70V model.

However, if you have a traditional receiver, just bypass the transformers.

Here is a 70V, 200W stereo Extron amp for under $25 (current bid+shipping)
https://www.ebay.com/itm/376732775541 .
(No relation to seller bid at your own risk).

 

[jpcjguy]

No

70V speaker output is designed for when you have large buildings with hundreds of feet of speaker wires.

If you get your hands on those amps, just wire the speakers in parallel on the regular output.

Ah! So if I can get those amps, use them in the non 70v/100v configuration and still modify each speaker?
Is there a difference in sound quality? I get that 70v allows longer wire that is smaller (cheaper), does it matter if I am just 50-75 feet?

 

[Metal-Marc]

Ah! So if I can get those amps, use them in the non 70v/100v configuration and still modify each speaker?

This. QSC make are great amps.

Is there a difference in sound quality?

Yes. 70V lines will not sound as good.

I get that 70v allows longer wire that is smaller (cheaper), does it matter if I am just 50-75 feet?

70V systems are for buildings. Think hospitals, malls, etc, with hundreds or thousands of feet of speaker wires, for generic mono music or PA systems.

Also the amp you might get will only work as mono for all your speakers.

 

[jpcjguy]

This. QSC make are great amps.

Yes. 70V lines will not sound as good.

70V systems are for buildings. Think hospitals, malls, etc, with hundreds or thousands of feet of speaker wires, for generic mono music or PA systems.

Also the amp you might get will only work as mono for all your speakers.

The QSC has stereo mode with both channels driven according to the spec pdf

 

[Metal-Marc]

The QSC has stereo mode with both channels driven according to the spec pdf

Not available if using the 70V line. It's a moot point anyway. Don't use a 70V distribution system in a home.

 

[jpcjguy]

Not available if using the 70V line. It's a moot point anyway. Don't use a 70V distribution system in a home.

So it really is not a big deal if I get my hands on those amps - as I will be converting the speakers then and could use any "standard" receiver/amp..... (although if they are free - why not! )

 

[Metal-Marc]

So it really is not a big deal if I get my hands on those amps

It will be a great deal. Those amps are great, especially if they are free. Just no need to configure your setup for 70V.

 

[CoogarXR]

No, you don't want this for a house.

70V speaker output is designed for when you have large buildings with hundreds of feet of speaker wires.

If you get your hands on those amps, just wire the speakers in parallel on the regular output.

https://www.proacousticsusa.com/blo...multi-source-multi-zone-audio-control-systems

https://en.wikipedia.org/wiki/Constant-voltage_speaker_system

Not to keep jerking the OP back and fourth, but...

Most of the negative points in this wiki are referencing "Inexpensive" and "low-cost" transformers. QSC and JBL are not going to have these issues. I have installed plenty of 70v stuff, and it's come a long way since the old "School PA System" days. The last setup I did was a similar QSC amp and Atlas ceiling speakers in a 40' square meeting room, and it sounds great.

OP- If you buy the amp, just try it out on the bench. Hook up some speakers to the 70v side and see how it sounds. I'm sure it will sound just fine. I have been pleasantly surprised by modern 70v setups.

 

[Metal-Marc]

Not to keep jerking the OP back and fourth, but...

Most of the negative points in this wiki are referencing "Inexpensive" and "low-cost" transformers. QSC and JBL are not going to have these issues. I have installed plenty of 70v stuff, and it's come a long way since the old "School PA System" days. The last setup I did was a similar QSC amp and Atlas ceiling speakers in a 40' square meeting room, and it sounds great.

OP- If you buy the amp, just try it out on the bench. Hook up some speakers to the 70v side and see how it sounds. I'm sure it will sound just fine. I have been pleasantly surprised by modern 70v setups.

... But you are.

Why would you want to install something with no benefits and some real potential downfall?

 

[jpcjguy]

Hey all - I have picked up a Sonos Connect Amp and a Sonos Connect. Bothe are the older (not black) models but new enough to be compatible with Sonos S2 app.
I am thinking using the Connect Amp to control 4 speakers on the porch. It is 36x18 and was thing of just spacing them along the 36’ length in line to get even volume across the porch. Do I alternate L,R,L,R ? What is recommended for this layout?

In the detached I would use the Sonos Connect and pick up an amp for the 8 speakers there. 4 in the lift bay and 4 on the flat ceiling over the rest. Following Metal-Marc image of R and L channels being opposite of each other.

Assuming I get an 8 ohm amp I would wire parallel or series (or combination of) to get the 16 ohm speakers to match the 8 ohm.
As for speaker wire, get in wall rated at 18 gauge? Is that good enough? Or 16?

 

[Citation]

If these are 16ohm speakers then you should be able to wire them in parallel to result in a nominal 8ohm load (impedance in series add, in parallel you do 1/(1/load_1 + 1/load_2) - https://www.digikey.com/en/resource...rsion-calculator-parallel-and-series-resistor). However, if they are 8ohm then wire them in series to avoid a 4 ohm load. As for how L/R wire them, if all the wires run back to the amp you can just experiment and see what you like best. I suspect your alternating pattern is going to work best for the porch.

With the garage you might want to avoid too many speakers. When you have too many speakers you can get delayed audio signals and it can sound like a mess. Ideally you don't want to hear more than two of the speakers at any one time. If you can do just 4 speakers vs 8 that may actually sound better. With lots of speakers you risk getting a muddy sound due to things like time delay, phase cancellation.
This might be of help - I was hunting around for a good article on the topic but I'm not sure I found what I was thinking of...
https://www.sweetwater.com/insync/t...e-aligning-supplemental-speakers-for-your-pa/

I recall this from an event I was at years back. They had a bunch of horn type PA speakers aimed at the outdoor bleachers. When the person talked you would here something almost like rapid echos. It was very distracting. This is also why PA systems at things like train platforms used very directional speakers. They don't want you to hear more than one because that can result in muddy, hard to understand audio. Your garage is not as big as a train platform so the longest time delay isn't going to be as bad. However, it might be big enough to get a muddy sound if you have too many speakers trying to play the same thing (4 left speakers and 4 right speakers).

 

[jpcjguy]

Good point on thinking about delay. I will keep that in mind.
So I found "ceiling speaker layout" tool on https://xtenav.com/ - could actually search for speakers and they had the exact JBL speakers (Control 26CT) in their options, so I played around and put the dimensions of my 10' ceiling area (32x29) and attached are the coverage for 4 and 6 speakers. Thought this was interesting.
Since they are 16ohm speakers - and to get the resistance down to standard 8 ohm, the easiest is to wire 2 speakers in parallel per channel.
So it looks like my options are either:
4 speakers on the flat ceiling and 4 speakers in the lift bay (sloped ceiling)
or
6 speakers on the flat ceiling and 2 speakers in the lift bay
My logic is 8 speakers over 4 channels - keeping with the 2 speakers in parallel concept for 8 ohms. (basically I either go "6 and 2" or "4 and 4" between the 2 areas in my garage, but they will be wired across 4 channels) - hope that makes sense!

There is no easy way to run a layout on the lift bay because of the vaulted ceiling - part of me thinks 4 speakers in that 15x32 space might be much? But 6 speakers in the flat ceiling area also seems like much?
and here I am in analysis paralysis....hahahaha!!!

 

[Citation]

Can you try just hand placing some of the speakers to get an idea how well they might work before doing the install? For example, if you can just hang two of the speakers from ~ where you think they might go see how it sounds. They will sound a bit different since having them in a flat surface vs suspended will affect the sound. However, a few placement experiments might really answer your questions quickly.

 

[jpcjguy]

It is a finished drywall ceiling throughout. Not a fan of poking holes that I have to fix at a later point in time. I also don’t have the speaker wire yet. Trying to get this right the first time and not end up with rolls of leftover stuff. Have enough of that already!

 

[BobnCO]

Well hurry up and get it done so we can see / hear the results!!

 

[dave*99]

I believe the Sonos amp is stable down to 4 ohms. As you have learned, there are series/parallel options for multiple speakers. I saw one mention of 6 speakers in one area of the garage. You can put 3 of your 16 ohm speakers in parallel on a single channel. The impedance will be 5.33 ohms.

 

[Citation]

It is a finished drywall ceiling throughout. Not a fan of poking holes that I have to fix at a later point in time. I also don’t have the speaker wire yet. Trying to get this right the first time and not end up with rolls of leftover stuff. Have enough of that already!

I can't help with the wire part other than perhaps using some extension cords with pig tails shoved into the ends as temp wiring. As for holding the speakers, any tall ladders? You might even try putting the speakers horizontally on a far wall and see if they project into the room. Nothing says they have to go into the ceiling.

 

[dave*99]

I can't help with the wire part other than perhaps using some extension cords with pig tails shoved into the ends as temp wiring. As for holding the speakers, any tall ladders? You might even try putting the speakers horizontally on a far wall and see if they project into the room. Nothing says they have to go into the ceiling.

They are pretty deep - plan accordingly.

 

[jpcjguy]

I believe the Sonos amp is stable down to 4 ohms. As you have learned, there are series/parallel options for multiple speakers. I saw one mention of 6 speakers in one area of the garage. You can put 3 of your 16 ohm speakers in parallel on a single channel. The impedance will be 5.33 ohms.

Since this is the detached garage, my plan is to use the Sonos Connect I have and pick up a dedicated amp for these speakers. Your math of 16/3 to get 5.33 matches mine - but I think I have some flexibility by getting a four or six channel amp to power the 6,8, or possibly 10 speakers in the garage.

Next step would be to figure out what size amp I need based on the speaker wattage:
150 Watts Continuous Program Power
75 Watts Continuous Pink Noise

 

[Citation]

You don't need to match the wattage unless you are planning on running the speakers as loud as possible without spending more on the amp than absolutely needed. Too much amp power isn't an issue unless you overdrive the speakers (over driving with too little amp power also risks damaging the speakers in some cases). Too little power may be OK so long as the amp soft clips.

 

[dave*99]

Since this is the detached garage, my plan is to use the Sonos Connect I have and pick up a dedicated amp for these speakers. Your math of 16/3 to get 5.33 matches mine - but I think I have some flexibility by getting a four or six channel amp to power the 6,8, or possibly 10 speakers in the garage.

Next step would be to figure out what size amp I need based on the speaker wattage:
150 Watts Continuous Program Power
75 Watts Continuous Pink Noise

Don’t make your crazy with channels. Unless you want to separately adjust volume in different sections of the garage. A 2 channel 4 ohm capable amp will easily drive 8 of your 16 ohm speakers.

And the amp will have a higher 4 ohm power output than its 8 ohm output.

Also in large spaces sometimes a mono signal is used. And the 2 channel amp serves 2 areas separately.

What is your budget? I have good luck with the Crown XLI series.

 

[jpcjguy]

Don’t make your crazy with channels. Unless you want to separately adjust volume in different sections of the garage. A 2 channel 4 ohm capable amp will easily drive 8 of your 16 ohm speakers.

And the amp will have a higher 4 ohm power output than its 8 ohm output.

Also in large spaces sometimes a mono signal is used. And the 2 channel amp serves 2 areas separately.

What is your budget? I have good luck with the Crown XLI series.

I was wondering about mono/stereo - being that is for general music all around the garage, how do I arrange the speakers? (assuming I go with the 6 speaker layout above) "Left" down one side and "Right" down the other? or staggered? Since I am not sitting on a couch and constantly moving around - how does that work?

 

[dave*99]

I was wondering about mono/stereo - being that is for general music all around the garage, how do I arrange the speakers? (assuming I go with the 6 speaker layout above) "Left" down one side and "Right" down the other? or staggered? Since I am not sitting on a couch and constantly moving around - how does that work?

Lots of options. You could put 2 speakers on one amp channel in the lift bay and 4 on the flat ceiling on the other amp channel. With a mono signal your balance control becomes your level control for the 2 spaces so both areas can have equal loudness.

Why do this? With ceiling speakers you might be standing directly under one speaker. With a stereo signal you might hear the other channel very weakly. So when AC/DC is ripping a guitar sound from Highway to Hell that pans left / right it just doesn’t sound right.

Stereo mixes are designed so the sound pans left / right. Not far/near. As it would in a large space with ceiling speakers. The fix is mono.

I expect to hear some push back from some folks here. Ultimately it’s your ears and your space.

I have 2 widely spaced speakers by my pool. One amp channel feeds them a mono signal. The other amp channel drives a subwoofer. It sounds great. And I hear all the music even sitting directly in front of one speaker. I’ll be 4 ft from that speaker and 20 feet from the other.

 

[BurtEggley]

get as many as you can, sell them to have the money for what you want in your shop. Most shops up to about 800 sq ft do well with one pair of speakers sitting on shelves. If you have a 3000 sq ft shop then get two pairs. You don't need loud sound in a shop, it will not be pleasant after a short while when you are trying to concentrate on doing something. You want background music. I love music and prefer it to TV / home theatre. I ran a store for a big US audio store chain many years ago. Trust me. You do not want music blasting in your shop nor do you want the hassle of having to ceiling mount speakers all over the place unless the building is big enough for, "Clean up on aisle 9" announcements.