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connecting old large speakers to amp (4ohm parallels) 1/4" in only?
Old 5th August 2020
  #1
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connecting old large speakers to amp (4ohm parallels) 1/4" in only?

Greetings ! .. I'm a bit of a newbie when it comes to large PA systems, and the one I just acquired looks like an old (but potentially decent) fixer-upper.
I'm getting a signal on the included EQ, compressor & amps (("Electro-Voice 7600" / 1200w stereo amp) & 2 x "Amcron PSA-2" 600w mono amps).. also came with a custom Crossover XLR 4-in / 4-out (still need to research crossover setups) and I already have a Bryston 2B-LP stereo amp, not tested, but looks fairly new.

My main issue at present, is getting sound from amps to speakers.
The speakers each have 2 x 1/4 jack inputs, labelled "4ohm parallels". Any advice on connecting them ?!

Should I be making something like this ? https://www.youtube.com/watch?v=B0acojlsf5M
Attached Thumbnails
connecting old large speakers to amp (4ohm parallels) 1/4" in only?-20200709_141734.jpg  
Old 6th August 2020
  #2
Gear Maniac
 

Did you not get speaker cables with the gear? If not you just need some with 1/4" connectors, those were commonly used back in the day. Note.. you should not use 1/4" instrument cables as the wire gauge is much too small.

Do you know the model numbers for the speakers?
Old 6th August 2020
  #3
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Thanks for the insight paul o ! . . .

so if I understand correctly, I could connect to the speaker with 1/4 "banana plugs" (1 plug for negative / 1 for positive) using thick speaker wire (at least 12-14 awg) ?

I can't seem to find any additional info on the speaker, other than what's in the pic. the soundsystem fell into my lap a few days ago.. complete with rack & musty basement smell. speakers are huge & heavy (requires 2 people to lift them) i copped 2 of em, still need to pick up the other 2 ! (my sympathies to the neighbours)
Old 6th August 2020
  #4
Gear Maniac
 

Quote:
Originally Posted by Parasomnia View Post
so if I understand correctly, I could connect to the speaker with 1/4 "banana plugs" (1 plug for negative / 1 for positive) using thick speaker wire (at least 12-14 awg) ?
14ga will be fine but no you don't use 2 jacks, positive is connected to the tip and negative to the ring on a single jack. The second receptacle on the jack plate is to connect to another box.

Quote:
Originally Posted by Parasomnia View Post
I can't seem to find any additional info on the speaker,
Post some more pics of the front of the cabinets. The trademark on the jack plate sorta looks like Martin Audio but not quite. Where are you located?
Old 6th August 2020
  #5
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Quote:
Originally Posted by paul o View Post
14ga will be fine but no you don't use 2 jacks, positive is connected to the tip and negative to the ring on a single jack. The second receptacle on the jack plate is to connect to another box.


Post some more pics of the front of the cabinets. The trademark on the jack plate sorta looks like Martin Audio but not quite. Where are you located?
Thanks again Paul O ! Now I know what to get for wiring : D
regarding the 2nd receptacle on the jack plate, is that optional for chaining additional speakers in parallel ? (depending on how I divide signals from crossover box to amps?)

I was just reminded that the cabinet handles are "ALTEC" - I'm away & only have a few pics handy (needs some cleaning!) - but should be with the setup tomorrow, Montreal, parc-X area - grabbing the needed wires on route via Addison. All very exciting, cheers for your assistance !
Attached Thumbnails
connecting old large speakers to amp (4ohm parallels) 1/4" in only?-20200709_141748.jpg   connecting old large speakers to amp (4ohm parallels) 1/4" in only?-20200709_141627.jpg   connecting old large speakers to amp (4ohm parallels) 1/4" in only?-20200709_142910.jpg   connecting old large speakers to amp (4ohm parallels) 1/4" in only?-20200709_141632.jpg   connecting old large speakers to amp (4ohm parallels) 1/4" in only?-20200709_142806.jpg  

Old 6th August 2020
  #6
Gear Maniac
 

Quote:
Originally Posted by Parasomnia View Post
regarding the 2nd receptacle on the jack plate, is that optional for chaining additional speakers in parallel ? (depending on how I divide signals from crossover box to amps?)
Yes correct.

In those pictures is that the front and back of the same boxes? Do you have others? You have enough amplifiers to power a 3 way system and would only need one of them for the boxes I see in the pics.
Old 6th August 2020
  #7
Lives for gear
 

replace jacks with speakons (or pretty much anything else there is): of all formats, the jacks have the least amount of surface to make contact...
Old 6th August 2020
  #8
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Quote:
Originally Posted by paul o View Post
In those pictures is that the front and back of the same boxes? Do you have others? You have enough amplifiers to power a 3 way system and would only need one of them for the boxes I see in the pics.
The rack also came with a dual 15 band EQ (BST process 10)
I plugged an i-pod direct, to test audio signal lights, (ipod to EQ to Compressor to Crossover to Amps) signals seem to light up fine on each device, hitting peak when cranked. but I removed the Crossover from the chain while testing the speakers, until I know how to properly implement it.

There's another 2 speaker cabinets that come with it, (so 4 total) but I still have to pick those up. Haven't seen them yet, but I assume they are the same.
I'll eventually add my 14channel Mackie (1402VLZ) before the EQ.
plus there's that Bryston 2B-LP stereo amp, which I already had kicking around. (good for options, in case I run into any issues with these older included amps..)

if everything works, do you have any idea how loud & large of a space/venue/event these 4 speakers could power ?
Old 6th August 2020
  #9
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Quote:
Originally Posted by deedeeyeah View Post
replace jacks with speakons (or pretty much anything else there is): of all formats, the jacks have the least amount of surface to make contact...
thanks for the tip deedeeyeah ! .. i will look into getting speakONs : )
Old 6th August 2020
  #10
Gear Maniac
 

A classic PA system like this typically consists of at least 3 sections that are separated low, mid, and high frequency, and sometimes it will have 4 or 5 separate bands. The boxes you have shown so far appear to be the lows or low-mids, so hopefully the other boxes are mids and highs. Here is an example of what a full system like this might look like..

Old 7th August 2020
  #11
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woah cool ! .. this could be a dangerous new obsession. heheh!!
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