Does anybody remember the post about the JBL 1200.1 amp on how its hooked up a little different to make sure u get the full wattage? I tried to do a search to find it but its way back, it was like when the site came back up. Thanks
Replies (11)
Swez on 10/25/2003 23:24:31
There are several options for hooking up the JBL power series amps.
To get the most out of an RCA hookup, best to use all 4 inputs to amp.
This amp can combine all 4 channel inputs (non-faded) to a single MONO channel output. You can also use 2 channel sub outs from the HU, use a splitter to get 4 inputs and that will work as well.
Main thing here... know the HU output voltage going to amp via RCA's so you can set the gain control to the proper voltage. (to get max RMS power from amp.
This amp can take 250Mv to 4.0 volts and still reach max output to subs.
Does this clarify what you wanted to know?
Swez
ryan on 10/25/2003 23:35:46
No because how could there be 4 channel inputs if its already a mono amp? But i think i understand what ur saying.
Swez on 10/25/2003 23:52:58
You have 4 possible inputs (FR/FL/RR/LR) to feed the preamp section of the amp. Each channel has a bass signal and will be combined into 1 single input for the amp to amplify. (summing of all 4 channels)
More like channel 1+2+3+4 signals = all bass on each channel will be fed to main amplifier circuit. This is how you get maximum input signal to the output section of the amp.
Are we on the same page yet?
Swez
ryan on 10/26/2003 00:05:22
yea i got it, thanks for clearin that up
ryan on 11/4/2003 22:43:36
Swez on this amp it has 4 speaker terminals 2 + and 2-. This is so i can hook up 2 subwoofers even tho its a mono amp. well im using both and its putting out more bass. But the ? is i have all 4 hooked up to one voicecoil should i have 1 set go to 1 voice coil and the other set go to the other or just leave it as i have it now? Hope i made this clear.
compvr15s on 11/5/2003 08:39:07
i think on those mono amps, that you can hook up to just one speaker terminal and get the same power. it only reconizes one load. im pretty sure thats how they work, and then if you hook up another sub to the other side then it will split the power between the loads. good luck
Swez on 11/5/2003 10:26:30
This amp has 2 output terminal sets for ease of wiring multiple subs. The terminals are wired in parallel (to each other) inside the amp.
You can either wire the sub(s) to proper ohms inside the box and connect to amp or if you have dual boxes, one box to each terminal post.
The power the amp puts out to all terminals is the same, based on the total net ohmic load of the speakers wired to the amp.
Swez
ryan on 11/5/2003 18:07:26
Also for the 4 inputs i have FMOD's on the rear if i hook up the front inputs (non-fading) will i need to put FMOD's on them or not. And again thanks for all ur helps guys.
Swez on 11/6/2003 05:28:34
The FMods are needed only when you go ported. If you have a pair of them now, try using only 1 pair of amp inputs with the FMods installed and see how this sounds to you. If it is clean bass and has all the power you need... good enough.
You may need to adjust the amp input gain a bit if over all bass output drops. What is you amp gain settings now as wired? Also, can you get an A/C voltmeter and measure the output voltage at the subs?
Do this measurment now and after removing the non-FMod inputs. If you see a drop in voltage, adjust your gain slightly away from 4.0 Volt settings, until you get the same voltage readings as with all 4 inputs connected. Do you understand these suggestions?
Let us know your findings OK?
Swez
PS Test tone CD is the right tool here when testing the voltage to your subs. Need a constant, calibrated tone to get accurate readings on voltage. Can use "pink noise" tones or fixed bass tones between 40-80 Hz.
ryan on 11/16/2003 15:43:50
Swez i do have a multimeter but where do i put the test leads on to test the output voltage at the sub?
Swez on 11/16/2003 19:38:25
This link will spell it all out for you. The hardest part,is obtaining a dummy load capable of dissapating the amps power abilities.
The O-scope and tone generator help to determine when clipping of the amp is starting to happen. But the non-inductive dummy load will be hard to find. You'll need one of the following:
1. 600 watts, 4 ohm load
2. 1200 watts, 2 ohm load
See this: http://www.eatel.net/~amptech/elecdisc/measpwr.htm
Swez
Replies (11)
Swez on 10/25/2003 23:24:31
There are several options for hooking up the JBL power series amps.
To get the most out of an RCA hookup, best to use all 4 inputs to amp.
This amp can combine all 4 channel inputs (non-faded) to a single MONO channel output. You can also use 2 channel sub outs from the HU, use a splitter to get 4 inputs and that will work as well.
Main thing here... know the HU output voltage going to amp via RCA's so you can set the gain control to the proper voltage. (to get max RMS power from amp.
This amp can take 250Mv to 4.0 volts and still reach max output to subs.
Does this clarify what you wanted to know?
Swez
ryan on 10/25/2003 23:35:46
No because how could there be 4 channel inputs if its already a mono amp? But i think i understand what ur saying.
Swez on 10/25/2003 23:52:58
You have 4 possible inputs (FR/FL/RR/LR) to feed the preamp section of the amp. Each channel has a bass signal and will be combined into 1 single input for the amp to amplify. (summing of all 4 channels)
More like channel 1+2+3+4 signals = all bass on each channel will be fed to main amplifier circuit. This is how you get maximum input signal to the output section of the amp.
Are we on the same page yet?
Swez
ryan on 10/26/2003 00:05:22
yea i got it, thanks for clearin that up
ryan on 11/4/2003 22:43:36
Swez on this amp it has 4 speaker terminals 2 + and 2-. This is so i can hook up 2 subwoofers even tho its a mono amp. well im using both and its putting out more bass. But the ? is i have all 4 hooked up to one voicecoil should i have 1 set go to 1 voice coil and the other set go to the other or just leave it as i have it now? Hope i made this clear.
compvr15s on 11/5/2003 08:39:07
i think on those mono amps, that you can hook up to just one speaker terminal and get the same power. it only reconizes one load. im pretty sure thats how they work, and then if you hook up another sub to the other side then it will split the power between the loads. good luck
Swez on 11/5/2003 10:26:30
This amp has 2 output terminal sets for ease of wiring multiple subs. The terminals are wired in parallel (to each other) inside the amp.
You can either wire the sub(s) to proper ohms inside the box and connect to amp or if you have dual boxes, one box to each terminal post.
The power the amp puts out to all terminals is the same, based on the total net ohmic load of the speakers wired to the amp.
Swez
ryan on 11/5/2003 18:07:26
Also for the 4 inputs i have FMOD's on the rear if i hook up the front inputs (non-fading) will i need to put FMOD's on them or not. And again thanks for all ur helps guys.
Swez on 11/6/2003 05:28:34
The FMods are needed only when you go ported. If you have a pair of them now, try using only 1 pair of amp inputs with the FMods installed and see how this sounds to you. If it is clean bass and has all the power you need... good enough.
You may need to adjust the amp input gain a bit if over all bass output drops. What is you amp gain settings now as wired? Also, can you get an A/C voltmeter and measure the output voltage at the subs?
Do this measurment now and after removing the non-FMod inputs. If you see a drop in voltage, adjust your gain slightly away from 4.0 Volt settings, until you get the same voltage readings as with all 4 inputs connected. Do you understand these suggestions?
Let us know your findings OK?
Swez
PS Test tone CD is the right tool here when testing the voltage to your subs. Need a constant, calibrated tone to get accurate readings on voltage. Can use "pink noise" tones or fixed bass tones between 40-80 Hz.
ryan on 11/16/2003 15:43:50
Swez i do have a multimeter but where do i put the test leads on to test the output voltage at the sub?
Swez on 11/16/2003 19:38:25
This link will spell it all out for you. The hardest part,is obtaining a dummy load capable of dissapating the amps power abilities.
The O-scope and tone generator help to determine when clipping of the amp is starting to happen. But the non-inductive dummy load will be hard to find. You'll need one of the following:
1. 600 watts, 4 ohm load
2. 1200 watts, 2 ohm load
See this: http://www.eatel.net/~amptech/elecdisc/measpwr.htm
Swez
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