I do not want to overload the amp

[AnthonyG]

Hey all, Thanks in advance

ok i may be crazy here but normlly when i have purchased an amp it is usually rated per. channel or per. left/right. I recently purchased a PA AMP in which the instruction manual has me going crazy. (it is probably just me)

The Amp has the capability to directly connect 4 speakers without wiring anything in series or parallel. It has "A" channel with one left and one right powered output and a "B" channel with one left and one right powered output. Total of 4 speakers that can be connected. The "A" and "B" can be selected independantly or at the same time.

Basically I have a totalof 4- 8ohm speakers that can handle 130watts max. each.

I have a CD player connected to a EQ with pre-amp and then connected to the PA amp with 2-RCA (phono plugs) for left and right.

below are the amp specs.
product specifications
Input Impedance .................................................................20k Ohms
Continuous Output Power
Stereo at 1 kHz ....................................... 125 Watts x 2 (8 Ohms)
Stereo at 1 kHz ....................................... 175 Watts x 2 (4 Ohms)
Bridged at 20 Hz to 20 kHz .......................... 250 Watts (8 Ohms)
Bridged at 1 kHz ........................................... 350 Watts (8 Ohms)
Total Harmonic Distortion
(@ 70 Watts, 8 Ohms, 1 kHz, with Band Pass Filter)
MIC (Phone Jack) ............................................................... 0.20%
MIC (XLR Jack) ................................................................... 0.20%
CD/AUX .............................................................................. 0.15%
PHONO ............................................................................... 0.20%
Input Sensitivity (at 0.5% THD, 1 kHz)
MIC (Phone Jack) ............................................................1.35 mV
MIC (XLR Jack) ................................................................1.35 mV
CD/AUX ............................................................................500 mV
PHONO .................................................................................3 mV
Signal to Noise Ratio (Input Shorted) with WTD
MIC (Phone Jack) ................................................................65 dB
MIC (XLR Jack) .................................................................... 65 dB
CD/AUX ...............................................................................75 dB
PHONO ................................................................................70 dB
Frequency Response (at 1 Watt, ± 3dB)
MIC (Phone Jack) .................................................40 Hz ~ 20 kHz
MIC (XLR Jack) .....................................................40 Hz ~ 20 kHz
CD/AUX ................................................................20 Hz ~ 30 kHz
PHONO (RIAA 100 Hz/10 kHz) ..........................+13dB ~ – 14dB
Notch Filter Effect
Range ....................................................................300 Hz ~ 3kHz
Depth .................................................................................. –12dB
Noise Level (Input Short) .......................................................0.75mV
Speaker Impedance ............................................. A,B (4 ~16 Ohms)
A+B (8 ~16 Ohms)
Bridge(8 ~16 Ohms)
Power Requirement ..................................................... 120V AC 60Hz
Power Fuse ...............................................................7 Amps/250 volt
Dimensions ................................................5 3/8 x 19 x 14 1/2 inches
(136 x 482 x 367 mm)
Weight ....................................................................... 27 lbs (12.3kgs)
Here is the section about the total ohms. I am not sure if they are stating the total ohms of the speakers connected to the amp (i connect 4 speakers wih resist. of 8ohms each = 32ohms or if they a talking about per. left and right "A" and "B" or what? generally it is per. pair connected as in one left and one right = 16ohms if both are 8ohm speakers.)

Speaker TerminalsConnect two sets of
speakers (Left and
Right, for A and B).
Audio Input Jacks
connecting speakers
You can connect one or more 4-, 8-, or 16-Ohm speakers to
the amplifier. To ensure equal volume from each speaker, all
connected speakers should have the same impedance rating.
Proper phasing is important when you use more than one
speaker in the same room or area. Out-of-phase speakers can
lose up to one-half of their potential volume, and can have a
significantly decreased bass effect .

You can also bridge the amplifier's channels. The amplifier
has two channels: A and B. If you connect two pairs of
speakers, follow these guidelines:

• Speakers connected to the same channel (A or B) are
part of a pair and must be of the same impedance.

• Speakers connected to different channels (A or B) are
not part of a pair and can be different impedance.

determining total speaker impedance
Before you connect speakers to the amplifier, you must
determine the total speaker impedance. To determine total
speaker impedance, you must first decide if you are going
to connect the speakers in series, parallel, or a series/parallel
combination.
If you are connecting more than two speakers in series
only or parallel only, be sure the total impedance does not exceed the amplifi er’s maximum impedance (16 ohms) or fall
below the minimum impedance (4 ohms). You can achieve
a proper total impedance by combining series and parallel
connections.

A total speaker impedance higher than 16 ohms
or lower than 4 ohms can damage your amplifi er
or speakers. When determining the total speaker
impedance, fi rst determine whether you are
connecting the speakers in series, parallel, or a
series/parallel combination.
connecting two speakers in series
Speakers are connected in series when the first speaker’s
positive terminal is connected to the next speaker’s negative
terminal.
Determine the total speaker impedance of speakers
you want to connect in series by adding up
the individual impedances of all the connected
speakers.
For example: If connecting two 4-ohm speakers in
series, your total speaker impedance is 8 ohms.

connecting two speakers in parallel
Speakers are connected in parallel when the speakers’
negative terminals are connected together and all their
positive terminals are connected together.
Determine the total speaker impedance of speakers
you want to connect in parallel by dividing the
impedance of one speaker by the number of
speakers.
For example: If connecting two 8-ohm speakers
in parallel, divide 8 (one speaker’s impedance)
by 2 (number of speakers). Your total speaker
impedance is 4.

unbridged connection
Use this connection if you are connecting more than one
speaker on the same channel or if you do not have highpower
speakers.
1. Connect the speaker wires to the corresponding
left and right positive (+) and negative (–) speaker
terminals.
2. Connect the other end of the left and right speaker's
positive (+) and negative (–) wires to the amplifi er's
corresponding SPEAKER LEFT and SPEAKER RIGHT
terminals for each channel. To connect speaker
wires to the amplifi er, turn the knob on the terminal
counterclockwise until it stops, insert the bare wire
inside the space between the knob and the amplifi er,
then turn the knob clockwise until it stops to secure it.
3. Make sure the STEREO/MONO switch is set to
STEREO.

so finally i am asking if connecting one speaker with 8ohms to each of the four outputs is safe or am i doubling the total rated ohms capibility of the amplifier if i do so.

 

[markw]

Wow, for all that verbiage it fails to tell me one very important thing.

When you run both A and B speakers simultaneously, does the switch connect them in series or parallel?

Theoreticaly, if you have all 8 ohm speakers and you choose to run both channels A and B, if they are connected in series, you will be fine. You'll have a 16 ohm loasd on each channel. But, if they are connected in parallel, you'll have a four ohm load on each channel.

With all those words, maybe I missed something here?

 

[AnthonyG]

MarkW
Thank you for the reply. lol on all the verbiage sorry about that. No where does anything tell me what the "A" and or "B" switch does. from what i read if "A" is selected you will listen to the left and right channels on "A" and if "B" is selected you will listen to the left and right channels on "B". If both are slected "A" and "B" you will listen to both speakers on "A" and oth speakers on "B". I think i am way too wordy for something this simple LMAO.

basically there are 8 screw terminals on the back of the amp.
4 positive and 4 negative
on the front of the amp there is an "A" button and "B" button

normally a no brainer take all 4 seakers and connect one to each pair of screw terminals (+ & -).

my dilema is that the instruction manual starts talking about how you can connect 4, 8, or 16ohm speakers then goes on about the total ohm limit for the amp. usually it is per. pair of speakers connected (one left and one right speaker) which i would think is 16ohms? but since this amp has 2 lefts and 2 rights I would think that is 32ohms?

ok let me try this-here is the link to the instruction manual. the info i am refering to is on pages 16 thru 19.

rsk.imageg.net/graphics/uc/rsk/Support/ProductManuals/3202055_PM_EN.pdf

then tell me how you would connect four speakers (with 8ohms each) to it?

 

[markw]

Look at it this way: you've only got four speaker terminal sets, two columns labeled "right" and left", and two rows "A" and "B", I don't see too much choice here.

My take on this is that one "pair" of speakers would be the A and B speakers on one channel. Each channel appears to be a totally separate entity and the impedances would (should) have no bearing on the other channel.

Using your eight ohm speakers. in series, they total out to sixteen ohms per channel. In parallel, they total out to four ohms per channel. If this is the case, you should be fine in either case.

Why the manual goes into such detail is beyond me. Technically it may be correct, but does not add to yhe user's use of the dang thing.

 

[AnthonyG]

Thanks

After I was overthinking it it way too much, I beleive you are correct. one speaker per. pair of terminals at 8ohms should be fine. I can't imagine that it would cause damage to the amp. If something does happen by chance I will post it up and thank you again.

 

[fmw]

By definition, those outputs are paralleled on a pro audio power amp. If you run a pair of 8 ohm speakers from each pair of outputs, the amp will see 4ohms on each output. Not a problem. The amp is designed for that purpose.