W

WJGJ

Enthusiast
My preamplifier has 2 sets of outputs rated at 600 ohms.

These 2 sets of output are currently driving 2 power amplifiers, which have 100,000 ohms input each (4 interconnects).

The amplifiers are vertically bi-amped into 1 pair of speakers.

I would like to add a subwoofer by using 2 Vampire splitters, inserted into the preamp outputs which are driving the speakers bi-amped mid-range/bass speakers.

The subwoofer amplifier has an input impedance of 15,000 ohms.

According to what I have read, 600 ohms to 115,000 ohms should be acceptable. I just want to be sure before I buy the subwoofer.

Thank you very much for your help.
 
slipperybidness

slipperybidness

Audioholic Spartan
My preamplifier has 2 sets of outputs rated at 600 ohms.

These 2 sets of output are currently driving 2 power amplifiers, which have 100,000 ohms input each (4 interconnects).

The amplifiers are vertically bi-amped into 1 pair of speakers.

I would like to add a subwoofer by using 2 Vampire splitters, inserted into the preamp outputs which are driving the speakers bi-amped mid-range/bass speakers.

The subwoofer amplifier has an input impedance of 15,000 ohms.

According to what I have read, 600 ohms to 115,000 ohms should be acceptable. I just want to be sure before I buy the subwoofer.

Thank you very much for your help.
The first real item--Why the heck do you have/want such a complicated setup? That is never ideal and invites problems or mistakes in your system.

Next item, when you add 2 amps in PARALLEL, the load seen by the source will NOT add to 115,000ohms! Rather, the total ohms must go down (more difficult load to drive), lower than either of the loads by itself. A simple thought process will make this clear--the electricity now has 2 paths for flow. You need to review the calculation for adding loads (resistors) in PARALLEL, you used the calculation for SERIES loads.

In your case, the input impedance would now be 13,000ohms if you connect both the sub and the amp to the same pre-amp output.
 
slipperybidness

slipperybidness

Audioholic Spartan
My preamplifier has 2 sets of outputs rated at 600 ohms.

These 2 sets of output are currently driving 2 power amplifiers, which have 100,000 ohms input each (4 interconnects).

The amplifiers are vertically bi-amped into 1 pair of speakers.

I would like to add a subwoofer by using 2 Vampire splitters, inserted into the preamp outputs which are driving the speakers bi-amped mid-range/bass speakers.

The subwoofer amplifier has an input impedance of 15,000 ohms.

According to what I have read, 600 ohms to 115,000 ohms should be acceptable. I just want to be sure before I buy the subwoofer.

Thank you very much for your help.
From the limited info that you have provided.....I would suggest feeding the sub off one of the pre-amp outs, and splitting the other pre-amp out to feed both amps.
 
W

WJGJ

Enthusiast
The first real item--Why the heck do you have/want such a complicated setup? That is never ideal and invites problems or mistakes in your system.

Next item, when you add 2 amps in PARALLEL, the load seen by the source will NOT add to 115,000ohms! Rather, the total ohms must go down (more difficult load to drive), lower than either of the loads by itself. A simple thought process will make this clear--the electricity now has 2 paths for flow. You need to review the calculation for adding loads (resistors) in PARALLEL, you used the calculation for SERIES loads.

In your case, the input impedance would now be 13,000ohms if you connect both the sub and the amp to the same pre-amp output.
Thanks for your insight. According to Paul McGowan of PS Audio (which can be viewed on YouTube), the input impedance of the amplifiers you're driving should be within 10~20 times of the output impedance. So, 13,000 ohms divided by 600 ohms would be 21.66. Therefore I should be okay. How did you figure 13,000 ohms? Thanks
 
W

WJGJ

Enthusiast
From the limited info that you have provided.....I would suggest feeding the sub off one of the pre-amp outs, and splitting the other pre-amp out to feed both amps.
I appreciate your saying it's a parallel load, not a series load. I just found a website that calculates 3 resistors, 100,000 + 100,000 + 15,000, and the result is 11538.46 ohms. 11538.46 divided by 600 is 19.23. That should be okay. Thanks.
 
W

WJGJ

Enthusiast
From the limited info that you have provided.....I would suggest feeding the sub off one of the pre-amp outs, and splitting the other pre-amp out to feed both amps.
Also, I appreciate your advice to use 1 set of 600 ohm outputs to drive the amplifiers (split), and 1 set of outputs to drive the subwoofer. It appears to work out better mathematically. According to the manufacturer of the preamplifier, the output at all 4 outputs is 600 ohms. Thanks slipperybidness.
 
Pogre

Pogre

Audioholic Warlord
Thanks for your insight. According to Paul McGowan of PS Audio (which can be viewed on YouTube), the input impedance of the amplifiers you're driving should be within 10~20 times of the output impedance. So, 13,000 ohms divided by 600 ohms would be 21.66. Therefore I should be okay. How did you figure 13,000 ohms? Thanks
Well there's part of your problem right there. Listening to Paul McGowan. That guy likes to peddle a lot of snake oil.
 
Kingnoob

Kingnoob

Audioholic Chief
My preamplifier has 2 sets of outputs rated at 600 ohms.

These 2 sets of output are currently driving 2 power amplifiers, which have 100,000 ohms input each (4 interconnects).

The amplifiers are vertically bi-amped into 1 pair of speakers.

I would like to add a subwoofer by using 2 Vampire splitters, inserted into the preamp outputs which are driving the speakers bi-amped mid-range/bass speakers.

The subwoofer amplifier has an input impedance of 15,000 ohms.

According to what I have read, 600 ohms to 115,000 ohms should be acceptable. I just want to be sure before I buy the subwoofer.

Thank you very much for your help.
Are you running a movie theater any pictures what in world ??


Sent from my iPhone using Tapatalk
 
W

WJGJ

Enthusiast
Are you running a movie theater any pictures what in world ??


Sent from my iPhone using Tapatalk
Thanks for your reply. I'm going to purchase a SVS PB-1000 Subwoofer and use the high level speaker connections. No worries now.
 

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