inpedence load ?

[SEAWOLF97]

Not having any problems , just curious.

My mains are 4 ohm and sometimes drop to 2 . B speaker (single passive sub) is 8 ohm. What is the total load when both played together ?

They are both wired to a speaker selector box that has a feature that when selected will always present an 8 ohm load to the amp , but that feature seems to kill bass output.

[sourceoneaudio]

Seawolf,
I believe 4 and 8 parallel = out to a 3.2 ohm load. Also some speaker switchers can reduce output, and over all quality of sound depending on the maker. If you have to have one, Adcom use to make switchers that were considered High Power capable. (e-bay $50.00 to $60.00) Also, yes usually the receiver, or power amp sees the load of the switcher and not the speakers direct, and the better switchers will have an on board protection circuit. Real good quality switchers for up to 6 pairs that do all the above and do not affect sound quality and handle high power can run as much as $500.00 retail.


J/S-S1A

[grumpy]

ain't nearly that simple, but if you're amps not burning up... there you go.

sounds like you -might- be running different frequency bands in parallel...
are you running your mains full-range?
where (in frequency) is the 2 ohm dip?
is your passive sub actually using a passive crossover?
at what frequency?
Does the switcher simply toss in 4ohms in-line when you have both pairs selected?
...

[SEAWOLF97]

ain't nearly that simple, but if you're amps not burning up... there you go.

Its a BGW 250d , doing fine.

sounds like you -might- be running different frequency bands in parallel...

I think so.
are you running your mains full-range?

yes
where (in frequency) is the 2 ohm dip?
unknown
is your passive sub actually using a passive crossover?
at what frequency?

all that is marked is "o/p above 110 hz" . So A and B are doing 110 and below.

Does the switcher simply toss in 4ohms in-line when you have both pairs selected?

unknown

[johnaec]

I believe 4 and 8 parallel = out to a 3.2 ohm load.

Not exactly. The formula for ohms in parallel is (R1xR2)/(R1+R2). That gives you 32/12 in this case, or 2.67 ohms.

John

[edgewound]

Not having any problems , just curious.

My mains are 4 ohm and sometimes drop to 2 . B speaker (single passive sub) is 8 ohm. What is the total load when both played together ?

They are both wired to a speaker selector box that has a feature that when selected will always present an 8 ohm load to the amp , but that feature seems to kill bass output.

4 ohms and 8 ohms nominal in parallel = 2.6 ohms nominal.

When you set your impedance compensation switch on the selector for a constant 8 ohms, you lose most of the amp's power to resistors.

That leaves about 10% or so of available amp power to drive your speakers.

Does that explain why you're losing bass output?

Passive resistive speaker selectors are best when either using 1 pair of speakers at a time; your amp can almost deliver full power into 1 ohm or less running multiple speakers at once (good luck with that)...;or the best use for it is: In-wall/ceiling speakers for multiroom distributed sound at low/moderate levels in your home/office with impedance compensation switched on to protect the amp.

[SEAWOLF97]

4 ohms and 8 ohms nominal in parallel = 2.6 ohms nominal..

does it matter in the equasion that there are two 4 ohm speakers and one 8 ohm ?

[grumpy]

does it matter in the equasion that there are two 4 ohm speakers and one 8 ohm ?

for half the amp, yeah. Each side should be treated independently.
dual voice coil on the sub? BTW, at your 2ohm dip, this is going to be rather
amp-unfriendly, especially if it's below your passive 110Hz crossover. -grumpy

[SEAWOLF97]

for half the amp, yeah. Each side should be treated independently.
dual voice coil on the sub?

YES

yes

[grumpy]

Then, I -assume- you're running the DVC's in series to get your 8ohms that you're running
from one channel of the amp? I really think you'd be better off with a separate amp for your
sub, if that's tolerable. Then you can run each coil from it's own L/R side amp and let
the sub do the summing to mono. .. my $.02 -grumpy

[SEAWOLF97]

OH , this is too funny !!!

the sub had an occasional rattle....

I just opened it up to see if anything was loose. To my complete surprise, there were about 30 garlic cloves in there !!!

At least I know it wasn't owned by a vampire !

(the CV LH is a very nice cast basket, rest is kinda cheap)

[SEAWOLF97]

Then, I -assume- you're running the DVC's in series to get your 8ohms that you're running
from one channel of the amp? I really think you'd be better off with a separate amp for your
sub, if that's tolerable. Then you can run each coil from it's own L/R side amp and let
the sub do the summing to mono. .. my $.02 -grumpy

yes, running 2 seperate speaker leads to the sub, using L & R channels
extra amp may be out of the question, running out of rack space.

[sourceoneaudio]

4 ohms and 8 ohms nominal in parallel = 2.6 ohms nominal.
The best use for it is: In-wall/ceiling speakers for multi room distributed sound at low/moderate levels in your home/office with impedance compensation switched on to protect the amp.

I knew I was close. I also agree with the above statement. I use my switcher for multi room use now and that is all I would ever use it for. Never in a main room system, for power loss and fidelity reasons. Time to buy more power if your out of places to plug stuff into.


J/S-S1A

[grumpy]

Hmm... 8ohms per voice coil? I suppose, since this unit was intended for home use.
In that case, then the above is mostly true, and for both channels.

My wild-ass guess is that your 2ohm dip doesn't overlap the sub range and with that
big BGW amp, you're ok, if not optimal, for home use (I haven't heard that you're blowing
any amp fuses )... I wouldn't do this with a "vintage" Marantz receiver.
Do you have a way to adjust/match sub/full-range levels? -grumpy

[Zilch]

Nobody's raised the phase issue, either.

So I am....