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 :D

[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 :D

[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 :D)... 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.... :p

[edgewound]

Nobody's raised the phase issue, either.

So I am.... :p

I don't think that's the issue here.

He said bass goes away when impedance compensation is switched on.

More than likely a power sucking issue...and then the combination of 8 ohm dual voice coil sub draws less current than his 4 ohm OHM F's. Ohm's law is taking over.

[hjames]

Nobody's raised the phase issue, either.
So I am.... :p

Well thank god SOMEBODY's not afraid to lose phase!:applaud:

[SEAWOLF97]

I don't think that's the issue here.

He said bass goes away when impedance compensation is switched on.

More than likely a power sucking issue...and then the combination of 8 ohm dual voice coil sub draws less current than his 4 ohm OHM F's. Ohm's law is taking over.

that happened with only the F's running solo, also.

why phasing problem ? I always watch polarity.

[edgewound]

that happened with only the F's running solo, also.

why phasing problem ? I always watch polarity.


Ok...last response on this, then I'm out.

Your Ohm F's are 4 ohms, right?

You turn on impedance compensation switch on speaker selector to give CONSTANT 8 OHM RESISTIVE load, right?...which is probably killing amp's damping factor, also.

Viola'...8 ohms draws less current than 4 ohms= less power to drive the speakers.

In effect...the amp is driving the speaker selector and not the speakers when the impedance compensation switch is engaged.

[SEAWOLF97]

In effect...the amp is driving the speaker selector and not the speakers when the impedance compensation switch is engaged.

seems like good answer , thanx

[SEAWOLF97]

OKAY ....believe it or not I do listen to you guys.

The Yam C-4 has 2 pre outs. So to get rid of the speaker box, I pulled everything out of the box and put it aside. Wired only the 4 ohm OHMs to the BGW amp.

Found a Pioneer SA-5500 that I didnt realize was mine and ran the pre2 to it and then wired the SUB and the 4412s to the Pioneer. That, as a by product gave me volume control over the sub, which may be superflous now that the 4412s are playing, and both amps are controlled by the single pre amp.

confusing ?

[grumpy]

confusing ?

Nope :). Just wondering if you tried this configuration without the 4412A's
(not being familiar with the Pioneer ... A/B speaker control on it?)
and are you happy with how it sounds?

-grumpy

[SEAWOLF97]

Nope :). Just wondering if you tried this configuration without the 4412A's
(not being familiar with the Pioneer ... A/B speaker control on it?)
and are you happy with how it sounds?

-grumpy

still dinging around, happy with results, so far.. the pioneer is an integrated amp with a/b control. So now only the OHMs on main amp. No speaker selector box and sub and 4412s on second amp, all controlled by Yam pre.

who knows ? maybe different next week.

[SEAWOLF97]

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

so if you are running a and b sets of 8 ohm speakers.....8x8(64) / 8+8 (16) so your overall impedance is 4 ?

I see many people running 2 sets like this on very normal receivers, so many (most ?) receivers are OKAY with a 4 ohm load ?

one more question : how does impedance relate to efficiency ? (or does it ??)

[grumpy]

so if you are running a and b sets of 8 ohm speakers.....8x8(64) / 8+8 (16) so your overall impedance is 4 ?

I see many people running 2 sets like this on very normal receivers, so many (most ?) receivers are OKAY with a 4 ohm load ?

one more question : how does impedance relate to efficiency ? (or does it ??)

If they were 8 ohm resistors, it would be fairly honest to just say yes.
... and at moderate levels, most quality receivers should be able to handle
it... Reading-TFM is always a good idea though. I'm gonna leave that last
question for someone else. -grumpy

[SEAWOLF97]

Reading-TFM is always a good idea though. -grumpy

I'm big on RTFM, on everything I buy. But on vintage gear, most times TFM is MIA. So hopefully your friends can sometimes fill in.

Thanx for some of the answers , Grumpy. What part of SoCal you in ?

[edgewound]

... Reading-TFM is always a good idea though. grumpy
:rotfl: :thmbsup: :applaud:

[edgewound]

I'm big on RTFM, on everything I buy. But on vintage gear, most times TFM is MIA. So hopefully your friends can sometimes fill in.

That's true.:)


Thanx for some of the answers , Grumpy. What part of SoCal you in ?

He's pretty close to me.

He won't ever admit it....but grumpy has skills most of us will never know.
Go back and look at some of his interpolation/extrapolation on Everest II.

Hit a screaming line-drive every time.

[SEAWOLF97]

He's pretty close to me.

I just ask as I grew up in Granada Hills (SF valley) , HS and college in Santa Barbara , Navy time was San Diego and Monterey. Back when most everyone in SoCal had orange trees in their yards.

[edgewound]

I just ask as I grew up in Granada Hills (SF valley) , HS and college in Santa Barbara , Navy time was San Diego and Monterey. Back when most everyone in SoCal had orange trees in their yards.


Yep....Unfortunately, the smell of orange blossoms is a distant happy memory.

My dad told me when he drove in to California, top-down in the late 1940's, the orange blossoms were just heavenly.

[grumpy]

Still have citrus in the back yard & grew up with orange trees
at our's and all of the neighbor's houses
(tract houses overlaid the orchards a bit east of Los Angeles...many
of the trees stayed and some are still there, blossoms & all... one of
the pleasures in visiting my folks).

I still can't really enjoy anything but fresh squeezed :D

-grumpy

[Zilch]

You're playin' the 4412s in a different room, right?

http://www.jblpro.com/pub/technote/fat_wht.pdf

Also, 4412s are negative polarity. I don't know what Ohms are.

http://www.jblpro.com/tech-library/JBL_TechNoteN1V12C_v5.pdf

[SEAWOLF97]

Also, 4412s are negative polarity. I don't know what Ohms are.

http://www.jblpro.com/tech-library/JBL_TechNoteN1V12C_v5.pdf

OKAY, I read that. Does it mean that the 4412's s/b wired RED on amp to BLACK on speaker and vv ? If so, I wud think that most of the following in the wild are wired WRONG. I have no book or tech nfo on the OHM's , so assuming positive.


All 4300-Series models (except models 4311
and 4312L, R) are negative
The following models are negative:
4406 4408L, R
4410L, R 4412L, R
4425L, R 4430L, R
4435L, R


The firm decision was
made that no “legacy” transducers in existence at
that time would be changed during their remaining
catalog lifetime. In most cases, JBL loudspeaker
systems, even if they make use of negative polarity
transducers, have been internally wired so that they
“behave” as positive systems. That is, a positive signal
at the red or positive terminal of the system will
cause the low frequency cone to move outward.

[Zilch]

There is no right or wrong, unless you're using them with other speakers which may be opposite polarity in like a home theater setup.

Running multiple pairs in the same listening space with the same program material is wrong, tho, if you're doing that, for the reasons cited in the first reference.

Receivers are multi-pair capable for local and remote speakers. In the olden days, we typically had only one receiver, and extra speakers in another room.

Check your Ohms with a 1.5V battery. The cone moving up would be equivalent to the JBLs moving out. 4412s will move in when + is applied to the red terminal, presumably.

Be aware that people usually (sometimes, often, typically?) ignore me about this stuff -- they don't want to hear it.... :p

[SEAWOLF97]

There is no right or wrong, unless you're using them with other speakers which may be opposite polarity in like a home theater setup.


thats a relief. Was afraid that if wired wrong, the music wud play backwards..:o:



Be aware that people usually (sometimes, often, typically?) ignore me about this stuff -- they don't want to hear it.... :p

IMHO , forum readers do NOT ignore you very much. Have NEVER seen you put out "less than accurate" info.

[4313B]

Be aware that people usually (sometimes, often, typically?) ignore me about this stuff -- they don't want to hear it.... :pYeah, yeah, we know all about why you get ignored. :p And you are right in that oftentimes people shut down if they aren't hearing what they want to hear.
IMHO , forum readers do NOT ignore you very much. Have NEVER seen you put out "less than accurate" info.Well... anyway... He has put a ton of effort into what it is he does and he has stuck with it long after most people would have moved on.

[Ian Mackenzie]

A schematic of the passive sub woofer and the switcher would probably explain a lot. :coolness:

As I recall the Control 1 sub puppy worked along similar lines.

As a matter of related interest Harman has a nice series of white papers on their corportate web covering setting up of loudspeakers including subs in your home. Its worth a read as there is so much misinformation on the subject.