LSiM 707 bi-amp question

mpitogo

LSiM 707 bi-amp question.

I am assuming the bonding wire couples the mid-woofer, mid-driver and tweeter (basically 703 top half) from the two oval subwoofers correct? If so I'm looking to setup an active crossover for the subs and the top half set at 100Hz. Do I have to remove the passive crossovers? Is 100Hz appropriate? I'm trying to prevent too much roll off in the crossover region but also trying to prevent wasted energy from going to where they shouldn't.

I am breaking in a new pair of 707 and was playing different test tones, 20Hz and 30Hz at 10-80 watts and surprisingly the mid-woofer and mid-driver was trying to rattle of those frequencies?!? I felt active driver movement as I varied the volume. That can't be good?
Shouldn't the HPF even a passive crossover prevent those frequencies from reaching the smaller drivers?

mrbigbluelight

Almost gave the wrong advice. Rechecking my info.

mpitogo

i also did not see a wiring guide in the other section. short of opening it up, someone must know..?

K_M

From manual.....

"the upper set of binding posts are for the high frequency drivers"

It does not specify, if it is only the tweeter, but the older Lsi series, the binding posts (upper) were just the tweeter, and the lower were the other drivers.

K_M

Bi-Wiring (see Figure 1)
Bi-wiring can provide noticeable improvements in the overall
transparency of your loudspeakers. Run separate speaker wires
to the low and high frequency drivers from a single amplifier
(the upper set of binding posts are for the high frequency drivers,
the lower set of binding posts are for the low frequency drivers):
after removing the jumpers, connect one set of speaker wires
to the upper terminals on each speaker and one set of wires
to the lower terminals. Connect the other ends of both wire
sets to the same amplifier outputs.
Bi-Amping (see Figure 2)
Bi-amping allows you to use separate amplifiers for the high and
low frequency sections of your loudspeaker for greater dynamic
range and lower distortion. We recommend that your separate
amplifiers have identical gain to preserve the speaker’s voicing
balance. After removing the jumpers, connect the speaker wires
from the high frequency amplifier outputs to the upper set of
terminal posts on each speaker. Follow the same procedure
for connecting the low frequency amplifier outputs to the
lower set of terminals. Remember to maintain correct wiring
polarity (+ to +, – to –) in all connections.

[Deleted User]

Hello,
The lower set of binding posts connect to the lower three bass components, the two woofers and the 6.5" mid-bass driver. The upper set of binding posts connect to the tweeter and mid-range components. I wouldn't recommend removing any of the internal crossover components.
Cheers, Ken

mpitogo

really? what is the x/over point between the 6.5 and the 3" mid. I would have thought it could be a 703 split. I was looking to run a higher power amp for the two 6x9 with an active x-over at around 100hz and room correction such as the miniDSP 2x4HD.

afterburnt

I am waiting with baited breath to see what you find. I like mine for HT but I have chosen a different tac with music.

F1nut

mpitogo

Well duh, just uncouple them... the 3" mid and tweeter are as @KennethSwauger pointed out connected to the upper binding posts. I'll have to figure out the rest.

Viking64

SoundForce wrote: »

Ive been building speakers for over 0 years and never seen such stupidity.

LOLWUT????

txcoastal1

SoundForce wrote: »

OH BTW... Take a real good look at that pic of the speaker cutout which allows you to see inside of it... I can tell you it isnt exactly like that... That stuffing is NOT that way at all.. What they did is take some very thick sheets of polyfill and wedged them in there and glued one end to make them stick so they would not slide out... After doing speaker work for 3 decades i know having polyfill in small enclosures aint a good idea cause it takes of what little air space is available and causes problems.. SO I took a few coat hangers and a hand portable drill and stuck the hanger in the port on the rear and eventually was able to pull that stuff out.. It was super super difficult. They is no way to get that out unless you go through the port. The other 2 chambers is basic, remove the screws for the speakers and remove the poly fill. The upper poly for the midrange and midbas is just a small sheet cut in almost half. Its nothing like the pics. What I pulled out was aleast, at least a good hald or almost half of the speakers air space volume.. That aint good..And this stuff is thick.. Its not fluffy like the pics at all. Its almost exactly like a cheap sheet of AC filter you see in your house AC. Stiff and takes up way too much air space.. you would think they made it this way.. NO.. the difference in bass clarity is apparent.. Drops lower and cleaner now.

What are your favorite speakers?

F1nut

Maybe in another 3 decades you'll have learned why poly fill is used.

WLDock

SoundForce wrote: »

I realized the midbass and subs is tied in to each other when i had the sub woofer active and sending them just bass and the sound was so off i couldnt figure out why till I said... ohhhhh Now I know. and smh... There really is no biamping these

SoundForce wrote: »

I found this out becuase , liek most of us, we wanted to actually bi amp the speakers and possibly use active crossovers on tme. NOPE

If using two level matched identical amps in a Passive biamp mode, I don't see where there would be a problem with levels as POLK has already design that in the passive. How would this be different from the same filters powered by a single amp? The LOW amp has to be level matched so that is does not over power the HIGH amp.

Further, if one wants to 'truly' go active on these 4-way speakers and finds the crossover a limiting factor then one has to asks if they 'truly' want to go there. To 'truly' go there would take more of a DIY spirit, even if the midbass was tied to the Mid/Tweet.

However, lets look at all options.

1) Passive Bi-Amp as is.

2) Passive Bi-Amp with the Midbass connected to the High Terminal. Either purchase two additional low freq crossover from Polk or build your own. Remove the Midbass from the Low crossover #1 and connect to the added Low crossover #2. Then, connect the Low crossover #2 to the High Terminal. Now the midbass/Mid/Tweet are on the High Terminal and just the Woofers are on the Low Terminals

3) Active/Passive Tri-Amp. Remove the Woofers, Midbass from the passive and drive off individual amps #1 & #2 and DSP. Keep the Mid/Tweet tied to the passive and power with individual amp #3.

4) ALL OUT 4-WAY ACTIVE! Bypass all passive crossovers, 8 channels of amplification, DSP, room correction of choice.

Much is possible if one is willing and able to walk it like they talk it. Just look at these LSiM crossover mods:

https://forum.polkaudio.com/discussion/155256/polk-audio-lsim703-crossover-modification-thread/p1

https://forum.polkaudio.com/discussion/165092/external-lsim703-crossover-modification

F1nut

You're wasting your time.

Viking64

F1nut wrote: »

You're wasting your time.

I've spent over 0 years of my life wasting my time.

F1nut

I see Google is your friend.

F1nut

SoundForce wrote: »

Everybody wants to be a comedian cause my number 3 button sometimes is dead on this keyboard... LOL
Whatever.. Look dudes. seriously.. The whole entire point of bi amping is to have the uppper sounds on one amp and lower bass on another amp so the sound doesnt get restrained when huge bass notes hit. Problem is, with these, you cant do that. They messed up. Sure you coudl add 2 amps but that really defeats the purpose of byamping.. They could have adding all speakers but the tweeer to the sub wiring and would youc all that biamping? SMH seriously .. Lets get realistic..

Now Id liek to get the 703 crossovers and use them in the 705 so I can do a proper biamping job... Anyone want to offer me there old 703 crossovers send me a pm.. Im sure we can work something out..
I asked Polk 2 times for the schematics and they say.. NO...
Its like asking for the service manaul of your car when you want to change the fuses and they tell you no its still under warranty.. Thats what polk did...
Not good polk.. not good at all..

If you had any idea of what you're talking about you would not need schematics. I could pick apart many of your other comments, but you made my point with that one alone. I have to say you come off as nothing more than a troll.

WLDock

SoundForce wrote: »

The whole entire point of bi amping is to have the uppper sounds on one amp and lower bass on another amp so the sound doesn't get restrained when huge bass notes hit. Problem is, with these, you cant do that. They messed up.

If you remove the jumper the HIGH is 280Hz-UP (~6 Octaves) and the LOW terminal is 280Hz-DOWN (~4 Octaves). Yes, its get a little tricky with a 4-way and we don't know the driver characteristics and sensitivity. Who knows if 100Hz-UP makes sense? For sure with just the MID/Tweet together there will be no major upper bass fundamentals to restrain the sound as you state.

Further, consider a slamming song like PONY by Ginuwine. Look at the major peak at 50Hz. Yet there is still a ton of mid-bass -lower midrange slam above 100Hz. Now a bad thing to have 280Hz down covered by one amp and the upper by another playing content with heavy upper bass.

SoundForce wrote: »

Not good polk.. not good at all..

Its up to the design team to decide whats makes sense. Consider the well received Ascend Acoustics Sierra Tower. It does not even have bi-wire/amp terminals because the designer feels that passive bi-amping offers no advantage.


Then there are others that give you terminals for each driver!


There are millions of speakers out there that differ in any many ways. Either modify what you have or find a set that works for you.

BlueFox

Interestingly, Magico only provides one set of speaker terminals. Apparently, they feel biamping is not useful with their speakers.

WLDock

F1nut wrote: »

You're wasting your time.

Just trying to help and be a voice of reason were I can.

gp4jesus

I want to I be wrong, but I believe no two drivers produce the same FR. I believe it’s a 4.5 way system.

Obviously the 3 upper driver FRs are different. I think this loudspeaker’s lower woofer is LP’d an octave below the mid’s HP F3. I think someone touched on it but just in case: anticipate minimum quad amp.

Study the cut-away closure. The woofers are loaded or aligned differently. Also the distance of the bottom woofer from the mid is another indicator.

Plan to buy a lot of amps, a different pair of speakers, or anti-depressants. I wish you good fortune and sanity following whatever you decide. 😊 Tony

msg

.

txcoastal1

BlueFox wrote: »

Interestingly, Magico only provides one set of speaker terminals. Apparently, they feel biamping is not useful with their speakers.

Same with my Dynaudio C4’s

tonyb

I'm wondering what he thinks bi-amping is going to accomplish, or what it's going to cure for him. Sure hope it's not loudness he seeks. Maybe he should state what he doesn't like about the sound, the gear used , and we could have helped him. He obviously has his mind set on bi-amping to cure some sort of perceived faults in the sound.

pitdogg2

haasni123 reported

joecoulson

pitdogg2 reported

pitdogg2

Great....

joecoulson

Lol!!

gp4jesus

@mpitogo I hafta ask what others brought up: what are you “trying to fix?” Otherwise a clean, robust 250+ should take of business quite handily. But having bi, tri, and quad amped experience...

Gonna stir the pot

WLDock wrote: »

If you remove the jumper the HIGH is 280Hz-UP (~6 Octaves) and the LOW terminal is 280Hz-DOWN (~4 Octaves).

Yeah and?

WLDock wrote: »

Yes, its get a little tricky with a 4-way and we don't know the driver characteristics and sensitivity.

Nailed it!

WLDock wrote: »

Who knows if 100Hz-UP makes sense?

probably not

WLDock wrote: »

For sure with just the MID/Tweet together there will be no major upper bass fundamentals to restrain the sound as you state

yup

WLDock wrote: »

Look at the major peak at 50Hz. Yet there is still a ton of mid-bass -lower midrange slam above 100Hz.

So?

WLDock wrote: »

Now a bad thing to have 280Hz* down covered by one amp and [280hz on up]per by another playing content with heavy upper bass.

I don’t see the “280hz problem*” you see or rather understand why that’s a bad thing.

The passive XO circuitry has no way of knowing:
a. 1 amp or two
b. Vertical or horizontal passive bi-amp

Chances are great two amps of the same make and model would handle that “Pony” passage better than a single, especially if the impedance* drops below 4 ohms or a large portion of the “curve*” below ~300hz stays under 6ohms.

My 2 cents

Tony