Wiring two dual 4 Ohm Voice Coil Woofers to get 8-16 Ohms

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So I have an old Klipsch KG SW sub-woofer I've been schlepping around the country since I bought it in the early 90s, along with my old Pioneer Elite VSX-52 AV receiver I bought at the same time. The sub is a passive pass-through dealy made to be daisy chained between an amp output and the left and right speakers. An early attempt at a home theater LFE, when plate amps we kinda garbage and Dolby Pro Logic (I) was only really sending any sort of bass programing to the left-right mains and center and backs were just really crippled steering speakers, generally supplied by significantly less wattage. Anyway, wired as intended, in never was a very impressive box, it was rated to put out 38-150Hz and always seemed like it was less efficient and didn't go much lower, if at all really, than the speakers I had in line with it so it's internal crossover seemed like it was, I dunno, just moving the same level of bass from one place to another at best with a muddled up gain between the 2.


Quite some time ago, well a few years, I bought a Sony STR-DH850 7.2 AV Receiver and have been gradually filling up the channels with matching vintage speakers (Ohm Acoustics Model Ls), I have 3 pairs now in a surround system, sounds great actually. So I decided to re-look at the old Klipsch after it'd been staring at me from the corner in the basement where it's sat since my last move, more on that in a bit. I bought a power amp off of eBay, a Sony TA-N55ES to power the Klipsch. It does bridged mono, but at 8-16 Ohm load. The Klipsch has 2 dual 4 Ohm voice coil woofers in it and the funky pass-through crossover, which I've never really been sure how the impedance math works with that. Anyway mathematically I should just be able to bypass the crossover, as I'd be using the electronic low pass of the AV receiver, and just wire all the voice coils in series to get to 16 Ohms. However I've seen dozens and dozens of diagrams of wiring multiple dual voice coil drivers together and have never seen one show multiple multi-coil drivers with all the coils wired in series. Is there a reason for this? I mean other than it being kind of a trend to go as low in resistance as you can, well just because?


I know the receiver is a 7.2, with the .2 being key here, and I could just feed both of those into the amp in 'stereo', even though it isn't, and run each driver as a series coiled 8 Ohm, and the sub will only be 5 or 6 feet from the amp. However... I have to go the long way around the room to get there so it may only be 5 or 6 feet away but it's 75 feet of wire in-between, so it's not an insignificant thing to do, I have to buy a whole 100' spool just to get one cable and it's just all the more bulk running around the room. The 75 feet part is also one of the main reasons for keeping it passive, the loss over speaker cable is far less than signal cable at that distance.


The box is about 40 liters, and is a 1:1 bandpass configuration, though plugging the measured dimensions into WinISD I can't see how the 'design' is anything but a wild guess. The ports are pretty much standard, unaltered, off the shelf PA parts 3" Diameter by 5" long, 2 of them. Which based on the two 8" drivers, almost regardless of the specs, just don't mathematically work with the ports. But to be fair the box was made when Sound Blasters were a new product, so I'm guessing simulation software wasn't really a thing yet. The box does seem to have potential to be a better performing bandpass box or even routed out to be a dual driver plus dual passive radiator box. It is well built and tight.



Anyway, the sub has been moved back and forth across the country many times, it was just painted black and looks kinda like a road case and has been treated as such, always just been treated, for moves, like it was it's own crate. So I'm reading this thread on a Klipsch forum and find out these subs came in a bunch of different finishes, not just the utilitarian black mine is. So I though well maybe the wood grain you can see through the black paint is some sort of hardwood plywood, I can stain or something, or at the very least I should just sand it down to repaint it, because it's looking pretty sad these days. So this is what was hiding in plain sight under the black:
 

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I know I can do that, I don't even need a splitter to do that, since it's a 7.2 receiver, it has 2 sub outputs. The issue is not wanting run another 75' of cable.
I just figured using one signal for both channels since both subs are in the same enclosure.
Yes you can wire everything in series. Won't be a problem but you may only get 150W @ 16Ω bridged.
 
I just figured using one signal for both channels since both subs are in the same enclosure.
Yes you can wire everything in series. Won't be a problem but you may only get 150W @ 16Ω bridged.


...and that's fine, I plan to rebuild this sub sometime fairly soon, at which point I'll build it for 8 Ohms, I just want to see how it does, as is, playing on it's own, on it's own amp without the loop through and without the weird crossover. As built, and used as intended, this thing has so many variables going on. But like I said I've not seen a single example of a diagram of anyone attempting to do this, the wiring in series bit.
 
...and that's fine, I plan to rebuild this sub sometime fairly soon, at which point I'll build it for 8 Ohms, I just want to see how it does, as is, playing on it's own, on it's own amp without the loop through and without the weird crossover. As built, and used as intended, this thing has so many variables going on. But like I said I've not seen a single example of a diagram of anyone attempting to do this, the wiring in series bit.
I think that's just because it's not a common scenario. You're trying to do something with what you have, which is great.
 
The amp showed up yesterday, so I got to work on making it all happen, opened up the sub and de-crossovered it. Interestingly, because it was setup as a feed through device, it has 4 sets of binding posts on the bottom, L+R IN and L+R OUT, and internally it has wire leads from the binding posts to the crossover. OK That's easy, each coil can just have it's own set of posts, and that's how I wired it. Clip the leads in the right place and there is no soldering involved, and since this is really a temporary configuration until I rebuild this, I just wire nutted the leads together, it's not audiophile quality, but it's not a permanent solution. So now I can just configure it externally. I looped it up for 16 Ohms, tested it with a short run from the amp, and everything worked pretty well, though gotta say I had to bump up the attenuation on the amp some to really get anything out of it. Then I made and ran the 75 footer, hooked it up, success.



The way it's wired now I could also easily run it as 2 x 8 Ohms, or even 4 x 4 Ohms if I felt like running 300 ft of cable, though I guess technically out of spec for the amp, as that would require using A+B which is again limited to 8-16 Ohms. The amp will drive 4-16 Ohms A or B (Stereo), 8-16 Ohms A+B (Stereo), 8-16 Ohms A or B (Mono), or 16 Ohms A+B (Mono).



Next step, hack the couch so it fits underneath it (not as tricky as it sounds, I don't think anyway). It's one of the advantages of this sub is that it should fit up underneath the couch, the couch is pretty high and empty underneath and the sub fairly low. I should just have to readjust the bottom fabric 'cover' to create a well for the sub to sit inside. Kind of a shame since the sub is all gloriously walnut now to hide it under the couch, but hey I'll know it's there.



Took a bit to actually find something to test it with, I was surprised that a lot of streaming sources seem to have the audio choked out. There is lots of 'surround test demos' on Youtube that aren't really putting out surround and a lot of older movies on Prime Video that seem like they have compressed out the audio track. What ended up being a surprisingly good test was Gotham on Netflix, a very boomy soundtrack.



Calibrated via the test calibration mic on the receiver and used as is (crossed over at 80Hz), there didn't seem to be a whole lot of 'add' by the sub, not until I bumped up the power amps attenuator a bit (bumping it up a lot makes it a pretty lively box actually). Still the sub doesn't really add more than a couple Hz to what the rest of the speakers can do, but it does make it so I can independently adjust the gain of that 36-80Hz range.


So would I really gain that much by running this as 2 x 8 Ohm? The speaker cable I use cost about $50 a spool (99.99% pure copper, high stranded, 12 AWG) and the connectors I use cost about $5 each (Holland gas tight compression connectors + the banana plug tips). So it would be another $70 or so to run another 75 feet to power the sub 8 Ohm "stereo" and if I rebuilt it later I could wire it for 4 Ohm Stereo if I wanted, but what real gain do I get from that? This is all within the specs of the amp, but does this actually make a huge difference? The rated specs of the amp don't seem to show a dramatic gain in the ratings, 2x110W@8 Ohm, 2x150W@4 Ohms plus 1x300W@8 Ohms Mono, seems like 8 Ohms Mono may be the best scenario for headroom. Also if the math is linear it would suggest that the amp should put out around 220W@16 Ohm Mono, if I'm reading it right.
 
Hmm, so modified the couch and the sub fits nicely underneath, well kind of inside of it now, I was afraid it would lessen the effectiveness of the sub, but interestingly it seems like it kind of enhances it. The sofa is 'L' shaped with with this chaise extension which is the part the sub is under, making the sub pretty close to being right in the center of the room. I've played around with crossover points and gain quite a bit, sweet spot seems to be about +3dB with an 80Hz crossover point. Anything less in gain makes the sub disappear pretty quickly, and much more and it gets distractingly lively. I haven't really tried to go lower on the crossover than 80Hz but higher seems to rob the mains and muddy up the transition. Kinda one of the reasons in the first place I've gone with vintage bookshelf speakers, they can hold their own pretty low, so it keeps the sub out of things that don't belong in a sub, like low voices, and such. Keeps it the LFE (low frequency effects) box it's intended to be, basically doing more to add character than content.
 
Hmm, so modified the couch and the sub fits nicely underneath, well kind of inside of it now, I was afraid it would lessen the effectiveness of the sub, but interestingly it seems like it kind of enhances it. The sofa is 'L' shaped with with this chaise extension which is the part the sub is under, making the sub pretty close to being right in the center of the room. I've played around with crossover points and gain quite a bit, sweet spot seems to be about +3dB with an 80Hz crossover point. Anything less in gain makes the sub disappear pretty quickly, and much more and it gets distractingly lively. I haven't really tried to go lower on the crossover than 80Hz but higher seems to rob the mains and muddy up the transition. Kinda one of the reasons in the first place I've gone with vintage bookshelf speakers, they can hold their own pretty low, so it keeps the sub out of things that don't belong in a sub, like low voices, and such. Keeps it the LFE (low frequency effects) box it's intended to be, basically doing more to add character than content.

I want to clarify this. I mean that it is not good that the cut-off frequencies chosen for the subwoofer are far from the maximum low range of the satellites, in reality there should be an overlap between the two, and the smaller that crossing, the more the effect will be perceived that the subwoofer is not present.
80 hertz seems to be a good limit and is recommended by many "experts", but it cannot be generalized., Because it depends on the room, the satellite speakers, the correct location, etc.
So my point is that you say "Kinda one of the reasons in the first place I've gone with vintage bookshelf speakers, they can hold their own pretty low, so it keeps the sub out of things that don't belong in a sub , like low voices, and such. "
ONLY THATS´S what I saw wrong.
My English is very basic, only thanks to Google Translate can I comment here.
But I suppose it is the problem of many, and with a little goodwill they can interpret me. I'm sorry if I expressed myself wrong.
 
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I thought I would post some info about the amp (the Sony one) incase you are not aware of it. Here is your pic of the rear of the amp and the binding posts, along with the advisory about the impedances that can be used:
SONY-TA-N55ES-Stereo-POWER-AMPLIFIER-Bridgeable-Mono-_57.jpg


Typically how this works is that speaker "A" and "B" binding posts are fed by the same amp channel and just connected using a wire inside the chassis depending on a position of the speaker selector switch on the front following these rules:
  • A mode: each of the amp's two channels are connected to the left and right binding posts for "A". The posts for "B" are disconnected
  • B mode: each of the amp's two channels are connected to the left and right binding posts for "B". The posts for "A" are disconnected
  • A+B mode: the amp's left channel is connected to both the left output of "A" and "B" in parallel; the amp's right channel is connected to both the right output of "A" and "B" in parallel
You can see how it works by looking at the amp's schematic from the service manual, page 7. The mode A+B is the same exact thing as if you connected two speakers by wiring them both to e.g. the "A" binding posts. Here is a link to the manual:
SONY TA-N55ES SERVICE MANUAL Pdf Download.

Sony cannot explain this kind of technical stuff to a typical end user, they are too dumb. So they put the warning on the back to remind the user how to safely connect speakers and what impedances can be used.

The reason I brought this up is that if you can connect all your subs into a 8 Ohm load you can use the bridged mono operation. In this case using A or B or A+B is going to look the same from the amp's perspective - there are two channels and they will be bridged into a single load. If that load is 8 Ohms the load seen by each channel is half that, or 4 Ohms, and that is the minimum load this amp can handle for each channel.

This is an old amp. The power supply caps are probably losing some capacitance, and this is what keeps the power up when you demand a lot of it from the amp. So it would be better to use a higher impedance load like 16 Ohms in bridged mode because there is less current draw that way. Of course the amp also can only produce half the power, but try it first and see.

Since you have two dual 4R subs, wire the terminals on each sub in series and then wire the subs in series. This gives you 16 Ohms. Use the amp in bridged (mono) mode. Just use mode "A" and speaker terminals A. Each amp channel sees 8 Ohms.

The other way to do it is to run stereo subs. Connect the terminals on each sub in series so that each one is 8 Ohms. Put the amp into stereo output mode. Connect one to the right A and the other to the left A and choose mode "A" via the front knob. You will need either a mono input signal and a "Y" cable, or stereo left, right input cables for the right and left inputs. Each amp channel will see 8 Ohms just like the bridged configuration above, but you will have stereo bass.

The sound will be about the same either way. This is about the only way to safely use this amp with your speakers.
 
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CharlieLaub


If I could guess what people think .....
Besides, I'm not sure who you're going to ...

If it's me, I have a point to comment on what you say, but first I need to know

I was responding to the first post in this thread. I scanned the other posts to see if anyone brought this point up or not but I didn't see it. Anything of your own posts had absolutely no bearing on my post what so ever.
 
So my point is that you say "Kinda one of the reasons in the first place I've gone with vintage bookshelf speakers, they can hold their own pretty low, so it keeps the sub out of things that don't belong in a sub , like low voices, and such. "
ONLY THATS´S what I saw wrong.
My English is very basic, only thanks to Google Translate can I comment here.
But I suppose it is the problem of many, and with a little goodwill they can interpret me. I'm sorry if I expressed myself wrong.


Not sure what you see wrong with that, the LFEs in a cinema surround system are intended to produce exactly what the acronym implies Low Frequency Effects, theater sound is not audiophile sound, it's a PA system, big, typically horn loaded and peaky, base bins for low frequency. The roll off to the higher frequency drivers is typically not flat or elegant, and are the conditions the original soundtracks are mastered for. They are there for effects, presence, volume and drama.



On the other hand if you are referring to my comment about vintage speakers, this stems from the diversion speaker technology took some 20 years ago. Away from wide dynamic range and towards the whole satellite/sub ideology, which was really done to address a problem that no longer exists, electro magnetic interference with cathode ray tubes. Basically move low frequency drivers out of the speakers so you can more easily shield them and move them closer to the TV and then remote those low frequencies somewhere less disruptive, As putting speakers far away from your video display disassociates the audio from the video, which in turn then reduced stereo imaging so the compromise was the center channel. Point being if you rewind the clock, those speakers developed to create a wide seamless sound stage from only 2 sources perform amazingly well in a surround setup. Placement and 'aiming' become far less critical and the surround 'effect' is far more room filling, this is exactly how surround works in a theater, there isn't simply 20 seats in the middle that experience surround and the rest of the viewers are out of luck. Dolby/DTS are systems designed to encompass the entire space not just for a few select patrons in the middle.



I have, since I wrote my last post, played around a bit more with my setup and have actually brought down the crossover point to 60Hz, flattened the EQ and dropped the gain on the sub a couple dB which has opened up the soundstage quite a bit. My particular sub is only rated from 36-125Hz, though I think I may have gained a few Hz on the bottom just because of how and where it's placed, under/inside a sofa in effectively a large wooden box that's probably 4 to 5 times the volume of the sub itself. It's noticeably smoother and lower than it was in open air, though requires a bit more gain in this location to make it's presence known. The only issue I have now is that 2 of the speakers have less than ideal woofers in them, as they were replaced somewhere along the lines with drivers that do not produce mids very well, I've since moved those to the least ideally placed positions and that also made a dramatic improvement. I plan on re-replacing those drivers with something much closer to the originals that can get up to the speakers original crossover frequencies.
 
The reason I brought this up is that if you can connect all your subs into a 8 Ohm load you can use the bridged mono operation. In this case using A or B or A+B is going to look the same from the amp's perspective - there are two channels and they will be bridged into a single load. If that load is 8 Ohms the load seen by each channel is half that, or 4 Ohms, and that is the minimum load this amp can handle for each channel.

This is an old amp. The power supply caps are probably losing some capacitance, and this is what keeps the power up when you demand a lot of it from the amp. So it would be better to use a higher impedance load like 16 Ohms in bridged mode because there is less current draw that way. Of course the amp also can only produce half the power, but try it first and see.

Since you have two dual 4R subs, wire the terminals on each sub in series and then wire the subs in series. This gives you 16 Ohms. Use the amp in bridged (mono) mode. Just use mode "A" and speaker terminals A. Each amp channel sees 8 Ohms.

The other way to do it is to run stereo subs. Connect the terminals on each sub in series so that each one is 8 Ohms. Put the amp into stereo output mode. Connect one to the right A and the other to the left A and choose mode "A" via the front knob. You will need either a mono input signal and a "Y" cable, or stereo left, right input cables for the right and left inputs. Each amp channel will see 8 Ohms just like the bridged configuration above, but you will have stereo bass.

The sound will be about the same either way. This is about the only way to safely use this amp with your speakers.


Yes, exactly, and something I thought I clearly conveyed in my first and subsequent posts, or even the threads title for that matter. I knew the sub could be wired as 2 Ohm stereo, 4 Ohm mono, 8 Ohm stereo or 16 Ohm mono but only the last two are within spec of the impedance capability of the amp. And given my desire to run the amp mono, the answer is 16. If and when I rebuild the sub I may reconfigure it for 8 Ohm mono with new drivers, but for now my choices are basically 16 Ohm mono or 8 Ohm stereo, and I think mono at 16 is a better use of the amps capabilities and certainly an easier and cheaper solution from a wiring perspective.



I mean I thought the title of the thread made it obvious what the goal was. But, like I said initially, I have seen nowhere where wiring dual voice coils in series and then those two drivers again in series was ever drawn out as an example of something doable, and was simply questioning if there was a legitimate reason why you would not want to do this, and I mean even if the impedance is arbitrary. For example if those dual voice coil drivers had 2 Ohm coils, which exist, wiring all in series would result in 8 Ohms which is certainly something that would be the only solution in a lot more instances I would think, given the alternative of 2 Ohms which is not, by any means, universally supported, in bridged mono, even in modern amplifiers.
 
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