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Dumb move from speaker wiring novice

 

New member
Username: Monk151

Post Number: 1
Registered: Mar-16
So, I'm pretty sure I know what needs to happen here. But before I potentially make another dumb move, I thought I would check with people who know better.

I wired (attempted) two pair of in ceiling/in wall speakers in my now freshly painted basement project in hopes of helping drown out the noise from our toddler, dog, and us stomping around on the old squeaky wood floors directly above. Nothing fancy, two 8ohm speakers in the bathroom wired to a volume control and 2 of the same in the wall of the main living area with wires sent directly to where the receiver will eventually be.

What I realized as I went to wire the volume control in the bathroom this evening is that I only ran two 14 gauge wires from the receiver to the volume control... I'm pretty sure there needs to be 4. Bummer.

So before I cut into the drywall and fish another two wires in, is there anything obvious I am overlooking that might save me the trouble? Or should I just get to it?

Thanks in advance.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18193
Registered: May-04
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Before I can answer your question, I need to clarify your intentions.

As I read your post, what you have done is send one pair of speaker cables to the location of a single volume control.

However, you have two pairs of speakers in the overall "area".

Correct?



If so, then your issue is how do you intend to use "the area"? An "area" in this regard is anything you wish it to be.

An "area" can be multiple sets of speakers all of which are controlled by one device; a single switch or volume control.

An "area" can also be multiple speakers in one common space with multiple volume controls where all speakers are receiving the same program content. The use of "common listening material" would then define the area as one single, larger usage space.

The latter could (would often be) be a large room/area (a single, large outdoor "area" is the most common type here) with multiple speakers sets where, say, entertaining might occur.

(The thing to consider when you introduce "entertaining" to the concept is the flow of people over time. Early on in the event, people are crowded into "this" space while later in the event those people have moved on and broken up and now exist in "that" area or "those" areas. Ideally, a whole house system has controls which allow the discrete adjustments required to compensate for this traffic flow issue.)

You would send the same (common) program material to all the speakers in one large area but, for the control of more discrete areas of the room, you would install multiple vc's allowing you to raise and lower individual levels as the people accumulate or disperse throughout the event.

The individual controls would have multiple, discrete wiring runs that are all sent to one common "homerun" location for the amp or switch box.

So understand the concept of an "area" is somewhat flexible.



If, in your case, you are using the entire living space as one area, it's entirely possible one volume control will be all you need.

The caveat to this is, if both sets of speakers are identical, we can assume both sets will play equally loud with the same amount of Voltage applied to their inputs and will present an equal impedance load on the amplifier.

This connection (with a single vc for both speaker sets) would prohibit the adjustment of levels for either individual speaker set. Both sets will play at equal volume at any time when used with "common" listening material.

Given the fact the bathroom is considerably smaller than the overall room, and not much conversation occurs in that space, the volume level in the smaller room may be quite loud despite the larger room remaining at only comfortable levels.

In that case, you would want to install a second vc in the larger room with cables run specifically to it from the receiver/speaker switch box.



I would begin at this point to suggest an autoformer type switch box or autoformer type volume controls in this set up.

As you continually add more speakers to the set up, the connection must be made in either a series or a parallel network. Both have advantages and disadvantages.

You could, of course, do your wiring scheme in a combined series/parallel network but that's largely impractical for audio use IMO. And it's a total pain to troubleshoot should problems arise down the road.



The most typical wiring network is to simply add speakers through a parallel connection network. Unfortunately, parallel wiring will result in an impedance drop (by roughly half) each time another set of speakers is added to the system's operation. Therefore, two pairs of 8 Ohm speakers playing simultaneously will drop the impedance load on the amplifier down to a nominal 4 Ohms. Most modern solid state amplifiers don't care much for an 4 Ohm load.

Add to that the included impedance of the vc's and you can easily begin to stress your amplifier by making parallel connections to your whole house speaker network.

The answer to giving your amplifier a break and not risking damage to your equipment is to place an "autoformer" between the amp and the speakers.

An autoformer will maintain a consistent impedance load on the amplifier outputs. That is, more or less, its sole purpose in life, to be as consistent as is technically possible.

An autoformer switch box is your best bet since it will be the one single load value shown to your amplifier. No matter how many sets of speakers are in use at any one time, the amplifier can be shown a constant 8 Ohm load through the use of an autoformer type switch box.

Autoformer vc's are your second best bet though adding up the impedance of the vc's is still an issue of impedance drop as more speakers are added to the system's operation.



You've not described your entire set up so it's not possible to make a solid suggestion which would be better for your set up (vc's are considerably cheaper than switch boxes) though a switch box fitted with autoformers is always the ideal way to control program distribution through whole house/multiple area systems.



Back to your present question; you only need the present (single) wiring network if you do not foresee a situation where you would want to set independent levels in the bathroom and the larger room.

However, if you feel you would ever prefer to have two independent levels, one for each space, then yes, you will need to fish another set of speaker cables to a location in the larger room where a second vc can be installed.


Does that answer your question?



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Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18194
Registered: May-04
.

https://www.ecoustics.com/electronics/forum/home-audio/728674.html
 

New member
Username: Monk151

Post Number: 2
Registered: Mar-16
Thank you for the detailed response. Yes, you've answered my question and created a few more.

To answer your first question, yes, I wired one pair of speaker wires from the receiver to the bathroom volume control (the only volume control) to power an 8ohm pair of speakers in the ceiling. In addition, I have one pair of 8ohm speakers in the studio wall, each with a pair of speaker wires sent directly to the receiver location.

This will be the entirety of the speaker system and all speakers will be acting as one area. Nothing beyond the speakers, volume control (osd svc -100) and wire (16awg) has been purchased yet; there will be budget considerations once the rest of the project gets close to completion.

My plan is to have the 420ft² walk-in basement (300ft² studio living area w/bed & kitchenette, 70 ft² bath, 50 ft² utility room) act as one area, as a guest quarters/short term rental. The function of all speakers will be providing low/medium volume, music and TV audio in the studio and bath. The program content will always be the same to both sets of speakers.

My plan was to have a Bluetooth device in the studio so guests can use their phone for music and some level of master volume control (if possible?), while being able to reduce the volume in the bath manually, being a smaller area.

Although from your advice, and thinking about the overall practical use, it makes sense to cut in wires for vc for the speakers in the studio area, allowing both sets to have independent volume control.

So, I will wire the bath vc without running any additional wire, and adjusting the volume control switch settings accordingly whether I go parallel or in series.. sounds like series might be a better way.

Anyway, if I run the bath vc in either series or parallel, do I have to match the wiring in the studio vc, keeping both sets of speakers on an even playing field? Also, Do I need the same type of volume control in both rooms? Should I bag the SVC-100 and get 2 autoformer vcs?

I'm sure these questions have answers depending on unknowns of not yet purchased equipment, and I'm sure there is a whole load of things I haven't considered. But please keep in mind I'm shooting for simplicity and functionality with a touch of affordability. Any suggestions or ideas or questions to help me make this work are very welcome.

Thanks again for your time.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18195
Registered: May-04
.

"Anyway, if I run the bath vc in either series or parallel, do I have to match the wiring in the studio vc, keeping both sets of speakers on an even playing field?"


I don't understand what you mean by matching wiring.

If you are asking should the cables be of equal gauge, that's not all that important unless the length of the runs is exceedingly different.

Over longer runs there is a bit of a Voltage drop as signal must travel over less copper (higher gauge). You can find out approximately how much Voltage you will lose over what length of cable but, in reality, Voltage drop is still rather a minimal concern since the drop is (essentially) full frequency and equal frequency in its effect.

In other words, Voltage drop over length is not really a frequency selective issue, all frequencies are affected more or less equally, just the level is being lowered. Therefore, using a 18AWG cable here and a 16AWG cable there isn't going to matter much until the runs are well over 100-150 feet.

Keep your cable runs as equal in length as is practical. But do not coil any extra cable as that can introduce issues of inductance which can affect sound quality.

So a 100' run and a 125' run are fine together. Even a run of 25' across the room and 100' to the outdoor speakers is OK with the same gauge cable.

If you have, say, a 25' and a 200' run, the system can accept that difference as long as the gauge has been increased for the longer run. Adding more copper by increasing the physical gauge of the cable (lowering the numeric value) will minimize the total resistance of the cable run, making life a bit simpler for the amplifier.

You no doubt grasp "resistance". Like when you tell your wife you want to spend this year's vacation fund for that one time purchase of the 200" projection TV over the 45" LED she found on sale.

That's how the amplifier views "resistance" too. Things can get heated if a compromise isn't reached.


Any excess cabling should be laid out in a soft "S" or "figure of 8" type shape rather than being coiled.

Total capacitance and inductance of a cable can affect sound by rolling off high frequencies and, in the case of very high capacitance cables, even sending the amp into oscillation. It would be rather difficult to find speaker cabling suited for in wall use that is too high in either value.



Most cabling sold for in wall audio installations will be a twisted pair or multiples of twisted pairs if you are running one "snake" type cable to one location and then splitting the cable open to run to multiple locations downstream.

This is fairly common usage in whole house distribution systems and there's little to be concerned about when using such cables.

Mixing brands of cable is fine though I am of the opinion some cables are slightly higher quality than others. When a budget is a major concern, buying, say, a "Belden equivalent" cable is acceptable. Belden though is still the gold standard for cables and, when the budget allows its use, its your safest bet IMO.

If you are actually "pulling" cables through a run, the composition of the outer jacket makes a difference and even two companies saying they use the same material, typically PVC, will pull differently when you begin to consider cost. That's just one more reason to use Belden or a good quality equivalent.

Unless you are running around corners and through tight gangways, moving up to a Teflon outer jacket isn't typically required or suggested for whole house systems.



The thing about cables is they aren't really going to matter much as long as you are using them in a system intended for background music levels. No one sits down and focuses their attention on background music to pick up nuances within the performance.

In your main audio system, cables matter. In your basic hookups for even a whole house system, don't cheap out. Crappy connectors will oxidize quickly and cause issues down the road that will drive you nuts. Buy good quality but don't buy into much of the hype of cabling when it comes to a whole house system.



Be aware of your cable layout if you are placing cables inside walls prior to an electrician or, most especially, a drywall installer coming onto the property. They are working on an hourly rate and they won't bother moving or even avoiding your cabling.

Drywallers tend to run staples through whole house cabling (just for the fun of it IMO) so make sure your cables are set back far enough from the face of the studs to make this less likely.

Volume controls or any location where you break open and terminate a cable should be placed as far away from an open AC line as possible.

Cross AC lines with a perpendicular. Do not run audio cables parallel to AC cables if you can avoid it.

If you must run parallels, provide about 6" of distance between the cables whenever possible.

There are a few local codes concerning whole house audio/automation systems. Familiarize yourself with them. Neither system has high potentials for fire risk but you can get yourself into a situation where RFI (radio frequency interference) becomes an issue which requires re-doing cable runs after the drywall is installed. Codes minimize this potential risk.

Does that cover it?




The SVC-100's from Niles are autoformer type controls. Stick with them in even your tightest budgetary constraints.

With an af type volume control you can stabilize the load on the amp when more than one pair of speakers are being run off the single vc.

In other words, you can daisychain a half dozen speaker pairs off the vc and the af tap will allow you to select a single constant impedance load shown to the amp.

However, each vc at that point becomes "the load" on the amp.

The issue then becomes, how do you network all the vc's in your system to show your amp a single stable load?

You can wire in series/parallel networks but, as I said, they require some calculations on your part and they are a PITA to trouble shoot should problems arise.

Very old fashioned Xmas tree lights are an example of a series network. They are fine in terms of making the load stable but they are an all in/all out type of network.

Once any one component in a series network fails or is switched out of the signal path, everything stops working all together. That's bad enough with lights. When whole house audio systems are the issue, they become such a headache your local liquor retailer will eventually know you by name and have the gallon jugs ready when you pull up.



Let's say you've taken two af type vc's and they are both set to their "8 Ohm" tap. If you connect those two vc's directly to your amplifier (or through a cheap switch box where all the switches are networked in parallel), it's more or less the same as running two sets of 8 Ohm loudspeakers in parallel to your amplifier outputs.

The parallel connection establishes a dropped impedance of roughly half the individual loads. Therefore, two 8 Ohm loudspeakers connected in parallel will result in roughly a 4 Ohm load.

Most solid state receivers don't want to see a 4 Ohm load.

More current (Amperage) is required as load impedance drops and most receivers, and certainly most modern AV receivers, don't have a power supply of sufficiently high quality to drive higher current over longer periods of time.

The amplifier runs hot as it struggles to deliver current rather than Voltage and eventually the amp shuts down rather than allow itself to self-destruct. That's a very annoying habit when you are entertaining.

There's a lot more to this than simply seeing all 4 Ohm loads as bad and all AV receivers as not up to the task but, the capsulization of the issue is, most modern AV receivers will be most content with a stable 8 Ohm load.

You can set each af type vc to present a stable 8 Ohm load no matter how many loudspeakers are running from that one vc. The issue is, how do you connect more than one af type vc to your amplifier?

This is where your af type switch box comes into use.

Rather than driving several af type vc's off your amplifier, the switch box shows one simple, single, stable load to the amp.

Whatever you set as the single load impedance of the switch box is what the amplifier sees.

After that, you could, in theory, load the switch box with 25 speaker pairs and as many af type vc's as there are outputs on the switch box and the amp would still only be faced with the single load of the switch box, which you will set to be an 8 ohm load.



Obviously, there are issues of just how much wattage you have available and how many speakers will be driven at any one time but, this is how the theory of an autoformer operates. It is the modernization of the 25V and 70V distribution system of old; https://www.ecoustics.com/electronics/forum/home-audio/719045.html

AF type switch boxes are not cheap and you don't want to buy the cheapest af type switcher. But they protect your system and that will save you headaches and time down the road.

Placing af type vc's on the output side of an af type switcher is normal practice. The fact the vc's are using af's in not the issue at that point unless you are daisychaining together a half dozen speakers onto one vc.

You use the Niles af type vc's because they are great controls for a moderate amount of money. They won't become noisey over time and they won't normally wear out in the lifetime of the system. You use them because they're worth the money.

There are also af type switch boxes with vc's at the switch box. In your current set up, this might be a consideration which wouldn't require more cabling. This type of switcher though is a bit of a pain since you have to be at the switcher to set appropriate volume levels. When the vc and the loudspeakers are a distance apart, that hardly ever works out for the best.



How's that?


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