HiFi speaker problems

[merlin]

I have finally got round to fitting a new hifi system with wired in speakers.
The wires were fitted a few years ago while I did a lot of work on the house, I have fitted a pair of speakers in 3 rooms and therefore used a 3 way splitter switch so that I can feed them all from the amp.
The switch I have used is a QED SS30 and it is rubbish as it only works when the speakers are on one at a time or as follows
1 & 2 - good
1 & 3 - good
2 & 3 - rubbish
1 2 & 3 - 1 is good but 2 & 3 are rubbish.
Does anybody know of another make of switch that is available as I cant find one?
Thanks, Merlin

 

[thetyreman]

I found one on ebay https://www.ebay.co.uk/itm/QED-3-Way-Sp ... :rk:7f:0 looks like a good replacement, plus you are covered with ebay/paypal if it doesn't work for whatever reason.

 

[Eric The Viking]

Are you trying to use several pairs of speakers simultaneously, or one set at a time? Paralleling them up isn't a terribly good idea (at low impedance). But it rather seems like they are not all the same. This may be the speakers, the switch, or the wiring.

First off, some basics: have you checked the wiring resistance (impedance) of each of the circuits with a decent meter? It needs to be really low - 1/2 - 1 Ohm for the trip there and back. Also, if you move the speakers between the rooms, and swap the terminals on the switch, does the "fault" seem to stay with the speakers or the wiring (to specific rooms) or the switch positions?

Paralleling-up the speakers isn't a good idea really: with three pairs the impedance drops to around 2.7 Ohms* meaning your amp has to deliver rather a lot of current to each channel to make any of them sound at all loud.

There are, broadly speaking, two or three ways to do this that would work better (probably). You could use three separate stereo amps. You could possibly adapt an AV receiver-type (they have up to seven normal channels in three pairs, plus a centre channel of normal bandwidth and a reduced bandwidth channel for a subwoofer). That ought to give you an overall volume control, which might be nice.

The other alternative, used by professional installers in bigger buildings, is to use a "100V line" system. These let you run a number of speakers off one amp, and work a bit like an audio equivalent of the national grid(!). You have a pair of big 100V line audio transformers on the outputs of the amplifier, and each speaker has a smaller transformer, to drop the audio voltage back down to something that can drive the speaker. Often these smaller transformers have multiple tappings (windings), allowing them to be switched, giving you a local volume control in steps (at the speakers). With a 100V line system you can pretty much use bellwire as speaker cable - I've used microphone cables for that task a lot, with great success.

Audio quality depends on the quality of the transformers, but good ones can be had (but they're not very cheap). Canford sell nice ones.

E.

*That's assuming each speaker is a nominal 8 Ohms, which is fairly normal.

 

[Doug71]

I have a QED SS40 running 4 pairs of speakers around the house and it works fine with any number or combination of speakers on.

I know nothing of the technical side of things but was lead to believe that if I use 4 pairs of 8 Ohm speakers the impedance will never drop below 4 Ohms no matter what combination I have on because the switch sorts it out.

 

[Eric The Viking]

I have a QED SS40...
... if I use 4 pairs of 8 Ohm speakers the impedance will never drop below 4 Ohms no matter what combination I have on because the switch sorts it out.

I am not saying you are wrong, but if it's a passive switch, i.e. one with no logic control or sensing and purely mechanical, I cannot see how this can be achieved.

Of course you could work out a truth table of "allowed" combinations of series-parallel arrangements, each giving four or eight Ohms, and you would have to look up the settings in use. It's still rather nasty though.

Honestly, I'd either go down the wifi/Bluetooth route (with small amps distributed with each pair of speakers), or 100V line. I've been surprised how good 100V line kit can sound though - a bit HF limited, because of the transformer coupling, but I've made studio PA/foldback systems, using high-quality, high-power transformers, which were excellent once the system was EQ'd properly. And wholly in the spirit of not letting things go bang

E.

 

[merlin]

Thanks for your replies Gents, as per normal nothings easy as I thought it was just a case of plugging in a switch!
Eric, thanks for such a detailed reply - it might take a while for me to soak up all these new words but over Christmas I will try.
The speakers are all the same in the ceiling and are 8 Ohms.
It would be nice to use all 3 rooms at the same time, more like back ground than a Disco though.
For the moment I will just plug 2 pairs into the back of the amp and look into your suggestion Eric.
Merlin

 

[merlin]

it was recommended to me that I could use an AV receiver but as the pairs of ceiling speakers are in different rooms it seems a bit of a cop out, plus from what I can see there are things I don't need in there so is that a compromise with the quality of the amp.
Merlin

 

[Eric The Viking]

Assuming the ceiling speakers are identical, I think you have a wiring or connection fault somewhere, based on what you've said (or one of them has a long run of too-high resistance cable). So check resistances, etc. before spending any money, as it may be something very simple.

I can't say whether it's a short- or open-circuit (or at least too-high resistance), but a meter will show you. Disconnect from the amp and switchbox and measure resistance across each speaker in turn at the leads that normally go into the switch. I'd expect to see around 4-6 Ohms, NOT eight Ohms (you're measuring DC resistance of the speaker's coil + the wiring, not the impedance, which is frequency-dependent). Anything below four or above six is worrysome - stick some masking tape on the wire to identify it and return to it. If they all come out roughly the same, it is more likely to be the switchbox.

When you have found issues, you can start trying to identify what they are. Frustratingly you will need to get at the rear of the speakers. Assuming you can do this, I'd put a dead short across each in turn and test again - that will tell you the cable resistance. You can also test the speaker itself, by removing one of the two wires and measuring across the disconnected speaker.

Honestly, 100V line was designed for what you are trying to do. You probably only need 15W transformers (at each loudspeaker), and no more than 100W at the amplifier end. There can be a large difference in quality though - I'd stick with a known brand - Eagle, TOA (if they still make them), Canford (buy British!). You probably won't go wrong with Farnell/CPC either or Rapid. You can't easily see externally the difference between a good and poor quality transformer, so avoid eBay or Alibaba. If there's a choice, go for the music quality or high bandwidth range, which will cost more than the cheaper ones (suitable for only speech).

They usually have multiple tappings, labelled by the power you'd get by using them. You can use these to locally adjust each speaker pair so you get the sort of loudness that suits the room, or wire them to a rotary switch so that it can be adjusted at will. Typically a good 15W transformer would be tapped for (say) 5W, 10W and 15W, giving you 'off' and three loudness options via a switch of your devising.

 

[nev]

My tuppence worth.
Working with what you have i.e. speaker wires all run to one point, no cat 5 or similar, and keeping the cost down.
First try each of the pairs individually connected directly to your amp, that should tell you wether there are any issues with any of the speakers.
Personally, I consider 100V systems for pub toilets etc (sorry Eric ) and of course going down that route that would mean changing everything and spending lots.
You can get multichannel hifi amps (Rotel for instance amongst many) but they're not cheap.
If it were me in the same boat I'd take a 25 quid punt and try something like one of these and if it works well enough grab another two. This would need a pre-out (pair of phono sockets) on your amp. These little amps have an in and an out for the phono feed so you can daisy chain them without any issues. They also have bluetooth so you could probably use them individually to stream anything from phones and tablets etc.

 

[Eric The Viking]

My tuppence worth.
Personally, I consider 100V systems for pub toilets etc (sorry Eric ) and of course going down that route that would mean changing everything and spending lots.

Wrong at several levels.

1. 100V line, done properly is capable of excellent results in practice.

I linked to Canford's own transformers. I note they have dropped their industrial quality range (as far as I could quickly see), and now only sell music quality ones. I couldn't find the spec sheet for their own brand, but the heavy duty Cloud brand ones they sell are quoted as 35Hz-18kHz (-3dB points, whilst dissipating 100W approx.). That's quite a lot better than the practical range of most loudspeakers. Ceiling speakers? 120Hz - 12kHz, probably, and not close to flat response (OK. speakers usually aren't flat but you know what I mean).

I'm not just reading the specs either: I spent quite a while as a professional audio engineer (properly and professionally trained, I might add), both using and occasionally installing 100V line kit. Like everything, cheap == nasty, but 100V line, properly implemented, is flexible and capable of very good results.

High Fidelity? No, not by my definition, nor yours at a guess. But then arbitrarily ganging speakers and using a switchbox at low impedance kicks that one into touch immediately anyway.

100V line is certainly good enough for good quality background music, listening to the radio, whatever. Bear in mind there are hardly any sources nowadays that would stretch a genuine HiFi reproduction chain - certainly not anything broadcast, nor downloaded from the internet, nor most CDs even**. I know the world moves on, but it is unlikely that ceiling-mounted speakers are capable of sufficient quality to "reveal" deficiencies. In a double-blind test with commonly available source material could you tell the difference? Probably not.

2. It's a PASSIVE solution: no need for a replacement amp nor additional mains provision in the various rooms, hiding things in walls, etc. Suitable 100V line transformers for the speakers are only a few cubic inches, and would probably attach to the speaker itself. You could probably buy everything necessary for less than 350 quid*. One properly done mains spur for one amp could easily blow that budget if access is awkward. You don't get the Bluetooth functionality, but that wasn't in the original design spec, and anyway, it comes with the hidden cost of altering the house wiring to accommodate it. Then there's fireproofing, and the possibility of the amps failing: 100V line is inherently safe.

3. The cabling is already run: what's in the walls and ceiling is probably it. Good luck with using phono impedances over long runs in house wiring, never mind getting it in there in the first place, dealing with ground loops, etc. FWIW, I usually leave draw cords in places that have nuisance cable runs (I have four CAT5 patch panels in this property), but even I wouldn't leave one in a ceiling void I wasn't expecting to ever need to return to.

I'm not trying to pick a fight, but please don't disparage stuff unfairly.

E.

* 2x Cloud 100W driver toroidals = 84 quid
6x 20W Canford !00V line speaker xfmrs = 167
VAT = 51
Total: 302 (approx, excluding enclosure for the toroidals and carriage)
Toroidals can be in a wooden box, or whatever suits. I'd keep the QED switch (assuming it's not faulty) and use it to switch on the 100V line side.

**I have mastered a few CDs myself, I've mixed hundreds (probably thousands) of hours of broadcast material, both live and recorded, and I know of Grammy-winning stuff with shocking, rookie engineering blunders in it. You'll really struggle to find HiFi recordings these days, unless you buy from specialist record labels (on CD), or originate it yourself at 16@44/48 or 24@96. Then there's the tricky matter of finding a location to record in that's quiet enough...

 

[nev]

Hi Eric,
As prefixed, just my tuppence worth, not trying to start an argument. If you've fitted one 100v setup that's one more more than I have, but I have replaced a few when customers weren't happy with what they had, and I've not heard one I'd like to live with but maybe they were all carp ones.
I used to install multi room hifi, mainly Linn equipment, but a few others too. This was pre the wireless revolution and the cat5 was control wire linking various units not to carry sound.
As you can see by the 20 quid amp suggestionI wasn't going to for 'Hifi' quality for the purists - and no in wall/ceiling speaker setup ever would be.
My suggestion may have been unclear but the thought was to place the amps at the hifi end, use the existing speaker wire , speakers and hifi. The only additional expense or work would be a phono cable with the end chopped off and daisy chained through the inputs of the amps.