Surround Sound

[anchorman]

It is possible to wire the rear Speakers in series with the front Speakers in order to reveal the dolby soundtrack. I do it at home and I have done it in a car in the past.

Of course you lose the rear channels but I'm not sure how much difference it would make. Does anybody know if it would generate any undue load on the amp? After all it is only revealing the sound track and not amplifying it - raw dolby if you like. Apparently the new LR is available with a 14 speaker Kenwood/Dolby arrangement but part of the secret is locating the Speakers properly.

I also notice that the US have an option of a 9" sub woofer in the back door. Does anybody know how it's driven?

Need to get the best from this new Eagles CD!!

[Jinxed]

It is possible to wire the rear speakers in series with the front speakers in order to reveal the dolby soundtrack. I do it at home and I have done it in a car in the past.

Of course you lose the rear channels but I'm not sure how much difference it would make. Does anybody know if it would generate any undue load on the amp? After all it is only revealing the sound track and not amplifying it - raw dolby if you like.

erm.... I don't think this is quite correct... I'm no expert by any means but if you wire the Speakers in serial doesn't this double/ or is it halve the impedance? Im fairly sure it does and if this means the Speakers are outside the correct operating range for the amp then you at least run the risk of repeatedly activating any protection circuitry in the amp and at worst can permanently damage the amp.

And if im wrong I guess i'll learn summat here :)

[dave.m]

Now you've got me thinking back to my DJ days :D :D

If I remember right you need to get the resistance right (ohms law) In other words you can

connect two 8 ohm speaker into one channel, but not two 4 ohm Speakers. Cant remember

the formula but I'm sure the higher you go its ok.

[dave.m]

It is possible to wire the rear speakers in series with the front speakers in order to reveal the dolby soundtrack. I do it at home and I have done it in a car in the past.

Of course you lose the rear channels but I'm not sure how much difference it would make. Does anybody know if it would generate any undue load on the amp? After all it is only revealing the sound track and not amplifying it - raw dolby if you like.

erm.... I don't think this is quite correct... I'm no expert by any means but if you wire the Speakers in serial doesn't this double/ or is it halve the impedance? Im fairly sure it does and if this means the Speakers are outside the correct operating range for the amp then you at least run the risk of repeatedly activating any protection circuitry in the amp and at worst can permanently damage the amp.

And if im wrong I guess i'll learn summat here :)

Jinxed, I'm no expert either but I think your right about how they are wired ie in parallel. Allthough I do think the impedence does get halved.

I'm pretty sure I allways went for 8's or 16's as 4's were a heavy load.

As for the sub woofer I had, the two channels from the amp fed the sub unit. The satellite Speakers were then fed off the sub, all channels

were marked to make idiot proof. ;)

[anchorman]

It was something I first picked up from one of the hifi magazines. The article was advertised on the front page as "Dolby Surround for £1" and inside went on to explain that the dolby track is laid over the existing track simply out of phase with the front track. The £1 referred to a volume switch from tandy at the time but I just use a switch. I have it working in my lounge and have done for some considerable time with no damage to the old sony amp and the effects are very good. When playing CD's you can hear all sorts of backing vocals and instrumentals that are other wise embedded in the front track and so effectively lost.

The wiring is as follows. Loop a single wire from the positive on either front speaker;

Run this round to a speaker at the back of the room. I bought these Jamos for about £40 from memory;

Connect the wire from the positive of the front speaker to the positive on this speaker;

Then from the negative on this to the negative on the other rear speaker and then from the positive on the other rear speaker back to the positive on the other front speaker. You can use any Speakers and it really is effective.

Now that is all OK on my old sony amp and I know for a fact it works in a car because I have done it but not a Newish RAV still under warranty. I don't think the Speakers are driven particularly hard as it is pure passive dolby sound without being either amplified or delayed as it would through a processor.

So my question is - is there any risk?

[dave.m]

I used to read the mags as well, but stopped as I was getting convinced the system I had was crap according to the mags.

Where a year before they were praising it

Also found the kind of improvements they were talking about or should I say NUANCES I would never hear anyway. After

nearly 30 years in an engineering co. my hearing aint as good, and I'm sure that applies to a lot of people.

I think what you've done with your hifi Speakers is a bit like bi-wiring them.

[JHRC]

Hi Anchorman,

The way you have connected your speaker are in parallel, this will half the resistance of 2 speaker with equal resistance ( 2 speaker 8ohm = 4ohm) which will reduce load on the amp to your Speakers. but could blow your speaker if you increase your volume too much.

With series circuit look at christmas tree lights 6volt x 40 =240volts,

or your car batteries 2 x 12 volts batteries connected positive to negative you get 24 volts,

in parallel you would 2 x 12 volts you would get 12 volts connected positive to positive & negative to negative but increase your amps.

This is why your speaker in the house is working O.K. Just a simple mixup of series and parallel circuits.

Have I confuse you with this explanation if so I am sure shcm will keep you right.

Jim

[shcm]

Ok, I'm not big into audio power amp design, but here goes (probably full of errors).

What Anchorman is describing is here (mostly figures 6 and 7):

Click - Surround

It's cheap and cheerful surround decoding up to a point. Channel separation is not great. If it sounds OK to you and you like it, then I say why not!

So are you going to damage something, like the output stage transistors?

Very over simplified circuit is something like this (those with an elec phobia look away now):

It's not such a simple series or parallel speaker combination.

The following basic DC analysis is a vast over simplification. I could get ripped apart for it by those in the know!

First, You might need some basic physics:

Ohm law Voltage=amps * impedance (resistance). V=IR or I=V/R

Resistor in Series: Rseries = R1 +R2 + R3...............

Resistors in Parallel: 1/Rparallel = 1/R1 + 1/R2 + 1/R3............

Q1 & Q2 are output transistors for left channel. Q3 & Q4 are output for right channel. Just imagine them as switches. Q1 is a switch to +V. Q2 a switch to -V. Q1 and Q2 are never on together.

I'll use 8ohms Speakers (=8R in the diagram)

As a normal stereo output (SP1 and SP2 are not present) current flows from +V through Q2 and SP3 to GND or from GND through SP3 and Q1 to -V. Either way the current sourced by Q2 or sunk by Q1 is V/8R. Likewise for the other output.

For the surround case, worst case is Q2 on and Q3 on. Current flows:

1. From +V through Q2 and SP3 to GND

2. From +V through Q2,SP1,SP2 and Q3 to -V

3. From GND through SP4 and Q3 to -V.

Total current sourced by Q2 is now V/8R + (V-(-V))/16R = 2V/8R. Current has doubled compared with stereo case.

Effectively it can be considered a load (speaker) with half the impedance. e.g. a 4 ohm with surround instead of an 8 ohm as stereo.

If you used one speaker in place of SP1 and SP2 current would increase to 3V/8R - 3 times the stereo case (8/3 ohms).

Pull too much current and you'll start getting distortion (output stage over driven or power supply can't cope), possibly transistors will get hot and/or let the magic smoke out.

In practice it will probably never be this bad and therefore if you have a reasonable quality amp and you don't use it at high volume you should (and do) get away with it.

Speaker impedance anyway wanders all over the place due to inherent resistance,inductance, electro-mechanical interaction and compensation networks.

There's some proper speaker modelling here:

Click - Speaker impedance

Clear as Derbyshire mud?

Anything you do is at your own risk!

Take it easy

(don't let the sound of you own wheels drive you crazy).

[anchorman]

Ok, I'm not big into audio power amp design, but here goes (probably full of errors).

What Anchorman is describing is here (mostly figures 6 and 7):

Click - Surround

It's cheap and cheerful surround decoding up to a point. Channel separation is not great. If it sounds OK to you and you like it, then I say why not!

So are you going to damage something, like the output stage transistors?

Very over simplified circuit is something like this (those with an elec phobia look away now):

It's not such a simple series or parallel speaker combination.

The following basic DC analysis is a vast over simplification. I could get ripped apart for it by those in the know!

First, You might need some basic physics:

Ohm law Voltage=amps * impedance (resistance). V=IR or I=V/R

Resistor in Series: Rseries = R1 +R2 + R3...............

Resistors in Parallel: 1/Rparallel = 1/R1 + 1/R2 + 1/R3............

Q1 & Q2 are output transistors for left channel. Q3 & Q4 are output for right channel. Just imagine them as switches. Q1 is a switch to +V. Q2 a switch to -V. Q1 and Q2 are never on together.

I'll use 8ohms speakers (=8R in the diagram)

As a normal stereo output (SP1 and SP2 are not present) current flows from +V through Q2 and SP3 to GND or from GND through SP3 and Q1 to -V. Either way the current sourced by Q2 or sunk by Q1 is V/8R. Likewise for the other output.

For the surround case, worst case is Q2 on and Q3 on. Current flows:

1. From +V through Q2 and SP3 to GND

2. From +V through Q2,SP1,SP2 and Q3 to -V

3. From GND through SP4 and Q3 to -V.

Total current sourced by Q2 is now V/8R + (V-(-V))/16R = 2V/8R. Current has doubled compared with stereo case.

Effectively it can be considered a load (speaker) with half the impedance. e.g. a 4 ohm with surround instead of an 8 ohm as stereo.

If you used one speaker in place of SP1 and SP2 current would increase to 3V/8R - 3 times the stereo case (8/3 ohms).

Pull too much current and you'll start getting distortion (output stage over driven or power supply can't cope), possibly transistors will get hot and/or let the magic smoke out.

In practice it will probably never be this bad and therefore if you have a reasonable quality amp and you don't use it at high volume you should (and do) get away with it.

Speaker impedance anyway wanders all over the place due to inherent resistance,inductance, electro-mechanical interaction and compensation networks.

There's some proper speaker modelling here:

Click - Speaker impedance

Clear as Derbyshire mud?

Anything you do is at your own risk!

Take it easy

(don't let the sound of you own wheels drive you crazy).

Ladies and Gentlemen........

He ma man ;) Not only does he know about stuff you can't see but can throw in the odd Frey/Henley line!

Very interesting articles as well.

And thanks to Mr Jim for spotting my deliberate (oops) error. To my fuzzy logic they are kind of in series but parralel as a pair

You've gone to a lot of trouble and I understand somewhat better but from a warranty point of view, I'll think about whether I'll do anything for a bit longer.

Cheers

[dave.m]

Ah, just as I thought then

Actually the science/ engineering of Speakers is quite fascinating. I have long been a fan of Tannoy Speakers. I was lucky enough because we do

work for them, to get a tour of their factory a couple of times which is near here. Quality stuff, they make Speakers for Japan the size of wardrobes.

The Japs, for all they can make quality hi fi's apparently cant make high end or studio stuff. ;)

[Fujisan]

(those with an elec phobia look away now):

Too late .....I looked

[shcm]

Actually the science/ engineering of speakers is quite fascinating.

Yeah, I'm with you there Dave. I've never studied it in great detail, but I have the feeling it's an "interesting" combination of electrical/mechanical with a bit of gas stuff thrown in. Amazing that they work so well. Possibly one of the weakest things in the audio chain these days?

(those with an elec phobia look away now):

Too late .....I looked

Sorry Fuj, hope you are not too traumatised. . Perhaps Anchorman can post the innards of of a Saturn V rocket engine or something, which would scare the **** out of me. Mind you I suppose it is only plumbing :D

[dave.m]

Yeah, I'm with you there Dave. I've never studied it in great detail, but I have the feeling it's an "interesting" combination of electrical/mechanical with a bit of gas stuff thrown in. Amazing that they work so well. Possibly one of the weakest things in the audio chain these days?

Just shows how sad I am, had to stop buying the mags etc. It gets to the stage when you are listening to the equipment

rather than the music Anyway who's still got a turntable ?

[shcm]

Anyway who's still got a turntable ?

Actually, er Although last time used about 5 years ago.

Oh, no, :o Careful Dave there is also a potential steam engine reference there. Hopefully it won't be noticed

If you start on about painting the edges of CDs green and using directional interconnection cables, I'm afraid I will have to you. :lol:

[Parts-King]

Need to get the best from this new Eagles CD!!

You old rocker Anchorman :D :D :D

Kingo

[dave.m]

Actually, er Although last time used about 5 years ago.

Oh, no, :o Careful Dave there is also a potential steam engine reference there. Hopefully it won't be noticed

If you start on about painting the edges of CDs green and using directional interconnection cables, I'm afraid I will have to you. :lol:

gold plated connectors, spikes on speaker stands its all coming back

Turntable ? wish I had kept mine. and my 400 lp's, 300 12" singles, 2500 singles...............................

Speaking about which, the BEST turntables in the world (Linn ) are made about 20 miles from here.

Unfortunately I did not get a factory tour for this one. Just as well as they were way out of my league

(bit like a T180 then ).

[anchorman]

Anyway who's still got a turntable ?

Actually, er Although last time used about 5 years ago.

Oh, no, :o Careful Dave there is also a potential steam engine reference there. Hopefully it won't be noticed

If you start on about painting the edges of CDs green and using directional interconnection cables, I'm afraid I will have to you. :lol:

Who? What? Yes in Buxton last week and allegedly another one this week;

[chatman]

Anchorman is that you in your overalls and cap..... :lol: :unsure:

[bothwell_buyer]

Sorry chaps - just had to come intae this thread as yer a' wastin time.

In ma propane propelled minibus, I have 2 massive 1m tall speaker cabinets; a 500w amp; 12 channel; with an input of course fur ma CDs as weel; an run off a 2.5KW petrol generator. (Cannae be bothered converting the genny tae run aff propane and a lead frae the hoose would be a problem). Turned up fu volume wi the size of woofers, gives a delicious heart-thumping beat to anything. Course its normally used fur the beat fur the cheerleaders tae dance tae but.

Onyway, its mair powerful than the Beast of Bolsover shouting in the Commons! - Oor Dennis...

No - ye dinna hear the genny running either.

Whit wis that ye said?

[Fujisan]

(those with an elec phobia look away now):

Too late .....I looked

Sorry Fuj, hope you are not too traumatised. . Perhaps Anchorman can post the innards of of a Saturn V rocket engine or something, which would scare the **** out of me. Mind you I suppose it is only plumbing :D

I've recovered now!

Please wait a few seconds for Video to load!

[Fujisan]

Anyway who's still got a turntable ?

My old turntable is sat 6ft away from me, high on a shelf, gathering dust with the twin cassette deck

Who? What? Yes in Buxton last week and allegedly another one this week;

She's a beauty! Any detail's Anchorman? :)

[duncerduncs]

Who? What? Yes in Buxton last week and allegedly another one this week;

She's a beauty! Any detail's Anchorman? :)

Fuji

It boils water, therefore it's a kettle... :P

(that's all the details you need!)

[Fujisan]

Fuji

It boils water, therefore it's a kettle... :P

(that's all the details you need!)

Ahh, but what a beautiful kettle.......every home should have one

[dave.m]

:( :( :( :( Speaking about Speakers (pardon the pun) the last male bastion has come to an end. Been doing a bit of decorating etc upstairs.

Re shuffling furniture etc about and came to the conclusion that the real hi fi had to go. The Tannoy Speakers on the real haeavy stands made

by the company I work for, and the seperates now being disposed of. We now have two piddly little micro systems, one up and one down.

Dark side of the moon will never sound the same

[Fujisan]

Dark side of the moon will never sound the same

Cheer up Dave, it'll always be with us. :D