Do I need 4ohm's or 8ohm's for a 4-speaker setup?

[swee'pea99]

I remember reading that my Harmon Kardon system, which has 2 speaker outputs, can actually run 4 speakers (with appropriate connectors) as long as they're 4 ohm, or 8 ohm, speakers...problem is, I can't remember which! Anyone know?

 

[Red Light]

I would have thought 8 ohms. Wired in parallel two 8 ohm speakers will represent together 4 ohms.

 

[2PedalsTez]

Iirc the impedance of the speakers must not be below that of the amp.
Not sure how that works with fitting two pairs of speakers into one set of connections. Would it be worth buying a basic switch box that allows spkr 1, spkr 2 or both?
Either way, I like Harmon Kardon kit

 

[henshaw11]

Which amp exactly ? - a quick browse on the Harman website at one amp lists what impedance it'll drive*, I daresay if it's an older model there'll be a user guide for it on there.

*plus what power it'll deliver into that impedance - IIRC the amp I found handles down to 1 ohm - but yours may well be different.

(Two 4 ohm speakers in parallel will be equivalant to 2 ohms)

 

[swee'pea99]

Thanks. It's all a bit over my head. I have, eg, no idea what 'speakers in parrallel' means. I had in my ignorance assumed there'd be a general 'obvious' answer. Apparently I'm wrong. What a surprise! FWIW, it's called a Festival 300. I have tried googling, but haven't come up with anything useful.

 

[sheddy]

Unless you need disco sound levels it won't matter

 

[henshaw11]

hmm...I seem to be able to find a service manual on one site, and a reference to it on a german forum, but not much otherwise, and nother on the HA website

http://www.diyaudioa...com/FAQ/Wiring/

-see diagram a little way down, next to How do you run speakers in parallel?
(edit - paste worked.. - that's showing two, 4 ohm speakers in parallel as in the text - that's effectively 2 ohms)

the terminals of the speakers may be marked +, - or coloured black, red. For simplicity just match up red/+ on amp with those of speaker on left, ditto for black/-. Likewise for right speakers.

Best mail Kardon and see what they say. Almost certainly it'll handle 4 ohms per channel (ie two 8 ohm speakers in parallel, each side). 2 ohms per channel (ie two 4 ohm speakers in parallel, per side) could be too low if it's not been designed for that.

Aha, found the service manual:
http://users.telenet.be/u078055/Harman Kardon Festival 300 Service Manual.pdf

Spec lists it as 35W into 4ohms, so you can use a minimum load of either
a) one, 4 ohm speaker per channel.
or
b) two 8 ohm speakers (wired in parallel) per channel (effectively 4 ohm)

(you can also use a single 8ohm speaker per channel, or wire two 4ohm speakers in *series* to give you a total of 8 ohms - per side of course)

Hope that's clear enough

 

[Black knight]

Be aware of speaker sensitivity. If they are less sensitive i.e 80 or less it will be more difficult for the amp to drive them.

Best test is just see how warm it gets. Warm to the hand is ok, hot is a no go.

Laptop cooling pad/fan often works well.

 

[subaqua]

hmm...I seem to be able to find a service manual on one site, and a reference to it on a german forum, but not much otherwise, and nother on the HA website

http://www.diyaudioa...com/FAQ/Wiring/

-see diagram a little way down, next to How do you run speakers in parallel?
(edit - paste worked.. - that's showing two, 4 ohm speakers in parallel as in the text - that's effectively 2 ohms)

the terminals of the speakers may be marked +, - or coloured black, red. For simplicity just match up red/+ on amp with those of speaker on left, ditto for black/-. Likewise for right speakers.

Best mail Kardon and see what they say. Almost certainly it'll handle 4 ohms per channel (ie two 8 ohm speakers in parallel, each side). 2 ohms per channel (ie two 4 ohm speakers in parallel, per side) could be too low if it's not been designed for that.

Aha, found the service manual:
http://users.telenet...ce%20Manual.pdf

Spec lists it as 35W into 4ohms, so you can use a minimum load of either
a) one, 4 ohm speaker per channel.
or
b) two 8 ohm speakers (wired in parallel) per channel (effectively 4 ohm)

(you can also use a single 8ohm speaker per channel, or wire two 4ohm speakers in *series* to give you a total of 8 ohms - per side of course)

Hope that's clear enough

and don't always trust the pos and neg signs as being correct for in phase movements of the coils. always test using a watch battery 1.5V and see which way the coil moves then connect as required. speakers out of pahse will cause destructive interference and the sound will be awful.

 

[henshaw11]

Good point - if the speakers are all of the same type then they should be wired identically, but odds are he'll have two different pairs.

 

[subaqua]

Good point - if the speakers are all of the same type then they should be wired identically, but odds are he'll have two different pairs.

we know they should be but its not unknown for same brand even top end to be connected different.