4 Ohms or 8 Ohms

[cullpacket]

What's the differ in sound coming from the amp??

[buddyrich]

It's a long time since i studied this but here's a blind stab at it.

Ohms are a measure of the resistance encountered by the signal being sent to the speakers from the amp, or in other words it's a way of measuring the signal strength that will be sent to the voice coil of whatever loudspeakers you're using.

The ratings are used to ensure you dont mismatch components and damage them-too strong a signal from amp to speaker isnt a good idea as heat, volume and subsequent repair bills are generated.

As far as i can remember, both outputs should provide the same sound qualities so long as they're connected to the properly rated speaker. (Is amplitude different between the two? Christ i canna mind. Maybe?)

[dx100uk]

yep quality will be no diff
BUT you should not put a lower ohms value load [speaker] on to a terminal that states a greater value. [amp damage to O/P stage or valve.]

now unless you intend to parallel - join [red to red, black to black] more than 2 8 ohms speakers to one 4 ohms terminal, you will do no damage.

you can ofcourse put an 8 ohms speaker to a 4 ohm output, it will just be twice as loud [but ofcourse twice the wattage O/P so make sure the speaker is rated as that or more]

dx

[BigKev]

Impedances should always be matched for best efficiency.

If you aim to have the same speaker impedance as amp impedance output you will get the most watts, simply.
you can connect mismatched loads to your amp but its not good for the amp tubes or op transformer. and will eventually knacker either due to either heat or overvoltage.

Match them and need not worry.

As for 8 or 16 or 4 ohm speakers, theres "generally" no difference. certainly none you can hear. or anybody else will notice. the numbers are just there so that you can attach different setups of cabs to amps without damaging it. which is why a lot of amps have options of ohm on the back of them.

Transistor amps are different in that they can supply any impedance above its minimum impedance, e.g. a transistor (solid state) amp rated at 4 ohm can suit 4, 8 or 16 ohm loads.

Tell us what you are planning, its not as complicated as i make it out to be!!

[cullpacket]

I have is Unison Research S6 valve amp which has 4 or 8 ohms output and the speakers are Living Voice Auditoriums and Ecosse 4.45 Bi-Wire cables 2-4
configuration, Never put a hi-fi together before,
Cheers

[BigKev]

Right, thats a dear amp for a first timer eh!

I found the amp on the unison site, but it only says 33watts a channel, how many channels does it have?

If it has individual 4 to 8 ohm outputs for each circuit you should work out the impedance of each speaker circuit(channel) and match it to the output.

[cullpacket]

Bought it all second hand 1/4 of the price, the amp has 2 channels, I phoned up the guys that make the speakers and said they are 6 ohms

[BigKev]

So, did you not say there are two types of speakers?

are there two speaker cabinets a side or just one?

[dx100uk]

Bought it all second hand 1/4 of the price, the amp has 2 channels, I phoned up the guys that make the speakers and said they are 6 ohms

so you will thus use the 4 ohms terminals. as the 8 ohms would be overloaded if you put 6 ohms load on them

prob will make no diff, but might distort slightly.

dx

[Dynamic Sounds]

you can ofcourse put an 8 ohms speaker to a 4 ohm output, it will just be twice as loud [but ofcourse twice the wattage O/P so make sure the speaker is rated as that or more]

dx

That is incorrect. If an amp has a rating of X Watts at 4 Ohms, on an 8 Ohm speaker you will get as a rule of thumb 60 - 70% of the power, so will be about 1/2 to 2/3 as loud. (all to do with square roots and logrythms).

As Kev said as long as you go above the minimum impedence, but usually no more than 4 times it, the amp will work ok.

[dx100uk]

i was trying not to blind the op with too much science.

i have worked in tronics for over 40yrs.

dx