Running your amp at 4 ohms

[Need4Sound]

Just wondering...........

How do you guys (and girls) feel running your amp at 4 ohm load?

I know most amps are designed for 4 ohm but is it not kinder to the amp to run at 8 ohm and perhaps use a 2nd amp if more speakers / subs are required?

Would anyone choose to use a budget second amp (Warrior, Kam, etc...) or run their existing amp harder (parallel connection @ 4 ohm)?

Is there any sound quality loss by running at 4 ohm?

Sorry if this has been asked before. :)

Richie D.
Need4Sound

[A1DL]

Just wondering...........

How do you guys (and girls) feel running your amp at 4 ohm load?

I know most amps are designed for 4 ohm but is it not kinder to the amp to run at 8 ohm and perhaps use a 2nd amp if more speakers / subs are required?

Would anyone choose to use a budget second amp (Warrior, Kam, etc...) or run their existing amp harder (parallel connection @ 4 ohm)?

Is there any sound quality loss by running at 4 ohm?

Sorry if this has been asked before. :)

Richie D.
Need4Sound

Most "professional power amplifiers" (using the term very loosely) will run at 4r without any problems, indeed the power ratings quoted by most manufacturers are generally at 4r because the higher number sounds sexier to their typical target market.

We regularly run our Macros down to 2r without any problems, even in the blazing sun without any additional forced cooling. However I wouldn't recommend doing that with a Kam/Warrior/Peavey or similar amp, unless of course you're going to pull it out of the rack and fry an egg on the case.

[ppentertainments]

We regularly run our Macros down to 2r without any problems, even in the blazing sun without any additional forced cooling. However I wouldn't recommend doing that with a Kam/Warrior/Peavey or similar amp, unless of course you're going to pull it out of the rack and fry an egg on the case.
What a coincedence. I am doing quite a prestigious horse show and turning on of christmas lights on friday. (will be on local news friday night). I have been asked for as many speakers as I have as they want the music and vocal announcements to fill the hall without being too loud. The hotel is where i regularly play so they know my kit. basically when all set up I will have 2 spare speakers. My warrior amp will already be running 4 speakers (down to 4r) do you think it would cope with a further 2 (will be running at 2r) bearing in mind it will be low volume for only about a 2 hour duration

[A1DL]

My warrior amp will already be running 4 speakers (down to 4r) do you think it would cope with a further 2 (will be running at 2r) bearing in mind it will be low volume for only about a 2 hour duration

If you are adding a further 2 No. 8r speakers (1 per side), the load will be 2.6r, not 2r

You will probably be OK at low volumes, but why not use another amplifier for the extra speakers?

Surely you're not doing a prestigious public event with just one amplifier and no backup? :confused:

[ppentertainments]

If you are adding a further 2 No. 8r speakers (1 per side), the load will be 2.6r, not 2r

You will probably be OK at low volumes, but why not use another amplifier for the extra speakers?

Surely you're not doing a prestigious public event with just one amplifier and no backup? :confused:

No. Using a total of 3 amps and also 1 as backup. Would like to keep 1 purely as backup 'just incase'. i only mentioned these other 2 speakers as they would be 'left over'. Not entirely sure exactly what I need until the arena seats are in place on Wednesday morning. They would just like as many speakers as possible in order to be able to hear the sound throughout without it being too loud.

[Excalibur]

If you are adding a further 2 No. 8r speakers (1 per side), the load will be 2.6r, not 2r

You will probably be OK at low volumes, but why not use another amplifier for the extra speakers?

Surely you're not doing a prestigious public event with just one amplifier and no backup? :confused:

Oh no, here we go with the impedance argument again.:( :( :(
We actually need to specify impedance and connection, as it's possible to run six cabs at 4ohms per side if they're 8ohm cabs, and two are subs, fitted with a crossover. If they're all full range in parallel, ( not an arrangement I'd recommend) then Tony is of course absolutely right.

[ppentertainments]

Just wondering...........

How do you guys (and girls) feel running your amp at 4 ohm load?

I know most amps are designed for 4 ohm but is it not kinder to the amp to run at 8 ohm and perhaps use a 2nd amp if more speakers / subs are required?

Would anyone choose to use a budget second amp (Warrior, Kam, etc...) or run their existing amp harder (parallel connection @ 4 ohm)?

Is there any sound quality loss by running at 4 ohm?

Sorry if this has been asked before. :)

Richie D.
Need4Sound

Sorry not to answer your question earlier.
I use Warrior amps and use them quite regularly with 4 speakers (4r load). To my ears I can't notice any loss of sound quality and have never encountered any problems. I have even ran 6 speakers(2 of them subs with crossovers) again with no problem at all. If using 4 speakers I prefer to use 1 amp and keep an amp as backup.

An argument to this would be to use 2 amps for 4 speakers, so if an amp did go down you still have 1 amp running 2 speakers. Personal Preference.

[A1DL]

If they're all full range in parallel, ( not an arrangement I'd recommend) then Tony is of course absolutely right.


I had assumed they were all full range and in parallel, Peter, given the application described by the OP.

Lots of amplifiers are only rated at 8r and 4r, and in these cases I agree it is best not to run lower than 4r.

We often run 8 full range cabs off a single VZ5K at outdoor events, only because it is a lot easier from a cabling perspective when running 200-300 metres of cable. This particular Crown is rated 2,500wrms/ch @ 2r.

[Excalibur]

I had assumed they were all full range and in parallel, Peter, given the application described by the OP..
You're probably right there Tony, now that I've read it again.



Lots of amplifiers are only rated at 8r and 4r, and in these cases I agree it is best not to run lower than 4r..
And apparently some of the 2r capable amps aren't really happy at that setting. Manufacturers being a bit optimistic in some cases.



We often run 8 full range cabs off a single VZ5K at outdoor events, only because it is a lot easier from a cabling perspective when running 200-300 metres of cable. This particular Crown is rated 2,500wrms/ch @ 2r.

I'm trying to think of a polite way to say "Flash Git! :p :p "

No, can't do it. :(

Flash Git :p

[nigelwright7557]

Just wondering...........

How do you guys (and girls) feel running your amp at 4 ohm load?

Richie D.
Need4Sound

It all depends on how much power the power supply can supply and also the output transistors and heatsinking and fans in the equipment.

If would be unwise to go below the manufacturers recommended ohms as only they know what the amps internals are specced at.

As an electronics engineer i have run my amps into 2 ohms or less regularly without any problems but I have huge heatsinks and dual fans in all my amps.

Once the power supply runs out of amps the volts will drop and you will probably just get loads of distortion.

[Creature]

on both my current rigs currently using 1 amp to 2 speakers (altho just brought some new bins for me larger rig.

the small rig is a little Kam 540 watt rms1U amp with 2 peavey xt500's speaker and is used in smaller venues and many upstatirs functions - this also has covered some bike rallies and often is used pretty much flat out for over 10 hours at a time.

the new larger rig im using a peavey CS3000 amp with 2 Peavey UL15s (altho just brought 2 UL18s bins not sure weather i will use the inbuilt passive crossover or another amp at this stage) again this setup often on teh go in excess of 10 hours (and last weekend did 16 hours pretty much at 90% all the time)

I am happy with both setups and dont use any forced cooling fans even in hot weather . I know peopel knock peavey and kam stuff, we all have a own personal choices of brands of equipment. Im lucky my local disco shop (some 36 miles away) I can take my kit there and play with there stuff for a slong as i want to make sure i get the quality of sound/equipment im after as well as helping to gain confidence in the new equipment.

I know both the Kam and Peavey amps I use are 4ohms and on reading the manuals they both dont recommend running at 2 watts for prolongued periods. and in fact is something i would not entertain.

[A1DL]

As an electronics engineer i have run my amps into 2 ohms or less regularly without any problems but I have huge heatsinks and dual fans in all my amps.

Makes/models, Nigel?

The Class D Crown I-Techs are specced down to 1R, and certainly don't blink at 1.3R...KOKO run 3 No. SRX728s on front fills off a single I-8000. Slightly underpowered on paper but it's got some welly.

[Solitaire Events Ltd]

Makes/models, Nigel?


Nigelmark 1

Has he not mentioned that he's an electronics engineer and makes his own?

I'm sure I read it somewhere? :sj:

[nigelwright7557]

Makes/models, Nigel?

The Class D Crown I-Techs are specced down to 1R, and certainly don't blink at 1.3R...KOKO run 3 No. SRX728s on front fills off a single I-8000. Slightly underpowered on paper but it's got some welly.

They are my own designs.

Multiple MOSFET output stage , huge heatsinks and dual fans in a PC case.

[A1DL]

I know both the Kam and Peavey amps I use are 4ohms and on reading the manuals they both dont recommend running at 2 watts for prolongued periods. and in fact is something i would not entertain.

Absolutely. Keep the output of Kam/Peavey amps less than 2 watts at all times to minimise the aural displeasure sustained by all but those very close to the speakers :cool:

[Tony Scott]

Absolutely. Keep the output of Kam/Peavey amps less than 2 watts at all times to minimise the aural displeasure sustained by all but those very close to the speakers :cool:


:lol:

[Need4Sound]

Thanks for the feedback guys. From what I'm reading it seems like 4 ohms is not a problem at all.

Leading me to my next question..............

I have a pair of 15" Yamaha speakers which I'm so far really happy with. However in the not to distant future I'd like to add another set of speakers, should I be looking at a couple of subs or another set of full range? I'm looking to have that bit more capacity for bigger venues / larger crowds.

Sorry if this is going a bit off topic. :D

Richie D
Need4Sound.

[Excalibur]

Thanks for the feedback guys. From what I'm reading it seems like 4 ohms is not a problem at all.

Leading me to my next question..............

I have a pair of 15" Yamaha speakers which I'm so far really happy with. However in the not to distant future I'd like to add another set of speakers, should I be looking at a couple of subs or another set of full range? I'm looking to have that bit more capacity for bigger venues / larger crowds.

Sorry if this is going a bit off topic. :D

Richie D
Need4Sound.
That all depends on what you want to achieve.

Option1). Louder. Assuming the cabs are 8ohms, get an identical pair. More drivers to move air, more power, it's all good news. If you get a different pair, you may find that one pair seem to sound different. That may be a good thing, I regularly do this, but I know what I'm trying to achieve, and what it will sound like.

Option2). More bass, and possibly a little more volume, certainly better sound. Get Subs, run the tops from the built in crossover.

Option3) As above, only more so. Subs, active crossover, second amp. Total control of sound, volume and clarity.

[nigelwright7557]

We often run 8 full range cabs off a single VZ5K at outdoor events, only because it is a lot easier from a cabling perspective when running 200-300 metres of cable.


You are probably dropping quite a bit of resistance along that sort of length of cable.

I have done some research into cables and their resistance.
Its amazing how much one piece of wire from one source is different to another. If using long speaker leads a good quality wire is essential to get peak performance.

[A1DL]

You are probably dropping quite a bit of resistance along that sort of length of cable.

I have done some research into cables and their resistance.
Its amazing how much one piece of wire from one source is different to another. If using long speaker leads a good quality wire is essential to get peak performance.

Absolutely - we only use Vandamme and Klotz signal and speaker cables for our inhouse operations.

[Andy Westcott]

Yes - with long speaker cable runs you need to either use very heavy cables with a large cross sectional area of copper, or run higher impedance speaker combinations.

The latter reduces the current requirement therefore also the resistive losses in the cable. If you can run into 16 ohms then so much the better, and you can boost the power available into that kind of impedance by bridging a pair of amps.

[leighinstoke]

Well, I run my Behringer into my Peavey Tops and Bins and it's at 4 ohms and happily running at an acceptable temperature.

[nigelwright7557]

Well, I run my Behringer into my Peavey Tops and Bins and it's at 4 ohms and happily running at an acceptable temperature.

Did you know a silicon transistor will run at upto 150 degrees C before dying ?

[Corabar Steve]

& more to the point, did you care?

[Andy Westcott]

Did you know a silicon transistor will run at upto 150 degrees C before dying ?

Ah but Nigel - that's the maximum permissable junction temperature, at which the dissipation must be zero.

Allowing for thermal gradients the heatsink must run rather cooler than that.

I know you knew that, but hey - let's confuse the masses, eh?! :)

[Corabar Steve]

Ah but Nigel - that's the maximum permissable junction temperature, at which the dissipation must be zero.

Allowing for thermal gradients the heatsink must run rather cooler than that.

I know you knew that, but hey - let's confuse the masses, eh?! :)

See post #24 :sj: