Topic: What is the consequence of powering a 4 ohms speaker using an 8 ohms receiver?

[newbie pa rin]

I'm planning on getting a new speaker.
Problem is, it has 4ohms impedance.
I will hook this up to my HK 235 which has an 8 ohms impedance and a Bada power amp which has an 8ohms impedance as well.

Will be using this for about 2 - 4 hours per session.
Any long term effects on the speaker, amp and AVR?

[markcrenz]

I'm planning on getting a new speaker.
Problem is, it has 4ohms impedance.
I will hook this up to my HK 235 which has an 8 ohms impedance and a Bada power amp which has an 8ohms impedance as well.

Will be using this for about 2 - 4 hours per session.
Any long term effects on the speaker, amp and AVR?

di malayong mangyari ganito...

 

[praktikal]

Araguy!!!

[JojoD818]

Using 4 ohms will draw more current from your amp/avr. But if they were designed to handle the increase in current draw of the 4 ohms load then there won't be a problem.

However, even if they were designed to do so but your speakers impedance dips much much lower than 4 ohms then see picture above.

Look at the impedance curve of the 4 ohms speaker that you are about to purchase, if it has valleys all over the graph then I wouldn't risk it sir.

[JojoD818]

Teka, parang car amp yan nasa pic sa taas ah? And hindi yun power amp side ang nasunog but yun switching power supply! 

[markcrenz]

Teka, parang car amp yan nasa pic sa taas ah? And hindi yun power amp side ang nasunog but yun switching power supply! 

yan nakita kong picture sa google "burnt transistor" eh!  na-gets naman what i'm trying to point out. 

[JojoD818]

yan nakita kong picture sa google "burnt transistor" eh!  na-gets naman what i'm trying to point out. 

hahaha oo nga burnt talaga eh... yun amoy niyan mas matindi! 

[newbie pa rin]

Either I get another speaker or buy a new amp.
It seems most high end speakers has lower impedance.

Better audition another speaker or risk burning my avr/amp.

[cianzepol]

pano po malalaman kung pareho ng impedance yung receiver at speaker?

yung 608 po ba pareho impedance ng tsi 100,cs10 at ps110?

[markcrenz]

pano po malalaman kung pareho ng impedance yung receiver at speaker?

yung 608 po ba pareho impedance ng tsi 100,cs10 at ps110?

hindi magpapareho ang impedance ng amp/receiver at speakers, dapat bagay sila. nasa specs kung anong speaker impedance ang match sa amp.

[cianzepol]

nabasa  ko sa onkyo 608:

Speaker Impedance       6 ohms–16 ohms


yan po ba speakers na pwede sa kanya?

[muypogi]

I'm planning on getting a new speaker.
Problem is, it has 4ohms impedance.
I will hook this up to my HK 235 which has an 8 ohms impedance and a Bada power amp which has an 8ohms impedance as well.

Will be using this for about 2 - 4 hours per session.
Any long term effects on the speaker, amp and AVR?

You can use it on an 8 ohms receiver.  Yung nga lang, kulang sa power yung ibibgay ng receiver mo.  Also, if you play loud, baka ma-overload yung amp mo.

[newbie pa rin]

Using the HK and Bada power amp, volume level is -25 when using optical connection and -20 when using analog.
It seems the only solution is to risk it or buy a new receiver capable of 4 ohms impedance.

Is using a mono block also a solution since I needed a powerful amp to drive a 4 ohms speaker?

[JojoD818]

Using the HK and Bada power amp, volume level is -25 when using optical connection and -20 when using analog.
It seems the only solution is to risk it or buy a new receiver capable of 4 ohms impedance.

Is using a mono block also a solution since I needed a powerful amp to drive a 4 ohms speaker?

Sir hindi naman po kailangan ng powerful amp to drive 4 ohms load, ang kailangan po ay yun capable lang talaga. Kung hindi rated to drive 4 ohms load yun HK and Bada wag mo na risk sayang naman sir malaki talaga ang risk na masira siya.


Actually there is one trick (not on any book) to be able to use an amp not rated for 4 ohms for 4 ohms speakers. If the amp/avr has an AC input selector switch, select the highest AC input you can choose (i.e. 240V AC) then power the amp using 220V AC only. That way, you are actually reducing the secondary voltage available to the power amps gaining some amount of headroom for the output transistor's SOA (safe operating area).

DISCLAIMER: The 4 ohm/8 ohm switch you find on most high-end avr/amps actually switches the transformers secondary from low voltage (4 ohms) to high voltage (8 ohms). I have tried this many times successfully but with cheap gears only and experimental purposes. If ever you decide to try it, please don't be mad at me if you experience any problems.

[Onkyo606]

guess i got lucky that even at just 110 watts per channel, my receiver is capable of driving 4 ohms speaker.

[JojoD818]

guess i got lucky that even at just 110 watts per channel, my receiver is capable of driving 4 ohms speaker.

mahirap talaga mag negotiate ng low impedance loads because of the increase in current draw, at kasabay pa niyan ang pagtaas ng distortion. kaya nga napapanganga na lang ako sa mga nakikita ko amps na kaya mag drive down to 1-ohm...

[ATJr.]

depending on how loud you play, the ventillation around your amp, you may get away with it....

[pekspert]

Yes if you dont mind using your receiver to only a fraction of its full power (anyway its connected to a power amp) then you might get away with it. For additional protection put an additional electric/blower fan on your receiver.

[ment]

if the amp is not capable to drive 4ohms speakers then wag ninyo nang experimentuhin ..... either sell the speaker and get 8ohms speakers, or sell the amp ang get one with 4ohms capability .....

masusunug amp pag pinilit.....

[jon2]

if the amp is not capable to drive 4ohms speakers then wag ninyo nang experimentuhin ..... either sell the speaker and get 8ohms speakers, or sell the amp ang get one with 4ohms capability .....

masusunug amp pag pinilit.....

My speaker is polkaudio lsi7 it's 88db and 150 watts at 4 ohms,i'm using an old gear HK avr85 at 7db gain sa avr at -10 s volume mabibingi k n s lakas pag s music and ht .My avr is only 85 watts per channel and 90 watts dynamic but never n nasunog or ng clip, s loob ng 3 taon ko ng ginagamit.at n try ko ring gumamit ng entry level n avr, onkyo 503 to drive this speaker for 7 db gain at 40 s volume, napakalas n rin at never din n nasunog ung amp.just my 2 cents.

[jon2]

napansin ko lng medyo madaling mg init ung avr kapag nk large ung front speaker, nung inilagay ko s small hindi na mabilis mag init. Nakaka one movie n ako pero kung baga s tubig maligamgam lng ung init nung avr. nakakatulong din ung good ventilation ng a/v rack,ung s akin 6 3/4 inch.ung gap pwedeng mgkasya ung 2 avr n mgkapatong.d n kailangan ng blower fan dagdag ingay lng pag nakikinig k ng music

[ATJr.]

if the amp is not capable to drive 4ohms speakers then wag ninyo nang experimentuhin ..... either sell the speaker and get 8ohms speakers, or sell the amp ang get one with 4ohms capability .....

masusunug amp pag pinilit.....

i have said when i first joined here that the relationship between the amp and the speakers is a tenuous one, and is one subject that is easily the most misunderstood...

speaker impedance is not constant, it varies all over the place as frequencies varies....an 8 ohm speaker from one vendor can be 4 ohms by another ......

sensible use of equipment is the only way to avoid problems....

[markcrenz]

sensible use of equipment is the only way to avoid problems....

+1

problema lang sir tony pag napapasarap sa pakikinig usually napapalakas din ang patugtog, and that's when the dangerous currents flow. 

[Stagea]

Actually, mabait na load ang Polk LSi series speakers for "4 ohm" speakers. Hindi bumabagsak masyado ang impedance nila, at hindi rin masyado nagiging capacitive.

There are many "8 ohm" speakers around na mas bumabagsak pa ang impedance kesa sa LSi (with matching wild variations pa sa phase angle).

LSi9 Impedance Plot


Electrical Phase Plot


Notice that it only goes below 3 ohms below 70Hz, and is almost never capacitive above 40Hz (except for a very mild change in phase angle at 2kHz). If you run an HPF of 60-80Hz, the amp load may indeed be manageable.

[pekspert]

Ive done this before and nothing happened. Your receiver and/or amp has a built in circuit protector. It will clip if it gets way too hot. So if that happens, it means its having a hard time driving your speakers. But with an external amp to aid the internal amp of the receiver, it should be able to tolerate the power craving of your 4ohm speaker. If it cant your external amp will simply clip. You simply turn it off and let it rest for a couple of minutes. Then puede na ulit.

[newbie pa rin]

The HK avr will shutdown to protect itself.
I'm not sure about the Bada power amp connected to HK.
Will the avr also protect the power amp?

Any suggestion of an AVR that can drive a 4 ohms speaker without much problem.
TIA

[pekspert]

Im sure the Bada amp has a built in protector. The japanese amps (yamaha, kenwood etc) had that feature way back in the 80's. Nagaya na yan ng chinese .

Your avr will not help protect your power amp directly. In your setup, the 4ohm speakers will be connected to the power amp and not the receiver. So it is your power amp that will be getting the brunt of the power-hungry-speakers. Think of it as a 80/20 split or even 90/10 between your power amp and HK receiver. Like i said it is your power amp that will clip if it gets too hot. Your AVR will be unharmed.

[JojoD818]

Im sure the Bada amp has a built in protector. The japanese amps (yamaha, kenwood etc) had that feature way back in the 80's. Nagaya na yan ng chinese .

Your avr will not help protect your power amp directly. In your setup, the 4ohm speakers will be connected to the power amp and not the receiver. So it is your power amp that will be getting the brunt of the power-hungry-speakers. Think of it as a 80/20 split or even 90/10 between your power amp and HK receiver. Like i said it is your power amp that will clip if it gets too hot. Your AVR will be unharmed.

kung DC-200 yun Bada, wala po sir.

[pekspert]

kung DC-200 yun Bada, wala po sir.

Now thats a problem

Naka-toroidal transformer na sila and yet...

[JojoD818]

Now thats a problem

Naka-toroidal transformer na sila and yet...

There are actually two camps battling about power amp protection circuits, to protect or not to protect discussion is truly a headache to follow.

An engineer will say "at this day and age of electronics, an active amp output protection is a must", then another one will say "no protection please, protection circuits mess up the amplified signal and are prone to nasty false triggering".

To make matters worse, this is not limited to discrete power amps, even chip amps aka "gainclones" suffer from this never ending discussion. For example, National Semiconductor's Overture series power amps employ SPiKe (Self Peak Instantaneous Temperature (Ke) Protection) which gives design engineers sleepless nights or even nightmares.

Fwiw, most high current pro amps like QSC power amps donot employ output protection circuits as these truly can cause misfires and false triggering.