Matching Speakers with Amplifiers

The question is a bit vauge, it depends on the application.

Generally the speakers need to be rated to handle the maximum amplifier output plus a bit extra!

As a general rule the better the speaker quality the lower their efficiency...e.g. better quality sound but quieter.

The impedance off the speaker (or combination of speakers) should be matched to that recomended in the amplifier specification say typically 8ohm.

Lastly in most pubs, clubs, discos etc the sound level is too high and the speakers are driven into distortion.

Dunno if this helps...it should start the thread going, maybe some of the audio guys out there will be more help.

Thank you Mr. Del the cat.

You said this right that amplifire can drive speakers into distortion and even speakers can be blow out.... to save my speakers .... and making my question more exact...

I have Creative megaworks 5.1 speaker system which have inbuilt amplifire and power is satelite speaker is 50 watts rms each and sub wofer is 250 watts rms total is 500 watts rms.

Now the problem is inbuilt amplifire is going to die soon ..and we dont have service center from this company in my city. (mumbai, india) and out of warrenty also.

Now i want to use only speakers from this system and i will buy another Amplifire then what shall i see to match these speakers and wofer with the new amplifire....???

I mean i know watts of speakers .. but dont know ohms and impedance of speakers then will it be problem to choose amplfier....??

So friends please help me out ... and you can give me web site link on this topic, this will also great for me.

Thanks once again and good luck 2 u all.

Vinayak K. Salunkhe

What you can do is to open up your speaker box and check the labels on the speakers. Hopefully, the manufacturer didn't erase the figures there. They will usually say what impedance your speakers are.

Most commercial amplifiers are 8 ohms. A lot of car stereos are 4 ohms. The thing is, if you know what impedance your speakers are, it will be easier for the salesperson to help you (if he's technically competent, that is).

So get that screwdriver out and start checking. Good luck.

P.S.

Technically speaking, speakers boxes are called "speakers" while the speakers themselves are called "drivers".

Mr. hi. I think I can help you. You need to use an instrument to measure the impedance, like multimeter. When you get it you have to look for an amplifier with the same characterist, a mean if your speaker are 8 ohms, at least your amp have to hand that impedance or less. About power handly you need to decrease around 25% the amp.

Re: "As a general rule the better the speaker quality the lower their efficiency..."

S H A M E !!! For decades, Radio City music Hall was filled with the awe-inspiring volume and dynamic range of the LaScala version of Klipsch's fully horn-loaded speaker(s), the 2nd most efficient in the world. See: http://www.klipsch.com/ (...bringing back the Heritage Series...)

The Klipshorn, first built in 1940/41 still stands as THE longest production-run speaker in the world - http://www.klipsch.com/products/details/klipschorn.aspx 1W=105dB

My own set...http://members.cox.net/ndt-tom/LR/System01.jpg is over 20 years old, and still sounds like showroom new ~ whether playing a pianissimo intro for Sarah Brightman or hurling thunderbolts from Blue Oyster Cult, I have YET to hear anything that can compete!

Inefficient Speakers = LSSH .... (Loudspeaker-Space-Heater)

Paul W. Klipsch (Fellow, IEEE), wrote a series of papers (The Klipsch Audio Papers) which are most enlightening, if you can get your hands on a set. Just another "2-cents" worth, here..............

Yeh..maybe that's why I said generally..?

I was working in HI-Fi and component shops down in Soho (the real one not the USA one) at G.W Smith &Co (radio) ltd

and making horn loaded speakers from the Wireless World Hi -Fi book (now where has that book gone) way back 35 years ago when electronics used discrete components, and there was a cellar full off WD stuff wrapped in brown waxed paper under Lisle street.

Speakers?...yeh been there done that .

"generally" accepted... Soho_cool...!

Recollections of these? http://www.tnt-audio.com/casse/virtuoso_e.html / or http://www.beauhorn.com/pages/virtuoso.html

Some DIY's get pretty freaky: http://www.passdiy.com/pdf/KleinHorn.pdf

Personally (being happy with all 8 spkrs in the system) I look forward to the day that I can hunker-down and build some honest-to-goodness tube-feeders for the flankers (and enjoy some airy old classics)!

In addition to what others have already written:-

Purists will be horrified, but who needs very High Fi in a car anyway? But you can place 8 ohm speakers on an amp with a 4 ohm output, you just lose a little top end power, but never ever put 4 ohm speakers on an 8 ohm output amp!!!

You also need to know if you have some sort of cross-over for your speakers to buy the correct amp.

Why not check the specs for your old amp and just buy a new one with similar specs?

If a 100W/channel amp has an 8 ohm output can you place four 8 ohm speakers across it (in parallel) if you only drive them to 25 W ?

If you mean 4 identical speakers as opposed to bass, midrange, tweeters etc

You would wire them as 2 pairs. E.G (2 in series )wired in parallell with the other (2 in series). This still gives you 8 ohms load so speakers and amp are all happy.

Thank you very much friends.... I got the point after many days.... because of you all.

Now my final problem is. I have two sets of sound system, both have inbuilt amplifire and inbuilt amplifire is not working so all my 9 midrange drivers and two subwoffer r lying unused !!! both set of drivers r with different ohm n watt handling capacity like given below.

1) 4.1 system with 5 watts rms / 4 ohms and woffer is 15 watts with 4 ohms total power of 5.1 is 35 watts rms

2) 5.1 system with 50 watts rms / 8 ohms and woffer is 250 watts / 8 ohms

now i have 4 mid range drivers with 4 ohms and 5 mid range drivers with 8 ohms

1) How can i use all my 9 drivers with different ohm (4 of 4ohms n 5 of 8 ohms) on 8 ohms amplifire ???

2) Can i put 4 drivers of 4 ohms on one output channel of amplifire of 8 ohms ... so its heavy power can be used by 4 drivers of 4 ohms combinly ???

please advise me .... as i dont want to throw this drivers or kept useless ... or i want to use all drivers with different ohm on single amplifire without any harm and no bad quality of sound....?

Thanks friends...

Vinayak K. S.

just an idea,

you could try running the 5 8s from the direct lineout of you amp, the place the 4 4s in parallel, But place a 1/2 ohms resistor before the parallel connection and a 1 ohms resistor after each connection, effectively splitting up the total voltage to each speaker in half or by a factor 1:2 ... and finish the line out or circuit by connecting to neutral, or ground for DC.

if you have more than one lineout that you can run the smaller 4s from, then you may want to increase the recommended ohms in parallel circuit above, to restrict the power ratio proportional to what your speakers can handle, but keep the ratio of 1:2 i.e. if using 10 ohms front and 20 ohms in series parallel.

Hopefully, someone may advise on the expected db change from the voltage drop?

sorry, I got that wrong, and I shouldn't have even commented. I wont be commenting again. I'll leave it for those that know what they're talking about.

please excuse my error.

For a single room there is no problem of Voltage /power drop.

In utility service it is better to use 100/70V system.

Most of the PA Eqpt has this output(s).

Dear Friends,

Thank you once again. Now looking further.... i would like to ask you.....

1) If as per your suggestion if i use 4 ohms drivers on 8 ohms out in series n parallel then will it results in loss in sound power.. or quality ..?

2) I heard that if drivers are not matching then wrong driver can burn amplifire... is it possible...... if yes then how it can happen?? (low power handling drivers can get damage because of hi powered amplifire this i know )

Once again thanks to you all

VICKYX2007.

Connecting speakers in series/parallel combinations is fine, if each is within its power handling rating there should * be no loss of sound quality.

NOTE. Speakers must be connected the same way round (phase) e.g. one terminal is usually marked with a red spot or some such, these must be connected to the same side of the out put. This is to make sure the speaker cones are moving in the same direction.

If yo had two speakers connected wrongly one cone would be moving out while the other was moving in...this would give a loss of volume and distortion.

The amplifier can burn out if it is driving too low a load, as it will try and provide too much current and the output transistors/fets or whatever will get too hot.

e.g if it designed to drive 8 ohm and you connect 4 x 8ohm speakers in parallel this would be 2ohm and the amplifier would be overloaded...it would be trying to drive four times it's designed current and would probably blow an output fuse (assuming it has output fuses) or blow th output devices (transistors/fets I.C etc)

* This assumes they are mounted in a sensible enclosure. (note:- A car is not a sensible enclosure...people who fit high wattage sound systems in cars have more money than sense.)

One small point in your excellent posting, the "red" dots or similar are only good if the speakers are identical......otherwise they do not always mean the same, you have a 50/50 chance of it being correct. Even from the same manufacturer!

To be safe, a simple test with a 1.5 volt battery with a 10 ohm resistor in series will show the direction/polarity of each speaker, provided the speaker cone movement can be observed. If the movement is too severe for safety, then up the value of the resistance to say 50 Ohms or so.....

Mr. Del The Cat...

Thanks for the explanation.... you said

(The amplifier can burn out if it is driving too low a load, as it will try and provide too much current and the output transistors/fets or whatever will get too hot.) means if we put more drivers with less ohms then how amp will put more power into drivers then its own output power...??? ( need to clear funda of electronics for me... haha )

friends,

What will happen if we put very hi capacity driver means 12" woffer which can handle 1500 watts of power to a small power amplifire which can able to driver just 150 watts driver.... means heavy load and less powerfull amplifire....???

You all can solve my problems..... i m greatful to you all.....

Thanks a lot once agian...

Regards.

Vinayak.

Hmmm, There is a bit of a language barrier...

I think you are asking ..

Q. What happens if you connect 150w amplifier to 1500w speakers?

A. It is OK the speaker rating ihow much power it can handle safely... it doesn't mean it always consumes that much power. The speaker will only consume the power which is driven into it by the amplifier...

e.g. If a 100W speaker is connected to a 1W amplifier it will only be driven by 1 W and only consume 1W...If it is connected to a 0w amplifier! (no amplifer) it will consume nothing! (0W ! )

I hope this clarifies it!

Del the Cat..... Hi.

I think you r online now....

The amplifier can burn out if it is driving too low a load, as it will try and provide too much current and the output transistors/fets or whatever will get too hot.

In this context i thought that heavy load can also burn the amp..... ??

Thanks....

Vinayak.

High yes I'm on line....

It's the term 'heavy load' that is confusing you!

A heavy load is a low resitance..(high current). EG A 2ohm load is a heavy load for an amplifier designed to drive an 8 ohm output.

A 2 ohm speaker rated at 1000W is EXACTLY the same load as a 2ohm speaker rated at 20W ! The difference is obviously one can have more power pushed into it before burns out.

Don't let the speaker Wattage rating confuse you...that is just the amount of power it can handle before overheating/distortion. (If the power is pushed into it by the amplifier).

Regards

Del.

Mr. DEL THE CAT...

Can i understand that ....

Less Ohms means more output of sound ?? or Driver with high sound output has lower impedance.... can u explain me .... if you got time now... or later will do....

Thanks...

Vinayak.

Hmm. you are sort of right!

In general electronic terms less ohms would give more current which would give more power.

You need to know ohms law R=V/I ( R is Resistance (ohms) V is volts I = current (amps)

So if you amplifier gives out V volt then less R means more I (current)

Power is VxI so more I=more power.

However it's not quite that simple...you can't just reduce the ohms as you might blow up the amplifier!

The Amplifier is the start point It will have a maximum output power and a designed output load (usually 8 ohm...resistance and impedance are near enough the same).

You must use speakers of the right impedance (ohms) Whatever you do with the speakers you will not get more power out than the maximum amplifier power.

E.g.

!00 W amplifier.... you can put 1000w speakers on it but you still can not get more than 100 w out of the amplifier.

(Note some speakers are more efficient than others and will sound a bit louder.)

The output power of the amplifier is not necessarily linked to the output impedance.

So a high power amplifier could be 4, 8 ,or 16 ohm output..it depends on the design.

(Output power is VxI which works out the same as Vsquared/R so if you design an amplifier it is easier to use a higher voltage output (gives a nice big Vsquared) . the alternative is to use a low impedance but then you have high currents which are less easy to design with....so it can be done either way)

I'd suggest you read up on basic electronics and Hi Fi.

Have fun

Del (what time is it where you are? it's 7PM here)

I just googled a few different phrases...

'Speaker Impedance' gave loads of sites with sensible explanantions...try some of these..they may explain it better than me...

Del

Responding to #5 (especially), but also #22, and others as well;

Post #23 gives the best overall advice, because NONE have addressed the fact(s) that impedance is altogether different from resistance (which is what you measure with the ohmmeter portion of a multimeter, post5...), AND that unless you have some real "high-end" speakers that state at WHAT specific frequency their impedance is rated at, then you really don't know all that you need to know about them (for OPTIMAL matching). Typical (cone-type) speakers ("air-pumps") might be rated as an 8Ω 'load' ... but that typically means that THAT is the impedance AT a signal input frequency of 1000, 1500, or some other frequency at which they have measured and documented it (a performance parameter that they, the manufacturer, MIGHT not even be willing to divulge!).

So, even though a speaker in question is stated as exhibiting an impedance of 8Ω, the load (on the amplifier) could conceivably be as low as 2Ω or even 1Ω at some ridiculously low frequencies, such as you'll hear on lots of RapStreetUSA DJ CD's. And, depending on whether it's a single "full-range" driver or a multiple-driver ("hi-fi") speaker, it might exhibit even higher impedance at higher frequencies.

The questions in the original post do not have a simple cut-and-dried e-z response. "I want to know relation between Speakers and Amplifier." AND "How to match power of speakers and amplifier." The type of amplifier and its outputs (favoring current-preferential or voltage-preferential driver-elements) and the type of speakers being referenced (full range single driver, "3-way", electrostatic panel, horns vs. piezoelectric driver, etc) all come into play in achieving optimal matching characteristics ∞ which, of course, is the objective for achieving acoustical "nirvana" with one's system.

Post 16: are you absolutely certain about "4 x 8Ω speakers in parallel this would be 2Ω"? My feeble-fading mind still recalls some math. If not mistaken, that "formula" reverbs-of an often misquoted guideline....hmmm(?)

Yoda please help!

This isn't Yoda (he's in a different universe, or rather movie ).

I've worked with drivers (speakers, in layman's terms) and I've found, as you have, that impedance changes with frequency. What I've found, however, is that the eight ohm figure is a fairly constant value across the audible spectrum.

At 20 Hz, the impedance is eight ohms (more or less, depends on the quality and manufacturer). At the driver's resonant frequency, the impedance spikes (increases rapidly) somewhat. Again, how much it climbs varies from one driver to the next. Above the resonant frequency, the impedance rapidly returns to eight ohms. At around 1kHz, the impedance starts to increase gradually. The end impedance at 20kHz ((limit of my analyzer) also differs from one driver to the next.

Here's an illustration:

I've tested several high end drivers as well as cheap, low quality ones and they show the same shape.

For info, at lower frequencies where impedance drop to very low values, wire or coil resistance start to make a difference. At 0 Hz (pure DC), an 8 ohm driver coil has about 6 ohms of resistance.

In any case, there's no music information below 20Hz so there's no point in generating "sound" at those frequencies.

Finally, why would 4 pcs of 8 ohm speakers in parallel not equal 2 ohms?

Unless you misunderstood the statement, 4 × 8 ohm drivers in parallel does equal 2 ohms.

D'uh.

Of course I know all that impedance stuff... but I am trying to explain the basics in relatively simple terms, rather than confusing the poster with unnecessary complication.

I think it is you that is biting off more than they can chew if you don't understand what 4 x 8 ohm speakers in parallel will do.

Hi all friends,

Now I have general idea of 'the relation between drivers n amp' and come to know that it is not that easy as i expect ... hahaha

So i will come to the point once again....

I have connected 5.1 home theator (with inbuilt amp) to sound card (creative audigy-2 sound card) on my computer... and One subwoffer of Yamah Yst 305 model. But both inbuilt amplifire section is out of order. and now i have unused drivers of both the system and i have to use them with maximum efficiency.... Now total drivers i have are as below.

1) TWO WOOFER DRIVER -> TWO 8" SIZE WITH 6 OHMS AND OF 100 WATTS RMS EACH ( of YAMAHA yst 305 subwoffer)

2) ONE WOOFER DRIVER -> UNKNOWN OHMS 10" DRIVER SIZE AND OF 150 WATTS RMS (CREATIVE (CAMBRIDGE SOUND WORKS) - MEGAWORKS 5.1's Woofer

3) MIDRANGE +TWEETAR -> 5 DRIVERS WITH 8 OHMS WITH 70 WATTS RMS EACH

4) MIDRANGE +TWEETAR -> 4 DRIVERS WITH 4 OHMS WITH 10 WATTS RMS EACH

Q. 1) Means can I put above said 9 midrange drivers and three woffer drivers on one amplifire ??? You all suggest me what power amp shd i purchased and suggest me its output power and ohms ect... and in what way to connect the drivers to amp...??

q.2) Do I have need other amplifire to drive Woofers.... ?? or does woofer need another type of amplifire...??? mostly i have seen subwoffers comes with inbuilt amps. I want one common amplifire for midrangs and woffer.

We have very limited knowladgeable sales persons here in electronic shops if i ask this questions to them they simply say "NO" to my idea.... hahaha. they will suggest whole new system to me and my existing drivers will be unused .... so once again requesting you all to suggest me the best ....

THANKS DEAR FRIENDS...

Vinayak K. Salunkhe.

P.S.

Mr. Del the Cat i am from India, Mumbai... i am software engineear having lot of instrests in acoustics and have spend lot of money (against my income ...hahah) in my sound system and have enjoyed for 4 yrs now i have problem with them... and have to search for less expensive solution and trying to use existing drivers with some new amplifire....

Hi,

More questions from me first... The system you are trying to build is it stereo (2 channels) we are talking about? Or is it more? (maybe 4?). How much audio power do you really think you need? (Are you playing to a big room with 50 people or a domestic sized room with 6 people? What are their names ? (joke) )

I would suggest buying a digital multimeter, they are relatively cheap and it will help you a lot...you will be able to identify the impedance of unknown woofer and it will be a very useful tool.

I'm sure we can work out a way of connecting all the speakers.

But I would generally say it would be better if the units were all paired up...eg 2, or 4 identical woofers. 2,4,6 8 etc identical midrange/tweeters. It is then relatively easy to connect them up in a suitable configuration.

Del

My take on matching power and impedances:

Old advice is to match drivers and amplifiers in both power and impedance. I believe that still holds true.

Impedances:

Let's assume an 18W, 8 ohm driver being driven by an 18W amplifier.

Using our favorite Ohm's Law, we determine that our amplifier has a maximum current capacity of 1.5Amps [square-root of (18watts/8ohms)].

If we put a 4 ohm driver on this amplifier, the limit of 1.5 amps will be reached when the power output is at 9 watts (1.5amps² × 4ohms). So, your volume control is only at half setting but your amplifier's limit has already been reached. If you push the volume up some more, you'll eventually destroy your amplifier. Quite possibly, your 4 ohm speaker may also burn if the transistors short instead of open up.

About matching power to power:

If you have a 100W amplifier and a 50W driver, the driver could be damaged through excessive power if you push it too hard.

If you have a 50W amplifier and a 100W driver, the driver could still be damaged because the amplifier will start to clip as you try to push more power into the driver. This clipping is practically DC power being pushed into the driver which it is not designed to handle (plus the fact that it sounds awful).

If you intend to have a little quiet music in a small room, your drivers may be okay. If your kids (teenagers!) decide they'd want to have a dance party, you can kiss your drivers goodbye.

Friends, Del The Cat and Vulcan.... hi to you all...

Mr. Vulcan do you comes on cupidbay.com with same id ....?? i have seen your id somewhere ....

Thanks for the efforts taken by you all,as you are really educateing me on this topic...

Now please spend few mins more for me...... hope you will give me final solution on my problem....

Mr. Del the Cat... you said right, i have 250 sq feet music room and i use to listen alone... hahha... but some times my gruoup freinds used to be with me... and on some social functions i took whole my system with computer at our community hall and even out door terrace place also.... this system works fine even outdoor also... i mean enought loud in open....

I have hometheator system 5.1 and 4.1 both with "inbuilt amplifire" and have put both on sound card of my computer which have "5.1 out" with SNR 106 db (signal to noise ratio... you experts calls)

My Idea to use all drivers together is for that.... If i purchased hi output power amplifire then i have inbuilt then i have to purchase more strong new drivers for new amp ... instade of this new expance my idea is to use existing drivers with combination in pairs with adjustments of matching drivers forcefully..... by putting some registers n transfarmers to match the impedance and wattage capacity .....

Any how pls tell me what additional parts i have to put in my system like extra resisters or what ever.. I want to use my 3 woofers and 9 drivers with different ohms n watts .... i know the watts of speakers for sure and i will get info about impedance next time.... but we can take as exaple

eg....

1) New amplifire is with 5.1 out which haves 75 watts rms X 5 out on 8 ohms

2) two woofer drivers with 6 ohms , 100 watts rms

3) One woofer with say 4 ohms , 150 watts rms

4) 4 small drivers with 4 ohms and 20 watts rms

5) 5 drivers with with 8 ohms and 75 watts rms

Now friends ... match the given drivers with given amplifire ... you can suggest me any kind of extra attachment or part to put in between this system like register etc...

I can even purchase two different amplifire, one for 3 woffers and one for all 9 midrange drivers if you suggest me...??

Thanks n regards...

Vinayak K. Salunkhe

I've done it, it's not perfect but it's not bad. I'll send a sketch tonight if this description is too confusing.

Output 1. 6 ohm woofer in series with 4 ohm woofer (=10ohms which is ok)

Output 2. 6 ohm woofer in series with (2x8 ohm Midrange in parallel) (=10 ohm)

Output 3. (4 x 4 ohm small drivers in parallel) in series with 8 ohm midrange (=10 ohm)

Output 4. 8 ohm 75 W midrange

Output 5. 8 ohm 75 W midrange

I think this uses them all, check it yourself and try and work out the impedances to see that you agree.

Del

do you comes on cupidbay.com with same id?

No, I don't. Never heard of it in fact. In any case, Vulcans are supposed to be a non-emotional race. A place called Cupid doesn't seem to be a likely place to find them . _{So...someone else has the same handle eh?}

Back to the topic (now I don't have to check the "off topic" box, heh heh ).

I find this a bit funny. I'm planning to build a sound system for my house that uses only three speakers both for the TV and stereo system.

You, on the other hand, are planning to build a sound system with 12 speakers! Can't say I'd agree but then again, I've got an officemate who got a system to deliver up to 2000Wrms of pure, unadulterated music power. I hear he shakes up the neighbor's windows. Each to his own, I guess.

For me, you'd be better off marrying the 75W speakers with your 5.1 amplifier and buying new amplifiers for the other speakers.

Get an 8 ohm, 40W/channel amplifier and connect your 4 ohm, 20W speakers to them; two series-connected speakers per channel.

Get an 8 ohm, 130W/channel amplifier for your two woofers (100W). Why 130W? Since their impedance is 6 ohms, you'll need the extra power to handle the lower impedance.

If you still want to use the 150W woofer (I wouldn't), here's something you can do. Get a 150W (8 ohm), two channel amplifier. Connect the two channels together like so:

I've done this before and it works. You've got to make sure that the input signal going to both amplifiers is of the same signal (it would have to be mono) and at the same phase and level (volume). The two channels will share the current load and allow you to drive the 4 ohm speaker.

_{Now for the Use-at-your-own-risk-clause: This idea is presented only as a suggestion. The suggester will not take responsibility for damage arising from following his suggestion.}