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Topic: How to match impedance+wattage between speakers/amps? Recommended amp? (Read 25394 times) previous topic - next topic
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How to match impedance+wattage between speakers/amps? Recommended amp?

Hello all at HydrogenAudio! This is my first post on these forums (and on any audio forum, as a matter of fact) since I'm quite new to the HiFi audio scene, and I've got a couple questions to ask.
First of all, regarding impedance. Two of the speakers that I am looking at for a new setup have an impedance of 6 Ohms. In parallel, I read that these speakers would need an amp which supports 3 Ohms of impedance, and in series, one with 12 Ohms (and perhaps also a preamp with these specs; I don't know). First of all, is all of this true? And second of all, do I run my speakers in parallel or series, and why?
Another question has to do with power; each of the speakers has a recommended power of "25W-100W", which (to me) is a very large spectrum. I read from an online source that an amp should have twice the recommended wattage of the speakers per channel. Does this mean that I should have an amp with 50wpc, or with 200wpc?
Another question; could any of you recommend a good amplifier that is relatively cheap (say, under $600) with the proper impedance and wattage for the speakers (B&W 685s or Wharfendale Diamond 10.2s)? (Edit: I realize now that there is a separate section for this; pardon me).
And finally, is there a way for me to choose a "Best Answer" on these forums in order for me to reward the posters for their hard work? I know that there is this option on some other forums, and I would certainly hope that it is available on this forum as well.
Thanks so much in advance for the help, and I'm sure that I'll be back soon enough with more questions.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #1 –
You don't run them in parallel or series. Each speaker connects to a channel on your amp. The specs show watts per channel into a given load. Unless I'm missing something?

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #2 –
Quote from: dannyboy2233 on
Hello all at HydrogenAudio! This is my first post on these forums (and on any audio forum, as a matter of fact) since I'm quite new to the HiFi audio scene, and I've got a couple questions to ask.
First of all, regarding impedance. Two of the speakers that I am looking at for a new setup have an impedance of 6 Ohms. In parallel, I read that these speakers would need an amp which supports 3 Ohms of impedance, and in series, one with 12 Ohms (and perhaps also a preamp with these specs; I don't know). First of all, is all of this true? And second of all, do I run my speakers in parallel or series, and why?


As another post says, each speaker is connected to its own amplifier inside the AVR. So the speakers are not connnected in series or parallel, and your question is moot.

Quote
Another question has to do with power; each of the speakers has a recommended power of "25W-100W", which (to me) is a very large spectrum. I read from an online source that an amp should have twice the recommended wattage of the speakers per channel. Does this mean that I should have an amp with 50wpc, or with 200wpc?


Power ratings of speakers tend to be soft. What 25w-100w means is what it actually says - the speaker will be satisfying for you with a power amp rated at from 25 watts to 100 watts. The book you read about amps having twice the recommended wattage of speakers per channel sounds to me like a book for live sound, not home audio.


Quote
Another question; could any of you recommend a good amplifier that is relatively cheap (say, under $600) with the proper impedance and wattage for the speakers (B&W 685s or Wharfendale Diamond 10.2s)? (Edit: I realize now that there is a separate section for this; pardon me).


There seem to be about 1,000 different A/V receivers (AVRs) on the market today. Just about all of them will be in some sense pleasing when used with conventional speakers. The last AVR I bought is a Denon. Its pretty good and I'm pretty sure it will work well with the speakers you are thinking about.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #3 –
Thank you so much for the reply! I did not realize that about my first question, and after looking back on my source, you are right once again about being live sound.
However, a majority of the amps that I have seen are 4 and 8 Ohm amps, and not six. It seems to me that having a 4 or 8 Ohm amp with 6 Ohm speakers can not only ruin the sound, but can also bust the speakers. Am I perhaps just looking in the wrong place?
Also, in terms of power, is there a certain side of the spectrum that I should go with? Is 50W or 100W going to be better sound, or is one going to be bad for the speakers?
Thanks so much!

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #4 –
If an amplifier is rated at 4 and 8 ohms then it will work with any impedance between those values. The power rating will be a little different at each impedance, but typically it will not vary that much over this range, and may even be higher at 6 ohms than at either 4 or 8.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #5 –
Quote from: dannyboy2233 on
Thank you so much for the reply! I did not realize that about my first question, and after looking back on my source, you are right once again about being live sound.
However, a majority of the amps that I have seen are 4 and 8 Ohm amps, and not six. It seems to me that having a 4 or 8 Ohm amp with 6 Ohm speakers can not only ruin the sound, but can also bust the speakers.


Not a chance. The ohms ratings of speakers is nominal, and actually varies by ratios on the order 3 to 6 to 1 over the audio range.

Quote
Am I perhaps just looking in the wrong place?


I don't think so. I think you may be confused and think that audio is brain surgery. It isn't. ;-)

Quote
Also, in terms of power, is there a certain side of the spectrum that I should go with? Is 50W or 100W going to be better sound, or is one going to be bad for the speakers?


The real question is how much power are you going to actually use when you are listening to music.  With typical speakers and a typical receiver, and at a typical listening distance your system will get plenty loud without audible distortion from the amplifier.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #6 –
Pardon me for misunderstanding, but I would be best off with a 4 Ohm amp or an 8 Ohm amp? I didn't really catch that.
And also, for the last thing you said, I was a bit confused; is "typical" supposed to refer to their wattage, or their impedance, or their performance overall? And with everything at "typical" level (since that is probably how it will be for me; mostly classical music played relatively quietly, and not much Metal/other loud music), what should my specs be? 50wpc? 100wpc?
Thanks so much once again!
 

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #7 –
To put this into better perspective, not accounting for transient peaks, most typical home listening is well below 1W.  The most dynamic material will require 20dB of headroom (a 100-fold increase in wattage).

Speaker sensitivity, room size, listening location and target SPL are the primary factors in determining how much power you need from your amp.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #8 –
Modern solid state amplifiers don't come in "4 ohm" and "8 ohm". They will all work quite well at either of these impedances as well as any impedance in between. They will also work with any impedance higher than 8 ohms, but will provide less power. They will even often work with impedances somewhat below 4 ohms, but you need to check the ratings in this case.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #9 –
Quote from: pdq on
Modern solid state amplifiers don't come in "4 ohm" and "8 ohm". They will all work quite well at either of these impedances as well as any impedance in between. They will also work with any impedance higher than 8 ohms, but will provide less power. They will even often work with impedances somewhat below 4 ohms, but you need to check the ratings in this case.

Ahhhh, okay. Thanks for clarifying that.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #10 –
Another thing; pardon all of my questions, but this is much more confusing than I thought.
Take, for example, the Rega Fono Mini Phono Preamp. This is supposed to take the signal from the turntable and amplify it to a line-level signal, correct? However, it has two line-level inputs; if this is supposed to convert into line-level, why would there be an input for that exact format?
Also, how would these be connected (in terms of specific wires)? I know the order in which they would be connected, but I don't know how all of the wires and cables work.
And another thing; how does one go about turning on their system? I know that for my home theater system, I have a universal remote which can turn everything (e.g. T.V., receiver, DVD-player) on at once, but is there something like this for a HiFi system?
Once again, thanks so much for your fantastic help.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #11 –
Quote
Pardon me for misunderstanding, but I would be best off with a 4 Ohm amp or an 8 Ohm amp? I didn't really catch that.
The amplifier rating is the minimum.*    If the amp is rated at 8 Ohms, you shouldn't connect 4 or 6 Ohm speakers.  However, you can connect 6 or 8 Ohm speakers to an amp rated at 4 Ohms.

Impedance/resistance means "resistance to current flow".  With a given voltage, you will get more current with less resistance (and more power).    With 4-Ohm speakers connected to an 8-Ohm amp (or two 8-Ohm speakers in parallel) you'll potentially get to much current and you can damage the amp.

Since we don't know how loud you listen, how efficient your speakers are, or what your acoustics are like, it's impossible to predict how much power yoy "need" and how "big" your speakers need to be.  Most modern amplifiers & receivers are rated at about 100W per channel (or more), and that's more than enough for most home listening situations (and it's enough power to damage most speakers).  There's nothing wrong with having more power than you need as long as you don't "go crazy" and burn-out your speakers.    If you want to "rattle the walls" or have loud parties, you need LOTS of power and big sppeakers with big woofers!

Quote
I read from an online source that an amp should have twice the recommended wattage of the speakers per channel.
It's actually twice the maximum rated power, not  twice the recommended power.  That's for live professional set-ups, or where you might be pushing the volume to the limits.  And it's only true if you can trust the speaker manufacturer's ratings.    The idea is that the average wattage for music is much less than than the peak wattage.    So, you can safely use an amp rated at twice the maximum speaker rating (and the speaker can handle the temporary peaks) as long as you are not driving the amp into distortion (which increases the average power). 

The recommendation is the opposite  for guitar amplifier applications where there is likely to be lots of distortion (the speaker should have twice the amplifier rating).    If you are using a full-range speaker system (with a tweeter) and you are driving the amp into severe distortion, your speaker should probably be rated for more than twice the amplifier power because tweeters can't take as much power as woofers.




* It's the rated load impedance, it has nothing to do with the amplifier's actual internal source impedance.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #12 –
Quote
Take, for example, the Rega Fono Mini Phono Preamp. This is supposed to take the signal from the turntable and amplify it to a line-level signal, correct? However, it has two line-level inputs; if this is supposed to convert into line-level, why would there be an input for that exact format?
No.  It has a pair of phono inputs and a pair of line-level outputs.  (Both with "RCA phono" jacks".)  The preamp outputs go to line level inputs on your receiver (AUX, Tape, CD, etc.).

NOTE - Many modern turntables have a built-in preamp and line-level outputs (especially the less expensive ones and turntables with USB connections).

Quote
And another thing; how does one go about turning on their system? I know that for my home theater system, I have a universal remote which can turn everything (e.g. T.V., receiver, DVD-player) on at once, but is there something like this for a HiFi system?
Sure, your universal remote will probably work with your receiver.    Of course, there will probably be functions that you can't access with the universal remote.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #13 –
Thanks for clearing that up; I'm not sure how I made such a drastic mistake in reading the article, but whatever
So to clear things up here: I could have a setup that goes from TT (Pro-Ject Debut Carbon) -> Phono Preamo (Rega Fono Mini) -> Amp with 200WPC (?), 4 Ohm impedance -> Speakers (B&W 685s, Wharfedale Diamond 10.2s)?
Note: All choices in products are not final; those are simply the ones that I have seen highest recommended/fit my price range.
As for the remote; my problem is that I don't want to use my current remote. This will be in a completely different room. I was simply using that as an example. I don't really want to spend another $150 on a universal remote, so are there any other options besides individually clicking on each device?
Thanks so much for your help!

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #14 –
Quote from: DVDdoug on
So you're saying that, for speakers with a rated wattage of 25W-100W and 6 Ohms of impedance, I'd be best off with a 200wpc, 4 Ohm amplifier?

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #15 –
Quote from: dannyboy2233 on
Thanks for clearing that up; I'm not sure how I made such a drastic mistake in reading the article, but whatever
So to clear things up here: I could have a setup that goes from TT (Pro-Ject Debut Carbon) -> Phono Preamo (Rega Fono Mini) -> Amp with 200WPC (?), 4 Ohm impedance -> Speakers (B&W 685s, Wharfedale Diamond 10.2s)?
Note: All choices in products are not final; those are simply the ones that I have seen highest recommended/fit my price range.
As for the remote; my problem is that I don't want to use my current remote. This will be in a completely different room. I was simply using that as an example. I don't really want to spend another $150 on a universal remote, so are there any other options besides individually clicking on each device?
Thanks so much for your help!

You're using vinyl, but turning on the components individually seems like extra work? For some reason that amuses me!

Anyway, 200wpc is almost certainly excessive. I'd bet that 100wpc is absolutely plenty, and you'd probably do just fine with 50wpc.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #16 –
Quote from: dannyboy2233 on
Quote from: DVDdoug on
So you're saying that, for speakers with a rated wattage of 25W-100W and 6 Ohms of impedance, I'd be best off with a 200wpc, 4 Ohm amplifier?


An amp that large would be a waste of money unless you wanted to play your speakers really loud.

Have you ever listened to an audio system playing with >85 dB average levels and >105 dB peaks, measured with a SPL meter or equivalent?

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #17 –
Quote from: dannyboy2233 on
Quote from: DVDdoug on
So you're saying that, for speakers with a rated wattage of 25W-100W and 6 Ohms of impedance, I'd be best off with a 200wpc, 4 Ohm amplifier?
Again, twice the amplifier power is for professional/Live/PA setups.  The idea is that it's safe to use up-to twice the speaker's rated power with music if you don't drive the amp into distortion.  You probably don't need that much power.  At home, it's generally safe to use an amplifier with even MORE power...  as long as you remain sober!    Probably 90% of the time a speaker is blown or damaged, there is alcohol involved...  The other 10% of the time it would be youth and immaturity...  Speakers tend to distort before they are damaged, so if you don't like listening to loud-distorted music you probably won't damage your speakers no matter how much amplifier power you have available. 

Also, note the difference between rated power and recommended power.  The top-end of the recommended power would be about twice the rated power.    Your "25-100W" speakers might be rated for 50W* (or less).      The low-end of the recommended power should tell you something about efficiency/sensitivity (how loud the speakers play with a given power level).  i.e. 25W should be enough for most listening situations.  But, there are no standards for minimum recommended power.   I've seen higher recommended minimum wattage for a more sensitive (more expensive) speaker from the same manufacturer.

Quote
TT (Pro-Ject Debut Carbon) -> Phono Preamo (Rega Fono Mini) -> Amp with 200WPC (?)...
I assume you also have some digital sources?  Personally, I am NOT a fan of vinyl.  Some people like the "sound of vinyl" and that's OK.  But, it's technically inferior to digital...  It's noisy, frequency response is "inconsistant" (depending on the phono cartridge and the recording), and sometimes distortion is audible.  And, most vinyl is old, worn-out and damaged.  Many (most?) older records didn't sound that good when they were new. 


* Power ratings for speakers are tricky.  The ratings for consumer/home speakers are essentially  worthless.    Pro speakers from reputable manufacturers are rated/tested according to IEC standards.    But even IEC ratings are tricky...  A tweeter rated for 100W is rated for the high-frequency part of a 100W musical (or music-like) signal.    So with a 100W amplifier and 100W high-frequency test-tones, you can easily fry the tweeter in a 100W speaker.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #18 –
Thanks so much for your help.
I'm not really someone who listens to music in excessive loudness; I would only get an amp that excessive for the sake of making sure that I don't blow my speakers. I'd rather spend a few extra bucks (relatively, of course) to get an amp with a higher wpc to make sure that my setup is safe from harm. However, if this is unnecessary, then I will gladly keep  my wallet a bit heavier.
So if I'm understanding you correctly, you're saying that an amp with 75wpc-100wpc (at 6 Ohms) will be more than enough for what I plan to do with the speakers (mostly normal listening level, occasionally slightly above normal)?
And yes, the digital sources would most likely come sometime soon, down the road.
Once again, thank you so much for your help

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #19 –
Quote from: Arnold B. Krueger on
Quote from: dannyboy2233 on
Quote from: DVDdoug on
So you're saying that, for speakers with a rated wattage of 25W-100W and 6 Ohms of impedance, I'd be best off with a 200wpc, 4 Ohm amplifier?


An amp that large would be a waste of money unless you wanted to play your speakers really loud.

Have you ever listened to an audio system playing with >85 dB average levels and >105 dB peaks, measured with a SPL meter or equivalent?

No, I haven't.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #20 –
Many people have and the consensus is usually that it is far louder than what they prefer.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #21 –
Quote from: dannyboy2233 on
I'm not really someone who listens to music in excessive loudness; I would only get an amp that excessive for the sake of making sure that I don't blow my speakers.


The idea that amps that are too small tend to blow or damage speakers more than large amps is an audiophile myth.

In the end it is excessive power that blows speakers. The best safeguard for speakers is an intelligent person operating the volume control. Much speaker damage is caused by people either abusing a speaker by using it for what it was never designed to do (such as using hi fi speakers for running a dance) or a system operator that is shall we say perceptually diminished, probably by some intoxicating substance including unfetter ego.

Common sense says that you can inadvertently apply too much power with a more powerful amplifier and common sense exactly predicts reality at this point.

There are actually two audiophile myths that one commonly hears related to amplifier power and this is one of them. The other one is that having reserve power means better sound quality at lower power levels.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #22 –
Quote from: Arnold B. Krueger on
The idea that amps that are too small tend to blow or damage speakers more than large amps is an audiophile myth.


The word "tend" has an awful lot of wiggle room, but do you have any external links which support this notion that it is simply a "myth", in actual real-world use, using (of course) the most prevalent form of music people who "blow up" speakers tend to use, namely electronic pop/rock [as opposed to acoustic folk/jazz/classical/etc.]?


Links which describe the mechanism by which a speaker "blows up" don't interest me, what I am asking you for is data to support your notion that the majority of blown speakers out there are due to large amps, kept within their safe operational range, driving speakers which simply can't take the kind of clean power those larger amps can put out.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #23 –
Woofers or tweeters?  Too much clean power can take out the former; I've seen it on multiple occasions.

Quote from: mzil on
what I am asking you for is data to support your notion that the majority of blown speakers out there are due to large amps [...] driving speakers which simply can't take the kind of clean power

That is not at all what Arnold said.

If anything, data must be presented to support the notion about which Arnold was skeptical.

How to match impedance+wattage between speakers/amps? Recommended amp?

Reply #24 –
Here's the, um, "myth" version:

http://www.jblpro.com/pub/technote/lowpower.pdf

"Too little amplifier power can produce too much

We occasionally hear of JBL owners who damage the high
frequency components of their loudspeaker systems using
amplifiers that are rated at less- rather than more- power
output than recommended. Understandably, they often find
It difficult to comprehend how such an amplifier can actually
burn out JBL components when they have been told, by our
dealers and in our literature, that JBL loudspeakers can
handle large amounts of power and will also deliver big sound
with relatively little Input power."

...

"However. if a small amplifier must be
overdriven to obtain the desired volume levels in a listening
room, thus generating high power and distortion levels. the
user would be better advised to purchase a larger amplifier
capable of producing the required power with negligible distortion"