Personally I wouldn't. It's likely to shut down if not cause other problems. Some 6 ohm speakers may dip down to 4 or worse, but what we don't know is how much do the 4ohm speakers in question dip. I think it's very risky, but someone else might chime with better info.
If the unit gets hot (or shuts down on heat) then no, the receiver will not do it. If you are looking for volume, then do not even bother, IMHO. Look for easy to drive speakers that sound good to you.
Cranking up a receiver that is unsuitable is also a good way to pop tweeters, so again, not IMO.
I wonder if you doubled up the car speakers - two pairs (4 individual 4ohm speakers), with each pair wired together in series - giving you two sets of two speakers, whether this would work, since theoretically it should get you up to a nominal 8 ohms. Not that a pair of 6.5" JVC car speakers X2 is going to sound any good.
M.R,it's cause I couldn't find the answer to my this question from Jan Vigne's answer.
But I couldn't understand one thing,avguide reviewer used Pioneer Sc-27 with Rx series(including Rx8) for the review?What about this?I think Pioneer Sc-27 is a 8ohm rated receiver,although I am not sure cause I don't understand much from spec lists,I just saw 8 ohm writing.
Some reviews should not be taken too seriously. I don't know the receiver or how it handles 4 ohm loads. However it just isn't advisable, though not necessarilly impossible.
Jack, you thanked me for the detailed response to your OP. If you didn't understand the reply, you should have said so and asked further questions.
The most important point of my response is that "four Ohms" doesn't tell you much. You need to know where that impedance point falls, how low does the impedance dip, how high does it rise and then you must also know how the electrical phase angle affects those values. You probably don't understand "electrical phase angle" but that's the other point to my response. By simply looking at a piece of paper with meaningless numbers on it you can't tell anything about the real world functioning of the component.
IMO the only numbers worth looking at are HxWxD plus weight, virtually every other "spec" you read is meaningless and is certainly so if you have no idea what that spec refers to, how it is measured or how it relates to other measurements.
While your receiver might be "6 Ohm rated" that too tells you nothing of value other than it doesn't care to be connected to anything that doesn't at least claim to be a "nominal" eight Ohm load. Your original thread stated you were looking for a "cheap" receiver. Cheap and capable of driving difficult loads do not go together.
That doesn't mean a "6 Ohm rated" receiver cannot drive a four Ohm speaker because all four Ohm speakers are different and some receiver manufacturers state their impedance warning to make certain their product isn't stupidly abused and they are expected to cover stupidity with their warranty.
The warning clearly states don't use less than a six Ohm speaker. Yet you ask if you can ignore the warning. The best answer is, only at your own peril and ultimate cost.
Most amplifiers can manage a four Ohm nominal load at low to moderate volumes or for short periods at high volumes. Most reveiwers have been doing this long enough to recognize signs of distress and to realize the limits of the system at which time they turn down the volume. Most people asking the questions you are asking do not recognize those same limits.
The cheaper the amplifier, the lower the volume constraints and the more likely you are to damage the amplifier - and possibly the speakers - if you do not know when to turn down the volume. If your budget is on the low end, then buying four Ohm speakers is highly unadvisable. If you go ahead and ignore the manufacturer's warnings, they can tell whether the amplifier has been abused when you bring it in for service.
The bottom line, I suppose, would be best stated as, no, there are no budget receivers that can drive four Ohm speakers if you want a warranty. If you don't care whether you blow up stuff, you will pay for whatever you damage. In that case you can buy - and keep on replacing - whatever you want until you learn to heed warnings.
If you still don't understand that response, you can ask more questions but you should not buy a cheap receiver to drive four Ohm speakers.
"Jan Vigne:The cheaper the amplifier, the lower the volume constraints and the more likely you are to damage the amplifier - and possibly the speakers "
Jan Vigne:My question is,if I buy more expensive but again 6 ohm rated amplifier,can it drive 4 ohm speakers?From your overall answer I understood like it can't.Also from your overall answer,I understood that a 8 ohm rated amplifier can't drive a 6 ohm speaker,right?
"I understood that a 8 ohm rated amplifier can't drive a 6 ohm speaker,right?"
Not really, there are no "8 Ohm rated" amplifiers when you get technical about it. Transistor amplifiers are at their best when they have a straight 8 Ohm load. Any reciever you buy will use transistors.
With few exceptions there are no straight 8 Ohm speakers and any speaker with more than one driver in it (a woofer and a tweeter) will probably be only a "nominal" (average) 8 Ohm speaker over most of its frequency response. It's average impedance can be higher or lower than 8 Ohms but it qualifies as an "8 Ohm speaker" because the manufacturer says it is. An 8 Ohm speaker can still be a difficult load since manufacturers get to say whatever they want about their products.
Make sense?
You're somewhat missing the basic element of the responses. The speaker's impedance curve and its electrical phase angle together determine just how difficult the load is for any amplifier.
Here are some examples of what I'm talking about taken from Stereophile editor John Atkinson's measurements section where his comments regarding how difficult or easy the speaker will likely be for any amplifier are addressed in the first section of the review.
The PSB floorstander dips just beneath 5 Ohms but its broadest impedance rests well above 8 Ohms and its inconsequential phase angle at the frequency where the impedance is lowest mitigates much of the difficulty of the low impedance itself. This is a low impedance speaker that won't stress most amplifiers. If you look, you'll see the solid "impedance" line hits its lowest point just at the same frequency where the dashed "phase" line rests at about 0 degrees. (The impedance is read from the left hand vertical, the phase from the right hand vertical and the frequency along the bottom line. The "phase" has both a + and - side to the measurement. The configuration of the crossover largely determines whether the impedance is high or low and whether the phase angle tends toward + or - going at any specific frequency.) So despite being a less than 6 Ohm speaker most amplifiers of moderate quality would have very little to complain about with this PSB. At 88dB electrical sensitivity the speaker is above average at playing loud with less than high wattage amplifiers. Though not perfect this is a good choice in speakers for any amplifier.
The Spendor is a small standmounted design that has lower than average electrical sensivity and will require more "watts" than most other speakers to get up to volume which means it could be considered difficult to drive to loud, room filling levels but, otherwise, its impedance remains above 10 Ohms for most of its frequency band. The phase angle is not high even when the impedance dips. Electrically, this speaker will mate well with any amplifier of any sort though its low sensitivity makes it a better match for amplifiers of good quality and not a common receiver. The Spendor is not difficult to drive but it will never play all that loud and it has a sonic pedigree that needs a good amplifier, it's far better suited for someone not interested in using it in a HT system or for a headbanger. The Spendor is ideal for classical, jazz and most blues but not for rap or hiphop.
The Klipsch presents rather high electrical sensitivity which means it will play loudly with only a few watts. That would seem to make this speaker a good choice for a cheap receiver in that you shouldn't have to push the amplifier very hard to get good volume levels. Unfortunately, this particular Klipsch also presents a 4 Ohm load and a -50 degree phase shift at 80Hz - just where a lot of musical energy exists in pop and rock and most modern music. This should be considered a difficult speaker for most amplifiers despite its ability to play loud with not much power.
Of the three speakers the Spendor would be the kindest to the amplifier as far as load is concerned but the most revealing of any cheap amplifier's quality. It will not satisfiy many listeners due to its volume constraints. The PSB would work well with most any receiver and would still be excellent when the amplification improved. The Klipsch would require a high current amplifier though not many watts, that's an uncommon pairing and typically not what you see from Klispch.
What's that tell you? Probably not much since you aren't in the market for any of these speakers and you need a cheap receiver.
If you buy a more expensive reciever, you should be looking for an amplifier that has high current delivery. When a speaker's impedance dips beneath six Ohms and/or when the phase angle is high (either + or - going) the amplifier must deliver more current (amperage) to adequately drive the speaker and avoid self destruction from overheating. Current (amperage) comes from a very stout power supply (the heavy part of the amplifier) and most receivers are not very good at supplying large amounts of current on demand.
If you are looking at a stereo receiver and not a HT system, your chances are better when looking for a high current amplifier. HT systems tend to attract attention by advertising high watts per channel and lots of features for low dollars. As a first rule, the lower the watts spec'd for the highest price will get you the best amplfiier. So, forget about how many watts you are buying and find the receiver with the highest current, the second general rule is this will quite often be the amplifier that weighs the most because the power supply is the heavy part of the amplifier and it produces current.
If you walk into a shop and ask for a high current receiver, most salespeople won't have a clue what you're talking about, certainly not at a big box like a Best Buy. You'd have better luck asking for the heaviest amplifier you can afford. If you shop the independent dealers in your area, you might have better luck since those dealers tend to know their product more thoroughly. Look in your Yellow pages for independent audio dealers.
Harman Kardon and Onkyo both tend to handle low impedance loads rather well given their price. HK typically has fewer features which is their trade off for buttons and knobs and bells and whistles against a better built amplifier. Either brand offers your best chance for driving any generic "four ohm" speaker.
You should understand by now that just saying the amplifier is four Ohm capable is not sufficient for just any four Ohm nominal speaker. Amplifiers with switches to allow lower impedance speakers limit current which is not desirable but it avoids other complications when cost is the deciding factor.
Speakers have an impedance and phase angle curve that wander around depending on frequency.
If your four Ohm speakers have a low impedance point that is balanced by a benign phase angle (like the PSB), they can be played by most amplifiers.
If the phase angle is high and the impedance is low (like the Klipsch), then you have a problematic speaker for any receiver.
If the speakers have a high electrical sensitivity (like the Klipsch), they don't require much power to go loud and the amplifier's job is a bit less daunting.
If the problematic impedance is in the midbass where "thump" resides in lots of musical styles (like the Klispch), the speaker is going to make life hard on any amplifier because it just simply requires large amounts of power to make bass compared to making high frequencies.
If the low impedance or high phase angle exist in the upper frequencies, not as much power is used to drive a tweeter when compared to a woofer.
Most tweeters never need more that 10-15 watts of power whereas most woofers will use everything your amplifier can deliver in most cases. Strangely though, tweeters burn out first when the amplifier is overstressed and distorted from driving the bass.
So there is no answer to your question other than suck it and see what comes out. Every speaker is different and neither cost nor size make any difference in how easy they are to drive. Any amplifier will prefer a simple load to a difficult one. A simple load is relatively high impedance throughout the frequency band and rather benign phase or benign phase when the impedance is low. Anything that strays from that becomes an increasingly difficult speaker for any amplifier.
The higher the sensitivity the better as a rule. The higher the sensitivity of the speaker, the less the amplifier has to work to play loud but the speaker might still give the amplifier fits.
Go back to my first response to your OP and I suggested you call the speaker manufacturer and get their advice on how difficult their speakers are to drive. Unfortunately, the trend in speakers is to build more and more difficult loads and make amplifiers cheaper and cheaper. Cerwin Vega and most of the Klipsch line of speakers are high sensitivity and not very difficult to drive - but a lot of people don't like their sound. If the speakers you have came from another system and you're trying to make them work, you're screwed. Not absolutely but you need to make plans to buy different speakers.
You'll stand a better chance of getting good information from an independent dealer. Any dealer should have either an audition or a return policy that allows you to try their amplifier with your speakers. Most small shops will encourage you to bring your speakers in to connect to their amplifier.
Those are pretty much the rules of the game. There is no one simple answer because there are no "standardized" components or speakers. You're buying a system and it behooves you to know a little about how systems work electrically. Most of what you need to know is not on a spec sheet. Most big box salespeople don't know enough to be helpful and don't generally care if you blow something up and bring it back since they'll have purchased their car stereo in a month or two and will be onto another job so they're seldom interested in learning enough about audio to be genuinely helpful and what they do know comes from car audio which has nothing to do with the rules of home audio.
If you already had the receiver and wanted four Ohm speakers, I'd tell you to not bother and make sure you bought speakers that were easier on any amplifier. As is, it sounds like you have four Ohm speakers and need an amplifier. Call the manufacturer and ask for their advice. If they tell you their speakers aren't that hard to drive, go from there. If these are speakers that came off a HTIB, they probably don't have sufficient frequency extension to be overly problematic for a good receiver but they need to be replaced.
That really is the best I can do with the information you've provided. It may sound like gobbledygook to you but those are the facts. Your questions have no simple answer.
Your first question in this thread asked about turning the volume up near maximum levels. I assume you mean you want to turn the system up beyond maximum levels. You will break most receivers. Have the salesperson explain to you how volume controls work - this is not as simple as it looks. If you want volume above all else, buy the speaker with the highest electrical sensitivity - assuming it is not a difficult load like the above mentioned Klipsch. The lower the sensitivity of the speakers, the harder the amplifier must work to play loud.
Is that why you now have speakers but no amplifier?
I am planning about buying B&W 685 or Monitor Audio Rx2 for now,but I will complete them into a 5.1 setup in the future.If I buy B&W 685 then I have to buy other speakers from B&W 600 series,and if I buy Monitor Audio Silver Rx2 I have to buy other speakers from Monitor Audio Silver Rx series.I love B&W brand and I want to buy it too strongly,but from what I understood from expert reviews,Rx8 is better than B&W 683.(I have been able to find only one expert review for Rx8,but a review for Rx6 was very similar)
B&W 685 is 8 ohm,Monitor Audio Rx2 is 6 ohm.If I choose Monitor Audio Rx2,then I will buy Monitor Audio Rx8 in the future,Rx8 which is 4 ohm.
I don't have a receiver for now,but I am going to buy a cheap receiver for now,and will have to change it to a more expensive receiver in the future,when I buy Rx8.
I don't have time today to explain this to someone who has decided to ignore every piece of advice given but, would someone please explain the problems with that thinking?
The intent of the advise to to avoid both for now, JD. Excuse me, the intent is that you re-assess your planning process.
Despite the advice that you have sought, you intend to continue with the purchase of a 'cheap' reciever and go from there with speakers that 'may' be marginal with such an amplifier.
My best suggestion is that you seek out the most affordable setup from a pawnshop, the used market or if need be, a HTIB for connectivity at the moment.
2 years from now, when new features are more advanced, connectivity improved, more HD sources available, then you may have had time to process the relationship between an amplifier and a load in a single circuit. Beyond what has already been offered as a basis for investigation and education, the rest is up to you to decide.
The most important thing I understood from "someone's" answers under this topic is,I have to understand answers.If I can't understand them exactly,I should not ask more,because someone may get angry and may blame me for ignoring his advices.I respect his knowledge,but I got very demorilized.
Nuck,I looked at the webpage link you gave.I think the problem is,I don't understand anything from electrical terms.I found the information too technical for me.
Jack, how old are you? I mean are you now a grown adult or still a youngster in high school? You get demoralized by not understanding my posts because I suggest you learn something? And when you get demoralized you decide it's best to simply ignore all of the advice given to you?
No one told you to stop asking questions, you have in fact been encouraged to ask more questions if you are having trouble understanding the posts.
I'm not trying to scold you, Jack, but you have posted here twice and when you don't understand the responses provided you simply decide to plunge ahead as if no advice had been given. Why'd you come here if you don't really want an honest answer?
Let's try this route; don't buy a cheap receiver. Period! End of response. Nothing more to say. Unless you really don't care about sound quality and you have very easy speakers to drive you are throwing your money away on a cheap receiver.
Neither of the speakers you are considering are easy to drive speakers but both are of sufficient quality to show you the problems that will arise should you connect them to a cheap amplifier. You will be back here or on another forum asking what new receiver to buy because your cheap receiver sounds not so good with your speakers that require a decent amplifier. And you'll be told to buy a higher quality amplifier. So, just skip the part where you do something dumb and buy the better amplifier now.
If you look through the archives of the forum, you will find the same question asked by numerous posters who tried to do exactly what you are going to do and they all got the same advice I'm giving you now.
If you want a high quality speaker, look at what the shop is using to demonstrate those speakers. That should just about be your benchmark for what you should consider to properly utilize the quality of the speakers. Anything far less than that benchmark will be shown as less than the benchmark once you play the system - that's the purpose of a high quality speaker, to show you what's coming in to it.
Neither speaker you are considering is well suited to turning it up to "near maximum" because both speakers have a tendency to stress the amplifier at loud volumes. If volume is your concern, these are not the speakers that are best suited to that purpose.
Here's my advice, buy a higher than you require amplifier/receiver now. Buy less speaker right now and when your funds adjust buy the better speaker and move the first set to the rears. IOW, put your money into the amplifier first and the speakers second. This will miminize the chances you damage both the speakers and the receiver. Any shop that sells either B&W or MA should be able to explain and demonstrate the logic of this approach. A system is only as strong as the weakest link in the chain, garbage in/garbage out. Both are wise suggestions for system building. Ignoring all the advice provided from those who have done this before is less than wise.
Also, don't depend on a reviewer's opinion regarding which speaker is "better". Either line, B&W or MA, is a high quality product as are numerous other lines you might consider - like the PSB which is a very easy load for any receiver based system - but getting your opinions of subjective quality from another person's subjective experience is never all that wise. You've been provided facts in this thread that are indisputable, those you can count on as not changing at the whim of a reviewer hearing a new product. Facts are facts and opinions are something entirely different. Decide which speakers you like and forget about whether a particular reviewer agreed.
Go to a good shop, listen and ask questions, Jack.
Going along with Jan's suggestion, the shops that sell MA, PSB and B&W should be able to suggest a receiver, for the purposes of HT that would best satisfy both your budget and your future plans, while doing the speakers the justice they deserve. So brands that build good value/cost receivers that should work with the speakers you've been considering are: As Jan suggested - Onkyo and HK would be a couple entry-level brands to consider. One rung up the ladder would be Cambridge Audio and NAD - both of which also provide great cost/value.
My first suggestion is get out there but leave your money and credit card s at home and listen to a few systems. Give it a couple days and then go back and listen to a short list. Then think about your budget once again and firm that up with the choices you've seen. Continue shopping in that budget and buy what ypleases your ears and meets your budget.
Cheers and all the best with it. The fun is just beginning.