AMP to drive 4 Ohm speakers

 

Anonymous
I need an amp to drive the Axiom M80ti speaker. I'm looking for stereo only of course, and must be sub $1000 price point. I have looked at NAD, Adcom, B&K. I've heard the NAD C270 but not with my speakers. The reason I'm in this pickle is my HK 525 will not drive 4 ohm speakers. Opinions welcomed...
 

whiteusmc75
If you dont mind having a A/V receiver, the NAD T742, T752 and T762, would power the Axiom 4 ohm speakers. In fact if you go to Elegant Audio Video you can find the top NAD for $1050. Im looking to get the M80 system, do you know much about the Axioms, Im torn between them and Polk Audio LSi series
 

Anonymous
Yep, I'm familiar with the NAD recievers but as I said before, I have the HK525 already and it's less than a month old. I like the reciever but not able to handle 4 ohm speakers. I did some research on the M80 and I think it's a great speaker. A bit bright but that can be changed if needed with a replacement capacitor from Axiom. The thing I was after is a mountain of volume from these speakers. I have a large room and these speakers will be able to fill it nicely. The M80 is also easy to drive (efficient) with a modestly powered amp. I'm looking for about 200 watts per channel(at least) on a new amp.
 

G-Man
So you want 2 channels of stereo amplification with at least 200 watts per channel to hook into your HK receiver? If so---a great way to go is with the Outlaw Audio Monoblocks which crank out 200 watts into 8 ohms and 300 watts into 4 ohms. They cost $299 each. You buy two of them and you will have a huge amount of clean and discrete power all for $600 for the pair. And if you get more speakers you can always add additional modules. You can put them next to each other on the equipment rack, or you can do what a lot of audiophiles do----put them behind each tower speaker and if they are by the walls you won't even see them. This way you hardly use any speaker wire, but you need longer interconnects.

They are great and even useful for people that don't have amplified subwoofers.

These are great remedies for people that want more power but like their receiver.
 

Hawk
You have two good alternatives for separate amplification for 4 ohm speakers already identified. I really like the NAD (available from DMC for $420). I also like the Outlaw monoblocks. Both the NAD and the Outlaw are excellent choices. Now I will add a third idea.

Check out the Parasound Halo A23 amp. It is two channel--125 watts into 8 ohms, 200 watts per cahnnel into 4 ohms. It is THX certified, if that matters to you and it is a really nice sounding amp. Available from Audio Advisor for $850, but I know my local Parasound dealer will discount it a bit, so maybe your local dealer will too.
 

G-Man
I agree with Hawk. All of these are fine and powerful amps. That said, I have rarely liked the build quality of Parasound amps and pre-amps that I have opened up---but I doubt that has anything to do with the performance. I guess I shouldn't expect Bryston impeccable build quality at this price range:-)

The Outlaws are about 3 db's more powerful than the NAD and have a better S/N ratio, but I am confident all of this is far away from human audiblity. A lot of these issues are pride of ownership issues and acknowledging that the engineer did a good job in circuitry topography and design choice.

You can return the Outlaws within 30 days if you aren't happy and they have a 5 year warranty as opposed to the 2 year warranty on the NAD. But amps that will screw up usually do it in short order, so that shouldn't be too much of an issue either.

The NAD and the Outlaw both have a standy mode, so you don't have to turn them off, unless you are going away for a long time or you are worried about a thunderstorm. It is nice to have an amp turn itself on when it receives a signal. It is even a better feature in a subwoofer.

Just make sure if you buy the NAD at $420 that the warranty is honored by NAD.
 

Anonymous
Thanks to all.One question though, what is DMC? A website?
 

Hawk
Sorry to use shorthand, Anonymous. DMC is short for DMC Electronics, found at www.dmc-electronics.com.
 

Dsmith
I am surprised to hear your H/K receiver will not drive the Axioms; my experience with H/K receivers (AVR20II; AVR310; AVR520) is they have no trouble at all with 4 ohm speakers. In fact, my Digital Phase speakers are 4 ohm and I first used a AVR20II and they sounded great. If H/K has reduced current capability in the X25 line it is disappointing to hear. Is your judgment of the AVR525 current capability based on listening or use of the receiver? Or does its specs say not to use with 4 ohm speakers?

Dsmith
 

G-Man
I must admit I am suprised too. It is hard to believe that a healthy HK AVR525 would have any problems driving the Axiom speakers, unless the speaker wires are very thin and travelling a very long distance, something is wrong with a speaker, or you like listening at over 90 db's a lot.

Maybe all of the above :-)
 

Hawk
Over the past year, I have read a number of posts from people who found their receiver could not handle a 4 ohm load. A couple of months ago, I read a post from someone who complained about this very thing (4 ohm speakers with a H/K receiver), so I checked it myself. I was very surprised to see the back of the H/K receivers, in bold letters, say 8 ohm speakers only. Now, I thought H/Ks were supposed to have a great, beefy power supply, but apparently a 4 ohm load is still outside its operating paramenters. So I was a bit surprised, myself.

Now, a few years back, I had a buddy who tried to run 4 ohm speakers when the back of his receiver said 8 ohms only. When the amp developed problems, the dealer, with support from the manufacturer, disavowed the warranty because my buddy had "abused" the receiver and thus voided the warranty. Their basis was the fact that the 8 ohms only language was not only in the owners manual, but on the back of the receiver. Now, I am not saying H/K would do this, but other manufacturers have.
 

Dsmith
Hawk, my AVR520 has "(8 ohm)" beneath the speaker binding posts, but does not say "8 ohm speakers only." It may be that trying to shoehorn in 7 channels instead of five required a less beefy power supply, and if so H/K should be criticized for it. Still, I would be extremely surprised if H/K would ever try to weasel out of a warranty claim if you use 4 ohm speakers. And if you cross over at 80 Hz per THX specs I doubt if you will have a problem, especially if the Axioms are 90dB or better in sensitivity.

BTW, can you name the brand that denied the claim by saying use of 4 ohm speakers voided the warranty? I would like to know so I can avoid them like the plague. I think others would like to know also. Even if a receiver has a problem with 4 ohm speakers it should have protective circuitry that just shuts it down temporarily until the load is gone and then re-start.

Dsmith
 

Anonymous
Yes, the specs are 8 ohms only per the manual. So I took it at their word. No 4 ohm speakers. I have not tried the M80s on the HK for fear of something might break.
 

whiteusmc75
How would the receiver manufacturer even know if the receiver is blown due to using the 4 ohm speakers, and thus voiding your warranty??
 

Are those valid for my two DALI 606 speakers? I'm also looking for an integrated amplifier to drive my 4-ohm-DALI's. A second-hand dealer suggested me a HAfler 120. Should I go for it?
 

are there anyone who had experiments on DALI 606 speaker sytems? please write me about them to yozcan@yahoo.com
 

Dsmith
The impedance of the speaker is only part of the equation to consider, and even then remember that impedance varies with frequency; most speakers drop to lowest impedance in the bass region. So for HT, crossing over to a sub at 80 Hz will relieve the amp of most of that low impedance. The other thing to consider is how sensitive is the speaker. Speakers rated for sensitivity at 90 DB and above are generally not a difficult load for any receiver, unless they are below 4 ohm at most frequencies. My 4 ohm Digital Phase 2.1 floorstanding speakers were driven just fine for a couple of years by a H/K AVR20II rated at 55 X 2 in stereo @ 8 ohms. H/K has always been known for their relatively high current capable receivers, but as they went from 5 to 7 channels something had to give and it may be the current capability has diminished.

Anyway, since the 525 has preouts on all channels you can get the Signature 2.1 (100 X 5) amp that is very strong into 4 ohms for $688 at the H/K outlet store (harmanaudio.com) under "specials." For sure it will drive the Axioms with ease. The amp is refurbished, but my experience with H/K refurbs has been problem free and it still gets the full two year warranty.

Dsmith
 

Anonymous
I have run my M80ti's (4 ohm), and QS8's (6 ohm) on both a AVR55 and AVR525 at well over 90db without a hiccup. Check with HK, they will tell you 4 ohms is fine...

http://www.harmankardon.com/faq/showFaqanswer.asp?faqId=233

(The 525 is no specifically listed as the FAQ has not been updated. Call...I did).
 

I have just purchased about three months ago a NAD T742 and it clearly states 8ohm min on the back of the reciever. This is a shame because there are 4 ohm speakers i would like to purchase by Axiom but im not going to take the chance on blowing my reciever.Also if anyone can help me on this it would be appriciated.I also would like to by a amp, i asked the dealer i recieved my NAD from if it has a preout for future amps for more power he said yes but im not sure can someone give me advise on this avr,thank you.
 

Hawk
Wes:

Your dealer is correct--the T 742 has preouts for all channels (5.1).
 

Hawk:

Question: Should any discussion about improving ones system begin with speakers - 4/8 ohm aside?

Current system is best discribed as odds & ends.

jbl s-38's, s-36's / Considering Axiom, Vandersteen and others.

Sansui 771 reciever / The Nakamichi re-10 is next for stereo set-up.

Also, considering A/V for the future, but would like to do it well from the start.

Thenks!
 

Hawk
Terrance:

No, I would never suggest that you should always start with the speakers. In your case, I would suggest you start with your receiver as I believe your Sansui is a stereo receiver and you have an interest in establishing a good HT system, so you will need an A/V receiver. Therefore, I would start with the receiver as that is the platform from which you would build your system.

Now, having said that, I also think you want to shop for your new speakers so that you have an idea of what you need from your receiver and to provide you with a road map for future expansion. That will help you prevent having a system described as "odds & ends."
 

shaun6142
This is a replied email I got from a HK rep about running 4 ohm LSi Polks with the HK AVR7200, hope it helps.

"The power ratings seem a bit thin,
and they don't show any power ratings into anything other than 8 ohms. HK
has a history of under-rating their components power values. Believe me,
that's not the norm. The 7200 is rated at 100 x 7 channels, but is really
about 140 x 7 channels. 140w is the measured value just prior to clipping.
The high current capacity of this unit is the real kicker here. To answer
your question I would say that YES the HK unit will push those Polks---and
damn well too. The HK 325 and 525 units will too. Now, having said that
let's keep a couple things in mind. HK would probably tell you that all
their units are not meant to work into anything other than an 8 ohm load.
You can probably guess why. A prodigious amount of heat will be generated
while those Polks are pumping. HK doesn't want anyone burning the units up.
Your average consumer (who might not consider the impact of the 4 ohm load)
would run their AVRs to shutdown within no time. The 7200 has massive
heatsinks...I mean massive. There is also an internal fan, but I haven't
heard it come on yet and I've cranked this thing. If you were to run a pair
of those Polks hard with the 7200 you'd be fine."
 

Hawk:

Thanks for your timely response. AV recievers are new to me, and it has always been my desire to have a stereo system that can reproduce truly natural sound for jazz, r&b and rock/jazz fusion, which makes up 80% of my stuff. That said, is there a particular reciever that really can accomplish both stereo and AV functions accurately.
 

Hawk
Terrance:

I also use my AV receiver for a lot of music listening, which is not true for many people. For budgets below $1K, ther are only two brands that I recommend--NAD and Marantz. NAD is the best, but the Marantz 7300 is competitive.

What is your budget and what is your room size?
 

Fortunately, I'm in no hurry for av and the receiver budget will not exceed $700. I am willing to make all kinds of rationalizations about money spent on speakers to my wife however. My listening area is a finished basement w/carpet, paneling, and unfortunately a 6' 1/2 drop ceiling. It is approx. 30x20 and, other than the wood paneling, has very little reflective material to speak of.
 

hot rod
for all wondering about powering 4ohm speakers with an 8ohm specific amp.... i have a pair of 4ohm american acustics DS1212's that arent going anywhere.im running an HK325 with the worry of over heating so i recently purchesed an HKpa2000 to take the load instead.WISH ME LUCK!!!....will stay in touch.
 

Jerry
Every single amp I have seen built in the last 30 years is perfectly capable of driving 4 ohm speakers. There may be some that I have not seen that are not, but all your late model ones can, and if they say they can't, run, run as fast as you can.
 

G-Man
I have posted this before when I e-mailed Axiom about the 80 t's.

"Hello Greg,

The H/K AVR525 will drive the M80tis with ease. In fact, H/K and Denon are the only receiver brands that I recommend for the 4-ohm M80s (other brands either shut down, overheat and shut down, or limit current output severely into 4-0hm loads).

I use the H/K AVR525 and it drives my M80s and M22ti's with no problem. Ignore the warning on the back (Use 8-ohm Speakers). The H/K amps are stable and robust into lower impedances.

Thanks for your interest in Axiom!

Cordially,

Alan Lofft
Axiom Resident Expert

By the way, Alan Lofft has worked with some of the loudspeaker engineering greats, such as Floyd Toole and others from the Nationl Research Council in Canada--which is responsible for the birthing of Energy, Paradigm, PSB, etc.

He even has some articles printed on the ecoustics sign-on page.
 

Unregistered guest
Is there anything one can do to his 4 ohm speakers to make them 8 ohm. I have a nice piar of Infinity studio
monitors that are 4 ohm. My problem is my amp is 8 ohm.
Woe is me. Please email me.
 

Unregistered guest
can a technics sceh 790 hi fi amp seperate run 4 ohm speakers like jbl sf 25 or peavey hisys 2 rx? the reason i ask is that the manual shows 8 and 6 ohms but not 4 ohms? would the amp blow up or could it take 4 ohms speakers?

any advice would be grateful!
 

Unregistered guest
I have an old Marantz Stereo Receiver and 4 Braun L-710 speakers (4ohm). I've had these since 1970. I had to wire the speakers in series to prevent a loud clacking noise. They have worked very well ever since.
Last week the receiver lost the right channel in stereo but it still works in mono. I have no idea what the repair cost would be so I'm looking into replacing the receiver but keeping the speakers.
Should I stick with a stereo receiver or go with a home video receiver? Should I replace the speakers? I'd like to stick with Marantz (6300 etc) and keep the price under $600.00. You can tell that I haven't kept up with modern audio trends (my last purchase was 1970)so I need all the help and suggestions that I can get.
 

Unregistered guest
What causes a thumping sound from my sub when I switch inputs or power down?
 

swampcat
Unregistered guest
My harmon kardon powers 4 ohm speakers. Has 2 ohm rating as well . Its 20 years old though!!! different world then.

Adcom will power 2 ohm loads with no problem.
 

Unregistered guest
Okay,the discussion on 4 ohm speakers is very informative.At a garage sale I impulsively bought a pair of Bose 501 series II floor standing 4 ohm speakers. Did I waste $40.00? What amp/receiver should I buy under $1000.00 to power these? Does anyone have experience with the quality of sound of these speakers? What should I expect?
 

swampcat
Unregistered guest
Is the 4ohms a problem now a days? What happened. My intigrated harmon kardon drives 4 ohms no problem and rated to do so and power out put increases, my adcoms the same. Both Adcom and HK actually safe with 2 ohms. My el-cheapo technics rec. When I was in high school could power 4 ohm speakers safely, but stated not to go below 4ohm speakers. Shouldn't any quality amp be able to handle a 4 ohm load . I would sure hope a 1K amp would.
 

swampcat
Unregistered guest
Harmon Kardons had huge power supplies not only in their power and int amps but also their rec. They had 30- 50 amperes per channel depending on what model rec. you purchased . I guess HK has gone down the drain!
 

Unregistered guest
I just installed my dad's Bose 501 Series II speakers from his basement in my living room. Of course, none of my Dolby Digital receivers handles 4ohm loads. So, (a) I add an AMP, or (b) scrap the Bose...
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 725
Registered: Dec-03
that's upto you beej.

you will get a lot of people hear telling you though.

to forgo the old bose their is much better!
not worth getting an amp for.
 

FrankE
Unregistered guest
I NEED HELP! 4 ohm vs. 8 ohm issue here - folks, I have a Harley cruiser with a blown speaker. I removed the speakers (crap) and replaced them with a pair of Polk Audio speakers, SWEET! Unfortunately, I am getting a strange intermittent "clicking" noise and either a drop-out or interuption of some sort in the sound - very disturbing! Now, I noticed the old speakers were labeled 8 ohm, the Polks are 4 ohm. Based on the messages above, it sounds like my stock HD receiver is not able to handle the 4 ohm speakers, is this correct? I think the stock pushes about 40 amps,I REALLY don't want to add an amp. Is power the problem, or do I have a bad match for speakers?
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 977
Registered: Dec-03
well if your old speakers are 8 ohms and the new
ones are 4ohms plus your getting intermittent that
you didn't get before.

it sounds to me your amp does not handlke a 4ohm load.
as many don't.

so you either need to replace the speakers with 8ohm.

or change the amp.

you could talk to the manufacturer and see if their is
an internal part that could be changed to accept
the 4ohm load.
 

GeoB
Unregistered guest
Has anyone had any experience with adding a 4 ohm resistor in series with the speaker to protect the 8 ohm amp, and still use the 4 ohm speakers?
 

Gold Member
Username: Kegger

MICHIGAN

Post Number: 1288
Registered: Dec-03
geob it would work but to be used on all frequencies at the
same time would make that 1 heavy duty resistor.

and would have to be of extremely good quality to
not adversely affect the signal.
which would make it very expensive.

not a good idea in my mind.
 

Anonymous
 
I just bougth a NAD T742, I found it at a good price.

Now I am a little confused. In the manuel it is stated that there is minimum impedance of 8 ohm. It's looks like an advice for having the best quality, there is no warning sign near it.
At the datasheet you find IHF dynamic power specifications down to 2 Ohm. Is there a risk of overheating if I connect 6 Ohm speakers ?

I have old Mission speakers with a 6 Ohm specification and still older IMF speakers with a "4-8 Ohm specification (see graph)" and in the graph I think to see something arround 6 Ohm.

I would like to use those speakers until I know what I want for speakers and see a good deal on them.

Thanks for any help.
 

salsero22
Unregistered guest
Hello everybody, Im planning to buy a pair of polk audio sli9 b.s.speakers and I'll like to hear somebody else opinion, what are my options on a/v receivers? since I plan to build a 50/50 surround system for my basement (with budget on mind). Am I need to stick with 4 ohms all around? I'm a rookie and need some advice, Thanks
 

HK & Polk Fan
Unregistered guest
I have the HK AVR 8000, I drive 4 ohm Polk LSI 15's and they are awesome, I would not hesitate to buy a used AVR 8000, it is a better amp than the new AVR 7200, they quit making mine in 2003 so they could make the new line 7.1 and more affordable, dropped lots of stuff, bottom line it is high current and absolutely rocks, and the LSI's are amazeing, they don't get near enough acknowledgment.
 

Farmer
Unregistered guest
Sorry to help beat the 4 vs 8 ohm subject to death, but.......getting off the beaten track, I'd like to keep the OEM stereo in my Allis Chalmers combine (anybody else out there driving one?). The original 4"x6" speakers are 8 ohm and shot. Any ideas where I can get an 8 ohm replacement? I'd rather not go the autoformer route.
 

Farmer
Unregistered guest
I should have mentioned; OEM replacements are not available for this early '70s' machine.
 

Unregistered guest
I bought a Yamaha VX-1400 receiver. Its rated 110 watts per 7 channels. It had a 6 ohm and 8 ohm speaker selection, but my polk LSI's 25's are rated at 4 ohms. Would it be better to select 8 ohms or 6 ohms on my receiver. I aslo placed the Z fan 2 on top of the receiver and it made a huge difference in cooling down the receiver.
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