What drives 4 Ohm speakers well ??

[Dr Beat]

Not being too technically inclined on speakers and impedance, can anyone tell me what kind of power is needed to drive a 4 ohm speakers well ?? i have been told that if the power is inadequate, the result is that the resulting bass control is weak and loose. Hence, it is easier to drive 8 ohm speakers, such as the ATC SCM 40 or the Proac D18, as they require lower power to drive it.So, a friend explained that you need at least a 200W power amp to drive a 4 Ohm speakers like the Dynaudio Contour series.

Anyone knows whether its all true, or half true, or some truth??? Your guidance and sharing of knowledge is most appreciated.

 

[Anonymous]

The lower the sensitivity of a speaker, e.g. 84 dB W m, the more voltage you need to make it go loud, i.e. you need more Watts of power.

The impedance characteristics of a speaker is a different matter. The lower the number drops at any given frequency then the more difficult a load it presents to the amp. It represents a low resistance and subsequently draws more current from the amp. Thus, lower impedance values will require greater current drive from the amp to keep up. If the amp can't keep up then it will start clipping.

So, a speaker with impedance dips of 4 Ohms and below will beg for current to make it work well, i.e. keep the bass controlled and tight. Dynaudio speakers have a reputation for being current hungry like this. It's not the Watts value that's the problem provided the sensitivity is OK.

All in all you can't think of the current and voltage separately because they both change with respect to resistance, R = I/V.

Naim amps always appear to be relatively low Watt values compared to competitors, but they have good current output. They can drive difficult loads but not to high volumes if the sensitivity is low. Be wary of an amp's stated power in Watts because it's not the full story.

The ATC myth of being difficult to drive comes from their low sensitivity values. They need Watts to get up to high volumes but present a fairly easy impedance characteristic to the amp so can work well with most amps!

 

[Dr Beat]

Hi Iggs

If the speakers have an impedance of 4 Ohms, and a sensitivity of 85 dB, what kind of power amp in terms of watts, do i require to drive it (and control the bass well) ?? 200w or even 120w can do it??

I am also told that if i bi amp the speakers, low wattage power amps, can drive the above type of speakers. Is this true? most of my mates mono bloc but none bi amp. Any benefit other than enriching the amp makers?

Thanks in advance for the advice.

 

[Anonymous]

Biamping just splits the power between the bass and treble. This might improve clarity but not punch as it is the bass that uses the power. If you run power amps in mono (Xpowers do have this option), you are increasing the power so may improve the punch.

 

[Anonymous]

Dr Beat:
Hi Iggs

If the speakers have an impedance of 4 Ohms, and a sensitivity of 85 dB, what kind of power amp in terms of watts, do i require to drive it (and control the bass well) ?? 200w or even 120w can do it??

I am also told that if i bi amp the speakers, low wattage power amps, can drive the above type of speakers. Is this true? most of my mates mono bloc but none bi amp. Any benefit other than enriching the amp makers?

Thanks in advance for the advice.

Typically one refers to biamping when it is horizontal, i.e. one amp to do L-R treble, another to do L-R bass. Mono blocking is often referred to for vertical biamping, i.e. one amp for all L and one for all R. Both should provide you more current capability to drive the speakers but not double the Watts for volume; for this you'd need to bridge the amps, i.e. series not parallel connection.

85 db is fairly low sensitivity so you probably want a higher power amp, maybe 100W and over. That's what I use on my 82dB Spendors.

The 4 Ohm nominal impedance will demand decent current output (a good stiff power supply, i.e. big transformer and output capacitors!) so you should aim for a decent amp, things like Naim Nait 5, Nait XS, Roksan Caspian, Cyrus XPower (and up), Primare I30, Musical Fidelity A5.5, etc. Of course, biamping will give you double the amount of current to play with and will also go louder because it won't clip as easily. It's not bridging though so you won't get double the volume.

It's very hard to decide what power you need because it depends on how close you sit, how big the room is and the nature of the acoustics and reflections. The only way to really tell is to audition!

If an amp struggles and starts clipping then the sound will become coloured and deviates from the recorded sound. Sometimes a bit of colour can make a system more enjoyable so see what you like!

EDIT Please, anyone correct me if this is incorrect!

 

[Dr Beat]

Thanks Guys for the advice. From my signature, you can see that my Dyn Contour S1.4 speakers are being powered by 2x X Power (running in Mono). I sit about 6 ft away from the set up and the room size is about 15ft by 15ft. From Igg's last advice when i was setting the room up, i have carpeted the room and i have a sofa in the middle of the room. Nothing hangs on the wall.

It's just that the bass appears to be a bit loose/boomy on certain bass driven songs. I have bung the ports with acoustic wool (i know that changes the characteristics of the speakers) and supplement the bass with my Quad L-ite sub-woofer. I find the set up good, as i get the mids and highs from the Dyns , but the bass comes with more control from the sub.

It's just that a friend commented that i should not do this. I should unplug the bungs, unhook the sub and do something to control the bass so that it becomes tighter, like getting a new power amp, something around 200W.

Anyone with sound advice? All tips and advice are much appreciated.

 

[Anonymous]

A couple of MonoX should be OK. I have a pair of little Spendor SA1s and have them in quite a large room having moved recently. Even though the room is larger than my old, I find that the bass booms more at certain frequencies with respect to the positioning and listening spot. The fix, not that I can permanently implement it, is to move either placements.

Given that bass response in rooms is strong a room nodes (some sort of bass terminology I have vaguely understood from my sub's manual), perhaps repositioning yourself or the speakers could eliminate the issue. Try just moving them around a bit to see whether it disappears. I would def try to avoid bunging though, and switch the sub off for this experimentation. Be very wary of corners and recesses, and see what happens in positions even if they're not permanently viable.

If you can nail it down a bit more then you could consider trying bass traps in the room, maybe the corners. I've never tried it but maybe you could stand sofa cushions up in various areas/corners to see if it fixes it?! I'm clutching at straws now as you may have gathered

 

[Dr Beat]

Hi

OK, spent the night repositioning the speakers. I removed the acoustic wool and i also detached the sub-woofer. Moving the speakers from 1 feet away from the wall to 2 feet did reduce this "boomy" bass sound. But what i did find out from the experimentation is that when i re-attached the sub-woofer, the overall sound was also much better. It's like the subW took over the low signals from the main speakers. Am i making sense? Well, that's what i think i am hearing.Can this happen?? well, so far so good.

I have arranged to borrow a friend's sub woofer, the Velodyne SPL 1000 Ultra to replace my Quad Lite subwoofer. I will post my findings later. BTW, i playing volume is usually 35 on the Cyrus volume dial.

Any other advice to improve the sound??

Many thanks, and will post later.

 

[Anonymous]

Sounds good. Try toeing in a bit too.

You can get some odd things going on with subs, including bass cancellation where it will reduce some of what you get from the mains.

 

[Frank Harvey]

Dr Beat: Not being too technically inclined on speakers and impedance, can anyone tell me what kind of power is needed to drive a 4 ohm speakers well ?? i have been told that if the power is inadequate, the result is that the resulting bass control is weak and loose. Hence, it is easier to drive 8 ohm speakers, such as the ATC SCM 40 or the Proac D18, as they require lower power to drive it.So, a friend explained that you need at least a 200W power amp to drive a 4 Ohm speakers like the Dynaudio Contour series. You are correct. If an amplifier is not up to the job of driving the speaker properly, you will end up with a loose bass, lacking punch and control. This can be easily demonstrated when trying a better amplifier.

Driving a 4ohm loudspeaker is more about current capability than wpc. You will find many amplifiers on the market less than 100wpc which are capable of quite high current levels, which make them sound louder than their wpc rating on paper. You will also find many higher end 8ohm loudspeakers act in a similar way, needing much more power/current to get the speaker to sing.

I personally find the Dynaudios a little bass heavy, and also loose in the bass. This can be helped with better amplification, but if you're limited regarding positioning away from a wall, and don't want to use the bungs, you may find that this looseness may never be fully tamed.

OK, spent the night repositioning the speakers. I removed the acoustic wool and i also detached the sub-woofer. Moving the speakers from 1 feet away from the wall to 2 feet did reduce this "boomy" bass sound. But what i did find out from the experimentation is that when i re-attached the sub-woofer, the overall sound was also much better. It's like the subW took over the low signals from the main speakers. Am i making sense? Well, that's what i think i am hearing.Can this happen?? well, so far so good.

I have arranged to borrow a friend's sub woofer, the Velodyne SPL 1000 Ultra to replace my Quad Lite subwoofer. I will post my findings later. BTW, i playing volume is usually 35 on the Cyrus volume dial.

Any other advice to improve the sound?? Adding the subwoofer isn't changing the bass response or control of your main speakers, it's adding depth. The best way of tailoring bass with a sub is to take the speaker cables from the amp, through the sub, then select the crossover point you want, allowing you to limit the lower frequencies the speaker has to deal with. The problem with this is that it degrades quality due to the filtering. I can only assume you're more happy with the sound because of it's depth, and possibly having a 'fatter' bass. You may prefer a floorstander, which will give you a similar change.

Your friend saying that you shouldn't use a sub is sort of correct - down to certain frequencies, bass can be directional, which would come across as mono with a single sub. Also, subs are frowned upon by audiophiles. If you have to use a sub, a sealed sub will generally give you a more even in room response, and generally a tighter sound, both preferable for music.

To sum up, I think using a sub subtlely can work quite effectively, but you'll find that it's not going to change the bass problems you're getting from your speakers.

 

[Craig M.]

i demoed them speakers with my moon amp, more then enough power to control the bass.

i'm a bit suprised that you have them in a fairly small room, they liked space to breath in my room.

i would continue to exhaust positioning possibilities before buying a new amp.

 

[Anonymous]

Yeah, two XPowers ought to be a very respectable whack for those...

 

[proffski]

Krell? MF 1KW?

 

[Dr Beat]

Hi Guys

OK, my friend lent me his Velodyne SPL 1000 Ultra. I expected a better reult as it is about twice the cost of the Quad Lite sub that i have. Surprisingly, it was not the case, at least to my ears. I felt the bass was looser compared to the Quad, maybe the crossover setting was incorrect, but i fiddled with the buttons, and still not so good results. So, i am going to reattach the Quad sub.

BTW, i also tried the two subs to my Denon 2310 and Pioneer 320. The Quad was better, IMHO. But this is another topic in another forum.

Back to my issue. Thanks Craig, and yes, the Mrs "gave" me the small spare room. That's all the space allocated for hifi. If you were me, what would you pair with the Cyrus for such dimensions? BTW, Iggs, you may not recall, but i had the Spendor SA1 as my first pair of speakers to match the Cyrus set up. But i sold them to my brother, and got the Dyns. They sounded great at the shop, but they were paired with the Plinius M8/P10 set up. The dealer was not a Cyrus agent.

My Mrs' thought is to trade in the Dyns, take a bit of a hit and get a pair that suits the Cyrus and the room dimensions of course. We did entertain this thought over last weekend and went to demo the Spendor A6, ProAc D18, and ATC SCM 40. These floorstanders hopefully will eliminate the need for a sub, and give me the tight bass control i prefer.

As the Dyns require more breathing space as Craig put it, maybe the obvious option is to trade in the Dyns (and get new speakers ) rather than replacing the amp. It is also a cheaper option.

So, anyone with a helpful thought? Appreciate all advice.

Many thanks

 

[Anonymous]

Sounds like a home demo is needed. What about trying the SA1s in that room again?

EDIT Scrub the SA1 idea, you obviously want a different sound. Home dem is really the only way you're going to be sure about the balance.

 

[Frank Harvey]

Dr Beat: My Mrs' thought is to trade in the Dyns, take a bit of a hit and get a pair that suits the Cyrus and the room dimensions of course. We did entertain this thought over last weekend and went to demo the Spendor A6, ProAc D18, and ATC SCM 40. These floorstanders hopefully will eliminate the need for a sub, and give me the tight bass control i prefer. As the Dyns require more breathing space as Craig put it, maybe the obvious option is to trade in the Dyns (and get new speakers ) rather than replacing the amp. It is also a cheaper option.

So, anyone with a helpful thought? Appreciate all advice. Many thanksI think what you've already said is your first port of call - have a listen to those 3 pairs of speakers and take it from there. Without looking at much more expensive speakers, it's these 3 that are the easiest to incorporate into a smaller room. You amplification will be fine for any of them.

 

[Craig M.]

i went from dynaudio focus 110 to atc 19's and would not go back. the sound is very different to dynaudio and took some getting used to.

i used to have the dyn's pointing straight at me to try and keep the bass under control, in the same position the atc's need no toe in to help with the bass (which is even and detailed) and so you only have to toe in in order to adjust the soundstage.

i think you will find the atc's to be very natural sounding compared to the contours, which i thought were terrific speakers, but perhaps a bit "in yer face" sometimes.

 

[Frank Harvey]

What you're hearing Craig is the difference between a ported and a sealed cabinet speaker. Sealed cabinets give a more even in room response, and are affected less by room boundaries. The only time a ported speaker can sound like a sealed cabinet is when enough money is thrown at it, which is a lot. Having said that, the Dynaudio's are probably at the extreme end of how ported speakers sound, if you get what I mean.