[RDavidson]

It ALL matters (speaker design, amp design and topology, etc etc), which is why speaker / amp pairing should be given more thought than the common practice of just buying all the watts one can afford. Of course, there is the "safety factor" of having all those watts, but this doesn't guarantee best sound or best sound to you.

Understanding your listening preferences and being open-minded to experimentation / learning is key.

[FullRangeMan]

What about current delivery?

A pair of Wyred 4 Sound sx500 monoblocks have 35a of current but put out 250 watts into 8ohms. An Odyssey Khartago monoblock has 120a of current and puts out 110 watts. Should there be a big difference in performance in regards to watt output or does the extra current in the Khartago create a different dynamic?

Maybe another way to pose this, is watt output the final say on how an amp handles a speaker or does other factors like current and bandwidth help determine it as well?

Hi current amps are useful to drive big woofers, which have a heavy cone, usually MMS +100gr for 15'' cone.

Hi voltage amps are useful to drive planars.

[Tyson]

A while back I had a chat with a forum member about amps with high watt output vs amps with lesser watts but designed different and still providing excellent bass and slam. Neither one of us understood why an amp that supposedly puts out far less watts could perform just as good if not better than an amp with twice the wattage.

I guess I've always been under the impression that more watts the better when it comes to an amp and would often hear the old " there's no replacement for displacement " when asked why.

I've had some class d amps over the years with often at least 500 watts per channel and recently have had some Crown XLS 1500 amps bridged putting out 1500 watts per channel. Yet when I inserted a Job 225 stereo amp putting out about 180 watts per channel into 4 ohms I got as good dynamics and very comparable if not better bass and slam. Is it just the difference between class d and class a/b?

Does the overall design philosophy of an amp trump high wattage capability? I think this is what I'm trying to ask...

Any comments or thoughts is appreciated and any informational links is a plus!

Thanks!

SS amps turn nasty, very nasty, when they hit clipping.  This is why you want a lot of headroom with them.  Tube amps do not turn nasty at all and their "clipping" is more like "just stops getting louder" than anything else.  So tubes require far fewer watts to sound good.

SS amps also tend to be designed by people heavily concerned with specs, so you often end up with designs that use a lot of feedback to hit those design goals, and the result is a bleached out or sterile sound that has a "samey" sound on pretty much everything and doesn't sound engaging no matter how much you turn it up or how much headroom the amp has. 

As for perceived dynamics, in my experience the mid-level and micro dynamics matter more than the macro dynamics for most music.  Who cares if peaks hit 120db if the slam between 80db and 100db is thick and slow.  Tracking mid and low level dynamics has a lot more impact on how forceful and dynamic an amps sound is perceived to be.  The ironic thing is that you don't need a ton of watts to hit 100db, especially for transients.  And this is why moderately powered amps can sound better than higher powered amps.

[Tomy2Tone]

Understanding your listening preferences and being open-minded to experimentation / learning is key.

This seems to be my experience thus far. More watts doesn't necessarily mean better performance to my ears. Amp "A" may have 5x the watts but amp "B" may have the preferable tone and presentation with dynamics to go with.

I guess I was just surprised how well the Job 225 performed on my speakers in comparison to other amps. I wasn't expecting the dual 8" woofers to get the workout they got from the Job.

[RDavidson]

......and this is kind of why Nelson Pass has such a HUGE following. He makes big power and lowish power amps with the same philosophy. To top it off he DOES NOT let specs drive his designs. He relies on listening tests, simply because listening is what matters. Specs don't make the amp, but his amps always measure well too. So, from that perspective, if you like the Pass Labs / First Watt sound, it generally becomes a matter of understanding your listening preferences which inform your power requirements (with respect to speaker design).

And I will admit....I've become quite an admirer of his work.

[undertow]

I know there will be lots of hemming and hawing about this, however here it goes.

Any amp asked to perform optimally under about 50 hz is doubling even tripling its capability with watts or current delivery.

Most amps today in solid state or tube will perform, but not necessarily at levels to satisfy with very difficult speaker loads, low efficiency, or demanding 25 hz bass out of a tower running on passive crossovers.

I was always an advocate of simpler the better and for years only wanted "Full range" speakers capable of it all in order to run one good quality amp to meet all the frequency needs. This is difficult, and after years finally went to the darkside.

Now I found using passive speakers with above 92 db not demanding subsonic low frequency response you can do very well adding active powered subs, and 9 times out of ten the performance will be better, and even cheaper going this route. Sure tuning such a system is a little trickier, but we are audio nuts so all the time in the world for that!

This also opens a huge variety of very good tube or solid state amps providing anything from 10 watts to 100 watts easily surpassing the sound output or quality of being forced into 400 watt mono blocks to run un-efficient monster towers.

An example which is sorta extreme is when I had Avantgarde Trios... 20 watts with 1000 watt subwoofers could not be matched or even close vs. Sonus Faber box speakers with 600 watt Mcintosh monos in pure power, and control.

The higher efficiency speakers tuned to 50 or 60 hz and up on passive filters adding an active subwoofer will win out every time regardless of wattage, and again likely be using higher quality amplification for even less money in many cases.

By the way in the example above horns running only 90hz and above takes HUGE stress off any amp to sound far more dynamic, silky, tonally musical, and all the other derivative pay offs. Simple electro/mechanical physics.

Eliminate the low frequency duties, and any good amp is even better again being less to do with 3db extra headroom here or there due to wattage differences. 

So the real question here should be "Mo wattage Mo better when you want to run 100% full range main speakers".

[Guy 13]

I know there will be lots of hemming and hawing about this, however here it goes.

Any amp asked to perform optimally under about 50 hz is doubling even tripling its capability with watts or current delivery.

Most amps today in solid state or tube will perform, but not necessarily at levels to satisfy with very difficult speaker loads, low efficiency, or demanding 25 hz bass out of a tower running on passive crossovers.

I was always an advocate of simpler the better and for years only wanted "Full range" speakers capable of it all in order to run one good quality amp to meet all the frequency needs. This is difficult, and after years finally went to the darkside.

Now I found using passive speakers with above 92 db not demanding subsonic low frequency response you can do very well adding active powered subs, and 9 times out of ten the performance will be better, and even cheaper going this route. Sure tuning such a system is a little trickier, but we are audio nuts so all the time in the world for that!

This also opens a huge variety of very good tube or solid state amps providing anything from 10 watts to 100 watts easily surpassing the sound output or quality of being forced into 400 watt mono blocks to run un-efficient monster towers.

An example which is sorta extreme is when I had Avantgarde Trios... 20 watts with 1000 watt subwoofers could not be matched or even close vs. Sonus Faber box speakers with 600 watt Mcintosh monos in pure power, and control.

The higher efficiency speakers tuned to 50 or 60 hz and up on passive filters adding an active subwoofer will win out every time regardless of wattage, and again likely be using higher quality amplification for even less money in many cases.

So the real question here should be "Mo wattage Mo better when you want to run 100% full range main speakers" .

By the way in the example above horns running only 90hz and above takes HUGE stress off any amp to sound far more dynamic, silky, tonally musical, and all the other derivative pay offs. Simple electro/mechanical physics.

Eliminate the low frequency duties, and any good amp is even better again being less to do with 3db extra here or there due to wattage differences.

Hi undertow,
I agree 100% with you and that the kind of system I have now.
Omega 7F extended range driver in open baffle dipole configuration for above 100Hz
driven by a Decware SE84C+
and below the 100Hz it's two Eminence 12" Acoustinator
Open baffle dipole with GR Research solid state 250 watts plate amplifier on each sides.
Best sounding system up to now, after 50 years of searching.

Guy 13


 

[undertow]

Guy 13,
Very cool... Yes at your 100 hz you really open a HUGE range of more than satisfactory amplification to choose from for perfectly tailored sound.

One more thing I will add - Even those HUGE P.A. Systems or line arrays that run ENTIRE concert Venues are simply running around 80 hz and up in most cases. Visceral power comes from all the active equalization and 1000 watt crowns because they don't have low frequency duties. Otherwise they would never achieve the live levels they do. Then of course they have re-enforcement via dedicated Sub woofer arrays.

In your house you will never require anything this crazy (okay some people will  ), but the theory still applies. Essentially you can have a 50 watt killer Class A amp with a sub or 2 and your in business with the right speakers of course not forcing you to power below 50 hz or so. And its not to say a 600 watt Class D amp with some full range speakers won't sound or work great, but that is beside the point of how critical wattage is or not to achieve this goal.

[Tyson]

This seems to be my experience thus far. More watts doesn't necessarily mean better performance to my ears. Amp "A" may have 5x the watts but amp "B" may have the preferable tone and presentation with dynamics to go with.

I guess I was just surprised how well the Job 225 performed on my speakers in comparison to other amps. I wasn't expecting the dual 8" woofers to get the workout they got from the Job.

And is the reason I've built two F5's, a Burning Amp 3, and have a Aleph J in the works....

[Tomy2Tone]

Thanks for all the replies everybody!

[undertow]

"I guess I was just surprised how well the Job 225 performed on my speakers in comparison to other amps. I wasn't expecting the dual 8" woofers to get the workout they got from the Job."

Another thing to keep in mind with the Job 225 specifically :

It is a VERY high gain amp. The input voltage gain is something like 35 db I don't really know of any others on the market quite that high. Even most of the higher ones out there are between 28 and 32db. I had one and you almost had to run passive preamps, OR very standard efficiency speakers from 86 to 92db in order to have control over the volume.

So in this case I can see that the Job 225 even vs. a 500 watt crown or class D would excel simply due to the boosted signal will add that extra bass power especially at lower volume levels because of the high sensitivity of the amp. Essentially the Job has 35 db of gain, that is double the volume level being 10 db higher than most standard amps which generally are around 24 to 26 db gain.

Trust me I owned it, so with a 88 db speaker the Job will be more dynamic regardless of wattage because of the added gain in many systems.

[RDavidson]

Undertow, I see what you're saying regarding "perception" of more power (particularly at comfortable listening levels), but the input gain/sensitivity doesn't somehow make an amp actually have more power or have more dynamic capability at the output stage ; The Job is still 125 wpc. All it means is that it takes less voltage from the source or preamp to reach full output.....which, as you noticed, can make preamp matching tricky. But that's a topic for another discussion.

If it is all up to the input gain of the amp, then by line of reasoning, the OP could just buy a preamp with higher output voltage and achieve the same perceived power and dynamics with amps of lower (ie average) input gain/sensitivity.

In a roundabout way, maybe we're saying the same thing?

[undertow]

Yes you are saying the exact same thing. Point was 35 db is much higher than most amps and will be easily more dynamic at normal listening levels vs. possibly a 25db input amp was the point. No doubt you can crank that 25db amp up more and get that dynamic level of power to kick in, the point being the "Perception" on that it feels just as powerful even though its 125wpc due to a big difference in useable gain.

Yes a 10 db higher preamp could achieve the same. Which there are a few, for example most active preamps I see average around 14 db of gain, and there are some like VAC tube pres as high as 25 db which would cause the same "Perception". I think it sorta comes down to that crazy Munson curve thing the old timers talk about as well where a volume level changes more over some linear period, your getting that Munson curve to kick in differently having all that gain on tap vs. simply wattage making up for it.

One issue I will point out though upping your gain a lot on the preamp side vs. your AMP side is that your outputs controlling power subwoofers will also cause those to probably blow way out of range and you will be turning your subs way down to rebalance. On the Job 225 your only going to make a less efficient 88 db speaker sound more like an efficient 94 db speaker alone without effecting all your other line levels on top of it. Another argument is with the higher gain on the preamp might amplify even more noise from the sources, less so with high gain at the amp end in general.

[RDavidson]

Good points, undertow.

Something else I'd like to point out, based purely on my experience of some higher wattage amps (class A/B generally) is that they need to work (ie be stressed a little) to flesh out and sound their best. I don't know exactly why. Part is probably Munson curve. Part of it could be some kind of pleasing distortion. Part of this could be due to gain. Hard to say exactly, as there are many variables. I think it stands to reason a bit that makers of higher power amps make them with the expectation that the consumer "needs" the power and will stress the amp enough to where it is operating in its sweet spot. So, most of the time, high power amps will sound best with lower efficiency speakers. That's not to say there aren't exceptions. As a side note, I find class D amps to sound quite consistent regardless of speaker load or listening level. They're rather unique in that way.

So in the OP's example, perhaps the Job is working in its sweet spot with his speakers' load and listening levels. This is what you call speaker / amp / listening level / room synergy, folks. As someone else said "there's no replacement for displacement," I have to say there's MUCH more to it. Not everyone wants or needs a top fuel dragster engine in their Shelby Cobra. It's about power to weight ratio and doing more than going in a straight line down a flat track. Like the way roads twist and turn and rise and dip, music ebbs and flows and speeds up and slows down. Finding the balance that works best for you for the roads you like to travel is a tricky thing if you wish to pursue it. For some, a top fuel dragster is simple and enjoyable. Luckily, there's no singular way to go about all this stuff, so just have fun. It's about your enjoyment, not ours.

[undertow]

I was going to argue that earlier  "there's no replacement for displacement" ... Sure there is and the replacements are :

-Impedance
-load
-Efficiency
-Gain
-room size
-Synergy
-Quality
-Solid state vs. Tube
-Analog vs. Digital
- and maybe 50 other things

Does that mean "displacement" is right or wrong... No, just different.

Again your going to force a square peg thru a round hole no question because you can do it a million different ways. Some are easier, some are cheaper, and some are simpler. And none are all together, or one or the other! Combinations.

It comes down to either running more power cables to actively power with more amps to your lower octaves, and having the outlets to do it along with the room setup etc... then any 20 watt S.E.T. will hit the same levels as any 1000 watt Pass amp connected to the right speaker. Is one a better way than the other? It all depends.

Every variable comes into play when trying to use the basic building blocks of real audio performance compared to outright value.

It is possible displacement is not substituted easily when working with very serious loads, and low efficiency like some of the Wilson, Snell, and MBL audiophile speakers.

I have heard 83 db - 2 ohm or lower MBL speakers and in this case you may be hard pressed to get everything out of them without 300 to 400 watts of brute force like their monoblocks, and an extra 200 bucks a month on the electric bill! But why? Does it sound great... Yes it can, and I have first hand experience. Would I do it...? No.

[JLM]

Pick amps to match the speakers (speakers have a much harder job to do and are a much bigger factor on the sound the system produces).  In general, follow the manufacturer's guidelines and aim towards the up of the range.

Tube amps tend to sound better at lower volume, solid state at higher.  As mentioned above tube amps gently clip (round off the peak signals) at maximum output, which is much easier on the speakers, while nearly all solid state amps hard clip (suddenly flatten the peaks) that can destroy speakers so more watts is advised with solid state.  Traditional tube amps have/had poor damping factors leading to bass bloat while solid state have such good damping it can lead to anemic bass.  Another consideration is that any amp must have sufficient wattage to have a commanding grip on the speaker (low wattage amps can greatly suppress dynamics and affect detail/imaging).

Generally speaker efficiencies range from 82 - 104 dB/w/m.  In my experience higher efficiency speakers usually have more colorations but are more dynamic with the ideal speaker efficiency compromise around 92 dB/w/m.  Efficiency is dependent on the drivers used, but bass extension (as mentioned above), and cabinet size/design are other factors.  Room size is another consideration, but less of a factor than many would presume.  With two speakers and an average room, the rated efficiency is roughly the efficiency you can expect in use.  The rub is that wattage is a logarithmic relationship to sound pressure (dB), so it takes 10 times the wattage to go up 10 dB (which sounds twice as loud).  Noting that any self respecting audiophile would want to fully recreate the original, classical/jazz peaks are accepted as 105 dB and rock runs at 110 dB, you can calculate the wattage needed for a given speaker that ranges from 6 dB (7 watts per channel) to 28 dB (300 watts per channel).  Adding EQ/DSP/etc. can greatly increase the power needed.  So tube amps tend to be paired with higher efficiency speakers and solid state with lower.

As mentioned above, bass requires more power than treble frequencies, thus interest in tube amps for tweeters and solid state for woofers.  But that means you're listening to two different amps via two different drivers thereby losing coherence (no designer of active speaker use different amplifier designs for woofer/tweeter).  To a limited degree, the same applies to using the low voltage connections on powered subwoofers.

Example of an amp/speaker matching problem:  the popularity of solid state amps as all but killed Klipsch audiophile speakers because they're very efficient so they operate at low wattage where tubes sound best and solid state sound worst, were designed to use the poor damping of traditional tube amps to reinforce bass (not uncommon with horn loaded speakers), and made volume controls on big wattage amps function in a very limited range (hard to use).

[Tyson]

Active bass sections are a very good solution to allow the use of a SS amp on low frequencies and a tube amp on the mids/highs.  It also lets you have more efficiency and less compromise on the top end.  System matching, as you mention is critical and indeed starts with the speakers. 

I should also point out that high gain amps are generally a bad idea unless you have a low gain preamp - otherwise you have to keep the volume turned way down on the preamp and you lose resolution and performance when that happens. 

[Tomy2Tone]

What is considered high gain for a preamp?

The Rogue Perseus I have now has a gain of 12db and seemed fine with the Job. I have a Herron vtsp 3a coming this week that has an option of either 6db or 12db. Looking forward to it!

I have a pair of Kismet monoblocks coming from Klaus that I've been told has a gain of 30db so I'm looking for a good match between them and the Herron. Like someone mentioned my speakers are 4 ohm nominal and 87db sensitive.

[Tyson]

A really low gain preamp would be zero gain   I joke but it's true, some amps are passive or otherwise have no gain.  I think 12db and under and you'll be fine.

Here's the practical rule I have for myself - most preamps have a point that's called "unity gain", where the signal is not attenuated, and is also not boosted.  Usually it's around 12 o'clock on the dial.  If most of my listening is around 12 o'clock, that's usually a good match.

[Tomy2Tone]

I've read some of the older CJ preamps had a gain in the 20's so I figured 12db would be considered low. I believe Odyssey's Candela has a gain of 14db and obviously goes with Odyssey amps so I'm hoping the Herron will be a good match as well.

I tried a passive pre before but it did not have the resolution that I get with the Rogue, apparently the dac has to be up to the task for the passive to do its thing.