"Pure Class A"

[Ajani]

Since there are no advantages of owning hard to drive speakers.....

You mean other than that the person might really love the sound of a particular set of hard to drive speakers?

If the speakers someone likes have high sensitivity, then certainly a low powered Class A amp should be a top consideration.... but if someone happens to really like the sound of an inefficient pair of speakers, then a big class AB Brute is probably going to be a better choice...

[Jim Eck]

You mean other than that the person might really love the sound of a particular set of hard to drive speakers?

If the speakers someone likes have high sensitivity, then certainly a low powered Class A amp should be a top consideration.... but if someone happens to really like the sound of an inefficient pair of speakers, then a big class AB Brute is probably going to be a better choice...

My Legacy Classics (these can be ran 4 ohm or using the crossover, split to 8 ohm via 2 amplifiers) are not inefficient but they do require power to do their best, I have ran them with less power but have found the more power they receive the better they sound. Currently I am running 2 250 WPC (8ohm) amplifiers to them, one driving the low end and the other driving the high end, I have yet to clip them, but give me time.

Jim

[Geoffcin]

Since there are no advantages of owning hard to drive speakers.....

RGA, please refrain from off topic remarks like this.

[bobsticks]

Any one heard of these? http://www.jamnaudio.com/claytonaudio.html

Frenchmon, care to guess why they are called "Clayton" Audio? They are pretty expensive as well. Not like a Pass monoblock but several thousand. I heard a pair of the CA monoblocks drive the Dynaudio Sapphires and it was amazing.

I heard that exact setup the last time I was down about your way...and was, indeed, amazing...

[E-Stat]

Well that leaves my speakers out as I've pushed every amp I've ever owned into clipping.

Mine, too.

rw

[mlsstl]

...care to guess why they are called "Clayton" Audio?

I just assumed it is because they are located in Clayton, MO, an upscale suburb of St. Louis.

[audio amateur]

Well that leaves my speakers out as I've pushed every amp I've ever owned into clipping. (and I've had some brutes too) Really though, most modern amps have more than 8 watts, unless we're talking about S.E.T. amps and that's a discussion for another thread. (even though SET's are all Class "A" in design)

Didn't you say you drove once your 3.6s with a Trends amp?

I believe anyone can push an amp into clipping on purpose, however doing so on normal program material at moderate listening levels (<80dB) is a different story.

[Feanor]

Mine, too.

rw

You guys must listen awfully loud. I've never driven any amps to clipping with my Maggies, not even my 40 wpc NAD or my 30 wpc, circa 1972, Harmon Kardon receivers.

[Geoffcin]

Didn't you say you drove once your 3.6s with a Trends amp?

I believe anyone can push an amp into clipping on purpose, however doing so on normal program material at moderate listening levels (<80dB) is a different story.

Actually I drove mt 3.6's with a battery powered "T" amp on a lark. Don't get me wrong, I'm not saying that you NEED a super powerful amp in every case, but in MY case if you want to recreate the dynamics of a concert then yes, your going to need some watts.

[mlsstl]

...if you want to recreate the dynamics of a concert...

That may be true of live classical music, but it is pretty rare to have an extraordinary dynamic range on a recording.

Digital recordings have a very hard maximum limit. Analog clipping is a bit softer, but there is still a practical limit on LPs and tape. Once you're at 0 to 3 dB on the VU meter, there just isn't any practical headroom above that. (The exact point depends on the recording equipment and the calibration of the meters.)

I've transferred well over 2,000 LPs and tapes to digital for my music server, so I am very used to looking at the dynamic range on rock, jazz and classical records. For most records, it is very unusual to have an average recorded volume level that is much under 10 dB from the peaks on the record. Even in classical, you might see 20 or 30 dB down from the peaks, but remember the soft sections are exactly that. They should be played at low volume. If you are playing the playing the soft sections of Dukas' "The Sorcerer's Apprentice" at 90 dB, you are way off the mark in terms of what you'd hear live at the symphony.

Keep in mind that even on orchestral classical music, the microphones are far closer to the orchestra than anyone in the audience would be at a live event. And, very few classical recordings are made these days that don't also include highlight mikes. I noted the other day that the Emerson Quartet used 14 mikes to record their version of Mendelssohn's "Complete String Quartets." That's for four string instruments!

This idea that you can be cranking along, listening at 90 or 95 dB and need the headroom for a 30 or 40 dB peak is a situation that simply does not exist on any recording I've ever seen. And that is without even considering the current crop of recordings that have fallen prey to the loudness wars.

[E-Stat]

You guys must listen awfully loud. I've never driven any amps to clipping with my Maggies, not even my 40 wpc NAD or my 30 wpc, circa 1972, Harmon Kardon receivers.

The big Sound Labs require lots of power, especially when there is serious bass content. 600 tube watts gets me peak levels no higher than about 90 db at my listening distance. I'd really like to have double that for classical content.

The double Advents, however, will really rock out with the 400 watt '81 Threshold Stasis. At Halloween, I took the garage system (and preamp from main) to my neighbor's back yard for his daughter's party. There I could get higher levels of very clean output! As DJ, I wore my tux and Phantom of the Opera cape and mask.

System
View from "stage"

rw

[audio amateur]

System
View from "stage"

rw

I bet you were worried sick and incubated them during the whole evening

[E-Stat]

I bet you were worried sick and incubated them during the whole evening

Initially I was concerned about taking out a tweeter since I normally run them at comparatively low levels in the garage (like -20 db). Because this was attended by 13 to 15 year olds, I wasn't concerned about some drunk cranking the preamp. After four hours of running the amp wide open, however, the Advents survived the event. Ferro-fluid cooling works! At a distance of about twenty feet back, they sounded pretty awesome and totally devoid of the electronic grunge and hardness you get with most sound reinforcement gigs.

rw

[Ajani]

The big Sound Labs require lots of power, especially when there is serious bass content. 600 tube watts gets me peak levels no higher than about 90 db at my listening distance. I'd really like to have double that for classical content.

The double Advents, however, will really rock out with the 400 watt '81 Threshold Stasis. At Halloween, I took the garage system (and preamp from main) to my neighbor's back yard for his daughter's party. There I could get higher levels of very clean output! As DJ, I wore my tux and Phantom of the Opera cape and mask.

System
View from "stage"

rw

Judging from the chalk outlines on the ground, I'm guessing some of the kids tried to steal your equipment and you had to teach them a hard lesson...

[audio amateur]

It's nice that you could help out like that. I'm curious as to what tunes were played

Do you wire the Advents in parallel or in series?

[E-Stat]

Judging from the chalk outlines on the ground, I'm guessing some of the kids tried to steal your equipment and you had to teach them a hard lesson...

LOL! Actually, that "prop" was suggested by the Mom. I modeled for one of the outlines - which caused the daughter, her friend and brother to say "Do me next!"

rw

[E-Stat]

It's nice that you could help out like that. I'm curious as to what tunes were played

They were chosen by the thirteen year old girl and her Mom if that helps! It was a mix of classic Halloween stuff and a bunch of current teen pop stuff. One guy brought over a CD with "PT Cruiser". The neighbor who lives on the other side heard that and in jest wondered what it was. He used the "Shazam" app on his iPhone, found out and downloaded it. It really is a repetitious song with few lyrics beyond the title. He's really funny singing that song! I still have the ripped content, but with no titles. I just "Shazammed" a couple more:

"Skanky Legg" by the GS Boyz.
"Krazy" by Pitbull Feat. Lil' John
"Battlefield" by Jordin Sparks
"I'm a Flirt" by R. Kelly

Never heard any of these, but then I'm an old guy.

Do you wire the Advents in parallel or in series?

Definitely parallel with separate runs to each speaker. They present a nominal 4 ohm load that drops to 2.3 ohms in a couple of places. Which is a piece of cake for an amp designed to drive Dayton-Wright electrostatics.

rw

[RGA]

I think if you add distortion (THD) to the mix, you will get a different picture of what you stated.

As you said 8 watts of power will certainly get loud, but distortion will be high due to not having enough Dynamic Headroom to handle power spikes. This is where more power is welcome to keep [even&odd] distortion low.

In another word more power is not about quantity, but rather quality

Actually that is true but you can get around that with speaker efficiency. And the type of distortion from tube amps is easier on the ears - while the SS sound is always present at every volume.

100db sensitive benign impedance load speaker and a 8 watt amp

1w = 100db (90db is considered loud and with prolonged use at 90db will cause hearing damage) - 1 watt is 1/10th the amplifiers output and is already giving you 10 db over what is consider Loud. 100db is very loud
2w = 103db
4w = 106db
8w = 109db (These are leave the room volume levels - and in fact 100db for most would be leave the room volume levels. Typical listening is in the sub 85db realms - so all dynamic swings are easily covered.

85db speakers with a 100 watt amplifier

85db - 1 w
88db - 2w
91db - 4w
94db 8 w
97db 16w
100db 32w
103db 64w
106db 128watt.
109db 256w (To get the same level (dynamic headroom included would require 256watts to get the same level dynamic headroom included as the system above. - but the question is how many speakers of 85-87bb ilk can truly take sustained 256watts - not a whole lot I can tell you that - most standmount varieties can handle 80-120 watts.

The first system will have more volume and more dynamics that system two.

Of course if one insists on using the 85db speaker then you have to have more power - the problem is for me that as good as some of the hard to drive speakers are - the foibles of the amplifier ruin everything for me. The best "sound quality" I have ever heard from the N801 was with a Wyatech 11 watt tube amp - but unfortunately you could not play it very loud. But put on a MF or Bryston and the sound was better in the off position.

This is the same with panels - I liked the Quads better the second time around with low watt tube amplifiers - and the 2905 has a flat impedance and the tube amp was never really put in distress. Brilliant sound.

At the very least - if you are running a conventional boxed speaker of low efficiency get a tube preamp SET stage on in there and maybe even a tube hybrid monoblock stage like the Shengya PM 150's. Or a pure class A Single ended solid state design like Pass Labs or the Sugden Masterclass series.

At least "try" them alongside the usual class A/B culprits.

[RGA]

You mean other than that the person might really love the sound of a particular set of hard to drive speakers?

If the speakers someone likes have high sensitivity, then certainly a low powered Class A amp should be a top consideration.... but if someone happens to really like the sound of an inefficient pair of speakers, then a big class AB Brute is probably going to be a better choice...

My speakers are 89.5db (92.5db in corners) and I run an 4-10 watt amp (4 without distortion). This is not exactly huge sensitivity so there are plenty of substitute speakers out there that can play real loud without dynamic compression on 8-10 watts.

I suppose I really amp in the front end matters most camp because it makes little sense to uses a garbage in to a speaker that can only use garbage in amplifiers. I think most people would want to keep their options open on the front end - with a HE speaker you can use ANY amplifier of any power rating. And in general HE speakers can also play a helluva lot louder than lower efficiency speakers - which is why rock concerts use horns not panels.

If one is truly serious about very loud Guns and Roses you go with something like the big K-Horn or Tannoy studio series double 15 inch woofer jobs that actually still sound good - certainly for this kind of music. You can run a 5 watt amp that will blow you out of the room - there are always high power class A very low feedback tube amps around.

Because honestly - a 300 watt SS amp on a set of 83db Totem's or pretty much any and all multiple stacked 6 inch woofer array playing AC/DC is a joke - no matter what amplifier power you have - the speaker can only take so much.

[RGA]

You guys must listen awfully loud. I've never driven any amps to clipping with my Maggies, not even my 40 wpc NAD or my 30 wpc, circa 1972, Harmon Kardon receivers.

Here's the thing - I was at a listening session a few years ago with Odyssey Stratus amps being run as monoblocks - I am guessing but something like 200 watts per channel running Gershman acoustic X-1 sub 1 and playing pretty darn loud - we measured the level ~75db. we could talk over the music but at elevated levels. This would not have used more than a watt of that system. Putting on a Class T amp of 5 watts and it was fine. It was better on the AN K power wise but the K is easier in the impedance department.

I seriously doubt owners sit at home and play 8 hours every day day in day out of deafening levels where you have to scream at the top of your lungs to the person beside you. If you do you lost your hearing years ago and quality doesn't matter.

Buy the quality SET amp for your 99% of usual listening levels and if you really want to impress your friends for the 5 minutes you can stomach extreme levels - buy a Crown for $100 but don't suffer the other 99% of the time listening to inferior sounding amplifiers just to have the odd ridiculous volume level session.

I mean I keep my Vanguards around for this very reason - If I want the 120db sessions - but those are so few and far between that the speakers are taking up space in a closet. Partly because the standmounts with 4 undistorted watts have already generated enough complaints and I have not even got it to half volume yet!

lastly you can always buy more powerful SE amplifiers for bigger rooms and lower impedance requests. Moreover when you finally have a superior sounding amplifier you don't feel the need to turn it up trying to get volume level to compensate for a lack of resolution.

[Geoffcin]

RGA makes it sound like all you need is a high efficiency speaker and you good to go, but that's simply not the case. MOST high efficiency speakers I've heard are really lacking in lower bass. The only one's that that make passible bass to my ears are huge, and they have to be based on of the basic speaker design principles worked out long ago by the "H" in "KLH" called "Hoffman's Iron Law"

Simply put, Hoffman's Iron Law states that the efficiency of a woofer system is directly proportional to its cabinet volume and the cube of its cutoff frequency.

So, there's no free lunch on efficiency even if you decide to use the room corners as quasi-horn loading.

Oh, and I have heard Totem Mani-2 Sig's playing Guns & Roses. They absolutely rocked out! (with a 400wpc amp no less!)

[E-Stat]

85db speakers with a 100 watt amplifier

85db - 1 w
88db - 2w
91db - 4w
94db 8 w
97db 16w
100db 32w
103db 64w

Remember how this was measured - typically at 1 meter and at an *easy" 1 kHz. As for me, I listen at a distance of about four meters - where the bass is most linear in my eight meter long room. Point source speakers drop 6 db for every doubling of distance, so that would be 12 db less for my position at 1 Khz and lower still in using real world wideband material (not AM radio).

rw

[Geoffcin]

This idea that you can be cranking along, listening at 90 or 95 dB and need the headroom for a 30 or 40 dB peak is a situation that simply does not exist on any recording I've ever seen. And that is without even considering the current crop of recordings that have fallen prey to the loudness wars.

Of course a 40dB peak is nearly unheard of on any program material I've listened to. Even with that being said, sometimes the numbers do add up to needing more power. Here's a clip from a review done a while back on the then new Magnepan MMG, the SMALLEST of the line;

http://www.soundstage.com/entry04.htm

"Let's put this into perspective for you. My Proton D1200 power amp has big, cool power meters on the front that are fairly accurate. I was routinely pumping over 50w/ch into these speakers in routine listening; no way would you want to have less than that and expect to play a set of MMGs at all. When I cranked things up, I could easily drop over 200w into each speaker. At one point, I was using an original Adcom GFA-555 to power the MMGs. For those not familiar with this amp, it's a solid state brute that is rated for 200w/ch of continuous power (even more into this 4 ohm load), and has good headroom to boot. There's two clipping lights on the front of the amp that brighten when you're pushing it too hard. In the five years I've owned this amp, I've seen those lights once, that was during some testing where I purposely beating up on a pair of speakers just to see what the limits where on the amplifier and the speakers were. Hook up these power hungry Magnepans to it, turn the volume up, and those lights start blinking like a Christmas tree. "

[RGA]

RGA makes it sound like all you need is a high efficiency speaker and you good to go, but that's simply not the case. MOST high efficiency speakers I've heard are really lacking in lower bass. The only one's that that make passible bass to my ears are huge, and they have to be based on of the basic speaker design principles worked out long ago by the "H" in "KLH" called "Hoffman's Iron Law"

Simply put, Hoffman's Iron Law states that the efficiency of a woofer system is directly proportional to its cabinet volume and the cube of its cutoff frequency.

So, there's no free lunch on efficiency even if you decide to use the room corners as quasi-horn loading.

Oh, and I have heard Totem Mani-2 Sig's playing Guns & Roses. They absolutely rocked out! (with a 400wpc amp no less!)

You are still limited by the maximum watt figure of the loudspeaker - I keep reading people with 400 watt amplifiers - the Mani-2 has a maximum of 200 watts but it also bottoms out at 110db. So Regardless of the amplifier used the limit of this 85db loudspeaker is

85db 1w
88db 2w
91db 4w
94db 8w
97db 16w
100db 32w
103db 64w
106db 128w
109db 256w

Which is ok - my system achieves the same volume level as the Mani-2 with considerably less watts without going over the max watt intake of the loudspeakers.


And when you get into "true" sub territory an amplified sub for sub 30hz down to sub 10hz the amplifier "sound" is not that important - it's when the amp sound or the sub for that matter is being used for the actual initial sounds of notes. To me subs are best for ambiance and feeling bass - not so much for audible spectrum sound. High efficiency generally has to be big to have bass but they also sound more dynamic than the likes of LE speakers - no matter how powerful the amps.

[RGA]

Remember how this was measured - typically at 1 meter and at an *easy" 1 kHz. As for me, I listen at a distance of about four meters - where the bass is most linear in my eight meter long room. Point source speakers drop 6 db for every doubling of distance, so that would be 12 db less for my position at 1 Khz and lower still in using real world wideband material (not AM radio).

rw

And all that means to me is that you want a higher efficiency speaker even more in a larger room to counteract the db drop at distance. It's still an apples to apples issue.

In a large room with low efficiency speakers - you are correct - SETs will be in real trouble. And bigger powerful ones costs a bomb.

But my contention is that I see no point in having a low efficient speaker and then putting a SS etchy high grain notch distortion ear fatiguing amplifier in the front. If the speaker is High resolution (few LE speakers are fortunately for them) then you will hear with even greater magnitude just how poor the amplifiers are on sound quality. Granted you have Pass Labs right? A SE pure class A no feedback design? You must have decided on it for reasons other than looks no?

Still the best actual sound I have heard with even tough to drive panels and conventional lower efficiency speakers is with SE amplifiers. Yes they are limited with volume capabilities but then why buy worse sounding high power amplifiers? Yes they can play loud but the sound is bad!! Why not keep the better front end and get a speaker that is easy to drive?

The bottom line is this - An AN E with a 10 watt amp in a medium room - 25 by 25 or smaller with Guns and Roses can play to leave the room volume levels to 25 -30hz flat in room at the listening chair. There are bigger high efficiency speakers like the Tannoy Westminster that can play louder deeper and are even easier to drive!! That will beat the snot out of any 1000 watt amp and any panel or any speaker in the size and weight class of the Wilson Sophia. And the Tannoy SET will give you all that oomph and ridiculous drive level and hit you in the chest impact - but it will also make Beethoven sound good. Something that no SE amps IMO just don't do even in the $70grand Krell Levinson systems sound merely average to worse than average. The Tannoy/SET will save huge cash - and save you piles of money. Granted the Westminster is butt ugly but....