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Why More Power?

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Posted on July 7, 2015 at 12:40:13
pictureguy
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In looking thru the Magnepan CURRENT lineup, they are ALL, at least from the 20.7 to the .7 rated the SAME sensitivity.
So, why keep recommending more power as you go up the line?
Let's say I were to want to swap my 1.6 for some 3.6? My listening habits / levels won't change. So why would I want to swap my PAIR of Parasound A23 for MORE power?
This is not the same issue as power handling, which should go up as you go upline.
Too much is never enough

 

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RE: Why More Power?, posted on July 7, 2015 at 14:30:58
BigguyinATL
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I don't believe there is a need for more power as you go up in Maggie panel size. The peak power limits are based on excursion and perhaps bonding strength of the adhesive or separation strength of the "wires"
Long ternm performance limits (RMS values) will have a temperature and signal crest factor parameter and well.

Independent of the panel size - my limited experience is that the larger panels are not noticeably more efficient.


"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius

 

RE: Why More Power?, posted on July 7, 2015 at 14:47:28
Could the need for more power be related to 'dynamic headroom'?

http://www.axiomaudio.com/dynamicheadroom

 

RE: Why More Power?, posted on July 7, 2015 at 15:27:11
DrChaos
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| Independent of the panel size - my limited experience is that the larger panels are not noticeably more efficient.

Excepting the desktop Mini Maggie, the larger panels have substantially more surface area for bass, but not for midrange or tweeter.

 

RE: "my limited experience is that the larger panels are not noticeably more efficient." ..., posted on July 7, 2015 at 15:45:59
andyr
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Interesting that you think the larger Maggies should be more efficient (which implies they don't need any more power to drive them).

My view is that the 3-way models need more power for several reasons:

1. They have 3 drivers instead of 2.
2. Their bigger bass drivers mean they go down deeper (than the smaller Maggies).
3. Delivering down to 30 Hz sucks up more amplifier power than only delivering down to 40+ Hz.

Andy

 

RE: "Could the need for more power be related to 'dynamic headroom'?" ..., posted on July 7, 2015 at 15:49:39
andyr
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More power indeed gives you more dynamic headroom but the OP's question is surely whether bigger drivers implies more power is needed.

Andy

 

RE: "my limited experience is that the larger panels are not noticeably more efficient." ..., posted on July 7, 2015 at 16:26:11
pictureguy
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Magnepan rates the sensitity at ONE frequency. However, the amount of power needed from 40hz to 25hz (let's be optimistic here) is probably only 5% or so increase. You'd have to REALLY go some to convince me of 10% or greater.

That the panel size is LARGER means, perhaps, more air resistance? Also, the 20 series is double sided, which MAY mean greater sensitivity? apparently not, by Magnepan spec.
Too much is never enough

 

RE: "my limited experience is that the larger panels are not noticeably more efficient." ..., posted on July 7, 2015 at 16:36:03
DrChaos
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| Interesting that you think the larger Maggies should be more efficient (which implies they don't need any more power to drive them).

That's usually the case with conventional box speakers.

As I understand it though the reason for that is matching the woofer response with the mid & tweeters. The mid & tweets are already more than enough sensitive out of the driver but smaller cabinet gives less efficient bass especially if you want extension.

So smaller boxes have to pad down the mid & tweet to match the lower-sensitivity woofer.

Seems that with maggies that isn't the case as much---the mid and tweet are the same, and larger size gives more bass extension and max SPL.

 

RE: "Could the need for more power be related to 'dynamic headroom'?" ..., posted on July 7, 2015 at 20:30:57
pictureguy
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Sure, more power AND larger drivers may imply more headroom or simply that the panel has higher upper power limits with the SAME sensitivity. Yes, it may 'play louder'.
I know voice coil / cone drivers suffer from dynamic compression where increase of power in doesn't result in more output, but does result in distortion and other non-linear behavior.
Maybe panels have a similar mode?
Too much is never enough

 

RE: "Could the need for more power be related to 'dynamic headroom'?" ..., posted on July 7, 2015 at 21:23:26
Work is required for a driver to perform its job. Larger drivers require more work (than do smaller drivers).

 

well you're in good shape with the Parasounds, posted on July 7, 2015 at 21:50:49
Green Lantern
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June 17, 2003
And would do a pair of 3.6's good justice.

Hell I ran a vintage '76 Marantz 1040 int amp (we're talking 20 wpc folks) on my 1.6s back in the old days while my regular amp was out getting repaired. Granted I kept the listening sessions short and sweet and paid careful attention to any heat build up (amp stayed nice and cool btw). Added bonus: it even put out decent bass. I would never recommend such to anyone with Maggies (definitely nothing higher than a 1.6). I guess the audio gods were just kind to me; (or simply on a break ;)









 

RE: well you're in good shape with the Parasounds, posted on July 8, 2015 at 02:08:16
pictureguy
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My original amp with my MG-1s was a Kenwood KA7100 of 60x2 @8 which may have turned into 80 a side @4.
adequate? Sort of, but I could clearly tell the difference adding 4db when I bought my 'cube'.
Too much is never enough

 

RE: "Could the need for more power be related to 'dynamic headroom'?" ..., posted on July 8, 2015 at 10:04:23
pictureguy
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EFFICIENCY, as distinguished from Sensitivity, of speakers, is Under 1% except perhaps in the MOST sensitive speakers.
A speaker with 1% efficiency would be OVER 110db/watt/meter
Too much is never enough

 

'Power' and Maggies, posted on July 8, 2015 at 10:58:51
I'm considering the physical equation for 'Work', W = F X D. (Isn't work required to move a Maggie's diaphragm/membrane?)

If a listener attempts driving a 20.7 with some 'garden type' amplifier, integrated or not, which is more than merely satisfactory to listen to a MMG, what is likely to happen, (even if somehow their impedances could be made the same, 'autoformer')? Perhaps one should substitute a 3.X for the 20.7, and just to screw with your mind, try replacing that MMG with a Tympani IIIB.

Everyone knows the result (as even do I), so what's its electrical or physical basis? Since I don't pretend to know the answer, I'll then ask that question in answer your original question.

 

RE: Why More Power?, posted on July 8, 2015 at 11:02:57
Satie
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To make use of the greater extension and output capacity (power handling) you need an amp that is capable of making use of the extra bass extension and dynamic range.

The speakers may be quoted at the same sensitivity at a particular frequency but there is generally less efficiency at the lower end and even the mids as you go up the line since the same magnets are used while offset increases and surface area increases so you need more power to get full use of the increased capacity (excursion limit X surface)..

If you don't increase the power then you are not going to be able to make use of the increased potential you are paying for.

Prior to the .7 series, the crossovers became steeper as you went up the line and thus required heftier amps to provide the same bass output levels over a wider freq range that is available.

 

RE: "Could the need for more power be related to 'dynamic headroom'?" ..., posted on July 8, 2015 at 13:43:05
DrChaos
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| Work is required for a driver to perform its job. Larger drivers require more work (than do smaller drivers).

But the efficiency of coupling the motion of those drivers into acoustic output, especially at lower frqeuencies, goes up as well.

 

RE: "Could the need for more power be related to 'dynamic headroom'?" ..., posted on July 8, 2015 at 14:26:07
You convinced me, hereafter I'm only going to be listening to my Tympani IVAs powered by an Onkyo TX8511 (which BTW does a fairly decent job with my MMGs).

From crutchfield.com:
"For high-end stereo sound at a remarkably down-to-earth price, check out this impressive receiver from Onkyo! Boasting 100 watts x 2 channels of clean, high-current power, the TX-8511 is a dream come true for music lovers everywhere. Onkyo is famous the world over for their low-impedance amplifier design — and a look inside this model reveals why.
Onkyo pays attention to detail in every aspect of construction. The transformer: oversized and shielded for maximum power capacity and stability, and minimum hum. The filter capacitor: oversized for clean sound during your music's most demanding dynamic peaks. The cast aluminum heat sink: oversized for efficient heat dissipation, and thus longer life from your receiver. Discrete outputs: designed to run cooler, and to keep your music cleaner, under high-volume, low-impedance conditions. Anti-resonant chassis and aluminum front panel: highly rigid to fight distortion-causing resonance."

 

RE: "Could the need for more power be related to 'dynamic headroom'?" ..., posted on July 8, 2015 at 14:33:43
DrChaos
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If you highpassed the input to the amplifier to match the frequency response of the MMG's you'd probably not need more power, all else being equal (which isn't the case---Maggies have also generally increased in efficiency over time).

But obviously people want to use the big drivers, to give substantial output at substantially lower frequencies, so the power needed to achieve desired and feasible results is of course higher than using small drivers to give less. But still less power than trying to make small drivers give the same SPL at the same low frequency!

Otherwise we could use tweeters and headphone drivers full range and we don't.

Anyway, I was thinking more of box-speakers, where higher efficiencies for towers with larger woofers than smaller standmounts are normal.

 

RE: Why More Power?, posted on July 8, 2015 at 14:40:21
You've made this statement previously regarding sensitivity differences in the various models. Your feeling is the nominal (midrange) ratings Magnepan specifies for some/all of the models are incorrect? (Some evidence please to back that up?)

You (and some of the other posters) are really confusing the issue here. Pictureguy is asking a straightforward question, but not a single person has given him a straightforward answer.
I will attempt it. :)

IF the sensitivity specifications of the various models ARE truly identical, then you indeed DO NOT need more power as you go up the line to create the same SPL.
The caveat is the bass frequency capability. That portion of the frequency range is outside the nominal 500Hz range that Magnepan specifies, so for the larger models (which can produce lower frequencies) you do need more power to achieve that capability.

This is a straightforward physics issue and doesn't warrant any subjectivity or any other qualifiers to squishify the conclusion.

Dave.

 

RE: Why More Power?, posted on July 8, 2015 at 15:06:58
Satie
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The measurements from German reviews show the sensitivity falling as you go up the magnepan line. Though the measurements from one of them for a 20.x model were obviously a typo.I am writing from memory so no guaranty...These were not done at the maggie spec freq..

 

RE: Why More Power?, posted on July 9, 2015 at 01:00:15
pictureguy
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If sensitivity does, indeed, drop as you go upline, that's the best reason yet for Magnepan to go to stronger magnets.
And the 20 series is push/pull, too. Doesn't that feature alone help (increase) sensitivity?
Too much is never enough

 

RE: Why More Power?, posted on July 9, 2015 at 05:31:22
Dubious (at best) testing results from those German "reviews." Testing is very challenging for these type of speakers and results easily skewed and misinterpreted.

The best way to think about sensitivity of these is by simple examination of the motor structures. The magnet flux, number of turns passing through that flux, distance of the diaphragm to the magnets, etc, etc. In that aspect, all Magnepans are essentially the same and there is no opportunity for significant sensitivity differences to manifest.

I know the laws of physics have been claimed to have been broken on this forum by various members and their modifications, but it just doesn't work that way.

Dave.

 

RE: Why More Power?, posted on July 9, 2015 at 06:58:14
Satie
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Since the sensitivity is not better but max SPL is better I would say they used their stronger magnetic field to increase the offset (and thus xmax) of the diaphragm and get less distortion at the same spl.

 

RE: Why More Power?, posted on July 9, 2015 at 09:06:06
pictureguy
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I've been thru this entire line of magnet stuff a couple times.
One possible conclusion is that the magnets / gap are the same because MYLAR has such a low
'cooeficient of stretch'. Whatever THAT measure is called.
So it wouldn't be much advantage to have more gap when the mylar won't stretch to fill it.

I've also messed with Ultra-High strength magnets. You can hurt yourself with them via 'pinch'.
And the REAL strong ones will send you to the doctor. They are typically brittle, too. I couldn't imaagine what it takes to assemble a pole piece with such magnets. Keep them well spaced from each other, too!

One question remains, however. How much louder will the RIBBON play than a planar driver? The ribbon WILL benefit from stronger magnets, too.
Problem is making a very sensitive ribbon with a much LESS sensitive panel.
Too much is never enough

 

RE: Why More Power?, posted on July 9, 2015 at 10:41:50
Roger Gustavsson
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My investigations of various Magneplanar bass drivers surprised me. They are almost equally limited in the capability of excursions, even the Tympani IVa. 150-200 W on each driver results in the Mylar hitting the magnets if low frequencies are present that hits the tuning frequencies of the eriver. This will not happen with most "conventional" music but higher SPL can sound a bit compressed. The Tympanis have a similar efficiency to the 3-series. The Tympani bass drivers use thinner wires (half the mass) and lose 3 dB but as the number of drivers is double, the result is -3 +3 = 0 dB.

 

RE: Why More Power?, posted on July 9, 2015 at 10:58:01
What is "power" or the definition of it which you're using? Perhaps you might illustrate your answer by providing a short list of amplifier pairs, in which one is more 'powerful' than the other (and if I'm lucky, how that's determined)?

 

RE: Why More Power?, posted on July 12, 2015 at 23:20:16
pictureguy
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The generally conceded measure for amplifier power is the 'watt'. 1 watt is 1 volt @1 amp.
Certain adjustments need to be made for reactive loads where the VA is more useful and results in a measure called power factor.

You can have different measures, however, based on time limits. 'D' amps, for example, are time limited due to heat sink issues. Some A/B amps will not pass the Stereophile preconitioning period without overheating. Heat Sinks are conceded to be expensive and heavy to ship, and take up more space.

For purposes of this discussion, I'll go with the manufacturers listed 'rms power'.

And since Maggies are GENERALLY a benign, low-reactance load of low sensitivity, I feel fairly safe in using the amplifier manufacturers power rating.

Some interesting things DO pop up when checking further, however. The Pass XA30.5 is rated at 30 watts. However, at redline, fully in A/B mode, it's a LOT more power. Enough more power that I would NOT hesitate for an instant to Biamp my MG1.6s with a PAIR of 'em. Add another (aprox) 3db when going to an active OR passive line level crossover.
I doubt I'd ever make the bias meter even flicker!

Does this help?
Too much is never enough

 

RE: Why More Power?, posted on July 13, 2015 at 09:58:26
Thanks for your reply but unfortunately it's really no help whatsoever. It fails to consider the potential *current* output of an amp, in amps (peak as well as otherwise).

"For purposes of this discussion, I'll go with the manufacturers listed 'rms power'."

Those numbers, and in particular seem useless. I have 200 watt rms rated/ channel stereo amps, some of which cannot succeed in playing Maggies of 4 ohm impedance to minimal sound level without severe distortion (but succeed in easily playing Maggies with 8 ohm impedance to ear shattering levels, without any problem.) Also an Onkyo TX 8511 receiver, rated "100 watts X 2 channels of clean high current power (Crutchfield.com) which can drive Maggies of either 4 or 8 impedance. (Not implying that I ever use that receiver in playing my Tympani IV-As, but OTOH it works in being able to listen to my smaller MMGs. Much of which got this discussion started, e.g. "power" required to play Maggies as one goes up their line in size, e.g., MMGs vs. the 3.7/i.

 

RE: Why More Power?, posted on July 13, 2015 at 11:04:33
pictureguy
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Power is volts times amps. period. Given impedance, and watts, it is a simple ohms law calculation to determine voltage and current.
Now, amplifiers DO have peak current capability. My Parasounds have some factory rating of amps output. Since my hearing is till pretty good, I'm not concerning with that measure. In fact, I doubt there is any agreement among manufacturers about HOW to specify that value. It turns into more mis-information than I'd care to deal with.
Those high currents are at a very low voltage, anyway. That doesn't do me much good though it may indicate a robust power supply.

It is ALSO true that music is NOT rms in nature. By this I mean it is very dynamic and the demand upon the amp is always changing. To this end, I look at rise time and slew rate. It is also a good idea to have some idea of 10khz square wave response.
Taken as a whole, a more complete characterization of an amp gives you a better chance of picking one simply by going with the 'on paper' results.

What you are 'up against' is an amp MAY have good output into 8 ohms but simply FAIL to get it done with lower impedance loads.

8 ohm power may be less than the ideal way to buy an amp for maggies. I'd like to know 4 ohm power as well.
I'm not very concerned with the amps ability to charge a battery or work into highly capacitive or inductive (reactive) loads since panels are a generally reasonable load in those regards.

I had a Rotel RB1070 of 125 or 135 x2 @8 which was utterly incapable of making my Panels work right. NO factory 4 ohm rating, but rather a 'bridged' rating of 330 or so at 8 ohms, which IMPLIES a 4 ohm rating of 165x2. Maybe I just didn't like the sound? I sold it within MONTHS. My bad.

The rule of thumb most Maggie owners go by is the 'double up' rule where a true voltage source amp should (or could?) double up power as impedance 'halves'
I'm not fully on board with THAT either, since you could have an amp with some huge power output which Doesn't double down as impedance halves yet still provide enough juice for your panels.

Here is a link to a 'power cube' measuring scheme. Each amp is tested for voltage output at various impedances and at various PHASE ANGLES. I suspect ANY amp which passes this test with good results should power your panels. The quality of sound, is still up to YOU, however.


Too much is never enough

 

Same thing, posted on July 14, 2015 at 15:16:53
sbrians
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I thought that you were both saying essentially the same thing, but your explanation may be more clear.
Either way, I believe that my 3.3s use much more power than my 1.6s even though I expect that one could apply a 500 Hz sine wave to each and get similar sound levels.

 

RE: Same thing, posted on July 14, 2015 at 20:09:06
TitaniumTroy
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About 7 yrs ago I moved from a small apartment to a small townhouse, with a much bigger living room. 12'5Wx26L with a sloped ceiling 8' to 13'. My 75watt at 8ohms, NAD receiver had no problem powering my MGIIIA's, until I moved. Then I was blowing tweeter fuses at low levels, then the ribbon tweeter itself blew.

I upgraded to triple the power with a 225 watt at 8ohms NAD218THX, problem solved
John Atkinson also measured the NAD's output power on tonebursts, using the Miller Audio Research Amplifier Profiler. Fig.10 show the results with the soft clipping engaged: the increase in THD as the amplifier starts to overload is indeed more gentle than without soft clipping, and massive amounts of power were available with the 1kHz toneburst signal, which is closer to a musical signal than a continuous tone: 247W into 8 ohms (black), which almost doubles to 484W into 4 ohms (red), 950W into 2 ohms (blue), and an astonishing 1555W (green) into a punishing 1 ohm load! Slightly more power was available without soft clipping—305W into 8 ohms, 1575W onto 1 ohm—but again, this is academic.


Read more at http://www.stereophile.com/content/nad-218-thx-power-amplifier-measurements#vsmKFkiMqakWZQ1G.99

 

RE: Same thing, posted on July 14, 2015 at 20:19:53
TitaniumTroy
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You have also have to remember that the True Ribbon Tweeter is not going to be as rugged as quasi-ribbon's. While I was waiting to repair the ribbon tweet, I used my 10.1s. You could only raise the volume so far before they wouldn't just play any louder.

FYI, I have 3 NAD218 THX's for sale, yeah I went a little crazy when the receiver let me down. Looking to upgrade to biamping, and use a Parasound A21 stereo amp for the bottom end. Or
Parasounds JC-1s mono blocks.

 

RE: Same thing, posted on July 14, 2015 at 22:49:46
Satie
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Very competent amp.

My favorite is the 208, predecessor to the 218 I think.

Very good match for maggies at a reasonable price. For some reason I keep forgetting about these two when asked for amp recs.

 

RE: Same thing, posted on July 16, 2015 at 15:40:27
No, Satie is asserting that the Magnepan published specifications of some of the models are incorrect. That may be correct or it may not be. It's a difficult question to answer...IF...the entire frequency range is considered. However, if referring to a single frequency and the speaker measured in a free-field environment, then a consistent (relative) measurement could be achieved.

In your example, if the 500Hz signal level was the same and resulted in the same SPL, then your conclusion that the 3.3's use much more power than 1.6's doesn't make sense.

I don't think it makes much sense to go back and forth on this particular topic. ALL Magnepan speakers are inefficient.....relative to conventional types. :) A db or two here and there between models is irrelevant when the speakers are fully 10-15db less efficient than conventional systems.

Cheers,

Dave.

 

You might even need LESS power, posted on July 20, 2015 at 06:04:36
morricab
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Even if the speakers have the same sensitivity and same impedance at 1 meter their output at 3 or 4 meters will likely favor the larger panel as it will remain more of a line source at greater distances. I always wondered why Maggies are not MORE sensitive as you go up in size because for sure Apogees were. For example a Duetta Signature was both about 2db more sensitive than a Caliper Signature it was ALSO an eaiser load (longer ribbons meant higher impedance).

It is pretty logical because a larger driver will move more air and as long as the force/cm2 is the same then it will be more sensitive. It suggests that for some reason Maggie panels have a lower magnetic field strength per unit area than the smaller ones.

We used to be able to drive Apogee Divas to pretty loud levels with moderate sized amps that would make life hard for the Caliper signature to get the same volume at the same distance.

 

RE: Why More Power?, posted on July 20, 2015 at 06:17:28
morricab
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Both the 1.6 and 3.6 measured by Stereophile showed about 83.5db/watt at 1 meter and around 4 ohms impedance. Assuming you put them in the same size room and sit the same distance away I would say they should be about the same loudness with a slight edge to the bigger 3.6 perhaps for being a better approximation to a true line source.

 

RE: Why More Power?, posted on July 20, 2015 at 11:07:45
Can a given MMG/.7 listener happily using a *minimally* powered amp, one day decide on a 3.7i or 20.7, but continue on using this same *minimally powered amp*, or would a *higher* powered amp be required? (Same listener, same environment.)

One needn't be concerned measuring SPLs and test tone discs, etc. This given listener simply wants to have pleasant listening experiences using their usual wide variety of program material and sound sources. Assume he/she listens to pop, rock, classical and everything else under the sun. (Dealer showrooms exist to demonstrate that - potential customers don't arrive with SPL measuring equipment/test tone sources, unless they want to be 'shown the door'.)

 

RE: Why More Power?, posted on July 20, 2015 at 15:05:56
"Power is volts times amps. period. Given impedance, and watts, it is a simple ohms law calculation to determine voltage and current."

Uh, no. Power is volts times amps ONLY if the phase angle is zero......as in DC circuits.
It gets a little more complicated in AC circuits.
You're on the right track though. :)

The AP testing scenario is a good one because it measures power at various phase angles and dynamic conditions.

Dave.

 

RE: Why More Power?, posted on July 20, 2015 at 15:41:13
pictureguy
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Did I fail to mention Power Factor?

Beyond the scope of necessary answer trying to explain THAT, though when I linked the Power Cube measureing system, you'll get some of that information.
Too much is never enough

 

RE: Why More Power?, posted on July 22, 2015 at 01:28:35
morricab
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I would say yes as long as the room and listening distance stay the same. Move to a bigger room and/or sit much further away and then it might be inadequate.

 

RE: Why More Power?, posted on July 22, 2015 at 07:16:14
"I would say yes as long as the room and listening distance stay the same."

Well, naturally what type test (or experiment) would it be otherwise?
Still however, hearing would be believing.

 

RE: Why More Power?, posted on August 1, 2015 at 13:18:41
Schurkey
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Just a guess: Magnepan expects that you buy larger speakers to go into larger rooms. The power recommendation has AT LEAST as much to do with the (expected) room size as with the specs of the actual speaker model being considered.

I haven't heard an Ohm speaker since I was in college; but I look at the web site now and then. Ohm goes so far as to recommend the cubic foot size of the room to best match with their various models. I'm pretty sure I've seen something similar--but not so specific--on the Magnepan site.

I'm including a link to the Ohm "outlet store" web page, note that one column specifies the cubic foot measurement the speaker is intended for.

 

RE: Why More Power?, posted on August 1, 2015 at 13:56:46
pictureguy
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HSU Subs had a 'sub selector' which primarily went by CUBIC capacity of the intended space.
Too much is never enough

 

RE: 'Power' and Maggies, posted on August 10, 2015 at 08:46:02
pictureguy
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All things being equal, larger drivers SHOULD require more 'work' = energy input to do their 'job'.

However, it would appear that, at least for the panels I originally mentioned, the sensitivity is the same, or so close as to be insignificant. That tells me that the same amp used across the line will produce the same SPL. or very, very close.

That's what started off my quesitoning.
Too much is never enough

 

RE: 'Power' and Maggies, posted on August 10, 2015 at 09:49:02
This work, energy, power scenario is the source of my confusion. It shouldn't come as any surprise that an amp capable of driving a 8 ohm Maggie to window shattering levels can't get a 4 ohm Maggie off the ground. Evidently it did come as a surprise to my dealer (a foremost Maggie dealer, at that) because although knowing my amplifiers and having sold them to me), I was advised to buy Tympani III-Bs rather than III-As. As further evidence of their ignorance one of their service workers was sent to my home to look into the problem. Even he didn't understand what was wrong. It took a call from my dealer to Magnepan to inform them as to what was wrong.

IAE, the listener isn't supposed to understand the 'workings' behind one of their speakers anymore than I'm to understand the workings behind my SUV in order to satisfactorily *drive* it.

 

RE: 'Power' and Maggies, posted on August 10, 2015 at 10:03:39
pictureguy
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Posts: 22597
Location: SoCal
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Some amps which can drive an 8 ohm resistor just fine, do NOT do well at 4 ohms. Like what I understand to be the reality of MOST Home Theater receivers.

Throw in REACTANCE and you are cooked. Even some amps which measure OK as resistance drops fall flat when inductance or capacitance are added, turning resistance into impedance.

I had a Rotel RB1070 of about 135x2 @8ohms and 330 'bridged' into 8. That implied 165x2 @4ohms, but Rotel did NOT list a 4 ohm rating.
Minimal surprise when the amp was utterly incapable of making my panels work well.

Maggies are an EASY load for any competent amp. Most of the line, while certainly of low sensitivity are also of fairly low reactance.

What amp are you talking about that didn't work with your panels?

What did Magnepan tell your dealer?
Too much is never enough

 

RE: 'Power' and Maggies, posted on August 10, 2015 at 16:27:46
I was driving a Tympani 1C with a pair of bridged ARC D76As. For fun I had an ARC EC-2A cross-over and a GAS Ampzilla II which I could toss into the mix, naturally with ARC tubed amps on the top, and the SS Ampzilla on the bottom. The afforded power was more than enough. Going into Tympani IIIAs, and with an ARC EC-4, I would have easily been able to tri-amp them. However my dealer suggested the newer IIIBs and I went along with his advice. None of my amps, and in any combination could drive any panel within a IIIB.

I wasn't party to the conversation between my dealer and Magnepan. (Why do you even think I could/would have been in on it? I let them resolve it as best as they saw fit.)

 

RE: 'Power' and Maggies, posted on August 10, 2015 at 17:38:23
pictureguy
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Posts: 22597
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The Reason? Let's see. My speakers don't work properly with the amps my dealer recommended. So, they talk to the manufacturer of the speaker? Right so far? How could you NOT want to know what the verdict is?
In the end YOU'VE got a bad speaker / amp mismatch, not the dealer OR Magnepan.

What was the crossover point when you used the Ampzilla / D76a combo?

And, is THIS the Ampzilla you had or a newer version? This, the original I guess, had NO 4 ohm rating. So, it's no surprise to find it falling flat into a low impedance load.
The II version was also 200 @8 and I didn't see a 4 ohm for that one, either.

I just looked up another in the LONG line of 'ampzilla' product. The Son Of Ampzilla II is rated at 220x2 into 8ohms and 350x2 into 4ohms. I see NO REASON for THAT version of the AmpZilla to be in the LEAST inadequate when running either side of low sensitivity panels.
Too much is never enough

 

RE: 'Power' and Maggies, posted on August 11, 2015 at 09:13:28
"The Reason? Let's see. My speakers don't work properly with the amps my dealer recommended. So, they talk to the manufacturer of the speaker? Right so far? How could you NOT want to know what the verdict is?
In the end YOU'VE got a bad speaker / amp mismatch, not the dealer OR Magnepan."

You may not be as clever as you think because until 1977 Magneplanar speakers were marketed by ARC, so it seemed a natural to discuss the problem with either Magnepan, ARC, or both. My dealer contacted (either of them?) because he was one of their prime dealers, and selling both of them. Obviously he needed more information, and not solely to accommodate me.

The ARC EC2A (1972-1977) was delivered set to 100Hz, for use with the then Tympani system.

Thanks for the information you found. Nonetheless at one time I owned both the original Bongiorno GAS Ampzilla and an Ampzilla IIi. (Unlike the 'i' in 3.7i, that "i" stood for industrial. By the time of the Ampzilla II's release, Mr. B was no longer associated with GAS.)

Unlike other listeners back then I couldn't hear anything special in driving my Tympani 1Cs using ARC tubed amp products, (e.g. the D-76As), so I had those SS Ampzillas on hand. You needn't inform me as to the 'Zilla's ability to drive any section of a Tympani IIIB. Neither my dealer's installation crew (being part of his service department) nor I found them compatible with the IIIBs sold to me, and he took them back refunding all my costs.

For all I knew during that time, my dealer may not have been completely honest with me. Perhaps he couldn't any longer get his hands on a Tympani III(A), and not wanting to lose a sale he convinced me to purchase the III-B. That was unfortunate because at that time I also had a ARC EC4a (1974-1977) on hand, and the amplifiers useful for tri-amping a Tympani III(A).

 

RE: 'Power' and Maggies, posted on August 11, 2015 at 11:51:13
pictureguy
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Location: SoCal
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Quite aware of the marketing of the Tympani speakers.
I've been a Maggie OWNER for probably about 35 years now, starting with some 'used' MG-1 panels which I found so amazing as to get me to sell my JBL 4311 'clones' from RSL, a SoCal 'boutique' brand of good reputation.

If, as I'm lead to believe the ARC 76a is an 'improved' version of the ARC 75 than No Wonder it wouldn't work WELL with your panels. Even one section. 75 or so a side is very much on the low end while IF the speakers were in an appropriately sized space, that would up the power needed even MORE. After all, my 5000 cubic foot room is ill-shaped and maybe not large enough for such large panels. I MIGHT be ok with 3-series.

100hz Crossover? That is probably around 20%:80% range for required power. BUT, bass has some high power peak demand so I wouldn't count on getting away with such low power on the bottom end.

And Yes, 'rumor has it' that ARC and Maggie go well together. Perhaps some OTHER mitigating factor? Setup? Room condition? Size of room or dimensional ratio? REALLY bad power? Some kind of CABLE or IC issue?

And as a total aside, I friend down here in SoCal, and a poster here on AA, owns a pair of 20s. He Biamps using Emotiva amps on the bottom and tubes on top. And Man, did this sound GOOD. REAL GOOD. I think he uses a Marchand crossover. Also, since the last time I heard 'em, the tubes have been replaced with some SS amps.

And you can BET that if my dealer was talking to the manufacturers of my stuff ABOUT my setup and problems, I'd really WANT to be part of the discussion, even if only at the 'fly on the wall' level.

And I'll stand by what I said. At the END OF THE DAY, no matter WHAT went on with the dealer and Magnepan YOU are the one with the problem.

I know from my experience using a non-4ohm rated amp that I'll NOT be doing that again. Ever. It's not like in that time frame that 4ohm speakers were unknown, either. I think the AR3a was a 4 ohm speaker? And pretty popular at the time.

And of course, your dealer SHOULD have benefitted from such a conversation. No question about it. Even then, I'm sure Magnepan knew things about THEIR panels that others didn't.

So, how'd this all shake out? I think that's the important thing.

Too much is never enough

 

RE: 'Power' and Maggies, posted on August 12, 2015 at 08:54:38
Pictureguy, I wrote in my last post telling how it all shook out:
" Neither my dealer's installation crew (being part of his service department) nor I found them compatible with the IIIBs sold to me, and he took them back refunding all my costs."

(The first above "them" meaning any and all the amplifiers I bought from him.)

Perhaps a bit of a run-on sentence, causing you to miss it.

 

RE: 'Power' and Maggies, posted on August 12, 2015 at 09:20:38
pictureguy
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Posts: 22597
Location: SoCal
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Yes, I read but apparently didn't exactly Comprehend! I've got CRS. Your writing is FINE, especially compared with some folks who have grammar problems compounded by spelling problems in addition to structural issues.

But, what amp DID you end up with? Did you try some other crossover or settings? How about one BIG amp like maybe the Magtech? If I had VERY deep pockets, I'd have a PAIR of Pass Labs XA30.5 with one per speaker.

Just for a point of reference, I OWNED a Rotel RB1070 which proved unable to drive my panels. I than got a PSAudio GCC250 'd' amp (integrated) which took years to become unsuitable. And I went thru MORE setup hassles with my Panels than in the previous 2 1/2 decades TOGETHER. Finally got it ok, but decided to go to a PAIR of Parasound A23 of 200x2 @4ohms. ONE per panel. This is good and allows a Path Forward since I'd love to go to a PLLXO. The P5 'matching' preamp will easily support this idea. And, it's possible to pretty much duplicate the crossover the speaker came with. But on a board which will EASILY fit into an Altoids tin.

I'm glad to hear of another dealer which 'stepped up'. Too bad, too, you went thru such hassles with amp choice. I've owned a bunch of different stuff over the years, too, starting with a Kenwood Integrated a long time ago.
Too much is never enough

 

RE: Why More Power?, posted on August 12, 2015 at 16:23:29
johnvb
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In the case of your Parasounds, Wouldn't going with the A21 give you more "class A" watts, as compared with the A23s? So not really more power, but cleaner power?

Asking cause my speakers (KEF LS50) are said to play nice with Parasounds also, and I have debated whether which model to go with.

 

RE: Why More Power?, posted on August 12, 2015 at 18:13:27
pictureguy
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Yes, that may be true, about the 'A' watts, that is.
I've seen the Parasound folks W/KEF at THENewport where I met Richard Schramm. Real nice guy and we swapped some Chicago Lies. This was a couple years ago when the 'buzz' was all about the LS50, which IS quite nice in the right space.

I use a PAIR of the A23 with my low sensitivity panels.

I think the '23 would be nice but you must consider listening habits, size of space and system goals. I'd LOVE to replace the carbon potentiometer with a stepped attenuator with 1% or better thin film resistors. I'd only need the 6 step switches from GoldPoint. After all, They run 'wide open' now, but I'd like to experiment with SLIGHTLY less apparent gain. I suspect this is NOT a variable gain design, but rather attenuated input which makes it seem so. After all, the '23 retails for about a grand and the '21 goes for double and some change.

Given that the ultimate power is within a Fraction-of-a-DB between a '21 and a pair of the '23, and the proposed (minor) mod to the amp, I suspect you'd NEVER tell the difference. My amps run cool enough that I suspect only 5 to 7 watts into 'A' before 'sliding'.
Too much is never enough

 

RE: Why More Power?, posted on August 13, 2015 at 04:57:17
johnvb
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Posts: 495
Joined: October 26, 2011

The KEFs are a good match for my 180 sq. ft. room, once I added subs. I have an iTube in the chain, and use it's 3D processor circuit to give the system a more "dipole" sound. Not Maggies, but close. :)

Know of at least one LS50 owner over at the AVS forum, that uses the A23 and is very happy. I am assuming that bridging the Parasound amps will degrade the sound quality, have you tried that?

 

RE: Why More Power?, posted on August 13, 2015 at 09:28:05
pictureguy
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Location: SoCal
Joined: October 19, 2008
First, I'm officially JEALOUS of the nice diffusion you have! My room would probably (99%) benefit from a good appllication of sound treatment STARTING with diffusion.

In my brief show listening to the KEFs I was very impressed. Too bad my room is nearly TRIPLE the volume of yours and require a little more 'input'.

180 square feet? That's about 12x15. The MOST important measure is typically omitted from this call-out and that's CEILING HEIGHT. A 10 foot ceiling would give you 1800 cubic feet while an 8 foot ceiling would be 1440 cubic feet. It makes a difference for room modes / nodes.

I officially REALLY like the Parasound stuff. I have a single '23 behind each Maggie 1.6 and run everything thru the newish P5 preamp. The DAC section of the pre is neat, and simplifies TV watching.

Besides a Maggie REFRAME, which is a 'dream project', I'd like 2 other things. 1) Replace the level pots in the amp with a STEPPED ATTENUATOR and 2) Build Passive LL crossovers.
The last? Would net me as much as an additional 3db of headroom and EASILY exceed the (apparent) power of a single A21.
Too much is never enough

 

RE: Why More Power?, posted on August 13, 2015 at 14:29:17
johnvb
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Posts: 495
Joined: October 26, 2011
Yeah, the room is slightly under 12' x 15', with 8' ceiling. The diffusors came from SRL Acoustics, sold as unfinished 2 x 2 Styrofoam pairs. So it was quite a bit of work to get them as they look now. Similar to GIK's Gridfusors.

Just use a couple of digital sources here, so I've been using MiniDSP's NanoDIGI as a speaker to sub crossover and EQ, very happy with it.

 

RE: Why More Power?, posted on August 13, 2015 at 19:45:14
Isn't the sensitivity rating at a specific frequency and not the entire frequency range ?

A speaker that goes lower will need more power.

 

RE: Why More Power?, posted on August 13, 2015 at 20:30:27
pictureguy
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Joined: October 19, 2008
Given what I know about power / frequency distribution, the difference between 35/40 hz of the 1.6-1.7 series and the 5 hz or so lower of a 3 series? A couple PERCENT maybe. Add another slight 'premium' for the 20 series.

I need to mull over the idea of sensitivity measured at a single frequency. I think that implies reasonably FLAT power response? If the speaker were drasticly MORE or LESS sensitive at various frequencies….high OR low, I suspect it would be audible. But maybe I'm just dreaming!
Too much is never enough

 

RE: Why More Power?, posted on August 13, 2015 at 21:40:38
A few points to consider.

1) 25Hz is an entire octave lower than 50Hz.
2) Lower frequencies require more power than higher frequencies.
3) At what frequency were the models rated at ?
4) Physics, does it take more power to start and stop a 400lbs motorcycle or a 2,000lbs car ? Does the weight example equate to square feet of material to be started and stopped ?

 

RE: Why More Power?, posted on August 13, 2015 at 22:44:01
pictureguy
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Posts: 22597
Location: SoCal
Joined: October 19, 2008
The 50:50 power point is close to 350hz. With my panels crossed over at 600, I'm just a little HIGH, but make up for it by low-cutting them at about 50 or 60hz. I'm not a redline guy, so it works out with 200watts per 'way'. Not counting the sub.
Due to real musical content, while the octave from 50hz to 25hz is fairly active, below that? Almost nothing of musical value except for a couple pipe organ notes, one of which is at 16hz and is a MONSTER to reproduce.

Considering that the back emf generated by the mylar moving is returned to the AMP and 'shorted' by very low 'on resistance' I don't see what the question means. I'm not sure how much energy panels store, anyway. My panels have Disc Brakes which work even when wet.

X-over Frequency (Hz) Power to Bass (%) Power to Mid+High (%)
250 40 60
350 50 50
500 60 40
1,200 65 35
3,000 85 15
5,000 90 10

CHART FROM THE ELLIOT SOUND PRODUCTS ARTICLE ON BIAMPING:


Too much is never enough

 

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