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Measurements on 1.7, 3.7 and 20.7

83.226.135.246
Posted on September 25, 2014 at 08:58:16
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 I have found some german reviews of 1.7, 3.7 and 20.7. There are also measurements!

http://www.forumbilder.se/DE275/mg-1-7-review.jpg
http://www.forumbilder.se/DE275/mg-3-7-review.jpg
http://www.forumbilder.se/DE275/untitledmg-20-7.jpg

Interesting to see that the 3.7 is reported to have its low frequency cut-off at 27 Hz (-3 dB)! Maybe a misprint? I expected it to be between the 1.7 and 20.7. The 20.7 at 33 Hz and the 1.7 at 37 Hz. Extremely flat impedance for 3.7 and 20.7. Very low effiency for the 20.7.

 

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RE: Measurements on 1.7, 3.7 and 20.7, posted on September 25, 2014 at 13:56:08
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Note the flat impedance, small phase and excellent impulse response for the 20.7. The FR also looks good with minimal bass droop.

Similarly with the 3.7, obviously the bass cuttoff is 37 hz not 27.

The sensitivity on the 3.7 is bad at 83 db. but absolutely abysmal at 77 db for the 20.7. That leaves you with only a handful of high power amps that can drive it into the edges of its performance envelope. The new Emotiva XPR monos being one option.

 

1,750 watts into 4 Ohms? Yup, that would do it!, posted on September 25, 2014 at 15:08:21
sd
Audiophile

Posts: 117
Location: No Cal
Joined: April 19, 2010
 Has anyone tried a pair of these Emotiva XPR's on some 20.7's? I would think that they might be in line with the Bryston 28B beast, but I have not read any reviews.
SD

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 25, 2014 at 15:45:39
Davey
 Magnepan's quoted sensitivity for the 3.7 and 20.7 is the same. So, either Magnepan has their specifications horribly wrong or the testing scenario from the German article is highly suspect. I would bet money on the latter. :)

The 20.7 impulse response also looks highly suspect to me. I can't make out the graphing marks but it doesn't appear the resolution is very high.

Dave.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 25, 2014 at 15:57:32
Potrzebie
 The sensitivity (efficiency) is the same for all Magnepans.

I just do not understand the recommendations, of evermore higher power amps, for the more expensive models. Do users playback the more expensive model at higher SPL's ? Do they just like bigger power amps ?

Makes no scientific sense IMO.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 25, 2014 at 16:12:27
neolith
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Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 The low sensitivity is not as bad as it seems. Stating the obvious, these are planar speakers and the fall off is proportional to the distance unlike point source speakers where the fall off varies with the square of the distance. Off-hand I would have expected the sensitivity of the 20's to be higher because of the push-pull magnets -- so much for common sense. Regardless Maggies like "kick sand in your face" Charles Atlas amplifiers.



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 25, 2014 at 17:37:44
Davey
 Just because the sensitivity is the same doesn't mean the SPL capability is. The larger ones will obviously play louder with more power...all other things being equal. This should be an easily understood concept.

Dave.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 25, 2014 at 18:07:22
Potrzebie
 The sensitivity is the output ( SPL) at a stated voltage in (watts into 4 ohms), at a certain frequency (usually 1KHz).

If the frequency response is flat within the normal listening range, the SPL will be the same for the same watts in, for every Magnepan model.

That is common sense!

Did you take high school physics or are you just stupid?

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 25, 2014 at 18:57:37
Davey
 You better read my post again.....carefully this time.

Dave.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 25, 2014 at 19:07:37
russ69
Audiophile

Posts: 951
Joined: December 13, 2009
 "Did you take high school physics or are you just stupid?"

High school physics were easy, I got more stupid in college.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 25, 2014 at 20:08:37
Davey
 Nah, I don't believe you. You might have done some stupid things in college, but you weren't more stupid. :)

Back on topic.....we can even put some estimated numbers on the relative differences.
If we assume the excursion capability is equal, the 1.7's are 442 square inches and the 20.7's 800 square inches. (The bass driver determining the overall SPL capability.)
SPL difference equals 20 * log(442/800) meaning the 20.7's can play fully 5db louder than the 1.7's. That's a lot!
And here's a quiz for Potzrebie.....since we assume the sensitivity is the same, how much more power will it require from the amplifier to yield that 5db increase in SPL??

Cheers,

Dave.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 26, 2014 at 00:13:29
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 It is shown in the window between 3.5 and 4 msec. The start is something like 3.65 msec and the peak is at about 3.7 msec just left of center between the marks and the counter peak is just to the left of center at say 3.8 msec.

For comparison, here is the response for the Thiel 3.7 from Stereophile.

The scale is actually finer in the German audio rag.

It is entirely believable if you take what someone had measured here using his DEQX'ed maggies, which looked much the same. Damn quick speaker if the XO is done right.

Sensitivity measurements may have been done correctly with the 3.7 and too close with the 20.7 but the sensitivity is low in any case. If you use the measurement as if it were taken at 3m and back calculate to 1m using the linear drop assumption (rather than square) then you might have 82db ? That is one way to measure large planars for comparison to boxes.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 26, 2014 at 01:04:36
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 These german tests does have a few faults, as there use to be about Magnepan speakers. The lowered moving mass etc. is really not there. Everyone seems to think the mass is lower for the foil conductor... The effiency is often measured in a more or less anechoic room and at 1 m. For large dipole speakers it is better to measure them at 3 m or even more. In these cases they prefered the speakers directed at the listning posistion. No wonder, as the frequency response off-axis is far from even. Frequency response measurements may also better be done in the listening room, like Stereoplay use to do, http://www.forumbilder.se/DE2A1/quad-20esl-20989-20measurement-1.jpg Sure the measurement on the right is closer to what the Quad ESL 989 sound like?

Comparing just the size of the Mylar in the 1.7 and the 20.7 may not be correct. You need to know the tuning too. The larger area of the 20.7 bass driver will have to go lower. The lower resonant frequency use to have a very large peak reducing the maximum excursion of the diaphragm.

I also have some measurements of the MG II, 1.5, 3.5, 3.6, Tympani IV and IVa. Also some Apogees like Duetta, Fullrange, Diva, Caliper of different generations.

For those of you reading german, I have scanned most of these reviews. Let me know if you want them.

Do you know why the http://www.twin-x.com/groupdiy/ is down?

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 26, 2014 at 06:36:16
Davey
 I understand that different absolute sensitivity measuring techniques (other than a simple 1 meter measurement) might be more appropriate for Magnepan speakers, but I am only interested in the (German measured) 'relative' differences between models. It seems to me the German tests are showing different measuring technique when evaluating these models. That should have been explained in their testing. A 6db difference in sensitivity is a huge difference. :)

Dave.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 26, 2014 at 06:42:45
Davey
 Does the data point spacing look consistent to you? There's something wrong with that impulse response, but I can't identify the exact issue without more information.

I question your "damn quick speaker" comment, but that's a subjective evaluation so can't argue with. Relative to conventional speakers which most likely use motor structures with much more power, Magnepan's do not have excellent impulse response. Much stored energy and ringing is noted with proper testing. However, that doesn't necessarily relate to a less than enjoyable listening experience, as has been noted by satisfied users for years. Objective testing is not where Magnepan's excel. :)

Dave.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 26, 2014 at 07:36:49
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 I have compared the effiency of my MG 3.6 to a pair of conventional box speakers with a known effiency. I get about 5 dB difference at the listening position, 82 dB refered to 1 m.

 

Greater than 3x (3.16 2b exact) , posted on September 26, 2014 at 10:20:47
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 Did I pass?



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 26, 2014 at 10:28:25
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I was thinking in terms of the settling back to 0. That makes it quick. I know that planars often have more ringing/resonances with transverse waves, and yes, the maggies have a lowish force/mass, but it looks good on this impulse test and the drivers have good impulse behavior on their own (without XO issues). The Neo drivers are better in this regard. The 20,7 also is supposed to have a thinner midrange diaphragm IIRC. I said damn quick because of the test. That is what I take from it.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 26, 2014 at 10:40:21
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
I think they used up the doubling of the magnets by increasing air resistance from the second perforated plate and increasing the depth of the gap(s) to allow greater xmax. Besides, magnepan's philosophy is that the higher the cost of the speaker so is the importance of sensitivity is reduced since "power is cheap" at least relatively.

 

Semantics, posted on September 26, 2014 at 14:45:36
neolith
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Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 Before you and Davey come to blows, let's be sure everyone is on the same page. There is a lot of confusion among lay people and Audiophiles alike about the terms used to describe sound. Remember loudness is subjective and while related to intensity and SPL it is affected by human preception as well as duration of the sound and other factors.
While all Maggies may have the same sensitivity (I am not sure I agree with that), the maximum SPL differ. That's why the 20's can energize a larger space than the SMGa's.
Here are two references to clarify the terms used to describe sound:
Reference 1
Reference 2



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: Semantics, posted on September 26, 2014 at 17:00:32
Davey
 There's no semantics here. :)

SPL ratings are generally assumed to be free-field so it's generally accepted that sensitivity and SPL are directly related. So, if all Magnepan's have the same sensitivity then they all produce the same SPL at the 2 meter distance......at a given input.....in the free-field.

The point I am making here (that went completely over Potrzebie's head) is that the larger models CAN produce larger SPL's than the smaller models. It's common sense, you have a larger radiating area, you can move more air, but, you need more power to do it.

Cheers,

Dave.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 26, 2014 at 17:03:55
Davey
 That seems reasonable for a comparison to a conventional speaker.

However, I was referring to relative sensitivity differences of the Magnepan models quoted in the German tests and noted by Satie. A 6db difference there is considerable and there must be some explanation for it.

Cheers,

Dave.

 

RE: Semantics, posted on September 27, 2014 at 15:17:46
Potrzebie
 The larger Magnepans may be capable of higher SPL's (they handle more power) than the smaller ones, BUT NOT AT THE SAME WATTS IN!

The larger panel just means lower bass and more resolution, at the same SPL.

That went over your head!

 

RE: Greater than 3x (3.16 2b exact) , posted on September 27, 2014 at 18:39:10
Davey
 Yep. But I knew you knew the answer. :)

IIRC, this exact topic was discussed on this forum about ten years ago. Actually, pretty much every topic has already been discussed years earlier. This is an interesting forum. :)

Dave.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 27, 2014 at 19:51:55
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I am not going to say that the actual sensitivity is 77 db and change, but I know from listening that it is lower. We compared them in the same setup and position with the same equipment and they produced lower volume but more substantial bass. When the dealer was done setting up the 20.1 (was a new model then) he set the vol. at 59 on the preamp which is the volume we were listening to with the 3.5 (IIRC) later I found mysef listening at 63 most of the time, but that was louder than how I played the 3.5. So I would guess that the sensitivity difference is something like 2 db. Could be as low as 1 db difference, but I don't think I would have picked up on that small a difference so readily.

 

RE: Semantics, posted on September 27, 2014 at 19:58:04
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 It is not semantics and each step up the price ladder in maggies leads to less sensitivity, as they increase the gap as they go up in price and active surface area. The SMG and later MMG are the most sensitive, Tympani and MG20.x least sensitive.

 

RE: Semantics, posted on September 27, 2014 at 20:58:05
Davey
 So, the Magnepan advertised (all the same sensitivity) sensitivity ratings for the various models are incorrect then?
And it seems like (at least a couple of) the German test report sensitivity ratings are way off the mark?

Dave.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 27, 2014 at 21:55:32
Davey
 In case you fellas haven't deduced this yet, I'm asking these devil's advocate questions to try and help you understand how difficult it is to characterize and measure these speakers.....for the German guys.....and even for Magnepan.

You don't mention whether the numerical readings on your preamp correspond to relative db levels. So, there's yet another confusing data point. :)

Dave.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 27, 2014 at 22:50:15
pictureguy
Audiophile

Posts: 22597
Location: SoCal
Joined: October 19, 2008
 I don't see HOW the mass of the QR driver is less than the SAME driver in non-QR format.
IF the DCR of the drivers is the same, and the length of the serpentine is the same, than I'd say they used the SAME amount of wire per inch or CM. Just 'mash' it flat and you've changed from wire to QR.
Based on using LESS glue for the QR, and perhaps NO overcoat, you May get a few grams less weight for the QR driver, but measuring the material used, the difference should quickly be shown to be the glue / adhesives, NOT the wire/QR or mylar. That is, if my assumptions about serpentine length and DCR are correct.
Too much is never enough

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 27, 2014 at 22:59:19
pictureguy
Audiophile

Posts: 22597
Location: SoCal
Joined: October 19, 2008
 I'd figure some way to Biamp the 20.7 with a QUAD of JC-1 or perhaps a PAIR of Magtech. Than call the electrician out to install a 20 amp service x2…..one for each amp or amp-pair.
Too much is never enough

 

RE: Semantics, posted on September 28, 2014 at 01:36:31
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Go try it yourself, but at least subjectively that seems to be the case. As to whether at a certain frequency they might all be within 1 or 2 db from each other is a possibility. Sensitivity ratings for speakers are a sensitive issue for manufacturers.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 28, 2014 at 01:48:39
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Unfortunately they don't make that easy with the 20.7, but go to your dealer and try it out with the same electronics and see the difference between a small maggie and a big one. I think it is a sensible approach and it is not much of an issue to make the claim that they all have the same sensitivity rating. In the bulk of measurements in S'phile the speakers come in short of their sensitivity ratings - sometimes seriously so.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 28, 2014 at 05:58:29
neolith
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Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 If you are willing to open your 20.7's and sketch out the wiring with the values of the caps, coils and speaker resistances (you can get a cheap LCR meter for around $30), I will come up with an equivalent parallel crossover and its active line-level equivalent.



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: Semantics, posted on September 28, 2014 at 07:05:50
Davey
 I have tried it myself. Not with X.7 speakers, but with MMG, 1.6, and 3.3 models.

Magnepan's sensitivity specifications are well defined at 500Hz with a two watt input. That's an advertised specification that shouldn't be sensitive, or subject to subjective evaluation, or even frequency response. :)

I'm still looking for an explanation of the huge 6db difference (83db...77db) between the 3.7 and 20.7 (respectively) that you noted in the German tests. You seemed to accept that relative difference and commented that only a handful of power amps can drive the 20.7. Now you're backing away from that conclusion and seem to indicate they might be within 1-2db in sensitivity.

Dave.

 

RE: Semantics, posted on September 28, 2014 at 09:12:24
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I am not taking the position that the 20.7 measurements in the German (stereoplay?) are correct. I believe that something is wrong there. Just that I can't know what without asking them.

I should perhaps have added a "if you believe they are correct then" qualifier.

As far as my own experience then 1-2 db was what I expected to see in the measurements. I see from their FR plots that the bass resonance does not show, which probably indicates a far field measurement If they were smart enough to do that for the FR then I would expect they did so for the sensitivity measurements, in which case they would have used some assumption to back calculate the representative figure for 1 m. My best guess - and that is all it is -- would be that the 77 figure is not back caculated while the one for the 3.7 was.

That said, "only a handful of high power amps" is still the case for an 82 db speaker. At least if you want to be able to reach the top capacity of the speaker to produce output.

As far as the spec. from magnepan - I think the choice of freq speaks for itself.

So in your own experience comparing those speaker models what did you observe?

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 28, 2014 at 09:25:33
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I can't afford the white goods from Boulder. The blue flourescent display was on the dealer's preamp. Those are usually in 1 db increments. But I don't know that was the case, I never asked.

 

RE: Semantics, posted on September 28, 2014 at 10:06:07
Davey
 The inherent sensitivity of all the Magnepan models is the same. This is primarily the result of the motor structure.
The magnets are the same, the distance from xducer to magnets is the same, the pitch of the transducer wires is the same, etc, etc. Thus, you have virtually the same amount of conductors cutting the magnetic lines of force in all the models. There's just no way to create significant transducer sensitivity differences in these models.

That's why the 6db relative difference measurement caught my eye in the German testing. Obviously it's an error in their testing, or arithmetic, or something else with the 20.7 system.

I think your subjective evaluation of the sensitivity differences is probably pretty good.

Cheers,

Dave.

 

RE: Semantics, posted on September 28, 2014 at 11:07:29
Davey
 In case you haven't noticed, I write my posts (on purpose) in a way that forces members to read them carefully. :)
Don't feel too bad....you're not the only who doesn't read them carefully. :)

Cheers,

Dave.

 

RE: Semantics, posted on September 28, 2014 at 21:59:08
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I don't know that the distance between the voice coil and the magnets is the same on all maggies. It is definitely greater in the 20.x models. I suspect that was the case with the T-4 bass panels and midrange vs the III/A. It isn't easy to measure with accuracy with simple tools (micrometer) but it appeared so with the T-4 and 4A vs MGIII and later 3.3. the SMG appeared to have a really small offset in comparison. But these are finger touch observations, not measurements. It is easy enough to do in manufacture so it would not be an issue to implement.

Bottom line is that I don't know either way but strongly suspect that they are different. Definitely so in the MG20.x.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 29, 2014 at 04:56:44
morricab
Distributor or Rep

Posts: 9176
Location: switzerland
Joined: April 1, 2005
 And by using a cheap high powered amp be guaranteed to never hear what the speaker is capable of sonically just to pursue high volume listening...

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 29, 2014 at 06:50:11
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 That is the problem you can solve with biamping. Though it persists with a low sensitivity midrange and tweeters that require over 100W for some listeners such as myself.
If you want to use a high quality amp with limited output on the upper end then you can replace the midrange in a large maggie with a line array of Neo8 or Neo10 drivers. The ribbon tweeter is more sensitive than the bass and mid. On the 20.x models you need to build a new frame for the Neo drivers and tweeter to accommodate them and to separate them physically from the bass, creating a two panel speaker.

 

RE: Semantics, posted on September 29, 2014 at 06:57:07
Davey
 I think we're beating a dead horse. :)

The Tympani's are a long obsolete model, different scheme, and have a considerably different sensitivity rating from Magnepan. Those are spec'd at 87db at 1 watt. That's fully 4db higher than the X.7 models or most other "standard" models.

The push/pull 20.7 is quoted from Magnepan as exactly the same sensitivity as the 1.7/3.7 at 83db. Your subjective evaluation says otherwise. I'm fine with that. :)
However, it seems the 77db sensitivity quoted by the German test is way out in left field and incorrect?

Dave.

 

RE: Semantics, posted on September 29, 2014 at 10:32:54
Roger Gustavsson
Audiophile

Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 I think Magnepan speakers have sensitivity rating calculated "backwards" to 1 m. It is not a very good idea to measure them at 1 m, far better at 3 m or even more. When I compared with a conventional pair of speakers at my listening position (as mentioned earlier), I recorded a difference of 5 dB at a distance of 4 m to the 3.6. My conventional speakers are rated for 86-87 dB/m (real world numbers) and impedance is the same as the 3.6. The low rating for the 20.7 is really strangre but most reviews have no measurements at all.

I have also looked at the various Magnepan I have. There are partly different magnets and the distance to the conductors on the Mylar is also different. The differencies are small but they are there. Some speakers use heavier conductors, the old Tympani IIIA and the 3-series. The Tympani IVa has lighter conductors but as far as I can measure thicker magnets and spacers. Tympani IVa mids has curved back plates (allow for greater excursion), thinner Mylar and the diaphragm is partioned in smaller areas, low moving mass of these for sure.

 

RE: Semantics, posted on September 29, 2014 at 12:09:54
Davey
 Yeah, I can understand that the Magnepan sensitivity specifications would be extrapolated from a longer distance measurement. But you transition from the far-field to the near-field when doing that for most of the models. :)

I would feel better if Magnepan didn't publish sensitivity ratings for their speakers. It just creates more confusion than it solves for many users. :)

Cheers,

Dave.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on September 29, 2014 at 13:05:24
klao
Audiophile

Posts: 105
Location: Thailand
Joined: March 15, 2008
 Found a link to the full review of the 20.7's. I'm not sure if it's a legal one, if not Admin please delete. :)

http://www.bm.rs/Magnepan/Magnepan%2020-7%20-%20Stereo%20July%202014.pdf

 

RE: Semantics, posted on September 29, 2014 at 14:51:03
Satie
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Posts: 5426
Joined: July 6, 2002
 Yes, the horse is long dead but I am very curious to get a definitive answer on the standoffs for the various models.

The T IVa sensitivity spec is, shall we say, "in doubt". I don't have actual measurements but the T IV was not an 87 db speaker. The bass panels are 85 db raw (without the XO) so long as you don't reach levels where they compress. 85 db would be a very generous figure for the whole speaker (or actually the mids).

 

RE: Semantics, posted on September 29, 2014 at 15:51:53
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Considering the difficulty of doing a "real" standard measurement, I think what they are doing is fine. The figure is a useful representation of output vs. power in the standard form we expect to see in a test or spec, even if it is a bit of an embellishment.

 

RE: Semantics, posted on September 29, 2014 at 22:12:27
Roger Gustavsson
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Posts: 2055
Location: Huskvarna
Joined: February 12, 2010
 Stereoplay measured the Tympani IVa. http://www.forumbilder.se/DE2MF/tympani-20iva.jpg
It was found to be 3 dB more efficient than the Infinity RS1. 84 dB/W/m. Compression begins at 103 dB for both in the range 40-400 Hz.

 

Power Amps , posted on September 30, 2014 at 07:51:22
BigguyinATL
Manufacturer

Posts: 3475
Joined: April 10, 2002
 Lots of crown high power amps can do them justice - many with build in DSP crossovers and room eq available. They also work great with lesser Maggies. One of the nice things about a planar driver with side by side woofer and tweeter is it is pretty easy to orient the microphone in a way to get the perfect time alignment.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius

 

RE: Semantics, posted on September 30, 2014 at 13:31:39
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Thanks Roger, also thanks for the scattered details on the differences in magnets wire/foil and spacer dimensions. If it isn't too much of an effort could you point to what models had which structural aspect?

I am thankful that someone stepped in with his observations of the differences, for a minute there I was thinking I may have been "seeing things" for 30+ years.

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on October 1, 2014 at 19:53:31
A.Wayne
Audiophile

Posts: 2527
Location: Front row center
Joined: November 30, 2011
 Sensitivity and efficiency are two different things and no , they are not the same for all maggies ...

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on October 2, 2014 at 17:03:45
Potrzebie
 YOU ARE WRONG!

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on October 3, 2014 at 09:32:14
Davey
 There's been confusion about this for years. A. Wayne is not incorrect, but it's not a black and white issue and the subject is more interesting than it might seem.

If you're interested in doing a little learning between shouting down members, you might read John Atkinson's article from 1997. I disagree with John on certain things, but generally he has an excellent understanding and explains things well. But, there are many other references/authors as well.

Here's a link to the appropriate page, but you should read the whole article:

http://www.stereophile.com/content/measuring-loudspeakers-part-one-page-3

Cheers,

Dave.

 

John Atkinson's speaker measurements are always bogus IMO! nt, posted on October 3, 2014 at 16:05:28
Potrzebie
 nt

 

RE: Measurements on 1.7, 3.7 and 20.7, posted on October 6, 2014 at 09:27:29
A.Wayne
Audiophile

Posts: 2527
Location: Front row center
Joined: November 30, 2011
 Potrzebie,

Hard to dispute such a highly technical response, will concede ,,,,

Regards

 

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