Source: Marantz UD7007 universal disc player.
Preamplifier: Marantz AV8805 preamp-processor.
Power Amplifier: Parasound Halo A 52+.
Cables: Kimber AGDL (coaxial digital from source to AV8805), Cardas Hexlink (preamps to power amp), QED Silver Anniversary XT speaker cable, generic IEC power cords.—Thomas J. Norton
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COMMENTS
From the review: "The design's benefits are a largely resistive load, no significant inductance (dome tweeters have an inductive voice-coil that complicates crossover design)..."
From the measurements: "...the phase angle exceeds +40° above 10kHz, presumably due to the inductance of the MPD tweeter's drive system."
Air Motion Transformer tweeters exhibit flat resistive impedance response with respect to frequency in the audible frequency range. Not sure about impedance a decade or two higher.
Look at the data sheets of the Dayton Audio AMT series of tweeters.
http://www.daytonaudio.com/index.php/loudspeaker-components/loudspeaker-drivers-by-series/amt-series.html
That's what the review says.
But the measurements show a significant phase angle in the impedance in the highest frequencies.
That significant phase angle you are mentioning (above 10 Khz) is not the region of the cone upper midrange frequency ........ It is in the MPD ribbon tweeter frequency range :-) .........
My post referenced the tweeter, not the midrange.
I'm not sure what they might be doing in the crossover in the tweeter's filter network to clean up the tweeter's wave guide response, and what they might be letting happen in the ultrasonics to reduce component count. It does seem to exhibit a high Q low pass rolloff in the top octave, the high Q peak providing a little lift and associated rininging, the peak visible in figures 4 and 5. The associated peaking filter in that top octave shows as a sag in the rising impedance curve in figure 1.
edit: It was pointed out to me that JA1's measurements include some resonance present in the top octave in all of his loudspeaker measurements, and that seems to be obfuscating the behavior of the low pass here.
There is a little peak at appox. 16 to 18 Khz region in the frequency response, but it is not anything significant ........ I have seen worse 'oil can resonance' peaks and dips in the frequency response of some metal dome tweeters ....... But those peaks and dips are usually above 20 Khz :-) ......
With exception of a slight psychoacoustic dip in the range of 2kHz to 4.5_kHz, the response appears to be within a few dB of nominal above the baffle edge diffraction step and associated correction.
That is the famous 'BBC dip' in that frequency ....... But that dip is not much in this speaker ....... Usually that dip is purposefully engineered to be -5 db or more :-) .......
Psychoacoustic dip at the link:
https://www.linkwitzlab.com/models.htm#H
Yes .... Your reference mentions the name 'H.D Harwood, BBC research department 1976' ....... Anyway, that dip is popularly known as 'BBC dip' :-) ........
I see a similar response in the datasheets for the drivers you linked to previously from Dayton Audio. I think it's inherent in the driver and not due to any crossover design.
But I don't see any ringing in figure 9. Isn't that little black slice always there in JA's plots and something he has mentioned as being the line rate of his monitor?
...for pointing out the issue of the monitor.
Also, that significant phase angle is not in the crossover region between upper midrange and MPD tweeter, which is 3 Khz :-) .........
Look in the top octave, not the crossover frequency. They are shaping response up there.
True ..... There is significant drop-off of FR, say from above 18 to 19 Khz ....... I don't know whether that makes any significant audible difference ...... Look at the TJN's in-room FR measurements ........ There is a lot of drop-off of the FR in the top octave :-) .........
If the high frequency low pass response exhibits high Q, then the associated peak near the corner of that low pass would provide some lift in the response, and there would be some ringing associated with that.
Note that graphics show eight curves while the keys at the bottom of each identify nine. Regardless that error in identifying curves, the graphics are good enough to show Q affecting peaking and ringing. The brown curves look like textbook 2nd order Butterworth (Q=0.7071) and the yellow curves look like textbook 2nd order Linkwitz-Riley (Q=0.5000).
Source of graphics: https://e2e.ti.com/blogs_/b/analogwire/archive/2015/06/12/is-your-op-amp-filter-ringing-look-at-q
edit: It was pointed out to me that JA1's computer monitor causes a problem that falsely shows some resonance present in the top octave in all of his loudspeaker measurements, and that seems to be obfuscating some of the behavior of the low pass here.
Again, as mentioned above, hasn't JA said that it's an artifact of his video monitor?
I do appreciate that you pointed that out to me, but did not see your comment before this morning. My comment has been edited to reflect that problem associated with the monitor. I would not want to mislead anyone with erroneous observations.
BTW ..... Hi-Fi News has reviewed the Monitor Audio Gold 100 bookshelf/stand-mount speakers (EISA award winner) which probably use similar type of tweeters ....... Hi-Fi News measurements show similar type of peak around 15-16 Khz, with a sharp drop-off of FR above 20 Khz :-) ........
If you want to see how 'oil can resonance' looks like (which I mentioned above), see the Hi-Fi News measurements of KEF R11 (EISA award winner) ......... But, those peaks and dips are way above 20 Khz ...... KEF is one of the companies, which uses Aluminum domes for tweeters :-) ........
Another example ...... There seems to be some type of filter being used for high frequency roll-off for the GoldenEar speakers ....... GoldenEar also uses ribbon tweeters ....... Look at the FR measurements of GoldeEar Triton Reference by Hi-Fi News ......... There is a sharp drop-off of FR above 20 Khz :-) ........
Here comes the 'king' of all FR measurements ......... See Hi-Fi News measurements of Dali Callisto 6C ...... Nice 'BBC dip' in the presence region and a sharp drop-off above 20 Khz ...... Very 'dramatic' FR :-) ........
Interestingly TJN used +1 db boost in the treble frequency :-) .......
Its a subjective choice in voicing the crossover.
Goes to show the usefulness of tone controls/EQ :-) ........
Al₂O₃ aluminum oxide, aka Corundum, aka Alumina ceramic, and in single crystal natural gemstone or synthetic is Ruby and Sapphire.
Al₂O₃ is also the surface coating result of aluminum anodization.
https://sundoc.bibliothek.uni-halle.de/diss-online/04/04H055/t2.pdf
MIL-A-8625
Type I chromic acid anodizing
Type II sulphuric acid anodizing
Type III sulphuric acid hard anodizing
There are processes that can produce a significantly thicker anodize, and some might refer to that as ceramic coating. It probably sells better than anodized aluminum. The Alumina ceramic is more rigid and more brittle than the aluminum substrate. It is more difficult to get a consistent thick layer of Alumina on a thin substrate of aluminum of a controlled shape without breaking the resulting item, because it can be fragile. Ask anybody who suffered through breaking an Accuton diaphragm, not inexpensive.
https://accuton.com/en-home/produkte/lautsprecher/keramik
Revel is one example company, which uses DCC (deep ceramic composite) Aluminum cones :-) ........
Additional note ........ The Beryllium dome tweeters used in Revel speakers show almost flat frequency response to 20 Khz :-) ........
Time for Stereophile review of Polk Audio Legend L800 floor-standing speakers, with SDA technology ..... About in the same price range, $6,000/pair ....... See S&V review :-) .......
I don’t understand the above commenters, seemingly trying to show their knowledge of test results and exhibiting blatant, ‘I know better than you’ statements. Such pedantry is boring. Just listen to the music!!
These "Monitor Audio Gold 300" speakers look markedly different than those being sold by Crutchfield. Does MA reuse model names for multiple generations of speakers?
Example:
https://www.crutchfield.com/p_893G300PB/Monitor-Audio-Gold-300-Piano-Black.html?cc=07&tp=185
Just wondering. Thanks!
The model under review here is the 5th generation of Monitor Audio's Gold series, so it's sometimes referred to as the Gold 300 5G.
The one in your Crutchfield link is the previous generation Gold 300 (although it was just known as the Gold 300, not the Gold 300 4G).
Usually Monitor Audio doesn't reuse model names for multiple generations of speakers. But in this case, they sort of did.
I have been auditioning the Gold 300 and Silver 500 7G and I am struggling to justify the price delta. As pointed out at almost 3X the price it is not even double the performance. The strength of the Gold is the tweeter. I have spent hours going back and forth and on some track the Silver 500 seems to have tighter bass vs. the Gold being a tad more laid back. The Gold tweeter is amazing and strings are just so lifelike. the silver highs are a tad bright, maybe just becasue the Gold is so neutral. Most of the cost is the better cabinet with more reinforcement, but again, not sure it justifies 3X the cost. I would have zero hesitation if they dropped the mid/tweeter from the Gold in the Silver 500 and called it a Silver 700 and added $1K per speaker and I would pay it, but the difference in US is 3X which I can't really justify.
I had auditioned these 3 times against Silver 500 7G and these are more refined with higher end due to the ribbon. Here in the US they are just too darn expensive. Here the Gold run about 3X the Silver 500 and most of that I am sure is the beefier cabinet and materials in the cabinet. I just can't bring myself to spend this much as much as I love their sound.
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