I really appreciate the advice. I’m going to give them more burn-in time and see.
As a different perspective -I can't honestly say I have any difficulty with it at all myself in that sense, although I'm not 100% on what's meant by 'poor bass sharpness'.
For whatever it's worth, below its 191Hz mass-corner, & ignoring the room, bass performance is dominated by the electromechanical characteristics usually broken down as T/S parameters, in combination with the chosen enclosure type & alignment. As far as T/S values go, there's nothing at all unusual about MA-200M: it's an 8in drive unit with a relatively low Fs, a middling Vas for a contemporary driver and a Qt toward the lower end of what would be considered middling [ditto]; it's certainly relatively well-damped electrically, with a decent but not excessive amount of mechanical. These values were actually largely driven by me, after reviewing 16 of the most popular 8in midbass drivers on the market in roughly its price bracket. As far as enclosure alignments go -that's down to the builder. We've provided a variety of simple[ish] examples on the site to help with that, but we can't cover all bases of course, just hope to do most of the main ones & a few more exotics, for grins.
Above the mass corner frequency, we're in the nominal mass-controlled / flat BW, although like most MA units [and many wideband drivers in general] it transitions to resonant / TL operation well before it reaches the nominal piston limit or the VC point source frequency -since it's a curvilnear alloy cone with a very flat profile it's almost inevitable as you can't easily decouple without physical breaks or additions, which is a whole separate set of design parameters. But that's arguably a separate issue since it affects the driver whether it's run as a woofer, midbass, fullrange, mid-tweet, midrange or whatever.
For whatever it's worth, below its 191Hz mass-corner, & ignoring the room, bass performance is dominated by the electromechanical characteristics usually broken down as T/S parameters, in combination with the chosen enclosure type & alignment. As far as T/S values go, there's nothing at all unusual about MA-200M: it's an 8in drive unit with a relatively low Fs, a middling Vas for a contemporary driver and a Qt toward the lower end of what would be considered middling [ditto]; it's certainly relatively well-damped electrically, with a decent but not excessive amount of mechanical. These values were actually largely driven by me, after reviewing 16 of the most popular 8in midbass drivers on the market in roughly its price bracket. As far as enclosure alignments go -that's down to the builder. We've provided a variety of simple[ish] examples on the site to help with that, but we can't cover all bases of course, just hope to do most of the main ones & a few more exotics, for grins.
Above the mass corner frequency, we're in the nominal mass-controlled / flat BW, although like most MA units [and many wideband drivers in general] it transitions to resonant / TL operation well before it reaches the nominal piston limit or the VC point source frequency -since it's a curvilnear alloy cone with a very flat profile it's almost inevitable as you can't easily decouple without physical breaks or additions, which is a whole separate set of design parameters. But that's arguably a separate issue since it affects the driver whether it's run as a woofer, midbass, fullrange, mid-tweet, midrange or whatever.
Scottmoose:
So, can it be used as a woofer? 30-liter enclosure is good enough? does it need 300 hrs break-in time?
Thank you for your advice
So, can it be used as a woofer? 30-liter enclosure is good enough? does it need 300 hrs break-in time?
Thank you for your advice
Of course it can -or a midbass anyway: depends how you term a woofer. As for 'good enough', that's going to vary with what you're trying to do & what your target alignment happens to be. 30 litres is about 5 more than a pi-align [well-damped] pro audio vented alignment, and about 11 less than what I described as a medium-sized vented for this unit. Assuming you tune it well, it should be fine, if you want a relatively well damped alignment.
300hrs? If you run them very gently, yes. Which is typically a good idea: Captain Caveman tactics work fine for pro drivers, but for something a bit more refined, a little finesse never goes amiss 😉
300hrs? If you run them very gently, yes. Which is typically a good idea: Captain Caveman tactics work fine for pro drivers, but for something a bit more refined, a little finesse never goes amiss 😉
The English translation is 'poor bass sharpness', but it's difficult to convey the true meaning in words.
I think 'air recording' is more suitable than 'text' to convey what I listened and felt.
These are comparisons with the same music and the same enclosure.
MarkAudio MA200-M
MarkAudio CHR120
Visaton BG20
SB Acoustics SB20FRPC30-8
TangBand W8-1772
I think 'air recording' is more suitable than 'text' to convey what I listened and felt.
These are comparisons with the same music and the same enclosure.
MarkAudio MA200-M
MarkAudio CHR120
Visaton BG20
SB Acoustics SB20FRPC30-8
TangBand W8-1772
If it's the same enclosure, then the alignment will change between drive units unless Fs, Vas and Qt are identical in all cases. If they're not, then it needs to be redesigned / optimised in each case to ensure they are all tracking the same alignment, otherwise all you're really doing is hearing differences in that, not the driver as such. That's certainly the case here:
MA200M
Fs = 33Hz
Qts = 0.346
Vas = 65.2 litres
CHR-120
Fs = 34.25Hz
Qts = 0.372
Vas = 58.9 litres
Visaton BG20
Fs = 38Hz
Qts = 0.44
Vas = 110 litres
SB20FRPC30-8
Fs = 39.4Hz
Qts = 0.45
Vas = 66.3 litres
W8-1772
Fs = 45Hz
Qts = 0.27
Vas = 94.45
So there are some major variations in relevant parameters for box loading there -these units need different box volumes / tunings / loadings & if used in the same enclosure they will automatically have very different alignments: in that case, what you hear in the LF is going to be completely dominated by those (sometimes dramatic) differences in system alignment, rather than necessarily a characteristic of the driver itself. The only time you can really eliminate this is on a very large baffle, or an enclosure so large that Vb swamps the Vas, Qt requirements.
MA200M
Fs = 33Hz
Qts = 0.346
Vas = 65.2 litres
CHR-120
Fs = 34.25Hz
Qts = 0.372
Vas = 58.9 litres
Visaton BG20
Fs = 38Hz
Qts = 0.44
Vas = 110 litres
SB20FRPC30-8
Fs = 39.4Hz
Qts = 0.45
Vas = 66.3 litres
W8-1772
Fs = 45Hz
Qts = 0.27
Vas = 94.45
So there are some major variations in relevant parameters for box loading there -these units need different box volumes / tunings / loadings & if used in the same enclosure they will automatically have very different alignments: in that case, what you hear in the LF is going to be completely dominated by those (sometimes dramatic) differences in system alignment, rather than necessarily a characteristic of the driver itself. The only time you can really eliminate this is on a very large baffle, or an enclosure so large that Vb swamps the Vas, Qt requirements.
Hi Scott.
Yes, it is important to design the box to fit the driver.
The actual measured values (fs, Qts) of my MA200-M are close to BG-20 and SB20FRPC30-8.
There is a 13%-14% error from the manufacturer's published values.
I think it is not a bad match with DDVP-20.
Aha! That would fit better what I heard (at ~30hr).
Not able to youtube... but still would like to decipher "poor bass sharpness" -- slow impulse/transcient response? dynamic compression? weak articulation? flabby/no-bounce bass? IMHO dynamics is not a strong focus for M.A. especially the heavy metal cones.
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It will be -you're measuring with DATS which runs a low [real world] voltage drive & extrapolates. MA measure SPL and T/S values under 2.83v drive conditions. My own test unit show almost exactly the same deviation measured under DATS relative to the exact same driver measured back at the factory, and again when I measured at a higher drive at this end also. This is quite normal; Yevgeniy over at Hificompass has discussed exactly the same variation with Seas when he was reviewing one of their new Excel units, & noted the shift between what he measured at a low voltage drive with DATS, and what was published. When he re-measured with the same higher voltage Seas used, his units came into line with the published.
This isn't to knock DATS -as I say, I've got it myself & use it all the time -it's a great little piece of kit which I regularly recommend, but I also have to keep in mind that Fs, Q will typically come out higher and Vas lower than is the case when measuring at higher drive levels, precisely because it takes a fairly literal approach to 'small signal' measurements. And strictly speaking it's correct, in that Fs, Qe, Qm, Qt, Rms, Cms & Vas were defined by Thiele & latterly Small as small-signal values & the reasoning is absolutely sound. But in many (probably most, these days) cases, especially with LF units, they aren't really operating under those conditions.
This isn't to knock DATS -as I say, I've got it myself & use it all the time -it's a great little piece of kit which I regularly recommend, but I also have to keep in mind that Fs, Q will typically come out higher and Vas lower than is the case when measuring at higher drive levels, precisely because it takes a fairly literal approach to 'small signal' measurements. And strictly speaking it's correct, in that Fs, Qe, Qm, Qt, Rms, Cms & Vas were defined by Thiele & latterly Small as small-signal values & the reasoning is absolutely sound. But in many (probably most, these days) cases, especially with LF units, they aren't really operating under those conditions.
Hi Scott.
Thanks for the info.
I don't want to have different values for TS parameters depending on the measurement device.
The frequency response is also quite different with and without smoothing, so I would like to have a unified standard.
I'm also curious as to which measuring instruments the simulators and calculators for audio are programmed based on.
Agreed -and I doubt anybody else does either. Unfortunately there's no industry standard for measurements and there isn't likely to ever be one either. All any of us can really do is try to ensure people know what protocols / equipment were used and how the results can vary based on that.
I let the MA200 run for about 250 hrs and changed them to a bigger box (about 98 liters) with 4 folds in a transmission line type enclosure. I used OSB (just for testing) with no internal damping material. They sound amazingly well, just a little bright with satisfying low frequencies and excellent mids.
Attachments
What does it sound like?
If you put a mechnics stethoscope on the baffle is it making ny noise?
dave
If you put a mechnics stethoscope on the baffle is it making ny noise?
dave