I like donuts! ha ha ha...Next trial: I stuffed the port with high density foam to try to limit the excursions in the 40 to 60 Hz region. This obviously helps with IM from heavy bass but also robs the mid and upper bass of "naturalness". Diana Krall's voice sounds too thin with the port stuffed so there you have it! If I had no other driver to choose from; I could be happy with the 7MS but getting the exact right enclosure is proving to be quite tricky; also, as I already said; if you need "loud"; you better consider 2 of these in parallel!??
I have no dietary restrictions but for those i set. Chocolate icing is nice. Are these in your reciepe book? --
They have never found any heart issues, despite using every test in the books including an inside out, upside down sonogram (they stuff the ultrasound bits into your lungs). Checked due to an unusally high level of an enzyme associated with heart attacks — my GP phoned in a panic asking if i was having a heart attack after seeing results of latest test for this (my pre-op tests).
More exotic baked goods are good too :^)
dave
They have never found any heart issues, despite using every test in the books including an inside out, upside down sonogram (they stuff the ultrasound bits into your lungs). Checked due to an unusally high level of an enzyme associated with heart attacks — my GP phoned in a panic asking if i was having a heart attack after seeing results of latest test for this (my pre-op tests).
More exotic baked goods are good too :^)
dave
Ok, how about a Boston Cream then? And you may get a cinnamon bun if there are extras. Just depends on the day.
Just don't tell your doctor where they came from.😉
jeff
I’ve probably never had a good boston cream. I had a cinimon bun at the hospital. It counts as excersize to go down to the lobby.
dave
dave
Congrats!!! I also don't have any real heart problems; they did every imaginable test on me as well; welcome to the club! At higher rates, my rhythm gets a little whacko but they said nothing to worry about right now.
More listening impressions: The 7MS sounds more like a wide-band midrange; the 7P sounds more like a true fullrange. I'm still getting used to the 7MS; without doing any real test tones I would say it would be good as a midrange from 400Hz to 4KHz no question. At times, it almost sounds too bright as compared to the 7P. Again, that nasty looking peak at about 12KHz is suspect. The reason I doped the 7P is that I couldn't make it sound right regardless of any low pass X/O 1st, 2nd, or 3rd order with or without a Zobel because it also has some high frequency issues. The doping tamed the harshness and HF ringing but didn't take anything away from the articulation or musical accuracy. I might try several different simple inductors next on the 7MS in an attempt to get a better overall tonal balance top to bottom. Of course; I don't want overkill here; just something a little more subtle. Sometimes the 7MS does sound more like a toy than a real audiophile driver (again; I suspect the non-linear modes in the top octave or so!???). stay tuned...
I just now placed an inductor inline with the 7MS. I chose 0.18 mH to start with; this is a Solen "Hepa-Litz" 12AWG equivalent so a premium quality part for sure. THIS HELPS!!! The top octave seems more well behaved and the overall sound balance from top to bottom is definitely better. It would be nice to have laboratory grade test equipment available to me again; I could really fine tune the complex impedance of any "crossover" parts combination against the impedance curve of the driver; especially the top octave where it rises rapidly. I generally prefer the simplest possible solution and try to avoid Zobels whenever possible. I have other inductors in my parts boxes in the basement but I'll keep the 0.18 mH on there for now.
I replaced the series 0.18 mH inductor with 0.22 mH. This seems to be too much so I am now "bypassing" the 0.22 mH with a 23 Ohm resistor. This seems about right for now. I am using very familiar recordings and using temporary clip leads to quickly go from straight (no inductor) to inductor inline to inductor inline with parallel resistor. In doing this several times; the best combination is 0.22 mH in parallel with 23 Ohms. This seems to give me the upper mids and highs that most resemble my 7P. Perhaps a 0.20 mH inductor by itself would give approximately the same results but I don't have any in my parts boxes. This is where the experimenting comes in; if one were to look purely at the impedance curve at the top 2 octaves you might falsely conclude these small inductor values wouldn't make any difference. Well, they do, in fact, make a difference, it is subtle but that is exactly what I'm after here; I call it fine tuning. More later...
I have determined that a standard BR (vented) box tuned in the 40's is just not going to work too well; the IM distortion from lower bass notes happens even at moderately low power levels. The arrestor doesn't even "kick in" yet but the cone travel is just too great. A more sophisticated design like the FH, Pensil, etc. would probably a much better match. I now have the second 7MS in a smaller, closed box. This is about 5.4 L; calculated parameters are: Qtc 0.79, Fc 104 Hz, F3 94 Hz, Amax 0.18 dB@ Fmax 233 Hz. So far, so good. I have the same 0.22 mH and 23 Ohm resistor in series as just before. The bass is tight here without being boomy (+0.18 dB @ 233 Hz is not detectable at all as one would easily guess) so a Qtc of just under 0.8 seems to work quite well here. I can't really tell yet about any mids or highs that may be too relaxed or pronounced as the break-in is just now beginning. At very first listen; I think this smaller closed box is actually a better match than the larger closed box...more time needed obviously...Cheers!
I don't want to get too involved here, but FWIW, assuming the published data sheet spec. and about 0.1ohm series R for connections, speaker wire &c., then 15.5 litres with an Fb of 45Hz isn't an alignment I'd choose in a hurry. It's a quasi-EBS style -with regular lagging of the walls it's likely to have minor peaking at Fb and also a rather narrow / sharp box tuning, both of which tend to promote an excessively boomy / 'one-note' LF characteristic, especially near boundaries. Deflection is likely to be about 1.5mm / 1w through the midbass, give or take. Significantly higher Vb than I'd use -about 50% more & with an Fb about 18% lower than the vented box I did last year. As ever though, YMMV.
No; actually, involvement, experience, opinions, ideas (good and bad) are what I seek and all are welcome. My next thought was that I will try a smaller vented box. The 0.56 cu ft box was something I already had and it was very close to the Hoge based calculator in size and tuning. My 0.23 cu ft box "might" work vented; I was going to run those calculations later. GF is on her way over; we are going to dinner and then Home Depot so I can some PVC pipe for vent tubes. I'll be able to test different tunings quickly and easily with various length pipe on hand. Like I said, I'm retired so experimenting is actually something I rather enjoy. Besides; who knows how accurate the 7MS TS parameters are? Sometimes, initial specs. change quite a bit from prototypes to production runs. That's why I asked in the beginning about independent, 3rd party testing. I like confirmation or real world updates on OEM specs regardless of brand or price range. Even in my newest, smaller (closed) box; the 7MS can't take much power or bass compared to my 7P's. They really are not going to get very loud unless they are high pass filtered at 80 Hz, maybe higher. Putting 2 of these in parallel may be something people might consider also. The 86 dB sensitivity spec. could even be off; they may only be 84 or 85 dB ??? Thanks, we'll keep experimenting and reporting on this end. Would love to hear back from other 7P and 7MS owners BOTH.
Got donuts for you. No Boston Creams thou. Let me know when you're home, and I'll come up.
jeff
I’m not a fn of donuts with ous in them :^)
Today, tomorrow, the next day, probably out TUes or Wed.
dave
Today, tomorrow, the next day, probably out TUes or Wed.
dave
Not fond of donuts with mousse in them? Ok, these have Earl Grey pasty cream in them, so I guess that's a no then?
jeff
Scottmoose, I'm trying a smaller vented box now. About 10 L so calculated Fb is 60 Hz, F3 53 Hz. I much prefer the 15.5 L box; better bass overall (low, mid and high bass ALL sounded good and well balanced). The smaller box just sounds too "thin" or "weak" for my tastes. The neighbors are sleeping in Sunday AM. As soon as they are up and about; I'll turn it up; maybe the Fletcher Munson curve is proving itself at these lower listening levels!? I didn't notice the "one note bass", any "boominess" or "sloppyness" in the larger vented box so maybe I had the stuffing about right. Plus, the published TS parameters may not be that accurate so, again; it would be really nice to see some 3rd party tests and measurements after these 7MS gain some popularity in the US and Canada. Next experiment I may try two 7MS in parallel in my 0.56 cu ft box but closed. I ran the numbers on my smaller (0.23 cu ft) box; too small for BR; there would have been at least a 3 dB bump around 100 Hz or so (at least according to the online calculators I tried). More later...
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