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In Reply to: RE: The unplanned "extended lows" sudden project posted by JBen on January 24, 2015 at 12:54:15
So, Bass Master Flash is back in the lab...HHHHmmmmmm....couple of questions...from my small cement-head brain...
Signal, into a crossover of some kind or not?
I see the speaker is a 4 ohm load...
Power, what are your amp plans for this project?
How low do your MMG's actually go in your room?
My 3.7's hover between 34-37 kHz...all stock with fuses...
Since I have sold my subs, (they never really blended well with the 3.7's), 80% bad to 20% good, all material dependent...I really have not missed them at all, yea a little for movies, but my neighbors are happier since they left...
Thanks
Mark
Follow Ups:
Small cement-head brain? Yeah, right, LOL! I'll update, and try to cover your questions. To some of your questions (other answers implied further down):
- Bass signal today was filtered by a section of my Denon receiver (bass management of a digital signal sent from the USB DAC). This Denon AVR allows me to feed the mono "sub-woofer out" signal back into itself, to two of it spare power amplifiers. The Denon, in effect, can send over 200W RMS into each of the two 3.5 ohm voice coils in the woofer. So, the receiver handled low filter, timing, volume matching and power... WITHOUT intruding on the analog stereo signal that feeds the MMGs. (This, because the same USB DAC sends a simultaneous analog signal to the passive pre > > PLLXO bi-amp > > 2x power amps > > tweeters & mid-bass drivers. The MMGs are driven full frequency.)
- Later, I plan to have two woofers. Each may have a separate active low filter set (as 2 stereo channels). I may need to build something myself but I also sent for some Chinese cheapo circuits via eBay. If these work well enough, then I can share this with others. It would be easier and inexpensive. In my case, these would go in the same box as my hybrid passive preamp. Each would feed off the same analog signal sent by the USB DAC.
- The signal will then go to a stereo power amp. I could use the same power amps that I am using in the Denon AVR. However, it is more likely that I'll use an old NAD 2200PE (freaking powerful mule despite its age and power rating) while I find something better.
Anyway, the "lab" (living room) was a royal mess this evening. I received the first woofer today and decided to rush and mount it in one box. Boxes, tools, cushions, tray tables, a chair and things were strewn around in my mad dash to assemble the darn box and make it sound. So, the room was not typically arranged...but after two hours listening -- doing initial tuning by ear -- I sat down for enjoyment. It seems to be darn close to the mark for a "round 1".
I heard the best quality in "low bass" that I've had in this room. I did not lose any of the good stuff from the MMGs. The new woofer simply added clean bottom extension and tied up well with the panels' textures & timings. It was a bit surprising given how many a pricey subwoofer that I've tried here. They simply failed or required much tweaking to get even close. In fact, I am a bit frustrated...too easy...hoping that I heard wrong. I am sure that in a couple of days I'll hear the real horrendous weaknesses.
That said, I tried a minor reality check. I ran a quick set of frequency sweeps with pink noise (shown at bottom). They seem to agree with what I heard. Yet, I'll take better measurements (sweeps with timings, phase, impulse, etc) later. These should show that the fun is not over, not by a very long stretch.
Mark, like you, I would rather have no extra bass if it is "bad bass" that subtracts from what the planar drivers do so well. Given that I am no genius, despite my encouraging start right now, I simply KNOW that I am going to crash and burn with this project a few times.
(In the chart below, 1/6 octave smoothed, the lower trace [orange] is from a few weeks ago. For clarity, it is shown here at a -20db offset from the other 2 traces. Also, the bass peak displayed in the 50-60hz region does not sound as strong to the ears, nor is it "peaky" in character.)
Edits: 01/28/15 01/28/15
May I ask what Demon you are using, I have a avr-4800 laying around and wanted to know if it is good enough to try on my mmg's.
Nicolas
Nicolas, I suspect that you can squeeze some serious sound out of that oldish but sturdy 4800. I am away from home right now and can't provide details but here's what comes to mind.
Key, from what I remember, is that the 4800 has one whale of a solid power supply. My own Denon AVR 4306 was chosen because of similar power supply strengths.
Sure, the 4800's digital stuff is nothing to brag about. However, it can be used in "direct" mode for rather impressive analog stereo, more so via EXT-IN inputs. MMG's can punch you with it, and sound sweet also. This is largely using it as an integrated stereo amp rather than as surround or digital processor.
At the time I toyed with one, I had not yet developed some tricks that enabled other Denon AVRs (of later times) to go way beyond the ordinary. I think I did buy the 4800schematics because of how impressed I was. I'll have to try to find them when I get home. Meanwhile, you may want to give it a dusting and drive your Maggies hard with it for a re-break in.
I like that the unit has a sub out, and i can run the speakers direct,
it is so heavy i do not trust it on my tower shelf as it has glass shelves.
I'm using an emotiva xpa-200 which has the umff to drive the maggies with a
adcom gtp-400 as a pre-amp. If the denon sounds good i may wait six months
to read up on the .7 reviews then upgrade and sell the emotiva and adcom to
cover the difference. Here are the power specs for the denon.
Amplifier section: Rated output power (20Hz–20kHz, <0.05% THD): 125Wpc x2 channels into 8 ohms (21dBW); 150W maximum continuous into 6 ohms (22dBW); !z0.8% THD, 20Hz–20kHz. All 5 channels run simultaneously: 125Wpc into 8 ohms, <0.7% THD at 1kHz only. Frequency response: not rated. THD+noise: 0.008%, 8 ohms, 20Hz–20kHz. Intermodulation distortion: 0.002%, 60Hz+7kHz mixed 4 to 1, 8 ohms. Noise: –110dB (IHF, A-weighted). Input impedance: 47k ohms (single-ended). Input sensitivity for unbalanced input: 1.1V. Output impedance: 0.1 ohm (1kHz). Power consumption: 10.9A.
Nicolas
Nicolas, that 10.9 amp current rating kind of explains what I heard.
Then, though this tablet is slower than tar to search the web, I just found the review linked below. It brought a smile to my face. You may like it, too.
Hey Jben
Thank you for the in-depth description, always interesting and informative...I was wondering on how and what type of signal you were going to get to an amp...then the amp it self...
I look forward to hearing how things are going as you progress with this project...early signs look very promising...
IHMO, that is a very impressive plot. Your MMG's go as low, if not lower than my 3.7's...
I have really gotten spoiled by that Maggie bass...My Monitor Audio FB 210's worked great with the 1.6's, but really just did not cut it with the 3.7's...Yes, you are correct MORE bass is not necessarily mean better bass...we have all been exposed to systems that have some monster subs and the owners or dealers are smiling as things are shaking...no hint of musicality, but you can "feel" it...
The picture is the Calix Phoenix, I heard these at CES 2002, ($85K back then). These produced bass the likes I had not heard before...they were playing this very delicate traditional Japanese music, this gong came in and a very large animal skin drum...that drum resonated through my whole body...the guys I was with we all looked at each other smiled and went whoa...you could hear that mallet they hit the drum with, was also covered in some type of skin...there was skin on skin thwack that was palatable...very cool...
As I have said in the past, with condo living, I am not looking to add subs in the near future...I am currently looking at Music servers and DACS...I want my CD collection controllable via Ipad...I move pretty slow in this hobby...I am going to try and get to Chicago for the Axpona Show in April...
As always Jben...great stuff...
thanks
Mark
Mark, before I forget, yes these MMGs go lower than usual. However, it is caused by a mix of things, many of them sheer luck...some are skill, of the opportunistic kind, like Teflon caps on the PLLXO...Russian vodka-smelling but cheap : - ))Now, I've heard the 3.7 driven by a Magtech go down to textured lows that are deeper and sweeter still. They retain definition better. Paired to the ribbon tweeter capabilities, the darn things are easily the best stock Maggies out there. (I have not heard the 20.7 yet but, on several occasions, the 20.1 never made me love them).
Anyway, the extended-bass project is going slow, but it is going. Surprisingly, it has stayed promising even after some heavy break-in pounding on the driver. On Friday, I dusted the old NAD 2200PE power amp, which I had kept in reserve for possible "woofer duty" for years. I could have kept the Denon AVR powering up the woofer but it is too enclosed -- heat builds up. So, the Denon AVR now only does the filters for the lows and sends this to the NAD power amp, which is well ventilated. It has one channel in need of TLC but the other channel is enough at this time, since I am in "subwoofer mono" for now.
The NAD's channel nominal 100 watts kick the woofer like a mule...even into action movies, which I had not expected the woofer to handle so well. [The NAD amp almost blew the Velodyne subwoofer's driver to pieces years ago when I used it while Velodyne fixed its plate amplifier.]
The rest of the parts, including the ones for an additional woofer, will take time to arrive. For now, I'll be exploring that single woofer's behavior in a few modes.
Oh, yes! Nice sight, those odd speakers are; would have loved to hear them!
Edits: 02/04/15 02/06/15
I am thinking that you have room to raise the subwoofer volume by 6db or a bit more and lower the XO fteq. You would want that in order to have the MMG resonance peak be less prominent by raising the "background".
Satie, I believe that you are right in that I have 6db+. In fact, while tuning by ear, I had a +10db "electrical signal output" above the acoustic levels shown (without undue issues). Then, I back-tracked to "total audible disappearance" except for the extended bass I wanted. (and I was very surprised that this was so easily achieved...but see below...it may not last)This evening I won't be able to do much (working late). Fine tuning and breaking-in are in order. I do plan to add more polyfil to see if I can lower f3 slightly more. As it is, I made a mistake and ordered the boxes with .51c/ft internal volume instead of .62 , which I had intended. (Both volumes are in the "acceptable range" according to the manufacturer but .62 is better for flatter/lower bass output.) The addition of the stuffing is a trial & error process. One other thing is that my wife is punishing the woofer with movies today and tomorrow. These woofers DO change with use. I just spoke with her and she believes the deep bass in "Transformers" has now transformed the woofer. Late tonight I may watch more bass-heavy movies to further the advance break-in changes.
I need to make these behaviors stable before making final adjustments. After this happens, I wonder if what I heard last night will ever return, LOL!
Edits: 01/28/15 02/06/15
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