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In Reply to: RE: From Hell (via a pair of old MMGs + add-on 10" woofers) posted by andyr on May 15, 2015 at 01:42:59
Hey, Andy! I was thinking about you last weekend, as I listened to the Notre-Dame organ. The Frankies' size would have delivered quite a spectacle in my room.
If you can, plan for positionings that allow you to align the woofer drivers next to each Frankenpan. I can't, for lack of space on the sides of my Maggies. Luckily, the woofers are so shallow (6") that they can be placed right in front of each [already raised] MMG. (Of course, I am having a hard time making it all look "pretty" :-))
The resulting time alignment is close enough to deliver incredible integration. This includes delightful instrumental textures that many folks would lose if their Maggies got subwoofers slapped on them.
Follow Ups:
Yes, very important JBen - and not paying close enough attention to time alignment is, I suggest, the main reason why many people have such average results, adding subs to Maggies.
Luckily for me, the guy who is building my subs is right on top of all that. :-)) He explained that when you add subs to "main speakers", you need to apply a time delay to the main speakers - so they come into alignment with the signal coming out of the subs. Sure you can physically move the mains back behind the subs the right distance, to get the appropriate X milliseconds delay ... or you use DSP. And DSP gives you room correction as well! :-))
But if you delay the bass panels to line up with the subs ... you also have to delay the other drivers. The DSP unit which provides the delay can also provide the HP & LP filters - so I will be replacing my current 3-way analogue XOs with a 4-way DSP unit. A whole new world! :-))
Regards,
Andy
Andy, you put the finger on what was frustrating me during tests, for years. The simplest manner in which I can say it is this: I have to stay in analog after the initial Digital-to-Analog conversion. Furthermore, if I ever add a turntable again, I'd never want the signal to undergo conversion to digital, at all.
No manner of DSP could help me because it needs to reconvert to digital. I tried many DSP computer-based programs and most types of High Rez algorithms. They solved timings...even facilitated changing slopes & xover points. However, they always spoiled other things dearer to me.
After many experiments, the stark reality hit me. Unless I found a key to analog "time travel", it was better to align the drivers physically as best I could. The surprise was NOT that this worked as far as timings, which was a given. The surprise was that I did not have to filter the Maggies feeds at all...they are running full-range, which I was hoping for but would have bet against (mainly due to some peculiarities here).
The net result is tonal & textural seamlessness to a degree that I never expected. I am now trying to figure out more fully what is helping the most. Of course, had driver timings not been aligned well enough, I'd be drowning.
I would say you could have a problem with your current placement, JBen?
The - what, 18dB ... 24dB? - LP filter on the subs causes a timing difference. If you are running your Maggies full range it will be less (the way I understand it) than if you have a matching HP filter on them ... but the subs need to be in front of the main speakers, if you want to use physical time alignment to delay the mains, rather than DSP.
In my situation, the subs have to be in the front corners of the room - so I already have a physical time delay, compared to where the panels will be, as well as the filter-induced delay. So DSP is the only choice.
Regards,
Andy
Andy, I expected much more trouble getting time integration. Subconsciously, however, I did some things right (that's me not admitting to the reality..."dumb luck" : - )) .
Oh well, one design "accident" was that I made the boxes 6" deep. I coulo explain, but the long story short is that it was for other reasons. Yet, this wound up allowing me to place each woofer right in front of each MMG. (Less than one inch separates them.)
At the frequencies involved, this is good enough to "help the cause". It does allow, for example, for some gorgeous textures on bowed bass strings to be better heard. They become stronger but do not lose their rosin-impregnated texture vibes in the process. LOL, you may take these things for granted on the Frankies right now. Me, I need to strenghen their volume without their losing their personality...hard work it is.
One other thing may have helped much. Yes, it is 24db/octave, though I also got commendable results with 12db using a pair of cheapo filter boards ( <$18US) from China. The specs for he 24db low filter system I ended up with (UK-design, Chinese made) read like a dream solution for me. It is still under test for a couple more days and I am asking the supplier a few things. I'll look up the link when I get home and send it to you and Satie. (I am staying with friends tonight.)
Tell us how it goes on the SQ of the DSP units you try out.
I have not yet heard a DEQX, TACT or other high end DSP with good DACs so don't know how to weigh the positive effects of room processing and time alignment against the effects of the digital AD DA loop. My limited experience has not yet shown a net positive relative to PLLXO and physical time alignment.
Yes, I was worried too, Satie. Until a mate of mine who has Wilsons and a very high-class vinyl setup tried out the top DEQX rig (the one with an analogue PSU, not a SMPSU) and said that he didn't notice any sonic degradation.
So we'll see if this is so! ;-))
Andy
Satie, it seems like you and I went along parallel trails at times. Once the PLLXO does its good deeds, it is hard to let go of the blessings by allowing DSP in. I've been there and refused to let go of the analog/PLLXO blessings. Which is why the woofers took so long.
Of course, if a room is too challenging to tackle fully in the analog domain, the priorities could be different. Then, DSP could be easily indicated.
Since you have a less common setup, I'll keep this in mind when I write the stuff about the woofers here. Actually, hmmm, don't be surprised if I email you a different version (to spare the others from a longer set of explanations).
I would be happy to see what you were thinking in more detail.
I see that we share many of the same considerations. I can say that my own AD/DA looping on a tascam 800 and the musical fidelity end up sounding so much more like the DAC then what was fed into it (though very good on the MF and good on the Tascam) that there is no way I am convinced this would work for me.
Playing back streaming at 320k was a real let down, but live professional HD uTube recordings do ok and remarkably better than I expected. Converting the 320k PCM into DSD did it a favor in de-edging the sound. But it was not good enough.
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