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BioBrian

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About BioBrian

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  • Birthday 06/11/1954

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  • Location
    Mountain River
  • Country
    Australia
  • First Name
    Brian

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  1. Hey, thanks! We might all 3 be well-aged by the time it happens, but here's hoping. And while I've still got my silly pants on, I thought it was really cute that Accuphase custom-built a couple of drink coasters on top of your new preamp 🙂
  2. It's amazing how a quality source can show through downstream compromises. I really can get a sense of the space and detail that this incredible system has, just through your iphone, and these little things on my desk. It's quite fashionable to say "it's useless spending money on a good DAC, or cable, or whatever, if your room or speakers are not perfect", but I think a lot of us know that we DO know when something special is upstream. Certainly the case for me, here. Now I almost feel I don't need to make the trip! Unless you have a Bin 389 on the go, of course. It's been a few decades since my last one, but it was close to the source of my red education...
  3. Wow thanks Chanh, you just turned my little Logitech computer speakers into Magicos! Awesome spaciousness, timbre and claret-y!
  4. They should have said HT bypass doesn't stand for High Temperature? Hope it's OK. Lovely amplifier.
  5. Great stuff. I like it when Anthony says his amps have almost no wiring. I'd rather see solder than spades or crimps, but I guess nothing is forever, and transformer wiring always seems to have spades. Crimping is a game of guesswork, for me. "crimped and soldered" Love it, but on the forum? Out with the umbrellas 🙃.
  6. OK, yes, the pilot hole size is critical - I'm lucky to have inherited a set of fractional drills, but not very good at decisions... I know there are tables somewhere... I actually use (when possible) the vertical drill to start the tapping - just lower it with one hand and turn by hand with the other - if I'm lucky the pressure can be increased at the right rate, and when it gets too hard to turn, the chuck can be undone and raised, and the rest done with the tapping tool. But it looks like your tool has some clampy thing on top, hence my question. I wish there was some screwdriver-like tool, with a bit of length, to make alignment easier.
  7. I saw the photo, but how did you tap those holes so square? (My tap has those ridiculous side-handles that guarantee you can't keep it straight). Looks like you got the case (back panel) anodized after drilling your holes? I'm very impressed with your attention to detail - everything just looks right, even down to the wire feeding.
  8. Thanks Steffen, that clarifies some things well for me.
  9. Thanks Matt, it's still an option, and surely a very enjoyable one. I'm easily seduced though, and have a couple of problems with this approach, so don't want to substitute one compromise with another and get all complacent. The biggest problem is that the acoustic outcome won't match what the mDSP does, especially with passive XOs. I find the drivers can be quite perverse in their refusal to follow instruction, to the point where I can't really trust the in-room outcome from even line-level filters, such as Xkitz and Elliot. I wish it could be easier, but can't see a way out of experiment; I think we are moving closer to having the subs thing work better. (4-ways still need work).
  10. Thanks for your persistence with me, Dave. It's sinking in - I'd forgotten this aspect of LP filters. During the night I revisited WinISD, and checked out my 2 sub versions, with their specific boxes and vents etc. I hadn't taken in the importance of phase here. I tried various filter sims, and got the most difference with eg 2nd Order vs 4th Order, so went to all 2nd order, which changes phase less drastically. The differences weren't as bad as your graph above, but I could only get the lines overlapping at XO by having them both at 100 Hz. Here, the lines converged at that point, slowly separating a little going down towards 20 Hz. Having the 'main' on 100 Hz and the sub on 80 Hz (with these drivers/boxes) produced parallel lines all through the frequency range, and only a few degrees apart - that seemed OK. But whatever signal the drivers are fed, the acoustic response is not going to match the sims (with passive at least), so I'll need trial and error. It's clearer what I need to measure now. First I have the more 3rd World problem of how to encourage some of all this water to come out of my taps.
  11. Ow, my brain hurts. I've seen this over and over, but still await the gong moment. Altering the phase by moving the speakers (many metres) might help the phase 50-100 Hz, but would damage 20 Hz, which is working well in this scenario? So I won't pursue that. But it looks like if I move the blue sub knee closer to the red 'main' one, the phase will be more equal, notably towards lower frequencies, where they'll sum better than higher, which would help. On the other hand, I could move the 'main' knee lower, so they sum AND output relatively more toward the lower frequencies? What would that do to integration with the 8" though, I wonder? If I give all woofers equal LP filters, it could work against me, in having too much summing around 50-100 Hz, handing all control over to the room?
  12. That's what it would have been doing, driving the whole district. The large rocks have a habit of "here today, gone tomorrow". Must go and see if my "whale rock" has moved. Had to check the 3 Huon Pines just now, that I planted on the river's edge about 40 years ago. All safe and well. In about 900 years I'll be able to do a "sustainable selective logging" and make some nice little subs, appropriate to the population and housing conditions.
  13. All good, thanks. I'm digesting it all slowly, but some of it's a bit hard for my old teeth. I went up to start measuring, but the roar of the river is still echoing around 'them thar hills' too much. Can't get past this one for now: IF I set the main LP filter at 100 Hz, 24 dB/oct, and the subs one at 60 Hz, 24 dB/oct, does it necessarily going to be "out of phase"? Say at 80 Hz, one would be simply outputting more volume than the other - could they not still be in phase, just different contribution levels to the whole?
  14. At 60-70 Hz, if it's not the room, I suspect it's more to do with the interaction of the 8" and 15" drivers in the mains. I've had trouble getting meaningful measurements of this, and I'd not be surprised if measuring these from 3.2 m distance (as in listening position) shows up peaks/cancellations (including floor and ceiling bounce) there. It all gets crazy complicated! Warning to prospective sub builders: "don't try this at home". Well unless you do it the proper way, haha. Lots to try. So with the Xkitz, @davewantsmoore, if I need to match slopes I need 2 lots of 24 dB/oct filters, and (groan) another stereo amp? Should save my money?
  15. [Edit: you beat me again - I just clicked as your 2nd post came through, so I hadn't read it.] Maybe it's just luck then, that the four 15" drivers aren't summing at 50 Hz, but filling in the bits I wanted. I have to agree with the cancellation thing though - it's quite frustrating to walk around and have to feel the gestie drivers with a long rod, to even be sure they're earning their money. What's happening around 60-70 Hz does need a look - ATM I think it's more the room, but I can try more mike positions. I think at my level of understanding, it would be good to trot out some individual frequency tones and check out what's happening. I have noticed that when playing organ music, there were notes missing in low scales before, and now it sounds like they are all there. I'd really like to get a recording of a slow chromatic scale, or notes from 20, to say 150 Hz. Sine wave tones are so out of tune!
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