New Markaudio MA200 8" Driver

Jump to Latest
#122
with a more typical arrangment and on published specs (i never had this driver in my hand, nor measured) i got a 65L ported with a slot port of 10x5 and 13cm deep for a tuning to 35Hz. That is a standmount size speaker, not a bookshelf. But it looks promising, i just also want to see off axis responses measured by someone. This is a fast calculation, not a finished design...
 
  • Like
Reactions: tubelectron
#123
True on the phase.
A room really lessens the audibility.

On the 10f/rs225 thread, one had slid the 10f back for alignment.
1725578472402.png


"To my ears this offset is very important, you miss quite a lot, when you do not mind....and I really do not want to go back to any other speaker any more, which is not transient perfect...."

He said it was easily heard outdoors, inside less.
"Still I have to say, that outdoors it sounds way better with the offset, compared to no offset and the listening height = woofer axis. I assume that holds true for indoors too. I go with the offset. It sounds way more transparent and true 3D like."



And of coarse, very transient material like a wood block, is easier audible on a time aligned.

Otherwise, I assume it is heard as maybe different sounding.

I remember where a member commented his wife (non english speaking) had an easier time understanding voice on either a 6db time/phase or a full range driver (I can't remember which).
 
  • Like
Reactions: wchang
#124
I'm not so sure about 'of course' given how much evidence from properly controlled testing there is that it's not audible except in extreme conditions. Same for the 'I assume it holds true' bit cited, especially with the 'it sounds way more transparent and true 3D like' which doesn't mean much to this cynical soul here. 😉 So long as he enjoys though, so much the better -that's the point. 🙂

What does seem at least suggestive to the miserable old s@d at this end 😉 eyeballing the picture above though, is the potentially chronic diffraction off those hard edges of the main box below the mid-tweet. A lot of the time-aligned speakers, when it was a fad back in Japan in the '70s, had a load of damping material across that flat surface -although typically they tended to be with tweeters crossed rather higher so the shorter wavelengths were more easily damped out. YMMV as always of course! in principle it seems a nice idea if you can, notwithstanding it only works at one point in space, athough the tradeoffs always seem to me to be more trouble than they're worth. It might mean you get to play with absolute polarity, which isn't really viable with other systems, although the audibility of that is also extremely small & relies on the handful of recordings that are made where it hasn't been mashed up (78s are probably a good source, in terms of how they were engineered).
 
#130
Re: offset
With LXnano as desktop speakers, person seated and head somewhat tilted lower, the drivers are acoustic-center aligned (notice relative position/tilt) with respect to head/ear and image is projected well behind them. If head tilt is different the depth effect is reduced. Supertweeter on top (like the pictured new Mark Audio), optimal offset can usually be determined by ear with little effort and precisely repeated within 1mm.
 
Last edited:
#131
norman bates said:
true.

In the above picture, i would cover the "shelf" and the tweeter box's face with f10 felt.

https://www.speakerdesign.net/audioXpress/diffraction/diffraction.html
Click to expand...
That would help; the old Technics speakers were quite sound in that respect, for the filter frequencies used. IIRC though, X's design is running 1st order at about 900Hz, so the mid-tweet is motoring down a fair way, and it's a very deep shelf pictured (that's why X leaned toward the simpler approach of using the midbass as the listening axis & positioning the mid-tweet lower on the flat baffle, although that can come with its own issues with reduced HF at the listening position itself) so I'd expect it to be a bit more 'challenging' than is usually the case. Troels did some interesting work on diffraction for his stepped-baffle LR2 jobs -not sure if it's still on-line without going through the wayback machine, as he's pulled a fair bit of his older material, but it's probably lurking in his Jensen speakers section.
 
#132
norman bates said:
I think people also wire the drivers out of phase, move the acoustic centers for the deepest null, then reverse the phase on the tweet.
Click to expand...
You can, but that only 'works' with phase-complimentary types e.g. Linkwitz. With Butterworth, where the drivers are aligned 90 or 270 degrees apart, you have no reverse null at the crossover and (theoretically) flat frequency response whichever polarity they're wired in & a flat power-response. Doesn't always work out so pat of course. 😉 For something like a Linkwitz or the variations, a polarity flip can give you a good quick idea of the phase alignment across the transition band, although it's usually as / more revealing to eyeball & line up the individual driver phases over the widest possible overlapping BW (or more).
 
#133
wchang said:
With LXnano as desktop speakers, person seated and head somewhat tilted lower, the drivers are acoustic-center aligned (notice relative position/tilt) with respect to head/ear and image is projected well behind them. If head tilt is different the depth effect is reduced. Supertweeter on top (like the pictured new Mark Audio), optimal offset can usually be determined by ear with little effort and precisely repeated within 1mm.
Click to expand...
Yeah, I'm not surprised; this can be the downside -the acoustic centre alignment when the drivers are physically offset relative to the reference plane only really works on one axis (often one point in space) so you can get relatively extreme situations where even moving your head will make audible differences. Focused arrays have some similar characteristics in that sense.

It can, although that's usually due to the overall system behaviour and its effects in the frequency domain at the listening / measuring position if the drivers aren't properly aligned.
 
  • Like
Reactions: wchang
#134
Bfpca said:
Since the F4 has no voltage gain you will never achieve 25w at 8 ohms using the 45 amp as a preamp. The output will be limited by the voltage the 45 can produce which is going to be 4vrms at 2w into 8 ohms. If you have a 16 ohm tap you could use that and gain some output voltage to feed the F4. You will gain current output from the F4 and if you have 4v into 4 ohms it gives you 4 watts. With a 16 ohm tap 2 w = 5.65v which would give you 4 watts out at 8 ohms or 8 watts at 4 ohms. So if you want to keep the 45 in the signal path you will need a gain stage of 4 or more to give you enough output from the 45 8 ohm tap to drive the F4 to 25w at 8 ohms which is 14vrms. You could use the 45 to drive a preamp, then into the F4. In all cases the 45 output needs to be loaded by a resistor across the output terminals. It’s an interesting experiment and it might be useful to speak to someone who has actually done it, or finding someone with an F4 who would be willing to set it up with your speakers to try.
Click to expand...
Showing my ignorance here but please can you explain why the resistor across the outputs is required? Is it simply that the F4 does not present any load to the 45?
 
#138
  • Like
Reactions: LeifB60, Ivo, waxx and 1 other person
You must log in or register to reply here.
Top Bottom