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MDAC First Listen (part 00101111)

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Yes, I originally had a single sub and I could defiantly locate the "Louder" position (the sub was located next to the Left speaker) - I've since added a second sub on the right-hand side which has helped rebalance the system.
 
JohnW said:
Yes, I originally had a single sub and I could defiantly locate the "Louder" position (the sub was located next to the Left speaker) - I've since added a second sub on the right-hand side which has helped rebalance the system.
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John, Geddes' approach is considerably more sophisticated and is based on the way frequencies below about 150hz behave in small rooms. His approach requires 3 or more subs.
 
Yes, I appreciate this :), while I was listening to the system with a single sub I kept thinking to myself - well what a load of "CxxP" that you cannot locate a single LF sound source.

That said, once the single Sub was placed between the speakers it sounded far more integrated.

I''ll try for 3rd sub when one becomes available.
 
fusion5 said:
Yes, my listening room :)

Nice room mode @ 60Hz
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Well once we start to play with the FDAC's DSP / Room correction I'm sure its going to be an eye opener... Even without room correction, its A nice feature to be able to measure your room / system - after playing briefly with subwoofers here in the Lab system I've given up on the idea of optimising the sub settings until I can measure what's going on, and as we will have the FDAC "Soon" I'll leave it until then :)
 
misterdog said:
Whilst we are on the subject the dual Calex supply is making a further improvement.

So, would there be anything to be gained from bypassing the internal supply completely, I note though that the internal power cable has 10 connections.
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Talk about a glutton for punishment; not content with re-capping 2 Calexes he now wants to pull the MDAC apart! All I can say is, Good Luck....
However, my reason for coming in on this is that I have another Calex improvement to report.
When I bought the MDAC I had a good headphone preamp, the Graham Slee Ultra-linear, though without the recommended LPS. I found it to be distinctly better than the headphone o/p of the MDAC, at least for driving my pair of AKG701s, and whenever I needed headphones since, I have been using the GS amp. I've recently added my own 24v LPS to it, and I leave it to you to work out what that might be. (clue- costs £20) It i indeed makes an improvement to the GS, and even better of I put an S-Booster filter in line.
Just out of curiosity I tried comparing this to the MDAC with the 3-rail supply, something I had not checked before.
John, my apologies for doubting- the MDAC heaphone o/p is brilliant!. Yes, the improved GS comes fairly close, but at least on small-scale stuff the MDAC gives some sort of sense of the space in which the recording was made, something very obvious on speakers, but i have not heard it on headphones before.
 
iansr said:
Errr, I think you need to read Earl Geddes' white papers on reproducing bass frequencies in " small rooms" by using multiple subs. His work builds on earlier research done by others in the past. Basically you need multiple bass sources as a starting point (note that phrase) for producing the best bass and that includes overlapping the multiple subs with the mains. You have to implement this properly though . . .
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If you are interested in multiple subsyou should also check out Welti's research, but that was not my point, often subs are not properly integrated, main speakers are not crossed over so continue to play over the subwoofer, ie both are playing the same frequencies.
Keith.
 
misterdog said:
These arrived yesterday £ 5.99 inc. delivery from China !
Highly recommended, the light is now fit for purpose (LED +push button switch) even removable to use as a separate light source.

$_57.JPG


11 levels of magnification, can be worn over spectacles.

No brainer.

I have no affiliation with Laozong Gou. :D

http://rover.ebay.com/rover/1/710-5...0001&campid=5338728743&icep_item=252254461326
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So I gave up my pride and ordered a pair that arrived today - very well made for GBP6!!!

I guess I have to accept I'm getting old... I just ordered a second pair as I dont want to share my pair with Jarek... :)
 
This site contains affiliate links for which pink fish media may be compensated.
JohnW said:
Yes, I appreciate this :), while I was listening to the system with a single sub I kept thinking to myself - well what a load of "CxxP" that you cannot locate a single LF sound source.

That said, once the single Sub was placed between the speakers it sounded far more integrated.

I''ll try for 3rd sub when one becomes available.
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+1 on the localization issue, John. I was using one sub to augment the bass on my M-L CLXs which only go to about 50Hz. While "tribal knowledge" is generally that bass is not localized below 60-80Hz, I subsequently read a study that suggests that it IS even down to approx 25Hz. Adding a second sub definitely solved both the localization issue but also gives the bass more soundstage since it is LEFT and RIGHT vs a summed signal feeding one sub.

I have since added a 3rd sub behind my listening position which is barely on but which provides a real immersive listening experience plus it seems to mitigate issues with room nodes...bass is deep and full without boominess.

BTW, I am using two Hsu VTF-15H MkII as stereo subs based on Dr Hsu's recommendation after providing listening preferences, room dimensions, furnishings, etc., and am extremely pleased with the result.
 
You could use REW's room simulation mode to model the behaviour of the room,with the subs in different locations, and use measurement to confirm.
Keith.
 
Most times when people complain about a sub sounding slow it's because they've not aligned the phase, so it is literally, slow, ie arriving at the listening spot later.
 
FWIW, I have a couple of the smaller RELs (meant for the TV audio market) one upstairs and one at another location. They are next to impossible to integrate properly in those two environments - when listening seriously I adjust them two or three times and usually finish up unplugging them. Maybe the right DSP kit would solve their tendency to boom - or perhaps the fact that they fire sideways as opposed to the Strata's firing downwards (towards a woodblock-on-concrete floor) is a factor. The key feature of the Strata in my main set-up is that it's unobtrusive: only if I switch it off does anyone ask 'What just happened to the music?"

Slightly off-topic, I can picture 20 or 30 (?) FDAC owners each buying a Umik and using it just once: would sharing one or two (in return for, say, a fiver and a refundable 50 quid deposit) make more sense, or would it be asking for trouble/tempting providence?
 
JohnW said:
Very Interesting!, any idea what the cause of the massive peak at LF?
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What room correction software/hardware do you have in your system to fix the issue?

my measurements are very similar to yours 40hz rise and big suckout in the lower midrange
 
stellablues said:
What room correction software/hardware do you have in your system to fix the issue?

my measurements are very similar to yours 40hz rise and big suckout in the lower midrange
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Is this with ESLs?

I ask because the lower mid-range suck-out would be typical ESL behaviour: the effect of dipole rear wave cancellation.
 
JohnW said:
To maximize our engineering resources we will design the Digital Input Card (DIC) so that it design is "triple purpose" it can be populated with or without the DAC / HDMI sections:-

1. HDMI Audio extraction & two Channel secondary DAC outputs

2. HDMI Audio extraction

3. Two channel secondary DAC outputs
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Balanced or unalanced output for the additional channels?
 
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