Hi mars1234,
What are the values of Zmin (minimum impedance) at +/- 35Hz and around +/-72Hz?
Regards,
Djim
What are the values of Zmin (minimum impedance) at +/- 35Hz and around +/-72Hz?
Regards,
Djim
nice to see the drumrizer preforms that well,being such a simple design.
and its not that heavy ,being a fridge size, with the 1/2" pannels 🙂
to bad the keystone had the "wrong"driver.
kudo's
and its not that heavy ,being a fridge size, with the 1/2" pannels 🙂
to bad the keystone had the "wrong"driver.
kudo's
Hi mars1234,
Thanks Martin for remeasuring your Keystone. Interesting to see that there is more than one Ohm difference between Re and Zmin.
Regards,
Djim
Thanks Martin for remeasuring your Keystone. Interesting to see that there is more than one Ohm difference between Re and Zmin.
Regards,
Djim
Mars1234, what is the purpose of the red arrows you put in the image?
I repeated the impedance measurement inside (previous one was outside, I thought maybe city noises and wind gusts could have caused ripples; also started the measurement at 5 Hz instead of 20 Hz):
I'm going to see if I can switch the 18TBX46-4 for the 18TBW100-8 I have...
I repeated the impedance measurement inside (previous one was outside, I thought maybe city noises and wind gusts could have caused ripples; also started the measurement at 5 Hz instead of 20 Hz):
I'm going to see if I can switch the 18TBX46-4 for the 18TBW100-8 I have...
Attachments
Some of us care about distortion and other outcomes. SPL doesn't mean what is seems to show when there's lots of harmonic distortion present. And even more, the perceived sound level (etc) is something different too.
All of those traces showing SPL are also harbouring THD data and just needs the press of a button for anybody to post 'em.
B.
All of those traces showing SPL are also harbouring THD data and just needs the press of a button for anybody to post 'em.
B.
Mars1234, what is the purpose of the red arrows you put in the image?
I repeated the impedance measurement inside (previous one was outside, I thought maybe city noises and wind gusts could have caused ripples; also started the measurement at 5 Hz instead of 20 Hz):
I'm going to see if I can switch the 18TBX46-4 for the 18TBW100-8 I have...
Hi Thijs666,
It seems more pronounced in your measurements? - but we're not comparing apple to oranges here - try the 18sound driver or a 18SW115 if you can. Please note that my build was very early on and Art's dimensions were off for the Keystone. See attached dimensions prior to my build. It still sounds awesome - cheers Art
Attachments
I provided a link to the REW measurement file for anyone to download:
https://drive.google.com/file/d/0B85db-5ynA7wYUI4QVFWd3REamc/view?usp=sharing
There are many settings possible for showing THD, so I refrained from posting screen dumps... but I'm willing to if anyone tells me the 'standard' settings in REW.
Ah, ok.
Hmm, the 18SW115 costs about €420 ex shipping here in Europe (about $500). I wish I had that kind of money laying around for just trying 😀.
Wonderful. Great to have your data available to all. Thanks much.
Below I've presented the THD data for all the subs in a form that is new to REW called "normalized". Think of it this way, if you EQ'd everything to absolutely the same flat response, here is what the distortion would be.
Frankly, I am impressed by the low distortion and without any obvious little peaks of grief.
Below 50 Hz, some speakers are running 1-2% distortion but that's not too audible.
Below 40 Hz, the distortion rises, even hits 50% at 20 Hz with one speaker. The distortion probably seems to other people like it would sound awful. But I doubt that. What I would point out is that when you are playing a 35 Hz note from a synthesizer, the distortion harmonic is louder to your hearing than the fundamental. Again, with music (esp acoustic), probably nothing to fret about but it does show you need a mic to tell whats is going on
A matter of judgment or taste, but I think the Keystone and Titan 48 seem to be at the bottom of the pack, at least for lowest range. But they aren't at the bottom as you go up the scale a bit.
Again, thanks for the data.
B.
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Footnote about understanding the "normalized" THD display
The THD normalized display is helpful for comparing different speakers AS IF they were all EQ'd flat from whatever is their normal flat-voltage output level. Yes, in theory you could do that EQ. In practice, all the subs can be truthfully compared in the range of, say, 40 Hz and up where they all have comparable output.
But can you actually push all of those subs to produce strong output at, say, 25 Hz? The distortion WHEN PUSHED THAT HARD (and if they could even produce any note like that) would be substantially more distorted than what the curves show.
In short, you need to consider how loud that speaker is playing and how much distortion has been measured at that level. And that's the plain-vanilla THD display.
B.
The THD normalized display is helpful for comparing different speakers AS IF they were all EQ'd flat from whatever is their normal flat-voltage output level. Yes, in theory you could do that EQ. In practice, all the subs can be truthfully compared in the range of, say, 40 Hz and up where they all have comparable output.
But can you actually push all of those subs to produce strong output at, say, 25 Hz? The distortion WHEN PUSHED THAT HARD (and if they could even produce any note like that) would be substantially more distorted than what the curves show.
In short, you need to consider how loud that speaker is playing and how much distortion has been measured at that level. And that's the plain-vanilla THD display.
B.
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Hey Ben,
The above comment is not accurate.
The graph shows the distortion on a percentage scale, but it has nothing to do with EQing the speaker response to flat. This would change any speakers distortion results entirely. This type of data presentation makes it much easier to compare the amount of distortion from different speakers but the SPL and frequency response shape is not present on them and must still be considered.
You seem to have missed my explanation in the next post.
Each display of reduced/summarized information has different shortcomings. Even noting the shortcoming both of us discuss, the range up from 40 Hz can be reasonably compared with a normalized view and the rest with the needed pinch of salt.
B.
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Well, you do have the 18NLW9600 at your disposal? - replace and re - measure your enclosure - driser, loaded with 18Sound 18NLW9600, 4 Ohms, rated 1800 W RMS, 3600 W program.
Divide and conjure!!!
looking at my impedance curve from 60 - 80Hz it's fairly low impendence, there's a lot of power being delivered? - from 35 H -< ish the impendence is rising quite rapidly hence not a lot of power being delivered. - Of course, the HP filter is rolling all of that off or should be!! - there's a good reason the B&C Speaker is so well respected ... Trust me - that 3 dB and some comes in handy later on in the night ...
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