What is the correct porting for the L300 cabinet if 2216 nd1’s are installed?
What is the correct porting for the L300 cabinet if 2216 nd1’s are installed?
If it's already tuned to be ~30Hz (say 5-6ft3 vol, 4" long x 4" diameter port), I'd just start with it as-is (running through some scenarios).
I would expect that to be fairly close to neutral (no 50-60Hz bump and not unnecessarily rolled off). Can be surprising how much a tuned box influences things.
You could tune it for more thump (and less low bass) by shortening the port, but I think you're in uncharted waters -and- there's no one
particular correct answer.
I'm running ND-1s in my L200s.
I was prepared to make port changes, but found I get excellent sub-30hz response as is - but the L200 ports (LE15Bs) are different from the L300s, I believe. (IRCC, the calculators showed them to be tuned to around 28hz on those boxes.)
With a bit of EQ, I get very close to 20hz with them.
Several of us have done these L200 'mods' - documented over on audiokarma.
FWIW, the ND-1s completely transform not only the LF, but also lower MF, of these things.
Highly recommended - have fun!
I have no idea what the difference is between the ND and ND-1, but hearing the 2216ND in a pair of M2s really impressed me.
I'm sure that either version will be an upgrade over the 2235H (especially in the lower mids) and I doubt the port tweaking required is that drastic.
Widget
Good advice Ivica. About 1.5 meters. At tweeter level. Still a little sickout at the mid crossover. Stock L-pads are at the zero position.
My comments are not from measured data. I did substitute 2216nd's that I had purchased several years ago for the 2235's in a pair of 4333B's. I also replaced the existing crossovers with charged coupled Nelson Pass/Zonker92 boards. I have listened to these for several months now. My opinion is, the 2216nd's are a serious step up from the 2235H's. The lower midrange now matches the mid horns in clarity. The mid bass is smoother in that I can clearly follow the bass instruments. Also smaller drums have a snap that was lacking with the original 2235's. Low bass around 30Hz seems to be down a little, but still good. Voices are much clearer and more natural compared to the original crossovers and drivers. If you have the bucks, the 2216nd is the way to go.
Thanks for your testimonial John. I follow all the comments ( over at AK ) praising this upgrade.
I'm sure I would like that woofer since I value clarity over out-right ULF extension.
I think your 2216nd is another positive development ( in large signal track-ability ) that started way back in the early 90's with the introduction of the Me150H.
Plot of the freq. response with the new 2216nd. No changed to the crossover. Measured @ one meter. These sound and measure like plug and play. With Nelson Pass crossovers.
Hi johnlcnm,
I think that for such large box speakers measuring from about distance 3m would show more realistic results.
Applying only 1st order network (instead of 3rd applied by JBL) for UHF (2405) would introduce strong 'comb filter' effect (as can be seen).
regards
ivica
It would be interesting to compare these modified 4333's to the 4343's. It can't happen here in the outback, but the folks living in the old JBL stomping grounds might have that ability. This mod. makes me hanker for a new pair of 4367's! It was Nedseg and some others over on audiokarma that planted the seed in my head to try the 2216's, although they used the dash one versions. I am running the pads set to zero, though the 2216 is specified as 2dB more efficient then the 2235.
Yes, a lot of interference. The setting is not a good one for measurements. Looking at the spectrum, I'm a little concerned about the anomaly at 700Hz. I need to check the polarity of the mids and woofers. I did reverse the input to the 2216nd's, as their phase should be the reverse of the former 2235's. The crossover outputs to the mids were not marked. I did meter back to the crossover inputs and mark them. I need to make sure the phase is reversed between those two drivers.
Hi johnlcnm,
If You measure the distance from the mic and center of the bass driver You can get the length distance differences, not to mention floor surface influence. So some measurements can be done while speaker box is laid on its back side, and put the mic on top over it, as high as possible away from the speaker.....
regards
ivica
Thank you Mr. Widget!
I accumulated pages and pages of links and references over the course of several years, and chose the ND-1s.
I don't really recall why now; perhaps b/c the 4367 does not require DSP, or I was thinking worst case I could buy the 4367 LF crossover if active xovers didn't work?
The technical differences I could find documented seemed minor.
In any event, at the time I purchased the first one, they were the same price as the ND.
However, the last ND-1 I purchased was quite a bit more expensive (~$800), so I doubt that whatever difference there is, is worth it now.
Alobar published some of his REW measurement results on AK, which are nearly identical to what I've measured (also very similar to the measurements made with the Venu360 RTA).
I'm crossing over to the horn at 1150hz, I think he's running the ND a bit higher.
And, while the dramatically improved mids are impressive and a pleasant surprise, it has to be said that the bass response improvement (esp from the - original 2216! - le15b) is night/day.
From muddy & boomy to clear, deep & precise - crisp?
I spent a lot of time in my youth around 4350s and L300s, and was continually critiquing the L200's poor bass/lower mid-range (I did the 077/N8000 upgrade shortly after purchasing them in '74) - this now brings them up to par finally. Worth waiting nearly 50 years for?
And so simple to do - a straight drop-in replacement, and DSP makes the crossover issues go away.
The 4645C sub I have matches the 2216ND freq response (up to a point), but trades off 'cleanliness' for Power - makes for an interesting combo.
These woofs make the modified L200 3-ways truly full range.
PS. And a huge Thanks to SRM51555 (Scott) - and all the others who contributed to those threads - whose M2 DIYs really inspired me to take the risk.
He has heard my upgraded L200s, and I think its fair to say he was favorably impressed.
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