jackgiff
Well-Known Member
I was thinking about financing a group buy of rubber bands, but if that failed a group buy of broccoli. Anybody in?
What kind of broccoli does the proper band come on?
If I Told You What It Takes to Reach the Highest High...
- Thread starter toddalin
- Start date
I was thinking about financing a group buy of rubber bands, but if that failed a group buy of broccoli. Anybody in?
What kind of broccoli does the proper band come on?
Actually, I find that while some broccoli has them, they are much more common on asparagus to hold the bunches together. They are purple in color. I think they are imported, so maybe you want a domestic source.
Maybe color coded like Holley accelerator pump cams.
I looked and I guess that we didn't get the measurements for the verticle on a plot.
The 2405s may have better verticle dispersion when you are right on axis with the slot as JBL measures it, but if that's not the case, it seems that the 24025 has better verticle dispersion off at an angle.
It seems that you can hear (and measure) small differences in the verticle angle of the 2405 that you don't hear with the 2402 dispersion pattern when off-center. I don't think you'll find that documented in the JBL literature.
Furthermore, better doesn't necessarily mean wider. It also means more consistant. Look at the big lump with frequency when the slot is used horizontally. It is not there when the slot is run vertically, and who doesn't run their slots vertically in a home/studio setting? As I stated, more sensitive to verticle placement.
BTW, Sorry AK's Grumpy. The reference to "Grumpy" was for the benefit of the LHF people where he is well known.
The 2402 is axisymmetric conical; the dispersion is the same at all angles. Comparing the "Todd-Modded" 2402-5 horizontal polars to the 2405 verticals is legit.
Given that the 2405 horizontal dispersion is wider than that of 2402 in the horizontal, as you have above conceded, on what basis might we suppose that its beamwidth would collapse in the oblique? JBL does publish the oblique polars for 2404H, and they appear to be a blend of the horizontal and vertical:
http://www.jblpro.com/pub/obsolete/2404.pdf
On this basis it would appear more reasonable to assume that the 2405 oblique beamwidth would be wider, not narrower, than the on-axis vertical alone, as it is being "enhanced" by the wider horizontal off-axis, and, "Yes," there are likely to be audible differences in the beamwidth, but with 2405 being wider, not narrower than 2402-5 in the oblique.
Uhmmm, the slot is vertical for both measurements. The arrows indicate the direction of rotation, lateral vs. vertical. You are claiming wider dispersion for the 2402-5 with a supplemental rubber "diffraction device" based upon your "band within a tube" analogy. Show us the data.... :thmbsp:
I have just taken a comprehensive look at the published JBL frequency response curves and Widget's, Robh's, and my measurements of these, and do not find any evidence substantiating this contention. What I DO find is that the ring radiator diaphragm does not appear to be operating pistonically above ~4 - 5 kHz, and that the frequencies of the complex of resonances in the VHF region vary widely, even among different samples of the same device, as is revealed by the impedance measurements:
http://www.audioheritage.org/vbulletin/showthread.php?p=62922&#post62922
Additionally, as I have earlier illustrated, the location of the native "notch" in the response in your specific range of interest also varies widely among different samples of even the same model device:
http://www.audioheritage.org/vbulletin/showpost.php?p=84719&postcount=48
No, Todd, this is YOUR gig, and it's YOU making these random assertions, and thus, it's YOUR responsibility to substantiate them. Once you do that, then, if others can replicate your results, they validate your findings.
2402 is an exponential horn. 2404 and 2405 are both diffraction horns in the horizontal. Do you not see the similar vertical diffraction slot in 2404? Truncate it on a bandsaw and you've got substantially the same geometry.
Now, you're makin' stuff up. :nono:
2404 and 2405 are both 105 dB/1W/1M. 2402 is 110 dB with the stock diaphragm, you've already determined that sticking the 2405 diaphragm in it lowers the output, and the "Todd-Mod" lowers it even further, as I recall.... :yes:
"No, Todd, this is YOUR gig, and it's YOU making these random assertions."
No it is your assertion and flies in the face of physics. The 2405 actually only gives up a few dB to the 2402 (only 1-2 across the entire band and maybe 4-5 at 10kHz), a lot less than is lost in the 2404 that gives up about 10 dB to the 2402 on axis
If the 2402 and 2405 have near the same volume level on axis and the 2405 has greater dispersion in both the verticle and horizontal, it MUST give up volume in the oblique, simple physics.
If you insist it doesn't, prove it as this is your assertion, and no one elses..., not even JBL. Obviously you are "out of your element here."
No it is your assertion and flies in the face of physics. The 2405 actually only gives up a few dB to the 2402 (only 1-2 across the entire band and maybe 4-5 at 10kHz), a lot less than is lost in the 2404 that gives up about 10 dB to the 2402 on axis
If the 2402 and 2405 have near the same volume level on axis and the 2405 has greater dispersion in both the verticle and horizontal, it MUST give up volume in the oblique, simple physics.
If you insist it doesn't, prove it as this is your assertion, and no one elses..., not even JBL. Obviously you are "out of your element here."
Click the links, Todd, and fill in the blanks:If you insist it doesn't, prove it as this is your assertion, and no one elses..., not even JBL. Obviously you are "out of your element here."
2402 = _____ dB/1W/1M
2404 = _____ dB/1W/1M
2405 = _____ dB/1W/1M
http://www.audiokarma.org/forums/showpost.php?p=2493577&postcount=41
Kegger
R.I.P. 1/12/1966 - 6/1/2017
When using these in the home enviornment does the dropped output matter?
---------
Another thing to toss out there, some feel and strive for the less electrical parts
in the path way of building things, sure if your using equipment with 200 - 300 or
more parts already in the path then the speaker is probably no matter but if your
at dozen or less like some simple systems try an strive for from source to speaker
connection then the "band" approach verse the compensation an L-Pad parts may
be a welcome way to go.
---------
Another thing to toss out there, some feel and strive for the less electrical parts
in the path way of building things, sure if your using equipment with 200 - 300 or
more parts already in the path then the speaker is probably no matter but if your
at dozen or less like some simple systems try an strive for from source to speaker
connection then the "band" approach verse the compensation an L-Pad parts may
be a welcome way to go.
Not one whit, basically. How many woofers can do 105 dB?
Against compression driver mids, it's a good match, particularly if you comp the mids flat to the XO frequency. Passively, you're likely going to have to pad down the mid/high combo to balance with any but the highest-efficiency woofers.
It's pointless. Nobody's used 2402 in a serious high fidelity design for 30 years.Another thing to toss out there, some feel and strive for the less electrical parts in the path way of building things, sure if your using equipment with 200 - 300 or more parts already in the path then the speaker is probably no matter but if your at dozen or less like some simple systems try an strive for from source to speaker connection then the "band" approach verse the compensation an L-Pad parts may be a welcome way to go.
Likely fact is, Todd could sell his 2402s and break even getting 2404s or 2405s to replace them. It's obvious he has an "agenda" here, the same one he's pursued for several years now.... :yes:
Whew, that's a relief. I was worried about Dave for a minute there.
Really funny thing is that his name is also Dave.
OK. Included are the plots we obtained yesterday. I appologize for the poor quality. They did not scan well and may hardly show up after further processing by the host server.
We did on-axis, 15 degrees, 22.5 degrees, 30 degrees, and 45 degrees. All readings were taken at 1 meter and there was no crossover used; just a 12 mfd cap to protect the tweeter.
First the 2402. This is what we are starting with.
Next is the 2405. This represents the goal in frequency response from the 2402 shown above. It is recognized that these levels will net be attained off axis.
This one is the 2402 with the 2405 diaphram and no band. Note that from on axis to about ~10 degrees, the curve is similar to that of the 2405 with the exception of a ~2 dB dip in the 8-9kHz range as I had noted in the past. Still, the response is much better than with the 2402 diaphram in all portions of the spectrum above the crossover frequency.
This last sequence is the 24025 with the band. We did not try for the flattest response or most like the 2405, just a somewhat modified curve to see the effects of the banding. Note that it smooths out the humps in the 10-20kHz range while shifting the peak frequency up the band.
We also did the impedience runs with and without the bands. While the bands add some lumps, they are well below the frequency area of concern and the impedience never goes out of its unbanded range.
Ultimately, after my 2402 tweeters are all fitted with the 2405 diaphrams, I'll decide whether to band them and adjust the banding to best work in the system at the proper placement.
Guess that about does it guys.
We did on-axis, 15 degrees, 22.5 degrees, 30 degrees, and 45 degrees. All readings were taken at 1 meter and there was no crossover used; just a 12 mfd cap to protect the tweeter.
First the 2402. This is what we are starting with.
Next is the 2405. This represents the goal in frequency response from the 2402 shown above. It is recognized that these levels will net be attained off axis.
This one is the 2402 with the 2405 diaphram and no band. Note that from on axis to about ~10 degrees, the curve is similar to that of the 2405 with the exception of a ~2 dB dip in the 8-9kHz range as I had noted in the past. Still, the response is much better than with the 2402 diaphram in all portions of the spectrum above the crossover frequency.
This last sequence is the 24025 with the band. We did not try for the flattest response or most like the 2405, just a somewhat modified curve to see the effects of the banding. Note that it smooths out the humps in the 10-20kHz range while shifting the peak frequency up the band.
We also did the impedience runs with and without the bands. While the bands add some lumps, they are well below the frequency area of concern and the impedience never goes out of its unbanded range.
Ultimately, after my 2402 tweeters are all fitted with the 2405 diaphrams, I'll decide whether to band them and adjust the banding to best work in the system at the proper placement.
Guess that about does it guys.
Davesnothere
New Member
Hi folks. I've not hung out here for awhile, but was encouraged to repost some
plots for completeness and readability. I do -not- have CLIO, but have been
using FuzzMeasure for some time (currently v3.1.1) with an Earthworks M30
and MOTU Traveler (multichanel A/D, D/A, mic pre), with fairly comparable
results.
Measurements were made at a measured 1m, with a marked string and
protractor to ensure at least a fair level of consistency/accuracy.
I think Todd has described the testing as well, but if there are any questions I'd be
happy to try to answer them.
First is the banded Alnico 2402(075) with the JBL 2405 diaphragm
measured at 0, 15, 22.5, 30, and 45 degrees horizontal
(we went back and did 22.5deg, as 30deg looked ... odd).
Next is -one- example of a stock Alnico 2402 with stock diaphragm.
Then 2405H plots (units are mine, NOS from JBL).
Horizontal and then vertical.
Lastly is a plot overlaying the first plot (banded, 2405 diaphragm) in RED,
vs. the same 2402 with 2405 diaphagm and no band in GREEN. IIRC, the
unit under test had a shim Todd installed for all cases of the 2402 with
2405 diaphragm.
Cheers.
plots for completeness and readability. I do -not- have CLIO, but have been
using FuzzMeasure for some time (currently v3.1.1) with an Earthworks M30
and MOTU Traveler (multichanel A/D, D/A, mic pre), with fairly comparable
results.
Measurements were made at a measured 1m, with a marked string and
protractor to ensure at least a fair level of consistency/accuracy.
I think Todd has described the testing as well, but if there are any questions I'd be
happy to try to answer them.
First is the banded Alnico 2402(075) with the JBL 2405 diaphragm
measured at 0, 15, 22.5, 30, and 45 degrees horizontal
(we went back and did 22.5deg, as 30deg looked ... odd).
Next is -one- example of a stock Alnico 2402 with stock diaphragm.
Then 2405H plots (units are mine, NOS from JBL).
Horizontal and then vertical.
Lastly is a plot overlaying the first plot (banded, 2405 diaphragm) in RED,
vs. the same 2402 with 2405 diaphagm and no band in GREEN. IIRC, the
unit under test had a shim Todd installed for all cases of the 2402 with
2405 diaphragm.
Cheers.
Attachments
Thank you, Dave. :thmbsp:
The last image, the overlay, shows what has occurred; Todd has flattened the 2405-5 VHF response with the Todd Mod, in this instance, most effectively at 15° off-axis with the particular band location on the measured unit, via midband attenuation, which is operating down to ~2 kHz. The slope of divergence from the native response appears uniform, and certainly suggests Wayne Parham's HF comp network, a cap and resistor in parallel, as alternative to the installation of the elastic band.
The 15° curve for the stock 2405 vertical polars appears to be MIA, so I can't really see if Todd Mod widens the vertical dispersion by comparison, but the 22.5° curve (green for 2405 vertical?) suggests not.
The last image, the overlay, shows what has occurred; Todd has flattened the 2405-5 VHF response with the Todd Mod, in this instance, most effectively at 15° off-axis with the particular band location on the measured unit, via midband attenuation, which is operating down to ~2 kHz. The slope of divergence from the native response appears uniform, and certainly suggests Wayne Parham's HF comp network, a cap and resistor in parallel, as alternative to the installation of the elastic band.
The 15° curve for the stock 2405 vertical polars appears to be MIA, so I can't really see if Todd Mod widens the vertical dispersion by comparison, but the 22.5° curve (green for 2405 vertical?) suggests not.
Davesnothere
New Member
re 15° 2405 vert plot... "my bad", the 0°, 15°, 22.5°, and 30° are all that are shown.
45° seemed outside of the 'rational use' window.
In that particular plot (2405H vertical)
0° - red
15° - green
22.5° - blue
30° - purple-ish
-dave
45° seemed outside of the 'rational use' window.
In that particular plot (2405H vertical)
0° - red
15° - green
22.5° - blue
30° - purple-ish
-dave
Davesnothere
New Member
Made for a more consistent presentation when going from seated to standing...
that much is true. 2405's are less forgiving in that regard, but are still my pref,
if available. Was a fun time over at Todd's, unwinding some of the questions.
Next time, I'm expecting more and less :nerd:
that much is true. 2405's are less forgiving in that regard, but are still my pref,
if available. Was a fun time over at Todd's, unwinding some of the questions.
Next time, I'm expecting more
and less :nerd: