Similar to this? https://www.roomeqwizard.com/help/he...asurement.htmlOriginally Posted by Earl K
If so I'll need to order the non-inductive resistor.
Thanks,
Scott
Similar to this? https://www.roomeqwizard.com/help/he...asurement.html
If so I'll need to order the non-inductive resistor.
Thanks,
Scott
The DATS-V3 from Parts Express is a lot simpler to use and virtually bullet-proof ( from what I see in the forums from new users ).
OTOH, I see many people fumble putting together a working jig ( for use with REW ) for a myriad of reasons.
If those REW instructions are correct I should be able to figure it out. I've got some good plots I can compare mine with to see if mine are correctly done.
I don't plan on designing any more passive crossovers after this, next build is a know design.
Thanks,
Scott
The passive crossover progress has slowed due to other house projects, mainly converting half of the current listening room into another bedroom.
The parts were ordered for the impedance plots but that's about it.
Thanks,
Scott
Hi Earl,
Sebackman was extremely gracious and provided the impedance curve he had made a while back. The file zipped is 6mb so too large to attach. What is the preferred method for transfer over to you?
Thanks,
Scott
Hello guys,
I have not looked at this thread for a while.
There appears to be a number of partial or un answered questions.
4367 network mods - what changes on 2450 SL
M2 impedance curves. Stock M2 driver, 2450 SL
M2 response curves. Stock M2 driver, 2450 SL
I have the capacity to do some free space outside measurements and ground plane measurements.
With some good data l can then offer you a heads up on (1) the passive network EQ and (2) passive crossover.
If you are unable to do outside measurements l suggest a near field measurement of the horn about 100mm (4 inches) beyond the mouth with the mic attached to a thin tube like a fishing rod supported by a camera tripod.
There are three ways to measure.
(1) With the enclosure free standing
(2) with the enclosure on its back on the floor
(3) with the enclosure on its side on a smooth floor surface. A timber or tiled floor will do. Or place a sheet of thin plywood on carpet. In this case the mic should be placed on the floor about one metre from the wave guide if taking the measurements inside. A bit closer will work if you tilt the enclosure forward so the throat is on axis with the mic.
Horn-Wave Guide EQ
A couple of general points. The EQ seems to be the stumbling block and understandably so with all the diy iterations. To provide clarity l recommend treating the crossover and the EQ as separate actions that can have one or more solutions.
(1) If you are attempting to do an active EQ and active crossover the 10db resister pad is essential to avoid noise and dsp artefacts contamination of your musical enjoyment. It’s just one of the trade offs of using an active approach.
(2) Diy passive EQ. This approach is quite difficult and inflexible if you need to make further modifications without a simulation using measured data. Painfully so. It will require repeated measurements after spending time on guesswork changes.
(3) Do NOT get tangled up on filling in every minute response pot hole. This is diy so don’t beat yourself up on commercial marketing hype & perfection. Most of that you won’t hear at home anyway.
Wave Guide/Horn EQ procedure
If using dsp or an analogue EQ such as a parametric EQ like a Drawmer 1973 or UltraCurve there are two basic diy audio approaches
(1) Attenuation - this is your friend
It involves a low shelf EQ cut around 3-4 kHz and then adjust the attenuation and frequency until the response starts to level off. The idea is to obtain a 6 db per octave attenuation correction of the mid frequencies. Then apply low Q Bell Curve correction cut to smooth the response with another EQ band in the middle of the pass band.
In comparison the passive EQ is like nibbling away at discrete aspects of the overall response. The individual passive EQ filers interact with each other so it’s a complicated thing to arrange.
# Forget about the JBL dsp EQ settings. It will only confuse you. Your in diy mode and your on your own.
You can still use a passive crossover network this way and one stereo amp but not have to anguish over the EQ step and you will have more control. It should not take more than one afternoon to dial in. An Ultra Curve is another EQ tool option.
(2) Boost
Firstly turn down the input level about 10db. Use a high shelf boost starting at 3-4 khertz and adjust the boost on the shelf EQ and watch the HF response lift and flatten. Then apply a low Q parametric cut to the mid pass band to further flatten the response. Avoid using more than 10 db of shelf boost. Apply a Q low Bell Curve cut to push the mid pass band down. This approach will reduce noise and possibility of headroom overload.
Use a passive crossover based on the 4367. I will investigate this further. A 4th on the woofer and an acoustic 4th order on the wave guide/ horn (not electrical okay).
I will post a follow up on this over the next few weeks.
This is the sort of thing l was referring to. A tool that in your diy loudspeaker scene would be incredibly useful with all your projects.
I have not used any of these particular parametric EQ units. That said they are right on the money for free hand tweaking of specific horn EQ requirements making the process of setting up your horn quicker and more convenient than sweating over a passive EQ. Some are reasonably priced like the EQ73premier.
I will post an example of a two band EQ over the weekend l used for the Everest horn.
None of this diy audio stuff should be a drama that takes months of figuring out and screwing around!
It’s meant to be fun. Not a pita.
https://www.storedj.com.au/drawmer-1...tric-equaliser
https://www.sweetwater.com/store/det...ue-1-equalizer
https://www.storedj.com.au/behringer...q-and-analyzer
https://www.sweetwater.com/store/det...etic-equalizer
https://www.sweetwater.com/store/det...a-xfilter-rack
https://www.sweetwater.com/store/det...-eq-73-premier
Attached are screenshots comparing the native response of a JBL Everest horn, a passive crossover voltage drive with an overlaid active EQ and passive crossover voltage drive with accompanying schematics.
(1)The simple terms the full passive crossover does both the crossover function and the passive EQ. Note the complexity of the passive network and the number of passive EQ circuits. Optimisation is nearly impossible without a lot of expertise and experience.
(2). The active horn EQ is a basic two stage dip EQ and a low shelf attenuation EQ stage. This would be placed between your preamp and power amplifier. The actual passive crossover network remains and performs the high pass crossover function. The passive network is a relatively easy task and can be determined using a crossover switch box as described in Greg Timbers recent interview on Erin’s Audio Corner.
(3).Note the fixed passive attenuation before the driver. This is of vital importance to maintain the signal to noise ratio like the full passive network. Otherwise the dynamic range of your system will be compromised.
I was able to tune the active horn EQ within 10 minutes. Therefore tweaking of four parameters would result in a curve indistinguishable for diy purposes.
I have shown a simplified realisation of the schematic to demonstrate the simplicity and power of analogue active EQ.
If you are not prepared for the complexity of a full dsp M2 or other project then this is a very good option. It requires far less effort than a full passive crossover and EQ network and gives you immediate feedback and control over your adjustments and results. The key for diy loudspeaker users is that you can accurately sculpt the final response quickly and very accurately/ easily to your liking.
Of interest to some is that there is no dsp conversion or dsp processing involved. Such analogue active EQ is used in mastering of all recordings before they ready for cd, streaming or vinyl format. Dsp mastering is used but is not regarded as authentic. A plug in is just that. It mimics a real sound or an effect. It’s not a replacement. That is why analogue mastering EQ is used.
(4) Note either the REW or Dayton frequency response measurement kit is required.
Please note the schematic is not ready for the real world and is for illustration only.
If there is sufficient interest and enthusiasm l might consider putting together a kit for those things interested.
Yoda
Scott,
Just what type of file are you trying to upload?
( .frd and .zma files are extremely small > in the kb range ).
Use the export menu within REW to create .frd or .zma files of your captured data ( usually exported as .txt files till the file type is manually changed).
Alternately, setup a Google Drive virtual drop-box ( up to 15GB of storage is free ) . One can enable selective sharing for specific files.
Hi Ian, thanks for the posts. My original thoughts were for a passive on the M2 waveguide with a 4" compression driver only. Unfortunately I sold the D2's so would be unable to provide any useful data. When needed I would be able to take measurements either outside weather permitting or with the enclosure on the floor. A passive for the 4" compression drive and 4367 waveguide would be neat to have but do not have that waveguide, yet.
I do have the 10db pad in my active setup. My current DSP settings on the waveguide are consistent with others. I haven't looked at in a long while but if I remember correctly it something like a notch at 1k-2k and a shelf at 8K-9K. I found fixing other points didn't sound as natural as I'd like as you mentioned.
For 3k-4k eq, this is something that I feel I can't get correct in my setup due to how reveling these speakers are. Also my room is just ok so there is that in the circle as well. It seemed like a passive would pola-yolk all options except 2 knobs for adjustments.
more to follow
Thanks,
Scott
Hi Earl,Scott,
Just what type of file are you trying to upload?
( .frd and .zma files are extremely small > in the kb range ).
Use the export menu within REW to create .frd or .zma files of your captured data ( usually exported as .txt files till the file type is manually changed).
Alternately, setup a Google Drive virtual drop-box ( up to 15GB of storage is free ) . One can enable selective sharing for specific files.
The file is a .tzz
Thinking about it some, I'd really like to figure out why my HP desktop computer isn't picking up the microphone input from REW during the shorting test. The front headphone jack is a combo headphone/microphone which wont work. I suspect it's also combo on the back as well, but it's not clearly labeled. I'm going to order a splitter and try again before I use Rob's data. I'd really like to learn than ask when possible, but still grateful for the help on here.
Thanks,
Scott
Hi Scott,
Got ya.
Just looking at your recent posts. What drivers are you currently using?
It seems you have tried the stock M2 drivers and moved on. I haven’t personally set my M2 horns up yet as l am buried in some other work right now. You seemed stuck. But l note that due to the wide dispersion on the horn you “may “ need to globally attenuate the horn response down overall by about 1.5 db or more ref the 2216nd. Or taper the response down to suite your conditions. This may defy convention.
Why?
Due to the very wide power response of this particular wave guide the on actual on axis response while useful for crossover design is not necessary appropriate for listening in a domestic situation where you have six flat un treated surfaces.
Trust your ears not the measurements because your ears are hearing the whole room. Not just the direct on axis response if that makes sense. The D2 driver is possibly more surgical and analytical than what your used to and that is why l posted about analogue EQ. DSP EQ can also cold, analytical or sterile and that is also part of the story. Not really appropriate in the hifi world. So you might be having difficulty acclimatise to the presentation.
Back to the network what 4313 alluded to was a network that allows you to manually adjust an L pad back in the 2-3 khertz area just like the 4430 crossover schematic. It also has a HF brilliance LPad. These L pads enable easy adjustment so you can make adjustments and listen. That is the key.
It’s a very simple network that you can play with. It won’t be technically dead flat. But that l don’t feel is what’s important in your space at the moment.
Trust your ears not your on axis measurements at the moment. Ruler flat response on paper is the icing on the cake. But not what’s in the cake. You need to get the mix right. If you look at the M2 overall EQ JBL significantly doctored the 2216 bottom end to give the presentation balance. It’s like a see saw. Too much mids and highs means your ears need to turn up the bass tone control to make it sound right. First world problem.
The whole deal on it must be flat goes right out the window because your ears are receiving the total sound power and they are saying it’s way too hot. Simply dial back the treble and dial up the bass like a tone control so to speak. Don’t be locked into the rigid regime of obtaining a ruler flat response. That’s where perhaps the confusion is.
I hope this brings you some insight.
Ian
Edit Below is Robert H M2 passive network for the 476Mg driver. It is close enough for any conventional JBL driver. If you have a 16 ohm drive simply put a 20R resister in parallel with the drive and the network won't know the difference.
I have added 3 Lpads labelled in the attached schematic.
These L pads allow independent adjustment of 3 hertz Presence, 10K hertz brightness, and overall Horn level.
Technically an 8 Ohm L pad can be wired up for an 8 ohm trimmer or a 33 ohm trimmer as it has two independent wire wound tracks.
This embodiment will enable on the fly adjustments I mentioned above so you can listen and tweak just the way Greg Timbers does.
As I said earlier the ruler flat stuff is really just finessing the optimisation once you have a ball park listenable system which is the whole idea of using classy drivers.
Notice I actually made the effort to upload nice clean pdfs...LOL. Enjoy your weekend where ever you are.
If you are trying to do a 2450SL on the M2 it's no big deal. Keep in mind the 476Mg is a 16 ohm driver . I don't know what kind of crossover simulation software you have but this schematic should get you close on the compensation. As far as the rest of it I am crossing at 700Hz and my drivers are out of phase.
That was the best summing I could get with my cabinets and driver spacing. You may be able to get better so use as a guide only. You will need a series notch and one parallel for the EQ. You are going to have to play with the values in the series notch to get the on axis curve you want. Also if you look at my actual vs predicted you can see a droop at 10K not sure if it was a measurement issue of I should have tilted for a peak instead of flat. I went for as flat as I could get at the 700Hz crossover.
On the low end I built my cabinets tuned to 26Hz same as a B380 have a Q2 filter at 26 hz +6Db. Works great have useable in room response all the way to 20Hz doing sine sweeps
"I could be arguing in my spare time"
Hi Rob,
Sorry l stole your schematic. All the works been done so why do it again?
By making R2 a variable resister it’s quite straight for to dial in the 10khertz.
See my attachments
Same with the variable resisters in the voltage divider. Much more diy user friendly for everyone to share!
Good job on that schematic. Simple and very effective.
There are currently 1 users browsing this thread. (0 members and 1 guests)
Posting Permissions
Reply With Quote