Project M2 DIY Thread

[Earl K]

Did you ever see how close these were to each other?

Scott,

If you'd like some help in designing a passive HiPass filter ( for a 2450SL mounted to a M2 waveguide ) just ask.

There are indeed some usable measurements located within this thread which gives one a head-start for roughing-out a design.

( To move it forward beyond this ) you'll need to use REW to capture some response sweeps so that they can be compared to those already done by LHF member "sebackman" .

You also need to create ( with REW also ) an impedance sweep of a 2450SL driver on an M2 W-guide ( + then export that as an .zma file ).

Then anyone ( with network design software ) can conjure a custom HiPass after a bit of manipulation.

Having said that ( plus after using Robh3606 + sebackman's pics, then tracing them, + then turning those into frd + zma files ) here's what a network would look like ( following LEAPs lead in using 3-pole bump filter for the high-pass ).



For the sake of comparisons Robs 476mg is in black ( raw fr + with his @ network ), the 2450SL is green ( raw ) + blue ( network ), & then the ( raw ) 2451Be is represented in red.
- FYI, the traces from sebackman aren't that believable below @ 1000hz.

I had to use Robs 476mg impedance file as a standin for the 2450SL ( which is a real no-no in the design world > but it's a bit better than having nothing to work with ).
- That's another reason what you see above you can't take to the bank.

You might locate a 2450SL\M2 .zma file from sebackman ( since he had made an impedance file some years back ) .

The true value of this exercise is you that get an idea of the parts count ( of passives ) needed for a flat-ish hipass ( plus the need for sa couple PEQ, LCR notch filters ) .

[srm51555]

Hi Earl, thank you for taking the time to respond.

I would love to design a passive crossover with someone here but unfortunately with young children that is not a possibility for me right now. Out of Respect to those who would help me I wouldn't feel right unless my schedule was open. As my youngest gets older I do feel there is time at the end of the tunnel. One day I would like to try for knowledge sake at the very least.

For me this whole passive thing on the M2 started by reading Greg Timbers post here:
http://www.audioheritage.org/vbullet...l=1#post386898
and
https://positive-feedback.com/interv...g-timbers-jbl/

Another member suggested (before I posted) for me to use an existing network someone has already graciously posted, e.i Rob's or Zilch's and smooth out the rest with eq.

After reading the interview article again today he mentions something about eliminating the group delay at the crossover points by using FIR correction that I must have originally passed over on. Until now I assumed his system was passive for the compression drivers and active on the woofers, hence why I was thinking passive on the top end.

Thanks,
Scott

[Earl K]

Okay Scott, understood,

Here's a revision of what I previously posted ( my last kick-at-the-can for now ).

I created & used 2 considerably more accurate ( frd + zma ) files to work from ( > gleaned from "sebackman" pics located earlier in this thread ).

This Hi-Pass would allow for a crossover point just slightly under 800hz.




This version uses a variable ( 8ohm ) LPad ( represented here as R8 & R9 ).

R2 is best replaced by a 30-35 ohm potentiometer ( for flexibility ) .
- Adjusting R2 allows for a HF roll-of slope ( the grey trace = 30 ohms for the R2 value ).

The 3-pole bump filter has been adjusted ( as have the "Q"s of the 2 notch filters ) .

A full single-channel passive workup ( for LF + HF ) would be handy for those not wanting to go all DSP.

Obviously, that'll have to wait till there's more interest.

[srm51555]

Hi Earl,

This is a great addition to the thread, thank you for taking the time to post this for me and others. I do know of one other person this may be helpful for.

Future reference question - how close would this be to the 4367's low pass. The reason I ask is if someone 2 years from now wanted to build a passive crossover with a 2216nd-1 would it work out OK? It's OK it wouldn't but I figured the question may come up.

Thanks,
Scott

[Earl K]

Hi Earl,

This is a great addition to the thread, thank you for taking the time to post this for me and others. I do know of one other person this may be helpful for.

Future reference question - how close would this be to the 4367's low pass. The reason I ask is if someone 2 years from now wanted to build a passive crossover with a 2216nd-1 would it work out OK? It's OK it wouldn't but I figured the question may come up.

Thanks,
Scott

Hi Scott,

I really doubt that the 4367's low pass would successfully mesh ( just as is ) without modifications to either (or both ) the hipass & lowpass sections.

Additionally, I don't know the parts values for the 4367's lowpass circuit ( I looked yesterday but couldn't locate a populated schematic ).

( Some clarification ), the previously posted Hi-pass is relevant & best used within a active hybrid -biamp situation where the lowpass is all electronic but where the hipass section is all passive (ie; the horn section is run off it's own amp but hi-passed and contoured passively > this is how I run my system, btw )

FYI, I've already starting working on a low-pass ( using JBL's published info > meaning, at this time it's all just "blue-sky" until I get some real measurements of a 2216nd in a tuned enclosure ).
- And that most recent published Hi-Pass ( post #618 ) has already been modified ( in just about every aspect ) to work with this new low-pass.

[Integra]

Hi all,
If possible please share the cabinet drawing files.
will be good in metric system.
Evgeniy.

[macaroonie]

If you Google. 'JBL M2 dimensions' and use image search you will see a diagram of the speaker with dimensions in metric.

Welcome to the forum 👍

[sguttag]

Even better...go to the first post of this thread and at the bottom are links for internal and external dims as well as links for handy photos of both DYI and genuine M2.

[Integra]

Thank you all for directions.
Do is by myself...

[rodec]

Even better...go to the first post of this thread and at the bottom are links for internal and external dims as well as links for handy photos of both DYI and genuine M2.

Hi Integra,
I found out all information from sguattag's link post #1.
Use the real speaker dimensions, horn or external connection for the rest.
After, if depends how you want to build the cabinet, it may changes the dimensions of the various cuts.

[rodec]

I just got today Bss blu-100, I already have blu-50 which I`m using about two years in my M2 setup.
I tried to make Bss tuning file from Jbl official site with audio architect based on readings on posts here in forum and entire wold wide web!!
but it doesnt work like the original file! something is missing or I dont know how to workout.

We all know that official Bss file is locked! but I need to add a Danley Dts-10 sub woofer along with M2, which has to be tuned too with parametric EQ, High-pass filter, delay...
If anyone who has Bss piece, managed to unlock it or make it work no matter LA or AA please published here or send it to me over PM???

Thanks

Hi agronk,
Any progress?
I am in a similar situation, move from london architect with the official M2 setup file to audio architect but the file is not compatible (or I did not find).
Don C demonstrated some steps to move in this direction : http://www.audioheritage.org/vbullet...M2-horns/page7

[dprice]

[QUOTE=Earl K;420490] FYI, I've already starting working on a low-pass ( using JBL's published info > meaning, at this time it's all just "blue-sky" until I get some real measurements of a 2216nd in a tuned enclosure )./[QUOTE]

Earl K - Do you still need 2216Nd measurements? I can run FR and impedance sweeps on my DIY M2s if that will help you.

[lesliew]

I just got today Bss blu-100, I already have blu-50 which I`m using about two years in my M2 setup.
I tried to make Bss tuning file from Jbl official site with audio architect based on readings on posts here in forum and entire wold wide web!!
but it doesnt work like the original file! something is missing or I dont know how to workout.

We all know that official Bss file is locked! but I need to add a Danley Dts-10 sub woofer along with M2, which has to be tuned too with parametric EQ, High-pass filter, delay...
If anyone who has Bss piece, managed to unlock it or make it work no matter LA or AA please published here or send it to me over PM???

Thanks

Hi agronk,
Any progress?
I am in a similar situation, move from london architect with the official M2 setup file to audio architect but the file is not compatible (or I did not find).
Don C demonstrated some steps to move in this direction : http://www.audioheritage.org/vbullet...M2-horns/page7

There were a series of posts over on AVSforum the last few days showing the parameters from London Architect for the M2, 708, 705, they might be of help.

https://www.avsforum.com/forum/89-sp...l#post57945990

[rodec]

There were a series of posts over on AVSforum the last few days showing the parameters from London Architect for the M2, 708, 705, they might be of help.
https://www.avsforum.com/forum/89-sp...l#post57945990

very interesting posts, thanks lesliew.

[Earl K]

FYI, I've already starting working on a low-pass ( using JBL's published info > meaning, at this time it's all just "blue-sky" until I get some real measurements of a 2216nd in a tuned enclosure ).

Earl K - Do you still need 2216Nd measurements? I can run FR and impedance sweeps on my DIY M2s if that will help you.

Real measurements are always most welcome.

Thanks for the offer!