M2 clone variation proposal

[rodec]

Hi all,

First post on a speaker's forum, I am a beginner, near Paris, and after reading the few thread about M2s, your nice stories pushed me to imagine owning a pair to listen to CDs, mp3, streaming and home theater.
I like pop, rock, beethoven like, modern jazz, voices.
I am not in a hurry, so it could take 2+ year to imagine understand few maths as well the wood working, fine.
My listening place is currently horrible, being not symetric. Perhaps in 1 year, I may have a dedicated room, let's see.

So, before ordering the standard M2 parts that represent some K$, I wanted your feedback if the D2430 is the only way to go, or if a "2450 + 2216" would make the job.
Is a 2450 better for home, compared to the D2430 for pro?

As I did hear none of them, I am looking forward to your experience and advices.
Thanks in advance.

[Don C]

2450 is 2 inch throat, larger then the M2 horn with it's 1.5 inch inlet.

[ivica]

Hi all,

First post on a speaker's forum, I am a beginner, near Paris, and after reading the few thread about M2s, your nice stories pushed me to imagine owning a pair to listen to CDs, mp3, streaming and home theater.
I like pop, rock, beethoven like, modern jazz, voices.
I am not in a hurry, so it could take 2+ year to imagine understand few maths as well the wood working, fine.
My listening place is currently horrible, being not symetric. Perhaps in 1 year, I may have a dedicated room, let's see.

So, before ordering the standard M2 parts that represent some K$, I wanted your feedback if the D2430 is the only way to go, or if a "2450 + 2216" would make the job.
Is a 2450 better for home, compared to the D2430 for pro?

As I did hear none of them, I am looking forward to your experience and advices.
Thanks in advance.

HI rodec,

Welcome to the Forum.
May be You think of 2450-1.5 or 2451 or 2447, or 476Be or 476Mg, but the problem would be UHF reproduction, except You would get Be/Mg diaphragms.
regards
ivica

[rodec]

Thanks for your prompt responses.

I tought about the 2450SL 1.5" (saw in the spec), read that 476be would be very difficult to find.
I did not imagine the UHF will be an issue.
I will check the price of be diaphragram and reread some threads where I remember have seen some measures.

[sebackman]

Hi,

You should be fine with a 4" (2447, 2450SL, 2451, 2452 or 2453) 1,5" driver with SL diaphragms. No real need for UHF with those diaphragms just some tweaking in the DSP. The 243* drivers do not seem to work equally good on the M2 WG

However, M2 is a system with the specific BSS DSP, the JBL settings, the cabinet and the specific drivers. If you alter any of this it is no longer an M2 system and the result will be different.

You may very well like the new system and be very happy with it, but an M2 it is not.

I have tried many drivers on the M2 waveguide (I got my first pair of M2 WG’sin early 2015) and my preference is the 24XX-sl drivers on a stand-alone basis. The Be drivers may sound a little “closer” but the early drop off in frequency and IMHO need for UHF support makes the SL a better choice. However, if you add the JBL M2 factory settings D2 is a better/easier choice unless you spend a lot of time on measuring and testing.

Us mere mortals cannot expect to achieve the same level of system quality as achieved by JBL with thousands of hours work going into the M2 system.

If you have the 4” drivers go with them but expect to put in many measuring/listening hours to get them working. If you need to buy drivers get the D2’s and be done with it.

Having said all that, I built a pair 2-ways with with LE1400H woofers, M2 WG’s with 2450SL cores (476Nd diaphragms), BSS DSP with tweaked JBL M2 settings and they sounded wonderful.

I’m also building a system with 2451Be (Truextent) on M2 WG’s and as Iveca said due to them falling off early I’m going to use 045 UHF drivers with them. They will definitely not be M2 clones but have a potential to sound pretty decent.

You choose. The easy way with predictable very good outcome = build faithful M2 clones with BSS DSP, or go you own way and expect quite some man hours and with the possibility to get very good result.

Kind regards
//Rob

[pos]

Hello Rodec, welcome to this forum, and to this hobby :)


I am not in a hurry, so it could take 2+ year to imagine understand few maths as well the wood working, fine.
That's the spirit :D

[rodec]

Thanks all, I did not expect a so active forum with fast replies, wonderful!

I quote this, because I was afraid to get it: "You choose" . Thanks anyway ;-)
Certainly a good risk management, take a proven "open" association, and focus where you have more flexibility.

By default, I did not imagine to make a 100% M2 clone, just reach a very good level of music at home.

Before having a 100% fixed idea on the compression model, I would like to understand the digital path.
Do you know good articles / threads where the digital chain is exposed, i.e. the amp / dsp / filter possibilites?
I want to make the digital progression step by step, I will not copy harman crown.

[Mitchco]

If you are into computer audio playback, one can perform all of the DSP in the software domain. Here is one example from a member that chose this route for his M2's and subs: https://audiosciencereview.com/forum/index.php?threads/jbl-m2-audiolense-digital-crossovers-w-subs.2369/

I did something similar with JBL 4722's: https://www.computeraudiophile.com/ca/ca-academy/%C2%A0integrating-subwoofers-with-stereo-mains-using-audiolense-r712/ Mentioned to say I am very impressed with the 4" 2453h-SL CD"s that replaced the 2432's. The 4" SL's can make it almost to 20 kHz, as shown in the measured frequency response in the article. Sounds really smooth to my ears with really low distortion...

User notnyt on the AVSForum measured numerous 1.5" JBL CD's including the D2430, on the 2384 waveguide: https://www.avsforum.com/forum/89-speakers/1925586-just-purchased-pair-jbl-4722n-speakers-121.html While not the M2 waveguide, maybe give you some ideas... The measurements go on for some 40 pages, including notnyt's CD preference..

Good luck with your journey!

[sebackman]

Hi Rodec,

Sorry for a lengthy post.

This will lack some spaces between words and I don’t know why that is but is a result of being cut and past from Word.

It’s really that simple. If you want audio Nirvana (for some) build faithful M2 clones/system as they are (to me and many others) a superior design and performance. -And they can be adapted by the DSP to the room they are put in.

They are probably the only such advanced speaker system in the world right now that it is possible to replicate in close enough detail to expect very close to original results.

As member 4313b elegantly put it while back: “Either you like them or you are wrong”. 😊

You also do have member POS in Paris and he is very experienced and give very good input o M2 and many other things.

Having said all that, many of us enjoy other combinations, even on M2 WG’s. So, it is really your choice 😊 as undoubtedly there is little chance that someone else has tried your eventually chosen combination of drivers in combination with your electronics. Hence, we don’t know and can only provide help and experience in parts not the whole. With M2 clones using the original parts/electronics we can be pretty sure about the expected outcome.

I myself have chosen the second path in building my own combinations and had excellent help from very experienced members here on LH and elsewhere, but for “system” design I had to do the hours at the measuring rig and listening using reference material and reference speakers to keep the findings reasonable sane. Fun but time consuming.

Regarding the digital chain there is really a matter of what your source of material is. Is it a digital source, then keep it in the digital domain for as long as possible. To go further on this topic, we venture into mined territory as there are many views on this. I will just share my view and others can correct and/or share their views.

DAC’s are rather easy to get right, there are only a handful manufacturers of chips and they all provide standard circuits to use. Many high-end producers may alter the schematics but since you are working with rather controlled environment and digital input to the circuits my findings are that the most important areas are the clock and the output filters.

Low sampling rates require more expensive filters components and many argue that high sampling rate or up-sampling improves quality of which I’m not so sure. Please see attached articles. Most producers go high sampling because it is easier and cheaper and many others do it because the general view is that “higher is better”.

The real problem IMHO is the sample rate conversion done in most digital equipment to manage clock drift. In a studio you typically would see all “machines” run 24 bit / 96Khz from one master clock. No sample rate converters in the chain.

The CD format is 16bit / 44,1kHz (red book) format so there has to be a conversion before the material leaves the studio chain where it normally is 24/96. As 44,1 and 48kHz is nor evenly divided such conversion is power consuming to be done bit perfect, hence this procedure is often done off-line when leaving mastering. The reverse is also true going from 44,1 to 48/96/whatever-times-8 is also difficult on the fly, hence the inherent problem in sample rate converters. Even so-called high quality femto clock’s drift, hence most equipment with their own clocks use sample rate converters on the input circuits to re-clock the material. In the BSS world you can actually disengage the sample rate converters in SW but unless you use the same clock unit for both sender and receiver unit it does give audible digital artefacts.

However, my view is that most DAC implementations are “good enough” and often what many people refer to as identifiable sonic differences is really differences in sound pressure level. The ear is not really that sensitive in frequency shifts but very sensitive to sound pressure changes. I’m not saying that they all sound alike but I’m claiming that in a full double-blind AB test of high-quality equipment and with Lab Standard calibrated sound pressure levels, very few would be able to identify the differences. The Nyquist theorem still rules.

The real problem lies on the other side, the ADC. Thera are many ways to convert analogue to digital and the circuits are very sensitive on the analogue side. Combined with the fact that most of us does rarely listen to the systems at full power the ADC will have very low level of input signal to work with and often come close to the signal to noise floor. Her I would argue that the difference is rather noticeable between different units, even at the same sound pressure level. Any thermal noise, jitter or digital artefacts here would be audible well after the DAC’s.

And for computer music my short recommendation is to use an external sound card with asynchronous USB connection. Simplified, in a synchronous USB link the computer sends data when it wants and in an asynchronous USB link the sound card demands data in the pace it can buffer it. This is regardless if you use analogue or digital out from the sound card. And the best is to use an external sound card that uses the clock signal of subsequent the DSP/XO to avoid sample rate converters further down if you keep the signal in the digital domain. Unless you go studio style with a separate clock unit BSS is the only manufacturer (that I know of) offering an sound card with asynchronous USB running the clock from the DSP and they achieve that trough their proprietary BLU-Link connection. The BLU-USB is connected to the computer asynchronous and then feed the signal in digital form 24/48 to any BSS BLU-Link enabled unit. Not known to very many but cheap, reliable and good sound quality if you run BSS DSP.

Fore my own part I have tried to solve this by keeping the signal in the digital domain as long as possible running an all-digital system using a Meridian G68 only as a “digital switch”. The Meridian also has a Dolby decoder so it can provide 7.2 SPDIF digital 24/48 or 24/96 out. I then feed a BSS BLU-800 DSP equipped with digital input cards from the Meridian. From the BSS I have 16 channels analogue out to feed the power amps. To control the volume, I have two 8-channel attenuators (Burr Brown VCA) between the output of the BSS DSP and the power amps. In reality the digital attenuator in the BSS would be good alternative as they internally work with 41 bits floating point and hence you can reduce volume in the digital domain without losing resolution. If you drop volume on a 16-bit signal that would mean that you lose resolution. And you can control the BSS from the iPad or the iPhone via the app.

But there are many good alternatives here besides BSS. From my point BSS is a bit pricey but the are very flexible and the algorithms do sound better than most other units I have had the chance to test. The HW probably does not deviate too much from others but the SW is very good IMHO.

I realize now that I can go on forever on this topic so I shall stop here. I did attach an article from Xiph.org that is close to my own beleives, however I do accept that there are many other very relevant views on this and this is only my 25 cents.

I do believe that many voices in our beloved hobby, be it producers or others, tend to be driven by money reasons rather than the laws of physics. There is much money to be had in supporting different trends regardless of real-world results. The HiFi business has to a large extend taken the form of the fashion industry and you cannot argue about taste.

I have attached a link to a speech from Floyd Toole at CIRMMT that has many good points. Well spent time.https://www.youtube.com/watch?v=zrpUDuUtxPM


Here is also some interesting reading from Mr Toole in 2015.
http://www.aes.org/e-lib/browse.cfm?elib=17839

And I have also attached some interesting documents.

Sorry for the rant.

Kind regards
//Rob

[herve M]

Hello Rob,
I can not send you new private message::crying:
"


Sebackman has exceeded their stored private messages quota and cannot accept further messages until they clear some space."

Regards
Herve:)

[sebackman]

Hi Herve

Sorry for that. Didn't know it was full.

Now cleaned. :thmbsup: .

//Rob

[rodec]

Hi Mitcho, I am not in music business and I do not play guitar like you. I will add Acourate in the list of candidates. I though the M2 would be perfect w/o subs. And a lot of good reading via the links you posted, even if there are very technical for my starter level.
>Good luck with your journey!
Will be long. Thanks.

Hi Sebackman, first, I love the first part of the Floyd utube video (I did not finalized yet).

>You also do have member POS in Paris and he is very experienced and give very good input o M2 and many other things.
I need to progress on some areas before talking with him ;-)

>Regarding the digital chain
I am learning what could be the global scheme of the system, I spent few hours this week end just to read and read again. I start on a specific forum, and I jump from threads to thread, sites to sites, new areas to look into.
I saw BSS, minidSP and I’ll check how to use room correction.
All, you help a lot, I takes me a lot of time to read all you’ve sent.

Those M2 are very interesting and very exciting

[rodec]

Took me some weeks to come back. Sometime life is busy ;-)

The thread title shall change from now on. Indeed, reading your feedback and ones from various M2 threads versus it is my first attempt with compression and simulation tool, I will follow the classic path and I ordered the standard M2 speakers.
While seeking the ports' dimensions which are not clear from the various post, selling old stuff to fund M2 parts (what K$ it is ), I also look at the active cros over, BLU and .

On the digital side, I would like to reuse a Cambridge Dacmagic (if you think acceptable), and then I miss the active crossover (miniDSPlike) and the bass poweramp. Perhaps I will use a tube amp for the compression, if I succeed to manage the gain with the amp of the bass (hypex like).

Also do you know the main differences between BLU 800 and blu 3xx or blu 100?
Thanks.

[Palmgren]

sebackman is writing about using the M2 WG as they are easy to come buy. I have thought that the M2 driver and WG are hard to find. Has this changed or are you so well connected that you have a backdoor to the kitchen at JBL?

[Mr. Widget]

https://reconingspeakers.com/?s=M2&post_type=product

Scroll down a bit. They have numerous M2 parts.


Widget

[rodec]

yes, ask a quote at Reco and wait a bit jbl to deliver parts to Reco. But you right I read somewhere on forum that guys in the JBL business can order spare parts (or/and if you know one).

[rodec]

Hi all,

First, I would like to rename this thread by: yet another M2 clone, ... Indeed, I decided to use the standard M2 configuration. Do you know how to rename the title?

Based on your input, sebackman, ivica, Mitcho, Flyod indirectly, DonC 's M2 proposal, and Thomas who helped me a lot, I succeeded to finalize one M2 clone proto!
After some training on utube, I configured the bss blu160 (analog card for the time being) and use Pos' amps for test because mine was to small (100W).
The cabinet is similar to the original ones without using CNC, so it took me one week end to make guides for the router. I've learned to be patient there.
So, similar to M2, 3D priting ports, without absorbant inside (yet), BUT with small holes I think everywhere as I did not cut perfectly.

It has been very exciting to hear the M2 the first time, wouah. I do not use measures, just folks who hear and ciritic.

PS: for info, Pos' ones sound pretty good, "aux petits oignons" as frenches say ;-)

During the tests, I've found two tracks worth to be listened to -enjoy-
- Maria Mena, I was made for loving you ; https://open.spotify.com/track/7guh9tEA8xKPWX9NLEK1k0
- fading sun, terje lsungset ; https://open.spotify.com/track/4KRTc3Gp9LLfMktZ7Xe7U1
The second one sounds basic on basic speakers (my computer config), but just try them on the M2s ;-)

Next steps are a) moving from proto to real, b) and selecting the amps (as my DiY tube amps are not perfect currently)

Thank you for your inspiration, sounds good ;-).

[Champster]

I am not a regular reader of the forum but jumped in today to find your thread. I offer you the highest level of encouragement to build a pair of M2s! I bought a pair with the 4-1250N (4x1250WPC) Crown Amp last year and couldn't be happier! I love this system and will likely never change! While you're at it, remember, any deviation from JBLs design and it is no longer an M2. The magic of this system is multifold. First the drivers are unlike anything ever developed by JBL or any other manufacturer that I'm aware of. I've had so many other high end speakers in the last 30 years that I forget most of them. The M2s are truly incredible. These woofers have incredibly quick response to transients and the compression driver is more like a super powerful electrostatic driver with the accuracy and delicacy you've heard from electrostatics but with a tremendous amount of head room. I have never heard even the slightest sense of strain or stress at even the very loudest of playback levels. Importantly, the system is just as revealing (but not as much fun) at very low input levels. I think I underestimated the need for a high powered amp when I bought these but now that I have them and better understand the design of redundant drivers, it makes sense that JBL recommends this much power. You'll want a lot of amplifier headroom to match the capability of these drivers. And OH the waveguide….. It is magical! They image like crazy!!!!

The tracks you suggested are fantastic! I'm halfway through the first album on Tidal… Great suggestions and good luck with your build. Stick to JBL's design and you won'd ever change speakers again...

[rodec]

I am not a regular reader of the forum but jumped in today to find your thread. I offer you the highest level of encouragement to build a pair of M2s! I bought a pair with the 4-1250N (4x1250WPC) Crown Amp last year and couldn't be happier! I love this system and will likely never change! While you're at it, remember, any deviation from JBLs design and it is no longer an M2. The magic of this system is multifold. First the drivers are unlike anything ever developed by JBL or any other manufacturer that I'm aware of. I've had so many other high end speakers in the last 30 years that I forget most of them. The M2s are truly incredible. These woofers have incredibly quick response to transients and the compression driver is more like a super powerful electrostatic driver with the accuracy and delicacy you've heard from electrostatics but with a tremendous amount of head room. I have never heard even the slightest sense of strain or stress at even the very loudest of playback levels. Importantly, the system is just as revealing (but not as much fun) at very low input levels. I think I underestimated the need for a high powered amp when I bought these but now that I have them and better understand the design of redundant drivers, it makes sense that JBL recommends this much power. You'll want a lot of amplifier headroom to match the capability of these drivers. And OH the waveguide….. It is magical! They image like crazy!!!!

The tracks you suggested are fantastic! I'm halfway through the first album on Tidal… Great suggestions and good luck with your build. Stick to JBL's design and you won'd ever change speakers again...


Thanks for your feedback, very interesting and confirming some first impressions I had.

yes and yes, you describe pretty well what I am feeling actually.
I used a classD amp >500W and indeed it makes the difference, just WOUAH. Really amazing impression, stable, you push and drivers seem not to be limited, the music envolps you, and details are present even in another room. The first day after the proto ending, I came back from my work sooner just to listen more tracks... ;-).
I remarked a impressive basic low quality if I use a low quality DAC. With a medium DAC quality (not professional), it becomes immedialty very good. So amp, DAC will be key.

I will receive soon a micr, then REW will judge the wood prototype realisation quality better than my ears. I will see how far I am to a M2. I will need the forum to explain me what I will see from REW.

and good music experience sharing Champster, nice.

[rodec]

First use of REW.
I assume the down pics 150-300 Hz, 2, 2.5 and 4k highlight stuff to correct, so I will welcome your feedback.
Note there is no absorbant in the cabinet.

micro was more or less 1m at the bottom of the horn, test outdoor (but the speaker was still inside the house), single speaker.
config is : PC -> DAC -> BSS -> amps -> micro.
I made two measures, PC volume at 10 and at 40, see below.

volume @10
83714

volume @40
83715

[Champster]

I'd like to see the curves when the speaker is placed outside with no reflection barriers anywhere close to the speaker.

[rodec]

I'd like to see the curves when the speaker is placed outside with no reflection barriers anywhere close to the speaker.

Thanks champster, I see, will do tomorrow, start to be night overhere.

I struggle with the micro position, should it be placed at the middle of the cabinet or more in the middle of the compression?


By curiosity to see how a room influences the response, I made a mesure in a small room 15sqm (plus upgraded to REW 5.20 beta 8), with or w/o curtains, just incredible. Below is with curtain (1/48 smoothing):
83791

and the beast
83792

[rodec]

I'd like to see the curves when the speaker is placed outside with no reflection barriers anywhere close to the speaker.

OK, I placed it accordingly to the length of cables, not totaly in the middle of nowhere:
83810

83811

83814

83813

[Champster]

Excellent work! That has all the makings of looking just like a production version.

I would think you’d want to orient the Mic in the middle between the two drivers. To have it on axis with the horn makes the off axis response of the woofer less than idea as the frequency rises toward the crossover point of 800. This may be part of the reason you’re seeing uneven response from the woofer, but wow the horn’s response is very flat.

And just to make sure, are there any reflective barriers (walls or fences) in front of the speaker as it sits in the photo?

[rodec]

Excellent work! That has all the makings of looking just like a production version.

I would think you’d want to orient the Mic in the middle between the two drivers. To have it on axis with the horn makes the off axis response of the woofer less than idea as the frequency rises toward the crossover point of 800. This may be part of the reason you’re seeing uneven response from the woofer, but wow the horn’s response is very flat.

And just to make sure, are there any reflective barriers (walls or fences) in front of the speaker as it sits in the photo?


Hi Champster,

good it sounds good ;-), promising. Currently, I did not put any absorbent inside the cabinet. Do you think it may change something?

For woofer response, yes a fair explanation. I will redo a measure with the micro placed between the two speakers. Just a vocabulary question, when you say "orient", do you mean just "tilt" or reduce the height by 20cm down?

Yes there is a fence screwed on top of the woofer to preserve it form many hands. I will remove it for the next measures?

Thanks,

[Champster]

Hi Champster,

good it sounds good ;-), promising. Currently, I did not put any absorbent inside the cabinet. Do you think it may change something?

For woofer response, yes a fair explanation. I will redo a measure with the micro placed between the two speakers. Just a vocabulary question, when you say "orient", do you mean just "tilt" or reduce the height by 20cm down?

Yes there is a fence screwed on top of the woofer to preserve it form many hands. I will remove it for the next measures?

Thanks,

Yes, 1” thick, fiberglass on all surfaces will improve the response a lot.

Orient just means “to place”. I would just lower the microphone so that it is at the height of the lowest part of the waveguide or to say it another way, where the waveguide and the woofer meet.

The wire screen over the woofer won’t effect the response but if you have a building or another structure that reflects sound back toward the speaker and microphone, it will produce unreliable frequency measurements.

Nice work!

[sguttag]

1" fiberglass but none on the board with the drivers. (5-sides). If you search the other M2 DYI thread there are pictures showing how various people have lined it (as well as a genuine M2).

[rodec]

1" fiberglass but none on the board with the drivers. (5-sides). If you search the other M2 DYI thread there are pictures showing how various people have lined it (as well as a genuine M2).

Then, I deducted from somes posts and on kw55 video, seems a 1" fiberglass every where except
- on the front panel from top to bottom
- on the horizontal "low separator" between medium speaker area and ports area

your feedback?

[dn92]

Hou can use Soniroll fiberglass, same as the one pos used that has similar density as the one used by JBL.
I got it from Point P shop where you can order it.

[rodec]

Hou can use Soniroll fiberglass, same as the one pos used that has similar density as the one used by JBL.
I got it from Point P shop where you can order it.

Yes, a good choice, but I did not succeeded to find any stock around Paris. Perhaps I can buy an old stock of a Diyer which did not used all his roll ;-)

So I bought specific sound absorbant to make a test as from this WE:
83917

And, I am doubtfully with the measures.
a) I would have expected more changes with and w/o damping
b)- 90Hz to 300Hz a bit too lower compared to the range 700-10k

For M2's owner, do you have a similar result?


83918
without damping

83919
with Damping

[rodec]

GREAT step today! Following lesview suggestion, took a variation of the BSS 160 config proposed by notnyt on AVS forum.
Even with one speaker, the sound is so great, it turns all day long. Placed in the garden, I will soon organise a concert ;-)
I can't imagine when two will be ready!

YES, a step because the M2 prototype sounds less agressive, more homogenous, despite some work still to be made as you will see.

The measures are made in the garden, 1m, DO NOT look too much of the DB scale as I did not use the same volume on the PC.
Two measures,
- green : orginal file from JBL site for BSS80
- purple: notnyt's config from https://www.avsforum.com/forum/89-speakers/1724906-jbl-705i-708i-7-series-master-reference-monitors-725g-728g-subwoofers-jan-2015-a-93.html#post57945990

Actually, more flat, but still have this hole between 80 and 250. I assume it should be flat, don't I?
Could it come from a bad woodworking on the cabinet like some holes between two wood boards

84127