MoD is playing with the Lansing heritage :-)

[toddalin]

@ Earl K

Thank You.
Jes, i should buy 077/2405 diaphragms.

Not that easy. The diaphragms differ in architecture and an 077 may touch the phase plug of the 075. When I made this change, for testing purposes, I made shims to go between the phase plugs and diaphragms to correct this potential faux pas.

BTW, this is the spectrum for a stock 075 with an original diaphragm.

https://youtu.be/pbbS0QYK2_o

https://youtu.be/zicT8bw1ZmM

[1audiohack]

Hi Barry,

I'm sorry my too quick post has caused you an inconvenience. It was not the intent. Will do differently next time. Regards,

Richard

Hello Richard!

No inconvenience at all, none whatsoever. I just didn’t have a complimentary reply.

I hope you and yours are well!

My best.

Barry.

[RMC]

Hi Barry,

Thanks for the reply. We're all doing ok, hopefully your family too. Winter is slowly fading away here though still -10 C some nights...

We're not virus sick so that's good news nowadays when you have a look at TV. Doing income tax returns these days for family members. Got about a month of that. Not my dream work, gets a little more complicated every time, but somebody has to do it, and I'm unanimouly de-sig-na-ted for the yearly task. If I get some money back from the tax man when doing mine last, then it might go towards something audio, my reward...

The New year's or so gift I gave to myself is still stashed under a table in basement living room, haven't had time to play with it, wife hasn't noticed it yet! maybe better this way.

Btw I'll send you a PM for something else. Regards,

Richard

[MoD]

After a while I am back.
@ RMC, 1audiohack, thank You for input about La Scalla and 075.

I have ditched idea about La Scalla, it is too short horn to expect bass output i desire. I am thinking about reconstructing MoD Imperial in front loaded horn, once in the future.

I have allso spent some time analysing my 075 problem.
I have come to conclusion that inside my 075 are some chinese diaphragms which only look ok (from distance ) and that explain measurement i have on them on second page of this topic...

Time for new diaphragms...
Which one would You recommend?

I am in doubght on these, those are for 077 and I would have to make shims for phase plugs...

https://reconingspeakers.com/product/jbl-2405-aftermarket-diaphragm-16-ohm/



They look ok, but...

[ivica]

After a while I am back.
.....
I have allso spent some time analysing my 075 problem.
I have come to conclusion that inside my 075 are some chinese diaphragms which only look ok (from distance ) and that explain measurement i have on them on second page of this topic...

Time for new diaphragms...
Which one would You recommend?

I am in doubght on these, those are for 077 and I would have to make shims for phase plugs...

https://reconingspeakers.com/product/jbl-2405-aftermarket-diaphragm-16-ohm/

They look ok, but...

Hi MoD,

I have bad experience with 'aftermarket 2405' diaphragms, I would not suggest You to waist your money.

Regards
ivica

[MoD]

I agree, original is original.

But...


K130 which start my story with JBL came to me in a trade (read: cheap). They went to storage and i went to internet. I liked what I read/hear. Ok, not all. Price wise idea was way above my range. So they sat on shelve for few years. Until, one day I said to myself; screw magnet recharging, screw original recone kit. No risk no profit, so I bought recone kit for D130 from Sound speaker repair, kits arrived, they looked good. As aviators used to say: If it look ok, it is ok. So they were reconed.

I do not think that my speakers sound the same as they would sound with recharged magnet and original recone kit. That said, i should say that i have never heard good original D 130. I have learned from this and other forums, asking people who had experience, listening D 130 on you tube (yeah, I know ) about sound which is to be expected from D 130, and I have build mental "picture" of how they should work. And they fulfilled my expectations.

My conclusion is that for some models there are aftermarcet recone kit which for money gets big procentage of original sound.
I forgot to look at Sound speaker repair for 075 diaphragms when I wrote post about diphragms , but it looks that they are spending some effort to get a decent replacement par, and because of good experience with D130 recone kits, I think that I should risk hundred dollars for a pair of these:


http://www.soundspeakerrepair.com/mm...y_Code=DIA-JBL


It is going to make my 075 franken tweeters but all I need is good performance from 6000 Hz to 16000 Hz. No guts no glory :-)

[ivica]

I agree, original is original.

But...


It is going to make my 075 franken tweeters but all I need is good performance from 6000 Hz to 16000 Hz. No guts no glory :-)

Hi MoD,

I would suggest You may be Beyma CP21 or CP22 instead of "aftermarket JBL 2405/02 diaphragm"

https://usspeaker.com/beyma%20CP21F-1.htm


regards
ivica

[MoD]

Wow!

I did not know that Beyma is producing knock off JBL drivers. They are more than double expensive than Sound speaker repair diaphragms, and due to covid caused recession i will think twice before purchasing anything for audio hobby. It would be great to bring that 075 in some kind of useful working order for minimum money.

But both cp 21 and cp 25 are very interesting to me, and one day...

I have also came around this topic:

http://www.audioheritage.org/vbullet...or+comparisons

and I am in the middle of revision my 075 now, when I finish I will post results.

[ivica]

Wow!

I did not know that Beyma is producing knock off JBL drivers. They are more than double expensive than Sound speaker repair diaphragms, and due to covid caused recession i will think twice before purchasing anything for audio hobby. It would be great to bring that 075 in some kind of useful working order for minimum money.

But both cp 21 and cp 25 are very interesting to me, and one day...


and I am in the middle of revision my 075 now, when I finish I will post results.

Hi MoD,

http://www.audioheritage.org/vbullet...l=1#post299484

regards
ivica

[MoD]

Hi Ivica,

Wow, 5 dB less on Beyma. It also has a "bump" in response between 7 and 10 kHz. That could produce a lot of sibilance i think. At the end a lot better than my 075 with those wrong diaphragms.

And, speaking of diaphragms...

I have dismantle my 075.
At the end I don`t know what they should be, but I have noticed that central ring do not lay firmly on the pole piece. I have remembered Simply speakers video about installing 077 diaphragms in to 075 and I went through this topic;

http://www.audioheritage.org/vbullet...or+comparisons

So I made 0,19 mm thick rings to put below diaphragm central ring. That made difference. And I have measured;



But, when I have install tweeters in the system, although, they performed closer to what they should, they had a lot of sibilance. And I mean a lot. Sssss`s were cutting ears. Measured system;



It was obvious that around 7 KHz and past 10 kHz there are big resonant or distortion or breakup peaks. I managed to tame those peaks by apply heavy eq on dsp. That tamed peaks but bring another set of problems, sound is not right...

I have also found those diaphragms, they should be original;

https://www.simplyspeakers.com/jbl-r...gm-d8r075.html

What do you think?

[robertg]

Those diaphragms are discontinued.

[Ian Mackenzie]

http://www.troelsgravesen.dk/Beyma-CP21-F.htm

[MoD]

So, at the and I have bought cheap chinese diaphragms for 075. 15 dollars for four. They are rubbish, but work better than old ones. So Beyma is in plans in the future.
In the meantime, one stupid question. Let say i have adapters which enable for 1" compression driver be mounted on horn for 2" drivers.
How stupid would be to take 2360 horns and marry them with 2426 driver? I will probably try, but it does not hurt to ask...

[ivica]

So, at the and I have bought cheap chinese diaphragms for 075. 15 dollars for four. They are rubbish, but work better than old ones. So Beyma is in plans in the future.
In the meantime, one stupid question. Let say i have adapters which enable for 1" compression driver be mounted on horn for 2" drivers.
How stupid would be to take 2360 horns and marry them with 2426 driver? I will probably try, but it does not hurt to ask...

Hi Mod,

if the mentioned 1" to 2" adapter is of proper length, I would not expect any problem that 2426 to be used with the mentioned 2360 horn.
As an example You can compare 2307 and 2311 horns. The first one is 1" horn while the second one is 2". Each of them were used over, say, 1200Hz, with 2308 lenses. The first one can be find in 4343/44/45 monitors, while the second one can be find in 4350/55 monitors.
On my personal opinion I would prefer 2311 & 2308 then 2307 & 2308.

regards
ivica

[ivica]

Hi Ivica,

Wow, 5 dB less on Beyma. It also has a "bump" in response between 7 and 10 kHz. That could produce a lot of sibilance i think. At the end a lot better than my 075 with those wrong diaphragms.

And, speaking of diaphragms...

I have dismantle my 075.
At the end I don`t know what they should be, but I have noticed that central ring do not lay firmly on the pole piece. I have remembered Simply speakers video about installing 077 diaphragms in to 075 and I went through this topic;

http://www.audioheritage.org/vbullet...or+comparisons

So I made 0,19 mm thick rings to put below diaphragm central ring. That made difference. And I have measured;



But, when I have install tweeters in the system, although, they performed closer to what they should, they had a lot of sibilance. And I mean a lot. Sssss`s were cutting ears. Measured system;

It was obvious that around 7 KHz and past 10 kHz there are big resonant or distortion or breakup peaks. I managed to tame those peaks by apply heavy eq on dsp. That tamed peaks but bring another set of problems, sound is not right...

I have also found those diaphragms, they should be original;

https://www.simplyspeakers.com/jbl-r...gm-d8r075.html

What do you think?

Hi MoD,

Using hi-pass crossover for UHF driver (JBL 075) You can easily remove the influence of the mentioned "hill" in the driver FR round 4kHz ~ 10kHz, especially if 3rd or 4th order Hi-pass would be applied, or a kind of band-stop width about 6kHzm Q=1.

regards
ivica