Horn/Driver Comparisons

[Mr. Widget]

We're pretty conscientious about keeping related material in the same thread here.

See post #68 et.seq.

Yeah, sorta, sometimes... I was too lazy to start digging.

Thanks Zilch.


Widget

[Guido]

We're pretty conscientious about keeping related material in the same thread here.

See post #68 et.seq.

OK, sometimes I'm blind but not so blind. I mean distortion measurements. The 2435HPL first had quiet high distortion. Was it measured again after refurbishing?

[Zilch]

No, sorry.

I'll put it on the list for CLIO testing here....

Did you read the Geddes article on distortion in the latest AES Journal?

[Guido]

Did you read the Geddes article on distortion in the latest AES Journal?

I overread this. Do you have it? You still have my mail addy, yes?

[Steve Gonzales]

An older thread with a weath of good information!!! I hope some of the newer members will take a look at this thread. This definately sheds light on what an engineer must figure out before going into production. For the members that are already up to speed on this stuff, I can understand a bit better now, how a novice might look like when he stuffs a horn/driver into an unintended enclosure. We're all after the same thing, it's just a steeper learning curve. Armed with this quality information, not so steep now.

[mbask]

Oh...good they're gone

[Too Tall clist]

Here is a plot of Zilch's "better" 2435HPL. We are not sure what the specs are for distortion, but this unit has significantly more third harmonic distortion than the 435Be.

Hi,
I just started working on a passive xover with a 2435HPL.
I can’t give you any useful measurements right now because the 1.5” throat driver was mounted on a 2” throat horn. So right now someone is looking for some 1.5” throat horns that will fit in the cabinet.

I did have some question pertaining to the driver itself.
I have heard some outrageous quotes for what the driver will sell for.
If you go here you will see a retail replacement cost of the diaphragm (I presume) of $756.00

http://www.jblproservice.com/pdf/Tra...rts%20List.pdf

All this because of the use of Beryllium.

Note on the same spreadsheet the 2431 diaphragm retails at $138.00.

I have seen several 2435HPL on ebay for around $240 each.
About 1/3rd the cost of its diaphragm?

So I wanted to know if there were after-market diaphragms made from something less expensive like aluminum? And that is why they were going so cheap on ebay?

Considering the cost of the diaphragm it would seem fool hardy to use these for anything less lucrative then corporate gigs or something else that pays as well.
Frying one in a 150 seat night club in the middle of a 80s rock tune might cause you to be clinically depressed.
The Talking Heads are important, but not THAT important.

I decided to attach a picture (If I can figure out how…). Note again it is mounted on a 2” throat Selenium HMA4750-SLF 90x40 horn.
No throat adapter was used, which is why the high frequencies above 6.7kHz are obliterated.

The frequency response below that should be valid.

For measurement background-
Measurement program is Praxis with a Praxis mic.
The horn was dropped into a wastebasket to point it straight up and a mic 1 meter above the mouth pointing down. So there was no baffle, just the horn itself.
The IR was gated at about 10ms to remove the ceiling bounce. The window was about 7ms long (I think).

If you look at the top of the plot it says 9.03dB offset.
Praxis measures referenced to 1-volt. To find 1-watt 2.83V into 8ohm you add 9.03dB
And this is an 8-ohm nominal driver with everything in its useful range at 6ohms (except for resonant peaks.)

So the frequency SPL is correct for the horn used.

If I figure it out I will post the z plot too.

I hope someone can help me out with the after-market diaphragm question.
Thanks.

[Zilch]

http://audioheritage.org/vbulletin/s...ad.php?t=14357

[Robh3606]

So I wanted to know if there were after-market diaphragms made from something less expensive like aluminum? And that is why they were going so cheap on ebay?

No aftermarkets are available that I know. The drivers on Ebay are the real deal. Some need the gaps cleaned but other than that they are a real bargain. You can run a 2431 aluminum in a 2435 core and visa versa. They are the same driver asside from the diaphram material.

Rob

[Mr. Widget]

No aftermarkets are available that I know... You can run a 2431 aluminum in a 2435 core and visa versa. They are the same driver asside from the diaphram material.

Yep... but there is a reason for that expensive beryllium. Performance.

I have no idea if you will be able to appreciate the difference in a club setting, but there is no comparison between them in a studio monitor or high end home system.

You might want to buy a pair of the $138 aluminum diaphragms and see if they satisfy your needs.


Widget

[Too Tall clist]

Yep... but there is a reason for that expensive beryllium. Performance.

I have no idea if you will be able to appreciate the difference in a club setting, but there is no comparison between them in a studio monitor or high end home system.

You might want to buy a pair of the $138 aluminum diaphragms and see if they satisfy your needs.


Widget

Hi and Thanks.

These aren’t for me. I’m just designing the xover.
I do appreciate the performance issues, but I don’t want my customer to get in over his head either.

For example if the 2435 drivers he has have aluminum diaphragms in them if he destroys one he might be able to afford the replacement.
If they are the expensive spread I want him to know what it’s going to cost him BEFORE I design a xover for him. I don’t know if my design will work with both diaphragms till it’s done.

Also at the price point on ebay I would not be surprised if they are 2431 diaphragms.

What is the best way to determine which diaphragm is in there?

So, have we decided how low a 4th order xover is safe for these?


[edgewound]

I got my (4) 2435's from a guy on eBay as well. I haven't looked at the most recent auctions, but he is a guy in Hesperia, CA.

He delivered mine to my shop. Very nice guy. He said they came from Vertec systems from a huge nightclub operation that went out of business.

I havent had the occasion to replace any diaphragms yet on 2431 or 2435 but I have opened mine to look at the dia's, and yes, they are Be.

I'm not so sure they are a drop-in interchange without modifying the mounting ring.

It would make more sense to just buy 2431 driver's outright, if the cost is an issue....which for most people it would be.

The Ferrofluid has dual purposes: (1) wick away heat from the voice coil to the top-plate (2) Dampen the moving mass for less distortion....but at the expense of minimal sensitivity loss.

[edgewound]

So, have we decided how low a 4th order xover is safe for these?


Seems to me that passive for 2435 is too high risk in a live situation. I'd think that active digital with brick wall filters and comp/limiting would be the best bet.

[Too Tall clist]

Seems to me that passive for 2435 is too high risk in a live situation. I'd think that active digital with brick wall filters and comp/limiting would be the best bet.

I don't see the risk.
If the design is correct the passive filer should work as well as the digital. If you are going to push the speaker to the edge the DBX 160 is in the first rack 2 spaces down below the Varicurve.

As for your brick wall filter if I move the xover up just a little bit there is little difference.

One thing is for sure. On the financial front, if you can afford those drivers you should be able to afford a Lake DSP for a system controller.

And I still would like to know what is recommended for a 4th order high pass, because despite the fact that a DSP is better or not these are going in 2-way passive with a 12" cone because that is what he owns.
Thanks

[Zilch]

Look to the JBL products using 2431 to choose a waveguide, AE series, typically. Crossover guidance is there for each.

Other options, 2381, 235x horns.

Can't do the crossover without knowing and measuring on the horn/waveguide to be used....