Which horns for JBL 2451 Be drivers?

[sebackman]

I would definitely look at a modern wave guide before going the diffraction slot horn-way. To me the M2, 4367 and even the el-cheapo VTX-F12 WG does sound better than many expensive horns with a diffraction slot.

It is a surprisingly small difference between the el-cheapo plastic JBL#506815 and M2 WG and in my world smaller than between the new generation WG’s in general compared to the older horns. Maybe that is just me.

Since the #506815 WG is so cheap I would at least give them a try before venture into more exotic (expensive) horns. The fact that is cheap, small, uggly and made in plastic does not change the fact that they sound and measure good.

Regarding 2450SL vs 2451 core I have always thought that they are identical. They are, as far as I can figure out, not. The phase plug is different and sits differently in the 2450SL. After having moved dia’s (Ti, SL, Be) around between them I have also come to the conclusion that they do measure and sound different. Differences are small but given a choice I would opt for 2451 core.

With a proper SL diaphragm (preferably D8R475Nd or D16R2451SL) they measure and sound wonderful on the waveguides mentioned above.

Be's are also fine, but as stated above, do benefit from an UHF unit as in all JBL K2 speakers.

My 25 cents.
//Rob

[engineerjoe]

I would definitely look at a modern wave guide before going the diffraction slot horn-way. To me the M2, 4367 and even the el-cheapo VTX-F12 WG does sound better than many expensive horns with a diffraction slot.

It is a surprisingly small difference between the el-cheapo plastic JBL#506815 and M2 WG and in my world smaller than between the new generation WG’s in general compared to the older horns. Maybe that is just me.

Since the #506815 WG is so cheap I would at least give them a try before venture into more exotic (expensive) horns. The fact that is cheap, small, uggly and made in plastic does not change the fact that they sound and measure good.

Regarding 2450SL vs 2451 core I have always thought that they are identical. They are, as far as I can figure out, not. The phase plug is different and sits differently in the 2450SL. After having moved dia’s (Ti, SL, Be) around between them I have also come to the conclusion that they do measure and sound different. Differences are small but given a choice I would opt for 2451 core.

With a proper SL diaphragm (preferably D8R475Nd or D16R2451SL) they measure and sound wonderful on the waveguides mentioned above.

Be's are also fine, but as stated above, do benefit from an UHF unit as in all JBL K2 speakers.

My 25 cents.
//Rob

Do you mean the 5006815? like this?
http://www.prosoundservice.com/m9/JBL%20Pro%20Parts%205006815--jbl-pro-parts-5006815-horn-90-x-50.html
or
https://reconingspeakers.com/product/jbl-horn-lens-5006815-stx825/

[sebackman]

Yes, that is the one.

Emotionally they are generally ruled out day one, due to looks and material, compared to other much more impressing packages.

But in reality, they perform very well with the 4" 2450SL/2451 cores. JBL uses them in their +$3k VTX F12 /F15 speakers together with D2 drivers.

I use them in several systems and today. My HT uses them with 2451Be’s and 045’s UHF on top.

-Even made a VTX F12 clone with 2206 woofers and 2451SL’s in these WG’s and they work just perfect.

The M2 WG is a step up no doubt, but bigger and more expensive. However, the step up is smaller than the eye would like us to believe. Only your ears and wallet can decide if it is worth it.

One must bear in mind that M2 is not a bunch of drivers it is an integrated system. If you take away or change a compenent it willl look the same but it's not an M2 system anymore.

I have both and enjoy them both. Where size and money matters the #5006815 can be an interesting choice. In an all-out high end alternative I would build an full and faithful M2 clone, unless you are willing to spend much time to measure and develop your own tunings with an alternative choice of cabinet and/or drivers.

DIY can take you quite far with a good choice of drivers and many hours, but you will most likely not touch M2 territory. For some, like me, that is fine as I prefer the 4” cores to the D2’s and understand that in using them I will sacrifice something else. Even my faithful M2 clones will be running 2451SL’s (D8R475Nd).

I’m only suggesting to try them. Someone here (LH) has tried them before and concluded that he preferred other horns. Your ears, your choice.

I also do have some brand new 2453SL’s and D2’s that I’m going to test (measure) in a few weeks on these WG’s and the M2 WG’s. I can post the finding here if of interest.

Kind regards
//Rob

[ivica]

Hi,

Some ideas can be seen here:
http://www.audioheritage.org/vbullet...l=1#post346443

If using up to 12kHz, may be JBL PT-H95HF , is something that has to be "investigated".
http://www.audioheritage.org/vbulletin/showthread.php?36528-Is-PT-F95HF-a-meaningful-sonic-upgrade-from-2332&p=371066&viewfull=1#post371066

may be
JBL sn/o:443495-001 waveguide ( as used in AM7215/95 box) called PT-H95HF-1, expecting the unit
price round 100$ is OK too.

regards
ivica

[sebackman]

Hi Ivica,

Albeit looking similar I do think there is a real sonic difference between the older PT wave guides (PT-F95HF) and the VTX F12 #5006815. I have had both and the newer certainly sounds better to my ears.

They do look very similar but when put side by side there are differences. The audible differences are much bigger than the optical.

Here is some info.

http://www.audioheritage.org/vbulletin/showthread.php?36686-New-JBL-waveguides-5006812-90x50-vs-PT-F95HF&highlight=new+jbl+waveguides

Kind regards
//Rob

[engineerjoe]

I am interested in all the JBL drivers that have come out since my touring days. I just got a pair of the neodium 1.4" drivers and the magnets are deteriorated bad. I scraped out all the filings and wiped off the diaghrams and now they work very well. I'm interested in how long that will last? It is disappointing since I'm such a huge JBL fan. I hope it is a small sample of what's out there that's hopefully still working fine.
I also just got a 2450 driver to compare with the old heavy 2446 2" ones that I have. ( yes I am way behind here)
I am interested in high quality sound but for pro sound reinforcement where they need to perform for many people.
I toured with INXS in 86' and the RH horns and drivers were the weak point of the sound system to me. The Martin low and low mid cabs were excellent. I was happier with my small sound system at home with the old 2441 drivers than the large system on tour.
With all the advancements in tech, I fell way behind and now being bored, I am trying out stuff I've missed.
Thank you for the great info here so far!

[ivica]

Hi Ivica,

Albeit looking similar I do think there is a real sonic difference between the older PT wave guides (PT-F95HF) and the VTX F12 #5006815. I have had both and the newer certainly sounds better to my ears.

They do look very similar but when put side by side there are differences. The audible differences are much bigger than the optical.

Here is some info.

http://www.audioheritage.org/vbulletin/showthread.php?36686-New-JBL-waveguides-5006812-90x50-vs-PT-F95HF&highlight=new+jbl+waveguides

Kind regards
//Rob

Hi sebackman,

Thank You for the link. It would be interesting to be seen comparable measurements PT-F95 vs ST825.
But any of them has to be used say over 1.5kHz. But such frequency can be a dispersion problem for 15" drivers.

Not to mention M2 driver to be applied. But for home listening 4" drivers, I believe can be used, may be even on the lower cut-off region.

regards
ivica

[Mitchco]

Some measures of a JBL 2453H-SL on STX825 waveguide crossed at 800 Hz: https://www.avsforum.com/forum/155-d...r-channel.html
Further down in the thread also a measure using a 2452H-Be driver - looks really good too.