Q regarding JBL large format drivers and horns

[doucanoe]

I am in the process of putting together a new 2-way. In the past, I have owned and enjoyed (still do) my ALtec driver/horn combinations but for this project JBL is the deal.

My original plan was to use a pair of EV SP15's for woofers but the cabinet volume necessary to do it right would be too overwhelming in my small listening room. Now I would like to use a pair of JBL 2225's or 2226's to keep the cabinet build to around 3-5 cu-ft. The horns I will be using will be the JBL 2380A 2" large format.

I have been reading about the pros and cons here and elsewhere regarding the JBL 2445J CD and am looking for other opinions. From what I "understand" these can get a little edgy or bright without compensation or EQ. Im open to suggestions and alternatives. I have already checked with Great Plains and the 399 with a adaptor might be on order. I will loose my high end though because of the 15khz roll off.

I guess my initial question is this. Has anyone had experience with the 2445J with both SS and low power tube amps sound wise? If its just a little harsh on the highs because of some SS home or pro amps, driving them with tubes might provide a little different sonic presentation.

RC

 

[Zilch]

I went through a similar exercise about a year ago. For the flat-front biradial 2380A horn, I have to accept that the improvements made (coherent phase plug, et.al.) in the most recent designs of JBL's large-format drivers are real, and worthwhile. Indeed, 2446 plays effortlessly with surprising competence using the original compensation provided by 3110A passive crossover with HF boost, or 5235 active crossover with FFBREQ (Flat Front Biradial Equalization) contour cards installed. Note that this is not the straight-line CD compensation provided standard in many active crossovers and some amps. That'll work, just not as well. JBL's more recent M552/3 actives have the correct curve enableable via internal jumpers.

Comparing the response curves, I opted for the neodymium-magnet 2450, instead, acquiring a pair with dubious diaphragms on eBay for $600. No matter the diaphragms, since I moved directly to the latest-technology damped titanium "SL" variant (16-Ohm "J" version for use with 3110A) for improved sound quality. Those show up on eBay from time to time for reasonable prices also. (Se habla español.) Know that plain titanium is deemed "unlistenable" by many who have pursued these same design objectives. Never having done more than a cursory comparison in large-format, I can't say for certain myself, but I DO know which path JBL has subsequently chosen to follow.

My "thing" is two-way, and it is apparent that this combination may well be amenable to further (custom) compensation for flat response out to 20 kHz. In fact, it came as a bit of a surprise; I was expecting the 4" diaphragms not to have the VHF extension of the smaller formats I had been working with previously. Not so -- they do it with ease. At the time, however, I was developing a three-way crossover for other uses, and my large-format 2380A system ended up also incorporating the new neodymium 2407H UHF driver on JBL's $10 90° x 50° progressive transition waveguide as a tweeter, matching the 2380A's dispersion pattern at crossover. The system is dead flat out to 20 kHz and beyond, so I have not further pursued working it into a two-way. The crossover is documented at LHF.

Zilchster's bottom line: Move directly to the latest technology unless you have some VERY specific purpose for using the old stuff.

Note: "Tuning" systems by amplifier selection is recipe for madness, in my view. Get it right from the start, they'll resolve differences among amplifiers, and you'll have options....

 

[doucanoe]

Comparing the response curves, I opted for the neodymium-magnet 2450, instead, acquiring a pair with dubious diaphragms on eBay for $600. No matter the diaphragms, since I moved directly to the latest-technology damped titanium "SL" variant (16-Ohm "J" version for use with 3110A) for improved sound quality. Those also show up on eBay from time to time for reasonable prices also. (Se habla espanol.) Know that plain titanium is deemed "unlistenable" by many who have pursued these same design objectives. Never having done more than a cursory comparison, I can't say for certain myself, but I DO know which path JBL has subsequently chosen to follow.

Zilchster bottom line: Move directly to the latest technology unless you have some VERY specific reason for using the old stuff....

Might just be that the 2450 is what I'm after then. I read much about the 2450 and yours and other opinions on Lansing but I was having trouble sorting through the diaphram thing. I guess what you are saying is that the 2450 might be the ticket but may or may not have the diaphrams I'm looking for?

In any case, Im going to the "library" and see what the specs say for the stock 2450 dia.

Currently as you may or may not know, I am using active x-over and biamping. For these Im really leaning tword passive but that a whole new can of worms for me. Looking at your x-over, was that something stock from JBL or was that a Zilch build? It would be fun to sort it out and build my own but the whole x-over thing is still a mystery for me.

At this point, you could lock me in a room with all the necessary components and schematic, tell me to build it, come back in a week and I would be still sitting there scratching my head.

RC

 

[Zilch]

Those are Zilch-design three-way crossovers.

Yes, there's a two-way version with HF compensation, but I haven't tried it with those drivers and horns.

Here's the 2446 and 2450 specs I compared:

http://www.jblpro.com/pages/pub/components/2446.pdf

http://www.jblpro.com/pages/pub/components/2450.pdf

And here's a plan:

Buy used 2450s with whatever diaphragms in them.

Run them on JBL 3110A crossovers with HF boost. You'll need an L-Pad for each driver in between, maybe, depending upon the woofer. I had to pad down 6 dB using the 2235H woofers shown.

Two-ways done.

Watch for 16-Ohm "SL" diaphragms to upgrade. Buy new, if you have to: D16R2451SL, $194 each.

Think about going three-way while you enjoy those.... :thmbsp:

 

[Zilch]

Here's my current kick-ass large-format two-way:

2452H-SL on PT-F95HF, LE14H-3.

Still tweaking the crossover.

[It's too "hot" at 23 kHz.... :huge: ]

 

[doucanoe]

Here's my current kick-ass large-format two-way:

2452H-SL on PT-F95HF, LE14H-3.

Still tweaking the crossover.... :huge:

Now thats what I'm talkin about!

RC

 

[Zilch]

Now thats what I'm talkin about!

Well, if you'll settle for 3" medium-format, you can get pretty close for ~$1500 a pair or less:

2435HPL, PT-F1010HF, LE14H-3, Zilch's "Gauntlet" compensation filter, biamped.

That system's out on loan right now, for evaluation.

It COULD stop in Twin Cities on its way back from Virginia, I suppose, but only briefly....

 

[macaltec]

 

[doucanoe]

Well, if you'll settle for 3" medium-format, you can get pretty close for ~$1500 a pair or less:

2435HPL, PT-F1010HF, LE14H-3, Zilch's "Gauntlet" compensation filter, biamped.

That system's out on loan right now, for evaluation.

It COULD stop in Twin Cities on its way back from Virginia, I suppose, but only briefly....

Certianly appreciate the offer and would love to hear them. However I probably wouldn't have the time to really give them their due at this time of the year. We will be talking more x-over talk in the near future as I gather more goodies my friend. Keep in mind that the experience will be somewhat similar to trying to teach chess to a monkey though.

 

[Zilch]

O.K., another option for you, which I'm running right now, pretty close to the "Now thats what I'm talkin about!" performance above:

JBL's new PT-F95HF waveguide, PN 338650-001, $98 ea.
BMS #4555 1.5" compression driver, $117 ea.

Specs here: http://www.assistanceaudio.com/02_bms.html

Cross at 1 kHz, plus a simple compensation filter I'll give you via PM if you get this gear. Still tweaking it.

FR curve today below, as I say, is pretty close:

 

[doucanoe]

Well, I found a solution. Maybe not "the" solution perhaps but I think they are going to be interesting. They will be on the EV HP940 horns and I believe that I will try running the Altec 291-16k's with the JBL 2380A's. Both setups will be utilizing a active x-over.

Sorry, no test data will be or can be provided but I will let you know how I like them :yes:


RC

 

[Zilch]

Does your active have CD compensation?

Data sheet says you'll need to use it.... :yes:

 

[doucanoe]

I haven't purchased another (active x-over) yet and havent completly sorted out which woofers I will be using. Im sure that this one will not be completed until at least mid/late summer.

Any suggestions?

RC

 

[Zilch]

Any suggestions?

Every active crossover manufacturer's CD compensation I've measured seems to be different. I note EV prescribes different cards for each driver/horn combination, JBL 2380 not being among them, of course.

You may have to make an empirical determination requiring measurement capability. Start with EV tech assistance, maybe....

 

[doucanoe]

Every active crossover manufacturer's CD compensation I've measured seems to be different. I note EV prescribes different cards for each driver/horn combination, JBL 2380 not being among them, of course.

You may have to make an empirical determination requiring measurement capability. Start with EV tech assistance, maybe....

Actually, I have sopke this those guys locally before and they were very helpful. Im going to run it by them and see what they say.

Im sure that they would have some ideas regarding using the DH1A's and the HP940's.

RC

 

[similost]

O.K., another option for you, which I'm running right now, pretty close to the "Now thats what I'm talkin about!" performance above:

JBL's new PT-F95HF waveguide, PN 338650-001, $98 ea.
BMS #4555 1.5" compression driver, $117 ea.

Specs here: http://www.assistanceaudio.com/02_bms.html

Cross at 1 kHz, plus a simple compensation filter I'll give you via PM if you get this gear. Still tweaking it.

FR curve today below, as I say, is pretty close:

Hey Zilch, the compensation filter you are talking about here... was that part of the M19 crossover schematic you gave me, or is this something completely different?

Yeah yeah... sorry about digging up an old thread :

 

[Zilch]

Three years ago, it may well have been the bridged-T HF comp filter used in the Altec Model 19 crossover, yes, but I dont recall having the crossovers themselves at that time....

 

[theebadone]

I went through a similar exercise about a year ago. For the flat-front biradial 2380A horn, I have to accept that the improvements made (coherent phase plug, et.al.) in the most recent designs of JBL's large-format drivers are real, and worthwhile. Indeed, 2446 plays effortlessly with surprising competence using the original compensation provided by 3110A passive crossover with HF boost, or 5235 active crossover with FFBREQ (Flat Front Biradial Equalization) contour cards installed. Note that this is not the straight-line CD compensation provided standard in many active crossovers and some amps. That'll work, just not as well. JBL's more recent M552/3 actives have the correct curve enableable via internal jumpers.

Comparing the response curves, I opted for the neodymium-magnet 2450, instead, acquiring a pair with dubious diaphragms on eBay for $600. No matter the diaphragms, since I moved directly to the latest-technology damped titanium "SL" variant (16-Ohm "J" version for use with 3110A) for improved sound quality. Those show up on eBay from time to time for reasonable prices also. (Se habla español.) Know that plain titanium is deemed "unlistenable" by many who have pursued these same design objectives. Never having done more than a cursory comparison in large-format, I can't say for certain myself, but I DO know which path JBL has subsequently chosen to follow.

My "thing" is two-way, and it is apparent that this combination may well be amenable to further (custom) compensation for flat response out to 20 kHz. In fact, it came as a bit of a surprise; I was expecting the 4" diaphragms not to have the VHF extension of the smaller formats I had been working with previously. Not so -- they do it with ease. At the time, however, I was developing a three-way crossover for other uses, and my large-format 2380A system ended up also incorporating the new neodymium 2407H UHF driver on JBL's $10 90° x 50° progressive transition waveguide as a tweeter, matching the 2380A's dispersion pattern at crossover. The system is dead flat out to 20 kHz and beyond, so I have not further pursued working it into a two-way. The crossover is documented at LHF.

Zilchster's bottom line: Move directly to the latest technology unless you have some VERY specific purpose for using the old stuff.

Note: "Tuning" systems by amplifier selection is recipe for madness, in my view. Get it right from the start, they'll resolve differences among amplifiers, and you'll have options....

dang zilch, those look like a really serious build. I would love to hear those, what are you pushing them with?

 

[theebadone]

home brew valencias

I'm gonna be putting another set of speakers together by the end of this week also. Right now i'm just waitin on my components to come back from the rebuild shop. Which will be a set of 416-As, 802-8A, 511B and an Altec model 19 xo with new caps. I intended to use these in another A-7 build, buttt can't find another set of decent cabinets. So thanks to a friend i found a decent set of valencia cabinets to stuff the components in. The 416s are getting reconed and new voice coils, the 802s are getting remagged and new diagphrams and caps, the 19 crossovers are getting the full treatment too. I will switch out the 511s for the 811s i have on the A-7s, and install everything in the valencias. And i'm crossing them at 500 hz. this time, just like the factory originally did with those components. At least until i find another set of A-7 cabinets.

 

[Zilch]

dang zilch, those look like a really serious build. I would love to hear those, what are you pushing them with?

JBL 6260.

And i'm crossing them at 500 hz. this time, just like the factory originally did with those components. At least until i find another set of A-7 cabinets.

Model 19 is 1.2 kHz, and as Altec later decided, 811B is a 1.2 kHz horn; do that. Move up to 902-8A for extended HF response.

Similarly, 511B is an 800 Hz horn by contemporary standards. Yeah, it'll "push" to 500 Hz for PA, but....