JBL 2226J 2445J 2405 active DSP crossover help

[danvprod]

I found the 4343 reference thread and also this thread on 2405 crossovers. Above the resulting design.

On the 4343, there is an additional 10 ohm resistor parallel to the terminals. And note, the choke should be .12 mH, not 1.2, it's incorrect in my sketch.

This would give me 18 dB/octave and having the l-pad will let me tweak the level. That may be a good first step here.

1) Build crossover network for 2405, place in parallel with 2445 on 300B amps.
2) Sell both Crown D45 amps, purchase something new for the 2226s.
3) Investigate a replacement horn for the 2445 (or add damping to the current horn).
4) Add 16 uF protection HP filter to the 2445.
5) Finish crossover for 2445 (6-12 dB/octave LP filter; l-pad). Should the l-pad for this be 16 ohm? -- I'm looking at the JBL 4343B schematic here.

[danvprod]

I did find all of the network schematics here. And also learned something that I want to verify:
1) There really is only one version of the 2405, and it's not really 8 or 16 ohms, it is more like 10, even though it says 16 ohms.

Looks like there is 3 crossovers to look at for the 2405:

3155: http://www.jblproservice.com/pdf/Net...%20Network.pdf
3145: http://www.jblproservice.com/pdf/Net...%20Network.pdf
3107: http://www.jblproservice.com/pdf/Net...%20Network.pdf

The 3107 seems to be the most straight-forward. I don't know what the variable inductors are in the 3155 and 3145. But the 3107 seems to be closest to my previous post. 1.0 uF amp-side, .16 mH inductor and 1.5 uF speaker side with an 8 ohm l-pad.

3145/55 have bypass caps on the two caps, more resistors parallel to the load and what looks to be an adjustable inductor. Sorry I am a novice at this stuff. I appreciate all the help.

[grumpy]

I don't know what the variable inductors are in the 3155 and 3145

Fixed/tapped, not variable. Acts as an inductor element, impedance matching transformer/level shifter.

Hard to obtain exact replacements, and as you've noticed, alternatives exist

Difficult to DIY without a lot of learning about core materials, a winding jig, and some test equipment
(not on my bucket list).


... and yes, just the one 077/2405 at 10-12 ohms where it matters.

[berga12]

Dear Danv, pay a lot of Attention on "copying networks around".


for the 2405, do Streight forward, every schemathics is similar on every crossover, some use tapped autotransformer, some LPAD (see 3155 equivalent), but more ore less are similar, I use 1,5uF - 0,14mH - 1,8uF and my L pad is 4.3ohm series and 36ohm parallel.

for the 2445 you can concentrate on Low Pass, as I told you value like 0,48mH and 1uF could fit for a cut on top about 8-10Khz

for the High pass If you want to Run PASSIVE high pass, remember that every studio monitor cut the driver at 1,2-1,5Khz, and you need something around 400hz (theoretically 2xHorn Fc, means 250hzx2= 500hz....)

and for 400-500hz the value Are much bigger than the 4343 or 4355 filter... (notice that only 4350-55 have 2" Driver!!!! like 2445)

Yes you need an LPAD setup on 16ohm for 2445, Just search LPAD calculation and place 16ohm and the required Db attenuation -3 -6 -9 -12 etc... between 2405 and 2445 should be around 6/9db of difference.

This is always Just my opinion! Not a Must.

[danvprod]

Thank you, grumpy for the information on the tapped inductor. Yes, not going to deal with all that. The l-pad will work. I did noticed that there is a 20 ohm resistor in parallel with the 2405 in some of the schematics -- is that just for impedance control?

@berga12 -- thank you for your continued support and ideas. For the 2405 1,5uF - 0,14mH - 1,8uF is where I will go here. I'l likely do the variable l-pad, just to dial in the attenuation.

I'll do the protection cap on the 2445 (16-20 uF) and the 12 dB LP as you've suggested -- 0,48mH and 1uF

Can you expand on this set of filters? "cut the driver at 1,2-1,5Khz, and you need something around 400hz (theoretically 2xHorn Fc, means 250hzx2= 500hz....)" What do these filters look like? I could do this in my MiniDSP, likely. I don't want to go down the route of a passive HP and filters, just because of the price as you've stated. If I have some ideas about the Q, dB and center frequency for the 1,2 - 1,5 cut, and what to do around 400 Hz, that would be helpful. I could try that tonight in the MiniDSP.

Regarding the l-pad between the 2405 and 2445, are you thinking that the 2445 needs to be padded down more than the 2405 or the other way around? Either way, I'll likely get the variable l-pad at 16 Ohm for the 2445 and 8 Ohm for the 2405.

Many thanks again, and I appreciate you answering all my questions.

[berga12]

Just in my mind, if I remember well, 2445+Horn(kh55) is about 110-111db/W/m, the 2405 is about 105-106db/W/m realistic...

so depending on your ear sensitivity you have around 6db between 2445 and 2405. With a biamp in your case it could be that you don't need attenuation on the 2405 and you can go down with full mid high using your DSP and adjust level between the mid and super tw. Actually most of audiophile, or like Klipsh filter uses variable Autotrasformer only on Mid Driver.



You need an HIGH PASS done via your DSP and a protection cap, Around 400-500hz (theoretically 500hz, 2 times horn Fc)

___________________________________

JBL studio monitors (like 4350-55) uses the 2" driver from 1,2Khz to 10Khz, but this is not your case, so forget about this sentence and don't look at HP session in JBL studio monitors filter schematics.

___________________________________

I'm shure you will be happy with That, if possible in the meantime, use Crown D45 bridged on 2226J

[ivica]

Thank you, grumpy for the information on the tapped inductor. Yes, not going to deal with all that. The l-pad will work. I did noticed that there is a 20 ohm resistor in parallel with the 2405 in some of the schematics -- is that just for impedance control?

@berga12 -- thank you for your continued support and ideas. For the 2405 1,5uF - 0,14mH - 1,8uF is where I will go here. I'l likely do the variable l-pad, just to dial in the attenuation.

I'll do the protection cap on the 2445 (16-20 uF) and the 12 dB LP as you've suggested -- 0,48mH and 1uF

Can you expand on this set of filters? "cut the driver at 1,2-1,5Khz, and you need something around 400hz (theoretically 2xHorn Fc, means 250hzx2= 500hz....)" What do these filters look like? I could do this in my MiniDSP, likely. I don't want to go down the route of a passive HP and filters, just because of the price as you've stated. If I have some ideas about the Q, dB and center frequency for the 1,2 - 1,5 cut, and what to do around 400 Hz, that would be helpful. I could try that tonight in the MiniDSP.

Regarding the l-pad between the 2405 and 2445, are you thinking that the 2445 needs to be padded down more than the 2405 or the other way around? Either way, I'll likely get the variable l-pad at 16 Ohm for the 2445 and 8 Ohm for the 2405.

Many thanks again, and I appreciate you answering all my questions.

Hi
I think that our forum member 4313B has shown several solutions:

http://www.audioheritage.org/vbullet...l=1#post247755

I have been experimenting with the attached solutions with the following (Radian diaphragm)
2441Rad & 2311 & 2308 + 2405

Regards
ivica

[4343]

Are the TruExtent Be diaphragms available in 16 ohms?

Personally, I would double the 2226J for 8 ohm bottom and use 8 ohm diaphragms from the start, but you have what you have...

[danvprod]

Are the TruExtent Be diaphragms available in 16 ohms?

I do believe they are:
http://reconingspeakers.com/product/...m-16-ohm-copy/
$650/each though. Ouch.

http://www.parts-express.com/radian-...6-ohm--294-728
Radians may be another option, at $108/each.

Personally, I would double the 2226J for 8 ohm bottom and use 8 ohm diaphragms from the start, but you have what you have...

re: components -- I purchased all of this as a group -- the three sets of drivers and the horns. So I am not against upgrading certain items, but I largely have what I have as you've said and I want to optimize the components I have rather than replacing a lot of stuff.

[danvprod]

I put my 12 dB/octave crossover back on my 2405 this evening. This is a .3 mH inductor and 1.5 uF cap. These are both running on the 300B amps now.

What do you think about a Crown D150A Series II for the 2226? Seems like those are pretty reasonably priced and would work reasonably well. Also contemplating an Adcom GFA 555 or similar.

Emotiva A-300 may be a good option as well: http://emotiva.com/products/amplifiers/300

[berga12]

Just pay a lot of attention on 2405, ok 300b are around 4-5Watt, but in general 18db is suggested for 2405, you can try with another 1,5uF after the coil, 0,3mH seems a bit to high, maybe is just something on Q factor.


About low pass I would consider a minimum 400-500W into 8ohms, so you will have 200-250W on 16ohm, that's why I ask you if Crown D45 can be placed in bridge mode.

consider 2226h are 96db
mid high around 106db average

so you have to gain around 10-12db it means compared to 300b amp (if I consider 5W) that you need around 80-100W for the low, but If you think that normally we want a bit more bass due to ears sensitivity and due to Room loss, impedance curve,different input sensitivity of the amplifiers etc etc... Keep in mind good 200Wrms


how it sound now?

[danvprod]

Just pay a lot of attention on 2405, ok 300b are around 4-5Watt, but in general 18db is suggested for 2405

Yes, I plan on rebuilding this with the correct components. This was what I had on-hand to test out. I'll build the correct network next.

Crown D45 can be placed in bridge mode.

I can't bridge them -- I believe there is something you have to do internally to enable that. I'm not going to mess around with. I'd rather just sell them and get something new. I actually found a really excellent condition D150 locally for a quite good price. I am going to pick it up and give it a try so I can sell my D45s. I can always use that amp for my garage speakers if I get something bigger for the 2226s

how it sound now?

It sounds OK. I put a -3 dB cut @ 1.2 kHZ Q1 for the MF and am using a 500 Hz 24 dB/octave HP filter in the MiniDSP for the 2445. Still more work to do.

Best,
Dan

[Lee in Montreal]

Maybe a dumb question. But why not use a 24bd/octave filter which would allow to keep phase between drivers and perhaps even better protect the 2405 diaphragm?

Oups. Edit. The last reply mentions 24db filter. Sorry. ;-)

[danvprod]

Found this guy locally on craigslist today. Good shape and was able to get it for a really good price. Should hold me off for a while. Listen to Random Access Memories right now and it is definitely a nice upgrade over the D45. No trim being applied to either the 300B or the D-150 so that seems to be a pretty good match.

[ivica]

Maybe a dumb question. But why not use a 24bd/octave filter which would allow to keep phase between drivers and perhaps even better protect the 2405 diaphragm?

Oups. Edit. The last reply mentions 24db filter. Sorry. ;-)

Hi

	Fourth Order Linkwitz-Riley
	Fo=9000Hz
	UHF (10 Ohms)- High Pass Section
	C1=	0.94	uF
	L1=	0.11	mH
	C2=	1.88	uF
	L2=	0.50	mH
	VHF (12 Ohms) - Low Pass Section
	L3=	0.40	mH
	C3=	2.34	uF
	L4=	0.20	mH
	C4=	0.52	uF
	Sum at Fc=	0	dB
	Tweeter Polarity=		Normal