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Jbl - 8340 + 2226 diy

9K views 32 replies 8 participants last post by  Jesse S 
#1 ·
Built this yesterday. Sealed box for a single 2226J. It's about 2.8cu' and models in WinISD as -9db at 40hz relative to 90hz.


I'm using a Marchand XM9 to split the signal of the front left and right at 90hz and my Lexicon is set to "small" with mains crossed at 40hz so the bottom unit runs 40-90hz.


Right now the signal is summed to the single bass unit, when I build the second I can put it back to stereo operation.


It's running off 1 channel of my Parasound HCA1206. It has no 16ohm spec, the 80hm spec is 125 watts so it's maybe giving it about 70 watts.




Even with this "pawltry" amount of power I haven't seen the clip light even flash at volumes peaking over 105db. Can probably thank the generous 97db efficiency for that. A pair of these should be a monster as even the single is enough in my room. Why the hell did I buy 6 of these



Edit: when I have stereo units I'll probably increase the crossover to 200 or 300hz to let the 2226 do all the mid-bass and let the 127H2 in the 8340 focus on the mid-range.
 
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#2 ·
Nice.


This is what I think of as 'ye generic HE 3 way', a good 15 and a 6.5-10" mid with a CD+WG. JBL drivers were a long standing fave (and add a stack of 18's below and you had my PA) but they now split the role with AE's in the same format for surrounds, and a JBL/B&C combo coming for the bedroom.


Do yourself a favour and get the xover up to 250-300Hz or so, plug the ports on the 8340 and enjoy.
 
#3 ·
neat...are you running subwoofers with this setup?


if run sealed, you might want to apply some boost to give you a -3db point of around 60hz, then cross them to some subs, doesn't really matter what type. the suggestion to run them up to 250-300hz is a good one...minimum of 175hz for sure.


while heresy around here, since you have so many of those drivers, you could use three of them in three ported enclosures (~6 cubic feet ea.) tuned to around 22hz for your subs. that would give you >120db from ~20hz up, which is a lot. and since you don't appear to need a ton of spl, you could probably get away with running the three off a 500 watt amp (3x16ohms in parallel is ~5.3 ohms).
 
#4 ·

Quote:
Originally Posted by LTD02 /forum/post/21453118


neat...are you running subwoofers with this setup?


if run sealed, you might want to apply some boost to give you a -3db point of around 60hz, then cross them to some subs, doesn't really matter what type. the suggestion to run them up to 250-300hz is a good one...minimum of 175hz for sure.


while heresy around here, since you have so many of those drivers, you could use three of them in three ported enclosures (~6 cubic feet ea.) tuned to around 22hz for your subs. that would give you >120db from ~20hz up, which is a lot. and since you don't appear to need a ton of spl, you could probably get away with running the three off a 500 watt amp (3x16ohms in parallel is ~5.3 ohms).

I believe Jesse has the sub thing handled by running 4 Avalanche 18's in an IB.
 
#6 ·
Yep, avalanches.


So the JBL models as -9db at 40hz, does room gain offset any of that?


I'm looking forward to crossing the 2226's higher but I need to build the 2nd unit so everything isn't mono below 200/300hz.


Sealing the 8340's sounds like a good idea too. I tried that last week just to see how they'd sound (without the 2226) but the extension went out the window and they sounded anemic.


The 8340+2226 combo is good by itself for music. It sounds like a really good, really big speaker.


I guess there isn't much need to port the 2226 in a home environment, especially with a subwoofer to cover the bottom.
 
#7 ·



Finished the 2nd unit. I swapped in a Rane AC23 running in 2 way stereo. Currently it's crossed at 225hz and runs down to 40hz.


With just ~70 watts per driver from my Parasound 1206, the output is sufficient for full reference. Coupled with the IB, I finally have clean output across the full spectrum. I've had good subs for many years but never this level of mid-bass. I can see how people would be very happy with the 4pi as their front 3 speakers.
 
#9 ·
The pair is great for movies, but...




I found a pair of 4508 cabinets for sale locally.


A friend of mine has 2 more pairs of 8340's for sale. I could either get those for full 7 channel or think about getting some higher end compression drivers+horns for the left and right channel. Are there any reasonably priced, used JBL CD's I could get?
 
#10 ·
Drivers installed. Ludicrous headroom.

 
#12 ·
I think I'll block the ports. The sealed units sounded better.
 
#14 ·
You're thinking of something else, the 8340 are surrounds with 127h2 10" woofers and a CD that I can't find any model info for.
 
#16 ·
I am using JBL 8340's for my front L,C,R and just love the sound from them, but one of my horns has lost output. It still plays, but the sensitivity went way down, about 6 db. I checked all the usuall things first, even all the x-over components because I have never seen a driver go down so much in level without distortion from rubbing or cracks. But as it turns out, I swapped the horns and the problem followed the horn. So if anyone on here has an extra 8340 horn they would like to sell I am interested.
 
#18 ·
This driver does not look like mine. My driver is not threaded onto the horn, it has I think 3 screws around the flange into the magnet assembly with the v.c. / diaphram assy. sandwiche between the magnet and horn. From some of the info I found on the web, it seems this horn/driver assy used in early 8340 speaker was made by Pyle for JBL. I am striking out on a replacement so far.
 
#19 ·
I pulled the part number from the JBL service manual. If it's different, I'd suggest you contact JBL and give them your unit serial number and see what they say. They may have spares.
 
#21 ·
So it's not a 2412? That was the number I found a few days ago when looking for info.


The 8340 are pretty good as mains, but crossed higher with 2226's doing
 
#22 ·
My system is currently on the budget side with just the 8340's for the mains and a single LFE + bass redirect 18" ported sub with a bridged 600 watt JBL 6260 amplifier. I am currently crossing out of the 8340's at 60 hz to the common sub. I have drawn up plans for a custom speaker cabinet / baffle wall to house all the LCR and sub components and also be a screen frame, but that is a future project. For now I need to get this HF horn issue figured out.


I have a JBL technical manual for the speakers that is dated April 04 and it does match my speakers perfectly. The horn is marked as part number 336812-001 3/4 inch voice coil horn assembly. Here is the PDF tech manual...

http://www.jblproservice.com/pdf/The...eries/8340.pdf


The JBL driver replacement recomendation still lists this as a "current model" and no recomended substitute, so I guess I can try ordering it from JBL and see what they will hit me for it. It is not marked, but on another web page it did say made by Pyle for JBL.


Thanks for trying to help, and keep an eye out if one does show up.
 
#23 ·
Just hunting for small horns with similar spec, I found this.

http://www.mcmelectronics.com/produc...m_term=53-1260


It is a little smaller, so I will need to make a mounting ring, it loses about 2 db of sensitivity, but gains a lot more power handling. I really wonder how it compares on distortion?? Going from a 0.75 inch aluminum dome to a 1.35 inch titanium dome should help. Magnet also goes from 15 to 20 OZ, but I know gauss in gap means a lot more than plain weight. The price is hard to beat, I can buy 1 to just beat it up and see how it sounds before I commit to 2 or 3. I could just use the new one for Center and use my remaining good pair on Left/Right. My center is playing through a cloth screen, so I already have a little different tamber which I correct with EQ.
 
#24 ·

Quote:
Originally Posted by GXM /forum/post/21616615


I have a JBL technical manual for the speakers that is dated April 04 and it does match my speakers perfectly. The horn is marked as part number 336812-001 3/4 inch voice coil horn assembly. Here is the PDF tech manual...

http://www.jblproservice.com/pdf/The...eries/8340.pdf


The JBL driver replacement recomendation still lists this as a "current model" and no recomended substitute, so I guess I can try ordering it from JBL and see what they will hit me for it. It is not marked, but on another web page it did say made by Pyle for JBL.


Thanks for trying to help, and keep an eye out if one does show up.

Email JBL and ask, the CS is usually very good. Also email any of the authorised resellers, like the one I linked earlier with the JBL part number, and what it's out of.

Quote:
Originally Posted by GXM /forum/post/21616745


Just hunting for small horns with similar spec, I found this.

http://www.mcmelectronics.com/produc...m_term=53-1260

It is extremely unlikely to work with the original passive xover. Just buy the JBL part as you can't randomly substitute other drivers into xovers not designed for them.
 
#25 ·
I have done a bit of hunting so far and since this particular version of the 8340 has been discontinued since about 2005 I may be out of luck on a new replacement. The 8340A with the plastic cabinet and screw on driver came out before 2001, and I think the wood cabinet version changed over to the newer driver in the same time frame before they stopped making it alltogether. If one does turn up, I will use it.


Until I can find one though, for $12 each, I think this one might get me in the ball park.

http://www.mcmelectronics.com/product/53-1270


I have been a cinema sound installer for many years, and I know the different driver specs, even though small in this case will result in a different slope and balance especially around the x-over frequency. If I was trying to match other speakers, it could be a problem, but since it is just my 3 single speakers, and I have Eq for each one, I do not think the issue will be a problem at all. Worst case, I might have to adjust the impeadance matching section of the x-over. And since I have the full schematic of the x-over, I should be able to work that out once I sweep the new driver. At this point I think I am going to try the new horns in left and right, keep the JBL one in center and see how they compare. This will also give me a good spare for the center channel.


I just did a frequency sweep on the left and right horns, the level out of them is over 6 db different at the same drive voltage, and the current is almost identical. It appears the magnet has just lost it's strength. Just sticking a hunk of metal on the back and pulling it off, it sure does feel a lot weaker. I have never had a speaker demagnatize on me before.
 
#26 ·
Looks like I caught a lucky break. I located a single new old stock 8340 horn. It is on it's way to me. According to JBL it is no longer going to be made, so I hope this one holds up.


In case your curious... I used a tone generator set to 2,000 hz, at about one volt out. Connecte the good horn from the left speaker and measure just over 93 db at a little over a foot away. I swapped to the bad horn and the level was 79 db, or 14 db less at the cross over frequency. OUCH!! As I went up in frequency, the level difference did shrink a little, but even up at 10,000 it was almost a 10 db difference. No Eq is going to make that driver useable. The Audessey DSX XT sure tried though, cranking every band above 3 K right to the top.
 
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