My new 4430 system [Archive] - Lansing Heritage Forums

3dbdown

05-04-2008, 12:11 AM

OK, guys....I need you expertise and help!!!

I've just got my 4430's installed in my room, and wanted to ask the forum's advice.......

I'm running the pre-amp outs of my Marantz 2325 into a dbx 231 equalizer, to try and get rid of an annoying room node I have. From there, into my dbx electronic crossover, at about 1164hz (JBL Internal xover @ 1000hz) and from there into my QSC RMX 850's. Keep in mind, I run this gear 'cause I already have it, and after buying the 4430's and my C70 Alpha 1's, I'm out of sheckels for the time being.

So, here's the scenario: My room is about 14 by 25 feet, all solid wood tongue and groove, except for my basss wall, which is covered in mortar and brick. I have concrete floors, carpeted. So far, so good. Windows are small, evenly spaced, up high, with a patio slider covered by plastic vertical blinds, right in front, and at right angles to my right speaker.

Now, the bad news.....I have a round brick gas fireplace, about 4 feet in diameter, 19" high, 4 and 1/2 feet out from and centered in front of my bass wall. Speakers are about 9' apart, toed in about one inch each, and I'm sitting 9 feet in front of them. Bad news is, the fireplace is there. The good news, I guess, is that at least it's round !!

Then, my equipment, which cannot change location, is mounted on two wooden cabinets along the bass wall......Yicccchhhh. But, my plan is to get an open 19" rack, about 5-6" tall, leave the bottom 3 feet open, and rack mount everything else above that. I THINK that will do the trick.

Then I have a 2 foot screen between the top of the fireplace bricks and the hood/flue/chimney. The screen roughly coincides with the horn dispersion on the 4430's, so I guess I got lucky again. I'm guessing I have a standing wave in the 9" dia. chimney, but I haven't noticed any issues with it thus far. And the chimney is round.

The EQ took care of the room node, sort of, somewhere between 3 and 5 khz, I figure due to the wood panelling. By the way, the ceiling is also wood, and has a slight slope accross the plane of the speakers, ranging in height from 8'8" to 8'10", which I suppose is a gift horse I dare not look in the mouth!!

Although I don't quite have the node tamed yet, I'm hot on its trail. I get a few reflections in the ceiling beam pockets, but not early reflections....although interesting sonically, they are not a problem!!

I had one heck of a time all last week trying to place the speakers so I could get some bass response. After trying every position from 1 to 3 meters out of the corners, with no luck, I finally shoved them directly in the corners !!!

Problem solved, though I'm damned if I know why. Well, if it sounds good, so be it.....Right ???

So, now I have a reasonably good sounding setup, but I'd appreciate any comments or suggestions from the forum as far as how to tune it up a little better.

I'm listening to Seal's first cd right now, which I've used as well as between-the-station FM white noise to get the system to this stage.

Turns out, of my 500 cd's, I can throw 496 of them away due to rotten mixing/mastering..........What a revelation !!! I LOVE THESE MONITORS, AND IF IT KILLS ME, I'LL GET 'EM RIGHT!!!!! CAN'T THINK OF A BETTER WAY TO GO, CAN YOU??????

This is without a doubt the hardest pair I've ever set up. Makes me love them all the more..........They are the absolute naked truth!!

My friends at JBL thought, in terms of re-sale value, that I paid too much for them..............But, considering that I WILL NEVER GET OFF THESE 4430's, that is a moot point.

Anyway, my new found friends, I would appreciate any comments or suggestions you may have regarding my setup,

Thanks in advance,

Rick

John

05-04-2008, 12:20 AM

Nice discription,but ???

:useless:

Well maybe not worthless but pictures would be nice. :blah:

clmrt

05-04-2008, 06:05 AM

Are they on the long wall or the short? And, have you tried just skipping all that gear and just run them with a pre and an amp?

3dbdown

05-04-2008, 10:39 AM

Thanks, John and clmrt...

Yeah, pix will be forthcoming as soon as I tear myself away from my listening chair!

The monitors are on the short wall, and room furniture layout dictates they remain there.

I did start out with just the pre-amp out, but needed to fix the room node. I also ran the Marantz power amp to the cabs, but quite honestly, I preferred the sound of the QSC's....They just really woke up the monitors.

Problem with using the tone controls was that when I got rid of the offending frequency, was that I also got rid of most of the other midrange as well! Just too broadbanded. It really is much better than it was, and I may be closer than I think to optimum sound for the room. I needed to give my ears a rest last night, so today I will re-evaluate the system.

The EQ and crossover do allow me to regulate the top-end level without losing the overall picture.

Actually, I just turned down the high crossover level a taste. Obviously had ear fatuige last night.

Today's another day! I'll work on the pictures! I have not posted photos here, and would appreciate any info on max sizes so the aren't too large, but show up reasonably well....http://audioheritage.org/vbulletin/images/icons/icon5.gif

Rick

johnaec

05-04-2008, 11:57 AM

I thought the 4430 had special crossover circuitry that gets removed when biamping, and that this has caused many to find they liked the sound better using the internal crossovers instead of biamping. I run my 4430's with the internal crossovers and am totally happy with the sound.

John

3dbdown

05-04-2008, 12:46 PM

Johnaec.....

Your point is well taken........

They do have fine crossovers, and sounded fine to me internal as well.

However, my listening enviornment is a little too bright, and I wanted a way to control the hi-freq level evenly without changing anything else. EQ alone was simply not the answer. Nor was adjusting the network L-pads. I like to set those up in a particular way, then, once the cabinets are set up, I leave them alone.

So, bi-amping in my case is essentially for purposes of volume control. The frequency selection on my crossover is stepped, and I'm just trying now to decide on 1048hz or 1164 hz, leaning toward the 1048 hz mark. Once satisfied, I'll measure the frequency for accuracy, as my estimate of frequency is based on doing the arithmetic for the detent positions on the selector switch. Mark and Greg agreed they could be crossed over anywhere from 900 to 1200Hz, end encouraged me to experiment with the crossover point.

It' all about control, and I now have lots of options in getting everything dialed in.

Bi-amping doesn't eliminate all the internal network components anyway on the 4430.

Greg Timbers and Mark Gander were the first ones to tell me that bi-amping would not gain me much, in the traditional sense of why one does it in the first place.

In my particular situation, however it is working extremely well. This is a tough system to set up properly, and I've had to use all the tricks!!

I can see why some people don't like the sound of this system, and I personally believe that may be because they just don't put forth all the necessary time or effort to get it right.

This is high-end stuff, and Like a Ferrari or a Steinway....It has to be properly tuned up. It deserves all the attention a user can provide.

I'm staying on it, and the rewards are great, and getting better every hour!

johnaec

05-04-2008, 12:55 PM

So, bi-amping in my case is essentially for purposes of volume control.What would be nice to try is one of the JBL 5235 crossovers with the special 4430 cards. 'Been looking myself...

John

3dbdown

05-04-2008, 01:53 PM

Yeah, that would be way cool, but I haven't found any. So, I use what I have. It's like they say in racing "you run what you brung"!

Of course, the beauty of this whole thing is, I will never be really "done" with the system, in the classical sense. And the 4430's definitely point up the weaknesses in the rest of the system. I don't fully know what those are yet, but it's a labor of love, and no matter what I do in the future, the cabs will always do the job.

First thing I am going to do, though is change the cables among the electronics. They are old, not very expensive, and left over from the studio days. There's much better stuff out there, and if I am going to keep the setup I have, that is the first order of business.

I've heard there is a mod card for the JBL crossover that does an 18db rolloff......Know anything about that? I've always had 12db stuff...seems to be a standard. But, in case I do find one, it would be good to know.

I also don't currently have the bottom end rolled off, and I need to do that. THe crossover I'm using will do it at 40hz, and then I also have selectable 30hz or 50hz filters in the QSC power amps. Just trying to figure the best choice. I am inclined toward the 30hz filter at the power amp, but would appreciate any thoughts.

Rick

Fred Sanford

05-04-2008, 03:39 PM

I also don't currently have the bottom end rolled off, and I need to do that. THe crossover I'm using will do it at 40hz, and then I also have selectable 30hz or 50hz filters in the QSC power amps. Just trying to figure the best choice. I am inclined toward the 30hz filter at the power amp, but would appreciate any thoughts.

Rick

Double check me on this, but I was a bit surprised recently when the QSC's 30Hz rolloff was what it said it was, but the 50Hz rolloff also included a slight 100Hz boost...take a look at the fine print:

3dbdown

05-04-2008, 04:37 PM

Fred Sanford

05-04-2008, 05:29 PM

Hi, Fred..

Pardon my ignorance, but I'm not sure what your are suggesting. I had already decided not to use the 50hz precisely because of the bump. But am I ok with the 30hz filter, or am I better off using the other options in the signal chain, which are:

1) 40hz high-pass on my EQ

2) 50hz, 12db.octave lo-cut on my Crossover

I just want to keep as much of the low frequency in the 4430's as I can. They start to roll off at 35hz anyway, I think.

Rick

Sorry, I guess I wasn't suggesting anything, just pointing out the 100Hz bump. Personally, I'd probably use the 30Hz filter on the power amp, figuring I'd be looking for a fully parametric EQ in the future to get a better handle on the room issues. I think Meyers are a forum favorite lately, I personally have AudioArts, but for a different application. Sorry I couldn't be more help.

By the way, I checked the loose drivers I have around, and so far no "12"s...sorry! I'd be proud to own one, though, and am glad you've made your way here.

je

3dbdown

05-04-2008, 07:40 PM

Fred,

thanks for giving me a couple of units to check out....

I had actually, right after our exchange, engaged the 30hz filters on the QSC's, and they definitely have the least noticable difference in sound so I'll stick with them.

Yeah, parametric would be ideal, and I was pondering that the other day....oh well, something for the not too distant future! Everything sounds better right now, so I'll enjoy them, and tackle the remaining issues one at a time till it's right.

Right now I notice that scratchy pot in one of them, the mid freq, level pot, acting up a little. It's been giving me trouble setting the mids exactly where I want them. I have to figure out how to get to it though. The JBL foilcal covers the mounting screws, and doesn't look like any fun to remove or re-install.

Not sure if I can get to it with drivers removed or not. I'm hoping it just needs some De-Oxit, but it could be burned....I just really don't want to mess up the Cabs, as they are in virtually pristine shape.

Rick

oznob

05-04-2008, 08:39 PM

Hi Rick,

Johnaec has my old 4430's which I would still have if my wife was a bit more understaning! I think her first comment was, "what the hell are those things doing in my living room?" I am very lucky now as she really likes the look of the S3100's. Oh, she told me the other day that they sound very "nice!" Hey, I'll take what I can get!:thmbsup:

Have you looked into some room treatments to tame it a bit? They make some very decor' friendly designs these days and that may help getting things calmed down.

As far as cables and wires, there maybe something to good shielded cables and wires but most of it is marketing IMHO. There is a huge mark up on high end cables as well. I wonder if that is why they push them so hard?:hmm: A friend of mine made my speaker cables out of 14 gauge OFC copper and some nice interconnects that are mylar shielded. They work great for me and cost me under $50.

Good luck with the 4430's. They are great speakers and have a lot of fans on this forum!

oznob

05-04-2008, 08:56 PM

http://www.echobusters.com/

Echobusters room treatments have been used by my Uncle who does home theater installations. He tries to make his systems work without them if at all possible but, in very lively rooms, he has had great success with them.

Mark

3dbdown

05-05-2008, 11:47 AM

Thanks, everyone for all your help....

It works! I took the room node out with the 1/3 octave EQ, although I will now try to get parametric with it, since I found the offending frequency finally. I checked out the Meyer, and it looks like a sweet unit indeed.....just wondering if I can buy or build a single filter to do the job.

Also used a couple pieces of foam I had from the studio on the walls either side of the cabs, and it really helped. Am now able to use the Marantz tone controls for slight treatment based on the particular mix I'm listening to.

I also removed the elctronic crossover, as the EQ treatment was successful......and although it was a fun experiment, I really do like the internal xover setup better. I will still change out my cabling though, and I think I'll build those myself.

So, once again, I find simpler is better!!

Still have to get after that dirty L-pad, and today will remove the 2235H and will hopefully, with the aid of a light and a mirror, see if I can't get the De-Oxit in there to sweeten it up.

Thank you ALL again! :bouncy: :applaud:

Rick

grumpy

05-05-2008, 03:16 PM

foil-cal removal (should you need to):
I've used a ~3"-wide spackle knife + heat gun (or blow drier and patience)
to cleanly remove the thick (foil-cal-wise) L-pad cover without marring the cabinet.

http://www.jblproservice.com/pdf/Studio%20Monitor%20Series/4430LR.pdf

used an oven mitt the second time... :p

Interesting DIY project source (e.g., parametric EQ):
http://sound.westhost.com

3dbdown

05-05-2008, 04:22 PM

Thanks Grumpy,

Hoping I won't have to do that, but now I know how.....

Interestingly, when I pulled the knob off the L-pad, things settled down a bit. I noticed the L-pad shaft was a bit cocked in the baffle cutout, and am now wondering if stress on the shaft may have been highlighting the problem. Not familiar with the mechanical construction of the pot, whether or not contact position could be affected so I'll still try De-Oxit. Wanted to get to that step today, but events took over and was not able to.

I can't imagine JBL finished goods QC missing that, so maybe it's been tampered with subsequently. Anyway, thanks to your advice, I'll prevail one way or the other.

Question now is, if I have to replace the L-pad, are they still available? If not, I will need another source/advice for a replacement.

Although I don't hear anything that I would not attribute to a dirty pot, I really hope the diaphragm is OK. Hope those replacements are available, and I would not consider other than JBL......maybe edgewound knows, and I am fairly close to him....by California mileage standards anyway!!!

I suspect they are fine, however, based on their sound, so I won't go looking for trouble!!

Rick

oznob

05-05-2008, 06:55 PM

It's a great feeling when you finally get your system dialed in, congrats Rick!:applaud: I am a big fan of two ways done right. I put the 4430 at the top of the heap even above the S3100, Altec Model 19, Valencia etc. based only on my experience with these speakers. I would be curious to know if you feel your speakers would benefit from the addition of, for lack of a better term, a super tweeter crossed pretty high, say 12K to 15K? May be a difficult question to answer but I never felt the need for it with the 4430 or the 3100. There are some on the forum who would disagree. Maybe their hearing or "trained ears" are better than mine? I would be very interested in your thoughts.:yes:

Mark

3dbdown

05-05-2008, 09:21 PM

Mark............

Thanks for the Kudos, and it truly is a good feeling........

As to your question, I don't really know yet....In the process of playing with EQ, I did do a little tweaking in that range, and my first impression is, that the 2425h handled it pretty well......At least, I think I have 2425H's....I haven't pulled them apart yet.

The JBL documentation says 2426H, but I don't yet know the exact vintage of my cabs. I asked on the serial number thread, but have not gotten a response yet.

This may not be the place to ask, but my serial #'s are 256386 and 256391.

I was a big fan of the 2405's in my Jubals, and it's hard for me to think that they might not add something positive, but then, I have to get more used to the 4430's before I could make a really informed comment on that.

I plan to stay off the EQ as much as possible.....I don't want to wind up using it as tone control.

Besides the possible phase shift issues, a wise old transducer engineer once told me that when you start adding or subtracting too many bands of EQ....It's called volume control!!!

So, I'm only planning it for the room node problem, and using the available tone controls on the Marantz for problems with any program I might be listening to at any given time.

I just know that I really like these babys, and know that no matter what I do in the future, I will not be getting off my 4430's!!

Rick

3dbdown

05-05-2008, 09:28 PM

Mark....

Forgot this.....I'm also a big two-way fan.....Always was at JBL, and still am.

I would trade 3 pairs of Decade 36's for one pair of Decade 26's any day of the week, and twice on Sunday!!

I had a pair on my desk at JBL, and remember many nights at 8, 9, or 10 o'clock.....working on the drawings to get the L212 out on time....That those '26's kept me going !! Wish to God I still had 'em today !!

Rick

BMWCCA

05-05-2008, 09:50 PM

I'm also a big two-way fan.....Always was at JBL, and still am.

I would trade 3 pairs of Decade 36's for one pair of Decade 26's any day of the week, and twice on Sunday!!

I had a pair on my desk at JBL, and remember many nights at 8, 9, or 10 o'clock.....working on the drawings to get the L212 out on time....That those '26's kept me going !! Wish to God I still had 'em today !!That's encouraging! I just bought a pair for $29. They're sitting in a friend's office in SC waiting for me to pass by or find someone going my way from there. I look forward to hearing them.

-Phil
030, L112, L150A, L20T, 4412A, L5 . . . and L26

3dbdown

05-05-2008, 09:57 PM

Don't let 'em get away, Phil !!

Rick

oznob

05-05-2008, 10:12 PM

Thanks for your comments Rick. I have had my share of 3 and 4 ways, including 250ti's but, I always come back to the big horn loaded two ways. I guess I feel that less is more. I have never owned or listened to the venerable 43XX studios which may change my mind but hey, they are out of my price range at this time anyway. All of my current speakers, save for the garage sale L100's, are two ways. My favorite is the 4301B with Zilch's updated crossovers. I can listen to them for hours! The 3100's are keepers and I am confident in their new surroundings they will shine. Of course an Array 1500 sub would sure help!:D
Mark

BMWCCA

05-05-2008, 10:20 PM

Don't let 'em get away, Phil !!No problem. I bought them off Ebay as "local pick-up only" and had a friend pick them up for me. He's checked them out and said they're fine. I'm not scheduled to be in that office until early next year but someone will be headed this way and want to feed my JBL jones before then. Got an $18 Soundcraftsmen DC-2215 EQ the same way a couple of months ago and it's home now.

I figure Heather will probably go antiquing in SC and deliver them to my door! :applaud:

3dbdown

05-16-2008, 03:41 PM

Hi, forum!

Well, I'm getting the period correct systems together, and loving my 4430's. I'm going to pull the networks next week, and replace the caps with something better, Solens, and get rid of the four .01uf bypass caps in the process. I'm told, by reliable authority, that this simple, inexpensive fix will really open the monitors up, including the woofer circuit.

I would like to maybe go the charge-coupled route, but can't locate a schematic/parts list by which to do it......Maybe someone knows???

My most immediate agenda is, however, to locate a receiver with tuner, with pre-amp outs, just two-channel analog, to run the 4430's with. I just want some INEXPENSIVE, but current technology to fire them up.

And so, here is my question: What do you guys think of the Harman Kardon 3385?? They can be picked up for a song on E-bay, refurbished by HK Factory Folks, and can even be gotten new for about $210.

This would certainly not be the end all be all for the 4430 system, but it would be more period correct, as well as free up my Marantz 2325 for restoration, later to be plugged into my Jubals and 4311's for the "Intermediate mid-'70's" system.

My "Old technology" system is the restored Fisher 400 tube receiver, with turntable, plugged into the JBL Alpha 1's....used exclusively for my old vinyls.

So, I'm open to suggestion on the newer technology receiver, and I don't need the power amp section, as I'm quite happy with my QSC's.

Any help or thoughts on the Charge-Coupled route for the N3134's as well as the HK 3385, or alternate choices would be most welcome....

Thanks,

Rick

4313B

05-16-2008, 03:46 PM

Any help or thoughts on the Charge-Coupled route for the N3134's as well as the HK 3385, or alternate choices would be most welcome....I think I posted the cc 4430 network schematic several years ago. I think you might want to go cc with that receiver. I ran 4430's for a time with unbiased Solen's, both non-bypassed and bypassed, and ended up going biased.

***

Yep, I have the cc 3134 network schematic on my HDD but will have to reload AutoCAD to snap a photo of it for posting.

***

First one is full passive, second one is bi-amp only.

Here is a link to a copy of the original schematic at JBL Pro - 3134 (http://www.jblproservice.com/pdf/Network%20Schematics/3134%20Network.pdf)

3dbdown

05-16-2008, 10:35 PM

Thanks so much 4313B......

When you referenced "that receiver", with respect to CC being the better approach, did you mean the HK-3385 or the Marantz 2325?

I notice in the second schematic, the HF is still paralleled to the LF input. You say that's the Bi-amped version, so I would think the input to the HF should be across the 40uf cap and pin 1 of the L-pad. What am I not seeing? Keep in mind, I'm totally unfamiliar with the CC approach!

Also, you talked about "biased". Was that the CC network, or the original passive networks? Although I understand biasing, I am not sure I understand what you mean in this particular context. I wonder if you were talking about using or not using the .01uf bypass caps in the original non-CC networks?

Rick

4313B

05-17-2008, 05:01 AM

When you referenced "that receiver", with respect to CC being the better approach, did you mean the HK-3385 or the Marantz 2325?

HK 3385 or HK 3485

I notice in the second schematic, the HF is still paralleled to the LF input. You say that's the Bi-amped version, so I would think the input to the HF should be across the 40uf cap and pin 1 of the L-pad. What am I not seeing?

Sorry, I never finished the drawing. So here it is finished. It looks nicer before I cut and paste it into Paint Shop Pro and then post it. If I had a MAC it would probably all work perfectly.

Also, you talked about "biased". Was that the CC network, or the original passive networks? Although I understand biasing, I am not sure I understand what you mean in this particular context. I wonder if you were talking about using or not using the .01uf bypass caps in the original non-CC networks?

I tried the networks with Solen capacitors and didn't like the results.
I bypassed the Solen capacitors with the JBL 0.01 uF bypass capacitors and didn't like the results.
I biased the Solen capacitors and liked the results.
"biased" = "cc" = "charge coupled"

Note that the 20 uF of series HF capacitance in the bi-amp only version is part of a 2-pole filter. The second pole is in the 4430/4435 card for the JBL 5234A and 5235 electronic frequency dividing network. Some people argue that using either JBL network negates the benefits of bi-amping and they are probably right because they do sound pretty bad these days. I think a few guys have sufficiently modified them to sound better. One could use a line level high pass instead of an op-amp high pass if one knew the input impedance of the HF amplifier. ;) One might also want to see if they can do without the zobel/conjugate (and 9 V biasing source) across the 2235H in the bi-amp only version.

Chas

05-17-2008, 06:00 AM

Member 4313B has already said it, but I have to reiterate it based on my own experience. If you are going to the trouble of pulling the network boards, etc. non-CC Solens will not be optimal.
Good luck.

mech986

05-17-2008, 10:56 AM

I tried the networks with Solen capacitors and didn't like the results.
I bypassed the Solen capacitors with the JBL 0.01 uF bypass capacitors and didn't like the results.
I biased the Solen capacitors and liked the results.
"biased" = "cc" = "charge coupled"

Note that the 20 uF of series HF capacitance in the bi-amp only version is part of a 2-pole filter. The second pole is in the 4430/4435 card for the JBL 5234A and 5235 electronic frequency dividing network. Some people argue that using either JBL network negates the benefits of bi-amping and they are probably right because they do sound pretty bad these days. I think a few guys have sufficiently modified them to sound better. One could use a line level high pass instead of an op-amp high pass if one knew the input impedance of the HF amplifier. ;) One might also want to see if they can do without the zobel/conjugate (and 9 V biasing source) across the 2235H in the bi-amp only version.

Hi 4313B,

Although I have looked and searched, I don't recall seeing any thread on modding the 5234-5235. Can you suggest anything to bring them to decent standards (5234 uses the first basic opamps u741's ) or are we really better off just getting a more modern design (M53x units or other brands?) to do the biamp/active crossover work?

Bart

Zilch

05-18-2008, 10:50 AM

Several members, including myself, have done 4430 active biamp according to JBL specs using the JBL card in 5235, and gone back to full passive.

Here's the N3134 passive-only charge-coupled (biased) crossover I built, so you can get an idea of what it is as implemented by the Zilchster:

http://audioheritage.org/vbulletin/attachment.php?attachmentid=21501&stc=1&d=1166588174

It's been tweaked a bit to run the different HF system shown.

It's still biampable, but that requires two batteries, ideally, one each for HP and LP....

spkrman57

05-18-2008, 11:25 AM

You said:

"It's still biampable, but that requires two batteries, ideally, one each for HP and LP...."

You should not need 2 batteries for bi-amping as the resistors between the battery and crossover will keep any interaction from happening.

If you see reasons to the contrary, please comment as I am interested in your opinion on this!

Regards, Ron

hjames

05-18-2008, 11:52 AM

Maybe 2 batteries, but - one for each speaker (left and right), not one for each driver!

You said:

"It's still biampable, but that requires two batteries, ideally, one each for HP and LP...."

You should not need 2 batteries for bi-amping as the resistors between the battery and crossover will keep any interaction from happening.

If you see reasons to the contrary, please comment as I am interested in your opinion on this!

Regards, Ron

Zilch

05-18-2008, 12:43 PM

Maybe 2 batteries, but - one for each speaker (left and right), not one for each driver!Nope, one for each driver/filter. Look again at 4313B's schematics to apppreciate the need for two batteries. There are two in the biamp implementation.

Why is that? Because, with a single battery, it's (-) connection must be common to both filters and amplifiers.

If you are biamping using one amp per channel, (I forget if that's "horizontal" or "vertical,") that may not be an issue, if it's permissible to common the output "grounds," but, using separate amps for HF and LF, particularly different types, it's asking for trouble.... :yes:

spkrman57

05-18-2008, 12:55 PM

That was a situation that I did not anticipate.

Regards, Ron

3dbdown

05-18-2008, 02:34 PM

Zilch, are you saying that if I Bi-amp though my QSC's, that I should do the Low and Hi-freq out of amp "A", for left channel, and the Low and Hi-freq out of amp "B" for my right channel, as opposed to Low-freq left and right ought of amp "A", and Hi-freq out of amp "B" for both channels ??.....
And, if so, why?

Also, thanks for the pix of the biased 3134's.....Are those Solens, or Clarity SA's in the photo??

Waiting with baited breath,

Rick

Zilch

05-18-2008, 04:54 PM

They are Solens. Big caps are 24, 16, 12. 16 + 12 = 28.

I do not typically use one amp on each channel, rather, a smaller amp for the HF of both channels.

3dbdown

05-19-2008, 12:48 AM

Zilch.......

Yeah, that's what I thought.......must have been too much Sun around here today!! Comfortijng to know I won't have to re-wire my system!!

I am getting ready to order the Solens for my first step in tweaking the 4430's, but the CC version will be Phase 2. I need to start out with a reference point, so am just going to change the 30 year old caps for now, and give it a listen. It's just that my number 1 rule has always been: Does this sound good to me? This process can be so very subjective, and I've never found a better approach.

I spent all day Saturday going through the threads on CC. After 4313B posted the schematics, I reasoned that I really, after all, should do my homework, instead of asking for a lot of info that's already been posted. It was very nice of him to do that for me though. The research really helped me to catch up on technology, and to learn why you guys do these things, and what you do and do not like about certain mods. A real treasure of quality info! Not to mention quite a trip through the looking glass, Alice!!

I suspect that if I do not like the straight cap change, I will not bother to add the bypass caps. I will, rather, proceed with building the CC's. Didn't seem to be much support for the bypassed version, and I am thinking perhaps the Solens will not need it or benefit from it.

I think I will try to configure the CC version external to the cabinets, rather than inside. Seems easier to peak and tweak, and keeps me from opening the cabinets too often if I decide to try different things.

I was curious as to your inductors, as far as which ones you are using. Are they a PartsExpress line, or what? Also, your L-pad plate looks like the PartsExpress one, but I was unable to locate the 30 ohm rheostat. Any thoughts?

Rick

3dbdown

05-19-2008, 12:55 AM

Also, I think I will stay with passive, but I did have a question for 4313B.

You mentioned that the other pole of the 2-pole filter was in the 5235, which I do not have. How does that square with my dbx 223 crossover, if I do decide to try the bi-amp version?
Thanks,
Rick

Zilch

05-19-2008, 01:15 AM

I was curious as to your inductors, as far as which ones you are using. Are they a PartsExpress line, or what? Also, your L-pad plate looks like the PartsExpress one, but I was unable to locate the 30 ohm rheostat. Any thoughts?It's all Parts Express. I use terminals 3 and 2 of an L-pad, i.e., 0 - 8 Ohms, for the rheostat, as I found from experience that the HF always adjusts to the very lowest portion of the 30 Ohms. You can simply put a fixed resistor in series to move the adjustable range.

Alternatively, you can use terminals 1 and 2 to cover the stock range, but the control operates backwards, providing max attenuation fully clockwise....

berga12

05-08-2017, 05:41 AM

Hi,
if I'm using 2420 16ohm instead of 8ohm version, should I double "L" and divide by 2 "C" value in the HF session right? for a first trial...?

Earl K

05-08-2017, 06:41 AM

Hi,
if I'm using 2420 16ohm instead of 8ohm version, should I double "L" and divide by 2 "C" value in the HF session right? for a first trial...?

The 2420 was only available in one impedance & that was ( officially called ) 16 ohms .

http://jbl.francis-blake.com/ebay/2420/3.jpg

Here's an actual impedance measurement of the le85 ( which is the consumer version of the 2420 >> this was measured by Zilch, I believe ) ;

http://audioheritage.csdco.com/vbulletin/attachment.php?attachmentid=9682&stc=1&d=1124845134

You can see that AC impedance is a frequency dependent, moving target ( since it's actually a curve > specifically in the area where LC components to their work ).

Putting an 8-ohm Lpad right before the driver ( & dialing in a few db of attenuation ) will knock the working impedance of the HF circuit down to an almost ( flat-line ) 8 ohm load .

:)

berga12

05-08-2017, 07:20 AM

So,looking at the curve means I can use at 1000hz the standard 4430 crossover with the 8ohm Lpad....:bouncy:

grumpy

05-08-2017, 07:24 AM

berga12

05-08-2017, 07:39 AM

Understood

maybe a slight adjustment on the Crossover is needed, even if i'm also thinking on a "passive" bi-amp, let see, it's just for fun!

I've 2420....so I need to use them, is a Beryllium diaph existing?

grumpy

05-08-2017, 07:51 AM

no Be in that format that I'm aware of.

I'd (personally) go with the Al unit I mentioned already, unless you like to regularly stress the system loudness capability (then Aquaplassed Ti, but that again is DIY or commissioned).

Earl K

05-08-2017, 07:54 AM

Ultimately, I would think you would want an 8-ohm diaphragm (D8R2421 or perhaps a dusted Ti version),
as I believe the system was already limited in the level matching between drivers given the HF EQ required <<SNIP>>

Usually I'd agree Grumpy, but it's worth noting that Zilch showed ( more than a couple of times ) that a healthy diaphragmed le85 ( & I accept that most 2420's are likely not that healthy being a "PRO" device ) can out-perform the equivalent ferrite magnet type driver ( ie; 2425/6J ) above 3K .

7690576906

Seems to me ( from the above traces ), that above 10K, the le85 ( maybe 2420 ) has 3db extra UHF to play with ( which ought to negate the gain advantage of using the lower impedance [ "H" version ] driver ).

:) ( just speculating )

badman

05-08-2017, 09:45 AM

Nope, one for each driver/filter. Look again at 4313B's schematics to apppreciate the need for two batteries. There are two in the biamp implementation.

Why is that? Because, with a single battery, it's (-) connection must be common to both filters and amplifiers.

If you are biamping using one amp per channel, (I forget if that's "horizontal" or "vertical,") that may not be an issue, if it's permissible to common the output "grounds," but, using separate amps for HF and LF, particularly different types, it's asking for trouble.... :yes:

Miss you buddy. An alternative solution to our departed brother's is to use half the resistor value on both + and -, and use individual resistors per connection point. Since the R values are high, you'll be able to use the same battery across multiple filters without worries of crosstalk or amplifier loading.