Bi-amping 4343's

[JBL Dog]

I finally got around to bi-amping the 4343's. WOW! Night and day compared to passive. I'm using JBL 6290 and 6230 amps for power and a JBL 5234A crossover along with factory 4343 cards. Those JBL's are much cleaner sounding than the McIntosh MC7270 I was using (go figure?).

If you own 4343's, bi-amp them. You won't be disappointed!

[RKLee]

Biamping/active crossover, ie using 1 amp per driver will effectively double the amplifier power. Plus any distortions produced by the amplifier driving the LF drivers won't appear in the HF driver(s). The problem with passive crossovers, is that the amplifier sees the various inductors and can't apply full damping to the drivers; whereas in active crossovers, the amplifier is connected directly to the drivers therefore will see the direct damping of the amplifiers. The difference to me is night and day. I am paraphrasing this from an old Altec brochure on this subject for justifying active crossovers.

I couldn't believe how clear the sound was when using an active crossover.

[JBLOG]

JBL Dog,

Wow, The JBL sounded cleaner than the Mac in the biamp mode!
Maybe a big part of the difference you are hearing in due to differences in the ability of the amp to control the driver(s).
I was was surprized to find that the MC 7270 has a damping factor of only 30 while the JBL 6200 series is 200.

http://www.jblpro.com/pub/obsolete/6200ser.pdf
http://www.roger-russell.com/amplif2.htm#mc7270

NuForce amps chime in at 4000!

[RKLee]

JBL Dog,
.
.
I was was surprized to find that the MC 7270 has a damping factor of only 30 while the JBL 6200 series is 200.

http://www.jblpro.com/pub/obsolete/6200ser.pdf
http://www.roger-russell.com/amplif2.htm#mc7270

NuForce amps chime in at 4000!

Not too familiar with the Mac amps(they are just way too expensive), but I think the tube ones are pretty low on the damping factor, and also their solid state amps were pretty low also because they used a coupling output transformer in the output stage. Most modern amps don't have transformers in the output stage which is why the JBLs amps are so high.

Bottom line is that you will notice a quantum jump in clarity by taking the trouble to use an active rather passive crossover.

You can also get steeper slopes at crossover. In the typical passive crossover, you can only have 12dB/octave slopes, where with active crossover, in addition to 12, 18, and even 24dB/octave are available. I would told that odd order slope of 18 is the best to get rid of various odd-order distortions.

[timc]

JBL Dog,

Wow, The JBL sounded cleaner than the Mac in the biamp mode!
Maybe a big part of the difference you are hearing in due to differences in the ability of the amp to control the driver(s).
I was was surprized to find that the MC 7270 has a damping factor of only 30 while the JBL 6200 series is 200.

http://www.jblpro.com/pub/obsolete/6200ser.pdf
http://www.roger-russell.com/amplif2.htm#mc7270

NuForce amps chime in at 4000!

Hi.

The factor of 4000 is only in the lower octaves. The number in itself isnt too important. The thing to look for is how well the damping factor holds when moving up the Freq. range.

I tried a amplifier (much like NuForce) with a damping factor of 1000 in the bass region. My amplifier at the time, a McIntosh MC402, had way more controll.

The damping factor of the Class-D amplifier dropped like a stone above a few hundred Hz. Mc rated the damping factor of the 402 to >40. This means it never drops below 40. The Class-D thing surely did. I found measurements on a similar amp on the web and at higher Freq. the damping factor went almost to zero.

I believe it was QSC or LabGruppen who wrote a paper on the subject of damping factor. The stated that the most important thing was not to have the biggest number but the most even number uppwards in Freq.

-Tim

[nrwjbl]

..... If you own 4343's, bi-amp them. You won't be disappointed ...!

I had same experience when I got my 4343's biamped. First tried with crossover Urei 5235 and now I run them with JBL Synthesis SPP-AC1.
Amping I do with Lexicon LX-7- amp.
Bass response is much better and powerful, mids and highs crisp and clear. It paid to do so. Sounds really JBL ...!

Biamping my 4435's was not that successful so I returned to passive mode.

peter

[JBL 4645]

I finally got around to bi-amping the 4343's. WOW! Night and day compared to passive. I'm using JBL 6290 and 6230 amps for power and a JBL 5234A crossover along with factory 4343 cards. Those JBL's are much cleaner sounding than the McIntosh MC7270 I was using (go figure?).

If you own 4343's, bi-amp them. You won't be disappointed!

JBL Dog

Well now that you’re pleased with the active crossover which is so choice can we see some pictures please lots of pictures!



Found a link to other JBL 4343 under Google image so many enjoy.

http://images.google.co.uk/images?svnum=10&um=1&hl=en&q=JBL+4343+&btnG=Search +Images

[gerard]

Jbl dog

which Crossover do you use .
JBL original ?
Home made ?


Gerard

[Titanium Dome]

Biamping my 4435's was not that successful so I returned to passive mode.

peter

Several members have commented on little success in the attempt to biamp the 4430 and 4435.

[Zilch]

Several members have commented on little success in the attempt to biamp the 4430 and 4435.

It worked when I did it, just no big whoop, is all, so not worth all the gear and effort. :dont-know

[hjames]

I finally got around to bi-amping the 4343's. WOW! Night and day compared to passive. I'm using JBL 6290 and 6230 amps for power and a JBL 5234A crossover along with factory 4343 cards. Those JBL's are much cleaner sounding than the McIntosh MC7270 I was using (go figure?).

If you own 4343's, bi-amp them. You won't be disappointed!

Any of the big 4-ways will benefit from biAmping - made a world of difference in mine (4341), and I've heard folks with the big'uns 4345s say the same thing.
With mine I use a JBL 552 to dial in the lo/hi split, and run the 6230 and 6260 JBL amps.

[Titanium Dome]

It worked when I did it, just no big whoop, is all, so not worth all the gear and effort. :dont-know

If the intended result is a notable improvement in sound, then it doesn't matter if it "works," it's still "little success."

[blackwell]

Several members have commented on little success in the attempt to biamp the 4430 and 4435.

I wonder if this is because people are bypassing parts in the passive crossover that provide EQ'ing for driver correction? I know they padded down the horn but I suspect that there is probably a litte freq. resp. tailoring in there as well. If you just biamp and don't smooth out the response the way the passive did, then it will never sound right. Just a thought?

[Ian Mackenzie]

There is a specific card used for the 4430/35 in the JBL 5235 active crossover.

The prevailing series capacitor in the 3134/35 networks offered protection for the driver and adds a pole for the final high pass filter. The post passive crossover EQ is always in circuit.

I would suggest anyone considering biamping consider the following:

Re build the crossovers with charge couple topology or use high quality capacitors like Hovlands.

Get the titanium diaphragm dusted or use a Tad driver and get the crossover tweaked for the Tad impediance plot.

Use a Bryston10B active crossover or similar setup for the system

A high quality power amp for the HF driver.

Ian

[Zilch]

I wonder if this is because people are bypassing parts in the passive crossover that provide EQ'ing for driver correction?

Not the Zilchster, no:

http://audioheritage.org/vbulletin/s...ead.php?t=9901

And not a bunch of others who have tried it, either....