Looky What I just got - 4341 Monitors

[hjames]

Heather, Bo, was it the Low Pass or the High Pass that had to be switched? just want to clarify. Thanks!

Quote Ian...The thing to remember (and I sent an email to Rich about this ) is you must reverse the polarity of the high pass amp outputs going into the 4345 when you use LR 24 db slopes.

Well, I flipped polarity on the low split output thats feeds my 15s and it sounded fine. (note the banana plus are in clear vinyl tubing for insulation). If you are talking about a strictly 2 channel system it shouldn't matter - as long as you have inverted polarity between the woofer with reference to the mid driver. But - in my room, its part of a multi-channel system, so I guess I need to go back and correct the woofer polarity, and invert the hi-split signal. Then check to see how it plays with everything else when playing movies in 5.1 mode.

Sounded great with music (2 ch, no subs) and for tonight's movie (Zefferelli's 1968 Romeo and Juliet - basically mono)

[Krunchy]

I was referring to a 2 channel system, I guess once you get into a 5 channel set up it probably gets a little trickier.
Like you I was very happy with the resulting sounds eminating from the speakers, kinda tough to go back to the old cross over after this.
Thank you Heather! Enjoy the movie.

[hjames]

Yeah, my system is evil (grin) ... I do double duty with it. Got a Harman Kardon receiver last year that I pretty much use as a preamp with remote control. Its can do 7.1 but I only use it in 5.1 mode for films and TV. Its got preamp level outs for all channels, but I just use the receiver's internal amps for Center and the 2 rear surrounds (again, TV and DVDs only). For CDs and vinyl the system is in standard 2 channel mode. Receiver's preamp outs for Front L & Front R feed into the crossover, then into power amps that feed the lo and hi side of the 4341s.

Piece of cake


The movie was great - this year is its 40th anniversary! Our Junior high school English class went on a field trip to see it when it first out. Hadn't seen it since. A real classic, still! (Netflix)

I was referring to a 2 channel system, I guess once you get into a 5 channel set up it probably gets a little trickier.
Like you I was very happy with the resulting sounds eminating from the speakers, kinda tough to go back to the old cross over after this.
Thank you Heather! Enjoy the movie.

[boputnam]

Heather, Bo, was it the Low Pass or the High Pass that had to be switched? just want to clarify. Thanks!...

Ian made a point about imposing the Linkwitz-Riley -24dB slope on the 43-series stock system, wrt the low-pass. I have not "tested" (measured) his point, but empircally it would seem valid.

Both the stock passive network and the active 5234a are -12dB slopes. Using an Ashly with it's -24dB L-R slopes should alone require a 180° shift in phase to maintain the JBL design polarity between the woof and the other tranducers.

[hjames]

Both the stock passive network and the active 5234a are -12dB slopes. Using an Ashly with it's -24dB L-R slopes should alone require a 180° shift in phase to maintain the JBL design polarity between the woof and the other tranducers.

But which amp output needs to be flipped - Low split or high split??

Or does this mean its finally time to find some gear (or find someone WITH gear) and sweep the system (!!?)

[Krunchy]

Or does this mean its finally time to find some gear (or find someone WITH gear) and sweep the system (!!?)

I like that idea better Heather

Thank you Bo! I myself flipped the high pass, and it seemed like there was a noticeable improvement in the sound, the lows & mids seemed more in sync & just generally sounded better. If one was not imposing the L.R. Slope this step of flipping/reversing the polarity would not be necessary? I also had the polarity reversed when I was playing with it yesterday and went into the Butterworth side and it also sounded quite nice, am I treading on thin ice here. The L.R. set up seemed to produce a bit more of a "rounded off" type of sound for me, whereas the Butterworth seemed a little brighter, very nice still. Both settings were very pleasing & neither setting produced any of the harsh/shrill tones I was getting on some recordings with the 5235.
Still had plenty of room to play with on the LF & HF outputs.
Its a great little unit Bo, Thanks again.

[Chas]

But which amp output needs to be flipped - Low split or high split??

Either one. Unless you are concerned about absolute polarity.

http://www.positive-feedback.com/Iss...woodeffect.htm

[boputnam]

But which amp output needs to be flipped - Low split or high split??

But, I thought you had already done that...?

...I did flip the polarity of the bass amp output (JBL 6260) as recommended in that thread. ...The bass is definately firmer

No?

Heather, Bo, was it the Low Pass or the High Pass that had to be switched? just want to clarify. Thanks!

Chas has it...

Either one. Unless you are concerned about absolute polarity.

Although I suppose in the case of the 43xx series, you'd do better to reverse the LF, since those woofers are working "backwards" afterall...

[Krunchy]

Thanks again Bo!.

Interesting article there Chas, thank you. I guess absolute polarity is not the goal here. That being said and not to beat a dead horse, I did reverse the polarity of the Low pass amp (after returning the High Pass to non-reversed polarity), did this back and forth a couple of times in fact. I would be hard pressed to tell you wether there was a noticeable difference in lows & highs in either scenario, they both sounded good. But, reversing one or the other was infinitely better then not reversing the polarity of either amp at all And based on Bo's last post will opt for a reversed LF, who wants to be backwards...all the time

Quote from article...
The best way to teach yourself—is to reverse all four (or eight) speaker wires, tediously back and forth, to learn the condition, then play it from there. Your rewards will more than compensate the effort, believe me! Remember, no one ever promised you that audio would be easy.

[Ian Mackenzie]

Yeah well as I have said many times before this who phase thingy is very easy to screw up.

One point is that the 4343 active filter is different to the 4345 (as is the mid cone driver).

Specifically the 4343 active filter has -3 points spread butterworth 12 db filters at approximately 230 (Low pass) and 300 hertz (high pass) and each slope is -6 down at 300 and 230 hertz respectively. The woofer and mid are wired out of phase. JBL sorted this after measuring the actual acoustic output under controlled conditions.

The actual acoustic summation at the crossover point will depend on a bunch of physical and electro-accoustic factors common to the particular design. The location of your enclosures and your relative listening position will also have an effect. For example, the 4343 was often suspended or sofit mounted in the recording environment, not stuck on the lounge room floor in the corner.

If you are to use other active crossovers plan on doing some knob fiddling and have a nice analyser thingy handy and lots of time up your sleeve.

All said and done the Ashly is a blessing for those who want to play.

[spwal]

my marchand arrived -- not working need to send back to phil. in the meantime, couldnt stand the 6 month wait anymore and picked up this BBE thing from guitar center. hey it works, and i get to play around with levels and such.

system is finally working, since i embarked on the biamp journey 6 months ago as many of you know. still need a hefty low-end amp.

pics and story to follow when everything is set up for real.

[hjames]

Saw an Ad on ebay for an ACE-515 Adcom AC Enhancer - mumbo-jumbo name, but the description grabbed me ...
"This device is an AC expander/delay system for your audiophile equipment. There are 7 outlets on the rear panel. 4 of the outlets are labeled accessories and are switched with a 30 second delay on turn off. 2 of the outlets are labeled amplifiers and are switched with a 10 second delay on turn on. The other is an unswitched outlet. There is a heavy duty AC cord extruding from the rear panel for the main AC supply. THis gets plugged into the power mains. The other lighter duty AC line gets plugged into a switched outlet or similar to send a control signal to the entire unit. When you switch on your preamp it sends a signal out thru the ac line to this device to power on all of your other components. There is a switch on the front panel for main on and off. There are also 2 LED indicators on the fron panel for amplifiers and accessories. "

Okay, basically this thing has a "sensing" power cord that plugs in the switched outlet on my receiver, so when I power up the receiver (via remote), the Adcom power on my accessories (the Ashley crossover), then 10 seconds later power up the two JBL/UREI power amps. No thump!

When I power down the receiver, the Adcom powers down the 2 power amps, then, 30 seconds later, powers down the Ashley - no thump!

The ONLY problem is that its taller than the vent panels I had so had to pull the vent panels and tighten up the spacing to fit the Adcom in over the Ashley. Plus the Adcom is lacking rack mount ears ... (just $44 from the retailer!)

Fortunately the rack has never run hot, but nevertheless, I want to get a taller set of rack-rails and rebuild the minirack to get the spacing back where it was.

Yeah, my system is evil (grin) ... I do double duty with it. Got a Harman Kardon receiver last year that I pretty much use as a preamp with remote control. Its can do 7.1 but I only use it in 5.1 mode for films and TV. Its got preamp level outs for all channels, but I just use the receiver's internal amps for Center and the 2 rear surrounds (again, TV and DVDs only). For CDs and vinyl the system is in standard 2 channel mode. Receiver's preamp outs for Front L & Front R feed into the crossover, then into power amps that feed the lo and hi side of the 4341s.

Piece of cake

[johnaec]

Nice! 'Looks like you got it at a great deal, too! 'May look into one or two myself...

I've got some other Adcom stuff I also really like, including a pre-amp and a 6-speaker selector switch, which has really come in handy with all the different combinations I like trying.

John

[hjames]

Nice! 'Looks like you got it at a great deal, too! 'May look into one or two myself...

I've got some other Adcom stuff I also really like, including a pre-amp and a 6-speaker selector switch, which has really come in handy with all the different combinations I like trying.

John

Well, the problem of adding to my rack means I have to rebuild the rack. Adding the Adcom control unit pushed it beyond its capacity. But I ought to have spacing between the poweramps, and I want the vent panels back in place ...

So, its time to rebuild it! This time, I want some expansion capability ...
Its all about the rack-rails - so, I tried GuitarCenter, but all they had was the 14 inch rails - too short! - thats what I used LAST time. So, I checked ebay and found a vendor, dbLittle, who had lots of rails for sale. I settled on 16U rails (28 in tall) for around $26 shipped.
I figure 28 inch rails in a 32 inch space would leave open space at the top for better airflow and cooling.
The amps have never run hot, but - it can't hurt.

I liked the sides of the old unit, and had some 32 inch tall beech veneer panels from an old shelf unit I could repurpose. I figured I could buy a 24x24 inch square of 3/4 plywood from HomeDespot and with some basic cutting, even a thumbo like me could make a open basic box for a tasteful audio rack!

So last night I fired up the tablesaw and cut it down to 24x 19, then cut that into 4 6in wide "planks" for a semi open top and base for better airflow.
Drilled through the side and screwed the planks in place, then some rubber feet on the bottom. Then screwed the black rails into place ...

Voila!

'course the hard part is taking apart the old rack and pulling the gear, then putting it all back into place in the new rack - maybe I'll get to that over the weekend! I add more pix Sunday when its loaded ...

[Fred Sanford]

Well, the problem of adding to my rack means I have to rebuild the rack. Adding the Adcom control unit pushed it beyond its capacity. But I ought to have spacing between the poweramps, and I want the vent panels back in place ...

So, its time to rebuild it! This time, I want some expansion capability ...
Its all about the rack-rails - so, I tried GuitarCenter, but all they had was the 14 inch rails - too short! - thats what I used LAST time. So, I checked ebay and found a vendor, dbLittle, who had lots of rails for sale. I settled on 16U rails (28 in tall) for around $26 shipped.
I figure 28 inch rails in a 32 inch space would leave open space at the top for better airflow and cooling.
The amps have never run hot, but - it can't hurt.

I liked the sides of the old unit, and had some 32 inch tall beech veneer panels from an old shelf unit I could repurpose. I figured I could buy a 24x24 inch square of 3/4 plywood from HomeDespot and with some basic cutting, even a thumbo like me could make a open basic box for a tasteful audio rack!

So last night I fired up the tablesaw and cut it down to 24x 19, then cut that into 4 6in wide "planks" for a semi open top and base for better airflow.
Drilled through the side and screwed the planks in place, then some rubber feet on the bottom. Then screwed the black rails into place ...

Voila!

'course the hard part is taking apart the old rack and pulling the gear, then putting it all back into place in the new rack - maybe I'll get to that over the weekend! I add more pix Sunday when its loaded ...

Nice work! You can re-use your shorter rack rails in the rear- to support deeper gear that reaches the back, reverse-facing shallow gear you don't need to see/access, lacing bars, or even just some panels for some squaring/bracing.

Give a call for brainstorming if you like. Sorry I've been busy with visitors, did you ever work out the slight hum you were hearing with the Adcom piece?

je