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Biamping ADS L1230s?

KFCrosby said:
That is a good looking speaker/room interface ya got there
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Damn straight, that's freakin' sweet! (Tends to confirm why I like the L1230 over any other speaker ADS made from that era too.) It is also good to see the high-Q peak gone which is likely active crossover interaction. OP, you might want to try your biamp set-up again with these changes -

No auto-correction EQ or any boost, just HP function only

Lower HP point (adjust between 300-400Hz), whichever gives the best result

Measure

Reverse polarity of amp/speaker leads driving MF/HF section on the L1230's

Measure again

You'll need to fiddle with crossover point & phase coupled with listening at low/moderate level and measurement to dial them in. The above doesn't seem like much but it is a good couple hours on a weekend afternoon. You should end up with something very close to your 'no EQ' RTA image above. Then you can manually adjust the bass level to where it sounds and/or measures best. This is where I would be the most interested in your comments as to how the system sounds so configured.

The only other improvement that you could do to the L1230's is to provide a steep HP to the woofers themselves and add a subwoofer if the low bass drop-off is too much. Your room is helping you (or as much as the RTA can be believed) so you might not even notice that you have HP on the woofers. I would probably try various HP points from 40-65Hz if you ever get any woofer bottoming. This would be totally dependent upon how you listen to them though. If you run them hard on dynamic material such as orchestral or use them for home theater, it could prevent mechanical issues and potential woofer failure. This is the one weak spot on the L1230's.
 
Just FYI

I settled on 1 500hz x-over point for my 1530's. Started at 400, went to 440 and finally bumped to 500. Seemed to be the sweet spot for my setup.

(just for trivia 500 is damn near the note B (493.883 hz) over standard A or A440)
 
Kevin/Soundmotor,

Thanks for the advice. Gives me something to play with this weekend.

Kevin, I grew up in Corinth, MS, about 90 miles east of Memphis. Memphis was the big city we went to as kids for concerts (Midsouth Coliseum) and other assorted mayhem. :D

Regards, BmWr75
 
I know Corinth well. The Midsouth Coliseum is still there, but is in a state of disrepair that you wouldn't believe. The Memphis Pyramid was supposed to replace it, but the sound in there was horrible. It is now standing empty in favor of the new Memphis Grizzlies FedEx Fourm. I've been here for 21 years now and have seen a lot of changes, some good, some not so, but never have I seen major venues discarded the way these tow building have. The Coliseum was a great place for concerts and other events.

The Memphis in May Festival will be here before you know it and it always kicks off with the Beale Street Music Festival (otherwise know as Memphis in Mud)

BSMF01.jpg
 
Never been to the Pyramid. Lived in Little Rock for 20 years after leaving Corinth and passed it many times headed back to Corinth to visit the folks. Remember when it was new, the reflection off it in the afternoon was blinding when entering Memphis across the new bridge.
 
soundmotor said:
Damn straight, that's freakin' sweet! (Tends to confirm why I like the L1230 over any other speaker ADS made from that era too.) It is also good to see the high-Q peak gone which is likely active crossover interaction. OP, you might want to try your biamp set-up again with these changes -

No auto-correction EQ or any boost, just HP function only

Lower HP point (adjust between 300-400Hz), whichever gives the best result

Measure

Reverse polarity of amp/speaker leads driving MF/HF section on the L1230's

Measure again

You'll need to fiddle with crossover point & phase coupled with listening at low/moderate level and measurement to dial them in. The above doesn't seem like much but it is a good couple hours on a weekend afternoon. You should end up with something very close to your 'no EQ' RTA image above. Then you can manually adjust the bass level to where it sounds and/or measures best. This is where I would be the most interested in your comments as to how the system sounds so configured.

The only other improvement that you could do to the L1230's is to provide a steep HP to the woofers themselves and add a subwoofer if the low bass drop-off is too much. Your room is helping you (or as much as the RTA can be believed) so you might not even notice that you have HP on the woofers. I would probably try various HP points from 40-65Hz if you ever get any woofer bottoming. This would be totally dependent upon how you listen to them though. If you run them hard on dynamic material such as orchestral or use them for home theater, it could prevent mechanical issues and potential woofer failure. This is the one weak spot on the L1230's.
Click to expand...

Soundmotor,

Did the suggested experiment, see attached results. No EQ, woofer phase inverted versus not. Ended up with flatest curve at xover point of 600 Hz on the Behringer CX-3400.

Main thing I noticed is inverting the woofer phase got rid of the huge dip at the crossover point.

Have not hooked up a woofer yet. But, the CX-3400 does allow for that if I decide to hook up a woofer.

FYI, these measurements were taken with a Behringer ECM8000 mic and DEQ2496. Zilch tells me to always take the measurements on axis with the tweeters at 1 meter. Since the tweeter/midrange on these speakers is at a 45 degree angle from the woofers, I placed the mic at a perpendicular to the woofer plane and aimed at the place on the speakers where the 45 degree angle occurs. So, am not aimed straight at (e.g., perpendicular to) the tweeter/midrange, instead am off axis by ~45 degrees.

Regards, BmWr75
 
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Don't know where the phase inversion issue is coming from, but that notch at 500 hz is what AutoEQ was initially trying to "fix." You could invert either the LF or HF with a push of the "Inv" button on the CX3400 for that section, i.e., swapping the amp output leads is unnecessary.

I try to use the 10 dB/major division scale for posting, i.e., 30 dB full scale.

Your deliciously flat curves @ #19, above, were done at half that resolution and, well, "deceptive."

Todd often posts at 5 dB/division, max resolution for DEQ2496, which I find difficult to read, as it reveals detail which I generally regard to be irrelevant. :dunno:

[This is all enormously good speakergeek FUN...! :banana: ]
 
BmWr75 said:
FYI, these measurements were taken with a Behringer ECM8000 mic and DEQ2496. Zilch tells me to always take the measurements on axis with the tweeters at 1 meter. Since the tweeter/midrange on these speakers is at a 45 degree angle from the woofers, I placed the mic at a perpendicular to the woofer plane and aimed at the place on the speakers where the 45 degree angle occurs. So, am not aimed straight at (e.g., perpendicular to) the tweeter/midrange, instead am off axis by ~45 degrees.

Regards, BmWr75
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I'd be interested to see what the measurement looks like on-axis with the tweeters as Zilch suggested rather than on the fold. In other words, approximating the listening position. You could not listen to them as miked unless you were way off-axis to one and directly in front of the other. May not show anything substantial or it might, dunno. Does this make sense?
 
Here's the on-axis with tweeter/midrange measurement. The on-axis measurement resulted in a bigger LF peak and less flat response curve overall. The off-axis measurement in the prior post resulted in a +/- 5dB curve. The on-axis measurement resulted in a +/- 7.5 dB curve. Also, I had to turn the tweeter/mid level down a couple of notches to flatten out the response curve. Just goes to show how sensitive RTA is to measurement technique.
 
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Hmmmm.

I've been following this thread with some interest as I just copped a pair of minty ADS L1230's. I read the manual and was wondering what, if any, improvement would flow from biamping an already great sounding pair of speakers. I've got a ST-70 and a pair of Mark IV's. Sounds like the level of complexity may exceed any increase in audible improvement. Of course, I am still missing an important piece, a decent xover so it is really moot. :scratch2:
 
BmWr75 said:
Here's the on-axis with tweeter/midrange measurement. The on-axis measurement resulted in a bigger LF peak and less flat response curve overall. The off-axis measurement in the prior post resulted in a +/- 5dB curve. The on-axis measurement resulted in a +/- 7.5 dB curve. Also, I had to turn the tweeter/mid level down a couple of notches to flatten out the response curve. Just goes to show how sensitive RTA is to measurement technique.
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As we discussed, you should ignore the peak at 40 - 50 Hz, as it is a room mode you're seeing. Those frequencies are omnidirectional, and the axis is largely irrelevant.

You must do a nearfield low-frequency measurement to know accurately what's going on down there.... :yes:
 
BmWr75 said:
.....I was able to successfully bi-amp the L1230s today using a Behringer CX-3400 active crossover feeding two amps....

The biamp set up sounds great to me, but honestly so did the single amp set up with these speakers using two 120 watt tube monoblocks.
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I hope it's okay to revive such an old thread, but I picked up a pair of L1230s recently and would like to try bi-amping as well. Since the original C-2000 is very rare, I've been looking for alternative crossovers and found this thread.

The Behringer CX-3400 seems like an economical option, and I was just wondering if you continued to use it after this tread died in '09? Did you ever have any problems with it? The original ADS C-2000 bi-amp system had a 12dB slope and the CX-3400 is 24dB. Is that okay?

Thanks very much.
 
Curious as well. I regularly check fleabay for the C2000. They come up about once a quarter and go for $500-$1000. One was listed last week and went for over $700. :nono:
 
arossphoto said:
I hope it's okay to revive such an old thread, but I picked up a pair of L1230s recently and would like to try bi-amping as well. Since the original C-2000 is very rare, I've been looking for alternative crossovers and found this thread.

The Behringer CX-3400 seems like an economical option, and I was just wondering if you continued to use it after this tread died in '09? Did you ever have any problems with it? The original ADS C-2000 bi-amp system had a 12dB slope and the CX-3400 is 24dB. Is that okay?

Thanks very much.
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I was just playing around back in 2009 and learning about biamping. Never had any problems that I can recall while using the CX-3400 though. Am not sure the external crossover is even needed to biamp these speakers if you have two amps with the same power rating. Or at least a HF amp with a volume control.
 
jdurbin1 said:
Over $800 actually...
John
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I was watching that one too, and was tempted to put in a bid, but it just seemed too expensive. Especially considering the parts in it are about 30 years old and of unknown condition.

If I'm going to spend that much money I'd be more inclined to buy a new crossover from Marchand Electronics Inc. They're about $1000 and would be custom made for my needs. I emailed Phil Marchand and he said the XM44-2AA with a 12dB/octave, 550Hz crossover module and Linkwitz-Riley alignment would be perfect. He said he could even supply frequency modules for bass boost and/or subsonic filter, just like the C2000.
 
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BmWr75 said:
I Am not sure the external crossover is even needed to biamp these speakers if you have two amps with the same power rating. Or at least a HF amp with a volume control.
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I'm fairly certain that it is. There is a switch on the back of each speaker for normal or bi-amp. In bi-amp mode a portion of the internal crossover is bypassed. In normal mode the one set of terminals is not active.
 
virii01 said:
I'm fairly certain that it is. There is a switch on the back of each speaker for normal or bi-amp. In bi-amp mode a portion of the internal crossover is bypassed. In normal mode the one set of terminals is not active.
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I'm pretty sure you need an active crossover to bi-amp these speakers as well. The switch on the back removes the woofers from the internal xover network, while the 4000Hz crossover point between the mids and highs remains internal to the speakers.
 
I'd have to go back and read the owner's manual to see. Pretty sure it is available as a free download at HiFiEngines.com
 
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