my classic system needs advice

mwebb

Member
Hello, I am putting together a system in my basement. Currently running the Optonica sa 5605 with luxman dx 111cd and an ADC equalizer, speakers are jbl 4311b studio monitors with a brand new (1982 new in boxes, my best ebay find yet!) pair of 4312C studio monitors underneath. Need to know how to properly "stack" these speakers in terms of wiring them. Should I add a Sub?
Should I go with separate components (NAD or such?) instead of the optonica? Plenty of power there, I have had it hot enough to turn itself off with auto protect. Sound is crystal clear up to a point then bass begins to flutter etc.

So basically, am I wasting the potential of these speakers? Yes, for sure,
My other options are sae A502, P102 I thought this would be way too much power though.

thx,
 
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First off, a caution: those 4311 woofers (123A3) and 4312 woofers (2213H), tend to be LOW impedence. Where a normal "8 ohm" woofer would generally have a DC resistance of like, 5 to 6-something ohms, these drivers have a DCR of about 4.5 ohms. They actually act more like a 6 ohm woofer, than an 8 ohm... so a pair, is more like 3 ohms when paralleled! This may well be what causes the problem you mention, with the bass fluttering.

One potential solution, obviously, is to run the top pair and the bottom pair, off of seperate amps. Otherwise, you need an amp that is spec'd to handle 2 ohm loads, to be safe.

You mentioned NAD as a possible amp... funny you should mention that, because my "insanity attack" system (3 pairs of JBL L100s stacked, see this thread: http://www.audiokarma.org/forums/showthread.php?threadid=13449 ) was in all reality, about a solid 2 ohm load... and it was running off of a NAD C320BEE baby integrated amp (50w/ch) which NEVER FLINCHED. We had output to near "pants legs flapping" levels, not a problem. Most of their amps are rated at 2 ohm stability, so if you decided to upgrade, they'd be a good thing to consider, IME!

As for optimal speaker orientation: I'd be inclined to put them, with the tweeters "inward"... ie, the bottom one tweeters-up , and the top one tweeters-down, so that the tweeters were as close together as possible. This will increase the "sweet spot" that they'll sound good in, WRT to standing up and sitting down, different vertical listening points and all that.

Also, with THIS much woofer, I'd be inclined, believe it or not, to put the whole she-bang on about a 12 to 15 inch tall stand, to get the bottom speaker off the floor. Believe me when I say, a 4311/L100/4312 sounds LOTS better in the bottom, when it's NOT flat on the floor... MUCH cleaner bass!

Regards,
Gordon.
 
Oh, and if you decide to add a sub... there's NOTHING like a good JBL B460 cabinet, or a clone thereof, using the JBL 2245H or 2242HPL 18" woofer, matched with the JBL BX63/BX63A electronic crossover or equivalent. Only subs I'd seriously consider, to match the "character" of this system! With a B460 or two added to THIS system, you could move the house foundation! :D

Regards,
Gordon.
 
Gordon,
thanks for your reply and I can only dream of duplicating your Insanity Attack system! Awesome

Anyway, yes these speakers are about fifteen inches off of the floor and are separated from each other with 1/4 inch rubber(I used excess turntable rubber). The 4312c's are on bottom, they have the tweeters on top/4311b's above tweeters below, they are stacked properly in that regard. I was afraid to attempt to wire them accordingly to polarity and I am ashamed to say I already cooked my luxman L-80V due to this setup. Oh well, live and learn!

I guess I need guidance on how to properly power and wire these speakers without damaging any more equip. etc. I also am considering using my pioneer sx 950 as pure power through an sae p102 pre amp, I do have other options for power. The optonica will not allow usage as a pure power amp.

look forward to your reply,

Matt
 
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