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Two pairs of spkrs in tandem

I need the help of the technically minded and capable folks on this great audiophile panel.
I am running B&W original 80 series 802's as my primary spkrs. rated at at 8 ohms..... tweaked..re-wired and all inards hard wired, soldered with cardas, great solid copper binding posts & Sand filled and tensionized side dampers to control box resonance in this (pre- matrix) design.

I have attempted to intigrate my other pair of favorite spkrs, 1996 Sound Dynamics 300ti's rated at 4 ohms, with their propietary titanium dome tweeters and run them in tandem with my 802's

In principal they have added a great deal in capturing subtle detail as well as in specificity and depth in the sound stage, most certainly in (over-all) dynamics and clarity

Basically "I love the sound" the 300 ti's seem to add that extra level of transparancy, reveal and crispness that the the B&W's didn't quite capture on their own...

THE SNAG however is a low level HUMmmmm!!!! coming from the Sound dynamic spkrs......

Mine is a complex set-up.... featuring A stereo pair of Janis SUB WOOFERS crossed over at 100 HZ and powered with their own dedicated W3 100 watt JANIS AMPS..

Also a pair of TOWNSHEND "super tweeters" connected to the B&W's

I built a (glued & screwed) MDF coupling that positions and holds the the 300 ti's upside down (forming a 6 foot high 9 driver (per side)"array" tweeter to tweeter assembley.. COOOL!!!

THE WHOLE THING IS A TERRIFIC REVALATION FOR ME!!!!! EXCEPT FOR THE ANNOYING HUMmmmmm!..

I've checked and re-checked the integrity of all connections to no avail...

If I re-move the 300ti's.. the hum is gone???...

IS it the B&W 8ohm Vs the ti's 4ohm mix??. Is that creating some kind of dichotomy causing the hum in my otherwise silent set_up ?...

I would love some help on this.... THANKS..
tweakyman
tweakyman OP
21 posts
 
Manoterror, I forgot to adress your concern regarding over-taxing your amp.. Please take a look at Hifihvn's response to this thread. He talks about this type of parallel connection in a tandem speaker set-up resulting in an impedance drop. The amp I am using is rated at 300 watts per chnl into 8 Ohms and 500watts per chnl into 4 Ohms.
Other than the amp running a little warmer after a long listening session, everything seems OK..I'm not familiar with your amp...so I can't comment on how it would react to the additional load.
hifitime
715 posts
 
In both situations(Manoterror and Tweakyman),it may be better to bi-amp with a second amp to be safe.Tweakyman, your still driving your amp hard,those figures posted above don't include any low impedance dips that either of your speakers may have.If either speaker drops lower(it is common for them to do this)than the 4 or 8 ohms nominal(average),it may dip down to 2 ohm,or lower(with the two in parallel), and may put your amp at risk.Short term may seem ok,but the extra heat sure could be a problem.With a second amp,you could match them up to the upper and lower speakers,and possibly come out with better sonics too.
manoterror
216 posts
 
Yeah, I am using the C connection in a bi-amp for my Mirage speakers, and that works great. I am concerned that the amp won't be able to handle the drop to a 4 ohm load with the 2 speakers. Not really made for that I don't think. I'm pretty sure that wiring it like Twekyman would definitely present to low of a load.

I was hoping that by using A&B, it would assume an 8 ohm load for both, just with less overall power to each. Assumption...I know. :-) Interestingly, the Orb systems use 2 of their 8 ohm balls in the method Tweakyman setup...and they say most receivers can handle it.

Why must I always want more! :-D
tweakyman OP
21 posts
 
Thanks Hifitime. Point taken and very much appreciated.
manoterror
216 posts
 
Okay, so I learned I need to read the manual once in my lifetime. :-) The Marantz receivers have the option of a using the rear-surround discrete channels to do a true bi-amp setup. I thought it was merely bi-wired.

So, I can use that separate set of amps to run the second set of speakers, as they both get the full signal. So there is one advantage of a receiver....but just one. :-)

So I'm gonna do that with the Gallo Adivas. Yeay...office system.
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