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..... 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!!!


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..
Passive loudspeakers cannot generate hum, only reproduce it. Now, are the 300ti's in parallel with the B&W's? Your actually wiring circuit is unclear to me from what you have posted.

Keep in mind your dropping the impedance down to about 3.429 ohms with the 6 and 8 ohms parallel.I don't know if that could be causing a hum problem,but may be low for your amp.
Sorry,with the 4 and 8 ohms in parallel,its about 2.667 ohms.Worse yet.
I didn't know Phil Spector was out of jail. The "wall of sound" approach has been tried many times, it will work to some degree with 2 pairs of identical speakers but using dissimilar speakers will result in a sound you may find pleasing but cannot be accurate.
I've been contemplating doing the same thing with 2 pair of matching Anthony Gallo A'Divas. Kind of a poor man's Reference Strada since I can't hear above 18khz anyways. :-) Although I am thinking of just running them on both A and B speaker outputs.

How did it work out for you? What was the sonic improvements you heard?
"Although I am thinking of just running them on both A and B speaker outputs. " Why? It is the same amp anyway.

Kr4. Thanks Kal.
I ran a pair of short speaker cables, bannana plugs on each end from the B&W's terminals up to the ti300's. I also tried to run the added speaker cable out of the Moscode 600 amps terminals where the B&W's are connected, but that did not eliminate the hum....
Thanks HiFihvn.
I'm running the speakers out of my NYAL Moscode 600.

As the Subs have their own 100 Watt dedicated amps and are crossed over at 100hz there doesn't seem to be overt pressure on the Moscode, although it does seem to run a bit warmer than usual with this 2 spkr set up.
Thanks Stanwal.
I'm sure your absolutely right but the sound is clearly superior to me than either single pair on their own.
I have tried all my front ends using reference material that I am very familiar with. As a musician I am very conscious of timbrel accuracy and the quality of the sound of acoustic instruments.
This set up shouldn't work and yet it's a huge improvement
I'm hearing nuance and subtle dimensional stuff I've never heard on these recordings before. I make no argument as to your point this "cannot be accurate" but it does sound good. Now if I could only get rid of the hum..
Hi Manoterror.
I really enjoy the improvement. The stage is Huge and better defined. There is more detail right across the board. The rendering of drums in acoustic jazz is particularly exciting. With orchestral stuff it just feels more powerful and real. I'm hearing deeper into the sound stage than before..
According to Stanwal's comments, you may well get even better
results seeing as you have two sets of identical speakers. I wish you good luck with this and hope you don't get an annoying hum
I sold my Moscode 600 when I saw that I was unable to contend with its high level of hum,which got much worse when reconnecting after it was not used for a year.
Thanks Reylon.

I think you've nailed it....There is a low level hum (60hz)or (fan motor)? coming from the Moscode. I suppose I've gotten used to it having owned it since it was new. Kal Kr4 in the first response to my thread intimated that a passive spkr would not be the origination of such a hum, so he was right and I should have checked further upstream right away.

the hum never came through the B&W spkrs but I guess the sensitivity or filtering in the 300ti's which are more revealing in general is allowing and further amplifying this low level hum. Now I have to decide whether this tweak is worth it. I have fought hard to have a silent buzz and hum free set-up, so this annoys me...Thanks for your input...What amp did you acquire after selling your Moscode?
So I have a question on how you wired them. KR4 was asking why I would run them off the A + B terminals since they are off the same amp. I was thinking of this for 2 reasons. 1) Its simple, and I have 2 runs of cable. 2) I thought if I wired the speakers together, that it would drop the Ohms from 8 to 4.

So how did you accomplish this task? Is one way better than the other? As I see it, there are 3 methods:
1. Wire the speakers together (red to red, black to black) and connect a single cable to one of the speakers from the amp.
2. Use a bi-wire cable that isn't designed to have seperate treble and bass connections to both speakers, to one connection on the amp.
3. Use the A + B terminals with seperate runs of speaker cable to each speaker.

I would assume all of these might give the same result, but my main concern is the Ohm rating on the amp, as I'm running a Marantz SR7001 reciever and don't want to overtax it. :-)

I'm guessing it may still overload your receiver.They don't make it clear enough.If you use speaker"C" for bi-wire,they may assume a typical 8 ohm speaker split(by removing jumpers)that would give 16 ohms for highs,and 16 ohms for lows,total still 8 ohms,the same as it would have if the jumpers were left in. Page 20 is where they talk about speaker"C" switch.Page 23 says the SR 7001 doesn't have the multi-room feature. On some that may give an extra amp.I can't find anywhere that it says 4 ohms total is ok.Manual link.>[]
Hi Manoterror. All I did in regards to the hook-up was run a short 4ft speaker wire from the original bottom speakers terminals into the add-on top pairs terminals. Only the primary lower pair of speakers are connected to the power amps terminals.I connected high quality banana plugs to each end of the short (tail)speaker wires. the primary lower pair of speakers are connected with spades but there are banana female openings in the tightening nuts. This allowed for a simple method of dual connection. It seems to work fine. I had originally run both pair separately from the amp but changed it to the method I described above. There was no real difference in the sound...
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 I can't comment on how it would react to the additional load.
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.
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
Thanks Hifitime. Point taken and very much appreciated.
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. system.
Just an update on this "tandem speakers" set-up.
With particular thanks to Hifitime, I have carried out a change based on his thoughtful recommendation that Bi-amping would be the better and safer (less potentially damaging) way to achieve good results utilising two pairs of speakers simultaneously.
I am lucky to have an extra set of main outs on my pre-amp so it was pretty easy to integrate the amp module on my old Pioneer SX980 100 watts per chnl into 4 ohms. I find as Hifitime intimated this method would produce better sound and indeed it does. The stage is more natural and wide extending well beyond the speakers, everything seems to breath better and feel very relaxed. I should mention that I did not run my second pair of speakers through the hi-pass on my Janis cross-over amps, I took the full signal out of the Preamp directly to the Pioneer and of course connected the speakers with a new run of good speaker cable. In doing it this way I found that the bass response together with the pair of Janis subs in the room was too exaggerated. I decided to try and tune the rear ports on the Sound Dynamics ti300's bass reflex design speakers by first partially and then fully plugging the ports and that did the trick, it worked well.
I am more than pleased with how this whole thing turned out and I thank all those that weighed in on this subject.
Oh yeah, I almost forgot the annoying "HUMmmmm" is gone, the whole system is once again quiet...