Axiom Home Page Forums General Discussion Home Theater Help With Dual Subs

Hi,

Apologies for not babbling about my visit to Axiom last week. Had a great time and will post about it when time permits. Since getting back home the contractors have returned so my time is not my own.

.........for anyone who would like some cheese with that whine I have a very nice old sharp cheddar.

Now to the problem at hand, last night I spent many a happy hour trying to get two subwoofers to work.

I suspect the answer is a very simple one but come midnight I gave up on the problem. I thought I'd turn here for a little help as I don't seem to be able to find a quiet minute to think this through.

As I used to create engineering drawings before I retired I thought I'd show you all the options I tried, I hope it's not too technical for everyone.





Option A - cable to sub #1, it worked
Option B - cable to sub #2, it worked
Option C - using "Y" & cable to sub #1, it worked
Option D - using "Y" & cable to sub #2, it worked
Option E, using "Y" and cables to both subs, Nothing Worked.

I know the curious amongst you will wonder how i managed to find the time to do the drawing when apparently i don't have the time to solve the problem.... a topic best left for a later date.

Receiver Denon AVR890
Sub #1 Axiom EP3350
Sub #2 Paradign DSP3400
Two different Y-cables were tried both male to 2 female.

Your thoughts?

hmm, assuming your splitting it at the sub pre-out jack on the receiver it should work fine. For my 2 350's it works that way, or if I just run one coax to Sub1 pre in, then a second shorter cable from Sub1 (preout) to Sub2 (prein). What if you do option A above, but then run a cable from the 350 to the other sub (name not mentioned here).

Are both subs set to power on when a signal is detected? If so, try the On setting instead of Auto. Any better? The subs might not be getting enough juice when the signal is split.

makes sense I'll try it tonight when the herd has gone home.

I still don't know why the current setup won't work.

lunch is over, back later....

Puzzling. Too bad there wasn't a way to tap into the circuit with a multi-meter when they are plugged in.

[Edit] A thought, maybe you could use your extra Y connector for that. You don't need one on both cables. Put it on the sub you are running, measure, then plug the other sub in and measure again.

Long cables?

I'm thinking the same as Kruncher; that your receiver isn't putting out enough voltage to wake them both up.

where do you have the dB levels set for the sub channel, maybe you have it at like -12dB, which ties in with what Krunch and Tommy Boy say... Why not let Audyssey do the work?

The answer is as simple as the diagram. You ran out of Boom Boom at D.

Let me know when its back. I like my cheddar with Boom Boom.

Wayne, the high level of technical complexity of your drawings did in fact require considerable study to determine why you were complaining. What can be said at this point is what the problem isn't: connecting a voltage source in parallel to two loads doesn't create a "voltage divider" in the technical meaning of the term(a series connection does that); each load receives the original voltage. For example, if the sub out from the receiver at a particular instant is 1 volt, each sub amplifier connected in parallel receives 1 volt(not a half volt).

That's all very well, but the question of course is what the problem is, then. It appears that both branches of the "Y" and both coax cables are working separately, but didn't work together in "E". This makes no apparent sense. Although the amount of time that you spent indicates that you probably double-checked the connections carefully, I'll nevertheless suggest one remote possibility which afflicted one of our members a few years ago: in making cable changes he inadvertently plugged into the multi-channel sub input on the receiver rather than the sub out. Are you certain this didn't happen when you ran "E"? If this isn't it, I'll continue to ponder the matter, but my next best guess at this point would be Fred's suggestion that you ran out of Boom Boom after "D".

What are the exact Y-cables you are using? I have experienced something similar before setting up dual subwoofers and it was caused by using a very cheap splitter. A single sub would work on either end of the Y but combined only the one sub would work. The quality of the splitter was exactly what you see in the supplied cables when you buy a DVD player but a male to 2 female adapter equivalent.

Make sure the splitter is spec'd for 75 ohms. I purchased a splitter from Blue Jeans cable for $2.50 and it solved the problem. Perhaps you have a similar issue with the Y splitter you are using.

Can't the out of the 350 be used to connect the second sub? This way the y cable is out of the equation.

As suggested I did try the Axiom out to the other sub and it worked just fine. I still don't know why the Ys won't work. One Y is an Acoustic Research and the other is Future Shop crap.

When I retire I'll have the time to sort out things like this... wait I am

John I checked all the connections many times, I still think it's something very basic. "The fault, dear Brutus, is not in our stars, But in our cables."

On a positive note my brother-in-law came over tonight and continued on with his quest to make me an opera fan.

Now it's not going to happen but we listened to a documentary on Anna Netrebko with the M60s and VP160, he simply could not believe how good her voice sounded on the speakers, said it was the best he ever heard.

And yes I ran Audyssey 3 times today.

thanks for the help.

I don't use a y-cable, but actually a gold plated adapter.

It pretty much has to be those Y cables, any way you could test them on some other audio component like a cd player RCA out and see if the subs then work? I always thought about using a typical F connector on the end of the original wire off the sub out at the amp, hooked up to a a normal Coax cable splitter then out to each sub.

Good point Jason, I'll test the cables on an old cd player. On another related point, any reason I can't make a subwoofer cable out of Axiom speaker wire, would the shielding be adequate? I just love the flexibility of that wire.
The above thought may be in error, it's early, I haven't had my coffee yet and winter finally arrived to southern Ontario. It's time to dust the cobwebs off the snow shovel.

do you have a link to the products you purchased?

If all you want to do is connect the LFE Out from your receiver to the sub, then you could use RG8 Coax.
Using 12 gauge wire is unnecessary, being much too large for no good reason (the signals are Line level); and the shield would not be any better than that of the coax.
if you use RG8 Coax, just be sure it's 100% shielded.

Order the Calrad Hardshell Y adapter, 1M/2F RCA from Blue Jeans cable.

Post links of the actual splitters you are using.

Hi J.B. and all,

Speaker cable isn't shielded at all; it carries a high-level signal. Low-level (line-out)LFE sub-cable signals must use shielded coaxial cable to avoid pick-up of AC hum and external interference.

Ford Prefect: If the line-out signal from one sub to your second sub works well, why not use it? No point in obsessing over why your Y-adapter arrangement isn't working.

Regards,
Alan

Hi Fordprefect,
I have used RG6 which is not expensive and easy to find for long subwoofer low level in runs without any issues. If the connectors at each end are well made and of good quality then it will be great.

FordPrefect, I had a similar issue as yourself, and did the same trouble shooting that you did.. in my case i wound up turning the SUB gain on my processor up a considerable amount, maybe from 3->8 or somewhere in that range.... i then adjusted the gains at both subs one sub i had to turn the gain up, the other sub i had to turn the gain down...


When i was trouble shooting, i went so far as to pull the amp from my EP600, thinking i was having an amp problem again..... when you have both subs in parallel, have you placed your hand on the driver to see if there is any movement?

How are you verifying "Nothing Worked"


The way i eventually discovered i just needed to adjust the gain was to turn the volume up while placing my hand on the driver... When the drivers were moving just a little bit at a louder than normal volume, but not audible i knew they were A) They were receiving a signal
B) not receiving enough signal.

My EP600 is about 13-15ft from my processor, and my JLB is about 6 ft away.... i am using a Radio shack Y splitter....

Hope this helps.