help connecting a sub to a 2 ch amp

[DukeofRedfern]

Comrades, some help please. I've toiled all day but found no answer to my problem.

 

I have a Yammy sub with a single rca input. That's it. I have a simple 2 channel amp with NO sub out, no preout, nothing but speaker and standard device inputs.

 

I want to add this sub to the amp, to compliment the two stereo speakers it drives. ATM i have it connected via the line out on the amp, using a Y rca into the single line in on the sub. This seams to make the sub work, but I can't control the sub volume via the amps volume control. This isn't satisfactory.

 

Does anyone have a solution?

 

I've read some confusing suggestions that I can use the same Y rca cord and connect from the line in on the sub to the speaker posts on the amp. But its unclear. Can this be done? I'm exasperated.

 

Anyone?

[DukeofRedfern]

Oh, its a powered sub.

[Weka]

You'll need to get a tech to wire up a sub-out socket on your amp that sums the left and right channels via isolating resistors from a suitable internal source (preamp output to amp module inputs). Without knowing the specifics of your amp, that may or may not work. The other option would be to cut your losses and buy a more suitable sub.

 

Edited July 14, 2017 by Weka

[Pieface]

Getting the channels summed together for the mono input will be the tricky bit

 

You can get the speaker level back to line level with something like this:

 

Speaker to linelevel

 

Probably better to look at changing the sub to one with speaker level inputs or the amp to something with preout or preferably subout.

[DukeofRedfern]

Thanks for the reply. The amp is a simple, bare bones number designed for audio. Speaker inputs and inputs for a cd and phono, and a line out. That's it. Basic.

 

I can't see you suggestion as viable. It would be easier to get a different amp. I'm trying to find a solution with the pieces I have. Thanks tho.

[DukeofRedfern]

Thanks pie. Would using that converter mean I could connect to the speaker lugs on the Amp? Allowing the volume control I'm seeking?

[Weka]

31 minutes ago, DukeofRedfern said:

Thanks pie. Would using that converter mean I could connect to the speaker lugs on the Amp? Allowing the volume control I'm seeking?

Yes, but it will give you a stereo signal, not the single summed mono you require.

 

[WhakPak]

I've never seen a subwoofer with a single input option. Are you sure that subwoofer doesn't have other connection options, like high level inputs?

[Bunno77]

If rca is the only input there is one product that I know of that will work. In most car audio shops (I know lifestyle store in Parramatta has them) there is a product that you wire into your speaker terminals and it will output an rca for your sub. Pretty cheap from memory maybe $50 max.

 

I don't know what they are called but car audio guys will know what you're on about.

[Happy]

It costs about $15 shipped from eBay. Search Hi to low converter.


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[DukeofRedfern]

Thanks for responses all. I bought a line level converter from jaycar for $15 and it seems to work, certainly better than before, but I acknowledge Weka's comment that it supplies a stereo signal to the sub, rather than the summed signal it requires. Not sure how to resolve that. But the Converter has improved the sound, and I have volume control. What it has done is restore full signal to the Onkyo's, restoring their lovely sound.

 

To WhakPak, the sub was once part of a yammy HTIB, and indeed has only a single line in (rca). The model is a NS-SW280, part of an NS-P280 set up. Google will show you images and specs. I've seen others online with the same single input, usually connected to an amp with a dedicated sub out, and usually from a HTIB set.

 

I'm only using this small sub in a bedroom setup connected to a TV and a kodi box, with the simple amp, a couple of nice Onkyo D-105f three-way towers and now this little sub to round it out. Proper audio is downstairs, provided by a Yammy AS-500 driving four vintage Aaron CS-4's, an Oppo 95 for discs, a Minix Neo U1 box, a Sangean DAB/Internet tuner and a very fine Sonab 85 S turntable.

 

If anyone has any ideas about the summing issue, I'm all ears.

 

Thanks again for the responses. really helped me.

[Roumelio.]

The most crude solution is just to go from your tape monitor out which will give you a straight line out through to your bass driver. The inherent problem with that solution is that it wont give you any gain control, and you will have to adjust your bass driver manually which is a real pain in the arse if you like to touch the volume dial a lot.

 

My work around for this problem is home automation, I run a simple streaming device (in my case an Apple TV 3) to my amp using a DAC and for digital sources, that means I can leave the amp as set and forget and adjust the volume by remote.

 

With this solution, you can, in a pinch use a 2 into 1 RCA adapter for bringing your signal down to mono also. The real problem really is that it will send the full frequency to your sub woofer and if your sub doesn't have a crossover it makes the whole concept unworkable until you get a high to low converter on that line, or some sort of crossover on that line. You can buy a simple electronic crossover on ebay these days for not much money.

 

I don't particularly like the concept of speaker to line level adapters as you lose some quality in sound in bringing your speaker terminals down to a line level and then boosting them back up again from the line level. It works in a pinch but its hardly an audiophile solution.

 

I think of these as nasty little devices that you use in these cars that send all their wiring through one loom where you don't want to lose the dash and stalk as a result. I don't consider them feasible long term solutions for hooking up a high quality set of speakers to an amplifier in a house.

 

The most straightforward solution is usually simply by running your speaker terminals into the speaker level input on the back of your sub woofer and out the other side again, this will bring everything into the same loop and will impart some level of change in your ohm output, but not enough to be problematic. The real problem is that you lose SQ in the process.
 

Edited July 19, 2017 by Roumelio.