Connecting subwoofer ? - AVS Forum
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Old 08-19-2013, 04:57 AM - Thread Starter
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Hey guys,

Bit of a newbie with regards to hooking audio equipment up. Have recently replaced the sub in the lounge with an HRS and decided to move the old one to the bedroom. A Jamo E7 Sub


It has 2 RCA plugs on the back of it. No speaker level inputs.

I have a little tripath amp in my bedroom powering some Cambridge Audio S30s.

The tripath amp is connected to a DAC which is connected to a PC via SPDIF.


If my understanding is correct...

I can buy two 1 RCA - 2 RCA splitters and connect one to each output on the DAC. From there they would plug in to the amp and sub ?


My understanding is this would feed the sub the full frequency so I would have to set the crossover accordingly and the volume would be independent too.


Alternatively - If anyone knows of any reasonably priced small 2ch amps that have a sub preout..


Cheers
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Old 08-19-2013, 05:01 AM - Thread Starter
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Also -

just looking at a picture of the back of the sub

http://www.avx.hu/forum/uploads/post-33-1265810762.jpg


the right input says in and the left input says.. out?

I thought they would both be inputs...so confused
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Old 08-19-2013, 05:56 AM
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Quote:
Originally Posted by leithm View Post

Hey guys,

I can buy two 1 RCA - 2 RCA splitters and connect one to each output on the DAC. From there they would plug in to the amp and sub ?


My understanding is this would feed the sub the full frequency so I would have to set the crossover accordingly and the volume would be independent too.


Alternatively - If anyone knows of any reasonably priced small 2ch amps that have a sub preout..


Cheers

Your connection is correct, but you would need a Y-jack to merge the second LEFT and RIGHT RCA from the DAC to a single input RCA outputs to be fed into the SINGLE input of your subwoofer.
EDIT : Apparently you cannot join Left and Right signals as your technically shorting the outputs, you need something like this to merge the signals
http://www.edcorusa.com/c/44/s2mseries


The PC would serve as the Master Volume.

Yes you would need to adjust the gain,crossover and phase of the subwoofer to match the speakers
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Old 08-19-2013, 06:01 AM
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Theres not much inexpensive amplifiers with sub-out, an integrated amplifier with PRE-out / Power amp inputs might be your best bet once you decide to replace your tripath
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Old 08-19-2013, 08:45 PM - Thread Starter
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Thank you very much for clarifying that for me.

I had hoped there would be a way to plug it all together without buying a new amp!
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Old 08-19-2013, 08:47 PM - Thread Starter
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I feared there wouldn't be.

The only ones I have seen is the Cambridge Audio One and TEAC AH-01

Both too expensive
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Old 08-20-2013, 07:35 AM
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A headphone out from an integrated amplifier could also work, if you can stomach the wire from the front section.
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Old 08-20-2013, 10:03 AM
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Quote:
Originally Posted by qguy View Post

Your connection is correct, but you would need a Y-jack to merge the second LEFT and RIGHT RCA from the DAC to a single input RCA outputs to be fed into the SINGLE input of your subwoofer.

The PC would serve as the Master Volume.

Yes you would need to adjust the gain,crossover and phase of the subwoofer to match the speakers
You'd also have to figure out a way to high-pass the signal to the mains amp.

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Old 08-20-2013, 11:51 AM
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Quote:
Originally Posted by qguy View Post

Your connection is correct, but you would need a Y-jack to merge the second LEFT and RIGHT RCA from the DAC to a single input RCA outputs to be fed into the SINGLE input of your subwoofer.

You can't just simply merge the signals like that. Splitting a signal with a y-adapter is fine. Merging is a no-no.

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A headphone out from an integrated amplifier could also work, if you can stomach the wire from the front section.

Not if plugging into the headphone jack silences the speakers.

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You'd also have to figure out a way to high-pass the signal to the mains amp.

Why? That's not necessary.

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Old 08-20-2013, 03:42 PM
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For music it should be ok. unless the 2 "front" speakers is really small.
For 2 channel HT, yes a high pass would be required to protect the small speakers.
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You'd also have to figure out a way to high-pass the signal to the mains amp.
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Old 08-21-2013, 06:10 PM - Thread Starter
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So Do I need 2 Y-Adapters or 3? The third being for merging the two cables to plug in to the INPUT on the sub
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Old 08-21-2013, 06:18 PM
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Quote:
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So Do I need 2 Y-Adapters or 3? The third being for merging the two cables to plug in to the INPUT on the sub

Apparently you cannot join Left and Right signals as your technically shorting the outputs, you need something like this to merge the signals. I have edited my response above

http://www.edcorusa.com/c/44/s2mseries
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Old 08-21-2013, 07:18 PM - Thread Starter
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Thanks.

I don't get why I can't just use the left and right RCA connections on the sub seeing as I would have two rca cables with left and right signals ..
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Old 08-21-2013, 08:16 PM
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Quote:
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Thanks.

I don't get why I can't just use the left and right RCA connections on the sub seeing as I would have two rca cables with left and right signals ..

Yes, you have two RCA out for left and Right, BUT your subwoofer has only a single INPUT
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Old 08-22-2013, 02:21 AM - Thread Starter
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sily sub not having speaker level inputs

Well ..

I will just buy another amp
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Old 08-22-2013, 12:17 PM
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Quote:
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sily sub not having speaker level inputs

Well ..

I will just buy another amp

No speaker-level inputs has become pretty common, nowadays.

Another option might be buying another identical subwoofer and using one on each channel. Although, honestly, with that particular subwoofer, I can't really enthusiastically recommend doing that. But if you could find one for the right price.........................

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Old 08-22-2013, 01:57 PM
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A 2x4 MiniDSP is right up your alley.
Feed the DAC's outputs to the Mini's inputs for XO and summing for the sub. The summed low-passed output is then taken from the Mini and fed to the single RCA input on your sub.
The high-passed stereo outputs from the Mini will feed the main's amp. No splitters are required.
You must use the Advanced 2.1 plugin for the Mini. Since you're using a PC as your source component, you can use it to run the plugin during setup.

Without knowing the signal levels, I can't tell you if you need a balanced 2x4 or whether the unbalanced will suffice.
Do you know, or can you acquire, the specs for the output levels of the DAC and the input sensitivity of the main's amp? If you don't, or can't, the balanced version is the safe way to go.
I'll assume the sub has a high-sensitivity plate.

Two would seem to be two too many to me too.
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Old 08-22-2013, 06:00 PM
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Some dont even come with crossover controls ...

I like the suggestion of looking for an identical subwoofer to solve the single RCA limitation of the subwoofer, that wicked smile.gif. Been trying to do the same for the bedroom as it has a small 8 inch JBL subwoofer in the corner and when the bass hits, I can tell the bass is coming from one corner, sadly I could not find the same JBL subwoofer at the right price

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No speaker-level inputs has become pretty common, nowadays.

Another option might be buying another identical subwoofer and using one on each channel. Although, honestly, with that particular subwoofer, I can't really enthusiastically recommend doing that. But if you could find one for the right price.........................
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Old 08-24-2013, 10:08 PM - Thread Starter
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Old 08-25-2013, 12:13 PM
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here is the dac

http://www.tpdz.net/en/products/d20.htm

and the amp

http://www.tpdz.net/en/products/tp22.htm

I'm not sure if you were addressing that to me. But...

Plenty of output from the DAC and 200mv input sensitivity on the power amp (per Parts Express) means an unbalanced 2x4 Mini is a good fit (cheaper too).

The Mini can output a sizable transient when switching it off/on, so don't have the power amp running if you're going to work on the Mini's power supply or its connection.
Leave the Mini always on. I do recommend a 12v power supply, as this will allow you to connect and disconnect the USB without switching off the power amp.

Two would seem to be two too many to me too.
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Old 08-27-2013, 01:54 AM - Thread Starter
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Thanks a bunch.

Should I order Max Input Jumper RevA or RevB ?
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Old 08-27-2013, 06:33 PM
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It doesn't matter, you can switch the jumpers yourself.
I'd order the Rev A (.9V).
If you're overloading the inputs too easily, you can switch the jumpers to Rev B (2V).




For reference, the RCA jacks are the inputs.

The jumpers are in the red rectangle.
The jumper on the left has had its jumper removed for clarity.
The jumper on the right is set for .9v.
For 2v (Rev B) input sensitivity, move both jumpers to the right so each has its left pin exposed.
If you forget, the board is marked.

Two would seem to be two too many to me too.
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Old 09-02-2013, 06:23 PM - Thread Starter
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Heyyy,

So I got it all hooked up.

It sounded good for a bit then after a while the subwoofer started thumping away more than it shoulder and the audio was became very distorted through the speakers.

Any ideas?

I followed the sub integration guide on the minidsp website
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Old 09-03-2013, 12:35 AM - Thread Starter
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flicked over jumpers

crisis appears to be averted !
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