Subwoofer funtions better when audio signal sent directly rather than through an amplifier

Nat Arumugam

Nat Arumugam

Audiophyte
Hi folks,

I have a studio monitor speaker, presonus ceres c3.5bt. And I recently bought a subwoofer,polk audio psw10.

When I gave a connection from Presonus subwoofer out (1/4 inch stereo) to Subwoofer in (RCA), I see less throw on the subwoofer paperdiaphragm, though there is little bit output with full volume on subwoofer. Instead I gave input from Iphone to subwoofer (3.5mm to RCA), it really rocks.

Why it so? What is going wrong when I connect from presonus?

Thanks for your reply.

Nat
 
TLS Guy

TLS Guy

Seriously, I have no life.
Sonus only let you look at the user manual for those active speakers if you are a registered owner so I have to guess.

I have no idea of the frequency of that sub out. By the look of the back panel the output does not seem to be adjustable.

If you do not have enough bass with the control on sub turned up full, then you have not bought the right subwoofer. You have bought a pretty lousy sub by the way.

You likely need a more potent and above all one with more gain.

That might not solve it. What you have bought at first glance looks like something that should be avoided all together, and I mean the whole rig.

Your other option is to obtain or build a simple premap to interface between your speaker sub out and the sub to increase the gain.
 
TLS Guy

TLS Guy

Seriously, I have no life.
The problem is that you can not guarantee that sub will solve his problem.

I have a strong hunch that his problem is one of gain structure more than anything else.

I have no idea what the sub out signal level is from those speakers. There are no specs and you only get to see the user manual if you have bought those wretched speakers. Sounds as if they have a lot to hide from the unwary.
 
D

Don G.

Junior Audioholic
It probably sounds louder when connected to your iPhone because it is getting the full spectrum of sound, including frequencies it shouldn't see. From the speakers, it only gets what gets through whatever filter the speakers have, maybe below 100hz or so, which should be fine by the way.
 
KEW

KEW

Audioholic Overlord
I consider these very nice speakers for the $150 or less you should have paid.
With 3.5" woofers, the bass is missing, but the mids and highs are quite nice!
I have used them with a sub to fill an office with good sound without any issues.
The sub I used was a Velodyne VMS-8, but I am surprised that any sub wouldn't reach a level that balances with the speakers.

What are the source(s) you have hooked to the Ceres 3.5's and how are they connected.
Where is your iPhone volume set, where is the Ceres volume set, and where is the sub volume set when the sub sounds good?

The "Low Pass" knob on your sub should be at around 2 o'clock to crossover well with the Ceres 3.5. See if that changes the way things work in any significant way (though I wouldn't expect it to unless Don G.'s theory is right and you currently have it set to 180 - as high as possible).

BTW, there is no manual for this product. It only comes with a "Quick Start Guide" which can be viewed here:
http://static.bhphotovideo.com/lit_files/105077.pdf
However, it offers no information that is useful for evaluating the gain structure.
 
WaynePflughaupt

WaynePflughaupt

Audioholic Samurai

When I gave a connection from Presonus subwoofer out (1/4 inch stereo) to Subwoofer in (RCA)
The subwoofer output on the back panel is not “stereo.” It is balanced TRS. If you are using the wrong cable between the Presonus and the sub, that could account for the problem. Can you post a link or picture for the cable you’re using?

Regards,
Wayne A. Pflughaupt
 
L

Latent

Full Audioholic
yeah I think Wayne has spotted the problem. You probably have a stereo -> 2xRCA cable which would be feeding the balanced + and - sub signals to the two left and right line inputs on the SUB. This will produce some weird audio output from the sub if it outputs anything at all. You need the + and - signals sent to one mono RCA cable to make it work

There are special TRS (Tip Ring Sleeve) to mono unbalanced RCA cables which is what would be ideal but they are not common consumer cables and are mainly used in DJ and pro audio situations.





Basically if you have a cable with a TRS end and two RCA's on the other end it will not work but if it has one of these TRS going to a single RCA then it will hopefully wired correctly to make it work for you. You can also get a TS ( see the right hand picture above) to single RCA cable it will also work.

Also note that most of these cable options will join ground and - signal together which can cause ground loop hums depending on your devices and how they are grounded. If you don't hear any problems then your fine though.

a quick amazon search:

http://www.amazon.com/Hosa-Cable-CPR202-Dual-Inch/dp/B000068O17/ref=sr_1_2?ie=UTF8&qid=1455159029&sr=8-2&keywords=balanced+to+unbalanced+rca

hard to find the right cable here though as most convert to balanced XLR cables but then you would need two cables (TLS->XLR and XLR->RCA) which is a waste of money.
 
Last edited:
F

fmw

Audioholic Ninja
Try using the speaker level connections. That should do it.
 
KEW

KEW

Audioholic Overlord
Try using the speaker level connections. That should do it.
That would only work for left channel. These are powered speakers and the amp is internal to the right channel speaker with speaker level going to the left channel.
 
F

fmw

Audioholic Ninja
That would only work for left channel. These are powered speakers and the amp is internal to the right channel speaker with speaker level going to the left channel.
Yes. Thanks for the correction.
 
WaynePflughaupt

WaynePflughaupt

Audioholic Samurai

Basically if you have a cable with a TRS end and two RCA's on the other end it will not work but if it has one of these TRS going to a single RCA then it will hopefully wired correctly to make it work for you.
I’ve searched the world over (or at least the Web) and have never found a 1/4" TRS to RCA cable. But I guess it makes perfect sense - it would do nothing in a TRS jack that a TS to RCA cable wouldn’t...

Regards,
Wayne A. Pflughaupt
 
L

Latent

Full Audioholic
I’ve searched the world over (or at least the Web) and have never found a 1/4" TRS to RCA cable. But I guess it makes perfect sense - it would do nothing in a TRS jack that a TS to RCA cable wouldn’t...

Regards,
Wayne A. Pflughaupt
Yeah not a common cable so a TS to RCA cable is probably the easiest thing to find. The only difference a TRS to single RCA cable would do is that the ground is kept separate to the - signal wire until it gets to the RCA jack end where it is wired together. TS to RCA will ground it at the TRS socket end and I don't know if you would really notice much difference anyway.
 

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