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Connecting Subwoofer for Vinyl Stereo System

C

Chris_M

Active Member
Right now I have a little 5W single ended tube amp, Mission 751 speakers along with the phono pre and turntable. My setup sounds good but the speakers are a little low efficiency for the amp (amp is underpowered for my setup).

A friend has a subwoofer he is offering to lend me to try with my system.
PSB Subwoofer
http://www.psbspeakers.com/products/subwoofers/SubSeries-125-Subwoofer
Setup Guide/Manual
http://www.psbspeakers.com/content/120727145859-PSB_SubSeries_English_Owners_Guide.pdf

I think this is something I would like try and add to my system. I think the sub would suit the varying styles of music I listen to. It might bring back that bit of power and kick I am missing.

Question:
- How do I hook this sub up? Can I take the signal coming from the phono preamp or should I take it off one of the speakers?
- If I take the signal off one of the speakers then the sub is in parallel with the speaker and the load impedance the amp see's is different. Not sure if this is an issue.
- looks like the sub has a few different input/output jacks to accommodate things


Thanks :tresbon:
Chris
 
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I think the best option is to just connect it to the speaker outputs, but you need to connect both channels unless it's a mono setup.

The sub has an amp inside so yor tube amp doesn't see the subwoofer as another speaker load. It sees it as a parallel high impedance load. So, for discussion, say your speakers are 8 ohms. With the sub in parallel the net load is likely something on the order of 7.99 ohms, no material difference from 8 ohms.

If you are running a preamp or the phono pre has a volume control, then connecting the sub between the preamp and amp or between the phono pre and amp is a viable option. This would also have potential benefit of providing a high pass filter to reduce the bass load on your amp, provided you also take the sub's line level outputs back to the amp inputs.
 
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Thanks for the advice

I think I will try just hooking the sub up to the speaker to start.

1. Why do both speakers connect to the sub? There is a single speaker, how can a single speaker be stereo?
2. Since my amp is 5W will I be setting the sub's volume very low?
3. What is the general consensus/thoughts on subs with vinyl setups? I don't see many members here using them.
 
It's not stereo, but a summing circuit in the sub ensures any bass from either channel gets to the driver. If you connect only one side then you get none of the potential bass content from the other channel.

Don't know. Set it to 1/2 way and go from there.

Don't know, not really into records, but I see no reason not to other than a purist approach or possibly concern of low frequency feedback.
 
Chris_M said:
3. What is the general consensus/thoughts on subs with vinyl setups? I don't see many members here using them.
Click to expand...

whoaru99 got the first two questions spot on. As far as using a Sub with a Turntable, I have that kind of setup here on my near-field system.

Since the Turntable is fairly well isolated and the Sub is set to suitably low level - only about 1/4 up on it's volume control - I don't have any issues with feedback. Can't really ever see running this system loud enough to even approach feedback levels.

Mark Gosdin
 
Get cornerhorns! Klipschorns, Cornwalls, Heresy, Belle, or LaScala. Chorus or Forte also good. Crites crossovers and titanium tweeter elements. No sub needed.
 
Maybe less so, but 5 watts single ended is a high efficiency loudspeaker kind of application. Does our OP's subwoofer have a speaker level option? Might work well, but do consider keeping the bass level on the conservative side unless you have a subsonic filter on the preamp.
 
Got the sub hooked up :banana:

Got the volume set a little under halfway and crossover set at 130 Hz. I am wondering if this is correct though as my Mission 751 speakers have an advertised frequency response of 50 Hz - 20k Hz. So shouldn't my crossover frequency be set at around 50 Hz?

Also there is switch
Low-Pass Crossover: There is an external/internal crossover switch on the back of the powered sub. If you select the "internal" position, the low-pass crossover adjusts the high-frequency roll-off of signals sent to the subwoofer. The control is continuously variable from 50 Hz to 150 Hz, and allows you to precisely match the subwoofer's bass production with your system's main left & right stereo speakers. If you select the "external" position, the powered sub's low-pass crossover is bypassed.
I set it to Internal so I could use the Crossover control. I can't see why I wouldn't set it to internal. Thoughts?

Thanks!
 
You might have to tune the crossover point by ear. Your ear will tell you when it's right for your system, your hearing, and your room.
 
In your setup using the Sub's internal filter is the right way to go, if you were installing the Sub in a Home Theater setup where the receiver had it's own filter then you would switch the internal one off.

You might want to try moving the crossover point closer to 50hz to match your speakers. I experimented with mine when I first set it up, but ended up leaving it at it's original factory setting - about 120hz if I recall - since the speakers & sub are all Pioneer and it appears were meant to work together out of the box.

Enjoy the sound.

Mark Gosdin
 
In theory the frequency output from a sub is low enough that you shouldn't be able to tell where the sound is coming from. However, the higher you turn the crossover frequency the more localized the sound will be. In other words you'll be able to tell that the sound is coming from the sub instead of from the speakers.

I believe that I've got my crossover set at around 60-70hz but I just adjusted the crossover until I got good bass response and I couldn't tell exactly where the bass was coming from any more instead of shooting for an exact frequency. Also experiment with placement of the sub (and speakers) and see what effect that has on the sound. Putting it near the corner of the room will strengthen the effect of the sub.
 
A good place to start with the low pass filter on the sub woofer is the -3dB point of the main speakers. Once you have the crossover point set turn the level on the sub up until you can hear it, then back off until you can't actually hear it. At the right level you should be easily able to tell when you turn it off but not actually hear it while it's on.
 
JoeESP9 said:
A good place to start with the low pass filter on the sub woofer is the -3dB point of the main speakers. Once you have the crossover point set turn the level on the sub up until you can hear it, then back off until you can't actually hear it. At the right level you should be easily able to tell when you turn it off but not actually hear it while it's on.
Click to expand...

So in my case set for 50 Hz then boost the Volume/Gain until I can hear the sub then back it off?
 
Chris_M said:
So in my case set for 50 Hz then boost the Volume/Gain until I can hear the sub then back it off?
Click to expand...

Bumping to confirm

Got the sub set up and wired into a corner (I know not ideal or most balanced option).

Got it dialed in to 110 Hz currently
 
If 50Hz is the -3dB point of your mains yes. Otherwise set the crossover on the sub woofer to the -3dB point of your mains. Turn the volume up until you can hear the sub woofer. Slowly back off on the volume until you can't hear it.

These two tips should get you in the ballpark. The exact settings will depend on your ears, your room and your speakers. Be prepared to do some tweaking until you get it just right. Once you do, no further adjustments should be necessary.

Ideally, you should not be able to tell that you have a subwoofer until you turn it off.
 
Chris_M said:
Got it dialed in to 110 Hz currently
Click to expand...

110hz seems high. You might try around 50 - 70. If you have it too high you get both the main speakers and the sub playing the 50 to say 110hz signals which results in too much volume in that range.
 
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