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553 posts

Ultimate Geek


Topic # 113572 21-Jan-2013 09:48 Send private message

Hi There,

In the weekend I bought a secondhand Technics SB-TW50 Subwoofer. The thing is a beast and I love it, I just want to make sure I get it set up properly, As it has no volume or crossover controls on the speaker itself.

My receiver is an entry level Sony STR-DH520. Front speakers are Kef C5's Only running a 2.1 setup.

I've plugged in the mic supplied with the amp for auto Calibration. After running the auto cal the receiver sets the volumes of the fronts ( Which are set to Small ) at -0.5 Db. And the sub at +10Db which is the maximum setting (Range is -10db to +10db)

I want to ensure I dont damage the subwoofer, and have very little knowledge of hifi, so thought I'd better ask if running it at the maximum Sub volume level is safe? The Spec's of the sub are as follows

TECH SPECS:
* Power - 100W + 100W
* Drivers - 2x 8" drivers with 2x10" passive radiators over the top
* Freq Range - 15Hz - 400Hz
* Size - 300 x 515 x 464mm
* Weight - 21kg

I believe it was the first Sub to gain a THX certification, it even has a Lucasfilm THX badge on the grill!

Any advice would be appreciated :)


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  Reply # 748102 21-Jan-2013 10:12 Send private message

Hi,

Where abouts have you located the sub? Is it next to a wall, which way is it facing.
When you used the auto cal function, where did you mount the microphone? (I usually place the mic at ear height in the centre seat of the couch at about foot to tv distance however the auto cal is more useful for surround sound set up rather than 2.1 (as it sets the speaker levels in relation to distance).

Whats the max input level of the sub?

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  Reply # 748103 21-Jan-2013 10:14 Send private message

FWIW best position for the sub is in the corner of the room, nearest to where you sit. Next best is any corner of the room.



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Ultimate Geek


  Reply # 748107 21-Jan-2013 10:22 Send private message

Gooseybhai: Hi,

Where abouts have you located the sub? Is it next to a wall, which way is it facing.
When you used the auto cal function, where did you mount the microphone? (I usually place the mic at ear height in the centre seat of the couch at about foot to tv distance however the auto cal is more useful for surround sound set up rather than 2.1 (as it sets the speaker levels in relation to distance).

Whats the max input level of the sub?


Thanks for your reply.

I placed the mic where I would usually sit, on the couch on the back wall in the center.

Its positioned inside of the right speaker facing the open lounge grill facing me. Its a front firing woofer.

It dosent actually state on the sub what the max input level is. There is very little info on the internet about it probably due to its age. It is totally self powered two 100W RMS amps run each 8" woofer independently.

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  Reply # 748116 21-Jan-2013 10:31 Send private message

Interesting...
You say there's no adjustment on the sub at all?
What setting has your amp set the LFE crossover to?
In regards to placement, I personally wouldn't put a dual driver unit like yours on the corner (it's called corner loading) unless you really feel like you're underwhelmed by the power...
Corner loading can give you up to a 6db boost, but it can come at the cost of bottom end clarity.
Essentially I'd recommend the old school method of putting the sub in your seated position, putting on some bass heavy music... And crawling around the floor, listening for the spot where the bass sounds the best. Reverse engineering and old school - it should be the best starting point IMHO.



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Ultimate Geek


  Reply # 748207 21-Jan-2013 14:02 Send private message

Dunnersfella: Interesting...
You say there's no adjustment on the sub at all?
What setting has your amp set the LFE crossover to?
In regards to placement, I personally wouldn't put a dual driver unit like yours on the corner (it's called corner loading) unless you really feel like you're underwhelmed by the power...
Corner loading can give you up to a 6db boost, but it can come at the cost of bottom end clarity.
Essentially I'd recommend the old school method of putting the sub in your seated position, putting on some bass heavy music... And crawling around the floor, listening for the spot where the bass sounds the best. Reverse engineering and old school - it should be the best starting point IMHO.


Hi There, That's right the only controls on the Sub itself are auto on. on/off and polarity. as well as a voltage selector.

Looking at the receiver manual the only crossover options are Front, Center, surround, and Front high speakers crossover. No option for the Sub.

I'm quite happy with the positioning of the sub. and the power is huge compared to the other speakers.



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  Reply # 748229 21-Jan-2013 14:47 Send private message

Wills1:

Hi There, That's right the only controls on the Sub itself are auto on. on/off and polarity. as well as a voltage selector.


Interesting! I found some pictures on the net and dead right, only way to control power output level is by changing the input level from the amp. I don't think there's many amps around that allow more than around + or - 10db on the output level to the Sub?
Not ideal unless run through a separate pre-amp with greater level control.



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  Reply # 748231 21-Jan-2013 14:59 Send private message

B1GGLZ:
Wills1:

Hi There, That's right the only controls on the Sub itself are auto on. on/off and polarity. as well as a voltage selector.


Interesting! I found some pictures on the net and dead right, only way to control power output level is by changing the input level from the amp. I don't think there's many amps around that allow more than around + or - 10db on the output level to the Sub?
Not ideal unless run through a separate pre-amp with greater level control.


Thank you, So is it safe to run the Sub at +10Db? I'm assuming its ok as it has its own power supply, so I imagine its not drawing power from the receiver. But I jst want to make sure I'm not going to damage it.

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  Reply # 748240 21-Jan-2013 15:16 Send private message

Wills1:
Thank you, So is it safe to run the Sub at +10Db? I'm assuming its ok as it has its own power supply, so I imagine its not drawing power from the receiver. But I jst want to make sure I'm not going to damage it.

Don't see why not. It probably has in-built limiting to prevent self destructing.


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  Reply # 748278 21-Jan-2013 16:10 Send private message

So you're running your sub at full volume at all times?
Music, movies, games and TV?
Probably not ideal from a listening point of view...



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  Reply # 748282 21-Jan-2013 16:16 Send private message

Dunnersfella: So you're running your sub at full volume at all times?

Music, movies, games and TV?

Probably not ideal from a listening point of view...


No, I had it set at +2, but as I said the auto cal function set the volume at +10 so I just wanted to make sure it was doing no damage

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  Reply # 748590 22-Jan-2013 07:41

 
Looking at the receiver manual the only crossover options are Front, Center, surround, and Front high speakers crossover. No option for the Sub.


All of those crossover options are for the sub.
The crossover frequency is the frequency that the receiver starts to divert power to the sub as it will do a better job than the main speakers. Your Kef's should provide a reasonable bass output. You would typically set your crossover to something like 80 to 120Hz. If set at 120Hz for your fronts then any frequency content below 120Hz destined for the fronts will be diverted to the sub by the receiver.

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  Reply # 748645 22-Jan-2013 09:45 Send private message

In regards to crossover...
Be aware that when you set your sub to be active over 100Hz the bass will become directional (you'll be able to hear where the sub is, rather than the sub just blending in to the room).
For music I prefer 50Hz as a guideline, and for movies around 80Hz. However, remember these are just guidelines as the performance of your kit will vary from room to room, with placement etc etc. One of the most bloated over driven systems I've heard in a while had set a dual sub setup at 160Hz (one 12" sub was corner loaded at the front left, one behind the listening position) - when we watched Jaba The Hut speak during Star Wars, it sounded like he was sitting in the left hand corner of the room, as the subs were dipping down into the range of the male baritone.

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