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#24187 - 09/17/03 09:39 PM Little output from sub?
Nostalgia Offline
Gunslinger

Registered: 07/25/03
Posts: 137
Loc: Lake Hopatcong, NJ 07849
Hey all. I just finished building a vented sub enclosure for my Adire Shiva.

I have a 950/7100 combo. I connected the Sub output from the 950 to one of the unused channel on the 7100. I connected that to the Shiva, whose voice coils are wired in parallel (+ to + and - to -).

The thing is, I don't think I'm getting the output I should from it. When calibrating my speakers using the internal test tone, all of my speakers calibrate to 75db at -9db, give or take. Even when I crank the sub up to +10db, I don't hear more than a hum. I feel a rumble, but not nearly the output I'd expect at reference level.

To verify this, I tried the same thing with Avia's test DVD, and achieved the same result.

I have my mains set to "Small" and the Subwoofer set to "On" in the 950's menus.

Any ideas?

Thanks!

-Joe

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#24188 - 09/17/03 11:13 PM Re: Little output from sub?
bossobass Offline
Desperado

Registered: 08/19/02
Posts: 430
Loc: charlotte, nc usa
Hmmmmmmm...

The Shiva has dual 8 ohm VCs, so parallel wiring makes it a 4 ohm load.

The 7100 is rated at 165 watts @ 4 ohms.

Sensitivity of the Shiva is 87 dB, 1W/1M.

I doubt you'll get ref level bass with this combination.
____________________________________________
The thing is, I don't think I'm getting the output I should from it. When calibrating my speakers using the internal test tone, all of my speakers calibrate to 75db at -9db, give or take.
____________________________________________

What is the main volume set at when you calibrate?

How big is the room?

What source are you playing?

Is the amp distorting when you 'crank it to +10'?

Also, you have no phase adjustment with this setup, and This may have something to do with the apparent anemia. Try reversing the speaker wires to see if there is any volume difference. Use your SPL meter and play a bassful tune, switch the speaker wires, play the same passage and note the SPL reading.
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#24189 - 09/18/03 09:29 AM Re: Little output from sub?
Nostalgia Offline
Gunslinger

Registered: 07/25/03
Posts: 137
Loc: Lake Hopatcong, NJ 07849
boss,

Thanks for the advice. Perhaps I just need a more beefy amp. I was hoping to use the Outlaw until funds arrive to buy a new amp. Where's our high power sub amp, Outlaw?!?

Let me address your questions...

--What is the main volume set at when you calibrate?

Zero. The other channels very easily put out 75db.

--How big is the room?

About 14x18. The sub is right in front of my seating position. I know, no loading, but it's a coffee table. My wife might get upset if I put the coffee table in a corner. "Bad coffee table! Go sit and think about what you've done."

--What source are you playing?

I tried the internal test tones of the 950, and the audio setup tones on Avia's disc. I just retested with Avia. It plays a tone on the main speaker, then the sub. I read 75db on the main speaker, but the sub didn't even register when I set the meter to 60db. I can hardly hear it.

--Is the amp distorting when you 'crank it to +10'?

I don't know. The only thing I push to +10 is the channel trim for the subwoofer channel. Even then, there's not enough audible information to tell if there's distortion. I can feel the sub's vibration through the floor (spiked), and there's air whoofing (I looked that word up) out of the port.

--Also, you have no phase adjustment with this setup, and This may have something to do with the apparent anemia. Try reversing the speaker wires to see if there is any volume difference. Use your SPL meter and play a bassful tune, switch the speaker wires, play the same passage and note the SPL reading.

I just tried this, and it made no discernible difference.

Thanks,

-Joe


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Remember the Intellivision?
http://www.gotmaille.com/nostalgia/

[This message has been edited by Nostalgia (edited September 18, 2003).]
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#24190 - 09/18/03 09:41 AM Re: Little output from sub?
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
Joe

It sounds like the Shiva may still be a bit hungry for power, but also keep in mind the Radio Shack SPL meter's low frequency inaccuracy . This is obviously not the problem that you are encountering (unless you're using a 10Hz test tone, which the 950 certainly doesn't do and I doubt Avia does either ), but it may be useful as you get further along.

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#24191 - 09/18/03 10:19 AM Re: Little output from sub?
bossobass Offline
Desperado

Registered: 08/19/02
Posts: 430
Loc: charlotte, nc usa
More thoughts...what crossover setting have you selected for the main speakers? It sounds like you may have it set low.

You can try setting it higher, say 100 Hz and see if that changes anything.

Though I see now that you can't move the sub/table to a corner, try moving the SPL meter around the room and note any changes. You might at least be able to be sure the sub isn't centered in the room.

You can also try temporarily connecting each VC of the Shiva seperately to 2 channels of the 7100 (Y-jack from the 950's SW out), which will boost your amp power to 2oo watts total.

I agree that you should be hearing more output than you describe.

Make sure the cable from the 950 to the 7100 is good.
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#24192 - 09/18/03 10:39 AM Re: Little output from sub?
Spiker Offline
Gunslinger

Registered: 05/29/03
Posts: 297
Loc: Middle Earth
Joe,
Shiva is a very efficiant driver. Adire Audio mentions itís ability to run efficiantly at 45 watts and handle up to 650 watts. I own one and I canít ask for more considering itís small price tag. Even if it costs more, Iíll still be happy with it.

Dedicated sub amps are not that expensive (unless you want real high power). If you havenít, check out this site: www.acoustic-visions.com/

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#24193 - 09/18/03 10:45 AM Re: Little output from sub?
steves Offline
Desperado

Registered: 06/18/01
Posts: 356
Loc: Oregon
I would suggest going back and checking your internal wiring, Nostalgia. It sounds like you may have inadvertedly cross-wired the voice coils causing an out of phase condition. I believe your 7100 should supply sufficient power for this driver, giving you plenty of output- at least for now! By the way, I have 2 Shivas in sealed enclosures- I like 'em. Good luck!

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#24194 - 09/18/03 10:48 AM Re: Little output from sub?
Nostalgia Offline
Gunslinger

Registered: 07/25/03
Posts: 137
Loc: Lake Hopatcong, NJ 07849
Yes, I did have the xover at 40hz. Raising it to 80hz gives me about 65db from the sub when there's 75db coming from the mains. The subsonics are enough to rattle everything in the house, so I guess I'm on the right track. 80hz seems kinda high to be crossing the sub over, though.

Again, I'm probably more used to the car audio world. My HT sub seems to have more "feel" and less audible material than I'm used to.

Jeff's coming over this weekend, I'll have him give a listen.

Thanks for the suggestions,

-Joe

------------------
Remember the Intellivision?
http://www.gotmaille.com/nostalgia/
_________________________
Man Skirt Brewing Company - No pants, just great beer!

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#24195 - 09/18/03 10:54 AM Re: Little output from sub?
Nostalgia Offline
Gunslinger

Registered: 07/25/03
Posts: 137
Loc: Lake Hopatcong, NJ 07849
Quote:
Originally posted by steves:
I would suggest going back and checking your internal wiring, Nostalgia. It sounds like you may have inadvertedly cross-wired the voice coils causing an out of phase condition.


I'm positive the internal wiring is right. I know this because I wired it wrong at first I've got the two voice coils wired + to + and - to -. I've got the terminal cup wired up red to the + and black to the -. I tried running the speaker wired from my amp both ways, in and out of phase, with no real change in sound.

Raising the crossover seems to have helped. I think I just need a second opinion

-Joe



------------------
Remember the Intellivision?
http://www.gotmaille.com/nostalgia/
_________________________
Man Skirt Brewing Company - No pants, just great beer!

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#24196 - 09/18/03 12:56 PM Re: Little output from sub?
boblinds Offline
Gunslinger

Registered: 02/07/03
Posts: 242
Loc: Los Angeles
Quote:
My HT sub seems to have more "feel" and less audible material


Your "training" in car stereo sound may indeed be the issue here since the "audible" bass you mention would, I think, tend to be in the upper bass range at 80Hz and even higher.

Some of the car stereos I've heard boost this range to create an artificial impact. It's impressive in its way but more bloated than accurate.

Play with an even higher crossover point, just for the heckuvit, and see what you think. It might help you suss out your preferences and tastes.

Then just live with it for awhile. You may just be getting accurate bass for the first time. Good bass isn't flooding all over the map but is solidly, decisively there when you need it.

Have fun!

[This message has been edited by boblinds (edited September 18, 2003).]

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