Hooking up Jbl hti 88 with denon dvr 486

[m8cook]

I have a denon dvr 486 receiver and 4 boston acoustics 460 and dsi 453 as center and 2 vri 553 in the ceiling and am using a JBL HTI 88 for the sub. I have the sub hooked up to the left and right front channels with the right and left fronts hooked up through the subwoofer. It seems that the sub is not getting power. Can anyone suggest what the problem is and a solution, which recognizes that it has already been wired in the walls so a solution that would not require cutting more holes in the walls?

Thank you in advance

[Luvin Da Blues]

I'm not familar with the JBL HTI 88 is it a passive sub? Are the fronts set to large? If not the receiver won't send any low freqs to the fronts. Hope this helps

[m8cook]

Thank you for the response. The fronts are set to large and yes the JBL HTI 88 in wall sub is a passive-Sub...

[Luvin Da Blues]

Oh buy the way, welcome to this forum.

Don't want to insult you but I have a couple more basic questions. What trouble shooting steps have you already taken.

Has this setup ever worked or is it a new install? I assume that the phasing is correct?
I see that this is a dual driver sub, is it wired for stereo subs or dual mono...there may be a jumper or a switch of some kind to run it mono/stereo..you may have to remove it from the wall. Highly unlikely both drivers would be blown but have you done a continuity/impedance test on the sub(s)?

[m8cook]

Oh you are definately not insulting me. I am a beginner with the whole installation process. To be honest there may be nothing wrong, I have previously had a powered sub so maybe I am just thinking it should sound more like that.

I don't know if it is wired for stereo or dual mono. I have it wired with speaker wire and the sub is connected to the left and right front channel outputs on the receiver and then the right and left from channel speakers are connected to to the sub. The sub is working, but is not producing the deep base I am used to with a powered sub and I saw a posting where someone mentioned that a separate amp was required so maybe I am just paranoid that it needs separate power. Also, by the way what is the difference between stereo and mono in a sub? I am sure it is not blown because it is working. Also, how do you do a continuity/impedence test? Thank you for your help and sorry I am such a novice at this.


Has this setup ever worked or is it a new install? I assume that the phasing is correct?
I see that this is a dual driver sub, is it wired for stereo subs or dual mono...there may be a jumper or a switch of some kind to run it mono/stereo..you may have to remove it from the wall. Highly unlikely both drivers would be blown but have you done a continuity/impedance test on the sub(s)?

[Luvin Da Blues]

Don't wanna be the bearer of bad news but....

Lookin at the specs, I would say that if your down -6db at 30hz and your receiver is rated for 75wpc (and this is "split between the mains and the sub) your not gunna get the deep bass that you would with a powered sub.

Two options..pic up a more powerful amp (even a stereo amp that can be "bridged to mono) dedicated just for the sub or get a stand alone powered sub.

My first foray into Home Theater had a passive sub (configured like your setup) that was a complete wimp too.


# Frequency response 30Hz – 100Hz (–6dB)
# Maximum Recommended Amplifier Power 250 Watts per Channel
# Impedance 8 Ohms nominal per Woofer
# Sensitivity 94dB (2.83V/1m), both woofers driven
# Crossover Frequency 100Hz, 2nd order
# Woofer Dual 8" polymer-coated aluminum cones w/rubber surrounds

[Luvin Da Blues]

Also, by the way what is the difference between stereo and mono in a sub? I am sure it is not blown because it is working. Also, how do you do a continuity/impedence test? Thank you for your help and sorry I am such a novice at this.


No such thing as a dumb question, only dumb answers.

If it's hooked up in stereo each driver would be connected to only one channel thus you would have a sub driver for each channel...with mono (you'd feel lethargic..just jokin) both drivers would be hooked up to both channels and output both the left and right channels together. Since low freqs are pretty much omni directional a mono sub should suffice.

A continuity test is done with a ohm meter to determine is there is a complete path in the circuit ie; no broken wires or burnt out voice coil.

Cheers

EDIT: I assume that you have assured that the positive terminal on the receiver is connected to the positive terminal on the sub for both channels (phasing), if not you will get acoustical cancellation and reduce the overall output.

[m8cook]

Thanks a lot, that was very helpful. I think I will stick with the current set up and explore a power amp for the sub at a later date. Question: If you have a separate amp to drive the sub and from channel speakers how does this integrate with the mid, center and rear channels, which are driven by the receiver?

Thanks....

[Luvin Da Blues]

Thanks a lot, that was very helpful. I think I will stick with the current set up and explore a power amp for the sub at a later date. Question: If you have a separate amp to drive the sub and from channel speakers how does this integrate with the mid, center and rear channels, which are driven by the receiver?

Thanks....

Well, you would run your fronts to the receiver, like you have your center and surrounds and connect your subs' amp to either the pre-outs or even better, if you have it, to the sub RCA out on the receiver. Sounds like you may have to rewire tho. This is where you may wanna consider a separate powered sub and leave everything else as it is. I was just given a Klipsch RW-8 powered sub (used in my home office system) that is quite impressive for a 8" sub and I think they're inexpensive :0:

[m8cook]

Quick question, if I has to get a better receiver such as denon avr-4306, which is 130 watts per channel. Would this help my bass situation. Would the difference be noticeable enough to justify the cost. Thank you in advance...

[Luvin Da Blues]

Quick question, if I has to get a better receiver such as denon avr-4306, which is 130 watts per channel. Would this help my bass situation. Would the difference be noticeable enough to justify the cost. Thank you in advance...

That 4306 is a nice unit but won't change the freq response of your subs..the Built In sub(s) would probably be OK for the upper bass tho (and leave them wired the way they are), which would allow you to set the crossover point a little lower.

It basically takes 10 times the power to double the sound output. If it's deep bass you want I would spend that money on a powered sub (with at least a 250 watt built in amp) that has a decent output to 20Hz or lower...I would do some research within your budget for the best deal.

There has been a lot of threads on this forum about the best subs vs $$$...you should do a search for "subs". :)