No remote adjustment?

[lliamiskool]

Hi all. I recently bought a used Jensen Power 900.1 amp. I wired it to a 24 year old 12" MTX 250 watt 4 ohm sub. The main issue is that the remote adjustment knob doesn't adjust anything. When I plug that wire into the amp, its a bit loose but even when I push it in it does nothing. Secondly, I'm not too sure on how to tune it. I know to set the bass boost to 0db but I'm not sure what I should set the subsonic (10hz-40hz), low pass (40hz-300hz), or the level (4v-0.4v). Any advice would be much appreciated. Thanks!

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[Doxquzme Premium Member]

Could be the cable. That knob is essentially a volume boost. Could be it requires a 6-point contact RJ11 instead of a 4 [in. The main difference between RJ11 vs. RJ45 connectors is the size and the number of wires they are used to carry. Registered Jack-11 has 6 pins, but typically only 4 of them are used. Due to their size, they are most commonly used for telephone, fax machines, and low-speed networking applications.

If that fails to work could use one of these inline which will require the use of an additional RCA cable. It's thick plastic but I've purchased one and the potentiometer knob is nice.

Amazon product ASIN B0795C68CV
When using filters, keep this in mind. the high or the low is what is "passing". A low pass filter allows a low frequency to pass, a high pass, highs to pass, etc. A subsonic filter is actually a high pass filter for the low end of the frequencies output from the amp, it only allows higher (than) frequencies to pass, in this case, anything above 20-40Hz which prevents anything lower than the frequency selected to pass. The settings take into account two things, the subwoofer frequency response both high and low relative to the other speakers' settings in the group. Most car speakers don't play down below 60hz effectively. Subs frequency filters are set to take care of the frequencies that the mains do not handle. In most cases, there is a slight, desirable overlap in the 70-100 hz area. The THX settings usually call for (and which is generally accepted in car audio too) 80Hz as the top frequency output for the subs, so try setting the amp to between 80-100hz, listen to it on a couple of tracks, different music genres, decide what sounds best, art, not science here. I don't know what your subs play down to and that decides what to set the subsonic filter at. 20 to 30hz is the norm, start there and give it a listen.

As for the BASS boost, that is a level adjustment for a specific or fixed band of frequencies. On this amp, it is 45hz, specifically. Control info from the Jensen manual:

BASS EQ (boost)
The Bass EQ is continuously adjustable from 0 to +12dB @ 45Hz. Adjusting
the Bass Boost level allows different subwoofer/enclosure combinations to be
equalized. Use this control to increase the level of low bass available from your
subwoofer/enclosure combination. Ported and Band Pass enclosures should
be limited to about +6dB to +9dB of boost. Sealed enclosures should be able
to accept the full +12dB of boost, if necessary. The full +12dB of boost should
be reserved for special applications since improper use of the Bass Boost
could damage your subwoofers at high volumes.

Low Pass Filter (LPF)
The Low Pass Filter controls adjust the crossover point. The typical crossover point is
between 60Hz and 80Hz for ported and sealed enclosures. Bandpass boxes
will typically use a higher crossover setting between 125Hz and 150Hz. Since
musical tastes vary, you should play music that you would normally listen to in
your vehicle, with the above settings as a starting point. If necessary, set the
crossover by ear.

High Pass Filter (HPF)
The high pass filter will limit the low frequencies being transmitted to your
speakers. This can be useful in a number of situations. For example, if you
selected the high pass filter and set the crossover to 40Hz, then you would
have an infra-sonic (sub-sonic) filter at 40Hz, which would be useful with
certain enclosure/subwoofer combinations that were tuned between 45Hz and
50Hz. Other uses might include limiting the low frequencies to smaller
speakers (6 1/2", 6 X 9", etc.) by adjusting the crossover to a higher setting
(80–100Hz).

 

[lliamiskool]

Could be the cable. That knob is essentially a volume boost. Could be it requires a 6-point contact RJ11 instead of a 4 [in. The main difference between RJ11 vs. RJ45 connectors is the size and the number of wires they are used to carry. Registered Jack-11 has 6 pins, but typically only 4 of them are used. Due to their size, they are most commonly used for telephone, fax machines, and low-speed networking applications.

If that fails to work could use one of these inline which will require the use of an additional RCA cable. It's thick plastic but I've purchased one and the potentiometer knob is nice.

Amazon product ASIN B0795C68CV
When using filters, keep this in mind. the high or the low is what is "passing". A low pass filter allows a low frequency to pass, a high pass, highs to pass, etc. A subsonic filter is actually a high pass filter for the low end of the frequencies output from the amp, it only allows higher (than) frequencies to pass, in this case, anything above 20-40Hz which prevents anything lower than the frequency selected to pass. The settings take into account two things, the subwoofer frequency response both high and low relative to the other speakers' settings in the group. Most car speakers don't play down below 60hz effectively. Subs frequency filters are set to take care of the frequencies that the mains do not handle. In most cases, there is a slight, desirable overlap in the 70-100 hz area. The THX settings usually call for (and which is generally accepted in car audio too) 80Hz as the top frequency output for the subs, so try setting the amp to between 80-100hz, listen to it on a couple of tracks, different music genres, decide what sounds best, art, not science here. I don't know what your subs play down to and that decides what to set the subsonic filter at. 20 to 30hz is the norm, start there and give it a listen.

As for the BASS boost, that is a level adjustment for a specific or fixed band of frequencies. On this amp, it is 45hz, specifically. Control info from the Jensen manual:

BASS EQ (boost)
The Bass EQ is continuously adjustable from 0 to +12dB @ 45Hz. Adjusting
the Bass Boost level allows different subwoofer/enclosure combinations to be
equalized. Use this control to increase the level of low bass available from your
subwoofer/enclosure combination. Ported and Band Pass enclosures should
be limited to about +6dB to +9dB of boost. Sealed enclosures should be able
to accept the full +12dB of boost, if necessary. The full +12dB of boost should
be reserved for special applications since improper use of the Bass Boost
could damage your subwoofers at high volumes.

Low Pass Filter (LPF)
The Low Pass Filter controls adjust the crossover point. The typical crossover point is
between 60Hz and 80Hz for ported and sealed enclosures. Bandpass boxes
will typically use a higher crossover setting between 125Hz and 150Hz. Since
musical tastes vary, you should play music that you would normally listen to in
your vehicle, with the above settings as a starting point. If necessary, set the
crossover by ear.

High Pass Filter (HPF)
The high pass filter will limit the low frequencies being transmitted to your
speakers. This can be useful in a number of situations. For example, if you
selected the high pass filter and set the crossover to 40Hz, then you would
have an infra-sonic (sub-sonic) filter at 40Hz, which would be useful with
certain enclosure/subwoofer combinations that were tuned between 45Hz and
50Hz. Other uses might include limiting the low frequencies to smaller
speakers (6 1/2", 6 X 9", etc.) by adjusting the crossover to a higher setting
(80–100Hz).

Wow, that was extremely helpful. Thank you!!

 

[RobGMN 5,000+ posts]

He nailed it. Might as well close the thread, lol.

 

[audiobaun 5,000+ posts]

He nailed it. Might as well close the thread, lol.

Could be the cable. That knob is essentially a volume boost. Could be it requires a 6-point contact RJ11 instead of a 4 [in. The main difference between RJ11 vs. RJ45 connectors is the size and the number of wires they are used to carry. Registered Jack-11 has 6 pins, but typically only 4 of them are used. Due to their size, they are most commonly used for telephone, fax machines, and low-speed networking applications.

If that fails to work could use one of these inline which will require the use of an additional RCA cable. It's thick plastic but I've purchased one and the potentiometer knob is nice.

Amazon product ASIN B0795C68CV
When using filters, keep this in mind. the high or the low is what is "passing". A low pass filter allows a low frequency to pass, a high pass, highs to pass, etc. A subsonic filter is actually a high pass filter for the low end of the frequencies output from the amp, it only allows higher (than) frequencies to pass, in this case, anything above 20-40Hz which prevents anything lower than the frequency selected to pass. The settings take into account two things, the subwoofer frequency response both high and low relative to the other speakers' settings in the group. Most car speakers don't play down below 60hz effectively. Subs frequency filters are set to take care of the frequencies that the mains do not handle. In most cases, there is a slight, desirable overlap in the 70-100 hz area. The THX settings usually call for (and which is generally accepted in car audio too) 80Hz as the top frequency output for the subs, so try setting the amp to between 80-100hz, listen to it on a couple of tracks, different music genres, decide what sounds best, art, not science here. I don't know what your subs play down to and that decides what to set the subsonic filter at. 20 to 30hz is the norm, start there and give it a listen.

As for the BASS boost, that is a level adjustment for a specific or fixed band of frequencies. On this amp, it is 45hz, specifically. Control info from the Jensen manual:

BASS EQ (boost)
The Bass EQ is continuously adjustable from 0 to +12dB @ 45Hz. Adjusting
the Bass Boost level allows different subwoofer/enclosure combinations to be
equalized. Use this control to increase the level of low bass available from your
subwoofer/enclosure combination. Ported and Band Pass enclosures should
be limited to about +6dB to +9dB of boost. Sealed enclosures should be able
to accept the full +12dB of boost, if necessary. The full +12dB of boost should
be reserved for special applications since improper use of the Bass Boost
could damage your subwoofers at high volumes.

Low Pass Filter (LPF)
The Low Pass Filter controls adjust the crossover point. The typical crossover point is
between 60Hz and 80Hz for ported and sealed enclosures. Bandpass boxes
will typically use a higher crossover setting between 125Hz and 150Hz. Since
musical tastes vary, you should play music that you would normally listen to in
your vehicle, with the above settings as a starting point. If necessary, set the
crossover by ear.

High Pass Filter (HPF)
The high pass filter will limit the low frequencies being transmitted to your
speakers. This can be useful in a number of situations. For example, if you
selected the high pass filter and set the crossover to 40Hz, then you would
have an infra-sonic (sub-sonic) filter at 40Hz, which would be useful with
certain enclosure/subwoofer combinations that were tuned between 45Hz and
50Hz. Other uses might include limiting the low frequencies to smaller
speakers (6 1/2", 6 X 9", etc.) by adjusting the crossover to a higher setting
(80–100Hz).

.lol

 

[audiobaun 5,000+ posts]

He nailed it. Might as well close the thread, lol.

 

[HardofWhoring]

He nailed it. Might as well close the thread, lol.

The remote knob might just be bad. It's not required, so take it out, and set your gain. If you then put it back in (at full), and it does something different, then something is wrong with the knob. Those 3.5mm jacks are always sketchy. You can try a different one, but if it's the connection on the amp, the easier solution would probably be to just get a remote knob that is on the RCA wire. You would wire this inline, so you're most likely going to need another set of RCAs. Then you can mount this where it's convenient. There are several styles. Here are the ones I'm using.
Amazon product ASIN B003FPD3IS
Low pass filter is what frequencies can pass lower than the filter. If you don't know the targeted frequency range for the sub, just set it as high as it can go, 300hz, and everything below 300hz will not be filtered out. You can play with it after that if you have a targeted range, but for a 150w sub, then don't worry about it.

The level (.4v -4v)I don't see a picture, but that should be your gain. It's trying to match it up with your head unit's preout voltage. There are better ways to do this if you have a multimeter. If your head unit has 4v preouts, you set it at 4v, and you're sending out the lowest power that amp can do.
I don't know the specs on your amp, or if that sub is 250w max or RMS but I would suggest instead of that, do it this way to match up with RMS rated power. See how close you can get, and how that works.

 

[metalheadjoe 10+ year member]

He nailed it. Might as well close the thread, lol.

Who let you out of the thunderdome?

 

[RobGMN 5,000+ posts]

Who let you out of the thunderdome?

Lol. I’m free to roam. Apparently unlike whoever got banned for bad behavior.

 

[Doxquzme Premium Member]

Who let you out of the thunderdome?

 

[lliamiskool]

So I tried two different adjustment knobs and neither did anything. I bought an inline adjuster instead. I plugged a short RCA cable into the radio and into the input side of the knob, and plugged in the RCA cables that lead to the amp into the output side. At full adjustment the sub barely worked and anything else the sub did not work. Any ideas?

 

[Doxquzme Premium Member]

How do you have these adjustments configured?

Do we know what the voltage is that the HU is delivering?

 

[HardofWhoring]

So I tried two different adjustment knobs and neither did anything. I bought an inline adjuster instead. I plugged a short RCA cable into the radio and into the input side of the knob, and plugged in the RCA cables that lead to the amp into the output side. At full adjustment the sub barely worked and anything else the sub did not work. Any ideas?

At this point, if you can't even put in any effort in just a thread to help you, you should just take it to a shop.

 

[lliamiskool]

How do you have these adjustments configured?

View attachment 54233

Do we know what the voltage is that the HU is delivering?

I have the bass boost set to 0, low pass set to about 300, level is set to 4V because it is a Boss BE62CP which outputs 4v, and subsonic set to about 25 hz. Thanks

 

[RobGMN 5,000+ posts]

So I tried two different adjustment knobs and neither did anything. I bought an inline adjuster instead. I plugged a short RCA cable into the radio and into the input side of the knob, and plugged in the RCA cables that lead to the amp into the output side. At full adjustment the sub barely worked and anything else the sub did not work. Any ideas?

Your low pass is set way too high.

But that's not the real problem.
The real problem is that you are saying you connected the RCA cables to the amp "output" side of the amp. The verbiage used on equipment regards signal flow.
Keep It Super Simple: If you want the signal to flow IN to the amp from your source, then you connect the RCA cable to the jacks labeled INput.

The OUTput RCA jacks can then be used to send that same signal on to another amp if you are stacking amps.