4 Q's about the ti500.4

[MORTIS]

1; I'm planning on using the lpl44 with the amp and I know it adjusts input sensitivity/gain but was wondering how it works in conjunction with the sensitivity control on the amp. For example, If I were to set the amp gain controls to max and then hook up the lpl with it set below max, would the gain increase even more if I turn up the lpl or would it make no difference because the the amp is already at max?
Or does it somehow bypass the amp controls whereby the actual gain level is based solely on the position of the lpl knob?

2; If you have all 4 channels set for lp, does the lpl then work on all 4 channels or just the rear?

3; What are the 3 red led's for inside the left side window? The manual talks about the 2 in the right side window but nothing about the 3 on the left.

4; What do all these numbers inside the amp tell about the amp? I'm guessing the "2000" means it was built in 02.

[joyride]

I believe that the LPL adjusts bass boost, not sensetivity. I think that it affects the entire 4 channels of the amp, an not just the rear. As for the pther questions, I have no idea. The number looks like some sort of part number from the OEM.

[HoseHead]

From an SQ perspective:

1. You should NOT have your amp's gain (Sens) control set to max. If the "upstream" signal is properly adjusted to meet the amp's input, then amp gain set to around 60-70% is preferred.

The LPL adds up to 20db of volume to the low pass (LP) output frequencies AFTER the internal crossover. The internal crossover frequencies are determined by the position of the "Freq" potentiometer. The LPL allows you to increase those frequencies ONLY. The "Sens" pot will affect ALL frequencies, including LPL.

You can also adjust "Bass" for front or rear. There's three adjustments to tweak, HU, Bass and LPL, so it's best to have them set near centre so you have adjustments in either direction. I usually set my HU flat and set up the processors to my liking.

2. I've not tried it, but I would say yes the LPL will affect all 4 channels, regardles of whether they are set to LP mode or not. Again, LPL adds up to 20db of volume to LP frequencies and those LP frequencies are determined by the "Freq" pot.

3. The three Red LED's in the left window indicate all is good. Watch the sequence during a power up. Thermal & Overload first, then the Triangle and left side LED's once self test proves servicable.

4. I suggest that circuit board is Revision B of PG Part number 6000.0165 that was originally engineered in the year 2000. I'm not a PG numbers kinda guy.

I did link them manuals to you in another post, didn't I? They're all available from the Sticky in this Section. Ti500.4 Manual

HH

[MORTIS]

Thanks guys!

Joyride, i believe you're right that the lpl adjusts bass boost, or as the manual puts it, lp only. It's intended as a remote sub volume level. I just wasn't sure if it effects all 4 ch if all are set to lp.

Hosehead, i just got it installed yesterday and haven't had a chance to make any fine adjustments yet, but currently the HU sub out and bass eq are both set at just over half way (+1) and the amp gains are at max, which is how I had the previous amp set, and that was half the rms power of the Ti.
At this point, the bass level is the way I prefer it. However, are you saying that I should raise the sub out level a few notches and lower the amp gains respectively which should maintain the current sub volume but also improve SQ?

Regarding your answer; "The LPL adds up to 20db of volume to the low pass (LP) output frequencies AFTER the internal crossover."
Does this mean the lpl controls some sort of small pre-amp that boosts the lp frequencies?
For that matter, if it does control a small pre-amp, then if the lpl is not plugged in then what would be the default setting level of that small pre-amp?

[stipud]

Hold on a sec.

The LPL does not affect bass boost, it reduces amp sensitivity on any channel configured to use lowpass. Basically, it lets you turn down the volume of any subwoofers connected. If you have your front and rear channels configured for low pass, then it will reduce the volume of both. If only your rear channels are set to low pass, then only that volume will be reduced.

If you want to use the LPL to increase the volume, you would have to set your gains above where they should be, then use the LPL to turn it down. This can be dangerous however, because adding too much sensitivity could drive the amp into clipping. Therefore, it must be used responsibly.

[MORTIS]

Thanks Stipud
I'm probably using terms too loosely here. I realize it doesn't affect the 'bass boost' feature in the amp.
Since I'm using all 4 channels set on LP to power 2 DVC subs, I intended to use the LPL to attenuate the bass up or down a little to suit different recordings. The amp is therefore only powering the bass signals in my system so I erroneously said the LPL adjusts bass boost. My mistake.

What you are saying does however make wonder if I will be able to safely make use of the LPL, mainly because I was having to set the gains rather high to get the amount of bass I want from the 8" subs, and when I tried the LPL, I then had to raise the gains even more to give the LPL a useful margin of bass attenuation; which as you say, could risks driving the amp into clipping.

Do you think it would be ok for the HU if instead I raised the sub out volume so that I can keep the amp gains at a safer level? I normally keep the sub out between -1 to +1 to adjust for different music, but if you think it would be safe without affecting SQ if I set the sub out near it's max, then I could give that a try.

Thanks for your help

[stipud]

The HU subwoofer volume control basically does the same thing as an LPL. When you set volume to -3 dB, you are reducing the voltage sent to the amplifier by half. This in turn will make the amplifier play quieter. The LPL does this, but at the amp, so you still have a high voltage input signal making it that far. This way you get a lower noisefloor, while still being able to control the volume level of the amplifier.

I would not recommend boosting the headunit signal beyond 0. In most cases I have only seen this cause horrible distortion and clipping.

Thanks Stipud
I'm probably using terms too loosely here. I realize it doesn't affect the 'bass boost' feature in the amp.
Since I'm using all 4 channels set on LP to power 2 DVC subs, I intended to use the LPL to attenuate the bass up or down a little to suit different recordings. The amp is therefore only powering the bass signals in my system so I erroneously said the LPL adjusts bass boost. My mistake.

What you are saying does however make wonder if I will be able to safely make use of the LPL, mainly because I was having to set the gains rather high to get the amount of bass I want from the 8" subs, and when I tried the LPL, I then had to raise the gains even more to give the LPL a useful margin of bass attenuation; which as you say, could risks driving the amp into clipping.

Do you think it would be ok for the HU if instead I raised the sub out volume so that I can keep the amp gains at a safer level? I normally keep the sub out between -1 to +1 to adjust for different music, but if you think it would be safe without affecting SQ if I set the sub out near it's max, then I could give that a try.

Thanks for your help

[MORTIS]

^ I’m sure you know more about this than I do. It is odd though – I got the Ti to replace my Clarion APA4162 which was 40rms x 4 @4ohms, and I’ve hooked up the Ti the same way and figured I’d be able get more sound pressure with the Ti. I ran the Clarion with the gains at max for years and the amp performed flawlessly and never got more than slightly warm in temperature. The bass it played in my tubes sounded very tight, clean, and smooth. I received many compliments on the SQ of my system.

I do however want to heed your advice since I do value the Ti’s health more than the Clarion.
So do you think if I were to reduce the HU eq bass and treble a few notches and keep the sub out and amp gains at a moderate level, I would then be able to raise the system volume enough to get the bass sound pressure I’m wanting?

Also, I’ve only run the new amp install briefly a few times now, and I live where the current season temperature is around ‘0’ Cels, and after only about 5 minutes with the system on, the fan was running at slow speed. The amp itself still felt ice cold to the touch. Are these fans supposed to run all the time regardless of amp temp? I thought they were activated by a thermostat only when it got hot.

Thanks again

[joyride]

ah, sorry 'bout the wrong info...I never really used one as I have my bass cube and never really thought about it. Although your explination makes way more sense stipud...

[stipud]

Bass boost and cranked gains are the main enemies of amplifiers. For every 3db of boost you add, you are requesting double the power from the amplifier at that frequency. Also, a sensitivity/gain knob is made to match your input frequency (RCAs from the headunit) to the inputs of the amp. If you internally removed the preamp of your amplifier, it would be set up to play it's maximum output at around 8 volts input signal. This means your headunit would have to put out 8 volts RMS, and very few of them can actually do that.

A preamp acts to boost the low voltage headunit output, up to the expected input level of the amplifier. This is what the sensitivity knob adjusts... it tries to convert your 2 volt headunit signal into an 8 volt one, so that the amplifier can play at full volume. However, if you crank the gains, you are telling the amp to be sensitive to 0.2 volts instead of 2! This means it will try to boost the voltage by much more. This could cause signal clipping, which kills amps and speakers alike.

Now I am guessing with your gains cranked on the Clarion, you probably didn't use all of your headunit volume knob? Ideally you want to have at least 3/4 range on your headunit, because that means you get the highest possible output voltage... more voltage means better noise isolation, means better sound quality. Now if you keep turning your headunit up, and it becomes painful distortion... you are probably clipping! If you had sufficient power, then the amp would just keep turning up and it would still sound crystal clear.

So to set your amp up, disable your EQ and everything.. check out the How-To section for "setting your gains via DMM". With a multimeter, you can ensure that your preamp is properly ramping up the voltage, and you are getting the full rated power out of the amplifier, without clipping, at maximum headunit volume. This is the ideal situation.

Another thing worth mentioning is how to properly tune an EQ... If you find that you want more bass in a track... what do you do? Boost the bass? NO!! Reduce your treble and midrange instead. Reducing a signal will never cause harm to an amp, but boosting creates artificial distortion, and asks for too much power from the amp.

^ I’m sure you know more about this than I do. It is odd though – I got the Ti to replace my Clarion APA4162 which was 40rms x 4 @4ohms, and I’ve hooked up the Ti the same way and figured I’d be able get more sound pressure with the Ti. I ran the Clarion with the gains at max for years and the amp performed flawlessly and never got more than slightly warm in temperature. The bass it played in my tubes sounded very tight, clean, and smooth. I received many compliments on the SQ of my system.

I do however want to heed your advice since I do value the Ti’s health more than the Clarion.
So do you think if I were to reduce the HU eq bass and treble a few notches and keep the sub out and amp gains at a moderate level, I would then be able to raise the system volume enough to get the bass sound pressure I’m wanting?

Also, I’ve only run the new amp install briefly a few times now, and I live where the current season temperature is around ‘0’ Cels, and after only about 5 minutes with the system on, the fan was running at slow speed. The amp itself still felt ice cold to the touch. Are these fans supposed to run all the time regardless of amp temp? I thought they were activated by a thermostat only when it got hot.

Thanks again

[MORTIS]

Much thanks Stipud! I appreciate the time you've taken to reply in this thread.
I will try to apply as much of your suggestions as I am able.

I generally ran my head unit volume around half way while the Clarion gains were at max. I probably should have gone for the 10" tubes, as they would likely produce much more sound pressure per amp watt; then I wouldn't be cranking everything so much, but I went with the 8" because they are so very tight and musical - crystal clear bass notes.
Even though my Clarion HU puts out 4 volts I should probably check the incoming voltage at the amp since I'm using as much as 18 - 20 feet of RCA cable and then they are split to the 4 channels

Do you know anything regarding my last question about the amp fan?

Thank you

[stipud]

Do you know anything regarding my last question about the amp fan?

Yes, the fan always runs. It varies speed depending on how hard you work the amp. It would be nice if the fan controller was smart enough to only turn on when you are playing music!

[MORTIS]

What! "It would be nice if the fan controller was smart enough to only turn on when you are playing music."
Are you saying the fan runs all the time, even when you're not playing music? Even when the HU is off while the car is running?

[stipud]

What! "It would be nice if the fan controller was smart enough to only turn on when you are playing music."
Are you saying the fan runs all the time, even when you're not playing music? Even when the HU is off while the car is running?

No, but if your HU is on and muted, it will still spin.

[MORTIS]

OK, that's what I was hoping you'd say. I can live with that I guess.
However, with the fan running every time you turn on the HU, its likely to be the first thing to wear out in the amp.
You're right though, it would be better if it was smart enough to run only when things heated up.

Thanks again for all your help Stipud. I'll post a pic of the setup soon.