Amp Remote Turn On & Line level Convertersl

[Gord95]

Hi guys,

Am a newbie to this forum but I feel I've alredy learned a lot just by reading lots of posts.
Amazing the amount of info here!

I need a little help with an install I'm doing on my Miata and am hopeful I can get the benefit of some of your expertise.

Want to keep the stock HU which is really pretty **** good. It is an in-dash 6 CD/AM/FM Changer made for Mazda by Matsushita (Panasonic). Am replacing the door speaker components with some CDT units and also am adding an 8" CDT sub. Unfortunately, thats all the room there is for speakers in this small car.

Powering is through a 4 x 50/100 amp, bypassing the internal amp in the HU. I have two issues I'm not sure about.

A) The stock OEM HU does not have a remote turn on for the amp.

B) The stock OEM HU does not have preamp level outputs so cannot use RCA cables to the amp.

What is the best way to hook up a remote turn on for the amp? I've read posts where guys are going direct to the fuse block and others have wired in a relay. Seems like a relay would be the safest way to go, but being a novice at this, I'm not certain how to do it. Would only want the amp on when the HU is turned on.

I have read that I can purchase line level converters to allow the use of RCA cables to go from HU to the amp and doing so will provide better sound and S/N ratio. It seems this would be the way to go but I have no experience with line level converters. What's a good brand and a good place to buy?

Will be using two channels for the front component sets in the doors, and will bridge the other two channels on the amp to feed the sub. Am I correct that I can use the rear speaker outputs of the HU to feed signal to amp for the sub. The amp has built in adjustable crossovers so I can control Hz going to speakers.

Sorry for this long post. As I learn more, will try to keep them much shorter.

Any and all suggestons and assistance will be most appreciated.


Gord95

[maylar]

The remote for your amp is a low current 12 volt input. If the car has a power antenna, then the HU wire that runs that would work fine. If not, you can run the rem input from any 12v accessory line in the car (on with ignition). And an external switch.

You didn't mention what amp you're using, but some of them have speaker level inputs as well as RCA inputs. Basically, they have line converters built in. If yours doesn't, you can get them at any audio shop and even CircuitCity.

[Gord95]

Thanks Dave for you input.

I am running an Ultimate TA 4320 amp which does have both RCA as well as speaker level input capability. However, I was told that I would get better sound and better S/N if I used line output converters on the HU so I could run RCA patch cords to the amp. ???
Is this true?

As to the remote turn on, I'm not certain yet since I haven't installed it, but I think the HU may retract the antenna whenever I switch from AM/FM to CD. That would probably turn the amp off wouldn't it??

Thanks for any additional help.

[i3abyjay25]

or you can go G-H-E-T-T-O, and take your rca patch cord and cut the male end plugs off of 1 side and run them to the speaker out off the radio.

[maylar]

Originally posted by Gord95
Thanks Dave for you input.

I am running an Ultimate TA 4320 amp which does have both RCA as well as speaker level input capability. However, I was told that I would get better sound and better S/N if I used line output converters on the HU so I could run RCA patch cords to the amp. ???
Is this true?

No. For S/N it'd be the other way around.. it's a lot harder for noise to enter a low impedance speaker wire than a high impedance RCA cable. Sound quality will be the same either way. I'd definitely use the amp's speaker level inputs.

As to the remote turn on, I'm not certain yet since I haven't installed it, but I think the HU may retract the antenna whenever I switch from AM/FM to CD. That would probably turn the amp off wouldn't it??

Yup. That'd ****. If that's the case, you're only option is an external switch.

[Gord95]

Originally posted by maylar
[B]No. For S/N it'd be the other way around.. it's a lot harder for noise to enter a low impedance speaker wire than a high impedance RCA cable. Sound quality will be the same either way. I'd definitely use the amp's speaker level inputs.
Yup. That'd ****. If that's the case, you're only option is an external switch.

Thanks Maylar for the response. I have just found a source, David Navone Engineering, that makes some really good products for car audio, one of which is a remote turn on device that senses very small current to any speaker and uses that to switch on the amp.
So, it looks like that may be the final answer to my issue with the HU not having a line for turning on the external amp.

As to RCA vs speaker line input to the amp, now I've got two differing opinions. The manufacturer of the amp, Ultimate Sound, has advised "it's always better to use a line out converter if your HU does not have preamp outputs, as it will provide better sound and better S/N". Your point seems to contradict this insofar as the S/N issue. ??

Gord95

[Savant]

For the remote turn on.. Is there any reason you don't want to just tap into a 12 v power source and run a switch on that? turn it on when you want your amps on, off when you don't want them on? I would think that would be a much cheaper option than any special hardware, and I wouldn't suggest an antenna line in any event (given the nature of how it 'might' work, like cutting off in CD mode)..

For the RCA/line converters.. From what I understand.. the higher the voltage on the wire the less likely you are to notice any "noise".. the noise is 'low power' but is constant (it's introduced as some current at a certian frequency) so the more power on the wire, the more burried the 'noise' becomes.. If you have the converter up front and run RCAs to the back, the RCAs could pick up the noise, and the amplifier will amplify that as well.. If you run the high level speaker wires to the back, then to a converter, you will probably minimize that..

The only reason I can think of that the manufacture suggests the RCAs over anything else is that you normally have a cleaner base signal on the RCA outputs of a HU cause it's not running through an amplifier (like the speaker outs)... but since they have the high-level in, they realize you might not have that on the HU.. to suggest you convert it external to the amp implies (to me anyway) thier converter isn't that good.. In that case you might want to use one, but like I said, try to keep it as close to the amp as you can..

Hope that helps..

[Gord95]

Originally posted by Savant
For the remote turn on.. Is there any reason you don't want to just tap into a 12 v power source and run a switch on that? turn it on when you want your amps on, off when you don't want them on? I would think that would be a much cheaper option than any special hardware, and I wouldn't suggest an antenna line in any event (given the nature of how it 'might' work, like cutting off in CD mode)..

For the RCA/line converters.. From what I understand.. the higher the voltage on the wire the less likely you are to notice any "noise".. the noise is 'low power' but is constant (it's introduced as some current at a certian frequency) so the more power on the wire, the more burried the 'noise' becomes.. If you have the converter up front and run RCAs to the back, the RCAs could pick up the noise, and the amplifier will amplify that as well.. If you run the high level speaker wires to the back, then to a converter, you will probably minimize that..

The only reason I can think of that the manufacture suggests the RCAs over anything else is that you normally have a cleaner base signal on the RCA outputs of a HU cause it's not running through an amplifier (like the speaker outs)... but since they have the high-level in, they realize you might not have that on the HU.. to suggest you convert it external to the amp implies (to me anyway) thier converter isn't that good.. In that case you might want to use one, but like I said, try to keep it as close to the amp as you can..

Hope that helps..

Thanks Savant. I believe I have a handle on this now thanks to the responses from you guys. Seems as though there are a lot of things that can trip you up on some of these install issues. Thanks again to all that responded.

Gord95

[maylar]

Originally posted by Gord95
Thanks Maylar for the response. I have just found a source, David Navone Engineering, that makes some really good products for car audio, one of which is a remote turn on device that senses very small current to any speaker and uses that to switch on the amp.

Cool. I was thinkin' of inventing one lol.

As to RCA vs speaker line input to the amp, now I've got two differing opinions. The manufacturer of the amp, Ultimate Sound, has advised "it's always better to use a line out converter if your HU does not have preamp outputs, as it will provide better sound and better S/N". Your point seems to contradict this insofar as the S/N issue. ??Gord95

That would be generic advice for running line converters with amps that don't have speaker level inputs. Running your speaker outputs directly into the RCA inputs of an amp will overdrive the hell out of them. The speaker level inputs on an amp so equipped should be exactly the same as what you'd use externally. Unless as Savant says, theirs *****. But I doubt they'd admit that...

[Gord95]

Originally posted by maylar
[B]Cool. I was thinkin' of inventing one lol.
That would be generic advice for running line converters with amps that don't have speaker level inputs. Running your speaker outputs directly into the RCA inputs of an amp will overdrive the hell out of them. The speaker level inputs on an amp so equipped should be exactly the same as what you'd use externally. Unless as Savant says, theirs *****. But I doubt they'd admit that...

Yeah, I agree. I probably wouldn't either if it was a soft spot in one of my products.

Don't know if you're serious about "looking for free air 8's"but it seems to me JL Audio makes some. Like I said, I'm new to this forum so not sure yet when someone is just foolin around.

Gord 95