Sub with no pre-outs?

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wrencher_25

Copper - Posts: 101

Joined: March 23, 2003

Location: Canada

Posted: April 01, 2003 at 12:20 PM / IP Logged

Well, First of all drvnbysound - If you even READ my message all the way through, I said that I was still new to the industry.

If you really want to know about my full backround - I am still only 18 years old. I just spent (all in all) $9000 going to school in Toronto for a mere two months at the ONLY fully ACCREDITTED school car stereo school in North America. Now, I am MECP Basic Installer Certified. I am also MECP First Class Installer certified but I havn't even worked a full year yet. Anyone can have a piece of paper that says they're MECP certified. It doesn't mean that they are experienced installers. If you're worried about me going and giving crap replies to ppl, I don't reply to everything, just things that I know or have an idea on. Esmith69 for eg, seems to be very knowledgable on this site and has a lot of good responses. So before you start making judgements on people why don't you find out their full backround and where they're at in there career. OK? OK.

ANDREW

Velocity Motors

Moderator - Posts: 12,488

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Joined: March 08, 2002

Location: Manitoba, Canada

Posted: April 01, 2003 at 12:30 PM / IP Logged

Well represented Andrew & thanks for keeping your head on straight. All of us installers ( at least once or twice in our careers) will run into criticism & confrontations with customers or even other installer's. Nobody knows everything about all aspects of the 12 volt industry and everyone is entitled to their opinions. The best thing you can do is take the criticism and learn from it. Please keep in mind that if you are going to be criticizing a another member's techniques or project on this forum, that you keep the criticism contructive and something for the member to use as a tool to get bettter..... NOT to trash talk someone or rip his/her project apart.

Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA

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wrencher_25

Copper - Posts: 101

Joined: March 23, 2003

Location: Canada

Posted: April 01, 2003 at 12:36 PM / IP Logged

I completly agree. I just didn't find that critisism constructive at all. I find that poking at someones credentials (especially when they've worked their asses off for it) is something that I don't take lightly. And I know that I am still new, and I am VERY willing to learn and have a sheer passion for this industry. I love every minute of my job. It's keeping the critisism constructive and try to say it nicely...b/c lets face it, no one likes to admit their wrong. I think that critisism should me made about the topic, not the person. Thanks for the input Velocity Motor.

Andrew Weitzel

MECP First Class Installer

Velocity Motors

Moderator - Posts: 12,488

Joined: March 08, 2002

Location: Manitoba, Canada

Posted: April 01, 2003 at 12:53 PM / IP Logged

No problemo Andrew.... good luck with the career of a mobile installer.

Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA

dragonrage

Copper - Posts: 193

Joined: March 15, 2003

Location: United States

Posted: April 01, 2003 at 12:56 PM / IP Logged

Did you end up getting a high to low converter? I've had some people criticize the way I mentioned but there's nothing wrong with it. It's cheap (under $1), it takes up almost no room, and it's simple. Some people on here have said that it's improper and to spend the money to get a real high to low converter, but they just don't know how it works. The other way it could be done is using an op amp and the formula: gain = Rfeedback / Rin. But for an opamp you'd need a DC offset to not need to use the negative voltage supply. So if you haven't gotten a high to low converter, I'd use the original circuit I posted. I use it now and it works. Though as my sig says I'm getting a new CD player soon anyway :)

2009 Pontiac G8 in planning stage

HU: ?

Speakers: ?

Amps: ?

wrencher_25

Copper - Posts: 101

Joined: March 23, 2003

Location: Canada

Posted: April 01, 2003 at 1:55 PM / IP Logged

Dragonrage...

Your way looked really interesting (using resistors) and would make a lot of sense. The buddy I took school with recommended the same thing but we didn't know the right values of resistors. The prob is...i don't know the power rating of the amp that I have. (I bought it used unfortunately) But it does have a "HI input" and I was thinkin bout just soldering directly to the pins. But if you know the rating of the amp then maybe you could help me with the resistance values. I would actually like to know how to calculate those values if you don't mind. But the model of the amp is a Pheonix Gold QX 2180. I don't know the power ratings or ANY of the specs which makes things difficult. Thanks for the help too!!!

Andrew Weitzel

MECP First Class Installer

dragonrage

Copper - Posts: 193

Joined: March 15, 2003

Location: United States

Posted: April 01, 2003 at 7:27 PM / IP Logged

Well, you don't need exact values. But I will show you how I came up with those.

Formulas used: P = V^2/R, voltage divider

So using the above formula, if you had a 40W/chan deck,

40 = V^2 / 4

160 = V^2

V = 12.65

So you have 12.65 volts peak out

If the top resistor on my schematic before is R1 and the bottom is R2 and we'll call the voltage at the amp Vamp

Vamp = Vdeck(R2/(R1+R2))

Vamp = 12.65(1/11)

Vamp = 1.15V

Note that you don't NEED about 1V, most amps go down to about .25V, and up to at least a few volts. You can play around with the values as needed.

2009 Pontiac G8 in planning stage

HU: ?

Speakers: ?

Amps: ?

drvnbysound

Silver - Posts: 289

Joined: May 06, 2002

Location: United States

Posted: April 01, 2003 at 10:58 PM / IP Logged

I wanted to take the time and apoligize for my previous post. I did not intend for you to take it as as I "poking fun" at you. I have been in the industry going on 5 years now, and you are the first person I have come across who is MECP certified and was unfamiliar with LOC's. I, as most people I know, got into the business by installing equipment in their personal cars, and friends cars, before attempting, or even thinking about taking the MECP test.

Personally, I am an Electrical Engineering major at Florida State University. Currently, with the help of a friend, about to open a stereo shop here in Panama City, FL. Odd thing, is that I have not even taken the MECP test personally, nor have I flipped through the pages of the study guide. However, I have previously worked at various shops, doing everything from custom fiberglass enclosures to mobile video systems, and whatever else I was called upon to do. I have the understanding of how most mobile electronics products work, though my studies as an engineer. Once again, just seemed strange to me, that you were MECP certified and had the lack of hands on experience with the acutal products. Again, I apoligize for my previous post.

wrencher_25

Copper - Posts: 101

Joined: March 23, 2003

Location: Canada

Posted: April 01, 2003 at 11:48 PM / IP Logged

To be perfectly honest.....I am MECP certified but still within the first weeks of my working experience....school trained me well for that test but I know that it means nothing until you have the hands-on-experience. There are a lot of ppl out there more skilled and trained and it will only take time before I gain that experience and will really be able to call myself "elite" or a "master" installer. It all takes time.

But enough about that.....lets get back to what's important.....and that's car audio.

Andrew Weitzel

MECP First Class Installer

wrencher_25

Copper - Posts: 101

Joined: March 23, 2003

Location: Canada

Posted: April 01, 2003 at 11:50 PM / IP Logged

Thanks a lot dragonrage.....i'll keep that one handy and play with some figures. I know some decks are 50W/Channel and so on.....i get it now. Thanks so much.

Andrew Weitzel

MECP First Class Installer

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