Nighthawk

I'm beginning to look at the sound system in my '77 cutlass and am exploring all my options. My radio doesn't work, but I like the original look so I am trying to avoid tossing it. I can't fit a new dash unit into my budget So, with that in mind, my current plan is to find an amplifier with an audio jack or usb port which I can plug directly into the speakers. I am hoping to hide this under the dash somewhere. Now the problem is understanding exactly which amplifier will work with my speakers. In the rear I have 6x9 oem speakers from opgi.com. These are rated at 60w/10ohm. I haven't looked at the front speakers, but since they are original I am assuming that they are similar to the rear ones. So what numbers do I need to look at when choosing an amplifier? I found several amplifiers that have the features I want but I don't know if they have the proper watts/ohms. Three of my favorites are listed below:

http://dx.com/p/aluminum-4-channel-d...-golden-197164

http://dx.com/p/lepai-lp-269fs-45w-4...-blacfk-257271

http://www.rakuten.com/prod/boss-rio...220508993.html

Also, I would appreciate clarification as to exactly what the difference is between 2 and 4 channel amplifiers. I'm pretty sure I can hook 4 speakers to a 2 channel amplifier, so why would I want the 4 channel amplifier?
Thanks in advance...

billmerbach

Well I'm using a 200 watt on 6x9 if that helps and I would go for the second one more options less money

MDchanic

10Ω speakers are going to be restrictive to a modern car stereo amp, which is probably made for 4Ω. That means that you won't get the volume or power you'd expect.

Also, OEM speakers are crap, so it'll sound like garbage, too.

If you want to upgrade any sound system, the FIRST thing to do is get a good set of speakers.
You can always add the amp later.

- Eric

Nighthawk

So if I understand correct, the watts don't necessarily need to match from amp to speaker. However, the ohms do need to roughly match. I just read an article which said that ohms decrease if multiple speakers are wired in parallel. How do I know if my speakers are wired in parallel?

Lady72nRob71

If you have factory front speakers, anything more than 5 watts will be too much for them.
Speaker RMS (or continuous) watts need to be higher than or equal to amp RMS watts.
Wiring speakers in series or parallel only pertains to more than one speaker on a channel. If only one speaker is per channel, it does not pertain.
As mentioned, you and safely run a new amp with your 10 ohm speakers but you will not get even get half the power fromt he amp turned into sound. It will work for normal listening but if you want it loud, then you might want to get some 4 ohmers for the new amp and keep the 10 ohmers for if you go back to factory.

You might just want to power the rears until you get the funds to repair the radio, or replace the fronts with more robust ones.
what is wrong with your radio? Have a picture of it?
What size are the front speakers?
I agree with you 100% on keeping the stock look. Aftermarket radios rarely blend with older cars.

Nighthawk

MDchanic,
At this point I'm just trying to get any sound out of the system. I am only adding the amp because I am trying to wire an audio device (such as mp3 player) directly to the speakers. So I'm not trying to add power to the system. Hope that makes sense. With this in mind, what are my best options to get the system to actually work. Also, see my last post, but from what I have read it sounds like speakers wired in parallel have reduced ohms. Does this mean that if I run 2 speakers through each channel on the amp, the ohms will become managable for an amp with a rating of 2-8 ohms?

Nighthawk

Lady72nRob71,
As you suggested, I may end up just powering the rear speakers. How come the front and rear speakers have such different watt ratings? Not sure what's wrong with the radio, but it turned on, lit up, and I could even hear the front speakers engage but no sound. I am not pursuing the fix-it route partially because I would prefer an mp3 or usb jack.
Not sure on the size of the front speakers...

Lady72nRob71

The size of the wire in the speaker's voice coils and sive of the magnet structure determine how much power they will handle. Thicker wire, heavier magnet, more power, louder sound (for the most part). Factory radios only put out about 3-10 watts, so speakers matched to that result in cost savings to the car company. Your 6x9s were bought aftermarket so they made them to handle larger amps i suppose.
For what you are looking to do, buy an inexpensive 25x2 amp and hook up to the rears only. It will make clear sound but no rock concert.

Sounds like the outputs in your original are gone, possibly the result of hooking too many speakers or newer 4 ohmers to it or just driving it into a distorted garbled mess byt turning the volume up too far.
Distortion is the sound of DC being fed into the speakers. With non-vacuum tube amps, this will destroy speakers and amps easily and quickly.

MDchanic

I would love to add more, but it's late, there's a blizzard, and I may have to clear the driveway again in the morning before I can go to work, so I must retire.

I agree with all that Rob says (except for speaker magnet size being related to power handling - that's a separate issue. Power handling derives from the size [cross sectional area] of the voice coil winding, as Rob said, and from how well the physical construction of the cone and its attachments to the frame can withstand repeated rapid acceleration, deflection, and deceleration).

I would just like to say that if you are planning to install a sound system, at what I infer to be your current level of knowledge, I would wait and read some basic electrical theory first. Understanding series and parallel circuits, Ohm's Law, the principles of summing resistances in different types of circuits, techniques for soldering and insulating wire connections, etc., would all help you to do this job well.

We will help you with it, regardless, though.

- Eric

ps: for your needs, have you considered a regular old DIN-sized "head unit" from one of the major manufacturers? I got one two years ago for about $120 that's quite nice, accepts USB, iPod, and eighth-inch headphone plugs, receives digital audio, has a CD drive, and can be operated by an included remote control.

Nighthawk

Thanks, for all the info. I'll start studying MDchanic-I have considered buying a head unit but I like the fact that I can get an amp that does almost the same thing but is smaller and simpler. Is there a real difference between a din head unit and an amp with an audio jack? It seems like they would do exactly the same thing except that the head unit has a fancier interface. So if I'm going to hide the thing anyway, I might as well get the amp which is smaller, cheaper, and has fewer components that might break...

If I bought 4 new speakers, with one of the amps I listed what would you recommend? Any brands or models of speakers which you have experience with?

Nighthawk

Things I'm learning after studying things a little more in depth as MDchanic suggested:
1). Wattage = Power and Ohms = Resistance.
2). Amplifier wattage should roughly match that of the speakers and definately not exceed it. However, it is okay if the amplifier has a lower watt rating than the speakers (they just won't be used to their full potential).
3). Amplifier and speaker Ohms should be matched carefully. And most importantly, "Connecting speakers in parallel is often useful to make a speaker configuration match an amplifier."
I'll probably utilize this fact to use the 10ohm speakers I got from opgi.com. So I will run two speakers on each channel which will lower the total ohms (RR and LF speaker together, RF and LR speaker together)
4). In a Series:
Total Ohms = Sum of Speaker Ohms on Given Channel
Putting speakers in a series can be used to raise total resistance.
5). In Parallel:
Total Ohms = (Speaker 1 x Speaker 2)/(Speaker 1 + Speaker 2)
Putting speakers in a parallel circuit can be used to lower total resistance.

Sorry, I know this is probably all basic information, but I'm mostly posting to organize my research

MDchanic

NOW you're getting somewhere.

Sorry I haven't answered, but I'm at work and have to use my phone to post.

Sounds to me like you're figuring it out, though

I'm not sure, but I'd bet that Crutchfield has a good "basic knowledge" resource, in case you want to look.

- Eric

Nighthawk

Thanks Eric. I have referenced some posts on the Crutchfield forum. One thing I still don't understand is if I can run a 2 speakers in a parallel circuit when they have different ohm ratings. So for instance, could I run my 60watt/10ohm 6x9 speaker with a 3.5" 4 ohm speaker for a total load of roughly 2.86 Ohm's? Or would this result in major volume/power discrepancy between the two speakers?
The reason I ask is that I would like to utilize my 60watt/10ohm speakers if possible and I can't seem to find any small 8-10 ohm speakers with watt ratings over 20. I would like to run each 6x9 speaker in the rear of the car in a parallel circuit with one dash speaker in the front...

69ishHoliday

Yes, you can wire in Parallel speakers that are not the same impedance, and it should work well. A pre-amp of some kind would be nice. I guess you can use your mp3 player headphone output and vary the volume with the source piece, but a real pre-amp would be much better.

Just get a good quality amp rated at a lower power output but look for one with a good signal to noise specification. 25 or 35 watts from a high current, good signal to noise rating will surprise you. - Steven

MDchanic

Good question.

There are two things that will affect the relative volumes of two speakers: current flow and sensitivity.

Current:
In a non-inductive, non-capacitive series circuit with multiple resistances, current flow is the same through all elements (ignoring, of course, the fact that speakers are both inductive and capacitive ), so, in a series circuit, both of the speakers in a channel will be getting the same amount if current.
BUT, in order to REDUCE the resistance of a channel, you will need to connect the speakers in PARALLEL, in which each speaker will see a different driving current, depending on its impedance (which is a measure of resistance, plus other impediments to current flow), but both see the same voltage, so, to predict the relative current flows of each, you would need to use Ohm's Law (V=IR) with a fixed voltage (as you would have in a parallel circuit) to calculate the ratio of current flow between them.

Sensitivity:
Speaker sensitivity is measured in dB per Watt at 1 meter distance, but, in actual fact, it is the current (in Amps) and not the power (in Watts) that determines the strength of an electromagnet
Therefore, the relative sensitivities of the speakers will determine how loud each one is when supplied with the same current. Some speakers are inherently more efficient (and therefore more sensitive) than others, and will be louder with the same input of power (actually of current).

So, if you calculate the relative current flow based on the rated impedance of each speaker, and apply that to the rated sensitivity of each, you can figure out how loud they will sound compared to one another.

Of course, it's easier to just hook them up and see how they sound.

Incidentally, Wikipedia has a good entry on "Loudspeakers."

- Eric

ctsplicer

Have you bothered to check the antenna connection?You say you can hear the front speakers engage but you get no audio.Sounds like a wiring problem with the antenna as well as the rear speakers.

Nighthawk

ctsplicer, no I guess I didn't bother to check the antenna. It was hooked up to the the radio properly but I didn't follow the line farther back. I may test that again, but even if it does work I'm still pretty set on replacing it with something a little more flexible and modern...
MDchanic and 69ishHoliday, thanks for the info, I'll do some more thinking on the subject and post back with more questions
Any specific reason why a pre-amp unit is advisable? Some of the amps I looked at had all the same controls and inputs as a pre-amp unit.

Lady72nRob71

While you can even have good power handling ability with a big voice coil and NO magnet, (or no cone for that matter ) you certainly won't hear very much.
With a undersized weak magnet and good size coil, there will not be enough magnetic repulsion to move the cone far and fast, especially a heavy cone from a large speaker, or a stiff cone from a guitar amp speaker. Also a small magnet give an insight to what size the coil is.

Of course a huge magnet on a speaker does not mean it always handle a lot of power. Kinda like the huge cheap car amps that are mostly empty inside.
There is a point where magnet weight gets into the unnecessarily large catagory, just for looks or for fooling the buyers.

Now seeing a speaker with a tiny magnet almost always means it will not handle much power. A small coil will be inside, with low power ratings.

Hope I cleared things up a little.

69ishHoliday

Regarding Attenuation;

If you wire the rear right speaker and front right speaker in parallel and likewise with the left side you will probably not have an ideal image location as far as front vs rear. If the rear speakers seem to dominate the front you can add a ceramic 8 ohm 10 Watt resister in series with the positive lead of the speaker that is too loud and reduce it's output relative to the other, for that matter you can use a passive volume control if you would like to see how it sounds with three decibel increments of reduction.

RE Speaker Magnets;

There are several different types of magnet and different properties that have much to due with a speaker's power handling. Some makers like MB Quart and Morel make great speakers with solid power handling but don't use massive magnets to accomplish it. Yes, money is well spent on good speakers but if you want to fire up a good amp to what you already own you might be surprised, you can always add a pair of good tweeters on capacitors if you want to extend the bandwidth and move the stage. Pick-up a good old PPI, Fosgate, HK, Linear Power, Soundstream, Zapco etc. There are a bunch of cheaply made off-brand amps out there so I recommend that you stick with a name brand maker and pick-up either a two channel or four channel model for your project. There should be many that meet your needs at around $100 on e-bay.

I'm using an old Zapco amp in my Cutlass and although it is twenty years old it is 110 DB signal to noise ratio and is tough to beat in quality today.

69ishHoliday

This one for example is all you would need and it's new and $99.00

http://www.ebay.com/itm/NEW-SOUNDSTR...item5af3814701

Nighthawk

69ishHoliday, I was planning to arrange the LF and RR speakers in parallel and the RF and LR speakers in parallel because that is the way the original speakers were set up... Is that correct? Your last post mentioned not arranging the circuit so that both left or both right speakers are in parallel...

oldcutlass

I'm going to make a suggestion, as a lot of good points were made in this post. Audio systems performance is based, just like engines on the sum of all the parts working together. I would not just throw in a bunch of mismatched equipment expecting miraculous results.

Lady72nRob71

If you do have the factory speakers in the front, leave them alone if you are adding an amp - they cannot handle any real power.
Just connect up to the rears, enjoy your music and maybe upgrade the fronts later. If you do the latter, and they are small (say 5" or less), add some bass blocking caps in series with them, then connect them parallel to the rears. I did this with mine, since the head unit is from the 80s and it only had two line-outs.
A good cheap way to get decent sound.

Nighthawk

oldcutlass, unsure what you mean by mismatched equipment... I am probably going to end up with equipment from different companies but that does not mean that the equipment is mismatched. In fact, that is exactly what I'm struggling to do: understand how to match speakers and amps.

So far I have narrowed my favorite amps and speakers down to the following (keep in mind that I already have new 6x9 60w/10ohm speakers for the rear.):
Amps-
1. Boss R1002 - RMS: 2 x 50w @ 4 ohms; minimum of 2ohms; 2 channel
2. Lepai LP-269FS

3.5" Dash Speakers:
1. Boss CER 322 - 4ohm; Max 140 watts
2. Planet Audio Anarchy AC32 - RMS: 60watt; 4ohms

So for example if I chose the boss amp and speakers and wired one front speaker with one rear speaker I would have total ohms of 2.86 (40/14). This appears to be in the proper range for the boss amp. Again, this project is on a budget so that's why all the products I listed were under $50... Any thoughts?

Does anyone have any experience with Pyle, Boss, and/or Lepai equipment? Positive or negative?

oldcutlass

If your going to change the head unit and it has a balance and fader control then the 2 amplifier scenario is the way I would go. Most of the newer head units have an aux port for an MP3 or Ipod input. It seems both your amps have a high level and rca low level inputs so that won't be an issue and I would set it up the way you've described in one amp for the fronts and 1 for the rears. I would not combine speaker sets. You can mount the amps to a plate under the front seat. Make sure your power wires go to the battery, is fused, and everything turns off with the key.

69ishHoliday

This is good advice and you would be well served to put an 80 mic capacitor in-line on the positive side of the fronts if they are only 3.5". Doing that I think OEM or aftermarket either one would survive just fine.

A four channel amplifier is in the end the same as having 2 - two channel amps since all the channels act independently of one another. The one that I posted a link to has useable low pass or high pass filters so if you are using two channels for small front speakers you could use the high pass feature and block the low frequency going into them and effectively do the same thing as using a passive capacitor.

69ishHoliday

Pyle speakers are good speakers, probably not as good as several other makers, but better than most. They would be a good dependable choice.

Lady72nRob71

Pyle speakers are good budget speakers. I have a set in Lady (the discontinued 6.5" low depth ones for the rear panels) and they sound quite good and have been reliable

Nighthawk

Great thanks! I think I'm set on the Boss r1002 amp with 2 3.5" 50 watt Pyle speakers.