MG Sports Cars

As Carl stated, speaker ohms need to match the amplifier ohms. If the amp is rated for 4 ohms, you need to use 4 ohm speakers. If the amp is rated for 8 ohms, use 8 ohms speakers. Depending on the amp design, a mismatch can damage the amp.

So, what difference in sound would one notice between a 2ohm & 4ohm system?

Recognizing I'm not an audiophile, I just want to be able to hear the system over the wind & road noise w/top down & at highway speeds, is there a practical difference (beyond cost)?

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So, what difference in sound would one notice between a 2ohm & 4ohm system?

None. The quality will be determined by the overall system. As far as I know, unless you are going for an extremely high end system, any car audio system will be 8 ohms.

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Recognizing I'm not an audiophile, I just want to be able to hear the system over the wind & road noise w/top down & at highway speeds, is there a practical difference (beyond cost)?

The most important factor will be your music selection. You won't be able to enjoy any kind of music that has a lot of dynamic range - you can forget about classical music. If you turn it up loud enough to hear the quiet passages, the loud passages will blow you out of the car. Low enough for the loud passages, and the low passages will be lost in the wind/engine noise. Trying to get quality audio in an open sports car with a V8 (and I'm assuming you have a pleasing exhasut note - ie, rather loud) is an excercise in futility. The wind will overpower most high frequencies.

In my car, if I have the volumn up high enough to enjoy the music over the exhaust and wind noise, it is way over safe listening levels. I'm not sure the exhaust sound itself is not over safe listening levels.

Check out [www.crutchfield.com] for some good car stereo information.

Disclaimer: It's been years since I messed with quality sound systems - maybe things have changed since then.

I think most car audio speakers are 4 ohms these days, Dan. Subs are used in 2 ohm configuration a lot. I believe that the 8 ohm will have greater fidelity, followed by 4 ohm. Like Dan said, in a roadster it won't matter.

I discovered that I can hear the music over the wind noise much better when wearing ear plugs.

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I think most car audio speakers are 4 ohms these days, Dan.

I did some checking, and you're right. Just shows how out of touch with new technology I am.

Most of the music I listen to in the MG is the 1950s rock and roll that I grew up listening to on AM radio - fidelity is of no concern.

It's all about the distortion levels. Ever listen to a top end system where you were in control of the volume when a really kick-ass song came on? You don't even realize how much the volume has been turned up until you start to feel the vibrations in your chest and the neighbors come over? That's clean sound. It is very hard to get that in a car system, especially a convertible. But once you do you'll never forget it. Absolutely the key factor is the speakers. Good speakers will make almost any head unit sound great, bad ones will ruin it. Altec Lansing once made a surface mount 6 x 9 in a cast housing with a paper cone that only handled about 50 watts but what they did with that 50 was nothing short of amazing. Crisp clear sound with dazzling highs that you could still hear with the wind roaring by.

Any amp is going to have distortion specs and the less distortion the better. But amp builders have been playing all sorts of games with their specs pretty much from day one. Look, watts equals volts times amperage, so the entire reason for the 4 and then 2 ohm speakers was to get the amperage up. 14 volts into 2 ohms gives 7 amps. 7 times 14 equals 98 so the absolute most you are EVER going to get out of a car stereo is 100 watts per channel and that's into a 2 ohm load with ZERO internal resistance in the amp. And since amps typically rely on impedence matching that means the amp has the same impedence or resistance as the load, or an overall system impedence of 4 ohms, so you just cut that in half.

If you are looking at amp specs and they are claiming more than 50 watts per channel THEY ARE LYING!!! If they are lying about the power specs, what does that say about the distortion specs? MORE LIES!!! And it makes a difference how they quote it, including the distortion threshold and the test set up.

The ONLY way to exceed 50 watts is to reduce the impedence even further or to increase the supply voltage. NOTHING else works. So find an amp builder who posts realistic power specs and you might have one who posts real distortion specs too, but it's still a good idea to read the reviews, especially lab testing reports.

Finally, "Garbage in = Garbage out" so pay attention to the connections and the source. It is possible to have a good sound system, but nobody said it would be easy or cheap. Oh, and the stuff has a finite life too so plan on replacement costs.

Jim

Well Rob and Dan, I guess that between Carl and Jim, Dr. Bose don't stand a chance :-) (LOL)

Ha! I don't think anyone will be mistaking me for a Phd. Engineer from M.I.T.

Since you mentioned him, a quote from Amar Bose:

There are two reasons we cut out the specifications:
1) We don’t know of any measurements that actually determine anything about a product, and 2) Measurements are phony, in general, as they are printed.

Yep for real; you and Bose somehow have connected DNA (LOL)...... Sound systems are one bad addiction on the pocketbook and at my age, my hearing can't even pick up the all of the frequency range :-)

Here's a statement from the spec sheet of an Alpine 500W @ 2ohms amplifier:

"Power Supply: The MRP-M500 amplifier's power supply uses MOSFETs to convert DC battery voltage to the higher DC voltages needed for high power."

As I said earlier, my knowledge of this kind of stuff is well past the "use by" date. I remember the old tube type radios used up until the mid 60s, where they stepped the DC voltage up to 300 volts using a vibrator and a transformer. I don't know what they use get the higher voltage today (well, I "kinda" know, but not in detail).

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Sound systems are one bad addiction on the pocketbook...

That's why I gave up on them years ago. I'm living with a 20 year old system in the house, and that replaced a 20 year old vacuum tube setup. When I bought the sound system for my MGB a few years ago, it was an 8 ohm system. Being an old fossil sucks.

Dan, as we get older we need higher Ohms :-)

Ok so what is a good system without the Rap music and astronomical base. You know normal people Dan.

I like what Carl mentioned - I've ridden in the '72 MGB with full exhaust and also with open downpipes. Also mine('79 294CI) with exhaust(no mufflers) - you can definitely hear the stereo but quality is an issue. I attributed this to wind noise in the cabin and exhaust. However a friend of mine recently picked up a FB RX7 and with his moderately loud exhaust he has the same issue. The only solution I've found is to use headphones which is a lot cheaper ;) - however I only use them when on the highway - otherwise no music so I can be more aware of those around me and any emergency vehicles that may be nearby. The plus is that a good set of headphones will always beat an amazing stereo system.

Note - I'm sure with a top up/GT and enough sound insulation you can get a great sound quality - its choice is yours and thats what makes modifying these cars so much fun.

MGBV8 Wrote:
-------------------------------------------------------
> I think most car audio speakers are 4 ohms these
> days, Dan. Subs are used in 2 ohm configuration a
> lot. I believe that the 8 ohm will have greater
> fidelity, followed by 4 ohm. Like Dan said, in a
> roadster it won't matter.
>
> I discovered that I can hear the music over the
> wind noise much better when wearing ear plugs.

I tend to listen to my music at levels that are "probably" beyond a safe listening level typically. :) Great sound can be had in an open top car, including MGB's. The key ingredients are 1. Make the car as quiet as possible. It takes a ten fold increase in power to double the loudness of the sound you hear. It's often times more cost effective to lower the overall noise level of the car by 3db or so using Dynamat or something similar, which is the same effect as doubling your amplifier power. (yes it adds weight to the car. For me, who cares) 2.Choose the best possible gear. I've always preffered using 6 1/2 seperates (seperate woofer, crossover, tweeter) mated with a pair of small subs, 10" being my favorite. I never use the amp built into the head units as they just can't compete with a good outboard one. 3. Install the gear properly. Make sure your amps have good airflow and power cables to supply current. Use a capacitor of 1 farad or bigger on the power line suppying your amps. (charges and gives off voltage very quickly to "pad" peaks in your amps output, helping to keep the headlights from dimming while you rock out to deep bass notes) Higher frequencies from your car speakers travel in a more linear fashion than do the low notes, so the closer you can get your mids/ tweeters to ear level, the better they sound and clearer / louder you will hear them. Use efficient speakers and amplifiers. Many speakers will play at 90 db or louder with a 1 watt input. Reserve amplifier power (as much as you can afford to some degree) is what gives the sound clarity and punch at really high volume levels, even though in actuality you are only pushing a few watts at most. For me, I listen to mostly rock and roll of all types and I've always preffered the sound of sealed boxes over ported for what I listen to. Sealed boxes increase your speakers power handling, control woofer movement, and can hit the deepest of bass notes (although not as loudly as a similar ported design. A port is tuned to a set frequency, and no bass notes below that frequency can be produced because of cancellation. I know ported designs can sound great, but for average people, sealed boxes are easier to build and they sound great. Besides, on certain music port noise is often a side effect that has to be dealt with. Again, I like smaller subs with a proper internal volume box with an electronic crossover set to cutoff around 80 hz )

I have the Moss power window kit in two B's and work great. One suggestion. Install the SW's any place but the door, any rain gets in there will do funny things. Not a problem in the GT but a problem in the RD.

About sound, my RD has a nice stereo with speakers in the Miata seats (really good speakers) but I rarely listen to it.
I like to listen to the blower wind and the engine.

The GT is getting the hidden stereo, no dash stereo. Speakers will also be hidden in the doors same with the rear speakers.
Also hidden antenna.
About sound, I have done some research on sound. It appears that the prefer location for speakers is the floor due to the sound goes up. The floor is not a good location for various reasons.
The GT that I sold, I build boxes that fit under the seats and an angle and place the speakers in the boxes. Did it worked, YES, sound was great. The problem is to keep the dust away from the speakers.
How many Watts etc etc... I have no idea about the tech stuff, I just buy the matching pieces and installed.

So far I'm still strong enough to roll up my own windows. It is an MG after all . . . :-)

Cheers,
NCtim

Is it just me, or do lots of you have trouble getting the windows to roll up and down like they first did?

On a new MGB rolling the windows up or down was no big deal. You could reach across the car and wind the passenger's window up or down with two fingers. And if they still worked that easily there would be little need for power but it seems that a bunch of things have conspired to take that away from us. Maybe it would help to have tips and tricks to get smooth running windows. For instance, I've heard that one of the screws that hold the regulator to the door can only be so long and no more, as it will cause binding and stiffness. (I have yet to check this on my car but would almost guarantee it is a problem there). Anyone else?

Jim

Jim, I"ve found that a good cure for a sticky window or one that is hard to raise or lower in a shot of silicone lubricant in the felt glass channels. Works like magic to make the window smooth and almost effortless. You'd be surprised how much drag that felt can cause on the glass. And being silicone it weathers well and doesn't seem to wash away in the rain or car washes.

Jim,

I know it was easier when I was younger, but I can hardly bend over comfortably enough to put my socks on in the morning (and I'm not a large guy). I think our age hinders things these days. I can't imagine doing some of the stuff now my wife and I used to do-LOL! That said:

In my last MGB ('72) I had a Harmon/Kardon receiver and small 100? watt amp that ran home-made Altec Lansing speakers made from some studio monitors I had lying around. Driving from Chicago to Asheville with the top down this worked as well as any off-the-shelf system and better than anything under 45 mph.

In those days we didn't have subwoofers, we made our own. I used a 2 ohm 12" woofer and fed both channel's power feeds to both connectors (right channel to +, left channel to -). You had some low volume hum but at higher volume the sound and base was fantastic. That's basically all a sub woofer is anyhow, now they just put some kind of filters or resistors in them to get rid of the hum and charge you $200 to do it.

I glued (hey, I was 19-years-old) the tweeters to the dash and put the mids in the doors and behind the seats with the cross-overs. Sounded great, looked like a college kid's car, that's all I needed to crank Pink Floyd and REO Speedwagon to appropriate listening levels.

As Roverman says, "Onward!"

NCtim

then there was the Craig Power Play 8 track mounted between the rollbar on the deck in my TR6.....and fly'n low and fast

I wish I could find anything as crisp, clear, and efficient as the old paper 6 x 9 altec lansings in cast frames that I used to have. Wouldn't handle extreme power, only about a 1" voice coil, but man, they were precise. Knowing what I do now, I'd have kept them forever and had them re-coned when I could.

Jim