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MG MGF Technical - door tweaters

i.ve just bought some tweeters as the mk 1 does not have them,and as i up graded to mk 2 door cards i thougt i,d get some.says on the box,includes all wiring which is about six inch long. it says to add anon polarized electrolytic capacitor,and a volt resister,not inc . what are these has any one fitted any ,and to be honest,what do tweeters actually do to improve the sound. dont know why i got them really, oh yea i do they were as cheap as chips, thanks all ........mel.....
m e johnson

Mel,

Normal speakers work hard at producing the complete frequency range of the sound required, find it difficult to cope with the extreme high and low ends, hence tweeters (high) and woofers or subs (low)

Tweeters emit the high frequency element of the output from your head unit, adding clarity to the sound. To do this, a filter circuit needs to be introduced to the wiring to the tweeters to only allow the high frequencies to reach the units. This is where the capacitor and resistor come in.

However, you can't just through in any old components, so I suggest you buy a pair of "cross-over" units from a car audio dealer. They will also provide you with wiring details.

If the existing door speakers are 8 ohms, and the cross-over circuitry is also 8 ohms, then connecting them in parallel will result in 4 ohms overall - which should be OK. Anything lower than this, and you risk blowing up the entire system!

Good luck.

Sam


Sam Murray

Basicly low freq's cause the speaker cone to move in and out slowly, high freq's quickly. Low freq's have to shift a lot of air to be heard, high freq's need not.
For this reason there is no 'good' solution, either you go small for high freq's or big for good bass.
Almost all speakers bigger that 7cm have a 'solution' to this problem, the 'cheap' solution is called dual cone, where there are two speaker cones on the same magnet, one small and one large, but the movement of the 'bass' cone causes distortion. The more expensive version has two (or more) seperate speakers in the same housing (one tweeter, one bass and an option midrange).

The second problem is that of directionality, the higher the frequency the more directional it is, so with bass you can hear the sound where ever you are in a room or car, just the volume changes, with high pitched noise the sound is much more directional, so falls off very rapidly as you go 'of axis'. The story used to be that you point the tweeter on the drivers door at the passanger and visa versa, so the fact that you are off axis to the nearest speaker helps balance the volume of the fact that the other speaker is five times as far away, but this falls down when your body gets in the way (your legs in this case).
Moving the tweater away from the main speaker alows you to place it in a position where there is a line of sight from your head to the tweeter and so will give you better top end.


The "cross over" mentioned usually has a filter circuit which cuts the top end out of the signal going to the bass and the bass from the signal to the tweeter, that will remove any high freq comming from the original speakers. What is sold as a cheap 'cross over' is simply a resistor and a capacitor, and not really a crossover at all but a 'high pass filter'
Will Munns

I liked my explanation much better. (only joking).

Well done Will!

Sam
Sam Murray

Hi Folks,

I used to involved in speaker design and have been considering an upgrade to my MK1 F’s speakers.

One thing we have in our favour is the size and width of the doors, which effectively act as speaker enclosures.

The route I am considering is to run the front speaker channels into a crossover, replacing the existing door speakers with dedicated woofers (has anyone done this?) and then sourcing a suitable tweeter system.

This should result in a great improvement, particularly to bass response and should negate the need for a subwoofer.

What are the MK2 tweeters like? I imagine they are a small piezo unit with a capacitor to filter the low range. I’m generally not keen on this arrangement; can anyone comment on if they’re worth using and if it’s viable to source MK2 door panels to fit them in?

Cheers, Russ.
Russ Mellor

> which effectively act as speaker enclosures.

But unfortunatly are made of bits which resonate :-(

>replacing the existing door speakers with dedicated woofers (has anyone done this?)

I beleive that Sony sell 'compolent' speakers which are only the bass driver, not having a co-axial tweeter will reduce the space requirements in front of the speaker and work in your favor for choice.
If you only want to remove the top end from the main speakers you could do it just by snipping the wire to the tweeter.

>I imagine they are a small piezo unit with a capacitor to filter the low range.
Yep, cheap simple and fit for purpose

>I’m generally not keen on this arrangement
it's a classic high pass filter, not sure what else you want (or think a crossover will give you for the top end).
Will Munns

thanks all, it is a bit over my head this i think it will end up as a can,t do job i just thought it was a easy wire in thing,tweeters destined for the loft,ebay,or probably wheelie bin...........cheers .........mel, and his no go upgrades.!!!!!!!!!!
m e johnson

Hi Will,
>I’m generally not keen on this arrangement
it's a classic high pass filter, not sure what else you want (or think a crossover will give you for the top end).

I’m not keen on the use of the piezo tweeters (certainly in a hi-fi or PA application), I’ve previously found them to be cheap and harsh, whether this would be appreciated in moving F is another thing, so I’m interested to hear that you think they’re fit for purpose. There can be no issue with use of capacitors whether in a crossover or not, you misunderstood me.

It’s true the doors will resonate but given the space limitations in the F, I consider that using a dedicated woofer such as the following Mike Satur door speakers http://www.british-cars.org.uk/kimber/satur/iceaudio.html would improve bass response. As would using a crossover with an inductor to filter high frequencies.

I prefer the idea of a separate tweeter that can be placed higher on the door panel for the reasons you specified in your thread.

I imagine there’s been much thread traffic regarding speakers for the MK1, has any testing been done and is there a consensus of opinion on the best way to go.

Cheers, Russ.


Russ Mellor

I fitted Mike Satur tweeters to the doors of our *F* - work very well, give that extra little bit of sharpnes that I require AND as usual they came from Mike with full instructions and all that was required.

All in all I seem to remember that it took about 90 minutes per door to do.

And as BTW these were an origanal Rover fit to another car and complete with new door pulls into which they are fitted - don't know if Mike still does these as I did do this job some eight years back.

Ted
Ted Newman

>I’m not keen on the use of the piezo tweeters
>(certainly in a hi-fi or PA application), I’ve
>previously found them to be cheap and harsh,
...
>so I’m interested to hear that you think they’re
>fit for purpose.

Sorry I was talking about the using a cap as a filter. The only true way to get a real good noise using the available holes and speakers is to use some kind of active filter arangement (it's amazing what BOSE can acheive using a simmiler arrangement!)

>whether this would be appreciated in moving F is
>another thing
This is my 'fit for purpose' comment.


.......................................................

>it is a bit over my head this i think it will end
>up as a can,t do job i just thought it was a easy
>wire in thing,tweeters destined for the loft,ebay,
>or probably wheelie bin

Don't be disheartened by the 'chat', the tweeters are easy to wire in, adding a cap in line they should simply slap into circuit across the standard speaker in the door. You can spend a lot of cash getting professional audio in a car, but if you just want to hear the damn thing it is much easier!
Will Munns

THANKS will ,what do you mean by adding a cap in line ?
m e johnson

This thread was discussed between 19/01/2005 and 22/01/2005

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