1986 Toyota MR2 - We’ve got a damn great hump...

[Sweetpea]

Nov 2, 2024 21:44:00 GMT mk2cossie said:

check out hexibase on YouTube.

Oh, what did you do that for!? I have enough trouble watching junk on PooTube without people suggesting more of it. Oh well, another rabbit hole to fall down. 


Mark,

You should get a 'reasonable' bass out of the 6 inch speaker. I don't know but I suspect that is what's in the Lexus and it sounds 'fine'.
I guess the question here is what do you want? In what way do you feel the current set up is deficient?

Like mk2cossie says, you may be able to get what you want by getting a decent amp (if you don't already) and an EQ so you can set it up.
If you want that thump of a kick drum then, personally, I'd suggest go big and hide it. You are more likely to have success that way than trying to do something clever with small stuff.
That said, I put a silly speaker in a tiny bit of wood and it seems to work. I don't understand how. I think it's got so much power available that it just grabs common sense by the neck and headbutts it into submission.

A couple of things to bear in mind.
Those tiny speakers in your TV probably have a very well designed cabinet behind them to get the best out of them. You won't be doing that unless you are very clever indeed.
Secondly your living room is a quiet well damped place. A car isn't and your car definitely isn't. If you put your TV in your car you'd probably find it struggled.
To make matters worse you have to overcome the natural bass noise of the car. Any bass set up that sounds natural in a moving car normally sounds over emphasised with the engine off.

And lastly, what do you listen to?
Katy Perry or Dua Lipa have truck loads of really low bass that really wake the MR2 up. But play some Genesis from the late 70's or early 80's and there is none. And they are a prog rock band for goodness sake. You may be looking for something that isn't there in the first place.
Why is there no bass in older recordings? The way it was explained it me was that if you tried to have lots of bass it would just cause the disc cutter to skip into the next grove when trying to cut the master record. So music was mixed with that in mind. It was one of the purposes of the RIAA curve used on vinyl. It took all the bass out of the recording so they could get the tracks closer together. Or so I believe.
Once you move to digital recording and reproduction none of that matters and you can have as much bass as you want so tastes have changed over the last couple of decades.

And lastly, lastly... If you tweak your hifi's eq you can make one record sound great, but another will sound curse word. (especially if you have 7 or 9 bands to play with.) So you tweak again and keep going iteratively. Eventually you'll find settings where most things sound lovely. If you can't get to that point then something is probably wrong. Listen to the human voice on it too. You are very used to listening to people speaking and it'll stick out like a sore thumb if somethings wrong in the mid ranges. Beware though because a lot of radio stations process their mics horribly and there is no chance on Gods green earth that they will ever sound natural.
I have to admit that when I do the iterative fiddling process in the MR2 I'm not finding a totally sweet spot. This would suggest that the bass reproduction has some horrible peaks and troughs in the frequency response. Frankly, given what I did, that's no surprise. I'm more astonished that it works as well as it seems to.

James

[blackpopracing]

James, thanks for the detailed response.

I'm not sure if I really need more bass - just the topic got me thinking..

The real issue in my car is the engine is too noisy for the stereo to work well. It would have decent bass if the rear side panel speaker were fitted in the boot panel instead, but if I could actually hear it then it would be a major improvement

Musical tastes - everything from Abba to ZZ Top. Opera, Kate bush, Floyd, Genesis, classical and trance euphoria - I have an eclectic taste in music

[The Cat Herder]

Nov 4, 2024 13:35:46 GMT blackpopracing said:

Musical tastes - everything from Abba to ZZ Top. Opera, Kate bush, Floyd, Genesis, classical and trance euphoria - I have an eclectic taste in music

Not trying to thread hijack here, but looks like you’ve been poking around my record collection. 👍

[jimi]

^^^^^^
With a few additions it could be mine as well

[Sweetpea]

Nov 4, 2024 13:35:46 GMT blackpopracing said:

I have an eclectic taste in music

I approve of people with varied musical tastes.
I always used to say that I had a varied musical taste but I had to draw the line at jazz which I just couldn't stand.
Of course I've come to realise that I quite like some jazz and that a lot of the pop music I enjoy has a strong jazz influence.

So there we go, wrong again. It's a good job I don't mind being wrong. Especially when you learn or discover something new.

James

[Sweetpea]

Just to prove the point that I don't like jazz except when I do, this is sublime in my opinion...



Luckily, other opinions exist and you are all entitled to disagree. (Even though I'm right! )

[skinnylew]

Nov 4, 2024 13:35:46 GMT blackpopracing said:

James, thanks for the detailed response

Musical tastes - everything from Abba to ZZ Top. Opera, Kate bush, Floyd, Genesis, classical and trance euphoria - I have an eclectic taste in music

This made me smile so much. Someone who has similar music spectrums is a rare thing indeed. My 6 disc changers tended to have a Genesis/Phil Collins album, a Yes or ELP album, 2 trance nation discs, a Delirious album, and a Jungle or D&B disc. Radio stations similarly eclectic, depending on mood and journey 😂

[75swb]

Nov 6, 2024 18:16:00 GMT Sweetpea said:

I approve of people with varied musical tastes.I always used to say that I had a varied musical taste but I had to draw the line at jazz which I just couldn't stand.
Of course I've come to realise that I quite like some jazz and that a lot of the pop music I enjoy has a strong jazz influence.

So there we go, wrong again. It's a good job I don't mind being wrong. Especially when you learn or discover something new.

James

I still do draw the line at jazz.  Now, swing, blues, big band, I will happily listen to, but I just can't get into Jazz. I actually went to a jazz festival this year which was excellent for largely playing no Jazz at all

[Alpina99]

Nov 6, 2024 18:16:00 GMT Sweetpea said:

Nov 4, 2024 13:35:46 GMT blackpopracing said:

I have an eclectic taste in music

I approve of people with varied musical tastes.
I always used to say that I had a varied musical taste but I had to draw the line at jazz which I just couldn't stand.
Of course I've come to realise that I quite like some jazz and that a lot of the pop music I enjoy has a strong jazz influence.

So there we go, wrong again. It's a good job I don't mind being wrong. Especially when you learn or discover something new.

James

Totally agree,
I too have eclectic music tastes,
I've always said I like everything from Bach to Black Sabbath, ( although no lover of Country or Rap, as in curse word !!)
Nigel

[Sweetpea]

Ah, a group of blokes brought together by a love of cars and eclectic music. Makes a chap feel like he belongs. I might have to buy a pipe and a pair of slippers...

Or probably not.

Nov 7, 2024 3:15:32 GMT 75swb said:

I actually went to a jazz festival this year which was excellent for largely playing no Jazz at all

Funnily enough I believe Jazz FM got in bother with Ofcom for much the same reason and ultimately rebranded as Smooth FM.

[Sweetpea]

I’ve spent more time fiddling with the sub woofer. Adjusting it and readjusting it. This is bad news because it suggests something is wrong with my frequency response. Now that’s not any sort of news. Stick a large speaker in a small wooden board paired with front speakers that are too small, put them in a tiny car and you are never likely to achieve studio quality sound.

I’ve heard a load of sub woofers over the years. By and large they sound somewhere between terrible and really horrific. Done properly you can’t tell that you have a sub at all. But then you’ve spent a load of money on something you don’t notice so a lot of people turn the up too much so you know you have one. The other ‘problem’ with subs is that you shouldn’t be able to hear where they are in the room (or car in this case). But that only works if the crossover is set to a pretty low frequency. Set it too high and your ears can locate where it is.

My dash speakers won’t go low enough so I have to have the crossover set a bit higher meaning I can hear where it is. I can set it to so it blends in really nicely but then you don’t get the sub bass that I want to hear so I’ve got it a little loud too. The Vibe amp has a ‘Bass Boost’ control. It’s an EQ centred at 45 Hz. Adds a pit of punch. I had a chunk of that dialled in but I’ve backed it off a little so the sub blends in a little better.

Yeah… I can’t quite get it right, but, I’m being hyper critical and it’s pretty bloody good for what it is.
If you sit in the passenger seat and listen to it things are actually better. You don’t feel it so much but there is more distance for it to merge into the car and so it’s harder to hear where it is. I might do a rebuild and move it to the other side of the car one day. But first I want to listen to it while on the road and that means actually having a car that’s legal. Like having an actual MOT and stuff.

Anyway, during this extensive testing I did notice this…





It might not be immediately obvious but the centre bulb in the dash illumination has gone out.
Well that’s of no consequence so we’ll just pretend we didn’t see it. Right?

We didn’t see it… Right?

We didn’t…

Ah poo. I can’t unsee it and it’s going to annoy me even though I can’t actually drive the car anywhere. Let alone drive at night.





I’d forgotten how many screws you have to take out to get this apart. And to make life marginally harder the light switch is on the binnacle on the MR2 so when you’ve taken it all apart you can’t turn the lights on to test it. Well, I mean I did, but it’s awkward.

The bulb was fine.





So I just reseated it and retensioned the contacts and it’s fine.
Yes, I did try thumping the top of the dash before I took it all apart.

Anyway that’s all fixed now.
What, you want proof? Really!? Ok. Here you go.





See! Would I tell you porkies?

In the next episode we’ll either get back to filling those holes in the bumper (remember that?) or we might modify the pop up headlights to make them less irritating.
“But, James, why are they irritating?”

I do like a leading statement to arouse interest.

James

[skinnylew]

I always considered a sub there to make it's presence felt and heard, if it ain't vibrating the mirrors it ain't loud enough mind you I always went with Alpine speakers because the quality was always better, had 10" type E subs but the only one I have left now is a 12" Type R beast sat in the loft for 10 years plus 😑

[teaboy]

I don't understand any of this crossover sub frequency stuff at all.

I particularly wondered why they are called woofers, do they have something to do with dogs?

[Sweetpea]

Nov 10, 2024 22:54:13 GMT teaboy said:

I don't understand any of this crossover sub frequency stuff at all.

When I get a moment I'll write something that will try and explain. The theory isn't hard. Actually designing a set of audiophile speakers probably is.

Nov 10, 2024 22:54:13 GMT teaboy said:

I particularly wondered why they are called woofers, do they have something to do with dogs?

You know that's a question I'd never even thought to ask and don't know the answer to. But according to Wiki...

"The name is from the onomatopoeic English word for a dog's deep bark, "woof"[1] (in contrast to a tweeter, the name used for loudspeakers designed to reproduce high-frequency sounds, deriving from the shrill calls of birds, "tweets")"

It seems you are an audio expert Mr T!

[Sweetpea]

OMG





We might come back and chat about this one day after I write some stuff about crossovers. I've got to admit I find it a bit, er, disquieting. ...If that's the right word... Or even any sort of word.
(Yes I know that's the number of views not the number of people reading but it's still a ridiculous number.)

Anyway, thank you all for reading. It's lovely to have you all along for the adventure. 

James

[mk2cossie]

Happy to be part of a number

[Sweetpea]

Nov 10, 2024 21:39:57 GMT Sweetpea said:

Would I tell you porkies?

In the next episode we’ll either get back to filling those holes in the bumper (remember that?) or we might modify the pop up headlights to make them less irritating.

Apparently I would tell you porkies ‘cos we are talking about crossovers.

We’ll keep this simple. No sums. Almost no numbers. Just a couple of drawings. Just a very basic look at what they do and why we want them. If you want to go deeper we can.


The lowest frequency you can hear is about 20Hz. The highest is about 20,000Hz. For decent hifi we want the response to be flat between those end points. So for a particular power across the frequency range we want the same volume out of our speakers.
There is a lot wrong with those statements. For a start, at the low end there comes a point where it’s too low to hear it but you can still be aware of it. You start to feel it. If you’ve never done it go to a cathedral and listen to somebody playing a big pipe organ. The sound is unbelievable. The biggest pipes can get down to a few Hz.
If my assumptions of my audience demographic are correct, none of you can hear 20kHz. About the only people who can are youngsters and they probably aren’t reading this ‘cos they are mucking about on X or something. Your hearing’s high frequency sensitivity drops off as you get older.

Even when you could hear to 20kHz most of you would have had a notch at 15625Hz. That was the line frequency of an old tube TV. I’m not sure if we actually went deaf at that frequency or if our brains just filtered it out. Young people that have only watched flat screen TV’s don’t have that 15625 notch and they go nuts if they walk into a room with a tube TV in it. They can hear a loud whistle but they can’t work out where its coming from. It’s really funny. (He says speaking as an old person.)

No loudspeaker driver can do the whole 20Hz - 20kHz range. You need a little one to do the high frequency stuff, a middle sized one to do the mid frequencies, and a big one to do the bass.
That said, a reasonable sized, say 4 to 6 inch mid in a well designed box will get pretty low. Bigger the better. But you aren’t going to get really low bass.

Ok, so let’s put a couple of drivers in a box, a little tweeter and a bigger mid, and see what the frequency responses do. Later we might add my sub to the drawing and see what my problems are.





We can see the mid driver can get a fair way up the frequency range. And the tweeter gets a fair way down. So there is a range of frequencies where both are working. What does that do to the overall frequency response? Well we get more volume out of it where both drivers are active and add together.





Oh dear. We’ve got a damn great hump in what we hoped would be a flat response. That won’t do.
What we ideally need to do is design the drivers differently so the mid doesn’t get quite so high and the tweeter doesn’t get so low. Just nicely so that they bump into each other. Well that’s not going to happen and there is an easier way of dealing with the problem.
We should put the signal going to the tweeter through a little electronic circuit called a high pass filter that knocks off some the lower end of its frequency range. And put the signal going to the mid through a low pass filter that knocks off a bit off the top of its frequency range.





Now the two drivers bump nicely into each other. The overall frequency response is now flat.





Let’s call these two filters a crossover. That’s it, we are done.
There is another reason why we need to filter the low frequencies off the tweeter. The tweeter is a small delicate little thing. Stick a few hundred watts of bass up it and the winding inside it (called the voice coil) will melt really quickly.

There are two ways of doing crossovers. Almost all are built into the speaker cabinet and are called Passive Crossovers.





The audio power amp outputs the full range of frequencies to the speaker. Then the filters in the speaker split it up into the ranges need by each driver.
This works well. I’m listening to some passive crossovers in my speakers as I type this and they are great. They do lose a bit of level from the system though but that’s rarely a problem.

The other way is what we do in professional audio. Or really high end home hifi. Or anywhere we need loads of control so car hifi is a good example.
We can have an active crossover first. Active because it’s a powered circuit. This splits the audio band into ranges which then feed a power amp for each driver.





Power amps aren’t cheap so this is an expensive way to do it. But it has the advantage that it’s more accurate in the frequency split part and it’s more easily adjustable. In a proper recording / mixing studio you can tune the speakers to the room they are fitted in if you want to.
In the stuff I work with the active crossover and power amps are built into the speaker cabinet. You just plug it into the mains, feed it sound, and enjoy your wonderful tunes.

So that’s part one of the story. Happy so far?

James

[teaboy]

What is the difference between a speaker and a driver?

[Sweetpea]

Nov 14, 2024 21:58:28 GMT teaboy said:

What is the difference between a speaker and a driver?

Ah... You know I was trying really hard to keep my terminology clear but I know I'll have screwed it up somewhere. It's complicated because in real life we use 'speaker' to mean different things.
I was trying to use this terminology...

What I'm trying to call a driver is this -





That's a mid / bass. A tweeter is -





The problem is that those things above are also called speakers.



When I'm writing 'speaker' I mean some drivers in a cabinet.





Or these if you want something better -







To complicate matters in my industry a 'speaker' also includes the amplifier that drives it.
We use a lot of these things.





That thing in the back is the active crossover and power amps that run the drivers in the front.
Undoubtedly I'll have mixed my terminology somewhere in that post. And I'll continue to mix my terminology. Sorry.

James

[Sweetpea]

Just to complete the stealing of photos off the internet this is a passive crossover.





And this (apparently) is an active crossover.





The passive one (that's normally hidden inside your speaker cabinet) is a very recognisable thing. They all look something like this. Nearly.

The active one could be any old electronic circuit. You'd need to be reasonably good at electronics to realise exactly what it was without a circuit diagram.

I said that nearly all passive crossovers look something like the top photo. Well somebody is going to open their speakers and tell me that they have only one capacitor going to the tweeter. Technically that's a high pass filter and it's there to stop the bass power cooking the tweeter voice coil. But it's not really a crossover. They were being cheap and just couldn't be bothered.

It's actually a really common practice on coaxial car speakers.





You can see the filter capacitor (the yellow thing) hanging off the back of the connection strip.