Maplins close-out on AP100Z0

[5th element]

My dad once phoned up asking if they had in stock a particular toroid traffo, toroidal she said?? is that some make.....

[Matttcattt]

Originally posted by SimontY
Hi Matt,

What you really want to see is the frequency response graph, and the impedance might be useful too I reckon - the same might be nice, to help keep it all simple.

You really want the tweeter to play smoothly down to 2khz or below, and hopefully to have a resonance of much lower than that, but if not, never mind. Don't worry about the sensitivity.

Power handling also doesnt matter, as long as you x-over at 2nd order or steeper. 70w isn't going near the tweeter - that will only get used for the bass in reality - unless you actually try to break the tweeter

I'd go for an Audax tweeter I reckon, as being the same brand and relative price point, it might match really well.

The spec sheets of the AP100Z0 and TM025F1:



The impedance is 8 ohms...

By the look of the graph, it should be flat to about 1.5kHz.

Thanks for the advice, but i'll wait for a second opinion...

[richie00boy]

I like them If bigparsnip cannot find out in the next couple of days if we can still get these, I can get my mate that works in the Sheffield city centre one to find out.

[bigparsnip]

I only work there part time, so unless I go in tomorrow (it is only a five minute walk from where I live so it isn't too much trouble) it may take a while ofr me to find out, so you may want to get your friend to see if he can check too.

[SimontY]

Originally posted by richie00boy
my mate that works in the Sheffield city centre one

Cool, that's my local Maplins nowadays

What's your mate's name and what does he look like? If you don't mind, curiosity...

[D1GGY]

5th Element:-

Are you able to define why you prefer a sealed enclosure over a ported one for me? in your reply, unless i have read it incorrectly ( a definite posibility) you only state a preference and not the reason why you like that preference.

Please humor me and explain further, I am asuming that a ported enclosure would sound slow and undefined with no punch???

I am also a little confused by some items in your explanation:-
M[I]I think the bass loss in a sealed will be negligable or even apparent because it actually plays louder lower. [/]

you then go on to say:-

I am a big fan of sealed boxes anyway better bass quality. Usually for a small pair of speakers I would want to go ported to maximise bass output but in this case sealed, to me, would be fine.

Is Louder lower different to maximum bass output?

with a ported design is the bass output, centered around the tuned frequency of the port?

Would anyone be able to summaridise the different charactaristics of each design, the pro's and con's?

am i close or heading off on one?

still gives me something to think about over lunch

m

[baggystevo82]

Hmmm, this is my understanding of it from reading threads like this and just thinking about it (though that could change soon as ive just ordered 4 of those 4" drivers too, hehe)

With a ported enclosure, the spl you get direct from the driver isn't far off what you get in a sealed enclosure, and goes down to a similar level too (around 100Hz in this case). However, if you add to this the spl from the port (assuming it is tuned correctly), this adds itself to the original spl from the driver itself. As you can tune the ports, this enables you to extend the bass response, but as the air has had to travel a different route to your ear than the air coming direct from the driver cone, there will be phase errors, which would reduce the definition and clarity of the bass, even though it would be louder. However, with a sealed enclosure, there is only one source for the sound to come from (assuming enclosure colouration is negligable, and that we ignore room reflections ), the driver cone itself, meaning that all sound is in phase (that originates from the speaker) resulting in tighter cleaner bass, but with not such a flat total spl response lower down.

The best solution I can come up with is to have two bass drives, one sealed and one ported. the sealed one going down to 100Hz, and the ported one only doing 100Hz and below, so it doesn't mess up the sound where the sealed enclosure can cope perfectly well.

PS Im not pretending any of this is fact! hehe, just my understanding at this point

Steve

[SimontY]

"Are you able to define why you prefer a sealed enclosure over a ported one for me?"
His reason is probably that sealed gives less clue that you're hearing something that is artificial and not live. All ported speakers seem to laag when moving from one bass note to the next, causing a smearing of the bassline, a confusing mush. How bad this is depends on many factors. Particularly dependant on the music played - something fast and intricate with plenty of presence in the bass is tough.

"Please humor me and explain further, I am asuming that a ported enclosure would sound slow and undefined with no punch???"
Can sound slow and undefined, but defined is misleading - I believe the leading edge of the note comes out well through ported speakers, but that real bass doesn't always have a sharp leading edge. Ported bass is punchy, sealed is not, by the way most people describe 'punchy'. PA speakers in a club are a good example of all the pros and cons of ported speakers IMO. Of course, they're not always ported

"I am also a little confused by some items in your explanation:-
I think the bass loss in a sealed will be negligable or even apparent because it actually plays louder lower."
The rolloff starts sooner in a sealed speaker, but is more gradual - 12db/octave rather than 18db/octave (I may have the numbers wrong) so when you get really low - the ported has no useful output but the sealed has some. Sealed bass would surely be no use in an anechoic room ie. no reinforcement from the room, but its rolloff may work better than ported in a real situation/room.

"Is Louder lower different to maximum bass output?"
Yeh generally, because most ported designs emphasise bass at the tuning frequency to make a slamming, thumping sound. And I believe it is group delay that makes this even more obvious, and lagged.

"am i close or heading off on one?"
I think you're close mostly, someone else will explain more and better than I can though.

edit: I agree with what Steve says too, our posts reflect the same things really

ps - It's hard to know the sealed sound well as most drivers have their parameters tailored for ported loading, and these days nearly all reasonably priced commercial speakers use ported loading. This is for the excitement in 10mins listening in a dealers dem room - I'm sure of this.

[Vikash]

Talk of ported enclosure being washy, lagging, smearing etc is rubbish IMO. If it's done corectly, a ported enclosure has other advantages in addition to extended response, such as less excursion near resonance which results in less distortion. Selaed vs ported is an aged argument, and neither is definitively better than other. I suggest reading up on the basics from the resevoir of sealed vs ported discussions that already exists. If it's your first design, then sealed it should be for simplicity IMO.

[5th element]

Simon you basically covered it all anyway.

Sealed matches with room gain better then ported, sealed has no farting port to consider. Sealed has better transient response so subsequently can "start and stop" faster, bass lines not smearing and all that. I'd much prefer to have high quality bass that may not go quite as low, then low bass thats not tuneful.

A ported enclosure however, if designed well, can sound really really good, if they were that bad manufactures wouldnt pick them all the time.

If you look at the impulse response for the sealed and ported boxes, there is not much in it. Both the sealed and ported have a very similar response, the sealed being marginally better.

However the group delay for a ported enclosure is significantly worse. The dealy doesnt go above 2.8ms in the sealed inclosure, but in the ported reaches 2.8 at 93hz and increases to 12.5ms at 36 hz. Im not 100% technically minded when it comes to these things because I have not studied them in depth but I do know that the sealed cab performs better on paper and in real life, most DIY'ers go for sealed bass if its to be high quality, if they can. Ofcourse if you really want maximum extension as per HT where quality is not the main concern, ported offers good advantages.