Best loudspeakers design? Myth?

Trist

Member
2001-07-13 5:32 am
If you look at really exspensive speakers, B&W, Wilson Audio, Martin Logan, German Physiks and other high end speakers, you notice that none are the same. No two companies share the same basic design feature. So how on earth are you suppose to come up with the perfect speaker design, when there seems to be none to follow? I want to build an amazing pair of speakers for myself, but i got no idea what an amazing pair of speakers is made of.

I could build a corian box, that look's like the Watt/Puppies, and put in two 8", a 6.5" and a tweeter.

Or i could build a snail shape box, and put in lots of speakers.

But what is the best?!?

two 8" drivers, or one 15" for bass?
A mid and a mid/bass, or just a mid/bass?
A corian box, or a MDF/SAND/MDF sandwich?
A box design, or a odd shape design, like a sphere?
A down firing port, or a rear firing port?

It's driving me mental..

I know i have to build speakers to my music taste (acid jazz, trip-hop, electronica).. but ehh... so yeah.. any suggestions on what to build? The budget is not a matter..
 
heh. if you figure out the answer to this problem, let me know!

I don't think anyone out there can agree on what the best speakers are... they each have their strengths and weaknesses, and there are many schools of thought about which properties are most important... frequency response, phase response and time alignment, THD, IMD, polar patterns etc...

...and of course you'll want to choose something which suits your music, and the room you'll have these speakers in, since the room is really part of the enclosure.
 
Just to let you know, although two 8 inch drivers may produce tighter, faster bass, using multiple drivers of smaller size cannot produce low frequencies as deep as larger drivers. You must move a large amount of air softly, not small amounts of air violently, in order to achieve low bass.
 

kelticwizard

diyAudio Moderator Emeritus
2001-09-18 2:33 am
Connecticut, The Nutmeg State
Super:

Two 8" speakers have approximately the same cone area as one 12" speaker. Assuming that they have the same back-and-forth excursion and are identical in all other respects, are you saying that the 8 inchers will not produce the bass that the 12 incher would?

I realize as a practical matter, most 12's have greater excursion than most 8's. Still, let us say that the excursion, along with everything else, is identical.
 
As a general rule, the free air resonance (F3) of 8" or 10" drivers won't be as low as that of 12" drivers. To a first approximation, the free air resonance of a driver is going to be about the lowest frequency that you can expect it to reproduce. If it were purely a question of the amount of air moved, all would be well, but once a driver begins to roll off, you have to resort to extreme measures such as increasing the drive to the driver to compensate for the decreasing output. Of course, the same trick can be used for 12" drivers, so they still win in the end.

Grey
 

Trist

Member
2001-07-13 5:32 am
Ok, so two 8" won't go as low as one 12", but two eights would be better than one 8" right? And three 8" would be too much right? I think so..

So right now, my current design is a 1" dome tweeter, 6.5" mid bass, and two 8" subs.

I'm hoping it will give me amazing mid (voices and ambient sounds).. not to strong highs (the B&W Nautilus 801 have horrible high's i find, because they cause discomfort whenever someone says a word with an "S" in it.. it makes that "ear bleeding" pain.. but that might just be the pre amp's fault) and good, qucik but not excessive bass... like car sub bass.. blerk.

Anyone have any comments on the driver set up?

And i'm thinking about porting both the subs and the mid.. would anyone tell me why sealed might be better? just curious.
 

kelticwizard

diyAudio Moderator Emeritus
2001-09-18 2:33 am
Connecticut, The Nutmeg State
Nothing wrong with the set up. Everything depends on which drivers you use.

Venting the mid might be tricky-or it might be a good idea. Thing is, the mid is carrying the vocal range-lots of fine detail. Vented designs tend to have a certain amount of distortion. I greatly prefer vented designs for bass reproduction, where the inherent "overshoot" is basically inaudible, and more than compensated by the cone's being relieved of the necessity to travel very far. In the middle ranges, though, it introduces distortion.

Venting the mids might be good if you don't go above 150 Hz for your crossover-your vent should be tuned to 150 Hz. or so.

I would not vent if you cross over at 300 Hz. You will be smack in the middle of the vocal range. Middle A is 440 Hz.
 

kelticwizard

diyAudio Moderator Emeritus
2001-09-18 2:33 am
Connecticut, The Nutmeg State
PS:

If you are going to cross over higher than 150 Hz., (or even if you aren't), and you want a nice sharp sounding mid, a sealed system with a final Q lower than 1 is very good. A final Q of .7 gives very good transient response, that is, a smooth, undistorted sound.

If you have a driver in mind, I can give you the box volume that will produce a final Q of .7 for the mid. I don't have a link handy that deals with closed box systems.

I have heard of some system designers that design for a Q below that-even down to .5. Better transient response still.
 
Building Materials & Multiples Vs Singles

Trist, There are many facits to your questions. What is absolutely predictable is the amount of discussion involving the question of which is best: one big woofer, or two or more smaller ones. Let me address this first. I have made and used both in the past, and I like both paths. However, their charactistics are somewhat different and work best in different applications. If you want to get the lowest rumble from Jurassic Park where the T Rex goes crazy, then a single large woofer will work best. If you want lows that are smooth and easy to pick up with the greatest amount of clarity, then the multiples are best. Since two 8" drivers have more than twice the cone surface area than a 15" woofer, in theory, the two 8" woofers would do a better job. But keep in mind that Xmax works to the 15" drivers advantage. Subwoofers can push that air a lot more by moving further, but their frequancy range is lower and limited. But the one thing that they can't do is recover as quickly as the 8". This means that the smaller woofer's transient response is better, and in my opinion more practical in the real world. Also, the floor area that the multiple friver speakers take up is less than the bigger one. Also, the cost is generally less than with the super duper drivers and their gigantic enclosures. However, in the end, the decision is yours to make. That is why I have two sets of speakers in my living room: one for home theater and one for listening to music. Guess which one is used for which? I'll talk to you aboutg the Corian tomorrow, as it is late and This intrigues me. Later. John L
 
Have not got any good answer on your question, but I have built at least 30 high-end designs the last 20 years and might give you some hints.
If you are going for a 1" tweeter there is no better than Theil & Partner C2-12. I have tested most other fron Focal, Dynaudio, Scan-speak etc and none have the clarity and even dynamic sound that C2-12 have.
Midrange should be 6,5" or 5" if you plan to use a 8 or 10" bass. I have tested at least 25 different midrange drivers from different brands and best so far is Vifa P13.
The box volume for the midrange should be kept smaller than
5 liters and ideally 3 liters to get the best "tone".
Bigger boxes for the midrange will always give too much
colorations. In my own reference I have a 3 liters box where the rear wall is substituted with 10 cm with hard rockwool. Getting rid of those reflexes is a nice ticket to a extremely good midrange. If you test this make sure you have no leakage and enough of rockwool to prevent front to rear cancelations. If you also round the edges of the baffle to radius 40mm Vifa P13 will give a +/-1dB from 200-6500 Hz which gives a really impressive midrange that few commercial designs can compete with.

Hope this gives a push in the right way.

/Janne
 
Hedlund (and any one else interested)

Are you talking about the P13WH or the P13MH ??
Which subs would you partner them with: M18 or P21 ??
What about P17 instead of P13 ??

Would be interested to hear your experiences with these drivers in this type of setup.

My choice for tweeter looking like D2905/9500 though could be swayed by newer Vifa Premium Line soft dome 27mm if any good (yet to hear it). Have heard that some of the more recent Vifa tweeters have inconsistent f-res. But... a lot cheaper than Scanspeak !

Simon.
 
>>Are you talking about the P13WH or the P13MH ??

I'm talking about P13WH-00-08.

>>Which subs would you partner them with: M18 or P21 ??

The best so far is Vifa M26WR-09-08 in a passive radiator
with a loaded Scan-Speak 25W/8565-00 as drone cone in a 50 liter box.
Every time I have used a 10" bass it outperforms any 8" type, because of the extra deep bass and less motion the cone need to do. (less distortion). Usually I use them up to around 250-300Hz and their break-up usually don't occur until over 1000Hz so they match perfectly with a 5" driver.
The configuration I use have a "in-listening-room" response of +/-2,5 dB from 27-650Hz with very low distortion.

>>What about P17 instead of P13 ??

They sound nice, but need a bigger box which gives more colorations, sound "plastic" and gives much less "air" to the midrange. Most 6,5" drivers also have a tendency to give a slightly compressed sound from 1500Hz and up.
Vifa P13 don't have this problem until it reaches 3000 Hz and if you use a "normal" crossover at 2500 Hz the problem is almost gone.

Regarding tweeters you won't get a upgrade with Vifa's Premium Line tweeter. Stay with your Scan-speak or change to Focal 120 type. If you want the ultimate use Thiel & Partner C2/12 which have the transparency and resolution of Dynaudio Esotar but with a more linear response which give a over-all better sound.

>Have heard that some of the more recent Vifa tweeters have
>inconsistent f-res. But... a lot cheaper than Scanspeak !

The Vifa tweeters I have used have measured fine and even but sometimes not according to their datasheets.
Most of the tweeters I have bought from Seas have this Rf problem though. I don't know if it's bad luck or a result of low production quality.

/Janne
 
Hedland wrote: "If you are going for a 1" tweeter there is no better than Theil & Partner C2-12. I have tested most other fron Focal, Dynaudio, Scan-speak etc and none have the clarity and even dynamic sound that C2-12 have."

If I can't get my hands on the Theil & Partner C2-12 tweeter, what are my next best options? Supply wise, my most likely candidiates are products by Vifa, Peerless, or Scan-speak.

Thanks.
 
Trist said:
If you look at really exspensive speakers, B&W, Wilson Audio, Martin Logan, German Physiks and other high end speakers, you notice that none are the same. No two companies share the same basic design feature. So how on earth are you suppose to come up with the perfect speaker design, when there seems to be none to follow? I want to build an amazing pair of speakers for myself, but i got no idea what an amazing pair of speakers is made of.

I could build a corian box, that look's like the Watt/Puppies, and put in two 8", a 6.5" and a tweeter.

Or i could build a snail shape box, and put in lots of speakers.

But what is the best?!?

two 8" drivers, or one 15" for bass?
A mid and a mid/bass, or just a mid/bass?
A corian box, or a MDF/SAND/MDF sandwich?
A box design, or a odd shape design, like a sphere?
A down firing port, or a rear firing port?

It's driving me mental..

I know i have to build speakers to my music taste (acid jazz, trip-hop, electronica).. but ehh... so yeah.. any suggestions on what to build? The budget is not a matter..

4 8s and 2 15s

4 mid basses

corian/sand/corian

A box that looks odd

a down firing rear port
 
Re: Building Materials & Multiples Vs Singles

John L said:
Since two 8" drivers have more than twice the cone surface area than a 15" woofer, in theory, the two 8" woofers would do a better job. But keep in mind that Xmax works to the 15" drivers advantage.

Check your maths. An 8 has a cone area of 50.2 sq in (therefore two is 100.4 sq in), a 12 has 113.1 sq in. A 15 has 176.7 and wins hands down.

John L said:
Subwoofers can push that air a lot more by moving further, but their frequancy range is lower and limited. But the one thing that they can't do is recover as quickly as the 8". This means that the smaller woofer's transient response is better, and in my opinion more practical in the real world.

This is a common misconception. The larger/heavier cone can have equal and even better transient response than a smaller driver if it has the motor assembly to cope. Transient response is a function of Qts. If a 3 inch driver and 15 inch driver have the same Qts but massively different moving mass, and the same Fs (impossible I know, but for the sake of argument) then they will sound the same. Of course, the smaller driver also has much lower efficiency.


Regarding the original question, my personal preference would be to go with a single larger driver for the bass. IMO a pair of 8s will not offer all that much more over what the 6.5 mid could possibly be capable of. No matter how many 8s you use the F3 will still be the same, whereas if you use a 10 or 12 you will more than likely get lower.