Midbass Diameter - How to Decide?

[Conrad Hoffman]

AFAIK, "midbass" refers to a midrange speaker with a bit more bass capability than is traditional, maybe a bit longer throw and higher power capability. Those Dynaudio units I mentioned are only about 5" on the cone, but have a 3" voice coil that can soak up a lot of watts. The trick, as always, is to get enough overlap in driver response such that a reasonable crossover is possible. My experience is that few drivers larger than 8" can successfully mate up with most common dome tweeters. The old Large Advent's claim to fame was that they managed to stretch the response of a relatively large woofer up to meet an equally down-stretched tweeter. IMO, everybody who's serious about their listening eventually reaches the conclusion that, though a 2-way can be very good, a well designed 3-way (or more) will beat it on bass extension, vocal quality and probably efficiency. I'm talking traditional boxes here, not electrostatics, Maggies, or groups of drivers like the old Bose. Also IMO, a small set of speakers with a subwoofer qualifies as another 3-way or more system.

[tinitus]

Long time ago I made a 2way fore a friend, with a very nice 8" Seas and a Thiel tweeter, and it sounded quite nice fore a number of years
Now suddenly he doesnt think the mids are clean enough
well, thats the price you pay fore using such a big mid
Though today I may be able to do better using a notch and so on, but its tricky to get absolutely right...possible, but not easy
But certainly, the right 8" can produce quite "musical" sound, not superclean, but nice

[Brett]

Define midbass first would be a good idea.

[tinitus]

In this case I understand it as a standard hifi driver that does the deepest possible bass from around 40hz up to the high mids around 2.5khz

[lineup]

if we are talking midrange drivers, we are into 3-way systems, right?

In such case I will go for a 4 or 5 inch driver .. woofer
But with one important reservation:
Very low FS, frequency resonance

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so
1. relatively small diameter, max 5" (100-125 mm)

2. woofer (not tweeter or dometweeter)

3. low FS .. above 100 Hertz is out of my question

4. high efficiency, sensitivity (I look only for SPL 92 dB or more)

5. robust and topclass mechancial construction = heavy, >= 1 kg (not less than 2 pounds!)
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When following my very tough criteria there are basically only 2 (two) Brands that comes into my play:

1. Focal ... world's best drivers for hi-fi audio
expensive! but worth every penny

2. Audax ... very good midrange drivers with high efficiency
a bot lower in price, but Audax top line is always something extra

Lineup Audio Speakers forum - members only can read our stuff!

[tinitus]

Originally posted by lineup
if we are talking midrange drivers, we are into 3-way systems, right?

[/B]

He clearly says 2way in his very first post

Fore using a 10" or even 12" midbass, why not consider Gedlees Summa kit, which has the benefit of a compression driver going as low as 1Khz

[tpsorin]

Single 5" will not give you enough bass in large room. I would not use 5" in rooms bigger than 25sqm. you will probably need a subwoofer

For a large room 2way, I would recommend 2x6.5", 2x7". Or you can try 2x5" transmission line.

[The golden mean]

Originally posted by lineup
if we are talking midrange drivers, we are into 3-way systems, right?

In such case I will go for a 4 or 5 inch driver .. woofer
But with one important reservation:
Very low FS, frequency resonance

When following my very tough criteria there are basically only 2 (two) Brands that comes into my play:

1. Focal ... world's best drivers for hi-fi audio
expensive! but worth every penny

2. Audax ... very good midrange drivers with high efficiency
a bot lower in price, but Audax top line is always something extra

Lineup Audio Speakers forum - members only can read our stuff!

Sorry,
Focal don´t sell drivers to the public except for car audio. Of course some drivers for this destination can be used at home.

Audax, they have been into problems and possibly manufacturing of some drivers are kept running by some employees. It has been some notes about this in the German magazine Klang+Ton.

Perhaps someone can translate this into English? I can´t read French but I guess the headline says "The site isn´t available right now" Correct?

Audax

[myhrrhleine]

Originally posted by BlueWizard
[B]I would take the opposite approach to what Myhrrhleine said, though the difference in our approaches is more philosophical than literal.

I would go for the largest speaker I could find that would still give me the high range I needed. Of course, this assume that it would also cover the bass range as well.

why?
given otherwise identical perfomance, why largest?

[J.R.Freeman]

Originally posted by BlueWizard
I would take the opposite approach to what Myhrrhleine said, though the difference in our approaches is more philosophical than literal.

I would go for the largest speaker I could find that would still give me the high range I needed. Of course, this assumes that it would also cover the bass range as well.

Also, I take some exception to the general use of the term 'midbass', though I think it is being used correctly here. To me, and I could be wrong, 'midbass' means Midrange and Bass. I recently read a thread where someone wanted 'midbass' speakers that were large, went exceptionally low, and were loud. I thought to myself, he doesn't want midbass, he wants bass speakers. Sorry, just rambling.

I think, and again -generally, speakers 8" or smaller are the only speakers capable of midbass. There are probably rare exceptions, but anything 10" and above, is pretty much a straight bass speaker.

That said, I would also agree with Tinitus, that speakers in the 5" to ~6" range probably give the best results. There are many commercial speakers in this range that have clear clean mids and solid bass. So, I think this puts you in the sweet spot; large enough for good bass, small enough for good midrange.

But, as others have hinted, there are so many variables that it is almost impossible to nail down to a perfect range or size of speaker. But, I still stick to my philosophy of picking the biggest speaker that will do the job within a user's selected design parameters.

Yes, I know ...rambling...rambling.

Steve/bluewizard

Thank you for the comment Blue Wizard - that wasn't rambling at all, I found it informative! I agree, the term 'midbass' is used too quickly sometimes. I might be off, but what I mean is a small woofer (or big midrange!) which would make for a nice 2 way, reaching down to 50 Hz or so, and being able to cross-over at 2 KHz or more. Your concept of largest driver possible is an interesting take on the problem. I share this point of view to some extent, as I've always liked 2 ways with 8" drivers. However, while considering designs for a 2 way studio monitor, the question of midbass diameter was to be revisited.

You mentioned 5" ~ 6" range. I have decided to give 6" drivers a second look, to get a feel for what is affordable in this range. My feeling is that on average, a 6" driver would perform better in the upper midrange, but give up some low end performance when compared to a similar 8" driver.

But this makes me wonder - is this generalization founded in fact? Will a smaller driver perform better in the upper midrange section (ie better distortion numbers, smoother response)? Or, is the truth in the data sheet? For example, say I have 2 drivers which are very similar in build. Same cone material, the 8 shall have more motor structure but more Mms so they'll balance and have the same Qts (in a perfect world!). We'll say the 8 can comfortable cover up to 2.5 Khz, and the 6 can do up to 3.5. Now I ask you, at 2 Khz, which will play the tone more accurately? I suppose what I am getting at is, generally, will a smaller driver cover upper-midrange material better than a larger, even if the larger is still within that range?

Hehe now I'm rambling!

Originally posted by Conrad Hoffman
AFAIK, "midbass" refers to a midrange speaker with a bit more bass capability than is traditional, maybe a bit longer throw and higher power capability. Those Dynaudio units I mentioned are only about 5" on the cone, but have a 3" voice coil that can soak up a lot of watts. The trick, as always, is to get enough overlap in driver response such that a reasonable crossover is possible. My experience is that few drivers larger than 8" can successfully mate up with most common dome tweeters. The old Large Advent's claim to fame was that they managed to stretch the response of a relatively large woofer up to meet an equally down-stretched tweeter. IMO, everybody who's serious about their listening eventually reaches the conclusion that, though a 2-way can be very good, a well designed 3-way (or more) will beat it on bass extension, vocal quality and probably efficiency. I'm talking traditional boxes here, not electrostatics, Maggies, or groups of drivers like the old Bose. Also IMO, a small set of speakers with a subwoofer qualifies as another 3-way or more system.

Hi Mr. Hoffman, I see what you're getting at about 'stretching' a driver's response. You've almost talked me into a 3-way system! But it makes me wonder which is the lesser evil: more crossover points of a 3 way, more bandwidth demand per driver of a 2 way? The system I am considering will use a subwoofer, starting from around 55 Hz down. So like you said, it is something of a 3 way system. But for the scope of this thread, I am concerned with the most accurate way to cover the range of 50 Hz or so on up. So nothing sub-sonic.

You do bring up an interesting point though, of keeping more drivers well within their range as opposed to less drivers reaching to hold hands at the finger-tips around the crossover point. But my feeling is a 2 way system for the 'mains' would probably yield the lowest coloration. However your influence may inspire me to reduce the size of my 'midbass' to something more of a midrange in size. Along with what Blue Wizard said, a 6" should be able to cover the middle band well.

***

Thank you to the rest who had something to add - I have read everything, but I am a slow typer, and it is dinner time . Quickly though, to Tinitus thank you for the suggestions but a 10" or greater 'midbass' (or woofer at this point) would conjure crossover tom-foolery beyond my 4th order (at best) mind! Tpsorin, your suggestion of multiple drivers to address SPL limitations sparks another interesting line of debate - which is better many small drivers, or few large? But in this context I am interested in the comparison of the performance of single drivers.

Jim