Best size mid-bass for a 2-way?

[MVJ]

First time I've heard that description of a pair of speakers. I haven't the faintest idea what this may mean?

To many mushy peas

 

[Tony_J]

First time I've heard that description of a pair of speakers. I haven't the faintest idea what this may mean?

Big t**s...?

 

[Nopiano]

I have the Revel M16, they're a 6.5 inch bass driver rather than 8 inch surely?!

Apologies, you’re quite right. That’ll teach me for thinking I’d remembered.

I’ll edit my earlier post.

 

[Nopiano]

First time I've heard that description of a pair of speakers. I haven't the faintest idea what this may mean?

I was meaning a bit overblown, boomy if you like. But I see it really means coarse or untidy.

Untidy is good. Not smooth, tapering bass, but a bit untidy sounding. Trying too hard.

Nothing to do with blouses!

 

[pmcuk]

Well, I've been living with my new Mission 761 speakers for a few days now and I couldn't be happier. Mid-bass is an old 6.5" 165mm from Vifa, no longer made since this dates from early 90s. Tweeter is the famous and widely used old Vifa D19TD which is very crisp and clean. Classical music and opera is very detailed with really nice tone.

So this is a step up from my Wharfedale Program 30D-6 speakers with B110 size mid-bass units which are effectively 5.25", 150mm according to their SD. This would be the case also with all the LS3/5A clones.

What can I say - size matters! I'm absolutely convinced by the 6.5" mid-bass. There remains the concept of an 8" mid-bass but I don't think I'll be going there. But who knows. At least 6.5" is where the quality starts in a 2-way with no subs from what I am hearing.

 

[tuga]

I was meaning a bit overblown, boomy if you like. But I see it really means coarse or untidy.

Untidy is good. Not smooth, tapering bass, but a bit untidy sounding. Trying too hard.

Nothing to do with blouses!

Both Audioholics' and ASR's measurements show an exaggerated low end (bump):

https://www.audioholics.com/bookshelf-speaker-reviews/revel-concerta2-m16/measurements

 

[Nopiano]

Both Audioholics' and ASR's measurements show an exaggerated low end (bump):

https://www.audioholics.com/bookshelf-speaker-reviews/revel-concerta2-m16/measurements

Thanks! I’ve not completely lost it then? My hearing that is.

 

[Beobloke]

I have the full set of 1990s Goodmans Maxim, Mezzo and Magnum with 5”, 6.5” and 8” bass drivers respectively, and all the same tweeter.

The Magnum sounds the best. Make of this what you will!

 

[pmcuk]

I have the full set of 1990s Goodmans Maxim, Mezzo and Magnum with 5”, 6.5” and 8” bass drivers respectively, and all the same tweeter. The Magnum sounds the best. Make of this what you will!

That doesn't surprise me. I've been checking the stocks of the UK DIY speaker companies and the 8" are listed as woofers not mid-bass speakers. There are a number of good mid-bass units with 145mm cutouts, which is a standard. The OD ranges from 165mm to 180mm. Some very good ones from Scanspeak, SB and Vifa-Peerless. They seem to have chosen this size for their flagship mid-bass ranges like Revelator, Illuminator, Sartori etc. costing hundreds of pounds.

8" woofers were all the rage in the 1990s, in fact from KEF onwards, but 6.5" to 7" seem to be the current favourites.

 

[tuga]

That doesn't surprise me. I've been checking the stocks of the UK DIY speaker companies and the 8" are listed as woofers not mid-bass speakers. There are a number of good mid-bass units with 145mm cutouts, which is a standard. The OD ranges from 165mm to 180mm. Some very good ones from Scanspeak, SB and Vifa-Peerless. They seem to have chosen this size for their flagship mid-bass ranges like Revelator, Illuminator, Sartori etc. costing hundreds of pounds.

8" woofers were all the rage in the 1990s, in fact from KEF onwards, but 6.5" to 7" seem to be the current favourites.

There are two reasons for using a 5" to 6.5" mid-woofer:

• the most important one is directivity matching - a larger diametre driver will have narrower directivity than a smaller one and that will produce a dip in the crossover to tweeter region off-axis (horizontal)

• the second reason is (narrow) baffle width and WAF - no WAF, no sales

 

[rabski]

There are two reasons for using a 5" to 6.5" mid-woofer:

• the most important one is directivity matching - a larger diametre driver will have narrower directivity than a smaller one and that will produce a dip in the crossover to tweeter region off-axis (horizontal)

• the second reason is (narrow) baffle width and WAF - no WAF, no sales

With this in mind, how about a D'Appolito layout with two slightly smaller mid-bass drivers? Complex to DIY, I would imagine, but seems to offer some advantages. Some of the nicest sounding speakers I know use multiple smaller drivers for mid/bass rather than one large one.

 

[tuga]

With this in mind, how about a D'Appolito layout with two slightly smaller mid-bass drivers? Complex to DIY, I would imagine, but seems to offer some advantages. Some of the nicest sounding speakers I know use multiple smaller drivers for mid/bass rather than one large one.

Sounds good to me. It will improve directivity and sensitivity.
Something like this maybe?

https://arendalsound.com/types/monitor/

I hope that @pmcuk hasn't started his shopping because I feel that it would be beneficial to set out a proper design brief beforehand.

Things to consider:
• Budget
• Target bandwidth, max SPL and sensitivity
• Cabinet design: size, topology - sealed or ported, construction
• Driver topology: number of ways, number of drivers, crossover design, directivity control (waveguide, coax)

Most important/audible aspect is tonal balance, which results from a combination of frequency response (on-axis response), directivity (off-axis response) and cabinet diffraction.

 

[pmcuk]

With this in mind, how about a D'Appolito layout with two slightly smaller mid-bass drivers? Complex to DIY, I would imagine, but seems to offer some advantages. Some of the nicest sounding speakers I know use multiple smaller drivers for mid/bass rather than one large one.

Sure - many nice MTM. In my case I'm trying to keep things simple with a 2-way. But MTM effectively gives you a "larger" bass unit so better bass. Popular way to do it. Does cost more in mid-bass units, though.

Have I started shopping? No, not yet. I'm very happy with my new Mission 761 and one thing I want to think about is ported versus sealed. The 761 is sealed which in theory is my preference.
Bass response would vary accordingly, but I don't need deep bass, just enough. I've pretty much decided on an aluminium cabinet, that's a bit of a no-brainer for an added £100 or so. I've pretty much decided on a 6.5" to 7" mid-bass in view of the quality of the available units from Scan, SB and Peerless. No idea of tweeter but I have a short list of 1" models. Crossover will be around 2.5-3K depending on units. Budget would be under £100 for each mid-bass, which is easily done. Tweeters are usually around £50 each. Not worried about SPL or sensitivity with these designs. I intend to build an existing and well reviewed "kit" from Troels Gravesen, Jeff Bagby etc. So I'm close to shopping. One of the main decisions is ported versus sealed, still pondering on that and listening to my 761s.

I'm a retired academic amongst other things, and believe me, I do overkill amounts of research. I have multiple Excel spreadsheets, Image files and Word files with lists of units and data and archived posts from DIY Audio etc. I want to know everything before making a move.

 

[tuga]

Sure - many nice MTM. In my case I'm trying to keep things simple with a 2-way. But MTM effectively gives you a "larger" bass unit so better bass. Popular way to do it. Does cost more in mid-bass units, though.

Not only more bass extension and less low-end distortion but also higher sensitivity and better directivity characteristics.
You'd probably get away with 2no. smaller midwoofers.

 

[Tony_J]

With this in mind, how about a D'Appolito layout with two slightly smaller mid-bass drivers? Complex to DIY, I would imagine, but seems to offer some advantages. Some of the nicest sounding speakers I know use multiple smaller drivers for mid/bass rather than one large one.

...including Living Voice, for example...

Actually not much different to DIY other than they tend to be a bit taller to keep the tweeter on ear level.

 

[hiesteem]

I was listening to Alan Shaw talking about developing tonal accuracy by first listening to his pre production drivers through human voice. His reason for this approach as opposed to music is that all music is processed and consequently he listens to music at a later stage of the process.
Another interesting point is he feels the sweet spot for cabinet design and he mentions quality bass is 24 by 12 and 12.
I thought about that and this seems to be an old application for some of the well researched BBC designs.
It does seem that the ls8/1 ls3/6 and Harbeth hl5 all major on mid range with good bass extension.

 

[pmcuk]

... he feels the sweet spot for cabinet design and he mentions quality bass is 24 by 12 and 12.
I thought about that and this seems to be an old application for some of the well researched BBC designs.

24"x12"x12"? That's about 40 litres internal. That's big. The problem with going big is that the cabinets resonate more and more and need complex bracing etc. Not to mention the space taken up. I presume he means sealed box, like they used for the KEF B200 and B139. It would need a large bass unit 8" up.

Easier box construction with 20 litres or less, and the bass is still pretty good even in a sealed box with a 6.5" mid-bass with Qts above 0.4.

 

[bencat]

I would suggest that 8" is the best compromise size between extension and cabinet size . My preference is the SP1039 KEF 200 which is what is in my KEF 103 Reference speakers . In passive mode as a two way they sounded excellent . Thye improved when used as a two way active . The stacked active pair I use now moves them in to another area and sounds amazing to my ears . KEF in the 103 got round the larger cabinet being resonant by using and internal metal frame and stick on pads seems to work well but they are a little heavy .

 

[pmcuk]

I would suggest that 8" is the best compromise size between extension and cabinet size . My preference is the SP1039 KEF 200 which is what is in my KEF 103 Reference speakers . KEF in the 103 got round the larger cabinet being resonant by using and internal metal frame and stick on pads seems to work well but they are a little heavy .

I was just looking up threads on the B200 this morning.

http://www.t-linespeakers.org/drivers/b200.html

https://www.diyaudio.com/community/threads/b200-kef-drivers.3960/

http://www.hifiloudspeakers.info/speakertalk/viewforum.php?f=1

Hmm - internal metal frame. Interesting. I'll have to look that up. You can still get the old 1970s models on eBay. Some were sealed box - Chorale III, Cantor (orig), Coda III, Coda IV, Coda V, Corelli. I don't know if I'm tempted. Enjoying my new Mission 761s which are sealed box as well. I'm rather liking sealed box.

 

[hiesteem]

Yes of course you're right about cabinet resonance and I was throwing in Mr Shaws thoughts from his design perspective for his hl5 speakers.
If you can develop your design from the box first then that would inform your whole design going forward.
I'm of the opinion regarding speaker design that the box is where most of the final results will originate from.