Which 6.5" mid-bass for a sealed box?

This good 5.5" is avaliable at Soundimports in 8 ohms to make this https://www.speakerdesignworks.com/finalist-monitor . Change the NLA tweeter by this

Wavecor TW030WA12​

iT should go a little cleaner in the low end than the Morel cat378 here due to the low cut off. Some adjustments will be needed. The impedance of the low end of this Curt Campbell design is at 5.5 ohms.

Hummm, vented design... I forgot ! But hey, not by luck it is vented !

I myself purchased 4 of this midwoofers cause I wanted to make a Curt Campbell MTM with the littliest NE128 now NLA and a 12" for the bass. After some private chat with @profiguy I went to the NE149W for a MTM or a MT. This is the Revelator of the ligth wallet guys .

A sb26 CDC in a 5" WG migths work too.
 
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I'm debating whether to add a little more height to the aluminium sides. This would take the enclosure size anywhere up from 20 to 30 litres.

It's mostly a case of being able to use an 8" driver with a tweeter in a waveguide. But looking at Fr graphs of waveguided tweeters they all appear to have a suck-out around 10K. So I'm asking myself if waveguides are really the solution or just a kind of fashion accessory.
 
it is better cause it is easy to reduce the volume if needed by adding plain bricks or sand bags . Make once, spend once !

However as already talked in the thread a ready made design is made for a precise front baffle dimension. So the design of the filter must be reworked according the size of the new enclosure.
 
I'm debating whether to add a little more height to the aluminium sides. This would take the enclosure size anywhere up from 20 to 30 litres.

It's mostly a case of being able to use an 8" driver with a tweeter in a waveguide. But looking at Fr graphs of waveguided tweeters they all appear to have a suck-out around 10K. So I'm asking myself if waveguides are really the solution or just a kind of fashion accessory.
Another option could be a WAW system using the 8" peerless you mentioned in a previous post in 30L and a full range like the peerless TC9 (or FaitalPro 3F22/25) with XO at 400-500Hz.
 
But looking at Fr graphs of waveguided tweeters they all appear to have a suck-out around 10K. So I'm asking myself if waveguides are really the solution or just a kind of fashion accessory.
What graphs did you look at? Here they are quite OK. But stating that you are thinking of them as a fashion accessory shows you have to do some more reading on the importance of directivity control in loudspeakers.

It basically boils down to: getting the sound pressure level (SPL) vs frequency on axis right AND getting the sound power level vs frequency right, or rather, in the right ballpark. That is important, because at mid-high frequencies (say 500Hz to 4kHz), both direct sound from the loudspeaker and reflected sound from boundaries in your living room will determine your perception of the sound. Things have to be in balance over a broad frequency range, without sharp changes.

For now, just accept that you have to address the subject. An 8" or 6,5" will beam the radiated sound forward at the crossover frequency by default. A bare dome tweeter does not. Think of a spotlight vs. a floodlight. Matching them eiher gives you an on axis suckout at the crossover frequency or quite some excess sound power just above the crossover frequency.

Now here comes the waveguide. That starts to beam the tweeter sound from 1,5 to 2kHz for standard waveguides like the WG300 or the WG148, the two most easy commercially available ones. So with them, you get a match in directivity between woofer and tweeter and a far better starting point for a really good loudspeaker system.
 
markbakk - I see you are a fan of waveguides. I was being a bit lighthearted by calling them "in vogue". I know the directivity argument. I'm not sure it applies so much in my case since most of my listening is ambient in the room, not with me sitting carefully between the speakers. I usually listen when I'm doing other things. So soundstage doesn't mean that much to me. Tone and detail do. I'm a bit concerned by the drooping treble response I've seen in a few Fr graphs. I'm not dismissing a waveguide - I'd like to know more about what happens around 10K, especially off axis.
 
I‚m not a fan of waveguides, but of directivity control. Long ago I always liked 3-way or 4-way systems better. Now I know a very probable cause.
As I wrote before, you don’t need waveguides, but the alternative is very careful planning and optimizing the cab shape. Not some shoebox-design without any attention for even dispersion. Read Toole, Geddes or have a look at Erin‘s site. Or look again at the sites of Heissmann and Gresler, aka Donhighend.
 
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Centro-Cultural-Brasileiro ?

Well at Stereophile they made half of the job cause they do not open the loudspeaker they test. Maybe the coil and caps are directly soldered on the insside aluminium cabinet ?!

changing the tweeter cap would have given an identical result I surmise for few (paper in oil something). Or maybe the Beyond cable is made of aluminium too ? 🤔

I advice Rembrandt cables for charioscuro effect !
 
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Another option could be a WAW system using the 8" peerless you mentioned in a previous post in 30L and a full range like the peerless TC9 (or FaitalPro 3F22/25) with XO at 400-500Hz.
I'm curious as to why you chose 400 - 500 Hz for the crossover, purely because I've partway to completing a WAW project, intending on crossing over much lower ( perhaps even 90Hz) when finished, but as a temporary measure I have connected it up to crossover at 500, and I'm pleasantly surprised at the result.
 
The Fs of a 3-4" driver is around 100-150Hz and it's better to have your xo frequency over 300Hz. Crossing it over that frequency you reduce the distorsion too.
I prefer to have the range 250-3000Hz (thelephonic band) reproduced by a single driver but at the lower limit you need a bigger driver and you have to manage the baffle step attenuation, whereas at the upper limit a bigger driver is beaming. A classic case of short blanket and a compromise is needed. One of many.
 
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It's feasible from 250 hz with a 10F/ from ScanSpeak. But it is too much little for a living room midfield system with so low cut-off. T Gravsen lately after used it in 3Ways classic think it is a little small below 800 hz and switched to bigger size for its 3 was classic concept.

this driver should be horned.
 
A classic case of short blanket and a compromise is needed. One of many.
That's what I'm finding. Rough guide crossover at 2xFs or so. Similar to what some suggest for tweeters but some of those appear to able to go lower. Idea appears to be get well past the electrical phase shift at resonance.

Bigger the mid the sooner it has significant beaming. SPL. I picked a dayton 90mm. It can produce 85dB 1 watt at 100Hz. Xmax limits it to that at 100Hz. Crossover higher and more is available. Looks like a bad choice as significant cone problems at 3Khz.

I'm thinking of running the mid sealed - good idea or bad pass but know some commercial designs have done that. The enclosures can be pretty small.
 
I‚m not a fan of waveguides, but of directivity control. Long ago I always liked 3-way or 4-way systems better. Now I know a very probable cause.
As I wrote before, you don’t need waveguides, but the alternative is very careful planning and optimizing the cab shape. Not some shoebox-design without any attention for even dispersion. Read Toole, Geddes or have a look at Erin‘s site. Or look again at the sites of Heissmann and Gresler, aka Donhighend.
Getting an higher directivity is just almost close to impossible.
Especially with anything that is => 6 inches.

That is just inherent in how dome tweeters work and physics of the dimensions of any sound source basically.
It could work with well made 3 or 4 inch fullrange drivers.
But that brings yet another set of compromises.

Which is another tango dance we have to take, since some rooms (read: quite A LOT) have quite some pesky reflections we can't get rid of.
So unfortunately we have to decide; are we gonna tolerate those reflections, or go with a higher directivity and therefor the need of a waveguide.
 
SO, since 5" you are telling us to use a WG to narrow the room reflexions from the tweeter. Did I understand well what you wrote ?

Many people are saying 6" is the ideal size trade off to experience good dynamic and soundstage at home while needing a WG for the tweeter.

Do you agree for a 3 Ways or one can go lower mid say 3" to 5" with different low pass cut offs. What the best acccording your experience ?

I assume with 3" FR the tweeter if handing the 3k plus area, you do no need tweeter (cause the 3" spread wide till this area) ?
 
A 5 inch just falls on the edge.

I personally still would like a waveguide, just because it will just make the directivity better as well as lower the distortion significantly around 2-3kHz.

A 6 inch will be more beneficial for the low end and/or providing a bit more SPL.
Or in a simple 2-way supported by subwoofers, the distortion is often better around 100-150Hz.

I don't find a classic 3-way system that beneficial anymore these days, except when you only can have two passive speakers in the room.
(or just like them for subjective reasons).

I personally wouldn't use an additional tweeter with a good performing full range. It mostly messes up a good directivity.
On the other hand dynamic range can be limited, so I would go for a micro array or so.
A lot of modern fullrange drivers go up to 15-20kHz without to much trouble and can be used from 200Hz-300Hz.
They will produce a lot more distortion and IMD when being crossed lower.
But just check distortion graphs, there are some exceptions.

I don't think there is any best solution, they all have pros and cons and it really depends per use case and budget.
There are also always exceptions plus it all depends what your personal preference and situation is.
 
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I've found this thread interesting in terms of which 6.5" to use in a 2 way. Why 6.5. Correct choice and it can have some degree of bass response. Beaming comes next. This is the plot for the w170s
https://www.visaton.de/sites/default/files/dd_product/w170s_rd.gif
This speaker appears to have a lack of cone problems up to a fairly high frequency. So say it crosses over to a tweeter at 3kHz. The tweeter starts contributing before that and the 170 less after that. The net effect is a polar response similar to the one shown in the image for 2kHz. Not perfect but not as bad as might be expected.
Tweeter - probably something like this which appears to be good for a 25 even compared with some smaller
https://www.visaton.de/sites/default/files/dd_product/g25ffl_rd.gif
I have read that some are about intended to come in at a much higher F. Probably only suitable for 3 or more ways.

How big do speakers need to be? I have to wonder why this set up but an earlier version can very easily exceed the sound levels we use in the lounge.
https://www.soundimports.eu/en/hivi...5ihNHxNJ3Qg_TYkexcWXL9Be_s7-ZODBoCwRMQAvD_BwE
Bass comes in at ~40Hz. At realistic settings the cone is not bouncing about. It could be made to as near field stuff often has the ability to chuck more power into the woofer but I want what was there in the original recording. My previous kit was pretty well regarded but optical set up complied with the Sony Phillips spec and Linux decided that Pulse needn't be permanently resident. Pops that were rather loud every time Pulse fired up. The sound quality from the Swan kit is pretty similar 😉 no pops It can be driven via wire with no noise problems. No chance what so ever on the previous kit.
 
Box is taking shape. Final size of frame is 390 x 275 x 250mm, approx. 25 litres. Can use up to an 8" driver.

Now need to start putting it together and making a front and back.

MyAlu25ltr.jpg
 
You've influenced me Andy. I've finished a design of a 6 1/2 inch with a 20L box, vented as sealed wouldn't go as low as I want. 😉 I'm trying to imitate a now ancient AR-6. F6 40Hz. Name a style of music and I will have heard it through those and also been able to compare with live and concerts. Even opera.

Crossover is at 2.4kHz. I looked at 8" and found it would need to be a fair bit lower. Some would want over 3k but it looks like 3 way may be a better route for that. Sealed gave me an F6 of 50Hz, 50L vented could give an F6 of 30Hz. A tower a bit over 1m high. The AR-6's did it in 15L sealed by using a very low FS driver,

🙂 No excuses not to build now but I do want to look at different crossover arrangements that don't result in impedance peaks or at least only moderate ones. They exist but have no idea how they are done, If I fail I'll just go with what I have, These speakers have to be connected to a Class D amp. The speaker impedance helps damp the filtering on these, 😉 Seems this feature can be designed out of the amps however afraid I wonder,