Two In One Speakers

[Solar Paul]

I am thinking of building some speakers. These would be my first but I did train as a cabinet maker some years ago and this would be an enjoyable project in my retirement. I have had some good gear in the past but I had to let some of this go when we downsized our home. I would like to upgrade our "minimalist" approach. Here is some background and few questions seeking assistance from the forum.

We lived in the US in the late 90's and I put together a system of Vandersteen 2CE signature series speakers powered by Quicksilver M60 monoblock valve amps and a Vandersteen 2WQ sub for extra base to get full range. When we got back to Australia, I used this as the basis for a home theatre / music system adding a Theta Casablanca II surround processer, a third Quicksilver M60 for the centre channel and Vandersteen speakers for the centre (VCC-1) and surrounds (VSM-1). This system was a good compromise for home theatre (with musical but not viscerally pounding bass) and music (not as good as with the original Quicksilver valve 2 channel preamp but acceptable) and I loved it. But it was physically big and difficult to fit into combined living AV spaces as we moved around and although tolerated by my wife I think it fair to say that this was only to accommodate her audiophile husband. The AV space in our current home is quite small and I downsized the system to fit – selling the 2WQ sub and replacing the 2CEs with Vandersteen VLR Wood bookshelf speakers and the 3 M60 valve amps (and another small amp for the rears) with a Rotel RMB1095.

Our “new” system fits our living space much better, but it doesn’t hold a candle sonically to the old one which I miss and I am exploring what I can do to get better quality sound and deep bass in our much smaller living space. Well, actually the space is quite large – 8.4 metres 28 feet wide by 6 metres 20 feet long with a vaulted ceiling 4 metres 13 feet high, but only a quarter of this is used for AV (with one speaker in a corner) and there is definitely no room for subs unless they are under main speakers. I am attaching a photograph of our living space.

I’ve been thinking about what would work for us and I’ve formulated a plan which I’d like to get some feedback on before I go any further. Here are the key points:

• I'm retired now and don’t have a big budget to make a significant upgrade
• I’m thinking of mini towers, preferably no higher than the bookshelf speakers on stands (870 mm 34”) with subwoofer driver/s under and main speaker driver/s above, with separate feeds from the preamp to the powered subs and from the Rotel amp to the main speakers. Externally there would be 1 cabinet (internally partitioned into 2 for sub and main) with a single grill to cover all
• From my research I am drawn to Rythmik Audio FM8 subwoofers – here are the pros and cons I am aware of:
  
  • Small volume with 2 x 8 inch drivers per side - would be a good base for the mini towers – their standard cabinet size is 290 mm 11-1/2"(W) x 510 mm 20" (H ) x 395 mm 15-1/2" (D)
  • Very good upper range – to 250 Hz. As I understand it frequencies above around 80-100 Hz can be localised so subs which output up to 250 Hz would be better suited to being placed under the main drivers
  • Very good musical bass
  • Their direct server system gets bass down to 20 Hz (-3db), not big bass for HT but I think good enough for me
  • Expensive – this would be the biggest outlay of the project
• I would swap out the Casablanca II, which is only 5.1 channels, for an Anthem AVM60 which offers 11.2 channels (I understand the Anthem is still quite good for music and is able to be set up to crossover between the main drivers and the 2 subs for both HT and music. I would experiment to find the best frequency to crossover – expect 100 to 200 Hz
• I am also drawn to single full range drivers for the main speakers on the basis that
  
  • It will be easier to fit a single driver will into a mini tower
  • No crossover will be needed
  • The FM8 subs higher top end would mean the main driver only needs to go down as far as the upper range of the subs (possibly 150 – 200 Hz). With no need for deep bass from these hopefully a wider choice of drivers and better quality/cheaper cost

It would be good to have input on the best way to getting better quality full range music and HT with rich, deep musical base (not loud or pounding) in our limited space (IE no big subwoofers). In particular it would be good to get feedback on the following:

1. Are mini towers with 2 speakers in 1 (powered subs and passive mains) a good approach?
2. Are there good alternatives to the Rythmik Audio subwoofers?
3. Would I be better going with a single “full range” driver or tweeter and mid/woofer plus crossover for the main speakers?
4. What drivers would be recommended for the frequency range of 200 Hz to 20kHz

I look forward to hearing back from the forum

 

[Duke]

Are mini towers with 2 speakers in 1 (powered subs and passive mains) a good approach?

For your situation, yes.

Are there good alternatives to the Rythmik Audio subwoofers?

Imo Rythmiks are excellent, and I say that as a competitor.

Would I be better going with a single “full range” driver or tweeter and mid/woofer plus crossover for the main speakers

"Fullrange" drivers do simplify things, but are limited in SPL capability.

Eyeballing your room layout, imo fairly narrow and well-behaved radiation patterns are called for. Then you can use toe-in to avoid the otherwise strong (and imo undesirable) early reflection off the left-hand side wall.

What drivers would be recommended for the frequency range of 200 Hz to 20kHz?

I suggest the Eminence Beta 10CX, ASC-1001 compression driver, and PXB2-2k5cx crossover. This is will give you good radiation pattern control, with vastly better SPL capability and power handling than a "fullrange" driver.

Put the Beta 10CX in about 16 liters (stuffed sealed box) and you can run it fullrange (no protective highpass filter needed) up to about 200 watts, which would take you up to about 115 dB at one meter. In this box the Beta 10CX will go down to about 90 Hz, and then your subwoofer section can take over below there. However if you DO use a protective highpass filter, that will improve the clarity at high SPLs.

Here's the back-story: https://www.eminence.com/great-uses-for-coaxial-products/

To save space AND improve performance for your application, I suggest building the toe-in into the speaker cabinet. At this page you can see something that I used to manufacture:

https://www.audiocircle.com/index.php?topic=78557.0

The aggressive toe-in combined with the well-controlled radiation pattern results in a solid phantom center image even for listeners who are well off-center.

Since you'd only need 16 liters for the coaxial, you'd theoretically be able to devote a fair amount of internal volume to a subwoofer system. So you might consider DIYing your own subwoofer section, assuming that's something you'd enjoy doing. But I said, imo the Rythmiks are excellent.

 

[Solar Paul]

Hi Duke,

Thanks for your detailed and thorough response. I have considered your suggestions and reply as follows:

• Firstly, just to clarify. I am proposing to purchase a Rythmik kit with 2 amps and 4 drivers and make the boxes to house these myself. I would simply extend the boxes above what is needed for the subs, partitioned off at that point, and house the driver/s for the main speakers in the top part of the box. Externally it will be one box with a single grill covering both speakers
  
  
• It doesn't look like the Rythm Prism concept you suggested will be a goer for us. It got knocked out on looks by both of us, although I understand the rationale and it appears to be a good technical solution
  
  
• I wasn't aware of coaxial drivers like the Eminence products you recommended. They look like a good way of getting better SPL but I’m curious to know if there is any loss of clarity or sound quality generally with this approach. Are you able to advise?
  
  
• I see that Eminence offer an 8 inch version (Beta 8-CX) of the driver you recommended. That would work better for me to match the 8 inch drivers in the subs and keep the face of the speaker as narrow as possible. I know that these wouldn’t get as low as the 10-CX drivers but as the Rythmik subwoofers are rated up to 250 Hz I am hoping that the 8-CX drivers will still work well, albeit with a higher crossover frequency with the subs. What do you think about this alternative and are you able to advise how many litres space there should be in a stuffed sealed box for the main speakers and what would be the suggested crossover point for these smaller drivers?
  
  
• Never having built speakers before I understand the concept of litres of space needed for sealed vs vented speakers but I don’t know if all such spaces are equal. I expect that there are other factors other than simple empty (or stuffed) volume. Are you able to recommend sources of information which could guide me to building good speaker enclosures? There are offerings of software to design enclosures, indeed I see that Eminence offer this software themselves. Is this any good or necessary? Your thoughts on this would be appreciated

 

[Duke]

I didn't realize the Rythmik was a kit! That is awesome. Do that!!

I'd recommend the Beta 10CX over the Beta 8X for the larger cone size and better low-end performance and especially because the crossover was designed specifically for the Beta 10CX and ASD-1001. Imo this would be a better solution than a comparably-priced "fullrange" driver, from the standpoint of clarity and SPL capability. For best clarity from a coaxial, protect the midwoofer from long excursions with a highpass filter.

This is by no means the only possible solution, but imo it's a cost-effective one, and somehow I got the impression that matters, correct me if I'm wrong.

If you are limited to 8" diameter mid-woofers then I don't have an off-the-shelf DIY recommendation. Imo your in-one-corner of-a huge-room placement is a situation where a radiation pattern that is uniform across 90 degrees or so, and can be toed-in, is highly desirable. Just about anything else is going to result in a significant early reflection on your left and nothing on your right (which may or may not bother you). If you go with conventional speakers, you might consider treating the reflection zone on that left-hand wall with absorptive material at least four inches thick. And if you go with conventional speakers, you'll probably want a center channel speaker so that the dialogue is on-screen for off-centerline viewers.

The internal volume I mentioned is a ballpark suggestion, you can probably be off by 15% either way and it's not a disaster, just different. You can make the walls non-parallel and/or use whatever damping material you want to.

The software that Eminence sells is designed by Harris Technologies, I think. I use it all the time for taking a quick look at woofer +box designs; I have other programs which go into more detail but they take a lot longer to use.

Best of luck with your venture, wherever it may take you.

 

[M00ndancer]

These would be my first but I did train as a cabinet maker some years ago

I'm following this thread with interest, mostly for the progress on the speaker building. I have no skills to build something like you have, but I like your approach.

...Our “new” system fits our living space much better, but it doesn’t hold a candle sonically to the old one which I miss and I am exploring what I can do to get better quality sound and deep bass in our much smaller living space. Well, actually the space is quite large – 8.4 metres 28 feet wide by 6 metres 20 feet long with a vaulted ceiling 4 metres 13 feet high, but only a quarter of this is used for AV (with one speaker in a corner) and there is definitely no room for subs unless they are under main speakers. I am attaching a photograph of our living space.

...I’ve been thinking about what would work for us and I’ve formulated a plan which I’d like to get some feedback on before I go any further. Here are the key points:

• I'm retired now and don’t have a big budget to make a significant upgrade
• I would swap out the Casablanca II, which is only 5.1 channels, for an Anthem AVM60 which offers 11.2 channels (I understand the Anthem is still quite good for music and is able to be set up to crossover between the main drivers and the 2 subs for both HT and music. I would experiment to find the best frequency to crossover – expect 100 to 200 Hz

It would be good to have input on the best way to getting better quality full range music and HT with rich, deep musical base (not loud or pounding) in our limited space

I have have a suggestion that might fit your requirements and solve the electronics problem. But it is kind of radical and please don't get offended. I'm all about the best bang for the buck and max return of investment.

If you were to sell the Casablanca II, Rotel and maybe all or some amplifiers you have and replace it with something smaller that would do the same job? Depending on the power requirements of the speakers you have and are going to build.
Using another brand of room correction and making the whole system sleek and unobtrusive, scoring points with your wife?
Putting money towards the best speakers you can build?

Have a look at this "little" monster: Denon x6700h
Denon AVR-X6700H AVR Review (Updated)

The Denon uses the Audyssey Room EQ
Tested here: Audyssey Room EQ Review

The Anthem AVM60 seems to be a very good choice too, but I would always prioritize the speakers if you have enough power and sound quality in the rest of the gear.

Finally: Welcome to ASR!
I hope you enjoy your stay here.