[Zeverin]

First, thank you all for your comments.

Any particular reason you want to go 3-way and not 2-way?

My goal is to create a speaker with low distortion playback and good dynamics. I know that this can also be achieved with 2 way, but I feel more confident in a 3-way. Maybe a misconception . As some of you might know the TC 2K isn't great above 80 Hz, so this speaker must play loud and clean down to 60 Hz (yes 60, not 80 Hz, I prefer to cross the sub at 60 HZ).:nerd:

If you're gonna go that route, then you might consider going with 3x Crown XTi:
http://www.crownaudio.com/amp_htm/xti.htm
It has a DSP built into the amplifier. They can easily be found for $300 each on the used/b-stock market.

I believe that is a good solution, but I'm afraid I can't get those in Europe, and I don't want to order outside Europe, because of customs. But I will keep my eyes opened. :blink:

Have you thought about building some horns?

Yes I did. But I don't have enough knowledge to do that. Also I must keep WAF on the high side.
Maybe after this I can jump into the horns field, I'm very interested indeed.

You can always wire the woofer in series if you're worried about low impedance. When using an active crossover, you don't take any efficiency hit to balance the drivers with each other.

Yes I can. But that way I'm not extracting all power from the amplifier, and in this particular case, instead of 220 W I would have something around 100 W. Did I miss something?:innocent:

Keep in mind that 110dB continuous A-weighted still involves 20dB of crest factor in the music. If you don't want any clipping or compression, then your system will need to be capable of 130dB peaks (yikes).

A 93dB tweeter would need a 5000W peak power handling to achieve that (not gonna happen).

Btw, 110dB continuous is rock concert loud...is that really how loud you plan on listening?

I think that I didn't make myself clear here, my mistake, sorry. When I meant 110 db continuous, was a system capable of maintain that playback level for a few minutes continuously. Here I'm taking into account thermal limits and available power in RMS values, not some peak values. This way you should "read" 90db continuous A-weighted (with 20 db headroom for crest factor in music). I think it makes more sense now.

 

[DrWho]

Yes I can. But that way I'm not extracting all power from the amplifier, and in this particular case, instead of 220 W I would have something around 100 W. Did I miss something?:innocent:

You don't lose any SPL since doubling up on drivers halves the acoustic space that each is firing into. What you gain is extra headroom in the drivers.

You're just shifting the impedance matching around. Essentially, the amplifier is doing half the power but the drivers are doing effectively twice the power so it ends up a wash.

Have you done any thinking about polar response? Dual 6" drivers can't get any closer than 12" center-to-center which is going to start beaming above 1kHz. The beaming will create on-axis boost, but reduce the amount of output in the off-axis. You're gonna end up in a compromise between dialing in the direct sound that follows precedence effects against dialing in the off-axis "reverberation" of the room. The ideal world would be one where the off-axis energy and on-axis energy have the same tonal balance (flat power response).

The B&W 802D seems like a very similar speaker to what it seems like you're aiming for and it very closely approximates a flat power response:
http://www.bowers-wilkins.com/display.aspx?infid=1157&terid=1305&sc=hf
Notice the single 6" midrange. There's no need to go all crazy style with the woodworking, but I would recommend a similar baffle arrangement.

If nothing else, I would try to find ways of making the polar response between the various sections try to line up at the xover frequencies. The difficult part about direct radiators is they tend to be very wide at the low end of their response and very narrow at the top end of the response. This is where MTM arrangements can be beneficial, but they need to be carefully thought out with respect to the xover frequencies you plan to implement.

 

[brianpowers27]

If you ask me...

You may need the dual midwoofers (rs150?) to keep the sensitivity high enough to get the job done. You could also use the RS125 and perhaps get a cleaner top end out of the mid.

The only real need for 2 tweeters is sensitivity matching. I imagine that 2 mids along with 2 woofers will be too sensitive for a single seas tweeter as posted. This combination hasn't really been done before(at least that I know of) but that doesn't mean that it is bad. I imagine that the reason it hasn't been done before is because the sensitivty of the woofers will likely outpower all but the most sensitive tweeters on the market. You would need about a 95db tweeter to match sensitivity.

+1 on the power response comments. I would suggest considering tese xo points.

woof-mid 400hz lr2
Mid tweet 2000hz bw3.


This will give you a very smooth power response and provide adequate protection for the tweeter and limit mid excursion.

 

[evilskillit]

I would just like to chime in and point out that there are already several 3-way designs that are very similar.

The Dayton RSTMWW uses a Seas Tweeter, Dayton RS150 for mids and RS225 for bass.
The Kahnspire uses the same mids and woofers with the Dayton Reference Tweeter.

I'm interested in building a RSTMWW myself but if I was thinking of designing something from the ground up I would probably use a "better" midrange driver like the new Zaph 5" driver, or the 4" titanium tang band or something. Or maybe even the Dayton dome mid-range like Zaph uses in the ZDT3.5

 

[Zeverin]

Hi again, finally got some time to came here. The next two months will be also very busy.

Have you done any thinking about polar response? Dual 6" drivers can't get any closer than 12" center-to-center which is going to start beaming above 1kHz.

Mike, I really appreciate your comments, but I can't agree with you in this one. The c-t-c distance is not only dependent in the midwoofers size, you need to take into account the size of the tweeter, in this case it's not bigger than 4", if we add 0.5" for drivers spacing, the c-t-c for this particular combination of drivers is around 11", but with smaller tweeters we can achive smaller c-t-c. I have been thinking about the polar response and comb filtering issues, but I'm willing to try this WWMTM configuration, and than share the results with you. Also, I think that I can reduce the ctc distance if I can cut the tweeter flange. what do you think? That would allow a higher crossover point by a few Hz (50~100Hz flange cut dependent), reducing strain in the tweeter. I think that a ctc distance near 10" is possible.

 

[Zeverin]

I will be no longer using the Dayton RS150, my current choice is the 18Sound 6ND430 :neener:

 

[Zeverin]

Construction thread here:

http://www.hometheatershack.com/for...y-active-loudspeakers-construction-diary.html

 

[WmAx]

EDIT: I apologize for my response. I did not notice that you had already purchased drivers and started the project. I will leave the reply in tact for possible future references, however.

Perhaps you should consider using high grade professional audio mid-range that is specifically designed for extreme SPL and has very high sensitivity. For the woofers, please keep in mind that only the higher quality drivers have low power compression. If feasible for space, the Audio Elegance AV 15" driver has higher sensitivity than most comparable drivers and overall good power compression and motor linearity characteristics for a bargain of a price. One of these in each cabinet will be very good. Also, the drivers can play to much higher frequency than most 15" subwoofers due to this being a specific target objective when they were engineered. You could cross at 200-250hz, no problem, to blend with a high grade 6-7" pro cone driver. Just be sure to use very high levels of high grade acoustic damping in the subwoofer volume, such as Owens-Corning 703 or 705 or comparable, at very thick amounts(for example, minimum 6" on rear of cabinet and bottom of cabinet, 4" on other surfaces. This will ensure a broad band capability with minimum standing wave resonances within the large volume. Standard acosutic damping materials common for speaker use are not sufficient for this particular application.

As for the tweeter; I have no idea what kind of HF polar response properties you desire. But if the vertical limited axial response is okay with you, Fountek has a reasonably priced professional ribbon tweeter with extreme high sensitivity and broad bandwidth capability, allowing for very high SPL capabilities that you desire, but yet retaining the characteristics of SQ you desire. It's horizontal directionality is not limited; only vertical. Unless you intend to listen critically while walking around the room, this will not be a real problem for normal seated listening within an estimated 8-12" vertical window target.

Chris

 

[GranteedEV]

Hi.
I'm planning my new system. I want to build a 3 way active system (front speakers).
My current ideia is to use the ULTRADRIVE PRO DCX2496 as the crossover. The amplifiers will be 3 A500 also from behringer (one for each channel).
The drivers configuration will be MTMWW. The tweeter is the Seas 27TBFC/G, the midwoofers Dayton RS180 and the woofers RS270. The box will be sealed because I want the most clean and "fast" sound I can achive. The midwoofers and woofers will be wired in parallel (4 ohm load on the amplifier). I would like to add a third woofer (MTMWWW), but that would have a dificult impedance for the amplifier. Why another 3rd woofer? Because of the added dinamics and lower distortion numbers at a given listening level. Any solutions?
I currently have a TC 2000 15" subwoofer in a sealed box with 110 L crossed over at 60Hz.

Please post your comment and sugestions. Keep in mind that budget is a constraint.
Thanks in advance.

here's a speaker that fits what you're trying to do; high end mids with phase plugs and a scanspeak 9500 tweeter, very high end aluminum drivers. The mids and woofers on that are proprietary though made by status acoustics.

http://www.rbhsound.com/product_detail.php?id=8300-SE/R

I'd contact them and ask them how what the impedance for the drivers / wiring they used to get it to work out.

 

[Theresa]

Check out the miniDSP "in a box" from DSP4YOU. They're in Hong Kong so its about $40 shipping but they are tiny units using USB (use a cell phone charger for powering after programming) for power and PROGRAMMING. You can change crossover frequency, delay, phase and has many parametric equalizers all programmed with your computer. Super easy to set up. From what I heard they were started by three engineers seeking to provide an inexpensive DSP crossover with much flexibility. The unit that's in a box rather than just a circuit board is about $160 after shipping to the US. I have two of them, one for the main channels and another for the sub and center.

 

[GranteedEV]

I'd consider this:
http://www.bcspeakers.com/product.php?id=175

 

[Zeverin]

Thanks Chris.

In fact I already had the mids and the tweeters, still waiting for the Dayton RS270 woofers.

 

[Zeverin]

Check out the miniDSP "in a box" from DSP4YOU. They're in Hong Kong so its about $40 shipping but they are tiny units using USB (use a cell phone charger for powering after programming) for power and PROGRAMMING. You can change crossover frequency, delay, phase and has many parametric equalizers all programmed with your computer. Super easy to set up. From what I heard they were started by three engineers seeking to provide an inexpensive DSP crossover with much flexibility. The unit that's in a box rather than just a circuit board is about $160 after shipping to the US. I have two of them, one for the main channels and another for the sub and center.

Hi Theresa.

A few months ago I was looking at the miniDSp you indicated. But I don't think that is a good option. Those units only support 2 inputs and 4 outputs. Definitely not enough for a 3 way, soo I would need to buy 2 units, costing 190$, plus shipping, plus customs. I can get the BEHRINGER DCX2496 for 265 € from a local store. I think that I'm going to choose the DCX2496. But thanks anyway for the suggestion.

 

[Zeverin]

I'd consider this:
http://www.bcspeakers.com/product.php?id=175

Sorry, it's too late. Already started the construction. Please refer to: http://www.hometheatershack.com/forums/diy-speakers/32955-jubilo-3-way-active-loudspeakers-construction-diary.html