[Zeverin]

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.

 

[Zeverin]

I will try to answer everyone, not without to say Thanks to the comments already posted.

First the choice on the RS180. In fact the RS150 was my first choice because of the ability to reach a higher freq. But some DIYers were saying that the RS180 is a better choice, the RS150 has also some nasty picks that I should be able to deal with. I will look for more freq. response graphics. But now that I have other opinions I might choose the RS150 .

For the XO points I'm thinking in something like this: 250 Hz (4th order) and 2300 Hz (4th order also) for the RS150. For the RS180 I was thinking in 2000 Hz. Want do you think about this choices? Can I push the RS150 to the 2500Hz region?


Using 3 270 is a too low impendance, I'm aware of that. The size of the enclousure is a real problem, not for me, but for my wife. 6 cubic feet sealed is my size limit, so that sets "only" 2 RS270 .

I know that for the tweeters (and also for the midrange) I don't need all the power from one A500, but I thought that would be better to use only one amplifier model. But maybe a could use a diferent one that matches the drivers specifications better. Do you have some sugestions? Please, only amplifiers with passive cooling.

Now the driver that JCD recommended. In fact I don't know that driver. But as I'm living in Portugal bying from USA means that I must pay customs. For my TC2000 I had payed nearly as much for customs as I did for TC Sounds Inc. The Dayton drivers I'm buying from bmm-electronics.com
Also, using a 12" driver means that the enclouser front baffle must be very large, WAF comes into play again.
More recomendations?

Thank you all.

 

[Zeverin]

I was missing the better off-axis response of the RS150. Thanks for reminding me of that The good thing here is that I can try different crossover regions Definitely 2500 Hz is too high, I will try 2100 just like you posted, and if I'm not happy with that I can always make some adjustments.

 

[Zeverin]

JCD: I just know a few online stores in Europe that have competitive prices. Another problem is to find reviews of the available drivers. Most reviews I can get refer to drivers manufactured in USA. My range of choices is very limited right now if I want drivers with good value without ordering from USA.
At some point I was thinking in the Lambda drivers from Acoustic Elegance. But they cost 245$ each plus shipping PLUS customs :foottap: I know they are great, by the price is very high. My budget is 2000€, including drivers, amplifiers, crossover, and enclosure.

 

[Zeverin]

Hi

Funny, I just joined this forum to get ideas on a 3-way system, and this project is a great start.

Have you considered to have three 8" woofers rather than 2 10"? Making speaker more deep and less wide should have better WAF

Hi. And welcome. This is a great forum. You I will find it very helpful.

Answering your question, yes I did, and agree that would have a better WAF. But the problem of impedance is still there. The only solution would consist in using one amplifier per driver. The cost of such thing is very high. I think that 3 drivers stacked vertical will need some compensation/attenuation because the floor resonances. I have seen designs using 4 8" drivers in a WWMTMWW configuration. With this configuration the impedance problem is solved, but my wife dislike those tall speakers.

More ideas are welcome.

 

[Zeverin]

Let me tell you my plans, perhaps you can use something here. Each speaker consists of:

1) separate box with 2 Peerless 830667 (8" subs)
2) separate box with Scan Speak 15W8530K00 and Vifa XT25 (Zaph's ZD5)

Crossed around 250Hz. Having separate boxes and running them active will allow me to mix and match later on.

Each box has own amp, so active W and active MT (MT has internal passive crossover)

All driven with DIY LM3886 amps.

What is the cost of that system?

 

[Zeverin]

I'd suggest you do a passive 2-way for the top and then go active with a bottom driver.

1 Your wasting amp on the tweeter and upper-midrange driver.
2 There are a lot of issues your are gonna have trying to actively cross the tweeter and upper-midrange driver.

I know that I'm wasting amp on the tweeter and upper-midrange driver. I'm still trying to find a cheaper amplifier with good sound quality and adequate power.
What are the advantages going with a passive 2 way just like you said, aside cost?

Do you think that is not possible to achieve a good integration between the tweeter and the midrange using this crossover? Can you be more specific in those issues? A little more info in my speaker configuration. The tweeter and mid drivers wont be centered to reduce baffle diffraction.

The A500 has a known defect with a distorted note at around 1000hz I believe. This has been shown in one case to be caused by being placed on another warm device. I do suggest you give them some breating room in your rack as such. I'd also propose you look into the EP2500 amp instead. The versatility and limitless power of these amps will do the trick with no concerns for defects.

Whichever amplifier I choose I will give them enough breathing room. Thanks for reminding that. I already have a EP2500 to driver my subwoofer. For this purpose I think the EP2500 is too much, and will raise the system cost, and I would like to stay with passive cooling.

 

[Zeverin]

This is getting interesting.
I want to think the sugestions already made.

lsiberian in fact I have readed those informations about bi-amping. But sometimes I miss some points.

I'm just going to discuss the disavantages.
1- If I go the bi-amp way, I would save money from one amplifier (aprox. 200 €). Great. But, I will need to spend on the passive crossovers. Maybe 80 € for both. That saves me 120 €. Also I will be loosing 2 outputs on the DCX, right?
I agree that 120€ is a considerable amount of money, with that I can almost build the rear speakers for a 5.1 system. But also look at this, I'm young, and certanly I will want to do more teaking and some upgrades in the future, going tri-amp (or 3 way fully active) I'm not going to loose the money spent on the passive crossovers. But I'm still considering any reasonable option.

2 - I completly agree that "one amplifier with twice the power versus two amps of half the power biamped is less likely to clip"

3 and 4 - I make JCD my words.

JCD by your comments I assume that you encourage the 3 way full acive, right?

Please, lsiberian and JCD (and others), don't be affraid to discuss more issues, better now then later when money is spent.

 

[Zeverin]

Hi. I'm short on time right now, but lsiberian and JCD are exposing very valid and wise arguments.

You know what? I will follow the 3-way aproach, BUT, not without trying the use of a passive crossover, just to learn a bit more, and see by myself the diferences both in sound and work involved, and also the results :nerd:.

I have built a few subwoofers, and also passive (2 way and 3 way) crossovers. Also in the last years I have been reading alot about loudspeakers design and construction. I know this is going to be hard, but I belive that I'm skilled enough to acomplish this project, even if it takes some time. This is a small beast I want to build. The enclouse shape will also represent one challenge by itself :coocoo:.

Latter I will comment some of yours arguments.

I think lsiberian makes some good arguments, and I certainly don't want you to ignore his advice/suggestions or think that I'm trying to portray him in any way negative

Of course not, and neither I, he is being very helpfull. Thank you. :bigsmile:

 

[Zeverin]

I posed this question to someone I know that has the technical backround to address this point -- his contention is that a 200 watt with a full range signal is more likely to clip than two 100 watt amps with an active crossover between them. There is a thread someplace on the web that this arguement has been addressed -- if I can find it, I'll post a link. I think lsiberian addresses the issues in most real world examples by actively crossing the <250hz signals, but I really don't think this is going to be an issue if you've got ~50 watts for the tweet and ~80 watts for the mid. , the tweet probably can't even handle a sustained 50watts.. but I digress.

Are you refering to this: http://sound.westhost.com/bi-amp.htm see point 1.4 Actual vs Effective Power ?

 

[Zeverin]

1. Not sure how you are getting that a passive crossover is going to cost you 80 euros. Most can be assembled for far less.

Maybe it is too much. 60 euros is more reasonable for the 2 crossovers.

2.You can still manipulate the entire sound of your system with the DCX. You'd be giving yourself the ability to hook up your subs to the DCX. Meaning you could have a 4-way setup with the subs fully eqed.

This is a good solution to fully use the DCX flexibility.

3. Fully active is just as time consuming as making a 2-way upper module filter. I"m not talking about passive between your bottom driver and the top. Only between the tweeter and the midrange.

You are right, it still takes a lot of time. But with one active system like this you can try diferent crossovers point and slopes and see what works best in the room :innocent:

4. Don't forget that XLR cables aren't cheap either.

Yes, unfortunately very true :thumbsdown:

But I would encourage to at least give the passive crossover a go. If anything it will be a valuable learning experience.

A very valuable experience. I will follow the 3 way fully active path, but I will take into consideration your advice and try it also, just to learn a bit more.

In a few days I will have the cabinets modeling completed, then I will share you you.

 

[Zeverin]

Hi mayhem13. Thank you for the suggestions. Do you know any online stores that sell those drivers? Also can you point me some cool projects using drivers of the listed brands?
I really like the PRO stuff, but the looks!!!!:wits-end: I know that you can't have everything, but I look forward for some cool projects with PRO drivers.

 

[Zeverin]

Hi. Sorry for the late reply. I had contacted a distributor in Portugal of 18sound, and asked for the price of the 6ND430 driver. They are charging 75 €uros, that is the price of two RS150. Do you think it's worth it?

In a few days I will be posting the 3D model of the enclosures

 

[Zeverin]

Well, I had been looking over and over the measures taken by Zaphaudio. And in fact the performance of the 6ND430 is trully impressive. This means that I'm going to spend the double in the midrange drivers, but the added performance (distortion and dynamics) is worth it. Thank you mayhem13 for those great advices. The only problem now, is WAF. My wife dislike the looks of the 6ND430, in fact I don't like it also, but that's not the important factor here. Soo I must convince her, wish me luck.
I havent found a replacement for the RS270, and I'm open to new suggestions. But only 10" drivers please. I like the 10W400 also from eighteensound, but I'm lacking of information about their performance. Any recomendations or information about the 10W400? I can get it for 84 €, rougly the same price of the RS270.

 

[Zeverin]

Hi bdp. Thank's for the suggestion. I'm afraid that I don't agree completely with you. If I lower the sensitivity of the woofers I need to use more power, more power equals more expensive amplifier (perhaps noisy fan cooling), and the distortion number can raise quicker (maybe, maybe not), and they "only" need to handle frequencies above 60 Hz, below 60Hz my TC 2000 15" is going to take care. I also like the idea of using a bigger surface to move gently the air, than a smaller one moving the air in a more violent manner. Those this assumption makes any sense?

 

[Zeverin]

I want to achieve 110 db (continuous) at 2 meters listening position from 30 Hz to 20KHz. The TC 2K can assure that extension down to 30 Hz (powered by one EP2500). The "weakest" component here is the tweeter, but with a sensitivity of 93 db, I think that is enough for me. I'm going to use 3 behringer A500. Power availability will be something like this: 200 W for woofers (2 RS270 8ohms in parallel), 200 W for mids (2 6ND430 8ohms in parallel), 120 W for the tweeter (SBAcoustics SB29 8ohms), each channel, all RMS values.

 

[Zeverin]

Here you can see the last draft I have, with the RS150 as mid drivers, not updated yet. Some changes are going to take place, than I will update the 3D model again, including other views.
I hope that you like.
I'm aware of diffraction problems with a so width baffle.

Please make some comments.

3D modeling credits to Suriv

 

[Zeverin]

Adding a rear firing tweeter could be challenging but it has the potential to help ease the strain on your current weak link tweeter. IN theory you would have nearly twice the output.

I will leave that for future teaking, but thank you for the suggestion :rubeyes:

Adding a rear firing tweeter could be challenging but it has the potential to help ease the strain on your current weak link tweeter. IN theory you would have nearly twice the output.

Good luck getting the bass to sound right. It seems like you have to go sealed, due to the large airspace requirements of the rs270. This will hamper response between 30-60hz. OTOH, you will experience boundary reinforcement from the woofers that are close to the floor. I am not aware of any current tool that can simulate this boundary effect.

You are right, I'm shooting for sealed encloures with 150 litres. :T

 

[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.

 

[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.