Advice needed to build new 3 way active system

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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.
 
Dont forget to budget for some means of 6 channel volume control and you might want to get the input and outputs modified at some stage.

I think I didn't understood your point. Do you mean that I need to control the 6 channel volume after the crossover? My idea is to get the signal from the pre-amplifier (2 ch) send it to the crossover and then to those 3 amplifiers. One for the low freq, one for mid and the other for highs. This way I can adjust sensitivity differences between drivers. If I want to bring the volume up, I will do it in the pre-amplifier? Do I need something else?

The crossover points aren't set yet, but might be something like 250 Hz (4rd) and 1800 (4rd).

Please comment.
 
You start losing resolution when you attenuate a digital signal, hence you don't want to use the Behringer as a primary volume control. You're not anyway, so this isn't a concern.

However I'm sure the same is true in reverse. The Behringer digitises the analogue signal coming into it and I'm sure you want to keep this unattenuated also for the same reason.

This being stickinsects recommendation to have a 6 way volume control to adjust the level after all the digital manipulation has taken place.
 
hence you don't want to use the Behringer as a primary volume control

you should fix it to don't use Behringer at all...:spin:

if you still wanna use a digital XO, the best way to control the overall volume is to control the input GAIN.
hence the signal coming from the source before the XO.
this can be done by using a small mixer.

neither if you are budget tight or not i would recommend using analog crossover.
since you don't need a compressor and EQ and you are not gonna use the system as PA.
analog XO are cheaper and the audio signal is not converted twice:nownow:
 
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you should fix it to don't use Behringer at all...:spin:

if you still wanna use a digital XO, the best way to control the overall volume is to control the input GAIN.
hence the signal coming from the source before the XO.
this can be done by using a small mixer.

neither if you are budget tight or not i would recommend using analog crossover.
since you don't need a compressor and EQ and you are not gonna use the system as PA.
analog XO are cheaper and the audio signal is not converted twice:nownow:

Yes, analog XO are cheaper, but they are also more limited, at least the models that I know. I think that I will need EQ. My budget is 2000€, for crossover, drivers, amplifiers, and enclouser.

And about the drivers choices? Any comments or observations?
 
I'm going to be using PGA2310 chips for 6 channel attenuation on my 3 way tri-amplified setup. That is in conjunction with analogue filters, but it's still good to keep the signal level through them constant and of moderate level I feel. There are alternative chips, like those by Wolfson (if still available?), the PGA's at least are easily daisy chained for multi-channel control 🙂
 
But it's still good to keep the signal level through them constant and of moderate level I feel.

That hasn't been my experience. Mine sound great with small signals too. Of course attenuating the signal coming out of the active crossover, rather then before it, does offer in an extra level of protection for your drivers. As it is, if something goes wrong in the active crossover a huge and ugly signal could be amplified and blow up a driver. This hasn't happened to me yet and I've been using analogue active crossovers for almost 10 years.

And about the drivers choices? Any comments or observations?

The only thing I'd say is do you really need the MTM part? The only reason you'd want to add in the other mid is if you really need that extra 6dB, if you don't leave it out.
 
I think I need those extra 6db, each RS150 doesn't play very loud. Also using 2 drivers I can reduce the distortions numbers at normal listening levels.

Well, I guess is time to start design the loudspeakers enclosures. When it's done I will post it here.

Feel free to post more comments and suggestions.

Thanks.
 
I think I need those extra 6db, each RS150 doesn't play very loud. Also using 2 drivers I can reduce the distortions numbers at normal listening levels.

Thanks.

I'll start from the beginning.

If you've already got a nice sub and are planning on using it, you shouldn't need those three bass drivers at all, two will do fine and are most certainly better then using one.

I'd recommend you mount them push pull - both drivers mounted on the front of the cabinet, one above the other. Except one driver fires into the cabinet and one fires out. This approach cancels out some forms of distortion and is appreciable when in practice.

With regards to the bass to mid crossover I'd want to crossover reasonably high, say 400hz. It seems the RS270 would do decently at 400hz, but would need a steep crossover to sound it's best. This would nicely reduce the load the midrange has to handle, one of the reasons for doing a three way in the first place.

One of the other reasons to do a three way, is it allows you to use smaller diameter drivers in the mid range, letting you crossover higher whilst maintaining a nice power response. Maybe consider using the Zaph Audio ZA14W for the mids.

http://www.madisound.com/catalog/product_info.php?products_id=8643

This driver is brand spanking new and measures like a champ, rivalling the SEAS W15CY001 in performance, whilst offering better specs for use as a mid.

Crossover the tweeter as high as driver C-C spacing, or the harmonics of the midranges resonance peak allows.

Don't forget to compensate for bafflestep - this means altering both the midrange and bass driver crossovers.

If you're going sealed you could decrease the bass drivers box volume to create a higher Q alignment, so that it peaks a little. I'd guess you'd get some peaking around 40-80 hz perhaps. This in itself isn't great, but you can use the Linkwitz Transform circuit to electrically manipulate the driver to bring its response back to a Q = 0.5 for example. The peaking is equalised away and as a result you need less power to drive the bass driver around where the peaking used to be - then the sub takes over. Without a sub doing this wouldn't make any sense at all, unless you really needed to save space.

Finally, time align the tweeter.

The Behringer should allow you to do all of this, and better yet allow you to try loads of different xover points/slopes at the touch of a button. Just don't forget to include all the basics and you'll do fine.
 
you don't want to adjust volume going into the DCX.... think of it as your CD player, with the DAC to analog output of the DCX being your preamp and then feeding your amp. The DCX does not have the cleanest input in the world and in order to maximize signal to noise ratio you want either a digital signal going into the DCX or an analog signal set as hot as possible without overloading the inputs. If doing the latter, now that the DCX has done the analog to digital conversion, you use the digital domain to provide eq, crossover slopes and then whatever adjustments the DCX offers to provide the SPL matching between low, mid and high outputs of the DCX (this is all based on reading through most threads here and other places, I do not own a DCX or have good working knowledge of it, but I do know these basic concepts....), and then it all goes to your power amps and then your speaker drivers. So now that you have everything humming along at an ideal gain setting for the DCX and for each amp/speaker driver... how do you control the volume overall as a group, like you would with a traditional all analog set up of going CD player to Preamp to PowerAmp? Well after the output of each DAC in the DCX but before the input of your power amp, you want to gang it all up together and provide some analog volume control. Search this forum and others for six way volume control options for the DCX2496. Now you can skip all this to start with and simply use the DCX2496 as I believe it offers to control all the outputs via a single gang controller in the digital domain, but when you use the digital domain to lower volume, you are then feeding the DACs a lower resolution signal and the overall quality will be less than ideal, but if it were me I would try it first and then decide if I want the added complexity/expense of working out a six way analog volume control added on to the analog outputs of the DCX. Hope this helps.
 
Hi 5th element. Thanks for your advices.
I'm going to use only 2 bass drivers. Also using 3 would mean that a huge box is required. But you know WAF in the very low side. I have been thinking in the crossover points, and maybe I will set it between 300 and 400 Hz. I will try a few points and then decide wich one is the best. This is one of the good things about using digital crossovers like the DCX 🙂

I have been also looking at that new driver from Zaph. I realy like it. But that means that I must order it from USA and in Portugal I need to pay customs. That happened it my TC 2000 two years ago. I payed nearly as much for customs as I did payed to TC Sounds Inc. :S I'm buying the drivers from www.bmm-electronics.com.
And I will also take into consideration the aspects of bafflestep, eddge difraction, C-C spacing, bracing, damping, etc.

Thank you for your input.
 
Hi Greggo. I want to thank you also for your input.
You made a very important point that I will take into account also, and I will do it just like you said. First using only the DCX and adding the volume control latter.

I'm putting all the information I have got, and I'm starting to design the loudspeaker layout. Also I'm making some simulations to see what works better.

I will post the drawings when they are ready.

Until then, feel free to discuss more ideas and make suggestions.

Almost forgot, does anyone knows if I can get those Zaph drivers in europe?
 
But you know WAF in the very low side.

Maybe the Linkwitz Transform circuit would be useful to you for that? You can make the box small, say 60 litres and not have to worry too much about it.

I have been thinking in the crossover points, and maybe I will set it between 300 and 400 Hz. I will try a few points and then decide wich one is the best. This is one of the good things about using digital crossovers like the DCX.

Indeed, the flexibility is great and will most likely help greatly in achieving your goals.

I have been also looking at that new driver from Zaph. I realy like it. But that means that I must order it from USA and in Portugal I need to pay customs. That happened it my TC 2000 two years ago. I payed nearly as much for customs as I did payed to TC Sounds Inc. :S I'm buying the drivers from www.bmm-electronics.com.

Ah, I didn't notice that you were in Europe, I understand your pain😡 On the plus side I've used BMM once myself and was very impressed. The packaging was great and so was the delivery time.

Almost forgot, does anyone knows if I can get those Zaph drivers in europe?

You could contact BMM and ask them directly. Or you could go to http://www.htguide.com/forum/ Zaph posts there himself and you could ask directly if he's considering shipping to Europe. Some small thing in my mind tells me he did mention not wanting to distribute outside of the US, but then I could be wrong!

http://www.htguide.com/forum/showthread.php4?t=34369

Here is the current thread on his driver.
 
I have been also looking at that new driver from Zaph. I realy like it. But that means that I must order it from USA and in Portugal I need to pay customs. That happened it my TC 2000 two years ago. I payed nearly as much for customs as I did payed to TC Sounds Inc.
Do you need to pay duty on items mailed in? If not, ask here and someone might be willing to ship them to you as a favour. They're not very big or heavy so postage should be reasonable. A few people here and on other forums have done similar for me in the past.
 
Maybe the Linkwitz Transform circuit would be useful to you for that? You can make the box small, say 60 litres and not have to worry too much about it.
I'm able to make a box with 150 liters, not bad :spin:

Ah, I didn't notice that you were in Europe, I understand your pain😡 On the plus side I've used BMM once myself and was very impressed. The packaging was great and so was the delivery time.

Thank you for the info about the Zaph driver.
 
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