Building an Active Main?

Randyman... · Post by **Randyman...** » Mon Aug 25, 2003 7:50 am

Hello all,

I am fairly new to this forum, and I must say there appears to be some serious knowledge here. Forgive me if I ramble...

I have always been into building project speakers since I was a kid. I mainly do subs (car and home audio), but now I am getting the bug to try and build some actively tri-amped 3-way mains for studio monitoring.

My home studio is currently a bedroom, but I am planning on buying a house in the next year, and I will make a 3 room studio and good sized control room out of it. I can't afford some of the "Mains" I would like, but I do have some very good amplification (6 channels worth), and I would like to experiment with making my own mains. By the time I get an OK sounding speaker set-up, hopefully my studio will be ready for them!

I have a pair of Mackie HR-824's (I know, I know) that I will compliment with some smaller woofered near-feilds (Dynaudio or Glenelec) as well, but I am used to having it loud when I need it, hence the need for hi-volume full bandwidth mains. Oh yeah, I am also a drummer

Anyway, if anyone has some good starting points for driver compatibility, and active crossover selection (I am thinking the DBX 260 or DBX Driverack - or even Sweetwater's modified Driverack for Studio) for pre-amp processing, I will be "all ears"

.

PS - The amps are some high end Sony ES amps from the late 90's - I have quite an arsenal with Two TA-N77ES (200WPC 8Ohms, 275WPC 4Ohms, 550W mono), One TA-N80ES (200WPC 8Ohms, 280WPC 4 Ohms), and Two TA-N55ES (110WPC 8Ohms, 150WPC 4Ohms). Yes, these are home audio amps, but they have crazy low THD, low noise floor, and power supplies to make even a Bryston look twice. Probably over $3500 in amps alone. I want to put them to good use.

I was planning on using the Two TA-N77ES in Bridge mono (1 left, 1 right) for the woofers (575 watts ea), and the TA-N80 on the midrange (200WPC), and a TA-N55 on Tweeters (110 WPC).

I want a 12" or 15" woofer that will reach fairly low (in the 30's), and a slightly "Bright" tilt as I have tinnitus.

I have been engineering on a semi-pro level for about 10 years, and I have been into audio engineering for over 15 years. I have a little "pro" studio experience with a set of Tannoy System 215's and 800a's, but my large format "Main" monitor forte is very limited, so I really can't say "I want it to sound like the large JBL's, or the Glenelec Mains"...

I will eventually soffit mount them if that has any bearing.

I know this is all subjective and many variables are involved, so thanks for any "experienced" input...

Later

barefoot · Post by **barefoot** » Tue Aug 26, 2003 9:06 am

Randy,

Wow, this is an ambitious endeavor.

What's your budget?

I wasn't familiar with the DriveRack. I looked at the application guide, but I don't think this will do the job. It doesn't appear to have the capability of cascading crossover filters with differing corner frequencies and Q's. The White ParaMedic or the Rane Multiprocessor might have the capability of cascading crossover filters, but I'm not 100% certain. Even so, they only allow the selection of a few fixed filter alignments (Bessel, L-R, Butterworth). This might be workable, but really you want to have the ability to input a specific filter Q.

How are your skills at following schematics and building analog circuits?

Thomas

Randyman... · Post by **Randyman...** » Tue Aug 26, 2003 10:25 am

Yeah, I thought it would be a bit more than I might want to bite into...

My budget will be fluctuating, and I had planned on trying a few different driver configurations without killing my wallet. It is more just for the self-satisfaction than trying to build something "better" than some Glenelecs, or what have you.

My budget - I was thinking around $500-$1000 on a processor, and roughly another $500-$1000 on drivers.

My schematic skills are far from adequate, but I am fairly sure I could make sense of a crossover circuit and a power supply. I have not built any complex circuits, but why not learn now? I need to, and this is a perfect excuse (for my own benefit)!

I would also assume to build an "Ideal" monitor, you need a good idea of the room they are to be placed in. This is still up in the air, so I really have no idea - other than I want to have a medium sized symmetrical control room with good relative dimensions.

I have strayed away from doing the full-range speakers with crossovers due to not having software for this. Al I have access to is the L/C reference values for resistive loads for 6 and 12 dB filters - no good - I know. I figured the active route would be somewhat easier, but I guess it is still a very tedious process needing appropriate testing gear to integrate the drivers together.

Speaking of the DBX Driverack, could the parametric EQ's be used in conjunction with the crossover to help come up with some asymmetrical slopes (at least in the higher-amplitude relative overlap frequencies)? I think each output has a dedicated parametric EQ.

Well, any more suggestions based on my ever-so-vague scenario?

Thanks for sharing your knowledge with us mere mortals!

barefoot · Post by **barefoot** » Wed Aug 27, 2003 5:53 am

Randy,

This is very doable within your budget. And if you choose drivers from certain manufacturers you can get pretty good results using just published data (i.e. the published data is very reliable so you can get away with not actually measuring the drivers yourself). I use LEAP 5 to design my speakers. It's the most powerful loudspeaker engineering software available, and it also provides a large database of drivers. I'd be happy to help you with the design as long as we publish everything here as a DIY project.

Thomas