TOPIC:

I'm working on a dipole (open baffle) speaker using the miniDSP as a crossover and equalizer for the woofers. I will use the woofers from about 50-150hz. Above that my fullrange drivers (the Betsy 8"ers that I sell) will take over. They'll be crossed over passively, hopefully with just a single cap on the amplifier input in combination with the dipole rolloff.

The miniDSP is working wonderfully thus far! I'll followup with details on how I'm actually using it, but I need more measurements to really nail that down.

Paul
www.wildburroaudio.com

This is a big project, and it'll take some time to get it all done. At this point, I've constructed test baffles. I've also put the miniDSP in a box with pots, a power supply (I chose a linear wall wart type), an input buffer (a single unity gain op amp) and the buffer's power supply (a big regulated unit meant for Hagerman's Bugle phono stage that I pulled from the parts bin).

Paul
www.wildburroaudio.com

In the box.

Paul

I need to find a better way to measure the system response. I made the first plot by hand, and it was tedious! I'm working with Room EQ Wizard, but struggling on my old machine. If any of you know of free (or nearly free) software that will allow me to take measurements with a mic and my PC's internal sound card, let me know!

Paul

I'm also beginning what will be the tube preamp and amps for the fullrangers. They'll be 12B4 pre's and RH84 amplifiers crammed into the chassis of old Akai reel to reel chassis.

Paul
www.wildburroaudio.com

Brilliant Paul! It looks great and I wish we could listen to that nice Dipole setup you have!

While waiting for the Xover with bandpass (an upgrade to your existing plug-in which will provide LP&HP per channel) I'm wondering if using the PEQ as a filter would work for your application?

See below example where I just rolled off at 150Hz. I did it with 2 PEQ with low Q + 1 PEQ with higher Q @ rolloff frequency. Wouldn't this work? You could achieve higher roll off by combining a couple more PEQ... Anyway, just a hint to maybe wait on that plug-in (you should receive upgrade today/tomorrow) to see if that fits your needs?



Take care and keep sending pics of your progress!

Tony

Ps: Love the recycling of parts that this project involved! Nice creativity on your part on building your own DSP proc!

Interesting project Paul!

For measurement software I can recommend Sirp from Tolvan Data . You can download a free trial version to see if you like it. The full version is very affordable (35 €).

Cheers

/Mattias

Edit: Spelling

Thanks for the recommendation. I got Room EQ Wizard running last night, and it will be great fun. I believe it can suggest PEQ settings, which will be perfect for the miniDSP. My dog, wife, and the traffic were all too noisy to take meaningful measurements. My wife suggested I get up at 3 a.m. to try it. When I get a clean chart I'll put it up.

Paul

I get the impression that you have either a big house or a VERY understanding wife. In either case, congratulations man!

Cheers

/Mattias

lol... Agreeing with Mattias here. 3am sounds like quite late to play pink noise and run MLS measurements on these tall speakers! Hope you get the measurement right the first time because that may be the only chance you get!

Joke aside, glad that you got your test setup working! PEQ version will be released to the existing community members today.

Try this measurement software. It's made by a pro-designer, and its for free

www.diyaudio.com/forums/multi-way/144984...mpulse-response.html

I'm getting closer to getting the tube amps done. Still more troubleshooting. At least my PS seems to be on target. Then I'll have nothing to do but measure and adjust.

I do have a very understanding wife. These speakers aren't at all large by my standards. My most recent long-term pair was 12 cu ft (330L)each. That's about 14"x21" (.35 x .53 M) standing about 6 ft tall (taller than me). The downside of the OB's (from an aesthetic standpoint) is the need to have them out in the room. The big pipes were in the corners. Now, the sub (or subs) will probably be quite large. The TH-SPUD is 45"x48"x11" IIRC. I hasten to add that the miniDSP will be perfect for EQ'ing subs. But that is well in the future. Though I've got the drivers, I still need to build the box. And fix the chip amp that would power them.

I'll check out those software ideas. But, I do think Room EQ Wizard will be perfect so long as my laptop behaves and traffic isn't too noisy.

Paul
www.wildburroaudio.com

Great hearing that you're making good progress on your project Paul!

Keep it up!

I've been out of town for weeks, but I finally got the tube amp together. See pics and info here on DIYaudio . So, all of the big parts are done (both amps, miniDSP, speakers and measurement software). Over the next week I should have time to hook them together and set the system up.

more soon,

Paul
www.wildburroaudio.com

I'm up and running! First, here is the little amp. I used the chassis and iron from the amps that were originally part of an Akai M8 reel to reel. As you saw in an earlier post, I completely stripped them down. You can find a little info about my rework here . They are now sitting in part of their original box, albeit upside down! The 12B4 stage, with a cascaded mosfet CCS plate load and LED bias, is more than capable of driving the minidsp and woofer amp down to deep HT frequencies. The RH84 (SE partial feedback 12AT7 and EL84 amp) sounds absolutely spectacular. The bass is a little sloppy run fullrange, but here I am only using it down to 165hz! I included a (switchable in or out) pair of .03uf caps that sit in front of a 30Kohm level control, providing a first order rolloff. In combination with the baffle rolloff, I should be getting something akin to a second order slope.

Paul