DIY Speaker project

Calling out to any folks here who know their stuff about speakers, crossovers, etc.
I want to try some experiments over the summer using a pair of these drivers:

http://www.parts-express.com/pdf/290-409s.pdf
which I have, but they're still in the box at the moment.

It's a "full-range" 12 inch woofer with a wizzer - but its freq. responce is only good to about 8-10KHz
(the 7th harmonic of note F5 at 8 foot pitch) - so it really should be supplimented with a little dome tweeter.

The organ at Zion is going silent for the summer, so the first thing I'll try is to mount them in some 12" holes in the "infinite baffle" here: and see how they sound alone - unenclosed.


Then I think I'll try them in some really big PA enclosures I just happen to have. First alone, then in tandem with some 15" vintage CTS organ woofers.

Then, I plan to build 1.8 ft3 enclosures - per Eminence's recommendation and run them with a 1" dome tweeter crossed over at 6-8KHz.

Anybody had experience buying and/or building passive crossovers from Parts Express?

Hi Bob

I'd crossover much lower - at about 4khz. The impedance of your woofer is over 30 ohms at 8khz and crossing over at the lower frequency will keep the impedance under better control. Dome tweeters are typically good from about 2.5 - 3khz up.

There's some crossover info here: http://www.jaycar.com.au/images_uploaded/crossovr.pdf

And there's a freeware enclosure design software here: http://www.linearteam.dk/default.aspx?pageid=winisdpro

You can enter the Thiele/Small parameters and it will compute the response for any type of box.

Don
Oz.

Hi, Bob.

Other than the full-range drivers I'm using, I've gotten all my speaker parts from Parts Express. Highly recommended.

I agree with Don. You want to crossover lower than you suggested. I've been using BassBox Pro and Xover Pro to design my speakers, and while they're not free, they work well. The rising (and not very smooth) response of that driver above 700 Hz makes the crossover design a little tricky, so you'll want to use some kind of modeling tool (and pay attention to both amplitude and phase response).

Hi!

Those speakers look tough. Personally with the wizzer I'd put a tweeter on only with a simple capacitor as crossover. Keep It Simple is my motto and using the mechanical rolloff of the woofer with a tweeter running gently in as the frequency increases gives a nice, natural, smooth sound.

Nicely efficient if the specs are to be believed.

You might take out the dustcap and insert a phase plug.

Best wishes

David P

I have to agree with David at this point.

The whole purpose of buying/trying these particular woofers was to get as full-range as possible out of the primary driver.
If it weren't for the fact that I want to run 4 foot diapasons on these speakers as well as 8 foot, I'd probably pass on the tweeter altogether.

These drivers come very highly recommended on all the DIY speaker forums, particularily the single full-range driver niche.

The criteria is as clean (hi-fidelity) as possible, while still being powerful enough (200 plus watts) to be in the PA class, while still being affordable ($120 a pair).

The primary challege is the rise in dB in the 1000-2000 Hz range - which makes them good vocal PA drivers, but for our purposes, something is going to have to be done to compensate. Such as a cap ??, or simply using Hauptwerks voicing capabilities to make the best of them.

I have been doing alot of research on full range drivers as I believe they could give the most natural sound due to a lack of a crossover and being a point source.

My biggest concern about them is:

1. The rising upper end. There are other drivers out there that extend up to closer to 20khz but they all have a rising top end that can be compensated for with a Zobel network if one takes enough time to find the right values, or use Hauptwerk's voicing tool.

2. My bigger concern though is the uneven (jagged) response as the frequency rises. With pipes that can be voiced individually this isn't as much of a concern, although the harmonics will still be somewhat affected. The bigger concern are mixtures where one can only voice each note as the set of pipes playing as a whole.

Maybe I'm too concerned, but have also been researching 2 way speakers. I believe if the crossover frequency is high enough ~ 3K then the sound will be affected very little vs full range drivers where there is no crossover.

I also am very interested in using a bipolar arrangement. But this doubles the price of each speaker.

I was surprised to see these 12" drivers are sold on parts express. Looking at their full range driver page I've only seen up to an 8" driver. Actually the Pioneer one they show I've read some audiophile reviews on and they aren't too bad. But again I don't like the jagged upper end.

Eric

I should have been more clear from the start that I only plan to route 8 foot and 4 foot flues through these speakers.

The upper work - everything 2-2/3' and above - would be handled quite nicely by the following sets of speakers:
Behringer B2031P passive reference monitors
Bi-polar towers made up of Infinity Reference 6X9 coaxials - wired in pairs

The reeds will be routed to six matching Allen HC12 cabinets.

My hope is to minimize IM distortion of the pipe ranks at 8 and 4 foot pitch using cabinets with full-range 12" drivers. Specifically, the 8' and 4' flues in the Swell and Choir of the E.M. Skinner - which are typically heavy in the foundation to begin with. All the flues in the Great will be real pipes.

And remember, I need to fill an 80,000 ft3 space with sound. The 225 watt power handling seemed to be a good match for my Behringer A500 amplifiers. I have to voice every single pipe individually anyway.

So you see, there's more to the story and I have fairly specific needs.

Yes I thought of using smaller speakers/drivers for the higher pitched ranks. Are you using the B2031P's yet? I may try some of these but still wonder why they call them near field monitors when they apparently work well at a far distance. My home environment is nothing compared to your large building though.

Are the bipolar towers you're mentioning something you would build yourself?

Yes, the B2031P's are in play, but at the moment I'm routing most of the 8' reeds to them.
Choir/Solo: French Horn, Orchestral Oboe, Swell: Trumpet, Oboe D'Amore
They cannot handle the power necessary for the Great and Pedal Trombas, not to mention the Tuba Mirabilis.

As of now, Infinity 6X9's are mounted in the baffles (see photo), and I have to wire two of them together in series - 2 per channel. But I'm planning on building bi-polar tower enclosures for them, since the baffles are getting opened up and the sound opening expanded from 3-1/2' X 12' to 7-1/2' X 15' for the real pipework that will be in the organ chamber.

Just got home from one of my late night missions at the church. I successfully unmounted the 12" subwoofers, which have been offline for sometime now, and used those openings (see photo above) in the baffles to mount the Eminence Beta 12lta full-range woofers.

I hooked them up to one of the Behringer A500 Studio Reference amplifiers that was driving the Behringer B2031P's.
This 2 channel speaker group is running in modified stereo - samples loaded in mono with HW simulated stereo.

As an experiment I routed the 8' Diapason (Skinner Great 2nd Diapason), the 8' Harmonic Flute, Great Tromba, Swell Trumpet and Oboe D'Amore, and all the various Choir/Solo reeds: French Horn, Orchestral Oboe, and Tuba Mirabilis.

My initial 'ears only' observations without the aid of any measuring equipment:

The speakers are much more efficient than the Behringer B2031P's
The 8' Harmonic Flute has never sounded better
There was no noticable loss of upper harmonics - at least through the first four octaves.
The regulation seemed pretty even throughout except in the first octave (64-128 Hz fundamental) which was a tad softer.
The quality of the Eminence Beta 12lta over my old Conn Organ Speakers (15" CTS full-range woofers) was night and day (or I should day and night, respectively).

I will be making some comparison recordings using my R0DE NT1 microphones and KORG M1 recorder in the next few days. I plan to compare head to head the following speakers using 2-speaker groups.

Eminence Beta 12lta's
Allen HC12 organ speakers
Conn (CTS) 15" Organ speakers (bi-amped) with Bose 401s
Behringer B2031P's

I will be interested in your findings Bob. I purchased a set of the B2031P's the other day and had one night to play with them so far, until I tried to install 3.22 and now nothing is working. I've been using a set of older (80's) Koss 3 way full range hi fi speakers, and compared to them, the Behringer's sound much duller. Also the Behringer's are much less efficient even though they are specified at 89 db@ 1w, 1 meter. I find it hard to believe my Koss's are that much more efficient, so either they are, or the Behringer's are less efficient than specified.

I'm suspecting the duller sound can be improved with voicing but I think now I will try a pair of the highly efficient full range drivers to compare.

Here are the results of my test recordings. All recordings where made in the same session last night.
All recordings are of the same midi file (by James Pressler).
Only the 8' Open Diapason is drawn (Skinner Great 2nd Diapason)
With the exception of one file, all recordings were made using the same amplifier.
Equipment used: R0DE NT1 microphones -> Mogami Gold series cables -> BlueTube mic pre-amp -> Mogami Gold series cables -> KORG M1 field recorder.
Recordings were made at 24-bit, 96Khz - and then some post-production was done in Sony Sound Forge to make each file roughly the same amplitude (peak @ -6dB) and converted to CD quality 16-bit, 44.1KHz.
The following sets of (2) speakers were used:

Eminence Beta 12lta (8 ohms)
Behringer B2031P (8 ohms)
Eminence Beta 12lta and Behringer B2031P wired in parallel (4 ohms)
Allen HC12
and
The existing 'Mains' consisting of a 15" Conn (CTS) full-range woofer organ speaker and a Bose 401 array - Biamped

They are listed here in random order and not in the order I recorded them:
http://zionorgan.com/HWForumImages/test1_1644.wav
http://zionorgan.com/HWForumImages/test2_1644.wav
http://zionorgan.com/HWForumImages/test3_1644.wav
http://zionorgan.com/HWForumImages/test4_1644.wav
http://zionorgan.com/HWForumImages/test5_1644.wav

One thing I'm wondering about is you mention 8 ohms for the B2031P's. Mine are listed at 4 ohms and according to the specs that is the only option. The B2030P's are listed at 8 ohms though.

I tried to play the files but then realized I don't have a way to play the .wav files at this time.

OK I downloaded a free wav player and downloaded the files so I could easily switch between them. There is quite a difference between them with two of them sounding much more nasal. There definitely appears quite a quality / clarity difference between them. As they are random, how does one know which file goes with which speaker set?

Perhaps I made a bad assumption (it was late at night and I didn't even check). And that would mean I was showing the amp 2.66 ohms. That would explain why (I felt) I had to shut it down and let it cool a while after that particular test. And here I thought maybe I had some strands of wire touching or something...

Can you burn the wav files to an audio CD and listen to them on a good hi-fi ?
There's nothing there lower than 64Hz