I finally got my new prototype pair of compact rear horns finished today and am having fun testing them out. The low frequency resonances tuned to 24 and 25 Hz respectively. I've got 10 feet of horn folded up inside there and am using two 3-1/2 inch drivers full range and a piezo tweeter on a homemade lens. The bass is very smooth and firm, not boomy. I could use a bit more mid range punch though, but have room for a separate dedicated mid driver and I plan to purchase better drivers for these when I get a chance. I had to work with what I had laying around. They are very open and airy with excellent soundstage and very large sweet spot. They are built not to vibrate from MDF and weigh 65 lbs. each. They are 50-1/2 inches high and 7-3/4" wide.

Someone in the Toronto area with a stereo pair of 300B SET amps should come visit me for trials.

Rob

I'd love to check those out with my 45 SET. Actually, that is similar to a design I'm considering for audition. Its a folded horn but uses a single Fostex driver. Congrats again!

MikE

That is incredible bass extension your getting with those small drivers! Did you play around with a high pass on one of the full ranges to boost the mids? If so how did it effect the bass?

Ok how did you get 10ft of backloaded horn in there???? Are they folded like a transmission line or flared??? You must have a gradual flare rate. How deep are they? That must have made the cabinets fun!! Wow Great bass extension from them!!! Where are you crossed over to the piezo??? I have never tried them. The ones in the DQ-10 were awesome really nice and open sound.

Rob, Thatch,

I feel a bit guilty perhaps for teasing but in this case
I cannot discuss specifics of line shape beyond length and the obvious that it terminates in one rather large hole given the cabinet dimensions. No comment either about crossover techniques. Sorry. You are in effect asking me for future mortgage payments. This represents my hopes for a new chance at earning a living since I'm running out of options because of a devastating automobile crash injury.

The cabinets are slightly over a foot deep at the bottom with a slight pyramidical taper on the back to less deep at the top. I don't know what that is in metric. :)

On the other hand my recent very successful design for my full range giant front horns is an open book because I have no intention of marketing those.

Rob

Good luck on your new venture!

Rob2:)

Thanx Rob for understanding.

very nice looking speakers ya made Rob. I would love to someday have the oportunity to listen to them along with your amps too...maybe we'll cross paths someday at a DIY event...or something.

take care...and best of luck to ya! :beerchug:

rob, love the look of the speakers, i've always thought that for fast bass there is 2 options, big 15 or 18 inch drivers in a sealed or open baffle. Or the route your going, small drivers that are horn loaded. I've been thinking of using the tangband 3" or 4" for some t-line speakers but haven't got around to it yet.

I wish you all the luck in the world with your speakers, it would be nice to have some different opitions when buying bookshelf speakers, and the idea of horns is very exciting. Please let us know how the sound.


shibby
Allan

Originally posted by poorboy
rob, love the look of the speakers, i've always thought that for fast bass there is 2 options, big 15 or 18 inch drivers in a sealed or open baffle. Or the route your going, small drivers that are horn loaded. I've been thinking of using the tangband 3" or 4" for some t-line speakers but haven't got around to it yet.

I wish you all the luck in the world with your speakers, it would be nice to have some different opitions when buying bookshelf speakers, and the idea of horns is very exciting. Please let us know how the sound.


shibby
Allan

Shibby,

For fast bass you want a front loaded horn like the ones I made earlier this year. The bass wave and the higher frequency waves are all time aligned from such a design at the listener position. In the rear loaded cabinet the low frequencies that make it out of the bass horn have been travelling in other directions more or less perpendicular to the listener while the front radiation from the driver has been heading on the journey to the listener. When the bass finally exits the box and begins it's airborn journey the treble has probably reached the listener's ears. Fast bass it ain't.

I think the main advantage of a rear horn is to pull up the efficiency to the point that you can get useable bass from a tiny driver that can also reproduce a fuller spectrum. This makes single driver cabinets with quite good sound possible. A good design can also give a bass extension lower beyond the driver's Fres than a bass reflex design. I'm getting a full octave extension with my design currently. I am no where finished with my R&D BTW, but do not expect to get deeper bass, hopefully just more smooth, and more powerful. I intend to experiment with other drivers.

Those TangBang full range drivers sure look interesting to try. They very well could be great in a line array. Let us know if you try that.

Rob

Well I got a chance to put better drivers in my rear horns and they sure sound better. Ribbon tweeters, 4" full range Tang Band and a 6-1/2 inch Dayton woofer with an Fs of 33 Hz. I'm not zeroed in on a final production design yet though, but getting closer. In the meantime, these are now fairly good speakers. :)

Rob

Hello Rob

Very nice looking speakers. Bet they sound good. How do you like the Tang Band???

RobH

I must say I'm pretty impressed with this one. The build quality looks very good. It is the biggest, most expensive TB in the lineup of them at PartsExpress and is the only one with a cast frame. The motor is huge. With 3mm excursion it has the most travel of all of them as well. Frequency range 65-15000 Hz. It works very well all by itself as a full range and the doppler modulation or IM of the highs with a bass note is not nearly as bad as I would have expected. I tried singles and pairs full range by themselves and they were quite smooth. Qts is a nice low 0.35 so it is OK for putting in a horn. I think a line of this driver would be great in an array with a tweeter in the middle of the pack.

IMO these drivers are worth experimenting with. They are very affordable right now, but this may change as the world discovers them. I was quite surprised to get consecutive serial numbers 346 and 347 in the lot of four that I purchased to experiment with.

Rob

I like the look with the new drivers too. Understated high tech. I am sure as time goes on they are changing, the spiders loosening up a bit with play time which is very important for phasing with that ribbon tweeter.
A way to achieve better phasing I have heard and soon to try is to set the front of your ribbon( in my case it will be the diapragm in the middle of a Heil AMT-1) directly over the voice coil of your full range.
With your setup that will raise the SPL of the ribbon as it would essentially be in a horn. Whether or not you need to do this or how it would effect the efficiancy of your speaks in toto I have know idea.
Nice work!

Originally posted by Thatch_Ear
I like the look with the new drivers too. Understated high tech. I am sure as time goes on they are changing, the spiders loosening up a bit with play time which is very important for phasing with that ribbon tweeter.
A way to achieve better phasing I have heard and soon to try is to set the front of your ribbon( in my case it will be the diapragm in the middle of a Heil AMT-1) directly over the voice coil of your full range.
With your setup that will raise the SPL of the ribbon as it would essentially be in a horn. Whether or not you need to do this or how it would effect the efficiancy of your speaks in toto I have know idea.
Nice work!


Thatch,

Thanx for the compliment. I like the new look as well. The stone painted add-on baffle accomplished a doubling up of the 3/4" thickness of the baffle board as well which also created a sonic improvement at the same time as allowing driver relocation/changes without building an entirely new, and somewhat complicated enclosure each time. You should see some of the hole adapter rings I have made during trials! :) I have come up with another idea and must however make another set of 'boxes' to evaluate it. It is a pretty major re-think of the same theme and involves lengthening a portion of the horn path.

I considered 'sinking' the ribbon to achieve voice coil alignment but my cabinet design does not give me any allowance to do this inside. I would have to project the full-range and bass drivers instead.

I am very pleased with the realism and transparency I'm getting from the mids and highs currently. The present layout certainly works well, although it could possibly work even better taking into account what you suggest.

Please let us know how this affects your Heils if you try it more than one way and can hear a difference.

Rob