Suitable midrange cone, for bandpass mid in Unity horn.

Well, you may get your chance before too long! We'll be moving to Portland OR in August, so not too far away from you.

But my 'listening room' (a.k.a. 'basement') will have only 6.5foot ceilings, so acoustics may be less than stellar. I'm actually plotting a tall Synergy version that has narrow controlled vertical down to schroeder to (I hope) help with that. Will have to see how well the little tool shed I'll have there will do for doing horn piece cutting.

This time around I want to try to use DE5 tweeter and Faital 3FE22 midranges. The DE5 is so small that (with some fussy work with the mounting surfaces) the midranges can be positioned partly over the end of the tweeter driver to allow high crossover. That does require the waveguide to be conical down to the tweeter mounting, though, otherwise a throat transition would eat into the tolerable spacing from mid to the CD diaphram.

I have my current 'CoSyne' synergies now working linear phase (they reproduce decent square waves) using a passive crossover. A very complicated crossover on the tweeter to get that. Sure, it's easier with an active (done that, too) but I wanted to do passive for the challenge and to have a system that isn't too complicated for my wife to be able to turn on! The sound is really, really good (...so says the designer, as usual). I've never heard a real Danley Synergy, nor a Geddes speaker, so not much to compare to like that, other than SEOS-based designs (which were also quite good). I do find I really like the everything-from-a-point sound that Synergy horns give compared to separated 2way waveguide speakers, though maybe some of that is just psychological (because of the engineering elegance).

As noted yesterday, I managed to get ahold of a set of the Celestion midranges used by Tom Danley. ($132 per speaker.)

I put my Gentos up on eBay for about ten bucks a set, if anyone is interested.
 
As noted yesterday, I managed to get ahold of a set of the Celestion midranges used by Tom Danley. ($132 per speaker.)

Did Danley ever use Celestions? I thought he used Misco only. I know Spencer down in Oz used the TF0410 on his PS144.

It's convenient the TF0410 drivers are available easily now, as I'm using them (actually, only 1 per speaker!) in my newest design (the "SmallSyns"), which are playing very nicely now and waiting for me to get a full suite of measurements on. And waiting for me to finish the writeup on the thread I have going here after that. I'm pretty sure I like the new design better than the CoSynes even, up in our living room without room treatment they are sounding just stellar. I'm going to build myself a set of shelf-ported SmallSyns and probably put the CoSynes up for sale.
 
Its not 1/2 or 1/4 Sd. Its not a matter of compression ratio. Its a matter of tuning response shape around crossover with port area and port length, best done in simulation. Also note effective port length can be reduced by creating a frustrum around the port and smaller is better. You make the hole as small as possible consistent with your bandwidth requirements and checking that particle velocity in the port doesn't get too high at high volume.

In my "Synergy Corner Horns.." I used one 1/4" wide, rounded end slot per 4" driver, each slot 5/8" long. The horn walls were 12mm but thinned down to half that in the vicinity of the slots to create a frustrum. That is the smallest I've heard anyone make work. If you start there, you can always make them bigger.
 
Its not 1/2 or 1/4 Sd. Its not a matter of compression ratio. Its a matter of tuning response shape around crossover with port area and port length, best done in simulation. Also note effective port length can be reduced by creating a frustrum around the port and smaller is better. You make the hole as small as possible consistent with your bandwidth requirements and checking that particle velocity in the port doesn't get too high at high volume.

In my "Synergy Corner Horns.." I used one 1/4" wide, rounded end slot per 4" driver, each slot 5/8" long. The horn walls were 12mm but thinned down to half that in the vicinity of the slots to create a frustrum. That is the smallest I've heard anyone make work. If you start there, you can always make them bigger.

Thanks for your info, because this was the only thing I did not now quite well, I do not use 4 drivers but two mid and two bass and a high, but also think about a wideband and bass en a K-tube version to experient with, how ever first the circlotron has to be ended.

Thanks again, I go play with hornresp port dimensions.
 
I have play some with the ports, with a very cheap woofer and a more expensive beyma woofer, possible it is better to use a cloth surround version of woofer because of compression in front.

regards
 

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Sorry to bring up an old thread but I figured best to ask here. I am slowly getting my parts together but wanted to know what kind of port velocities do I need to aim for?

I looked at 500cm-800cm for port sizes and they still have quite high velocities. 45m/s+. So what is the aim with four 15's on a horn such as the SH64?
 
Good to know that the Beast is still alive!

Backtracking through my notes I found this by JLH:

The nice thing about Akabak is you can look at the air velocity of the mid ports while adjusting the applied power. I keep the air velocity below 17 meters/sec for good sound quality. Big mid ranges with small entry ports is generally not a good idea. You can run into air non-linearity with surprisingly low powers. If you want to go small on the mid entry ports, then use small mid ranges.
 
I am not worried about midrange port holes just bass driver port holes. I am not looking at the actual SH in front of me so I wondered what DSL's might be for four 15's?

From what I can see it looks like about the Sd area of a typical 4-5" driver for the port holes on the SH64. So thats only about 50cm2. So times four and we are only looking at about 200 to maybe 300cm2. That is not big enough to keep velocities down 35m/s or the tiny 17m/s. I have a 800cm port size and looked at 1000 port size also. 1000 looks best but length it starting to get a bit long.(50cm) 1000cm2 = 38m/s and 800cm2 =48m/s and all of these velocities are at 140db.
 
20% of Sd is usually a good starting point. For a 15" driver that is about 160cm2 each. Flaring the port will make the usable velocity much higher, have a look at the FlareIt calculator on the diysubwoofer page. Also the higher the frequency the velocity peaks at the more objectionable it is.

If you reduce the volume under the cone you can often make the port much shorter and get away with it having less diameter, have you tried that?

At 140dB you will need a massive port to keep the velocity under control without a volume reducer.

What have you been using to calculate your velocities so far?
 
If you mean a reflex port then most of the same applies, flare the port and you can use it to higher velocities, make it as big as possible or increase the size of your enclosure. Longer vent lengths can be made with gently rounded elbow connectors or slot ports built into the cabinet.

Same theory and solution as any standard reflex enclosure.
 
Sorry for the confusion. I am asking about the ports for the low end of the 15's. So not the highend. These 15's will be in about 180l and tuned to 45hz roughly. For the highend side that is much easier to deal with its the lowend side that is moving a LOT of air that I am concerned with.

Are you going to have both the vent and the cone ported into your Synergy horn? The highest velocities will be associated with the vent, I think, allowing the main port to be smaller. You should consider porting the vent through the baffle instead of into the horn. There is no doubt 45 Hz will be below its pattern control frequency.

These ports should be "frustrumized" to reduce the effective port length which will also allow you to use smaller holes.

A HornResp sim will allow you to find optimal port sizes and predict velocities.
 
I was looking at porting my 15's into the horn just like the synergy horns of DSL. So normal "4th order," on the mids and then 6th order on the 15's with the 45hz port exiting into the horn mouth.

Just like it is here in Danley's.
SH-64-Front-cropped1.png


They dont look like large ports in the picture but will have to see what I can fit. I also dont know exactly what volume I will have in my cabinet since it will be possibly larger than the SH64.
 
re'
all of these velocities are at 140db.

why on earth do you want to do 140db in your shed? you won't listen that load for long, or, if you do, you won't hear anything for long.

Seriously, the velocities go up with SPL so of course you are seeing high velocities. Chances are you won't hear the air noise at those sound levels. Turn down the level and the air noise will go away.

If you could be satisfied with just 6 db less SPL, you could cut back from 4 woofers to 2 and save a bunch of money as well as reduce velocities
 
Thanks PB. And if you look at 2.5" ports for the woofers that is quite high for velocity also.

This wont be for just my shed. I am planning on using these speakers for an outdoor cinema. When they are in the shed they will be used at much lower volumes. I am just planning on keeping velocities down at its max potential. Plan for maximum and use 75%. Thats the idea anyways.