GoodSoundClub - Romy the Cat's Audio Site

09-28-2013

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Romy the Cat

Boston, MA
Posts 10,166
Joined on 05-28-2004

Post #:	21
Post ID:	20103
Reply to:	20102

A word of warning

II would like to pass a word of warning about the C-15W driver. I do not know this driver but it looks like it has dual voice coil. This might be a hell or blessing. On a paper the idea sound very interesting but unfortunately when I seen it it never worked. University had M4 driver with dual voice coil and it truly very bad sounding driver. You need to make you own subjective judgment about the C-15W driver. Put it in 3x5 or 2 x4 open baffle fame and listen it for a while. Use it if you like it. Still, make a provision to be able to put in your back chamber another driver if C-15W will not work out for you.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

09-28-2013

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Paul S
San Diego, California, USA
Posts 2,664
Joined on 10-12-2006

Post #:	22
Post ID:	20105
Reply to:	20101

Choosing the Pivot Point

Scott, it sounds like you have properly tempered your expectations and steeled yourself against the very real possibility of "problems" over the course of developing this channel. Is the Dean originally designed +/- as a corner horn, and do you plan to use it +/- this way?

I would not say the 515s are toys, rather people seem to insist to make them play ULF, which they are not suited for. In the A7 bins, they dropped off like a rock below 50 Hz, and to push them below this will at least take exponential power, along with the "special" X/O, and all that comes with that. I don't know the other driver you mention, or how it would suit that cabinet. No doubt you have done your homework, and you have built in ways to accommodate it over your desired frequency range. Anyway, from what you say, it sounds to me like you will be making this channel the "pivot" of your speaker, and if this is the case, then you can probably make it work, one way or another, once you get it voiced to suit yourself.

Best regards,
Paul S

09-28-2013

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skushino
Seattle, WA
Posts 93
Joined on 07-07-2004

Post #:	23
Post ID:	20106
Reply to:	20103

Pictures - Third Time's a Charm

Another very quick post - I have guests arriving from Japan in a couple of hours. Will respond more thoughtfully when I have some free time.

University Dean plans:

Mouth - 1080 in^2

Throat - 78 in ^2

S(d) - 132.7 in^2

Compression ratio - 1.70

Path length ~ > 1.3 m

If my math is correct, the profile should be valid for horn loading down to around 55 Hz

university dean plans-2.jpg

C-15W Dual Impedance Woofer:

This woofer does in fact have dual coils. Agreed this is one of many unknowns affecting the sound. I like the idea of having the ability to vary the impedance as another tool in shaping the final sound. In addition to these drivers, I have others to audition in this horn, including Altec 515G and EVM-15. The back chamber in the horn appears adequately large to optimize for various drivers.

University C-15W.jpg

C-15W Nude:
University C-15W Nude.jpg

Dean Horn Exposed:
Dean Horn Exposed.jpg

09-28-2013

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Jorge
Austin TX
Posts 141
Joined on 10-17-2010

Post #:	24
Post ID:	20107
Reply to:	20103

100 hz

Skushino, I found the same thing, TH can only go so high before they start sounding :funny, of course due to the principle involved, if you want to raise the response further from the design the same Tapped Horn begins to work against itself. So one option could be to redesign a tapped horn that would go higher.
Now you state that your TH can go up to 90hz with good sound. But your UBH only goes down to 140 hz, maybe a little lower due to the fact that it is coupled to the floor.
If you make your UBH bigger say 110 hz- 100 hz it would go lower with the same sound you already like.

I fnd it hard to go into unchartered territory trying to make, get to sound good and then integrate a horn that you have no idea how it will sound.
I had for a couple of years a pair of Hartsfield top loaders, I hated them...

09-28-2013

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skushino
Seattle, WA
Posts 93
Joined on 07-07-2004

Post #:	25
Post ID:	20108
Reply to:	20107

Tapped Horn Application

Guest napping now from 16 hrs jet lag, so I have a moment...

Jorge, you raise an interesting point about THs. I may be incorrect in assuming THs sound worse as they play higher in freq. Perhaps instead the limitation is one of narrow bandwidth rather than frequency. In other words, having my TH cover 20 - 100 hz, more than 2 octaves, may be a bridge too far. 20 hz is a very different operating point compared with 100 hz. Sure the system works, but to my ears definitely sounds better when i fix the high pass around 18hz and lower the crossover from 90 to 70 hz. I have a hunch one could design a TH suitable for playing higher frequencies, but in a narrower BW. But I can't think of any practical reason to do it.

No doubt a 100 hz UBH would be fantastic compared with my 142 hz horn. We always want our bass horns to be a little bigger, right? But using the horn to play lower comes at a price - I would want to lower the upper crossover point too, meaning my MR horn playback needs to go lower. And unless I made an even larger folded horn to go lower than 50 - 55hz, the larger UBH just squeezes the operating bandwidth of the folded horn narrower, in this case 50 to around 80 or 90 hz (with boundary and room gain applied to UBH). In that case the effort of building a dedicated mid bass channel is hardly worth operating in a bandwidth less than an octave. So I think if one is using a dedicated mid bass channel under the UBH, maybe 140hz or similar is a good decision for this application.

bty, thank you for sharing the results of your mid bass experiments - your experience is educational for me, and you're one of the few with an opinion informed by real world experience.

09-30-2013

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Romy the Cat

Boston, MA
Posts 10,166
Joined on 05-28-2004

Post #:	26
Post ID:	20110
Reply to:	20108

Tapped Horn buzz word.

It is not the thread to talk about Tapped Horn but listening to what you Tapped Horn users saying I do understand my suspicions about the concept. I can’t objectively judge sound from Tapped Horn as I did not hear any properly made, calibrated and inhaled but I wonder why people so love the Tapped Horn buzz word lately? To cover any more or less low extensions a Tapped Horn need to be large and peaty much comparable to sealed enclosure. Why then do not use sealed enclosures that are free from any many problem and very predictable in sound?

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

09-30-2013

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Jorge
Austin TX
Posts 141
Joined on 10-17-2010

Post #:	27
Post ID:	20111
Reply to:	20110

Tapped Horn Sound

Actually a Tapped Horn would be bigger than a sealed enclosure, here is one of my first TH tests. The sound is very different than the sound coming form a Sealed encolsure. My first impression was that the bass was gone! There was no bass sensation in the room anymore, no chest thumping, lets say (which is a wrong term). After a while you realize that the bass is there and all the frequencies played by the instruments are present, it sounds like a bass is playing in the room, but we have grown accostumed to hearing sealed and ported enclosure bass, and IME this bass generates a sort of accompanying bass sound that is not generated by any instrument, a sort of fat bass sound that can be very rewarding. Lets just say that TH bass is much cleaner and generates a different "bass sensation" in the room. Once you get used to it, it is very difficult to go back to boxed bass.
I find the sound similar to what a Mid bass horn woud play.
Romy what differences in sound did you find when you changed from your Scanspeak Bass array to the big MB horns?

Tapped Horn a.jpg

09-30-2013

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Jorge
Austin TX
Posts 141
Joined on 10-17-2010

Post #:	28
Post ID:	20112
Reply to:	20111

TH design priciple

Skushino. Yes TH is designed to play 2 octaves and no more, this derives from the design which actually uses a labrynth, in the shape of a horn, to return (and amplify) the back wave of the driver to the front and add its strenght to the output, now on phase, of the front wave of the same driver. Of course it can be stated that a time delay might be introduced though, but not too noticeable at this low ranges. In order to make the back wave come around to the front one designs a specific lenght for a specific frequency: For example, your 20 hz TH would be designed for a 40 hz wave to go around, and it would be usable from 20 hz to 80 hz, one octave below and one above, before terrible distortions begin to wreak the front wave. This is why fourth order Xovers are necesary as Low pass and High pass at these frequencies. Using a TH beyond this range is not reccomendable. You cannot change these frequencies without changing the lenght.
Now if you design a TH for 70 hz, you can use it from 35 hz up to 140 hz, and that could match up to your 142hz front Upper Bass horn.
With this solution you completely eliminate the need for a Folded horn midbass channel, that was my point since the begining.
Either lower you Upper bass solution with a bigger horn to play down to 100hz or raise your bass solution to play 140 hz.
But, of course you can make the folded horn and tell us how it sounds! I would be very interested.

09-30-2013

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Romy the Cat

Boston, MA
Posts 10,166
Joined on 05-28-2004

Post #:	29
Post ID:	20114
Reply to:	20111

Either of them.

Jorge wrote:
Lets just say that TH bass is much cleaner and generates a different "bass sensation" in the room. Once you get used to it, it is very difficult to go back to boxed bass.
I find the sound similar to what a Mid bass horn woud play.

Interesting….

Jorge wrote:
Romy what differences in sound did you find when you changed from your Scanspeak Bass array to the big MB horns?

I do not think that I can tell the difference more or less credibly. It was in different room. It is not to mention that I very much still use the Scanspeak Bass array only now they work when they do best – in ULF zone. Frankly what I used Scanspeak array for upper bass in old smaller room then I had no problem with the way how they sound, at least how it was done in my installation.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

09-30-2013

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Romy the Cat

Boston, MA
Posts 10,166
Joined on 05-28-2004

Post #:	30
Post ID:	20115
Reply to:	20112

TH horns Triptych?

Jorge wrote:
Now if you design a TH for 70 hz, you can use it from 35 hz up to 140 hz, and that could match up to your 142hz front Upper Bass horn. With this solution you completely eliminate the need for a Folded horn midbass channel, that was my point since the begining.

Intersting. I do not know anything about the TH horns sound but if what you say is true then why do not come up with 3 TH horns: lower bass at let say 30Hz, midbass at let say 80hz and upperbass at let say 150Hz.This array of TH horns will cover all bass rage and if to locate them time-aligned then it might be a solution. One can complement the TH up-down Triptych (or Diptych) with ULF sealed channel and HF horns and it would be it? I did not see anything like this but if people do love theirs TH horns then why doesn’t they do it?

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

09-30-2013

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Jorge
Austin TX
Posts 141
Joined on 10-17-2010

Post #:	31
Post ID:	20116
Reply to:	20115

Returning the wave

Well the thing is that the returning wave from the back side of the driver, does return in phase, but "later" than the front wave, logically. This should add some distortion that I have not noticed, but of course and worried for as much as I am worried for the unused RCA conectors in my preamplifier, or the brand of cable lifts I will be using...
Making a TH for a higher frequency is actually much easier since the labrynth would be much shorter. I have several designs for this but never made them due to this concerns.
So for the frequencies below our UBH it works nicely, I am sure it would work even better as ULF, but it would be prohibitively big, well much bigger than a selaed enclosure Sub which can be pretty small with a long throw subwoofer that will do the job.
Now to use it instead of my UBH: I have seriuos reservations, but never tried it....
TH do have a lot of cabinet walls and if not treated properly (a lot) any small cabinet reverberation colors the sound terribly.

10-01-2013

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Romy the Cat

Boston, MA
Posts 10,166
Joined on 05-28-2004

Post #:	32
Post ID:	20119
Reply to:	20116

An interesting system design possibility.

Again, I am not in position to make any judgment about the Tapped Horn as I still do not know if it is produce faulty sound or not but from design perspective a Tapped Horn opens some interesting design possibility. If the horn is large then it still has very small mouth and it very easy could be placed through a floor or wall with the body of the horn is hidden let say in a basement and with only very small part of it extended in a listening room. Hypothetically a top of the Tapped Horn might serve like a frame for MF horns…

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

10-04-2013

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Macman
Stockholm, Sweden
Posts 10
Joined on 10-27-2011

Post #:	33
Post ID:	20125
Reply to:	20102

I dont use my tapped horns any longer because..

Hi,

I dont use my tapped horns any longer because of the annoying peaks above the usable frequency range. Some how they managed to excite a room node at 60Hz that none of the other bass solutions I have tried messed with. They also didnt have the output I wanted. Currently I use a pair of backloaded horns which I might rebuild to frontloaded if Im not content with the 8 closed boxes with jbl W1500H which at the moment are first on the construction list.

/Macman

10-05-2013

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Romy the Cat

Boston, MA
Posts 10,166
Joined on 05-28-2004

Post #:	34
Post ID:	20126
Reply to:	20125

Room infirmity.

Macman, the “annoying peaks above the usable frequency range” is something that your specific installation might have in context of your room and your acoustic system location but it might not be a characteristic of tapped horns. I do feel that tapped horns might be more room picky as the radiation surface is very small in them. In your correct case of dipole it is for sure more room forgiving.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

10-06-2013

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Rewind
Posts 20
Joined on 04-15-2013

Post #:	35
Post ID:	20131
Reply to:	20126

Forget midbass, Fane got it covered.

I take it back, 100Hz is pushing it regarding horns and compression drivers I know of. I can't imagine a compression driver reaching the midbass muscle of the Fane S 8M. And I don't see why one should try, when the Fane reaches 120Hz so effortlessly. However... midbass is complicated. Smile

With the Fanes I still hear the mud in comparison to other solutions.

10-06-2013

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skushino
Seattle, WA
Posts 93
Joined on 07-07-2004

Post #:	36
Post ID:	20132
Reply to:	20126

More TH

Had a wonderful visit with my Japanese friend. But now she's flying West over the Pacific, and I wanted to add my experience to the TH discussion.

The main benefit of the TH is the relatively small mouth compared with a traditional horn.

That's all. Nothing more. THs aren't magic. They need similar volume as alternative bass topologies for a given frequency range. They aren't louder. They don't play deeper. All they do better is have a smaller mouth. This allows a more convenient form factor than a traditional horn, usually a tall slender tube or a large flat box. This allows some placement flexibility. Given real estate limits that most of us cope with, the TH can be a useful tool in some applications.

If I had unlimited real estate and placement options, I would NOT use a TH. The reason being the narrow BW and 'spikey' response above the design BW.

I thought about Romy's triptych idea a couple years ago. The form factor is potentially very attractive. But it's not for me. Given the sole TH benefit is form factor and packaging, then it makes sense to leverage this advantage in an application with the most potential to benefit - this is ULF. Any ULF device needs to be physically large. The TH simply presents an attractive packaging option.

I never came up with a satisfactory reason to use a TH above the bottom ULF channel. A folded midbass horn and straight front horn UBH solution, executed well, have less compromises compared with a TH, in a similar volume. Disclaimer - I never built a small TH for mid and upper bass frequencies. But why would I? I have no interest in testing this concept.

10-07-2013

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Romy the Cat

Boston, MA
Posts 10,166
Joined on 05-28-2004

Post #:	37
Post ID:	20133
Reply to:	20132

Nothing yet.

Scot, I disagree with your comment about TH have “relatively small mouth compared with a traditional horn”. It is not about the mouth size – you can’t compare two very different topologies directly only on the merit of mouth. I very much like you skeptical about HT and equally to you unexpended but I am not willing to legislate based upon my suspicions. Do not forget that the “testing the concept”, even if you undertake it would not give a verdict to the whole HT horn idea as it would be, or might be, just a specific result of your specific installation, implementation or expectation. So, I do not know what the relation of your Japanese friend has with HT horn but the fact that he made you to think about the small mouth does make me feel that he is uninformed as you and me.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

10-07-2013

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skushino
Seattle, WA
Posts 93
Joined on 07-07-2004

Post #:	38
Post ID:	20134
Reply to:	20133

TH Small Mouth

My point was simply that my interest in THs is because of the form factor, rather than any perceived sound benefits compared with traditional horns. To my way of thinking, THs are a specialized tool for a very specific application - ULF.

10-28-2013

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Rewind
Posts 20
Joined on 04-15-2013

Post #:	39
Post ID:	20217
Reply to:	20039

Evaluating two midbass horns.

Tonight I finished two horns at once. One was a shortened Goto S-150 horn that now has a Fane S 8M, without back chamber so far. Dimensions are now 1.1m deep, 11cm throat, 75cm mouth. It is replacing the Avantgarde Trio midbass horn replica with a Fane S 8M with back chamber.

I was spending the weekend with hornresp, and I could not get the Avantgarde Trio midbass horn to simulate very well, which explained my mixed feelings about it.

I am liking this setup better. I don't shiver when I cross the Fane up to 600Hz.

The other horn I finished is a Kugelwellen horn inspired by Trio mid horn that goes down to approx. 550Hz. This horn I am mighty pleased with. Minor adjustments left at the throat. The previous version was made in newspaper and tape. They sound similar, although pine tree and oak was a better idea. Smile

The two top horns in the Avantgarde Trio is probably the only horns I will still be impressed by. I should not say those things when I have not heard the original yet.

I do miss the large Goto S-150 horns but I will fix that with a JMLC-200T inspired horn later. It sounds too sensible now. Too correct. I would not say boring, since it is still horns. I have given up on the WE 15A though. I have found my perfect drivers and these babies will not play lower than 300hz anyway. 340hz will be a good enough goal.

The next midbass horn, if I ever design it, will be a JBL 2202H in a 50Hz straight horn, or more realistically, a J horn.

Current setup:
JA6681B in a shortened JBL HL 14-25: 3500-12 000Hz
JA6681B in own Kugelwellen horn: 600-3500Hz
Fane S 8M 8 ohm in shortened Goto S-150: 95-600Hz
LAB12, still in boomy sonotube 35-95Hz Sad

11-06-2013

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Macman
Stockholm, Sweden
Posts 10
Joined on 10-27-2011

Post #:	40
Post ID:	20242
Reply to:	20126

FIR

Romy the Cat wrote:

Macman, the “annoying peaks above the usable frequency range” is something that your specific installation might have in context of your room and your acoustic system location but it might not be a characteristic of tapped horns. I do feel that tapped horns might be more room picky as the radiation surface is very small in them. In your correct case of dipole it is for sure more room forgiving.

I know my room isnt very good. The tapped design is rather appealing but I couldnt make it work. Im sure they are good for some specific tasks but for hifi, I dont think so. My tapped horns are going out the window.

Any way, I had a friend over the other day who had made his own FIR filter. We made sweeps for every driver, more or less phase and delay adjusted the whole hornsetup and configured the filter and what a difference. I had a minidsp before which according to me, did a decent job at the heart of the setup but I no longer want to reconnect it. The bass is so tight you hardly believe its there somehow. I believe that FIR filters is the way to go with horn setups due to the phase problems caused by the horns themselves. Does anyone have any experience with FIR filters?

/Macman