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04-23-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,511
Joined on 05-28-2004

Post #: 1
Post ID: 10333
Reply to: 10333
The tapped horns: cons, pros and Sound
fiogf49gjkf0d

Somebody "KCCT82"  from Devil Audio site posted information about own installation.

Channels:

TAD ET-703 compression driver <12k-20k> (107db 8 ohms)
TAD TD-4002 compression driver on 400hz tractrix <1.9k-12k> (110db 16 ohms)
GOTO 505TT compression driver on GOTO 150hz hypex <250-1.9k> (110db 16 ohms)
TAD TL-1101H cone driver on DIY 1/2 space 53hz hypex with 5" throat <58-250> (around 103db if not more... 16 ohms)
TAD TL-1603 cone driver on DIY tapped horn <20-58> (around 95db... 8 ohms)

All channels are active, crossovered and EQed by Behringer DCX 2496 and powered by 5x100W SS PP pro audio power amps.

I am posting some images of the setup. With all mistakes made in this installation some of the moves made in there are pretty good - I like the upperbass horn with 5" throat and 58Hz mouth. It is unquestionably that in this configuration there is no need to talk about Sound. Still, there is the point in this installation - the use the tapped horns between 20-58Hz, that I would like to accent.

5ch_TADs-1.jpg

5ch_TADs-2.jpg

5ch_TADs-3.jpg

5ch_TADs-4.jpg

5ch_TADs_5.jpg

5ch_TADs-7.jpg

John Hasquin told me about his 20Hz tapped horns very positively. I do not know… as the idea of the series resonant chambers is not to my liking. Still, I never heard an offensively-made tapped horns and I have no idea what kind sound people get from it. Sure, the notion to get 20Hz from 2 feet by 2 feet of footprint sounds so sexy. How that tapped bass sounds and can this horn to play properly “soft” bass is the bigger question.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-26-2009 Post does not mapped to Knowledge Tree
ferenc
Posts 7
Joined on 02-16-2008

Post #: 2
Post ID: 10359
Reply to: 10333
Danley PA speakers
fiogf49gjkf0d
Hi Romy,

You should have to check Tom Danley's speakers at http://www.danleysoundlabs.com/. He has quite a few tapped horn subs and Synergy horns for PA, but there are people using his speakers at home, like
myself. I have changed from Avantgarde Acostics Trio horn speaker to his SH 50 then to SH 100Bs, but I use his SH 100 and SH LPM for different PA and Home Theatre projects.

ferenc
04-26-2009 Post does not mapped to Knowledge Tree
tuga


Posts 174
Joined on 12-26-2007

Post #: 3
Post ID: 10360
Reply to: 10333
KCCT82 has posted at goodsoundclub
fiogf49gjkf0d
Romy,

KCCT82 has posted here before:

http://www.romythecat.com/GetPost.aspx?PostID=8696


Cheers,
Tuga


"Science draws the wave, poetry fills it with water" Teixeira Pascoaes
04-27-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,511
Joined on 05-28-2004

Post #: 4
Post ID: 10369
Reply to: 10359
The Tom Danley's tapped horns.
fiogf49gjkf0d

 tuga wrote:
KCCT82 has posted here before:

http://www.romythecat.com/GetPost.aspx?PostID=8696

Yes, Tuga, I realized the he was here. The tapped horns and the midbass horn was an interesting move but the use of digital crossovering option and SS PP amplification of course set all bets off and make the installation boring to even to think about.

 ferenc wrote:

You should have to check Tom Danley's speakers at http://www.danleysoundlabs.com/. He has quite a few tapped horn subs and Synergy horns for PA, but there are people using his speakers at home, like myself. I have changed from Avantgarde Acostics Trio horn speaker to his SH 50 then to SH 100Bs, but I use his SH 100 and SH LPM for different PA and Home Theatre projects.

Thanks, ferenc. I know that Tom Danley is out there with his horns but I never looked what he does. The Avantgarde Acoustics Trio bass sections of cause were good for nothing. No wonder that you like any alternative option. The Danley’s site has a paper about tapped horns, I read about it but I generally do not get a lot of useful information from “white papers”.

http://www.danleysoundlabs.com/pdf/danley_tapped.pdf

The same was here, I disagree with some of the Danley’s statement and I found that some of his comments are just irrelevant from the perspective of how Sound is made. Still, I did not hear the Danley’s tapped horns and I have no idea what he is trying to do.

Anyhow, Tom Danley looks like has an interesting small footprint horn that is similar to what KCCT82 uses.

http://www.danleysoundlabs.com/pdf/DTS%2020%20Spec%20Sheet.PDF

Again, I am bit defensive about some of the horn characteristics and what I read between the lines but who knows, if I heard it in context of a rational installation then I would be able to say something definitive. I generally, as you might read before, am against the “open bottom” horns and consider them as a topological mistake. Would the Tom Danley’s trapped horn be an evidence of it or will it be able to battle my reasoning? I do not know. The trapped horn idea, from what I can see, has all justification to become a quarter-ass solution or the solution for the people who hear via SPL and “white papers” but, despite me do having some negative premonitions, I would hold my final judgment.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-28-2009 Post does not mapped to Knowledge Tree
serenechaos
lost alamos
Posts 86
Joined on 12-01-2007

Post #: 5
Post ID: 10383
Reply to: 10333
Soft bass
fiogf49gjkf0d
I built a pair of tapped horns, as per John Hasquin, designed to integrate w/ mid-bass horns (cross over ~ 70-80 hz). 
Loaded in the corners, the low bass is well supported, and, they "dissapear" sonicaly. 
By that, I mean, they don't "stick out" at all, I don't notice them unless I unplug them. 
The term "soft bass" comes to mind, and very much applies, if we are thinking the same thing. 

04-29-2009 Post does not mapped to Knowledge Tree
Kcct82
Beijing, China
Posts 23
Joined on 09-08-2008

Post #: 6
Post ID: 10386
Reply to: 10333
Tapped Horn Noob
fiogf49gjkf0d
Hello Romy,

The tapped horns were easy to construct so I made them while I was working on the midbass channel. I can't really comment on how good tapped horns are because I have never heard other 20-35hz capable systems... it does provide amazing SPL's and to my dad and I, the sound is good. I do not understand what you mean by "soft" bass but like Serenechaos have said, it does not "stick out".

There's another thing perhaps due to tapped horn positioning, my previous -10db at 40hz, +11db at 51hz, and -10db at 60hz are now much less severe.  

Honestly the tapped horns are the least of my problems right now... like you have pointed out, the electronics is a mess, placement for the 3 upper horns is another issue, crossover points and tractrix horn building...

Best Regards,
Keith

04-29-2009 Post does not mapped to Knowledge Tree
tuga


Posts 174
Joined on 12-26-2007

Post #: 7
Post ID: 10387
Reply to: 10383
Hasquin's tapped horns
fiogf49gjkf0d
 serenechaos wrote:
I built a pair of tapped horns, as per John Hasquin, designed to integrate w/ mid-bass horns (cross over ~ 70-80 hz). 
Loaded in the corners, the low bass is well supported, and, they "dissapear" sonicaly. 
By that, I mean, they don't "stick out" at all, I don't notice them unless I unplug them. 
The term "soft bass" comes to mind, and very much applies, if we are thinking the same thing. 


Hello serenechaos,
I'm curious about the configuration your Hasquin's tapped horns.Would it be possible for you to upload a photo?How about sound? Bowed double bass is hard to reproduce and I guess it should definitely not sound "percussive"...
Cheers,Tuga


"Science draws the wave, poetry fills it with water" Teixeira Pascoaes
04-29-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,511
Joined on 05-28-2004

Post #: 8
Post ID: 10389
Reply to: 10386
Why no hoodlums build horns in Massachusetts?
fiogf49gjkf0d

It sucks – whoever builds horns too damn far! I need to see my congressmen to lobby lowering taxes for horn users of something like this….

Anyhow, the “erenechaos” comments about the “soft bass" is a good sign, though of course to equalize the coordinate systems of judgments is possible only sitting in the same room, listening the same installation and compare the notes…

With all of my negative predisposition in regards to the curved re-entry horns (that the tapped horns are basically are) I have to admit that it is not my major concern about the tapped horns.  My major concern is that the tapped horn is close- bottom horn and it is something that I very much do not like and why I generally extend my support to midbass horn but denounce the lower bass horns and conceptually faulty devices. The tapped horns are essentially the same – the “close bottom” horns – I do not like the idea, at least on paper.

The problem with rectification of the conteversy about the importance of “open bottomless” ironically lays in the attitude of many audio people as they in majority are very close-minded and so obsessed with own accomplishments that refuse to engage or even to recognize realty of accomplished. It is no surprise that the worst lower bass I heard was from the installations where people invested a lot of efforts to build that lower bass via bass horns. Anyhow, if is known that I am not a big supporter of the lower bass horn solution.

What I say is not directly applicable to tapped horns, even despite they are “closed bottom” solution as well. Perhaps something in them the cancels out the negative effect of “closed bottomness” – I do not know – I need to hear the thing to say anything more defiantly.

I remember a few years back John Hasquin  posted a lot of information at TriodeMafia web site about his carnal relations with tapped horns. I was banned from TriodeMafia because I expressed my strong desire for one of their assholes (Ed Sawyer) a soon and very painful death. I hope that this paces of human waste is already dead and the TriodeMafia might invite me back, if not then I wish that Ed Sawyer would dies very slow and agonizing with great suffering to anyone who knows him (I am not kidding)  - he and anyone who associated with him are well deserve it. Anyhow, John at that time send a lot of information about his view and his progress on tapped horns, I need to found it somewhere and to reread.

Keith, is your tapped horn also John Hasquin ‘s implementation?  Serenechaos, what do you use above 10kH, what is your midbass solution and how you crossover your tapped horn? Also, what is the dimension of the thing? Furthmore, are of you guys who use the tapped horns looked the different versions of the tapped horn,  let say Hasquin ‘s and Tom Danley's tapped horns?

Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-29-2009 Post does not mapped to Knowledge Tree
serenechaos
lost alamos
Posts 86
Joined on 12-01-2007

Post #: 9
Post ID: 10392
Reply to: 10389
Economic stimulus package for horn building hoodlums?
fiogf49gjkf0d
I do not know what is meant by “close bottom” or “open bottomless”-- please expound?
I do not know of importance of enemys death to this topic.

There is a long thread in the subwoofer section of "devil audio" about tapped horns. 
John mentioned getting a flatter response than I was able to using the same driver (4012HO definemax) I was working with. 
I wrote, asking for advise, he suggested adding a inductor in series w/ the driver. 
Also cutting the throat the full size of the driver, not smaller for compression ratio (!!!) 
He has built others since, is now using two drivers per cab; and says it works better. 

I looked @ many designs, spent a while studying Danley's & the patent trying to figure out what was going on with it, and the resonators, etc. 

Size of the THs I built is ~ 16" x 16" x 80". 

implementation--ok, here we go; now none of what I said means anything... 
different room, different system... 
mine is all "unfinished/evaluating/work in progress;" experiments--listen, change, listen, repeat at this point... 
only the tapped horns, and "what I use above 10kHz" stays.  
passive line leval crossover, seperate amps.  
This is all building towards:
the tapped horn is to ~70Hz. 
a mid-bass horn from ~70 - ~500Hz. 
a low-mid horn from ~ 500 - 1kHz. (what you call fundamental channel)
a high-mid horn from ~1kHz - 10kHz. 
a ribbon from 10kHz up. 
04-29-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,511
Joined on 05-28-2004

Post #: 10
Post ID: 10393
Reply to: 10392
Looking at the tapped horn further…
fiogf49gjkf0d

 serenechaos wrote:
I do not know of importance of enemys death to this topic.

Oh, this is a sheer pleasure but do not call that dirt enemy. He is not enemy but way beyond it, he is the person about whom I have a death-wish as pure self-pleasuring. Think about him like people thought about Hitler and think how pleased some people would be learning that that son of bitch choked to death. Enemy implies a conflict of interests. He is no enemy, in fact I have no idea who he is and what his interest are. However, knowing his actions I sincerely feel that he is out of presentences of any civilized treatment and that he shall be literally exterminated like some kind of virus or very filthy bacteria.

 serenechaos wrote:
I do not know what is meant by “close bottom” or “open bottomless”-- please expound?

I have expressed those views of mine many times and this is one of my major reasons why I am not so excited about use of bass horns for the lowest channel of playback. In the past I wrote in the “Barn Conversion - James' Project” thered:

"The sealed enclosure I call “opened bottom” enclosures. What I mean is that there are no conceptual limitations in lower response. The limitations in sealed box are tactical: how much power you have, how much your drivers will handle, what is the relation of volume and Fs, how driver damped by amplifier and many others. However, there is no self-restricting boundary in there. With any other LF solutions (horn, open baffles, 4th order, ported and so on) there are always strategic limitations by nature of the design… would it be size of the baffle, size of the mouth or tuning of a port). With sealed box you can always burn some power, use the LF section on transition slope or even EQ (with open bottom only) your bass (works very well). With any other solutions (besides sealed box) those “further actions” are not available. Those are some of my motivations why I do not like the idea of bass horns and prefer the sealed enclosures"

Take a look what happed with any bass horn. In order to get proper sound out of any bass horn you must unload the lowest frequency from the horn, the frequency that are not able to be reproduced by this horn. This is a very big subject and I can talk for very long nowadays about the ways how the rule might be “banded”, but unloading of unused bass is very basic objective. BTW, the person who made me to think about it was John Hasquin.  That sharp explicit filtration of bottom knee of a channel is fine if you have another channel follow but if it is the last channel then it not good. Pretend that you have a tweeter with low pass filter. Did you ever try to use any anti-rambling filters in phonostages, those the kill under 20Hz of what they call TT noise and record warp noise? Di you see how it killed everything? So, those systems I call “closed bottom” and there is a sharp and definitive roll of at LF. Take a look what Tom Danley says in his tapped horn: 15 Hz with 24dB/octave of high-pass. You see it is the lowest channel in system and you have 4th order high-pass. I do not like this idea and I would like the lowest channel to have not explicitly restricted LF response, or something that I call “open bottom”.

 serenechaos wrote:
There is a long thread in the subwoofer section of "devil audio" about tapped horns.  John mentioned getting a flatter response than I was able to using the same driver (4012HO definemax) I was working with. I wrote, asking for advise, he suggested adding a inductor in series w/ the driver. 
Also cutting the throat the full size of the driver, not smaller for compression ratio (!!!) 
He has built others since, is now using two drivers per cab; and says it works better. 

I looked @ many designs, spent a while studying Danley's & the patent trying to figure out what was going on with it, and the resonators, etc.

Sure it is all very interesting but to have in an idea about what people are taking about discussing the quality of tapped horns it would be nice to hear one…

 serenechaos wrote:
Size of the THs I built is ~ 16" x 16" x 80". 

…and THIS is the deal-breaker….

 serenechaos wrote:
implementation--ok, here we go; now none of what I said means anything... 
different room, different system... 
mine is all "unfinished/evaluating/work in progress;" experiments--listen, change, listen, repeat at this point... 
only the tapped horns, and "what I use above 10kHz" stays. 
passive line leval crossover, seperate amps. 
This is all building towards:
the tapped horn is to ~70Hz.
a mid-bass horn from ~70 - ~500Hz. 
a low-mid horn from ~ 500 - 1kHz. (what you call fundamental channel)
a high-mid horn from ~1kHz - 10kHz.
a ribbon from 10kHz up. 

Very, lucid system!

So, you have a tapped horns at 70Hz and below. Does it mean that you do not use any high-pass filtration with your tapped horn? You said that you use passive line level crossover and separate amps. So, what is the bottom frequency response of the power amps that drive the tapped horn? Do those amps have any topological restriction of LF that might act at high-filter for you tapped horn?

Rgs, Romy


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-29-2009 Post does not mapped to Knowledge Tree
serenechaos
lost alamos
Posts 86
Joined on 12-01-2007

Post #: 11
Post ID: 10394
Reply to: 10393
No high pass
fiogf49gjkf0d

ahh yes, tapped horn is what you would call "close bottom."  It has to be designed around frequency response (which is very narrow band).  It isn't a problem getting one to go low enough though, and the quality of sub bass produced, smooth yet dynamic, present not overbearing, and volume per footprint per watt input was much greater than the sealed boxes it replaced. 

No, I do not use any  high-pass filtration, or feel any need to.  They have a steep enough acoustic roll-off, that i'm not at all worried about hurting the drivers @ the levels I play them at.  If I were using them for PAs, or stadiums, (as Danley customers usually do), then I'd be concerned about it. 
Same with thermal overload, and x-max, that devil audio guys worry about.  But they're using 1000 watt amps, and trying to see how much spl they can put out... 
I'm still in a "less is more" as far as adding electronics to the signal path. 
Again, like those anti-rumble filters in phonostages you mentioned, that kill everything, not just under 20Hz...   
 
Robert

04-29-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,511
Joined on 05-28-2004

Post #: 12
Post ID: 10395
Reply to: 10394
Rolling off the tapped horn
fiogf49gjkf0d
I think it might be very interesting to introduce the high-pass filtration for tapped horn and to see how it behaves. It is not only about thermal overload and restriction of excursion. The unloading of none-used bass generally clean-up the transparency of band-bass very positively. The benefits might wary with the drivers and the way in which the driver is damped. You might want to try it, get a cheap digital crossover and try different slopes between 10Hz and 20Hz. You would not need to listen the absolute quality but rather the pattern in which Sound night be changing. If you found that let say at 14Hz you would like to roll of your tapped horn with second Bessel order then you would always be able to implement it in your tapped horn’s bass amp.
 
The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-30-2009 Post does not mapped to Knowledge Tree
Kcct82
Beijing, China
Posts 23
Joined on 09-08-2008

Post #: 13
Post ID: 10396
Reply to: 10395
No filters below 20Hz
fiogf49gjkf0d
Hello Romy,

I didn't use John Hasquin's tapped horn design, I modeled my own in hornresp for my TAD woofer. I knew I would only need it up to ~55Hz so I was happy to have it flat from 23Hz-70Hz.

The lowest crossover point for Behringer DCX 2496 is 20Hz, I can try it either with or without a filter at 20Hz.  

Best Regards,
Keith
04-30-2009 Post does not mapped to Knowledge Tree
decoud
United Kingdom
Posts 241
Joined on 03-01-2008

Post #: 14
Post ID: 10397
Reply to: 10389
Prototype
fiogf49gjkf0d
Romy, I know you despise DIY, but isn't this so obscenely simple to build one may as well try it? Presumably, all one needs is a length of large diameter cylindrical pipe, with a partition running down the middle? If one uses two pipes of slightly different diameter, with sand poured between them, even the material the pipes are made of would not matter, no?
04-30-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,511
Joined on 05-28-2004

Post #: 15
Post ID: 10398
Reply to: 10397
What is going on with tapped horns...
fiogf49gjkf0d
 Kcct82 wrote:

I didn't use John Hasquin's tapped horn design, I modeled my own in hornresp for my TAD woofer. I knew I would only need it up to ~55Hz so I was happy to have it flat from 23Hz-70Hz.
The lowest crossover point for Behringer DCX 2496 is 20Hz, I can try it either with or without a filter at 20Hz.  

Keith, this experiment must NOT be done blindly as it will absolutely defeat the purpose if it done methodology incorrect. You will have the “change” in sound but you will not know if this change was due to the high-pass filter truncated response itself or because it unloaded the unused bass. You need to run very high resolution of RTA at the bottom knee of your tapped horn and to see if your high-pass does not cut the tail of the natural response. Theoretically the filter must kick in right after then but who knows what happenes in the case of the tapped horn…
 decoud wrote:
Romy, I know you despise DIY, but isn't this so obscenely simple to build one may as well try it? Presumably, all one needs is a length of large diameter cylindrical pipe, with a partition running down the middle? If one uses two pipes of slightly different diameter, with sand poured between them, even the material the pipes are made of would not matter, no?

Oh, No! It is very much not on my horizons. If I do it then I certainly would not do it myself but commission right people to do the job and manage the project but to do it I would need some reasoning: theoretical or empirical.  Empirically I have no data as I never heard properly made tapped horns. I do not have problem with my bass and I never had any of my visitors pointed out in my bass the specific shortcomings that they feel need to be addressed. It is not that I do not recognize in my current bass specific idiosyncrasies that I would like to be doe different but I have no evidences that tapped horn or even conventional bass horn would address them. Theoretically I as well see justifications why tapped horn would be a more advance option. This is why I am asking what is going on with tapped horns…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-30-2009 Post does not mapped to Knowledge Tree
serenechaos
lost alamos
Posts 86
Joined on 12-01-2007

Post #: 16
Post ID: 10400
Reply to: 10395
Sub bass hi pass
fiogf49gjkf0d
 Romy the Cat wrote:
I think it might be very interesting to introduce the high-pass filtration for tapped horn and to see how it behaves. It is not only about thermal overload and restriction of excursion. The unloading of none-used bass generally clean-up the transparency of band-bass very positively. The benefits might wary with the drivers and the way in which the driver is damped. You might want to try it, get a cheap digital crossover and try different slopes between 10Hz and 20Hz. You would not need to listen the absolute quality but rather the pattern in which Sound night be changing. If you found that let say at 14Hz you would like to roll of your tapped horn with second Bessel order then you would always be able to implement it in your tapped horn’s bass amp.
 
The Cat

blah, blah, blah, all that stuff...
yes, yes, I was thinking along those lines last night after I posted it, and wondering if effects of hi pass, (not just steep acoustic roll off of driver), in the amp, relieving unwanted signal getting to the drivers might be a good thing.  Building band-pass filters, into the amp actually. 

I thought at least that channel was done.
Damn Cat!
Ok, digital experiments, then call Dave Slagle, get good iron & filter parts if it helps. 

robert

04-30-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,511
Joined on 05-28-2004

Post #: 17
Post ID: 10401
Reply to: 10400
More about high-pass, if it is necessary
fiogf49gjkf0d

 serenechaos wrote:

blah, blah, blah, all that stuff...
yes, yes, I was thinking along those lines last night after I posted it, and wondering if effects of hi pass, (not just steep acoustic roll off of driver), in the amp, relieving unwanted signal getting to the drivers might be a good thing.  Building band-pass filters, into the amp actually. 

I thought at least that channel was done.
Damn Cat!
Ok, digital experiments, then call Dave Slagle, get good iron & filter parts if it helps. 

Obviously when in amp filtration is THE filtration but…

1)    You do not know if it is necessary

2)    You do not know what is necessary (cut off and slop)

3)    If it is high order then you do not know if the topology of your amp would candle it

4)    You do not know if you need to use RL filtration.

The last one is the tricky one. The series capacitance is bad but if you channel does just LF, let say below a few hundred Hertz then, the negative contribution of series capacitance is kind of questionable…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-30-2009 Post does not mapped to Knowledge Tree
serenechaos
lost alamos
Posts 86
Joined on 12-01-2007

Post #: 18
Post ID: 10402
Reply to: 10401
How to hi pass
fiogf49gjkf0d
on 1) & 2); by "digital experiments" I meant "get a cheap digital crossover and try different slopes;

on 3) & 4): Dave Slagle, Intact Audio, knows a LOT more about transformers than I do, and the nickle autoformers I got from him work so well, I totally trust his (and/or Jeffrey Jackson's) judgment to over my "guess work," etc.  I don't trust myself to do everything from scratch, need to/eaisier to commission some things to someone else. 

robert 
04-30-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,511
Joined on 05-28-2004

Post #: 19
Post ID: 10403
Reply to: 10402
I do not think it has anything to do with transformers
fiogf49gjkf0d

 serenechaos wrote:

on 3) & 4): Dave Slagle, Intact Audio, knows a LOT more about transformers than I do, and the nickle autoformers I got from him work so well, I totally trust his (and/or Jeffrey Jackson's) judgment to over my "guess work," etc.  I don't trust myself to do everything from scratch, need to/eaisier to commission some things to someone else. 

If you drive your LF section with SET amplifier with a transformer or use Innerstage transformer then use transformers to roll off LF and introduction of high-pass via transformers is not a good idea. You would need an explicit filter. Transformers when they roll off distort a lot and they would roll of with dependency with the strength of the signal - you might not want it.  The problem with the bass nigh-pass is that it might demand high order and it might be hard to do in a simple SET as most of SETs use very simple circuit and there is not a lot of space (design-vise) where filters or 2-4 order might be implemented. The trapped horns are looks like not overly sensitive to begin with, so you most like use higher power and higher gain amps. Anyhow, the key is to found out if the trapped horn in your implementation and with your driver need a roll off then you might see where to put the filters. Do not forget that second order nigh-pass on speaker lever would mean CL chain that would not affect damping and therefore it might be tried in there… Theoretically to unload the unused lowers bass it would be nice for bass amps as well but it you have SET in Class A with sufficient amount of spare inductance then it would not mater….

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-30-2009 Post does not mapped to Knowledge Tree
serenechaos
lost alamos
Posts 86
Joined on 12-01-2007

Post #: 20
Post ID: 10404
Reply to: 10403
Amp for tapped horns
fiogf49gjkf0d
Yes, tapped horns are lower efficiency, mine are 105 dB (not 108 - 110 dB like the rest of the system). 

I don't even KNOW that SET or Class A is automatically appropriate for tapped horns... 
Something like op amp driven PP in class AB might even work better, for all I know... 
But if I do conclude the need for a hi-pass filter, I'll definitely need to talk to someone who knows more about such things than I do...

But thanks for pointing out possible merit of high pass, and possible problems in implementation!

Robert
04-30-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,511
Joined on 05-28-2004

Post #: 21
Post ID: 10405
Reply to: 10404
Many options are available
fiogf49gjkf0d

 serenechaos wrote:
Yes, tapped horns are lower efficiency, mine are 105 dB (not 108 - 110 dB like the rest of the system). 

Actually the 105dB efficiency is very good efficiency and with this efficiency any 20W-30W DSET amp would do fine, unless you have over 1700 cub feet listening room

 serenechaos wrote:

I don't even KNOW that SET or Class A is automatically appropriate for tapped horns...
The problem is not with “appropriate” but with debility of most of SS PP amps to do proper bass, at least I was not able to come across…. 
 serenechaos wrote:
Something like op amp driven PP in class AB might even work better, for all I know...  But if I do conclude the need for a hi-pass filter, I'll definitely need to talk to someone who knows more about such things than I do... 

You might look at the amps with feedback, it would be better for damping and you would be able to stick an additional filtration into feedback. So, you might have 12dB in open loop, for instance on grids, and 12dB from closed loop… many options are available

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-05-2009 Post mapped to one branch of Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,511
Joined on 05-28-2004

Post #: 22
Post ID: 10433
Reply to: 10333
Here is a good tapped horn reads by John Hasquin
fiogf49gjkf0d

This is the text that John posted a few years back at Triode Mafia. John allowed me to post it here warning that he have learned more about tapped horn since then and hat his opinion might have changed since then.

-- ********************************************************

As a nice start, I would highly recommend reading Tom Danley’s white paper on what tapped horn technology is. It is a very interesting concept. Might I add that it works quite well.

Tapped horn white paper --> http://www.danleysoundlabs.com/pdf/danley_tapped.pdf

If for some reason this link doesn’t work for you, just go to the technical download area of Danley Sound Labs.

It is also very useful to read the pending international patent.

Tapped horn patent application --> http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=WO2007109075&F=0

The short version is that a tapped horn uses the secondary side of a woofer to fill in the dips in the horns response due to an undersized mouth. This is done by aligning the phasing properties of the horn in relation to the T/S parameters of the woofer. As the wavelength of the note played changes, so does the phase relationship of the woofer in regards to the horn. At higher frequencies, the horn only makes use of the front side of the woofer cone. As frequency goes down, the back side of the woofer cone progressively starts to contribute as additional driving surface area for the horn. It’s like having a variable woofer cone, but it is done automatically as frequency and phase changes. Pure genius in my opinion. Don’t worry, its easy to design for.

Before I go into how I designed my tapped horns I would like to touch on some very important things that separate tapped horns from conventional horns. I will break this down point-by-point. I will point out both positive and negative aspects of the tapped horn. I will continue to add to this thread as I have more to add. I hope you guys find this interesting and it motivates you to build your own horns.

1.) The primary reason behind using a tapped horn is its size. It is now possible to make a horn extremely small in relation to the lowest frequency it will play. For all practical purposes, you only need a mouth large enough to allow you to mount your woofer. That’s it, it can be quite small.

2.) The tapped horn does not suffer from group delay as bass reflex and conventional front loaded horns. Group delay is the primary culprit that causes “slow” bass. If you have ever heard bass that sounds like it is half a beat behind, you have heard the effects of group delay. The tapped horn avoids this by virtue of its design. Because the backside of the woofer is in close proximity of the mouth, time of flight for the sound is the same as a direct radiator. Due to the air volume inside a tapped horn being much less than a conventional horn, it can quickly pressurize this air and keep proper phase with the back side of the woofer. This has allowed me to finally time align my horns the way I wished I could. Integration is much better than my old 37Hz subwoofer horns. Not to mention the tapped horns are ¼ the size.

3.) One of the most magnificent benefits of tapped horns comes again from the woofer being in close proximity of the mouth. I have come to realize that this can contribute to much more interesting sonic textures. The tapped horn allows the higher harmonic content of instruments to come through. In a conventional front loaded horn, all the folds act as a muffler and acoustically attenuate these harmonics. What I have found is these harmonics are important in reconstructing a convincing field of depth. The realism is greatly enhanced with these harmonics present. A very interesting effect. This works well in my 40Hz tapped horns because the horn’s overall sensitivity is within a dB or two of the woofer’s own raw sensitivity. I’m using B&C Speakers 8PE21 woofers with 98dB sensitivity. The horns overall sensitivity is 100dB. The combined high sensitivity with the detailed light weight cones is capable of resolving the complex textures involved. In addition, the light cones help control over shoot and stored energy smearing of the signal. You may be thinking that the tapped horn is not providing much loading being it is only doing 100dB and the woofer was already 98dB. Here’s the deal, high efficiency woofers have a falling low frequency response. The 8PE21’s sensitivity is only 70dB at 40Hz, while in the tapped horn it is doing 100dB. That’s 30dB of gain on the low end. This type of gain is hard to come by even in a conventional front loaded horn.

4.) Now for a few issues you must consider with tapped horns. The most pressing issue to me is distortion. While the tapped horns still have much less distortion than a bass reflex, infinite baffle, or acoustic suspense subwoofer, it still has more than a conventional front loaded. Let me explain why. In a conventional front loaded horn you usually have a rear chamber that has its volume tuned to resonate the woofer at the horn’s flare cutoff. This is all part of annulling the throat reactance to get the lowest frequency output from the horn. Due to the design nature of the tapped horn, there is no rear chamber. In a tapped horn you must use the back side of the woofer in a phase additive manner to fill in the dips in response. Since there is no back chamber acting as an air spring to help control cone motion, the result is more even order distortion. This is because the uneven excursion (dumax) becomes a little pronounced in a tapped horn. When the pressure wave inside the horn is phase additive, it pushes on the cone, when the pressure wave is phase subtractive, it pulls on the cone and exaggerates uneven excursion. So, how bad is the even order distortion of the tapped horn? Well, I don’t have exact numbers, but from all indications and past experience, I would say if all things were equal (but size of the horns of course) a conventional horn would have 1.5% distortion, then the tapped horn would be in the neighborhood of 8% - 10%. That does look bad, but it is almost all even order harmonics. Remember people have been living with fart machines for subwoofer for a long time. Most home theater subwoofers push 20% or more distortion at high excursion.

5.) Distortion is not all gloom and doom for the tapped horn. If we are smart we can still design a tapped horn with distortion almost as low as a conventional front loaded horn with a rear chamber. The way around this is to use push-pull woofers. The two woofers share a common chamber that feeds the horn throat. One woofer is reverse mounted and also has its polarity reversed. This sets up a push-pull pair that will cancel the uneven dumax of the woofers. It will also cancel even order harmonics just the same as it happens in push-pull amplifiers. In addition, it linearizes excursion cased Bl fade. As one woofer’s coil begins to leave the gap, the other drives deeper.

6.) Having built both push-pull and single woofer tapped horns; I can say the push-pull pair is the way to go. The sound difference can be heard if you listen to recordings with very dry and tight bass. The even order distortion of the single woofer horn rounds and smoothes the attack of the bass notes. It is not the end of the world, but well worth the extra effort to design with a push-pull pair.




"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
05-05-2009 Post does not mapped to Knowledge Tree
JLH
Indianapolis, IN U.S.A.
Posts 42
Joined on 07-20-2004

Post #: 23
Post ID: 10435
Reply to: 10405
More thoughts on tapped horns
fiogf49gjkf0d

I am adding to what Romy just posted for me. See the below for more information about tapped horns.

Rgs, JLH

*******************************************************************


So, what does a tapped horn look like? There are several ways to fold, but I chose this method because it was simple and easy to construct. It also blends more with today’s modern tall skinny speaker look.

There are no braces in the above picture. The below picture is the same horn with a brace that runs the full length of the horn. This was just enough bracing for the horn.

Below I’m putting the woofer in through the access panel. I like the way this tapped horn turned out because the woofer is hidden from sight, and the access panel is in the back.

Here are the input parameters for the horn in David McBean’s Hornresp program.

And the predicted response

The frequency peaks above 165Hz are not there in real life. The horn’s folding could be filtering some of it out, or Hornresp is doing some squirrelly computations that don’t exist.

More later

Rgs, John

05-05-2009 Post does not mapped to Knowledge Tree
JLH
Indianapolis, IN U.S.A.
Posts 42
Joined on 07-20-2004

Post #: 24
Post ID: 10436
Reply to: 10405
Continuing the tapped horn ideas
fiogf49gjkf0d

Here are some real world measurements made at the 2007 NYC sub shoot out. The distortion numbers and characteristics should help us understand the difference between tapped horn distortion and conventional front loaded horn distortion.

The first distortion graph is the Danley TH-115. This is a tapped horn that uses a single high excursion 15” woofer. Testing was done at 100Wrms input. You’ll notice that distortion is in the 7% to 13.5% range for most of the frequency. However, most people, including myself, would describe Danley bass as being very clean and low. Danley bass tends to sound like it needs to be turned up because the perception is that it lacks the upper harmonic distortion that our brain interprets as loudness. This is one reason why some people prefer direct radiating Scoop horns. Scoops can “sound” louder because of their high distortion in the mid-bass/kick drum range.


 

 

The second graph is the EM Acoustic MSE-118 subwoofer horn. This is a more conventional front loaded subwoofer horn that uses a single 18” woofer. It has a sealed and tuned rear chamber to help control cone motion and the low frequency tuning. The testing setup was the same as the TH-115. The thing you’ll notice is the distortion stays below 4% through most of the frequency range. As expected, as you near the flare cutoff of the horn, distortion increases very quickly. Even the TH-115 is not immune (See above graph for TH-115) to this.


More discussion to come on these graphs and what they mean.

Rgs, John

05-05-2009 Post does not mapped to Knowledge Tree
JLH
Indianapolis, IN U.S.A.
Posts 42
Joined on 07-20-2004

Post #: 25
Post ID: 10437
Reply to: 10405
More tapped horn stuff
fiogf49gjkf0d
I have been doing some work with integration of tapped horns. I have discovered some interesting things that are not being discussed on any other forums. I’ll start at the beginning so a full picture will be clear.

At first I placed the tapped horn such that its woofer was time aligned with my large tractrix horn’s woofer. I found that this gave reasonable results. However, I felt that the pacing between the tractrix mid-bass horn and the tapped horn wasn’t quite right. I proceeded to make exact distance measurements so both horns were time aligned per the center section of their voice coils. The effect this had was interesting. The bass range from about 50Hz and down, was excellent. However, something was still off about the 70Hz to 100Hz range. There was a strange phasiness to the sound. What to do?

I stopped for a moment and started to think about what was actually happening. Reading back through my notes on tapped horns, I believed I found my answer. The main principle that allows the tapped horn to work involves its varying phase properties. In the low frequencies the phase relationship is such that the front and back side of the cone is in a phase additive mode. Therefore, both sides of the woofer are contributing to the horn. As frequency climbs, the back side of the cone progressively goes out of phase. This gradually reduces the cone’s back side contribution to the horn. What I believe was happening is the phase change of the tapped horn was having an unexpected interaction with my mid-bass horn. This is why I could only get perfect integration over a very short frequency range. Great, what am I going to do now?

Well, after thinking some more, I decided that I could still have proper time alignment, but change the phase relationship between the tapped horn and my mid-bass horn. I did this by keeping the time of flight distance along an arc in reference to the listening position. I then moved the tapped horn along this arc until the two horns stopped interfering with one another. This worked like a charm. Instead of being right next to the mid-bass horns, the tapped horns are now about 2 and ½ feet to the outside of each mid-bass horn. Sound location is not an issue because the tapped horns are only covering material below 80Hz, so they are very non-directional. Problem solved. So, far this is the best sound I have had in my system. I’ve got the dynamics I’ve always loved, but have better integration than before.

Rgs, John
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