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Old 7th July 2013, 10:00 AM   #121
Radian is offline Radian  Germany
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Quote:
Originally Posted by Rewind View Post
Radian: Are you sure a phase plug is needed for the Fane driver when it driven to just 400 or 500hz?
Simple answer, yes. It is not so much about the classical phase plug function as it its the way the compression is achieved. It will exhibit more authority on the low end as well as on the high end. IMO the compression needs to take place as close to the source as possible and as smooth as possible. Sudden changes of direction, Edges, and flat surfaces that the air is pressed against are all sources of phase and amplitude discontinuities. Throw a stone into water and you will see how compression needs to take place.

Klaus

Last edited by Radian; 7th July 2013 at 10:04 AM.
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Old 7th July 2013, 03:40 PM   #122
Rewind is offline Rewind  Sweden
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And you have tested this with the Fane driver or is this a theory so far? I bet it would require many horn and phase plug versions before one would
get it right. Quite an undertaking. At the same time I wonder which driver I should horn load. A 12 inch JBL 2204H or the Fane Studio 8M? The JBL would reach lower but the Fane would achieve very clear midrange. Yet the JA 6681B will take over at 350hz so what is the use of the Fanes excellent midrange? It depends a lot I think on the subwoofer. Angelo tried all this before and he came to the conclusion that the fact that his 12" Beyma 12P80ND could reach lower frequencies was better because he did not want to split the midbass. The Fane seem to start at about 150hz. Too high probably, for a subwoofer. It is a matter of taste I guess. The Fane is so detailed for cone driver!

Last edited by Rewind; 7th July 2013 at 03:48 PM.
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Old 8th July 2013, 01:37 AM   #123
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Quote:
Originally Posted by Radian View Post
Sorry I have not checked this thread for a while.
I had a drawing done in 2010 for a discussion in the Analog Forum.
It was very crude but I show it anyway. The widest part of the phase
plug should be at the edge surround of the cone and not like in the
drawing that shows it above that point.

Starting at the pole piece of the speaker a phase plug should be
progressively open up, following the contour of the membrane. I would start
at about 3mm clearance to the cone at the pole piece and try to end at
the edge surround between about 8-15mm. Of course this depends on the desired
compression ratio and the size of the cone.
This way the compression happens almost like in a WE555 driver.
In my opinion this is the most important feature in the WE555 that makes
it sound so natural. If one would envision a fluid being compressed in a
normal compression driver vs. the WE555 it would be clear what was the more
natural and smooth way.
With a cone speaker it is not any different.
To cover a third to halve of a cone with a flat piece of board is IMO not wise and far away
from optimized airflow. Great care is taken in a hf horn to find the best contour and good
throat transition and when it comes to low frequency reproduction we seem to forget everything.
As if the laws of physics do not matter as much at those frequencies.
At the moment I have no time to write my thoughts about the subject in more detail so this has to
do.
I am sorry what you saying might be accurate from general stand point but it does not back you your allegation that Romy upperbass channel with Fane is not done properly, First of all how do you know what horn Romy uses? Then, how do you know what Romy’s objectives were and what result he has. Why do you feel that Fane even need a phase plug? The Fane in this horn has extension all over 5K and phase plug just will push it to 8K. It is very difficult passive low-pass filter this driver as it has a lot of inductance, if so why would anybody ever want to extend the HF of this driver. Romy uses his upper bass horn up to 600Hz, why do you feel he would need to have more HF extension and phase plug? Did you use the Fane driver yourself? I wonder what rational you have to advocate that Romy horn was not done properly if you do not understand what the channel does.
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Old 8th July 2013, 01:44 AM   #124
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Quote:
Originally Posted by Radian View Post
It is not so much about the classical phase plug function as it its the way the compression is achieved. It will exhibit more authority on the low end as well as on the high end. IMO the compression needs to take place as close to the source as possible and as smooth as possible. Sudden changes of direction, Edges, and flat surfaces that the air is pressed against are all sources of phase and amplitude discontinuities. Throw a stone into water and you will see how compression needs to take place.
Sorry, Klaus, it does not back up with my experiments. I did use the Romy- like horn with Fane and did experiment with phase plug and I observed no influence to the lower knew of the horn. Even more, the use of phase plug leads to higher compression and higher HF extension. Both are not advisable for Fane. The higher HF extension will lead to sharper low pass filter with all consequential phase anomalies. I truly do not know why you advocate what you are advocating.
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Old 8th July 2013, 09:45 AM   #125
Rewind is offline Rewind  Sweden
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Seem like the consensus is pointing against a phase plug for hornloaded midbass cone drivers below 500Hz.

Could anyone share some light in the choice between a 8, 10 or 12" cone driver for hornloading below the JA6681B?
The Fane Studio 8M may start playing too high for good integration with a subwoofer. With a compression driver like the JA6681B, that reaches 300Hz, the Fane drivers good midrange tone may be superfluous. I have read that a good 12-21" subwoofer is lowpassed at 80Hz. Then the range between 80Hz and 150Hz is neglected when using Fane Studio 8M. A 12" midbass driver, like JBL 2204H, JBL E-120 or Beyma 12P80ND would cover this range better. But would they sound good in a horn? Are there better alternatives for hornloading 80Hz-300Hz? How would the size of the horn change from Romys/Trio's midbass horn?

I would appreciate your thoughts on this also.

Last edited by Rewind; 8th July 2013 at 10:07 AM.
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Old 8th July 2013, 10:19 AM   #126
3GGG is offline 3GGG  Australia
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I have the Fane 8m below the JA6681, it operates from 120Hz up to 350 Hz and rolls off at 6db. If you can find a 12" which goes down to 80Hz the mid bass horn is getting large, but it would enable a sub to be used , Maybe T-TQWT from 20 to 80HZ. I am building a 15Hz horn below the Fane to run form 20 Hz to 120Hz, then cross to the Fane and then the JA 6681.
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Old 8th July 2013, 10:47 AM   #127
Rewind is offline Rewind  Sweden
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There are two commercially avaliable speakers, La Grande Castine and the Cessaro Gamma, that use a 15" driver or a 11" driver, instead of the 8" Fane as a hornloaded midbass speaker. Here is Romy's thoughts about these.

GoodSoundClub - Romy the Cat's Site - The second "best" commercial horn speaker?>
"The upperbass is very narrow banded with 80-300Hz. That is a good range foe this topology of horn. I presume it it has a resonance somewhere around 80Hz and with a proper selection of driver it might work very well. The presence of the separate sub 80Hz section imidetaly brings this system from the state of stupid wishful thinking into a realm of very lucid design, my congratulations.
Looking at what you have done I think that the only “slippery” moment in this speaker is the high knee of the upperbass and lover knee of MF. If your MF driver goes down to 300Hz then it is very “pushy” I would say. That would require a good 120Hz -140Hz horn but your MF horn strike me as 170Hz-200Hz horn. I do not know you but let presume that since you did not make other mistakes then you know what you do and what you hear. Then you would not load into a 200Hz Le Cléac’h horn 300Hz compression driver with first order. Well, you might go for it if you need it and it you upperbass cannot go up enough but in your case, having the shallow upperbass horn and a phase plug in the upperbass, you have no necessity to kill the upperbass at 300Hz. So, if to presuming that you know what you hear and that your speaker sounds good then most likely here is what happen in them. You most likely do not let the MF god all the way down to 300Hz. You might highpass the upperbass at 300Hz electrically with your “crossover is full passive, first order” but in reality a single coil would not stop those drivers. At 300Hz the inductance of those midbass woofers become co-measurable with the inductance of the filter coil, so you crossover point slips all the way up. I might presume that the actual -3dB from upperbass you have at 700-1000Hz that would mask out your lower knee of your MF channel. So, the octave where your MF and upperbass work together you use as a virtual Macondo’s “Fundamental Channel”. This is might take how your speaker work if it sounds balanced.
Ok, to conclude the things. It looks like from what it presented now the speaker is done with no mistakes and even I can’t find a rational to bitch about them. I nominate this “La Grande Castine” as the second “The most promising ‘best’ commercial horn speaker” right after the Cessaro Gamma."

GoodSoundClub - Romy the Cat's Audio Site - The Cessaro Gamma tweeter criticism + some solutions.
"...The Gamma’s upperbass horn is too short. I make a conclusion is that the upperbass use too large throat perhaps 7”-8”/ This loading would be great for $15K acoustic system but not for $230K. The 100Hz might be loaded lower; I feel 3” is a critical throat diameter for 100Hz Tractrix and 4” for exponential. Then the use of TAD driver throughout… I have to admit that I am not a huge fun of TAD drivers. They have a good bacterially clean sound but truly nothing really special. Do you see yourself shopping for more interesting vintage driver for your loudspeakers AFTER your spend million dollars for your acoustic system? Then, the amplification…. At the level of $230K any acoustic system should come with own amplification, add price if you wish but the thinking about acoustic system at this level of seriousness must include the amp-driver interface. In the end - the bass. The Gamma’s bass solution is great for $50K but not for $230K. The objectionable bass must include open bottom bass solution. For ¼ million dollars you need to have separated lower and mid bass. The Gamma’s midbass might be OK (I do not know how good they made their W-bins) but as soon the array of those W-bins will be asked to push octaves lover then the moth rate then sound will turn to ****. It is not the Cessaro’s bad implementation – it is the topology’s limitation. It might be a solution for Cessaro to divide 2 of this 4 LF section for horn load midbass and 2 for sealed lower bass but it looks like they all horn loaded. If so, then it is not the $230K-worth solution but a comprise that might be used in the acoustic systems of $10K-$50K level…Macondo has the similar comprise letting the lover bass section to care the midbass. However, Macondo is a loudspeaker of $25K, thought Macondo does honest $25K. If Macondo were ¼ million dollars acoustic system then it would be very different set of solutions. Cessaro Gamma does cost Gamma ¼ million but does not offers for this money any design substance.

Rgs, Romy the Cat"
Attached Images
File Type: jpg la-grande-castine-loudspeaker_52.jpg (36.6 KB, 179 views)
File Type: jpg gamma.5.jpg (51.7 KB, 177 views)

Last edited by Rewind; 8th July 2013 at 10:58 AM.
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Old 8th July 2013, 11:02 AM   #128
Rewind is offline Rewind  Sweden
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Quote:
Originally Posted by 3GGG View Post
I have the Fane 8m below the JA6681, it operates from 120Hz up to 350 Hz and rolls off at 6db. If you can find a 12" which goes down to 80Hz the mid bass horn is getting large, but it would enable a sub to be used , Maybe T-TQWT from 20 to 80HZ. I am building a 15Hz horn below the Fane to run form 20 Hz to 120Hz, then cross to the Fane and then the JA 6681.
Good luck. You have to let us know how the 15Hz horn sound crossed so high.
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Old 8th July 2013, 11:21 AM   #129
Rewind is offline Rewind  Sweden
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Back to the phase plugs again. Not sure of how his horn look like but AllenB seem to like his cone driver with a phase plug: Best 8" to 12" driver for 130hz tractrix horn
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Old 8th July 2013, 11:35 AM   #130
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Quote:
Originally Posted by 3GGG View Post
I have the Fane 8m below the JA6681, it operates from 120Hz up to 350 Hz and rolls off at 6db. If you can find a 12" which goes down to 80Hz the mid bass horn is getting large, but it would enable a sub to be used , Maybe T-TQWT from 20 to 80HZ. I am building a 15Hz horn below the Fane to run form 20 Hz to 120Hz, then cross to the Fane and then the JA 6681.
Quote:
Originally Posted by 3GGG View Post
I am building a 15Hz horn below the Fane to run form 20 Hz to 120Hz, then cross to the Fane and then the JA 6681.
3GGG, I would like to recommend you to think again about building a 15Hz horn as it is a bit contra-productive thing to do regardless of the horn design. For sure you can do whatever you want but I have a lot of experience of the subject. If you want your midbass horn for go down very low then do not target 15Hz but rather 35-45Hz. You will need to use close -bottom ULF section at the bottom regardless. If you do have midbass 3 octaves horn you will not be able to “stop” it properly.
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