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Chorus 1 Questions


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10 hours ago, 4JaxJags said:

 

So If I end up using a 7" total length tube/vent, would 4" away from the back wall be enough? 

(Someone who was an experienced speakerbuilder did some calcs & said a 7" vent would be ideal in a Chorus 1)

a four inch gap will work but rather why don't you start with a six inch long vent rather than seven inches, that will give you a little bit more room between the vent and the rear wall of the cabinet to breath? This is not about ideals this is about what works best. You can gain extra output by placing your speakers closer to the front wall or into the corners as well. When re tuning like this I generally shoot to lower the tuning frequency no more than three or four Hz. It does not sound like much but it will have a significant impact and you need to remember that your driver has limited travel and the manufacturer has already taken liberties and wanted to keep a safe margin now we are stretching that a second time so don't over do it. There are physical limits which don't give a hoot about ideals.

   You are going to do what you will so see what you think and if you are happy with that then that's all that matters. It all comes down to compromises, some are just better than others.

   For those who wish to experiment you can extend the vents out forward from the box this will not only work just fine (though it looks a bit odd) it will show you the impact of the proximity of the inside wall and the vent. At the tuning frequencies the box has no real impact upon the vents performance so long as the vents are nor close to the ground plane.

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I installed 4" inch inner diameter x 4-3/8 long port tubes from Parts Express in my Chorus I speakers (https://www.parts-express.com/speaker-cabinet-port-tube-4-id-x-4-3-8-l--260-411).  The outer diameter of the port tube is slightly smaller than the port opening in the motor board.  I put a few wraps of electrical tape around the end of the port tube that makes contact with the port opening and then pressure fit it into the motor board with some (gentle) assistance from a rubber mallet.   I have not measured the difference in frequency response but my subjective impressions are that the bass goes approximately 3-5 Hz lower and the midrange is less forward / "in your face" with the port tubes (which is a good thing in my listening room).  I did not use a longer port as it would interfere with the Crites crossovers I have installed in the base of the speaker.  

 

Jim 

IMG_0311.JPG

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On 1/24/2019 at 10:30 AM, MookieStl said:

There wasn't a tube in the port, only two holes cut in the front board. 

 

Matthews documented quite a bit in his thread at the time. I always like a good build thread.

 

 

Great thread. I have a set of parts for a Chorus I and I have some 1" Baltic on hand for a build. I figure on maybe making it bigger depending on what the guys with software say is best. Like these the MDF was damaged and no way to repair.

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Lol, as long as we are talking about X-periment, let us consider compromising the length after doing the work and listening. Like the idea as above @NY User...ends with a shorter port length for his purposes.

Another idea is, if the 7 inches turns out to be ideal, why not just port the vent? That is, drill a hole say, through the middle of the port length, thereby increasing airflow allowing more air to escape, which in turn allows the port end at rear of induction tube less turbulence.

Interesting thread, and you guys should know, my next Chorus, I promise to mod. Like the electrical tape idea at the port for snugging

up if needed, and Matthew did along with Mookie a great job on the Chorus project...imo:

 

On ‎1‎/‎26‎/‎2019 at 9:04 AM, NY User said:

I installed 4" inch inner diameter x 4-3/8 long port tubes from Parts Express in my Chorus I speakers (https://www.parts-express.com/speaker-cabinet-port-tube-4-id-x-4-3-8-l--260-411).  The outer diameter of the port tube is slightly smaller than the port opening in the motor board.  I put a few wraps of electrical tape around the end of the port tube that makes contact with the port opening and then pressure fit it into the motor board with some (gentle) assistance from a rubber mallet.   I have not measured the difference in frequency response but my subjective impressions are that the bass goes approximately 3-5 Hz lower and the midrange is less forward / "in your face" with the port tubes (which is a good thing in my listening room).  I did not use a longer port as it would interfere with the Crites crossovers I have installed in the base of the speaker.  

 

Jim 

IMG_0311.JPG

Nice job and, welcome to the forum, btw...:)

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I did some measurements today: The factory opening is 4 & 1/16. It is 13 & 1/4 inches from the INSIDE edge of the holes in the motorboard to the back wall. My crossovers were already upgraded when I got them (sonicaps) & are mounted in the factory location (on the inside the speaker terminal plate) so port length won't be an issue. 

20190127_140844_resized.jpg

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My two cents (just a little more than actual value) is to try the 4 3/8" port that NY user did. Minimum investment and easily reversible. Give the Klipsch engineers some credit, they did without a tube and they know what they are doing or we wouldn't love their products so much. A little tweak here and there is what makes this hobby fun. Once in place you should know if you're on the right track. Any additional length will have diminishing returns. The bass in the Chorus is supposed to be quick hitting, try to keep it that way.

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On 1/27/2019 at 9:22 AM, billybob said:

Lol, as long as we are talking about X-periment, let us consider compromising the length after doing the work and listening. Like the idea as above @NY User...ends with a shorter port length for his purposes.

Another idea is, if the 7 inches turns out to be ideal, why not just port the vent? That is, drill a hole say, through the middle of the port length, thereby increasing airflow allowing more air to escape, which in turn allows the port end at rear of induction tube less turbulence.

Interesting thread, and you guys should know, my next Chorus, I promise to mod. Like the electrical tape idea at the port for snugging

up if needed, and Matthew did along with Mookie a great job on the Chorus project...imo:

 

Nice job and, welcome to the forum, btw...:)

What exactly will drilling holes in the port do?  Are you saying through the side of the port half way up the port to possibly let more air into the tube?

8 hours ago, MookieStl said:

My two cents (just a little more than actual value) is to try the 4 3/8" port that NY user did. Minimum investment and easily reversible. Give the Klipsch engineers some credit, they did without a tube and they know what they are doing or we wouldn't love their products so much. A little tweak here and there is what makes this hobby fun. Once in place you should know if you're on the right track. Any additional length will have diminishing returns. The bass in the Chorus is supposed to be quick hitting, try to keep it that way.

On 1/27/2019 at 7:05 AM, pzannucci said:

Within reason, extending the ports in the same size box will trade a slight extension in bass for loss of amplitude.  Many times the amplitude can be made up for with proximity to wall or some boundary to balance it out.

 

Trying to point out the pros and cons also in my post.  Shorter port more punch if done correctly, less depth.  Longer port in box designed for short ports, as I said above ^^^^^^ Choose your poison.

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2 hours ago, pzannucci said:

What exactly will drilling holes in the port do?  Are you saying through the side of the port half way up the port to possibly let more air into the tube?

 

I didn't review his post for this response, but what I recall is the expressed notion of "increasing airflow" in the port.  And I take that as a misunderstanding of how ports work.  Sure, you want air to be able to easily get in and out of the port, but it's the mass of the entrained air that matters most.  Different port volume means different air mass, which means different frequency at which it resonates, and that's the major contribution it provides.

 

Putting hole(s) in the side of the tube, in my view, would merely relegate it to a tube the length to the nearest hole to the outside.  Now there may be some way in which the tube could thus act at multiple resonant frequencies, but I think it would not be as strongly a contributor as a single-purpose air mass would be.

 

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3 hours ago, pzannucci said:

What exactly will drilling holes in the port do?  Are you saying through the side of the port half way up the port to possibly let more air into the tube

Just an experimental idea is all. May be right, I may be wrong. Prodding the mind here to think. Toward the end of the port length an idea also. Thanks...

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2 hours ago, billybob said:

Just an experimental idea is all. May be right, I may be wrong. Prodding the mind here to think. Toward the end of the port length an idea also. Thanks...

The port supports a specific resistance and weight of air for the "spring" load against the woofer.  So to reduce that load through holes, reduces the weight and spring effect.  Just for sake of discussion.

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55 minutes ago, pzannucci said:

The port supports a specific resistance and weight of air for the "spring" load against the woofer.  So to reduce that load through holes, reduces the weight and spring effect.  Just for sake of discussion.

Just for the sake of discussion then, let us just suppose or maybe better pretend that the only way a speaker like this Chorus tuning port had to be in excess of a foot, to derive the frequency sought for. It would cost me nothing but the time and patience to introduce a port with a length that could fit inside without causing unwanted turbulence caused by the compressed air so near the rear of the speaker. Certainly I would experiment with at least one 1/2 inch hole cut through both or a single side of the port material of each. If I did not lose the slam effect, might would proceed farther. Say if because can say, the K-48-E used in the pair I had was not anything, in the way of bass shy, Whether the effect by overcome by moderate to higher volume, I can only imagine. I do know that, as an analogy that perforated or mesh satellite dishes (c-band) were wind resistant up to a certain rated and test mph of direct wind. The peak of their capacity was when exceeded there resistance and the dish appears solid to the wind where, the dish fails. An example is in the Turks & Caicos Islands

where back in the 80's, a local cable dish farm suffered catastrophic los due to a hurricane where the only dish reflector left standing intact

was the wind resistant Paraclipse beyond the rated wind speed.

What does this have to do with speakers? Not really sure except, testing gets you there beyond physics and theory. Once again, just

provoking thought nothing more.

Another idea I suppose is to create a port of a given length and terminate end with a 45 degree, such in the case of PVC but, yes, there

is only so much creativity and real world physics will allow. Thanks for your patience thus far. Thanks.

 

 

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the driver will be the ultimate determining factor as to how low you can tune. You just can't pull numbers out of the air it does not work that way. The woofer drives the vent and you can't tune much lower than the woofer is capable of playing. The vent is used to damp woofer resonance so that frequency (woofer/box resonance) is what you want to tune for, the air in the vent will resonate at the same frequency but in anti phase to the woofer and the air mass in the vent damps or loads the woofer so it cannot tear itself apart at full resonance. Further vents don't much like to be bent. There are lots of books or good sites which explain how to tune a woofer vent and which explain the process, this has been around and well understood for a long time now.

   Have fun experimenting. You will find that when the vent is tuned properly the woofer stops moving and it is the air in the vent which is doing all the work. If your woofer is dancing around you have missed the critical frequency.

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9 hours ago, pzannucci said:

 

Trying to point out the pros and cons also in my post.  Shorter port more punch if done correctly, less depth.  Longer port in box designed for short ports, as I said above ^^^^^^ Choose your poison.

For the record, I was agreeing with you. Klipsch had short ports (or no tube just the 1" depth of the motorboard) for a reason. Tweak away but don't go so far as to lessen the "punch"! For me, that's the fun part.

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